* [PATCH v5 01/34] tracing: Add a comment about ftrace_regs definition
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
@ 2023-12-18 13:11 ` Masami Hiramatsu (Google)
2024-01-05 17:12 ` Mark Rutland
2023-12-18 13:11 ` [PATCH v5 02/34] x86: tracing: Add ftrace_regs definition in the header Masami Hiramatsu (Google)
` (32 subsequent siblings)
33 siblings, 1 reply; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:11 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
To clarify what will be expected on ftrace_regs, add a comment to the
architecture independent definition of the ftrace_regs.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Add instruction pointer
Changes in v2:
- newly added.
---
include/linux/ftrace.h | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index e8921871ef9a..8b48fc621ea0 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -118,6 +118,32 @@ extern int ftrace_enabled;
#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
+/**
+ * ftrace_regs - ftrace partial/optimal register set
+ *
+ * ftrace_regs represents a group of registers which is used at the
+ * function entry and exit. There are three types of registers.
+ *
+ * - Registers for passing the parameters to callee, including the stack
+ * pointer. (e.g. rcx, rdx, rdi, rsi, r8, r9 and rsp on x86_64)
+ * - Registers for passing the return values to caller.
+ * (e.g. rax and rdx on x86_64)
+ * - Registers for hooking the function call and return including the
+ * frame pointer (the frame pointer is architecture/config dependent)
+ * (e.g. rip, rbp and rsp for x86_64)
+ *
+ * Also, architecture dependent fields can be used for internal process.
+ * (e.g. orig_ax on x86_64)
+ *
+ * On the function entry, those registers will be restored except for
+ * the stack pointer, so that user can change the function parameters
+ * and instruction pointer (e.g. live patching.)
+ * On the function exit, only registers which is used for return values
+ * are restored.
+ *
+ * NOTE: user *must not* access regs directly, only do it via APIs, because
+ * the member can be changed according to the architecture.
+ */
struct ftrace_regs {
struct pt_regs regs;
};
^ permalink raw reply related [flat|nested] 56+ messages in thread* Re: [PATCH v5 01/34] tracing: Add a comment about ftrace_regs definition
2023-12-18 13:11 ` [PATCH v5 01/34] tracing: Add a comment about ftrace_regs definition Masami Hiramatsu (Google)
@ 2024-01-05 17:12 ` Mark Rutland
0 siblings, 0 replies; 56+ messages in thread
From: Mark Rutland @ 2024-01-05 17:12 UTC (permalink / raw)
To: Masami Hiramatsu (Google)
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Mon, Dec 18, 2023 at 10:11:44PM +0900, Masami Hiramatsu (Google) wrote:
> From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
>
> To clarify what will be expected on ftrace_regs, add a comment to the
> architecture independent definition of the ftrace_regs.
>
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Mark.
> ---
> Changes in v3:
> - Add instruction pointer
> Changes in v2:
> - newly added.
> ---
> include/linux/ftrace.h | 26 ++++++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
>
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index e8921871ef9a..8b48fc621ea0 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -118,6 +118,32 @@ extern int ftrace_enabled;
>
> #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
>
> +/**
> + * ftrace_regs - ftrace partial/optimal register set
> + *
> + * ftrace_regs represents a group of registers which is used at the
> + * function entry and exit. There are three types of registers.
> + *
> + * - Registers for passing the parameters to callee, including the stack
> + * pointer. (e.g. rcx, rdx, rdi, rsi, r8, r9 and rsp on x86_64)
> + * - Registers for passing the return values to caller.
> + * (e.g. rax and rdx on x86_64)
> + * - Registers for hooking the function call and return including the
> + * frame pointer (the frame pointer is architecture/config dependent)
> + * (e.g. rip, rbp and rsp for x86_64)
> + *
> + * Also, architecture dependent fields can be used for internal process.
> + * (e.g. orig_ax on x86_64)
> + *
> + * On the function entry, those registers will be restored except for
> + * the stack pointer, so that user can change the function parameters
> + * and instruction pointer (e.g. live patching.)
> + * On the function exit, only registers which is used for return values
> + * are restored.
> + *
> + * NOTE: user *must not* access regs directly, only do it via APIs, because
> + * the member can be changed according to the architecture.
> + */
> struct ftrace_regs {
> struct pt_regs regs;
> };
>
^ permalink raw reply [flat|nested] 56+ messages in thread
* [PATCH v5 02/34] x86: tracing: Add ftrace_regs definition in the header
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
2023-12-18 13:11 ` [PATCH v5 01/34] tracing: Add a comment about ftrace_regs definition Masami Hiramatsu (Google)
@ 2023-12-18 13:11 ` Masami Hiramatsu (Google)
2023-12-18 13:12 ` [PATCH v5 03/34] function_graph: Convert ret_stack to a series of longs Masami Hiramatsu (Google)
` (31 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:11 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Add ftrace_regs definition for x86_64 in the ftrace header to
clarify what register will be accessible from ftrace_regs.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Add rip to be saved.
Changes in v2:
- Newly added.
---
arch/x86/include/asm/ftrace.h | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 897cf02c20b1..415cf7a2ec2c 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -36,6 +36,12 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr)
#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
struct ftrace_regs {
+ /*
+ * On the x86_64, the ftrace_regs saves;
+ * rax, rcx, rdx, rdi, rsi, r8, r9, rbp, rip and rsp.
+ * Also orig_ax is used for passing direct trampoline address.
+ * x86_32 doesn't support ftrace_regs.
+ */
struct pt_regs regs;
};
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 03/34] function_graph: Convert ret_stack to a series of longs
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
2023-12-18 13:11 ` [PATCH v5 01/34] tracing: Add a comment about ftrace_regs definition Masami Hiramatsu (Google)
2023-12-18 13:11 ` [PATCH v5 02/34] x86: tracing: Add ftrace_regs definition in the header Masami Hiramatsu (Google)
@ 2023-12-18 13:12 ` Masami Hiramatsu (Google)
2023-12-18 13:12 ` [PATCH v5 04/34] fgraph: Use BUILD_BUG_ON() to make sure we have structures divisible by long Masami Hiramatsu (Google)
` (30 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:12 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
In order to make it possible to have multiple callbacks registered with the
function_graph tracer, the retstack needs to be converted from an array of
ftrace_ret_stack structures to an array of longs. This will allow to store
the list of callbacks on the stack for the return side of the functions.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
include/linux/sched.h | 2 -
kernel/trace/fgraph.c | 124 ++++++++++++++++++++++++++++---------------------
2 files changed, 71 insertions(+), 55 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 292c31697248..4dab30f00211 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1390,7 +1390,7 @@ struct task_struct {
int curr_ret_depth;
/* Stack of return addresses for return function tracing: */
- struct ftrace_ret_stack *ret_stack;
+ unsigned long *ret_stack;
/* Timestamp for last schedule: */
unsigned long long ftrace_timestamp;
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index c83c005e654e..30edeb6d4aa9 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -25,6 +25,18 @@
#define ASSIGN_OPS_HASH(opsname, val)
#endif
+#define FGRAPH_RET_SIZE sizeof(struct ftrace_ret_stack)
+#define FGRAPH_RET_INDEX (ALIGN(FGRAPH_RET_SIZE, sizeof(long)) / sizeof(long))
+#define SHADOW_STACK_SIZE (PAGE_SIZE)
+#define SHADOW_STACK_INDEX \
+ (ALIGN(SHADOW_STACK_SIZE, sizeof(long)) / sizeof(long))
+/* Leave on a buffer at the end */
+#define SHADOW_STACK_MAX_INDEX (SHADOW_STACK_INDEX - FGRAPH_RET_INDEX)
+
+#define RET_STACK(t, index) ((struct ftrace_ret_stack *)(&(t)->ret_stack[index]))
+#define RET_STACK_INC(c) ({ c += FGRAPH_RET_INDEX; })
+#define RET_STACK_DEC(c) ({ c -= FGRAPH_RET_INDEX; })
+
DEFINE_STATIC_KEY_FALSE(kill_ftrace_graph);
int ftrace_graph_active;
@@ -69,6 +81,7 @@ static int
ftrace_push_return_trace(unsigned long ret, unsigned long func,
unsigned long frame_pointer, unsigned long *retp)
{
+ struct ftrace_ret_stack *ret_stack;
unsigned long long calltime;
int index;
@@ -85,23 +98,25 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
smp_rmb();
/* The return trace stack is full */
- if (current->curr_ret_stack == FTRACE_RETFUNC_DEPTH - 1) {
+ if (current->curr_ret_stack >= SHADOW_STACK_MAX_INDEX) {
atomic_inc(¤t->trace_overrun);
return -EBUSY;
}
calltime = trace_clock_local();
- index = ++current->curr_ret_stack;
+ index = current->curr_ret_stack;
+ RET_STACK_INC(current->curr_ret_stack);
+ ret_stack = RET_STACK(current, index);
barrier();
- current->ret_stack[index].ret = ret;
- current->ret_stack[index].func = func;
- current->ret_stack[index].calltime = calltime;
+ ret_stack->ret = ret;
+ ret_stack->func = func;
+ ret_stack->calltime = calltime;
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
- current->ret_stack[index].fp = frame_pointer;
+ ret_stack->fp = frame_pointer;
#endif
#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
- current->ret_stack[index].retp = retp;
+ ret_stack->retp = retp;
#endif
return 0;
}
@@ -148,7 +163,7 @@ int function_graph_enter(unsigned long ret, unsigned long func,
return 0;
out_ret:
- current->curr_ret_stack--;
+ RET_STACK_DEC(current->curr_ret_stack);
out:
current->curr_ret_depth--;
return -EBUSY;
@@ -159,11 +174,13 @@ static void
ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
unsigned long frame_pointer)
{
+ struct ftrace_ret_stack *ret_stack;
int index;
index = current->curr_ret_stack;
+ RET_STACK_DEC(index);
- if (unlikely(index < 0 || index >= FTRACE_RETFUNC_DEPTH)) {
+ if (unlikely(index < 0 || index > SHADOW_STACK_MAX_INDEX)) {
ftrace_graph_stop();
WARN_ON(1);
/* Might as well panic, otherwise we have no where to go */
@@ -171,6 +188,7 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
return;
}
+ ret_stack = RET_STACK(current, index);
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
/*
* The arch may choose to record the frame pointer used
@@ -186,22 +204,22 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
* Note, -mfentry does not use frame pointers, and this test
* is not needed if CC_USING_FENTRY is set.
*/
- if (unlikely(current->ret_stack[index].fp != frame_pointer)) {
+ if (unlikely(ret_stack->fp != frame_pointer)) {
ftrace_graph_stop();
WARN(1, "Bad frame pointer: expected %lx, received %lx\n"
" from func %ps return to %lx\n",
current->ret_stack[index].fp,
frame_pointer,
- (void *)current->ret_stack[index].func,
- current->ret_stack[index].ret);
+ (void *)ret_stack->func,
+ ret_stack->ret);
*ret = (unsigned long)panic;
return;
}
#endif
- *ret = current->ret_stack[index].ret;
- trace->func = current->ret_stack[index].func;
- trace->calltime = current->ret_stack[index].calltime;
+ *ret = ret_stack->ret;
+ trace->func = ret_stack->func;
+ trace->calltime = ret_stack->calltime;
trace->overrun = atomic_read(¤t->trace_overrun);
trace->depth = current->curr_ret_depth--;
/*
@@ -262,7 +280,7 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
* curr_ret_stack is after that.
*/
barrier();
- current->curr_ret_stack--;
+ RET_STACK_DEC(current->curr_ret_stack);
if (unlikely(!ret)) {
ftrace_graph_stop();
@@ -305,12 +323,13 @@ unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
struct ftrace_ret_stack *
ftrace_graph_get_ret_stack(struct task_struct *task, int idx)
{
- idx = task->curr_ret_stack - idx;
+ int index = task->curr_ret_stack;
- if (idx >= 0 && idx <= task->curr_ret_stack)
- return &task->ret_stack[idx];
+ index -= FGRAPH_RET_INDEX * (idx + 1);
+ if (index < 0)
+ return NULL;
- return NULL;
+ return RET_STACK(task, index);
}
/**
@@ -332,18 +351,20 @@ ftrace_graph_get_ret_stack(struct task_struct *task, int idx)
unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
unsigned long ret, unsigned long *retp)
{
+ struct ftrace_ret_stack *ret_stack;
int index = task->curr_ret_stack;
int i;
if (ret != (unsigned long)dereference_kernel_function_descriptor(return_to_handler))
return ret;
- if (index < 0)
- return ret;
+ RET_STACK_DEC(index);
- for (i = 0; i <= index; i++)
- if (task->ret_stack[i].retp == retp)
- return task->ret_stack[i].ret;
+ for (i = index; i >= 0; RET_STACK_DEC(i)) {
+ ret_stack = RET_STACK(task, i);
+ if (ret_stack->retp == retp)
+ return ret_stack->ret;
+ }
return ret;
}
@@ -357,14 +378,15 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
return ret;
task_idx = task->curr_ret_stack;
+ RET_STACK_DEC(task_idx);
if (!task->ret_stack || task_idx < *idx)
return ret;
task_idx -= *idx;
- (*idx)++;
+ RET_STACK_INC(*idx);
- return task->ret_stack[task_idx].ret;
+ return RET_STACK(task, task_idx);
}
#endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
@@ -402,7 +424,7 @@ trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub;
static trace_func_graph_ent_t __ftrace_graph_entry = ftrace_graph_entry_stub;
/* Try to assign a return stack array on FTRACE_RETSTACK_ALLOC_SIZE tasks. */
-static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list)
+static int alloc_retstack_tasklist(unsigned long **ret_stack_list)
{
int i;
int ret = 0;
@@ -410,10 +432,7 @@ static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list)
struct task_struct *g, *t;
for (i = 0; i < FTRACE_RETSTACK_ALLOC_SIZE; i++) {
- ret_stack_list[i] =
- kmalloc_array(FTRACE_RETFUNC_DEPTH,
- sizeof(struct ftrace_ret_stack),
- GFP_KERNEL);
+ ret_stack_list[i] = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL);
if (!ret_stack_list[i]) {
start = 0;
end = i;
@@ -431,9 +450,9 @@ static int alloc_retstack_tasklist(struct ftrace_ret_stack **ret_stack_list)
if (t->ret_stack == NULL) {
atomic_set(&t->trace_overrun, 0);
- t->curr_ret_stack = -1;
+ t->curr_ret_stack = 0;
t->curr_ret_depth = -1;
- /* Make sure the tasks see the -1 first: */
+ /* Make sure the tasks see the 0 first: */
smp_wmb();
t->ret_stack = ret_stack_list[start++];
}
@@ -453,6 +472,7 @@ ftrace_graph_probe_sched_switch(void *ignore, bool preempt,
struct task_struct *next,
unsigned int prev_state)
{
+ struct ftrace_ret_stack *ret_stack;
unsigned long long timestamp;
int index;
@@ -477,8 +497,11 @@ ftrace_graph_probe_sched_switch(void *ignore, bool preempt,
*/
timestamp -= next->ftrace_timestamp;
- for (index = next->curr_ret_stack; index >= 0; index--)
- next->ret_stack[index].calltime += timestamp;
+ for (index = next->curr_ret_stack - FGRAPH_RET_INDEX; index >= 0; ) {
+ ret_stack = RET_STACK(next, index);
+ ret_stack->calltime += timestamp;
+ index -= FGRAPH_RET_INDEX;
+ }
}
static int ftrace_graph_entry_test(struct ftrace_graph_ent *trace)
@@ -521,10 +544,10 @@ void update_function_graph_func(void)
ftrace_graph_entry = __ftrace_graph_entry;
}
-static DEFINE_PER_CPU(struct ftrace_ret_stack *, idle_ret_stack);
+static DEFINE_PER_CPU(unsigned long *, idle_ret_stack);
static void
-graph_init_task(struct task_struct *t, struct ftrace_ret_stack *ret_stack)
+graph_init_task(struct task_struct *t, unsigned long *ret_stack)
{
atomic_set(&t->trace_overrun, 0);
t->ftrace_timestamp = 0;
@@ -539,7 +562,7 @@ graph_init_task(struct task_struct *t, struct ftrace_ret_stack *ret_stack)
*/
void ftrace_graph_init_idle_task(struct task_struct *t, int cpu)
{
- t->curr_ret_stack = -1;
+ t->curr_ret_stack = 0;
t->curr_ret_depth = -1;
/*
* The idle task has no parent, it either has its own
@@ -549,14 +572,11 @@ void ftrace_graph_init_idle_task(struct task_struct *t, int cpu)
WARN_ON(t->ret_stack != per_cpu(idle_ret_stack, cpu));
if (ftrace_graph_active) {
- struct ftrace_ret_stack *ret_stack;
+ unsigned long *ret_stack;
ret_stack = per_cpu(idle_ret_stack, cpu);
if (!ret_stack) {
- ret_stack =
- kmalloc_array(FTRACE_RETFUNC_DEPTH,
- sizeof(struct ftrace_ret_stack),
- GFP_KERNEL);
+ ret_stack = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL);
if (!ret_stack)
return;
per_cpu(idle_ret_stack, cpu) = ret_stack;
@@ -570,15 +590,13 @@ void ftrace_graph_init_task(struct task_struct *t)
{
/* Make sure we do not use the parent ret_stack */
t->ret_stack = NULL;
- t->curr_ret_stack = -1;
+ t->curr_ret_stack = 0;
t->curr_ret_depth = -1;
if (ftrace_graph_active) {
- struct ftrace_ret_stack *ret_stack;
+ unsigned long *ret_stack;
- ret_stack = kmalloc_array(FTRACE_RETFUNC_DEPTH,
- sizeof(struct ftrace_ret_stack),
- GFP_KERNEL);
+ ret_stack = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL);
if (!ret_stack)
return;
graph_init_task(t, ret_stack);
@@ -587,7 +605,7 @@ void ftrace_graph_init_task(struct task_struct *t)
void ftrace_graph_exit_task(struct task_struct *t)
{
- struct ftrace_ret_stack *ret_stack = t->ret_stack;
+ unsigned long *ret_stack = t->ret_stack;
t->ret_stack = NULL;
/* NULL must become visible to IRQs before we free it: */
@@ -599,12 +617,10 @@ void ftrace_graph_exit_task(struct task_struct *t)
/* Allocate a return stack for each task */
static int start_graph_tracing(void)
{
- struct ftrace_ret_stack **ret_stack_list;
+ unsigned long **ret_stack_list;
int ret, cpu;
- ret_stack_list = kmalloc_array(FTRACE_RETSTACK_ALLOC_SIZE,
- sizeof(struct ftrace_ret_stack *),
- GFP_KERNEL);
+ ret_stack_list = kmalloc(SHADOW_STACK_SIZE, GFP_KERNEL);
if (!ret_stack_list)
return -ENOMEM;
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 04/34] fgraph: Use BUILD_BUG_ON() to make sure we have structures divisible by long
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (2 preceding siblings ...)
2023-12-18 13:12 ` [PATCH v5 03/34] function_graph: Convert ret_stack to a series of longs Masami Hiramatsu (Google)
@ 2023-12-18 13:12 ` Masami Hiramatsu (Google)
2023-12-18 13:12 ` [PATCH v5 05/34] function_graph: Add an array structure that will allow multiple callbacks Masami Hiramatsu (Google)
` (29 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:12 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
Instead of using "ALIGN()", use BUILD_BUG_ON() as the structures should
always be divisible by sizeof(long).
Link: http://lkml.kernel.org/r/20190524111144.GI2589@hirez.programming.kicks-ass.net
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
kernel/trace/fgraph.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 30edeb6d4aa9..837daf929d2a 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -26,10 +26,9 @@
#endif
#define FGRAPH_RET_SIZE sizeof(struct ftrace_ret_stack)
-#define FGRAPH_RET_INDEX (ALIGN(FGRAPH_RET_SIZE, sizeof(long)) / sizeof(long))
+#define FGRAPH_RET_INDEX (FGRAPH_RET_SIZE / sizeof(long))
#define SHADOW_STACK_SIZE (PAGE_SIZE)
-#define SHADOW_STACK_INDEX \
- (ALIGN(SHADOW_STACK_SIZE, sizeof(long)) / sizeof(long))
+#define SHADOW_STACK_INDEX (SHADOW_STACK_SIZE / sizeof(long))
/* Leave on a buffer at the end */
#define SHADOW_STACK_MAX_INDEX (SHADOW_STACK_INDEX - FGRAPH_RET_INDEX)
@@ -91,6 +90,8 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
if (!current->ret_stack)
return -EBUSY;
+ BUILD_BUG_ON(SHADOW_STACK_SIZE % sizeof(long));
+
/*
* We must make sure the ret_stack is tested before we read
* anything else.
@@ -325,6 +326,8 @@ ftrace_graph_get_ret_stack(struct task_struct *task, int idx)
{
int index = task->curr_ret_stack;
+ BUILD_BUG_ON(FGRAPH_RET_SIZE % sizeof(long));
+
index -= FGRAPH_RET_INDEX * (idx + 1);
if (index < 0)
return NULL;
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 05/34] function_graph: Add an array structure that will allow multiple callbacks
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (3 preceding siblings ...)
2023-12-18 13:12 ` [PATCH v5 04/34] fgraph: Use BUILD_BUG_ON() to make sure we have structures divisible by long Masami Hiramatsu (Google)
@ 2023-12-18 13:12 ` Masami Hiramatsu (Google)
2023-12-18 13:12 ` [PATCH v5 06/34] function_graph: Allow multiple users to attach to function graph Masami Hiramatsu (Google)
` (28 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:12 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
Add an array structure that will eventually allow the function graph tracer
to have up to 16 simultaneous callbacks attached. It's an array of 16
fgraph_ops pointers, that is assigned when one is registered. On entry of a
function the entry of the first item in the array is called, and if it
returns zero, then the callback returns non zero if it wants the return
callback to be called on exit of the function.
The array will simplify the process of having more than one callback
attached to the same function, as its index into the array can be stored on
the shadow stack. We need to only save the index, because this will allow
the fgraph_ops to be freed before the function returns (which may happen if
the function call schedule for a long time).
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v2:
- Remove unneeded brace.
---
kernel/trace/fgraph.c | 114 +++++++++++++++++++++++++++++++++++--------------
1 file changed, 81 insertions(+), 33 deletions(-)
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 837daf929d2a..86df3ca6964f 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -39,6 +39,11 @@
DEFINE_STATIC_KEY_FALSE(kill_ftrace_graph);
int ftrace_graph_active;
+static int fgraph_array_cnt;
+#define FGRAPH_ARRAY_SIZE 16
+
+static struct fgraph_ops *fgraph_array[FGRAPH_ARRAY_SIZE];
+
/* Both enabled by default (can be cleared by function_graph tracer flags */
static bool fgraph_sleep_time = true;
@@ -62,6 +67,20 @@ int __weak ftrace_disable_ftrace_graph_caller(void)
}
#endif
+int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
+{
+ return 0;
+}
+
+static void ftrace_graph_ret_stub(struct ftrace_graph_ret *trace)
+{
+}
+
+static struct fgraph_ops fgraph_stub = {
+ .entryfunc = ftrace_graph_entry_stub,
+ .retfunc = ftrace_graph_ret_stub,
+};
+
/**
* ftrace_graph_stop - set to permanently disable function graph tracing
*
@@ -159,7 +178,7 @@ int function_graph_enter(unsigned long ret, unsigned long func,
goto out;
/* Only trace if the calling function expects to */
- if (!ftrace_graph_entry(&trace))
+ if (!fgraph_array[0]->entryfunc(&trace))
goto out_ret;
return 0;
@@ -274,7 +293,7 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
trace.retval = fgraph_ret_regs_return_value(ret_regs);
#endif
trace.rettime = trace_clock_local();
- ftrace_graph_return(&trace);
+ fgraph_array[0]->retfunc(&trace);
/*
* The ftrace_graph_return() may still access the current
* ret_stack structure, we need to make sure the update of
@@ -410,11 +429,6 @@ void ftrace_graph_sleep_time_control(bool enable)
fgraph_sleep_time = enable;
}
-int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
-{
- return 0;
-}
-
/*
* Simply points to ftrace_stub, but with the proper protocol.
* Defined by the linker script in linux/vmlinux.lds.h
@@ -652,37 +666,54 @@ static int start_graph_tracing(void)
int register_ftrace_graph(struct fgraph_ops *gops)
{
int ret = 0;
+ int i;
mutex_lock(&ftrace_lock);
- /* we currently allow only one tracer registered at a time */
- if (ftrace_graph_active) {
+ if (!fgraph_array[0]) {
+ /* The array must always have real data on it */
+ for (i = 0; i < FGRAPH_ARRAY_SIZE; i++)
+ fgraph_array[i] = &fgraph_stub;
+ }
+
+ /* Look for an available spot */
+ for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) {
+ if (fgraph_array[i] == &fgraph_stub)
+ break;
+ }
+ if (i >= FGRAPH_ARRAY_SIZE) {
ret = -EBUSY;
goto out;
}
- register_pm_notifier(&ftrace_suspend_notifier);
+ fgraph_array[i] = gops;
+ if (i + 1 > fgraph_array_cnt)
+ fgraph_array_cnt = i + 1;
ftrace_graph_active++;
- ret = start_graph_tracing();
- if (ret) {
- ftrace_graph_active--;
- goto out;
- }
- ftrace_graph_return = gops->retfunc;
+ if (ftrace_graph_active == 1) {
+ register_pm_notifier(&ftrace_suspend_notifier);
+ ret = start_graph_tracing();
+ if (ret) {
+ ftrace_graph_active--;
+ goto out;
+ }
+
+ ftrace_graph_return = gops->retfunc;
- /*
- * Update the indirect function to the entryfunc, and the
- * function that gets called to the entry_test first. Then
- * call the update fgraph entry function to determine if
- * the entryfunc should be called directly or not.
- */
- __ftrace_graph_entry = gops->entryfunc;
- ftrace_graph_entry = ftrace_graph_entry_test;
- update_function_graph_func();
+ /*
+ * Update the indirect function to the entryfunc, and the
+ * function that gets called to the entry_test first. Then
+ * call the update fgraph entry function to determine if
+ * the entryfunc should be called directly or not.
+ */
+ __ftrace_graph_entry = gops->entryfunc;
+ ftrace_graph_entry = ftrace_graph_entry_test;
+ update_function_graph_func();
- ret = ftrace_startup(&graph_ops, FTRACE_START_FUNC_RET);
+ ret = ftrace_startup(&graph_ops, FTRACE_START_FUNC_RET);
+ }
out:
mutex_unlock(&ftrace_lock);
return ret;
@@ -690,19 +721,36 @@ int register_ftrace_graph(struct fgraph_ops *gops)
void unregister_ftrace_graph(struct fgraph_ops *gops)
{
+ int i;
+
mutex_lock(&ftrace_lock);
if (unlikely(!ftrace_graph_active))
goto out;
- ftrace_graph_active--;
- ftrace_graph_return = ftrace_stub_graph;
- ftrace_graph_entry = ftrace_graph_entry_stub;
- __ftrace_graph_entry = ftrace_graph_entry_stub;
- ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET);
- unregister_pm_notifier(&ftrace_suspend_notifier);
- unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
+ for (i = 0; i < fgraph_array_cnt; i++)
+ if (gops == fgraph_array[i])
+ break;
+ if (i >= fgraph_array_cnt)
+ goto out;
+ fgraph_array[i] = &fgraph_stub;
+ if (i + 1 == fgraph_array_cnt) {
+ for (; i >= 0; i--)
+ if (fgraph_array[i] != &fgraph_stub)
+ break;
+ fgraph_array_cnt = i + 1;
+ }
+
+ ftrace_graph_active--;
+ if (!ftrace_graph_active) {
+ ftrace_graph_return = ftrace_stub_graph;
+ ftrace_graph_entry = ftrace_graph_entry_stub;
+ __ftrace_graph_entry = ftrace_graph_entry_stub;
+ ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET);
+ unregister_pm_notifier(&ftrace_suspend_notifier);
+ unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
+ }
out:
mutex_unlock(&ftrace_lock);
}
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 06/34] function_graph: Allow multiple users to attach to function graph
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (4 preceding siblings ...)
2023-12-18 13:12 ` [PATCH v5 05/34] function_graph: Add an array structure that will allow multiple callbacks Masami Hiramatsu (Google)
@ 2023-12-18 13:12 ` Masami Hiramatsu (Google)
2023-12-19 13:23 ` Jiri Olsa
2023-12-18 13:12 ` [PATCH v5 07/34] function_graph: Remove logic around ftrace_graph_entry and return Masami Hiramatsu (Google)
` (27 subsequent siblings)
33 siblings, 1 reply; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:12 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
Allow for multiple users to attach to function graph tracer at the same
time. Only 16 simultaneous users can attach to the tracer. This is because
there's an array that stores the pointers to the attached fgraph_ops. When
a function being traced is entered, each of the ftrace_ops entryfunc is
called and if it returns non zero, its index into the array will be added
to the shadow stack.
On exit of the function being traced, the shadow stack will contain the
indexes of the ftrace_ops on the array that want their retfunc to be
called.
Because a function may sleep for a long time (if a task sleeps itself),
the return of the function may be literally days later. If the ftrace_ops
is removed, its place on the array is replaced with a ftrace_ops that
contains the stub functions and that will be called when the function
finally returns.
If another ftrace_ops is added that happens to get the same index into the
array, its return function may be called. But that's actually the way
things current work with the old function graph tracer. If one tracer is
removed and another is added, the new one will get the return calls of the
function traced by the previous one, thus this is not a regression. This
can be fixed by adding a counter to each time the array item is updated and
save that on the shadow stack as well, such that it won't be called if the
index saved does not match the index on the array.
Note, being able to filter functions when both are called is not completely
handled yet, but that shouldn't be too hard to manage.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v2:
- Check return value of the ftrace_pop_return_trace() instead of 'ret'
since 'ret' is set to the address of panic().
- Fix typo and make lines shorter than 76 chars in description.
---
kernel/trace/fgraph.c | 332 +++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 280 insertions(+), 52 deletions(-)
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 86df3ca6964f..8aba93be11b2 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -27,23 +27,144 @@
#define FGRAPH_RET_SIZE sizeof(struct ftrace_ret_stack)
#define FGRAPH_RET_INDEX (FGRAPH_RET_SIZE / sizeof(long))
+
+/*
+ * On entry to a function (via function_graph_enter()), a new ftrace_ret_stack
+ * is allocated on the task's ret_stack, then each fgraph_ops on the
+ * fgraph_array[]'s entryfunc is called and if that returns non-zero, the
+ * index into the fgraph_array[] for that fgraph_ops is added to the ret_stack.
+ * As the associated ftrace_ret_stack saved for those fgraph_ops needs to
+ * be found, the index to it is also added to the ret_stack along with the
+ * index of the fgraph_array[] to each fgraph_ops that needs their retfunc
+ * called.
+ *
+ * The top of the ret_stack (when not empty) will always have a reference
+ * to the last ftrace_ret_stack saved. All references to the
+ * ftrace_ret_stack has the format of:
+ *
+ * bits: 0 - 13 Index in words from the previous ftrace_ret_stack
+ * bits: 14 - 15 Type of storage
+ * 0 - reserved
+ * 1 - fgraph_array index
+ * For fgraph_array_index:
+ * bits: 16 - 23 The fgraph_ops fgraph_array index
+ *
+ * That is, at the end of function_graph_enter, if the first and forth
+ * fgraph_ops on the fgraph_array[] (index 0 and 3) needs their retfunc called
+ * on the return of the function being traced, this is what will be on the
+ * task's shadow ret_stack: (the stack grows upward)
+ *
+ * | | <- task->curr_ret_stack
+ * +----------------------------------+
+ * | (3 << FGRAPH_ARRAY_SHIFT)|(2) | ( 3 for index of fourth fgraph_ops)
+ * +----------------------------------+
+ * | (0 << FGRAPH_ARRAY_SHIFT)|(1) | ( 0 for index of first fgraph_ops)
+ * +----------------------------------+
+ * | struct ftrace_ret_stack |
+ * | (stores the saved ret pointer) |
+ * +----------------------------------+
+ * | (X) | (N) | ( N words away from previous ret_stack)
+ * | |
+ *
+ * If a backtrace is required, and the real return pointer needs to be
+ * fetched, then it looks at the task's curr_ret_stack index, if it
+ * is greater than zero, it would subtact one, and then mask the value
+ * on the ret_stack by FGRAPH_RET_INDEX_MASK and subtract FGRAPH_RET_INDEX
+ * from that, to get the index of the ftrace_ret_stack structure stored
+ * on the shadow stack.
+ */
+
+#define FGRAPH_RET_INDEX_SIZE 14
+#define FGRAPH_RET_INDEX_MASK ((1 << FGRAPH_RET_INDEX_SIZE) - 1)
+
+
+#define FGRAPH_TYPE_SIZE 2
+#define FGRAPH_TYPE_MASK ((1 << FGRAPH_TYPE_SIZE) - 1)
+#define FGRAPH_TYPE_SHIFT FGRAPH_RET_INDEX_SIZE
+
+enum {
+ FGRAPH_TYPE_RESERVED = 0,
+ FGRAPH_TYPE_ARRAY = 1,
+};
+
+#define FGRAPH_ARRAY_SIZE 16
+#define FGRAPH_ARRAY_MASK ((1 << FGRAPH_ARRAY_SIZE) - 1)
+#define FGRAPH_ARRAY_SHIFT (FGRAPH_TYPE_SHIFT + FGRAPH_TYPE_SIZE)
+
+/* Currently the max stack index can't be more than register callers */
+#define FGRAPH_MAX_INDEX FGRAPH_ARRAY_SIZE
+
+#define FGRAPH_FRAME_SIZE (FGRAPH_RET_SIZE + FGRAPH_ARRAY_SIZE * (sizeof(long)))
+#define FGRAPH_FRAME_INDEX (ALIGN(FGRAPH_FRAME_SIZE, \
+ sizeof(long)) / sizeof(long))
#define SHADOW_STACK_SIZE (PAGE_SIZE)
#define SHADOW_STACK_INDEX (SHADOW_STACK_SIZE / sizeof(long))
/* Leave on a buffer at the end */
-#define SHADOW_STACK_MAX_INDEX (SHADOW_STACK_INDEX - FGRAPH_RET_INDEX)
+#define SHADOW_STACK_MAX_INDEX (SHADOW_STACK_INDEX - (FGRAPH_RET_INDEX + 1))
#define RET_STACK(t, index) ((struct ftrace_ret_stack *)(&(t)->ret_stack[index]))
-#define RET_STACK_INC(c) ({ c += FGRAPH_RET_INDEX; })
-#define RET_STACK_DEC(c) ({ c -= FGRAPH_RET_INDEX; })
DEFINE_STATIC_KEY_FALSE(kill_ftrace_graph);
int ftrace_graph_active;
static int fgraph_array_cnt;
-#define FGRAPH_ARRAY_SIZE 16
static struct fgraph_ops *fgraph_array[FGRAPH_ARRAY_SIZE];
+static inline int get_ret_stack_index(struct task_struct *t, int offset)
+{
+ return current->ret_stack[offset] & FGRAPH_RET_INDEX_MASK;
+}
+
+static inline int get_fgraph_type(struct task_struct *t, int offset)
+{
+ return (current->ret_stack[offset] >> FGRAPH_TYPE_SHIFT) &
+ FGRAPH_TYPE_MASK;
+}
+
+static inline int get_fgraph_array(struct task_struct *t, int offset)
+{
+ return (current->ret_stack[offset] >> FGRAPH_ARRAY_SHIFT) &
+ FGRAPH_ARRAY_MASK;
+}
+
+/*
+ * @offset: The index into @t->ret_stack to find the ret_stack entry
+ * @index: Where to place the index into @t->ret_stack of that entry
+ *
+ * Calling this with:
+ *
+ * offset = task->curr_ret_stack;
+ * do {
+ * ret_stack = get_ret_stack(task, offset, &offset);
+ * } while (ret_stack);
+ *
+ * Will iterate through all the ret_stack entries from curr_ret_stack
+ * down to the first one.
+ */
+static inline struct ftrace_ret_stack *
+get_ret_stack(struct task_struct *t, int offset, int *index)
+{
+ int idx;
+
+ BUILD_BUG_ON(FGRAPH_RET_SIZE % sizeof(long));
+
+ if (offset <= 0)
+ return NULL;
+
+ idx = get_ret_stack_index(t, offset - 1);
+
+ if (idx <= 0 || idx > FGRAPH_MAX_INDEX)
+ return NULL;
+
+ offset -= idx + FGRAPH_RET_INDEX;
+ if (offset < 0)
+ return NULL;
+
+ *index = offset;
+ return RET_STACK(t, offset);
+}
+
/* Both enabled by default (can be cleared by function_graph tracer flags */
static bool fgraph_sleep_time = true;
@@ -126,9 +247,34 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
calltime = trace_clock_local();
index = current->curr_ret_stack;
- RET_STACK_INC(current->curr_ret_stack);
+ /* ret offset = 1 ; type = reserved */
+ current->ret_stack[index + FGRAPH_RET_INDEX] = 1;
ret_stack = RET_STACK(current, index);
+ ret_stack->ret = ret;
+ /*
+ * The unwinders expect curr_ret_stack to point to either zero
+ * or an index where to find the next ret_stack. Even though the
+ * ret stack might be bogus, we want to write the ret and the
+ * index to find the ret_stack before we increment the stack point.
+ * If an interrupt comes in now before we increment the curr_ret_stack
+ * it may blow away what we wrote. But that's fine, because the
+ * index will still be correct (even though the 'ret' won't be).
+ * What we worry about is the index being correct after we increment
+ * the curr_ret_stack and before we update that index, as if an
+ * interrupt comes in and does an unwind stack dump, it will need
+ * at least a correct index!
+ */
barrier();
+ current->curr_ret_stack += FGRAPH_RET_INDEX + 1;
+ /*
+ * This next barrier is to ensure that an interrupt coming in
+ * will not corrupt what we are about to write.
+ */
+ barrier();
+
+ /* Still keep it reserved even if an interrupt came in */
+ current->ret_stack[index + FGRAPH_RET_INDEX] = 1;
+
ret_stack->ret = ret;
ret_stack->func = func;
ret_stack->calltime = calltime;
@@ -159,6 +305,12 @@ int function_graph_enter(unsigned long ret, unsigned long func,
unsigned long frame_pointer, unsigned long *retp)
{
struct ftrace_graph_ent trace;
+ int offset;
+ int start;
+ int type;
+ int val;
+ int cnt = 0;
+ int i;
#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
/*
@@ -177,38 +329,87 @@ int function_graph_enter(unsigned long ret, unsigned long func,
if (ftrace_push_return_trace(ret, func, frame_pointer, retp))
goto out;
- /* Only trace if the calling function expects to */
- if (!fgraph_array[0]->entryfunc(&trace))
+ /* Use start for the distance to ret_stack (skipping over reserve) */
+ start = offset = current->curr_ret_stack - 2;
+
+ for (i = 0; i < fgraph_array_cnt; i++) {
+ struct fgraph_ops *gops = fgraph_array[i];
+
+ if (gops == &fgraph_stub)
+ continue;
+
+ if ((offset == start) &&
+ (current->curr_ret_stack >= SHADOW_STACK_INDEX - 1)) {
+ atomic_inc(¤t->trace_overrun);
+ break;
+ }
+ if (fgraph_array[i]->entryfunc(&trace)) {
+ offset = current->curr_ret_stack;
+ /* Check the top level stored word */
+ type = get_fgraph_type(current, offset - 1);
+
+ val = (i << FGRAPH_ARRAY_SHIFT) |
+ (FGRAPH_TYPE_ARRAY << FGRAPH_TYPE_SHIFT) |
+ ((offset - start) - 1);
+
+ /* We can reuse the top word if it is reserved */
+ if (type == FGRAPH_TYPE_RESERVED) {
+ current->ret_stack[offset - 1] = val;
+ cnt++;
+ continue;
+ }
+ val++;
+
+ current->ret_stack[offset] = val;
+ /*
+ * Write the value before we increment, so that
+ * if an interrupt comes in after we increment
+ * it will still see the value and skip over
+ * this.
+ */
+ barrier();
+ current->curr_ret_stack++;
+ /*
+ * Have to write again, in case an interrupt
+ * came in before the increment and after we
+ * wrote the value.
+ */
+ barrier();
+ current->ret_stack[offset] = val;
+ cnt++;
+ }
+ }
+
+ if (!cnt)
goto out_ret;
return 0;
out_ret:
- RET_STACK_DEC(current->curr_ret_stack);
+ current->curr_ret_stack -= FGRAPH_RET_INDEX + 1;
out:
current->curr_ret_depth--;
return -EBUSY;
}
/* Retrieve a function return address to the trace stack on thread info.*/
-static void
+static struct ftrace_ret_stack *
ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
unsigned long frame_pointer)
{
struct ftrace_ret_stack *ret_stack;
int index;
- index = current->curr_ret_stack;
- RET_STACK_DEC(index);
+ ret_stack = get_ret_stack(current, current->curr_ret_stack, &index);
- if (unlikely(index < 0 || index > SHADOW_STACK_MAX_INDEX)) {
+ if (unlikely(!ret_stack)) {
ftrace_graph_stop();
- WARN_ON(1);
+ WARN(1, "Bad function graph ret_stack pointer: %d",
+ current->curr_ret_stack);
/* Might as well panic, otherwise we have no where to go */
*ret = (unsigned long)panic;
- return;
+ return NULL;
}
- ret_stack = RET_STACK(current, index);
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
/*
* The arch may choose to record the frame pointer used
@@ -228,12 +429,12 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
ftrace_graph_stop();
WARN(1, "Bad frame pointer: expected %lx, received %lx\n"
" from func %ps return to %lx\n",
- current->ret_stack[index].fp,
+ ret_stack->fp,
frame_pointer,
(void *)ret_stack->func,
ret_stack->ret);
*ret = (unsigned long)panic;
- return;
+ return NULL;
}
#endif
@@ -241,13 +442,15 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
trace->func = ret_stack->func;
trace->calltime = ret_stack->calltime;
trace->overrun = atomic_read(¤t->trace_overrun);
- trace->depth = current->curr_ret_depth--;
+ trace->depth = current->curr_ret_depth;
/*
* We still want to trace interrupts coming in if
* max_depth is set to 1. Make sure the decrement is
* seen before ftrace_graph_return.
*/
barrier();
+
+ return ret_stack;
}
/*
@@ -285,30 +488,47 @@ struct fgraph_ret_regs;
static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs,
unsigned long frame_pointer)
{
+ struct ftrace_ret_stack *ret_stack;
struct ftrace_graph_ret trace;
unsigned long ret;
+ int offset;
+ int index;
+ int idx;
+ int i;
+
+ ret_stack = ftrace_pop_return_trace(&trace, &ret, frame_pointer);
+
+ if (unlikely(!ret_stack)) {
+ ftrace_graph_stop();
+ WARN_ON(1);
+ /* Might as well panic. What else to do? */
+ return (unsigned long)panic;
+ }
- ftrace_pop_return_trace(&trace, &ret, frame_pointer);
+ trace.rettime = trace_clock_local();
#ifdef CONFIG_FUNCTION_GRAPH_RETVAL
trace.retval = fgraph_ret_regs_return_value(ret_regs);
#endif
- trace.rettime = trace_clock_local();
- fgraph_array[0]->retfunc(&trace);
+
+ offset = current->curr_ret_stack - 1;
+ index = get_ret_stack_index(current, offset);
+
+ /* index has to be at least one! Optimize for it */
+ i = 0;
+ do {
+ idx = get_fgraph_array(current, offset - i);
+ fgraph_array[idx]->retfunc(&trace);
+ i++;
+ } while (i < index);
+
/*
* The ftrace_graph_return() may still access the current
* ret_stack structure, we need to make sure the update of
* curr_ret_stack is after that.
*/
barrier();
- RET_STACK_DEC(current->curr_ret_stack);
-
- if (unlikely(!ret)) {
- ftrace_graph_stop();
- WARN_ON(1);
- /* Might as well panic. What else to do? */
- ret = (unsigned long)panic;
- }
-
+ current->curr_ret_stack -= index + FGRAPH_RET_INDEX;
+ current->curr_ret_depth--;
return ret;
}
@@ -343,15 +563,17 @@ unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
struct ftrace_ret_stack *
ftrace_graph_get_ret_stack(struct task_struct *task, int idx)
{
+ struct ftrace_ret_stack *ret_stack = NULL;
int index = task->curr_ret_stack;
- BUILD_BUG_ON(FGRAPH_RET_SIZE % sizeof(long));
-
- index -= FGRAPH_RET_INDEX * (idx + 1);
if (index < 0)
return NULL;
- return RET_STACK(task, index);
+ do {
+ ret_stack = get_ret_stack(task, index, &index);
+ } while (ret_stack && --idx >= 0);
+
+ return ret_stack;
}
/**
@@ -374,16 +596,15 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
unsigned long ret, unsigned long *retp)
{
struct ftrace_ret_stack *ret_stack;
- int index = task->curr_ret_stack;
- int i;
+ int i = task->curr_ret_stack;
if (ret != (unsigned long)dereference_kernel_function_descriptor(return_to_handler))
return ret;
- RET_STACK_DEC(index);
-
- for (i = index; i >= 0; RET_STACK_DEC(i)) {
- ret_stack = RET_STACK(task, i);
+ while (i > 0) {
+ ret_stack = get_ret_stack(current, i, &i);
+ if (!ret_stack)
+ break;
if (ret_stack->retp == retp)
return ret_stack->ret;
}
@@ -394,21 +615,26 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
unsigned long ret, unsigned long *retp)
{
- int task_idx;
+ struct ftrace_ret_stack *ret_stack;
+ int task_idx = task->curr_ret_stack;
+ int i;
if (ret != (unsigned long)dereference_kernel_function_descriptor(return_to_handler))
return ret;
- task_idx = task->curr_ret_stack;
- RET_STACK_DEC(task_idx);
-
- if (!task->ret_stack || task_idx < *idx)
+ if (!idx)
return ret;
- task_idx -= *idx;
- RET_STACK_INC(*idx);
+ i = *idx;
+ do {
+ ret_stack = get_ret_stack(task, task_idx, &task_idx);
+ i--;
+ } while (i >= 0 && ret_stack);
+
+ if (ret_stack)
+ return ret_stack->ret;
- return RET_STACK(task, task_idx);
+ return ret;
}
#endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
@@ -514,10 +740,10 @@ ftrace_graph_probe_sched_switch(void *ignore, bool preempt,
*/
timestamp -= next->ftrace_timestamp;
- for (index = next->curr_ret_stack - FGRAPH_RET_INDEX; index >= 0; ) {
- ret_stack = RET_STACK(next, index);
- ret_stack->calltime += timestamp;
- index -= FGRAPH_RET_INDEX;
+ for (index = next->curr_ret_stack; index > 0; ) {
+ ret_stack = get_ret_stack(next, index, &index);
+ if (ret_stack)
+ ret_stack->calltime += timestamp;
}
}
@@ -568,6 +794,8 @@ graph_init_task(struct task_struct *t, unsigned long *ret_stack)
{
atomic_set(&t->trace_overrun, 0);
t->ftrace_timestamp = 0;
+ t->curr_ret_stack = 0;
+ t->curr_ret_depth = -1;
/* make curr_ret_stack visible before we add the ret_stack */
smp_wmb();
t->ret_stack = ret_stack;
^ permalink raw reply related [flat|nested] 56+ messages in thread* Re: [PATCH v5 06/34] function_graph: Allow multiple users to attach to function graph
2023-12-18 13:12 ` [PATCH v5 06/34] function_graph: Allow multiple users to attach to function graph Masami Hiramatsu (Google)
@ 2023-12-19 13:23 ` Jiri Olsa
2023-12-19 15:45 ` Masami Hiramatsu
0 siblings, 1 reply; 56+ messages in thread
From: Jiri Olsa @ 2023-12-19 13:23 UTC (permalink / raw)
To: Masami Hiramatsu (Google)
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Arnaldo Carvalho de Melo, Daniel Borkmann,
Alan Maguire, Mark Rutland, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Mon, Dec 18, 2023 at 10:12:45PM +0900, Masami Hiramatsu (Google) wrote:
SNIP
> /* Both enabled by default (can be cleared by function_graph tracer flags */
> static bool fgraph_sleep_time = true;
>
> @@ -126,9 +247,34 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> calltime = trace_clock_local();
>
> index = current->curr_ret_stack;
> - RET_STACK_INC(current->curr_ret_stack);
> + /* ret offset = 1 ; type = reserved */
> + current->ret_stack[index + FGRAPH_RET_INDEX] = 1;
> ret_stack = RET_STACK(current, index);
> + ret_stack->ret = ret;
> + /*
> + * The unwinders expect curr_ret_stack to point to either zero
> + * or an index where to find the next ret_stack. Even though the
> + * ret stack might be bogus, we want to write the ret and the
> + * index to find the ret_stack before we increment the stack point.
> + * If an interrupt comes in now before we increment the curr_ret_stack
> + * it may blow away what we wrote. But that's fine, because the
> + * index will still be correct (even though the 'ret' won't be).
> + * What we worry about is the index being correct after we increment
> + * the curr_ret_stack and before we update that index, as if an
> + * interrupt comes in and does an unwind stack dump, it will need
> + * at least a correct index!
> + */
> barrier();
> + current->curr_ret_stack += FGRAPH_RET_INDEX + 1;
> + /*
> + * This next barrier is to ensure that an interrupt coming in
> + * will not corrupt what we are about to write.
> + */
> + barrier();
> +
> + /* Still keep it reserved even if an interrupt came in */
> + current->ret_stack[index + FGRAPH_RET_INDEX] = 1;
seems like this was set already few lines above?
jirka
> +
> ret_stack->ret = ret;
> ret_stack->func = func;
> ret_stack->calltime = calltime;
> @@ -159,6 +305,12 @@ int function_graph_enter(unsigned long ret, unsigned long func,
> unsigned long frame_pointer, unsigned long *retp)
> {
> struct ftrace_graph_ent trace;
> + int offset;
> + int start;
> + int type;
> + int val;
> + int cnt = 0;
> + int i;
>
> #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
> /*
SNIP
^ permalink raw reply [flat|nested] 56+ messages in thread* Re: [PATCH v5 06/34] function_graph: Allow multiple users to attach to function graph
2023-12-19 13:23 ` Jiri Olsa
@ 2023-12-19 15:45 ` Masami Hiramatsu
2023-12-26 15:24 ` Masami Hiramatsu
0 siblings, 1 reply; 56+ messages in thread
From: Masami Hiramatsu @ 2023-12-19 15:45 UTC (permalink / raw)
To: Jiri Olsa
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Arnaldo Carvalho de Melo, Daniel Borkmann,
Alan Maguire, Mark Rutland, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Tue, 19 Dec 2023 14:23:37 +0100
Jiri Olsa <olsajiri@gmail.com> wrote:
> On Mon, Dec 18, 2023 at 10:12:45PM +0900, Masami Hiramatsu (Google) wrote:
>
> SNIP
>
> > /* Both enabled by default (can be cleared by function_graph tracer flags */
> > static bool fgraph_sleep_time = true;
> >
> > @@ -126,9 +247,34 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> > calltime = trace_clock_local();
> >
> > index = current->curr_ret_stack;
> > - RET_STACK_INC(current->curr_ret_stack);
> > + /* ret offset = 1 ; type = reserved */
> > + current->ret_stack[index + FGRAPH_RET_INDEX] = 1;
> > ret_stack = RET_STACK(current, index);
> > + ret_stack->ret = ret;
> > + /*
> > + * The unwinders expect curr_ret_stack to point to either zero
> > + * or an index where to find the next ret_stack. Even though the
> > + * ret stack might be bogus, we want to write the ret and the
> > + * index to find the ret_stack before we increment the stack point.
> > + * If an interrupt comes in now before we increment the curr_ret_stack
> > + * it may blow away what we wrote. But that's fine, because the
> > + * index will still be correct (even though the 'ret' won't be).
> > + * What we worry about is the index being correct after we increment
> > + * the curr_ret_stack and before we update that index, as if an
> > + * interrupt comes in and does an unwind stack dump, it will need
> > + * at least a correct index!
> > + */
> > barrier();
> > + current->curr_ret_stack += FGRAPH_RET_INDEX + 1;
> > + /*
> > + * This next barrier is to ensure that an interrupt coming in
> > + * will not corrupt what we are about to write.
> > + */
> > + barrier();
> > +
> > + /* Still keep it reserved even if an interrupt came in */
> > + current->ret_stack[index + FGRAPH_RET_INDEX] = 1;
>
> seems like this was set already few lines above?
Yeah, there is a trick (trap) for interrupts between writes. We can not do
atomically write the last stack entry and increment stack index. But it must
be done for shadow unwinding insinde interrupts. Thus,
(1) write a reserve type entry on the new stack entry
(2) increment curr_ret_stack to the new stack entry
(3) rewrite the new stack entry again
If an interrupt happens between (1) and (2), stack unwinder can find the
correct latest shadow stack frame from the curr_ret_stack. This interrupts
can store their shadow stack so... wait something went wrong.
If the interrupt *overwrites* the shadow stack and (3) recovers it,
if another interrupt before (3), the shadow stack will be corrupted...
OK, I think we need a "rsrv_ret_stack" index. Basically new one will do;
(1) increment rsrv_ret_stack
(2) write a reserve type entry
(3) set curr_ret_stack = rsrv_ret_stack
And before those,
(0) if rsrv_ret_stack != curr_ret_stack, write a reserve type entry at
rsrv_ret_stack for the previous frame (which offset can be read
from curr_ret_stack)
Than it will never be broken.
(of course when decrement curr_ret_stack, rsrv_ret_stack is also decremented)
Thank you,
>
> jirka
>
> > +
> > ret_stack->ret = ret;
> > ret_stack->func = func;
> > ret_stack->calltime = calltime;
> > @@ -159,6 +305,12 @@ int function_graph_enter(unsigned long ret, unsigned long func,
> > unsigned long frame_pointer, unsigned long *retp)
> > {
> > struct ftrace_graph_ent trace;
> > + int offset;
> > + int start;
> > + int type;
> > + int val;
> > + int cnt = 0;
> > + int i;
> >
> > #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
> > /*
>
> SNIP
>
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 56+ messages in thread* Re: [PATCH v5 06/34] function_graph: Allow multiple users to attach to function graph
2023-12-19 15:45 ` Masami Hiramatsu
@ 2023-12-26 15:24 ` Masami Hiramatsu
0 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu @ 2023-12-26 15:24 UTC (permalink / raw)
To: Masami Hiramatsu, Steven Rostedt, Jiri Olsa
Cc: Jiri Olsa, Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Arnaldo Carvalho de Melo, Daniel Borkmann,
Alan Maguire, Mark Rutland, Peter Zijlstra, Thomas Gleixner,
Guo Ren
Hi,
On Wed, 20 Dec 2023 00:45:40 +0900
Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote:
> OK, I think we need a "rsrv_ret_stack" index. Basically new one will do;
>
> (1) increment rsrv_ret_stack
> (2) write a reserve type entry
> (3) set curr_ret_stack = rsrv_ret_stack
>
> And before those,
>
> (0) if rsrv_ret_stack != curr_ret_stack, write a reserve type entry at
> rsrv_ret_stack for the previous frame (which offset can be read
> from curr_ret_stack)
>
> Than it will never be broken.
> (of course when decrement curr_ret_stack, rsrv_ret_stack is also decremented)
>
So here is an additional patch for this issue. I'll make v6 with this.
Thanks,
From 4da1ec7b679052a131ecdeebd2e1a9db767c5c24 Mon Sep 17 00:00:00 2001
From: Masami Hiramatsu <mhiramat@kernel.org>
Date: Wed, 27 Dec 2023 00:09:09 +0900
Subject: [PATCH] function_graph: Improve push operation for several interrupts
Improve push and data reserve operation on the shadow stack for
several sequencial interrupts.
To push a ret_stack or data entry on the shadow stack, we need to
prepare an index (offset) entry before updating the stack pointer
(curr_ret_stack) so that unwinder from interrupts can find the
next return address from the shadow stack. Currently we do write index,
update the curr_ret_stack, and rewrite it again. But that is not enough
for the case if two interrupts happens and the first one breaks it.
For example,
1. write reserved index entry at ret_stack[new_index - 1] and ret addr.
2. interrupt comes.
2.1. push new index and ret addr on ret_stack.
2.2. pop it. (corrupt entries on new_index - 1)
3. return from interrupt.
4. update curr_ret_stack = new_index
5. interrupt comes again.
5.1. unwind <------ may not work.
To avoid this issue, this introduces a new rsrv_ret_stack stack
reservation pointer and a new push code (slow path) to commit
previous reserved code forcibly.
0. update rsrv_ret_stack = new_index.
1. write reserved index entry at ret_stack[new_index - 1] and ret addr.
2. interrupt comes.
2.0. if rsrv_ret_stack != curr_ret_stack, add reserved index
entry on ret_stack[rsrv_ret_stack - 1] to point the previous
ret_stack pointed by ret_stack[curr_ret_stack - 1]. and
update curr_ret_stack = rsrv_ret_stack.
2.1. push new index and ret addr on ret_stack.
2.2. pop it. (corrupt entries on new_index - 1)
3. return from interrupt.
4. update curr_ret_stack = new_index
5. interrupt comes again.
5.1. unwind works, because curr_ret_stack points the previously
saved ret_stack.
5.2. this can do push/pop operations too.
6. return from interrupt.
7. rewrite reserved index entry at ret_stack[new_index] again.
This maybe a bit heavier but safer.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
include/linux/sched.h | 1 +
kernel/trace/fgraph.c | 133 ++++++++++++++++++++++++++++++------------
2 files changed, 97 insertions(+), 37 deletions(-)
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4dab30f00211..fda551e1aade 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1387,6 +1387,7 @@ struct task_struct {
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
/* Index of current stored address in ret_stack: */
int curr_ret_stack;
+ int rsrv_ret_stack;
int curr_ret_depth;
/* Stack of return addresses for return function tracing: */
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 47f389834b50..bf7a6eebff75 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -298,31 +298,47 @@ void *fgraph_reserve_data(int idx, int size_bytes)
unsigned long val;
void *data;
int curr_ret_stack = current->curr_ret_stack;
+ int rsrv_ret_stack = current->rsrv_ret_stack;
int data_size;
if (size_bytes > FGRAPH_MAX_DATA_SIZE)
return NULL;
+ /*
+ * Since this API is used after pushing ret_stack, curr_ret_stack
+ * should be synchronized with rsrv_ret_stack.
+ */
+ if (WARN_ON_ONCE(curr_ret_stack != rsrv_ret_stack))
+ return NULL;
+
/* Convert to number of longs + data word */
data_size = DIV_ROUND_UP(size_bytes, sizeof(long));
val = get_fgraph_entry(current, curr_ret_stack - 1);
data = ¤t->ret_stack[curr_ret_stack];
- curr_ret_stack += data_size + 1;
- if (unlikely(curr_ret_stack >= SHADOW_STACK_MAX_INDEX))
+ rsrv_ret_stack += data_size + 1;
+ if (unlikely(rsrv_ret_stack >= SHADOW_STACK_MAX_INDEX))
return NULL;
val = make_fgraph_data(idx, data_size, __get_index(val) + data_size + 1);
- /* Set the last word to be reserved */
- current->ret_stack[curr_ret_stack - 1] = val;
-
- /* Make sure interrupts see this */
+ /* Extend the reserved-ret_stack at first */
+ current->rsrv_ret_stack = rsrv_ret_stack;
+ /* And sync with interrupts, to see the new rsrv_ret_stack */
+ barrier();
+ /*
+ * The same reason as the push, this entry must be here before updating
+ * the curr_ret_stack. But any interrupt comes before updating
+ * curr_ret_stack, it may commit it with different reserve entry.
+ * Thus we need to write the data entry after update the curr_ret_stack
+ * again. And these operations must be ordered.
+ */
+ current->ret_stack[rsrv_ret_stack - 1] = val;
barrier();
- current->curr_ret_stack = curr_ret_stack;
- /* Again sync with interrupts, and reset reserve */
- current->ret_stack[curr_ret_stack - 1] = val;
+ current->curr_ret_stack = rsrv_ret_stack;
+ barrier();
+ current->ret_stack[rsrv_ret_stack - 1] = val;
return data;
}
@@ -403,7 +419,16 @@ get_ret_stack(struct task_struct *t, int offset, int *index)
return NULL;
idx = get_ret_stack_index(t, --offset);
- if (WARN_ON_ONCE(idx <= 0 || idx > offset))
+ /*
+ * This can happen if an interrupt comes just before the first push
+ * increments the curr_ret_stack, and that interrupt pushes another
+ * entry. In that case, the frist push is forcibly committed with a
+ * reserved entry which points -1 stack index.
+ */
+ if (unlikely(idx > offset))
+ return NULL;
+
+ if (WARN_ON_ONCE(idx <= 0))
return NULL;
offset -= idx;
@@ -473,7 +498,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
struct ftrace_ret_stack *ret_stack;
unsigned long long calltime;
unsigned long val;
- int index;
+ int index, rindex;
if (unlikely(ftrace_graph_is_dead()))
return -EBUSY;
@@ -481,17 +506,37 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
if (!current->ret_stack)
return -EBUSY;
- /*
- * At first, check whether the previous fgraph callback is pushed by
- * the fgraph on the same function entry.
- * But if @func is the self tail-call function, we also need to ensure
- * the ret_stack is not for the previous call by checking whether the
- * bit of @fgraph_idx is set or not.
- */
- ret_stack = get_ret_stack(current, current->curr_ret_stack, &index);
- if (ret_stack && ret_stack->func == func &&
- !is_fgraph_index_set(current, index + FGRAPH_RET_INDEX, fgraph_idx))
- return index + FGRAPH_RET_INDEX;
+ index = READ_ONCE(current->curr_ret_stack);
+ rindex = READ_ONCE(current->rsrv_ret_stack);
+ if (unlikely(index != rindex)) {
+ /*
+ * This interrupts during pushing operation. Commit previous
+ * push temporarily with reserved entry.
+ */
+ if (unlikely(index <= 0))
+ /* This will make ret_stack[index - 1] points -1 */
+ val = rindex - index;
+ else
+ val = get_ret_stack_index(current, index - 1) +
+ rindex - index;
+ current->ret_stack[rindex - 1] = val;
+ /* Forcibly commit it */
+ current->curr_ret_stack = index = rindex;
+ } else {
+ /*
+ * At first, check whether the previous fgraph callback is pushed by
+ * the fgraph on the same function entry.
+ * But if @func is the self tail-call function, we also need to ensure
+ * the ret_stack is not for the previous call by checking whether the
+ * bit of @fgraph_idx is set or not.
+ */
+ ret_stack = get_ret_stack(current, index, &index);
+ if (ret_stack && ret_stack->func == func &&
+ !is_fgraph_index_set(current, index + FGRAPH_RET_INDEX, fgraph_idx))
+ return index + FGRAPH_RET_INDEX;
+ /* Since get_ret_stack() writes 'index', so recover it. */
+ index = rindex;
+ }
val = (FGRAPH_TYPE_RESERVED << FGRAPH_TYPE_SHIFT) | FGRAPH_RET_INDEX;
@@ -511,38 +556,45 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
calltime = trace_clock_local();
- index = READ_ONCE(current->curr_ret_stack);
ret_stack = RET_STACK(current, index);
index += FGRAPH_RET_INDEX;
- /* ret offset = FGRAPH_RET_INDEX ; type = reserved */
+ /*
+ * At first, reserve the ret_stack. Beyond this point, any interrupt
+ * will only overwrite ret_stack[index] by a reserved entry which points
+ * the previous ret_stack or -1.
+ */
+ current->rsrv_ret_stack = index + 1;
+ /* And ensure that the following happens after reserved */
+ barrier();
+
current->ret_stack[index] = val;
ret_stack->ret = ret;
/*
* The unwinders expect curr_ret_stack to point to either zero
- * or an index where to find the next ret_stack. Even though the
- * ret stack might be bogus, we want to write the ret and the
- * index to find the ret_stack before we increment the stack point.
- * If an interrupt comes in now before we increment the curr_ret_stack
- * it may blow away what we wrote. But that's fine, because the
- * index will still be correct (even though the 'ret' won't be).
- * What we worry about is the index being correct after we increment
- * the curr_ret_stack and before we update that index, as if an
- * interrupt comes in and does an unwind stack dump, it will need
- * at least a correct index!
+ * or an index where to find the next ret_stack which has actual ret
+ * address. Thus we want to write the ret and the index to find the
+ * ret_stack before we increment the curr_ret_stack.
*/
barrier();
current->curr_ret_stack = index + 1;
/*
+ * There are two possibilities here.
+ * - More than one interrupts push/pop their entry between update
+ * rsrv_ret_stack and curr_ret_stack. In this case, curr_ret_stack
+ * is already equal to the rsrv_ret_stack and
+ * current->ret_stack[index] is overwritten by reserved entry which
+ * points the previous ret_stack. But ret_stack->ret is not.
+ * - Or, no interrupts push/pop. So current->ret_stack[index] keeps
+ * its value.
* This next barrier is to ensure that an interrupt coming in
- * will not corrupt what we are about to write.
+ * will not overwrite what we are about to write anymore.
*/
barrier();
- /* Still keep it reserved even if an interrupt came in */
+ /* Rewrite the entry again in case it was overwritten. */
current->ret_stack[index] = val;
- ret_stack->ret = ret;
ret_stack->func = func;
ret_stack->calltime = calltime;
#ifdef HAVE_FUNCTION_GRAPH_FP_TEST
@@ -636,6 +688,7 @@ int function_graph_enter_regs(unsigned long ret, unsigned long func,
return 0;
out_ret:
current->curr_ret_stack -= FGRAPH_RET_INDEX + 1;
+ current->rsrv_ret_stack = current->curr_ret_stack;
out:
current->curr_ret_depth--;
return -EBUSY;
@@ -680,6 +733,7 @@ int function_graph_enter_ops(unsigned long ret, unsigned long func,
if (type == FGRAPH_TYPE_RESERVED) {
current->curr_ret_stack -= FGRAPH_RET_INDEX + 1;
+ current->rsrv_ret_stack = current->curr_ret_stack;
current->curr_ret_depth--;
}
return -EBUSY;
@@ -840,6 +894,7 @@ static unsigned long __ftrace_return_to_handler(struct ftrace_regs *fregs,
*/
barrier();
current->curr_ret_stack = index - FGRAPH_RET_INDEX;
+ current->rsrv_ret_stack = current->curr_ret_stack;
current->curr_ret_depth--;
return ret;
@@ -1031,6 +1086,7 @@ static int alloc_retstack_tasklist(unsigned long **ret_stack_list)
atomic_set(&t->trace_overrun, 0);
ret_stack_init_task_vars(ret_stack_list[start]);
t->curr_ret_stack = 0;
+ t->rsrv_ret_stack = 0;
t->curr_ret_depth = -1;
/* Make sure the tasks see the 0 first: */
smp_wmb();
@@ -1093,6 +1149,7 @@ graph_init_task(struct task_struct *t, unsigned long *ret_stack)
ret_stack_init_task_vars(ret_stack);
t->ftrace_timestamp = 0;
t->curr_ret_stack = 0;
+ t->rsrv_ret_stack = 0;
t->curr_ret_depth = -1;
/* make curr_ret_stack visible before we add the ret_stack */
smp_wmb();
@@ -1106,6 +1163,7 @@ graph_init_task(struct task_struct *t, unsigned long *ret_stack)
void ftrace_graph_init_idle_task(struct task_struct *t, int cpu)
{
t->curr_ret_stack = 0;
+ t->rsrv_ret_stack = 0;
t->curr_ret_depth = -1;
/*
* The idle task has no parent, it either has its own
@@ -1134,6 +1192,7 @@ void ftrace_graph_init_task(struct task_struct *t)
/* Make sure we do not use the parent ret_stack */
t->ret_stack = NULL;
t->curr_ret_stack = 0;
+ t->rsrv_ret_stack = 0;
t->curr_ret_depth = -1;
if (ftrace_graph_active) {
--
2.43.0.472.g3155946c3a-goog
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply related [flat|nested] 56+ messages in thread
* [PATCH v5 07/34] function_graph: Remove logic around ftrace_graph_entry and return
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (5 preceding siblings ...)
2023-12-18 13:12 ` [PATCH v5 06/34] function_graph: Allow multiple users to attach to function graph Masami Hiramatsu (Google)
@ 2023-12-18 13:12 ` Masami Hiramatsu (Google)
2023-12-18 13:13 ` [PATCH v5 08/34] ftrace/function_graph: Pass fgraph_ops to function graph callbacks Masami Hiramatsu (Google)
` (26 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:12 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
The function pointers ftrace_graph_entry and ftrace_graph_return are no
longer called via the function_graph tracer. Instead, an array structure is
now used that will allow for multiple users of the function_graph
infrastructure. The variables are still used by the architecture code for
non dynamic ftrace configs, where a test is made against them to see if
they point to the default stub function or not. This is how the static
function tracing knows to call into the function graph tracer
infrastructure or not.
Two new stub functions are made. entry_run() and return_run(). The
ftrace_graph_entry and ftrace_graph_return are set to them respectively
when the function graph tracer is enabled, and this will trigger the
architecture specific function graph code to be executed.
This also requires checking the global_ops hash for all calls into the
function_graph tracer.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v2:
- Fix typo and make lines shorter than 76 chars in the description.
- Remove unneeded return from return_run() function.
---
kernel/trace/fgraph.c | 71 +++++++++++-----------------------------
kernel/trace/ftrace.c | 2 -
kernel/trace/ftrace_internal.h | 2 -
3 files changed, 19 insertions(+), 56 deletions(-)
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 8aba93be11b2..97a9ffb8bb4c 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -128,6 +128,17 @@ static inline int get_fgraph_array(struct task_struct *t, int offset)
FGRAPH_ARRAY_MASK;
}
+/* ftrace_graph_entry set to this to tell some archs to run function graph */
+static int entry_run(struct ftrace_graph_ent *trace)
+{
+ return 0;
+}
+
+/* ftrace_graph_return set to this to tell some archs to run function graph */
+static void return_run(struct ftrace_graph_ret *trace)
+{
+}
+
/*
* @offset: The index into @t->ret_stack to find the ret_stack entry
* @index: Where to place the index into @t->ret_stack of that entry
@@ -323,6 +334,10 @@ int function_graph_enter(unsigned long ret, unsigned long func,
ftrace_find_rec_direct(ret - MCOUNT_INSN_SIZE))
return -EBUSY;
#endif
+
+ if (!ftrace_ops_test(&global_ops, func, NULL))
+ return -EBUSY;
+
trace.func = func;
trace.depth = ++current->curr_ret_depth;
@@ -664,7 +679,6 @@ extern void ftrace_stub_graph(struct ftrace_graph_ret *);
/* The callbacks that hook a function */
trace_func_graph_ret_t ftrace_graph_return = ftrace_stub_graph;
trace_func_graph_ent_t ftrace_graph_entry = ftrace_graph_entry_stub;
-static trace_func_graph_ent_t __ftrace_graph_entry = ftrace_graph_entry_stub;
/* Try to assign a return stack array on FTRACE_RETSTACK_ALLOC_SIZE tasks. */
static int alloc_retstack_tasklist(unsigned long **ret_stack_list)
@@ -747,46 +761,6 @@ ftrace_graph_probe_sched_switch(void *ignore, bool preempt,
}
}
-static int ftrace_graph_entry_test(struct ftrace_graph_ent *trace)
-{
- if (!ftrace_ops_test(&global_ops, trace->func, NULL))
- return 0;
- return __ftrace_graph_entry(trace);
-}
-
-/*
- * The function graph tracer should only trace the functions defined
- * by set_ftrace_filter and set_ftrace_notrace. If another function
- * tracer ops is registered, the graph tracer requires testing the
- * function against the global ops, and not just trace any function
- * that any ftrace_ops registered.
- */
-void update_function_graph_func(void)
-{
- struct ftrace_ops *op;
- bool do_test = false;
-
- /*
- * The graph and global ops share the same set of functions
- * to test. If any other ops is on the list, then
- * the graph tracing needs to test if its the function
- * it should call.
- */
- do_for_each_ftrace_op(op, ftrace_ops_list) {
- if (op != &global_ops && op != &graph_ops &&
- op != &ftrace_list_end) {
- do_test = true;
- /* in double loop, break out with goto */
- goto out;
- }
- } while_for_each_ftrace_op(op);
- out:
- if (do_test)
- ftrace_graph_entry = ftrace_graph_entry_test;
- else
- ftrace_graph_entry = __ftrace_graph_entry;
-}
-
static DEFINE_PER_CPU(unsigned long *, idle_ret_stack);
static void
@@ -927,18 +901,12 @@ int register_ftrace_graph(struct fgraph_ops *gops)
ftrace_graph_active--;
goto out;
}
-
- ftrace_graph_return = gops->retfunc;
-
/*
- * Update the indirect function to the entryfunc, and the
- * function that gets called to the entry_test first. Then
- * call the update fgraph entry function to determine if
- * the entryfunc should be called directly or not.
+ * Some archs just test to see if these are not
+ * the default function
*/
- __ftrace_graph_entry = gops->entryfunc;
- ftrace_graph_entry = ftrace_graph_entry_test;
- update_function_graph_func();
+ ftrace_graph_return = return_run;
+ ftrace_graph_entry = entry_run;
ret = ftrace_startup(&graph_ops, FTRACE_START_FUNC_RET);
}
@@ -974,7 +942,6 @@ void unregister_ftrace_graph(struct fgraph_ops *gops)
if (!ftrace_graph_active) {
ftrace_graph_return = ftrace_stub_graph;
ftrace_graph_entry = ftrace_graph_entry_stub;
- __ftrace_graph_entry = ftrace_graph_entry_stub;
ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET);
unregister_pm_notifier(&ftrace_suspend_notifier);
unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 8de8bec5f366..fd64021ec52f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -235,8 +235,6 @@ static void update_ftrace_function(void)
func = ftrace_ops_list_func;
}
- update_function_graph_func();
-
/* If there's no change, then do nothing more here */
if (ftrace_trace_function == func)
return;
diff --git a/kernel/trace/ftrace_internal.h b/kernel/trace/ftrace_internal.h
index 5012c04f92c0..19eddcb91584 100644
--- a/kernel/trace/ftrace_internal.h
+++ b/kernel/trace/ftrace_internal.h
@@ -42,10 +42,8 @@ ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
extern int ftrace_graph_active;
-void update_function_graph_func(void);
#else /* !CONFIG_FUNCTION_GRAPH_TRACER */
# define ftrace_graph_active 0
-static inline void update_function_graph_func(void) { }
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
#else /* !CONFIG_FUNCTION_TRACER */
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 08/34] ftrace/function_graph: Pass fgraph_ops to function graph callbacks
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (6 preceding siblings ...)
2023-12-18 13:12 ` [PATCH v5 07/34] function_graph: Remove logic around ftrace_graph_entry and return Masami Hiramatsu (Google)
@ 2023-12-18 13:13 ` Masami Hiramatsu (Google)
2023-12-18 13:13 ` [PATCH v5 09/34] ftrace: Allow function_graph tracer to be enabled in instances Masami Hiramatsu (Google)
` (25 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:13 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
Pass the fgraph_ops structure to the function graph callbacks. This will
allow callbacks to add a descriptor to a fgraph_ops private field that wil
be added in the future and use it for the callbacks. This will be useful
when more than one callback can be registered to the function graph tracer.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v2:
- cleanup to set argument name on function prototype.
---
include/linux/ftrace.h | 10 +++++++---
kernel/trace/fgraph.c | 16 +++++++++-------
kernel/trace/ftrace.c | 6 ++++--
kernel/trace/trace.h | 4 ++--
kernel/trace/trace_functions_graph.c | 11 +++++++----
kernel/trace/trace_irqsoff.c | 6 ++++--
kernel/trace/trace_sched_wakeup.c | 6 ++++--
kernel/trace/trace_selftest.c | 5 +++--
8 files changed, 40 insertions(+), 24 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 8b48fc621ea0..bc216cdc742d 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1055,11 +1055,15 @@ struct ftrace_graph_ret {
unsigned long long rettime;
} __packed;
+struct fgraph_ops;
+
/* Type of the callback handlers for tracing function graph*/
-typedef void (*trace_func_graph_ret_t)(struct ftrace_graph_ret *); /* return */
-typedef int (*trace_func_graph_ent_t)(struct ftrace_graph_ent *); /* entry */
+typedef void (*trace_func_graph_ret_t)(struct ftrace_graph_ret *,
+ struct fgraph_ops *); /* return */
+typedef int (*trace_func_graph_ent_t)(struct ftrace_graph_ent *,
+ struct fgraph_ops *); /* entry */
-extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace);
+extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 97a9ffb8bb4c..62c35d6d95f9 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -129,13 +129,13 @@ static inline int get_fgraph_array(struct task_struct *t, int offset)
}
/* ftrace_graph_entry set to this to tell some archs to run function graph */
-static int entry_run(struct ftrace_graph_ent *trace)
+static int entry_run(struct ftrace_graph_ent *trace, struct fgraph_ops *ops)
{
return 0;
}
/* ftrace_graph_return set to this to tell some archs to run function graph */
-static void return_run(struct ftrace_graph_ret *trace)
+static void return_run(struct ftrace_graph_ret *trace, struct fgraph_ops *ops)
{
}
@@ -199,12 +199,14 @@ int __weak ftrace_disable_ftrace_graph_caller(void)
}
#endif
-int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace)
+int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace,
+ struct fgraph_ops *gops)
{
return 0;
}
-static void ftrace_graph_ret_stub(struct ftrace_graph_ret *trace)
+static void ftrace_graph_ret_stub(struct ftrace_graph_ret *trace,
+ struct fgraph_ops *gops)
{
}
@@ -358,7 +360,7 @@ int function_graph_enter(unsigned long ret, unsigned long func,
atomic_inc(¤t->trace_overrun);
break;
}
- if (fgraph_array[i]->entryfunc(&trace)) {
+ if (fgraph_array[i]->entryfunc(&trace, fgraph_array[i])) {
offset = current->curr_ret_stack;
/* Check the top level stored word */
type = get_fgraph_type(current, offset - 1);
@@ -532,7 +534,7 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
i = 0;
do {
idx = get_fgraph_array(current, offset - i);
- fgraph_array[idx]->retfunc(&trace);
+ fgraph_array[idx]->retfunc(&trace, fgraph_array[idx]);
i++;
} while (i < index);
@@ -674,7 +676,7 @@ void ftrace_graph_sleep_time_control(bool enable)
* Simply points to ftrace_stub, but with the proper protocol.
* Defined by the linker script in linux/vmlinux.lds.h
*/
-extern void ftrace_stub_graph(struct ftrace_graph_ret *);
+void ftrace_stub_graph(struct ftrace_graph_ret *trace, struct fgraph_ops *gops);
/* The callbacks that hook a function */
trace_func_graph_ret_t ftrace_graph_return = ftrace_stub_graph;
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index fd64021ec52f..7ff5c454622a 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -815,7 +815,8 @@ void ftrace_graph_graph_time_control(bool enable)
fgraph_graph_time = enable;
}
-static int profile_graph_entry(struct ftrace_graph_ent *trace)
+static int profile_graph_entry(struct ftrace_graph_ent *trace,
+ struct fgraph_ops *gops)
{
struct ftrace_ret_stack *ret_stack;
@@ -832,7 +833,8 @@ static int profile_graph_entry(struct ftrace_graph_ent *trace)
return 1;
}
-static void profile_graph_return(struct ftrace_graph_ret *trace)
+static void profile_graph_return(struct ftrace_graph_ret *trace,
+ struct fgraph_ops *gops)
{
struct ftrace_ret_stack *ret_stack;
struct ftrace_profile_stat *stat;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index b7f4ea25a194..d72d5e81f48a 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -675,8 +675,8 @@ void trace_latency_header(struct seq_file *m);
void trace_default_header(struct seq_file *m);
void print_trace_header(struct seq_file *m, struct trace_iterator *iter);
-void trace_graph_return(struct ftrace_graph_ret *trace);
-int trace_graph_entry(struct ftrace_graph_ent *trace);
+void trace_graph_return(struct ftrace_graph_ret *trace, struct fgraph_ops *gops);
+int trace_graph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);
void set_graph_array(struct trace_array *tr);
void tracing_start_cmdline_record(void);
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index c35fbaab2a47..b7b142b65299 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -129,7 +129,8 @@ static inline int ftrace_graph_ignore_irqs(void)
return in_hardirq();
}
-int trace_graph_entry(struct ftrace_graph_ent *trace)
+int trace_graph_entry(struct ftrace_graph_ent *trace,
+ struct fgraph_ops *gops)
{
struct trace_array *tr = graph_array;
struct trace_array_cpu *data;
@@ -238,7 +239,8 @@ void __trace_graph_return(struct trace_array *tr,
trace_buffer_unlock_commit_nostack(buffer, event);
}
-void trace_graph_return(struct ftrace_graph_ret *trace)
+void trace_graph_return(struct ftrace_graph_ret *trace,
+ struct fgraph_ops *gops)
{
struct trace_array *tr = graph_array;
struct trace_array_cpu *data;
@@ -275,7 +277,8 @@ void set_graph_array(struct trace_array *tr)
smp_mb();
}
-static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
+static void trace_graph_thresh_return(struct ftrace_graph_ret *trace,
+ struct fgraph_ops *gops)
{
ftrace_graph_addr_finish(trace);
@@ -288,7 +291,7 @@ static void trace_graph_thresh_return(struct ftrace_graph_ret *trace)
(trace->rettime - trace->calltime < tracing_thresh))
return;
else
- trace_graph_return(trace);
+ trace_graph_return(trace, gops);
}
static struct fgraph_ops funcgraph_thresh_ops = {
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index ba37f768e2f2..5478f4c4f708 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -175,7 +175,8 @@ static int irqsoff_display_graph(struct trace_array *tr, int set)
return start_irqsoff_tracer(irqsoff_trace, set);
}
-static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
+static int irqsoff_graph_entry(struct ftrace_graph_ent *trace,
+ struct fgraph_ops *gops)
{
struct trace_array *tr = irqsoff_trace;
struct trace_array_cpu *data;
@@ -205,7 +206,8 @@ static int irqsoff_graph_entry(struct ftrace_graph_ent *trace)
return ret;
}
-static void irqsoff_graph_return(struct ftrace_graph_ret *trace)
+static void irqsoff_graph_return(struct ftrace_graph_ret *trace,
+ struct fgraph_ops *gops)
{
struct trace_array *tr = irqsoff_trace;
struct trace_array_cpu *data;
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 0469a04a355f..49bcc812652c 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -112,7 +112,8 @@ static int wakeup_display_graph(struct trace_array *tr, int set)
return start_func_tracer(tr, set);
}
-static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
+static int wakeup_graph_entry(struct ftrace_graph_ent *trace,
+ struct fgraph_ops *gops)
{
struct trace_array *tr = wakeup_trace;
struct trace_array_cpu *data;
@@ -141,7 +142,8 @@ static int wakeup_graph_entry(struct ftrace_graph_ent *trace)
return ret;
}
-static void wakeup_graph_return(struct ftrace_graph_ret *trace)
+static void wakeup_graph_return(struct ftrace_graph_ret *trace,
+ struct fgraph_ops *gops)
{
struct trace_array *tr = wakeup_trace;
struct trace_array_cpu *data;
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 529590499b1f..914331d8242c 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -762,7 +762,8 @@ trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
static unsigned int graph_hang_thresh;
/* Wrap the real function entry probe to avoid possible hanging */
-static int trace_graph_entry_watchdog(struct ftrace_graph_ent *trace)
+static int trace_graph_entry_watchdog(struct ftrace_graph_ent *trace,
+ struct fgraph_ops *gops)
{
/* This is harmlessly racy, we want to approximately detect a hang */
if (unlikely(++graph_hang_thresh > GRAPH_MAX_FUNC_TEST)) {
@@ -776,7 +777,7 @@ static int trace_graph_entry_watchdog(struct ftrace_graph_ent *trace)
return 0;
}
- return trace_graph_entry(trace);
+ return trace_graph_entry(trace, gops);
}
static struct fgraph_ops fgraph_ops __initdata = {
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 09/34] ftrace: Allow function_graph tracer to be enabled in instances
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (7 preceding siblings ...)
2023-12-18 13:13 ` [PATCH v5 08/34] ftrace/function_graph: Pass fgraph_ops to function graph callbacks Masami Hiramatsu (Google)
@ 2023-12-18 13:13 ` Masami Hiramatsu (Google)
2023-12-18 13:13 ` [PATCH v5 10/34] ftrace: Allow ftrace startup flags exist without dynamic ftrace Masami Hiramatsu (Google)
` (24 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:13 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
Now that function graph tracing can handle more than one user, allow it to
be enabled in the ftrace instances. Note, the filtering of the functions is
still joined by the top level set_ftrace_filter and friends, as well as the
graph and nograph files.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v2:
- Fix to remove set_graph_array() completely.
---
include/linux/ftrace.h | 1 +
kernel/trace/ftrace.c | 1 +
kernel/trace/trace.h | 13 ++++++-
kernel/trace/trace_functions.c | 8 ++++
kernel/trace/trace_functions_graph.c | 65 +++++++++++++++++++++-------------
kernel/trace/trace_selftest.c | 4 +-
6 files changed, 64 insertions(+), 28 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index bc216cdc742d..0955baccbb87 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1070,6 +1070,7 @@ extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph
struct fgraph_ops {
trace_func_graph_ent_t entryfunc;
trace_func_graph_ret_t retfunc;
+ void *private;
};
/*
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 7ff5c454622a..83fbfb7b48f8 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -7319,6 +7319,7 @@ __init void ftrace_init_global_array_ops(struct trace_array *tr)
tr->ops = &global_ops;
tr->ops->private = tr;
ftrace_init_trace_array(tr);
+ init_array_fgraph_ops(tr);
}
void ftrace_init_array_ops(struct trace_array *tr, ftrace_func_t func)
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index d72d5e81f48a..16948c0ed00a 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -395,6 +395,9 @@ struct trace_array {
struct ftrace_ops *ops;
struct trace_pid_list __rcu *function_pids;
struct trace_pid_list __rcu *function_no_pids;
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+ struct fgraph_ops *gops;
+#endif
#ifdef CONFIG_DYNAMIC_FTRACE
/* All of these are protected by the ftrace_lock */
struct list_head func_probes;
@@ -677,7 +680,6 @@ void print_trace_header(struct seq_file *m, struct trace_iterator *iter);
void trace_graph_return(struct ftrace_graph_ret *trace, struct fgraph_ops *gops);
int trace_graph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);
-void set_graph_array(struct trace_array *tr);
void tracing_start_cmdline_record(void);
void tracing_stop_cmdline_record(void);
@@ -888,6 +890,9 @@ extern int __trace_graph_entry(struct trace_array *tr,
extern void __trace_graph_return(struct trace_array *tr,
struct ftrace_graph_ret *trace,
unsigned int trace_ctx);
+extern void init_array_fgraph_ops(struct trace_array *tr);
+extern int allocate_fgraph_ops(struct trace_array *tr);
+extern void free_fgraph_ops(struct trace_array *tr);
#ifdef CONFIG_DYNAMIC_FTRACE
extern struct ftrace_hash __rcu *ftrace_graph_hash;
@@ -1000,6 +1005,12 @@ print_graph_function_flags(struct trace_iterator *iter, u32 flags)
{
return TRACE_TYPE_UNHANDLED;
}
+static inline void init_array_fgraph_ops(struct trace_array *tr) { }
+static inline int allocate_fgraph_ops(struct trace_array *tr)
+{
+ return 0;
+}
+static inline void free_fgraph_ops(struct trace_array *tr) { }
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
extern struct list_head ftrace_pids;
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 9f1bfbe105e8..8e8da0d0ee52 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -80,6 +80,7 @@ void ftrace_free_ftrace_ops(struct trace_array *tr)
int ftrace_create_function_files(struct trace_array *tr,
struct dentry *parent)
{
+ int ret;
/*
* The top level array uses the "global_ops", and the files are
* created on boot up.
@@ -90,6 +91,12 @@ int ftrace_create_function_files(struct trace_array *tr,
if (!tr->ops)
return -EINVAL;
+ ret = allocate_fgraph_ops(tr);
+ if (ret) {
+ kfree(tr->ops);
+ return ret;
+ }
+
ftrace_create_filter_files(tr->ops, parent);
return 0;
@@ -99,6 +106,7 @@ void ftrace_destroy_function_files(struct trace_array *tr)
{
ftrace_destroy_filter_files(tr->ops);
ftrace_free_ftrace_ops(tr);
+ free_fgraph_ops(tr);
}
static ftrace_func_t select_trace_function(u32 flags_val)
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index b7b142b65299..9ccc904a7703 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -83,8 +83,6 @@ static struct tracer_flags tracer_flags = {
.opts = trace_opts
};
-static struct trace_array *graph_array;
-
/*
* DURATION column is being also used to display IRQ signs,
* following values are used by print_graph_irq and others
@@ -132,7 +130,7 @@ static inline int ftrace_graph_ignore_irqs(void)
int trace_graph_entry(struct ftrace_graph_ent *trace,
struct fgraph_ops *gops)
{
- struct trace_array *tr = graph_array;
+ struct trace_array *tr = gops->private;
struct trace_array_cpu *data;
unsigned long flags;
unsigned int trace_ctx;
@@ -242,7 +240,7 @@ void __trace_graph_return(struct trace_array *tr,
void trace_graph_return(struct ftrace_graph_ret *trace,
struct fgraph_ops *gops)
{
- struct trace_array *tr = graph_array;
+ struct trace_array *tr = gops->private;
struct trace_array_cpu *data;
unsigned long flags;
unsigned int trace_ctx;
@@ -268,15 +266,6 @@ void trace_graph_return(struct ftrace_graph_ret *trace,
local_irq_restore(flags);
}
-void set_graph_array(struct trace_array *tr)
-{
- graph_array = tr;
-
- /* Make graph_array visible before we start tracing */
-
- smp_mb();
-}
-
static void trace_graph_thresh_return(struct ftrace_graph_ret *trace,
struct fgraph_ops *gops)
{
@@ -294,25 +283,53 @@ static void trace_graph_thresh_return(struct ftrace_graph_ret *trace,
trace_graph_return(trace, gops);
}
-static struct fgraph_ops funcgraph_thresh_ops = {
- .entryfunc = &trace_graph_entry,
- .retfunc = &trace_graph_thresh_return,
-};
-
static struct fgraph_ops funcgraph_ops = {
.entryfunc = &trace_graph_entry,
.retfunc = &trace_graph_return,
};
+int allocate_fgraph_ops(struct trace_array *tr)
+{
+ struct fgraph_ops *gops;
+
+ gops = kzalloc(sizeof(*gops), GFP_KERNEL);
+ if (!gops)
+ return -ENOMEM;
+
+ gops->entryfunc = &trace_graph_entry;
+ gops->retfunc = &trace_graph_return;
+
+ tr->gops = gops;
+ gops->private = tr;
+ return 0;
+}
+
+void free_fgraph_ops(struct trace_array *tr)
+{
+ kfree(tr->gops);
+}
+
+__init void init_array_fgraph_ops(struct trace_array *tr)
+{
+ tr->gops = &funcgraph_ops;
+ funcgraph_ops.private = tr;
+}
+
static int graph_trace_init(struct trace_array *tr)
{
int ret;
- set_graph_array(tr);
+ tr->gops->entryfunc = trace_graph_entry;
+
if (tracing_thresh)
- ret = register_ftrace_graph(&funcgraph_thresh_ops);
+ tr->gops->retfunc = trace_graph_thresh_return;
else
- ret = register_ftrace_graph(&funcgraph_ops);
+ tr->gops->retfunc = trace_graph_return;
+
+ /* Make gops functions are visible before we start tracing */
+ smp_mb();
+
+ ret = register_ftrace_graph(tr->gops);
if (ret)
return ret;
tracing_start_cmdline_record();
@@ -323,10 +340,7 @@ static int graph_trace_init(struct trace_array *tr)
static void graph_trace_reset(struct trace_array *tr)
{
tracing_stop_cmdline_record();
- if (tracing_thresh)
- unregister_ftrace_graph(&funcgraph_thresh_ops);
- else
- unregister_ftrace_graph(&funcgraph_ops);
+ unregister_ftrace_graph(tr->gops);
}
static int graph_trace_update_thresh(struct trace_array *tr)
@@ -1365,6 +1379,7 @@ static struct tracer graph_trace __tracer_data = {
.print_header = print_graph_headers,
.flags = &tracer_flags,
.set_flag = func_graph_set_flag,
+ .allow_instances = true,
#ifdef CONFIG_FTRACE_SELFTEST
.selftest = trace_selftest_startup_function_graph,
#endif
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index 914331d8242c..f0758afa2f7d 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -813,7 +813,7 @@ trace_selftest_startup_function_graph(struct tracer *trace,
* to detect and recover from possible hangs
*/
tracing_reset_online_cpus(&tr->array_buffer);
- set_graph_array(tr);
+ fgraph_ops.private = tr;
ret = register_ftrace_graph(&fgraph_ops);
if (ret) {
warn_failed_init_tracer(trace, ret);
@@ -856,7 +856,7 @@ trace_selftest_startup_function_graph(struct tracer *trace,
cond_resched();
tracing_reset_online_cpus(&tr->array_buffer);
- set_graph_array(tr);
+ fgraph_ops.private = tr;
/*
* Some archs *cough*PowerPC*cough* add characters to the
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 10/34] ftrace: Allow ftrace startup flags exist without dynamic ftrace
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (8 preceding siblings ...)
2023-12-18 13:13 ` [PATCH v5 09/34] ftrace: Allow function_graph tracer to be enabled in instances Masami Hiramatsu (Google)
@ 2023-12-18 13:13 ` Masami Hiramatsu (Google)
2023-12-18 13:13 ` [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering Masami Hiramatsu (Google)
` (23 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:13 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
Some of the flags for ftrace_startup() may be exposed even when
CONFIG_DYNAMIC_FTRACE is not configured in. This is fine as the difference
between dynamic ftrace and static ftrace is done within the internals of
ftrace itself. No need to have use cases fail to compile because dynamic
ftrace is disabled.
This change is needed to move some of the logic of what is passed to
ftrace_startup() out of the parameters of ftrace_startup().
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
include/linux/ftrace.h | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 0955baccbb87..7b08169aa51d 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -538,6 +538,15 @@ static inline void stack_tracer_disable(void) { }
static inline void stack_tracer_enable(void) { }
#endif
+enum {
+ FTRACE_UPDATE_CALLS = (1 << 0),
+ FTRACE_DISABLE_CALLS = (1 << 1),
+ FTRACE_UPDATE_TRACE_FUNC = (1 << 2),
+ FTRACE_START_FUNC_RET = (1 << 3),
+ FTRACE_STOP_FUNC_RET = (1 << 4),
+ FTRACE_MAY_SLEEP = (1 << 5),
+};
+
#ifdef CONFIG_DYNAMIC_FTRACE
void ftrace_arch_code_modify_prepare(void);
@@ -632,15 +641,6 @@ void ftrace_set_global_notrace(unsigned char *buf, int len, int reset);
void ftrace_free_filter(struct ftrace_ops *ops);
void ftrace_ops_set_global_filter(struct ftrace_ops *ops);
-enum {
- FTRACE_UPDATE_CALLS = (1 << 0),
- FTRACE_DISABLE_CALLS = (1 << 1),
- FTRACE_UPDATE_TRACE_FUNC = (1 << 2),
- FTRACE_START_FUNC_RET = (1 << 3),
- FTRACE_STOP_FUNC_RET = (1 << 4),
- FTRACE_MAY_SLEEP = (1 << 5),
-};
-
/*
* The FTRACE_UPDATE_* enum is used to pass information back
* from the ftrace_update_record() and ftrace_test_record()
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (9 preceding siblings ...)
2023-12-18 13:13 ` [PATCH v5 10/34] ftrace: Allow ftrace startup flags exist without dynamic ftrace Masami Hiramatsu (Google)
@ 2023-12-18 13:13 ` Masami Hiramatsu (Google)
2023-12-26 0:20 ` Masami Hiramatsu
2024-01-05 17:09 ` Mark Rutland
2023-12-18 13:13 ` [PATCH v5 12/34] function_graph: Use a simple LRU for fgraph_array index number Masami Hiramatsu (Google)
` (22 subsequent siblings)
33 siblings, 2 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:13 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
Allow for instances to have their own ftrace_ops part of the fgraph_ops
that makes the funtion_graph tracer filter on the set_ftrace_filter file
of the instance and not the top instance.
This also change how the function_graph handles multiple instances on the
shadow stack. Previously we use ARRAY type entries to record which one
is enabled, and this makes it a bitmap of the fgraph_array's indexes.
Previous function_graph_enter() expects calling back from
prepare_ftrace_return() function which is called back only once if it is
enabled. But this introduces different ftrace_ops for each fgraph
instance and those are called from ftrace_graph_func() one by one. Thus
we can not loop on the fgraph_array(), and need to reuse the ret_stack
pushed by the previous instance. Finding the ret_stack is easy because
we can check the ret_stack->func. But that is not enough for the self-
recursive tail-call case. Thus fgraph uses the bitmap entry to find it
is already set (this means that entry is for previous tail call).
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v4:
- Simplify get_ret_stack() sanity check and use WARN_ON_ONCE() for
obviously wrong value.
- Do not check ret == return_to_handler but always read the previous
ret_stack in ftrace_push_return_trace() to check it is reusable.
- Set the bit 0 of the bitmap entry always in function_graph_enter()
because it uses bit 0 to check re-usability.
- Fix to ensure the ret_stack entry is bitmap type when checking the
bitmap.
Changes in v3:
- Pass current fgraph_ops to the new entry handler
(function_graph_enter_ops) if fgraph use ftrace.
- Add fgraph_ops::idx in this patch.
- Replace the array type with the bitmap type so that it can record
which fgraph is called.
- Fix some helper function to use passed task_struct instead of current.
- Reduce the ret-index size to 1024 words.
- Make the ret-index directly points the ret_stack.
- Fix ftrace_graph_ret_addr() to handle tail-call case correctly.
Changes in v2:
- Use ftrace_graph_func and FTRACE_OPS_GRAPH_STUB instead of
ftrace_stub and FTRACE_OPS_FL_STUB for new ftrace based fgraph.
---
arch/arm64/kernel/ftrace.c | 19 ++
arch/x86/kernel/ftrace.c | 19 ++
include/linux/ftrace.h | 7 +
kernel/trace/fgraph.c | 369 ++++++++++++++++++++--------------
kernel/trace/ftrace.c | 6 -
kernel/trace/trace.h | 16 +
kernel/trace/trace_functions.c | 2
kernel/trace/trace_functions_graph.c | 8 +
8 files changed, 277 insertions(+), 169 deletions(-)
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index a650f5e11fc5..205937e04ece 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -481,7 +481,24 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs)
{
- prepare_ftrace_return(ip, &fregs->lr, fregs->fp);
+ unsigned long *parent = &fregs->lr;
+ struct fgraph_ops *gops = container_of(op, struct fgraph_ops, ops);
+ int bit;
+
+ if (unlikely(ftrace_graph_is_dead()))
+ return;
+
+ if (unlikely(atomic_read(¤t->tracing_graph_pause)))
+ return;
+
+ bit = ftrace_test_recursion_trylock(ip, *parent);
+ if (bit < 0)
+ return;
+
+ if (!function_graph_enter_ops(*parent, ip, fregs->fp, parent, gops))
+ *parent = (unsigned long)&return_to_handler;
+
+ ftrace_test_recursion_unlock(bit);
}
#else
/*
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 12df54ff0e81..845e29b4254f 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -657,9 +657,24 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs)
{
struct pt_regs *regs = &fregs->regs;
- unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs);
+ unsigned long *parent = (unsigned long *)kernel_stack_pointer(regs);
+ struct fgraph_ops *gops = container_of(op, struct fgraph_ops, ops);
+ int bit;
+
+ if (unlikely(ftrace_graph_is_dead()))
+ return;
+
+ if (unlikely(atomic_read(¤t->tracing_graph_pause)))
+ return;
- prepare_ftrace_return(ip, (unsigned long *)stack, 0);
+ bit = ftrace_test_recursion_trylock(ip, *parent);
+ if (bit < 0)
+ return;
+
+ if (!function_graph_enter_ops(*parent, ip, 0, parent, gops))
+ *parent = (unsigned long)&return_to_handler;
+
+ ftrace_test_recursion_unlock(bit);
}
#endif
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 7b08169aa51d..c431a33fe789 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1070,7 +1070,9 @@ extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph
struct fgraph_ops {
trace_func_graph_ent_t entryfunc;
trace_func_graph_ret_t retfunc;
+ struct ftrace_ops ops; /* for the hash lists */
void *private;
+ int idx;
};
/*
@@ -1104,6 +1106,11 @@ extern int
function_graph_enter(unsigned long ret, unsigned long func,
unsigned long frame_pointer, unsigned long *retp);
+extern int
+function_graph_enter_ops(unsigned long ret, unsigned long func,
+ unsigned long frame_pointer, unsigned long *retp,
+ struct fgraph_ops *gops);
+
struct ftrace_ret_stack *
ftrace_graph_get_ret_stack(struct task_struct *task, int idx);
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 62c35d6d95f9..6f537ebd3ed7 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -7,6 +7,7 @@
*
* Highly modified by Steven Rostedt (VMware).
*/
+#include <linux/bits.h>
#include <linux/jump_label.h>
#include <linux/suspend.h>
#include <linux/ftrace.h>
@@ -17,22 +18,15 @@
#include "ftrace_internal.h"
#include "trace.h"
-#ifdef CONFIG_DYNAMIC_FTRACE
-#define ASSIGN_OPS_HASH(opsname, val) \
- .func_hash = val, \
- .local_hash.regex_lock = __MUTEX_INITIALIZER(opsname.local_hash.regex_lock),
-#else
-#define ASSIGN_OPS_HASH(opsname, val)
-#endif
-
#define FGRAPH_RET_SIZE sizeof(struct ftrace_ret_stack)
#define FGRAPH_RET_INDEX (FGRAPH_RET_SIZE / sizeof(long))
/*
* On entry to a function (via function_graph_enter()), a new ftrace_ret_stack
- * is allocated on the task's ret_stack, then each fgraph_ops on the
- * fgraph_array[]'s entryfunc is called and if that returns non-zero, the
- * index into the fgraph_array[] for that fgraph_ops is added to the ret_stack.
+ * is allocated on the task's ret_stack with indexes entry, then each
+ * fgraph_ops on the fgraph_array[]'s entryfunc is called and if that returns
+ * non-zero, the index into the fgraph_array[] for that fgraph_ops is recorded
+ * on the indexes entry as a bit flag.
* As the associated ftrace_ret_stack saved for those fgraph_ops needs to
* be found, the index to it is also added to the ret_stack along with the
* index of the fgraph_array[] to each fgraph_ops that needs their retfunc
@@ -42,61 +36,59 @@
* to the last ftrace_ret_stack saved. All references to the
* ftrace_ret_stack has the format of:
*
- * bits: 0 - 13 Index in words from the previous ftrace_ret_stack
- * bits: 14 - 15 Type of storage
+ * bits: 0 - 9 offset in words from the previous ftrace_ret_stack
+ * (bitmap type should have FGRAPH_RET_INDEX always)
+ * bits: 10 - 11 Type of storage
* 0 - reserved
- * 1 - fgraph_array index
- * For fgraph_array_index:
- * bits: 16 - 23 The fgraph_ops fgraph_array index
+ * 1 - bitmap of fgraph_array index
+ *
+ * For bitmap of fgraph_array index
+ * bits: 12 - 27 The bitmap of fgraph_ops fgraph_array index
*
* That is, at the end of function_graph_enter, if the first and forth
* fgraph_ops on the fgraph_array[] (index 0 and 3) needs their retfunc called
* on the return of the function being traced, this is what will be on the
* task's shadow ret_stack: (the stack grows upward)
*
- * | | <- task->curr_ret_stack
- * +----------------------------------+
- * | (3 << FGRAPH_ARRAY_SHIFT)|(2) | ( 3 for index of fourth fgraph_ops)
- * +----------------------------------+
- * | (0 << FGRAPH_ARRAY_SHIFT)|(1) | ( 0 for index of first fgraph_ops)
- * +----------------------------------+
- * | struct ftrace_ret_stack |
- * | (stores the saved ret pointer) |
- * +----------------------------------+
- * | (X) | (N) | ( N words away from previous ret_stack)
- * | |
+ * | | <- task->curr_ret_stack
+ * +--------------------------------------------+
+ * | bitmap_type(bitmap:(BIT(3)|BIT(0)), |
+ * | offset:FGRAPH_RET_INDEX) | <- the offset is from here
+ * +--------------------------------------------+
+ * | struct ftrace_ret_stack |
+ * | (stores the saved ret pointer) | <- the offset points here
+ * +--------------------------------------------+
+ * | (X) | (N) | ( N words away from
+ * | | previous ret_stack)
*
* If a backtrace is required, and the real return pointer needs to be
* fetched, then it looks at the task's curr_ret_stack index, if it
- * is greater than zero, it would subtact one, and then mask the value
- * on the ret_stack by FGRAPH_RET_INDEX_MASK and subtract FGRAPH_RET_INDEX
- * from that, to get the index of the ftrace_ret_stack structure stored
- * on the shadow stack.
+ * is greater than zero (reserved, or right before poped), it would mask
+ * the value by FGRAPH_RET_INDEX_MASK to get the offset index of the
+ * ftrace_ret_stack structure stored on the shadow stack.
*/
-#define FGRAPH_RET_INDEX_SIZE 14
-#define FGRAPH_RET_INDEX_MASK ((1 << FGRAPH_RET_INDEX_SIZE) - 1)
-
+#define FGRAPH_RET_INDEX_SIZE 10
+#define FGRAPH_RET_INDEX_MASK GENMASK(FGRAPH_RET_INDEX_SIZE - 1, 0)
#define FGRAPH_TYPE_SIZE 2
-#define FGRAPH_TYPE_MASK ((1 << FGRAPH_TYPE_SIZE) - 1)
+#define FGRAPH_TYPE_MASK GENMASK(FGRAPH_TYPE_SIZE - 1, 0)
#define FGRAPH_TYPE_SHIFT FGRAPH_RET_INDEX_SIZE
enum {
FGRAPH_TYPE_RESERVED = 0,
- FGRAPH_TYPE_ARRAY = 1,
+ FGRAPH_TYPE_BITMAP = 1,
};
-#define FGRAPH_ARRAY_SIZE 16
-#define FGRAPH_ARRAY_MASK ((1 << FGRAPH_ARRAY_SIZE) - 1)
-#define FGRAPH_ARRAY_SHIFT (FGRAPH_TYPE_SHIFT + FGRAPH_TYPE_SIZE)
+#define FGRAPH_INDEX_SIZE 16
+#define FGRAPH_INDEX_MASK GENMASK(FGRAPH_INDEX_SIZE - 1, 0)
+#define FGRAPH_INDEX_SHIFT (FGRAPH_TYPE_SHIFT + FGRAPH_TYPE_SIZE)
/* Currently the max stack index can't be more than register callers */
-#define FGRAPH_MAX_INDEX FGRAPH_ARRAY_SIZE
+#define FGRAPH_MAX_INDEX (FGRAPH_INDEX_SIZE + FGRAPH_RET_INDEX)
+
+#define FGRAPH_ARRAY_SIZE FGRAPH_INDEX_SIZE
-#define FGRAPH_FRAME_SIZE (FGRAPH_RET_SIZE + FGRAPH_ARRAY_SIZE * (sizeof(long)))
-#define FGRAPH_FRAME_INDEX (ALIGN(FGRAPH_FRAME_SIZE, \
- sizeof(long)) / sizeof(long))
#define SHADOW_STACK_SIZE (PAGE_SIZE)
#define SHADOW_STACK_INDEX (SHADOW_STACK_SIZE / sizeof(long))
/* Leave on a buffer at the end */
@@ -113,19 +105,36 @@ static struct fgraph_ops *fgraph_array[FGRAPH_ARRAY_SIZE];
static inline int get_ret_stack_index(struct task_struct *t, int offset)
{
- return current->ret_stack[offset] & FGRAPH_RET_INDEX_MASK;
+ return t->ret_stack[offset] & FGRAPH_RET_INDEX_MASK;
}
static inline int get_fgraph_type(struct task_struct *t, int offset)
{
- return (current->ret_stack[offset] >> FGRAPH_TYPE_SHIFT) &
- FGRAPH_TYPE_MASK;
+ return (t->ret_stack[offset] >> FGRAPH_TYPE_SHIFT) & FGRAPH_TYPE_MASK;
+}
+
+static inline unsigned long
+get_fgraph_index_bitmap(struct task_struct *t, int offset)
+{
+ return (t->ret_stack[offset] >> FGRAPH_INDEX_SHIFT) & FGRAPH_INDEX_MASK;
}
-static inline int get_fgraph_array(struct task_struct *t, int offset)
+static inline void
+set_fgraph_index_bitmap(struct task_struct *t, int offset, unsigned long bitmap)
{
- return (current->ret_stack[offset] >> FGRAPH_ARRAY_SHIFT) &
- FGRAPH_ARRAY_MASK;
+ t->ret_stack[offset] = (bitmap << FGRAPH_INDEX_SHIFT) |
+ (FGRAPH_TYPE_BITMAP << FGRAPH_TYPE_SHIFT) | FGRAPH_RET_INDEX;
+}
+
+static inline bool is_fgraph_index_set(struct task_struct *t, int offset, int idx)
+{
+ return !!(get_fgraph_index_bitmap(t, offset) & BIT(idx));
+}
+
+static inline void
+add_fgraph_index_bitmap(struct task_struct *t, int offset, unsigned long bitmap)
+{
+ t->ret_stack[offset] |= (bitmap << FGRAPH_INDEX_SHIFT);
}
/* ftrace_graph_entry set to this to tell some archs to run function graph */
@@ -160,17 +169,14 @@ get_ret_stack(struct task_struct *t, int offset, int *index)
BUILD_BUG_ON(FGRAPH_RET_SIZE % sizeof(long));
- if (offset <= 0)
+ if (unlikely(offset <= 0))
return NULL;
- idx = get_ret_stack_index(t, offset - 1);
-
- if (idx <= 0 || idx > FGRAPH_MAX_INDEX)
+ idx = get_ret_stack_index(t, --offset);
+ if (WARN_ON_ONCE(idx <= 0 || idx > offset))
return NULL;
- offset -= idx + FGRAPH_RET_INDEX;
- if (offset < 0)
- return NULL;
+ offset -= idx;
*index = offset;
return RET_STACK(t, offset);
@@ -231,10 +237,12 @@ void ftrace_graph_stop(void)
/* Add a function return address to the trace stack on thread info.*/
static int
ftrace_push_return_trace(unsigned long ret, unsigned long func,
- unsigned long frame_pointer, unsigned long *retp)
+ unsigned long frame_pointer, unsigned long *retp,
+ int fgraph_idx)
{
struct ftrace_ret_stack *ret_stack;
unsigned long long calltime;
+ unsigned long val;
int index;
if (unlikely(ftrace_graph_is_dead()))
@@ -243,6 +251,21 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
if (!current->ret_stack)
return -EBUSY;
+ /*
+ * At first, check whether the previous fgraph callback is pushed by
+ * the fgraph on the same function entry.
+ * But if @func is the self tail-call function, we also need to ensure
+ * the ret_stack is not for the previous call by checking whether the
+ * bit of @fgraph_idx is set or not.
+ */
+ ret_stack = get_ret_stack(current, current->curr_ret_stack, &index);
+ if (ret_stack && ret_stack->func == func &&
+ get_fgraph_type(current, index + FGRAPH_RET_INDEX) == FGRAPH_TYPE_BITMAP &&
+ !is_fgraph_index_set(current, index + FGRAPH_RET_INDEX, fgraph_idx))
+ return index + FGRAPH_RET_INDEX;
+
+ val = (FGRAPH_TYPE_RESERVED << FGRAPH_TYPE_SHIFT) | FGRAPH_RET_INDEX;
+
BUILD_BUG_ON(SHADOW_STACK_SIZE % sizeof(long));
/*
@@ -252,17 +275,19 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
smp_rmb();
/* The return trace stack is full */
- if (current->curr_ret_stack >= SHADOW_STACK_MAX_INDEX) {
+ if (current->curr_ret_stack + FGRAPH_RET_INDEX >= SHADOW_STACK_MAX_INDEX) {
atomic_inc(¤t->trace_overrun);
return -EBUSY;
}
calltime = trace_clock_local();
- index = current->curr_ret_stack;
- /* ret offset = 1 ; type = reserved */
- current->ret_stack[index + FGRAPH_RET_INDEX] = 1;
+ index = READ_ONCE(current->curr_ret_stack);
ret_stack = RET_STACK(current, index);
+ index += FGRAPH_RET_INDEX;
+
+ /* ret offset = FGRAPH_RET_INDEX ; type = reserved */
+ current->ret_stack[index] = val;
ret_stack->ret = ret;
/*
* The unwinders expect curr_ret_stack to point to either zero
@@ -278,7 +303,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
* at least a correct index!
*/
barrier();
- current->curr_ret_stack += FGRAPH_RET_INDEX + 1;
+ current->curr_ret_stack = index + 1;
/*
* This next barrier is to ensure that an interrupt coming in
* will not corrupt what we are about to write.
@@ -286,7 +311,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
barrier();
/* Still keep it reserved even if an interrupt came in */
- current->ret_stack[index + FGRAPH_RET_INDEX] = 1;
+ current->ret_stack[index] = val;
ret_stack->ret = ret;
ret_stack->func = func;
@@ -297,7 +322,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
#ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
ret_stack->retp = retp;
#endif
- return 0;
+ return index;
}
/*
@@ -314,15 +339,13 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
# define MCOUNT_INSN_SIZE 0
#endif
+/* If the caller does not use ftrace, call this function. */
int function_graph_enter(unsigned long ret, unsigned long func,
unsigned long frame_pointer, unsigned long *retp)
{
struct ftrace_graph_ent trace;
- int offset;
- int start;
- int type;
- int val;
- int cnt = 0;
+ unsigned long bitmap = 0;
+ int index;
int i;
#ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
@@ -337,69 +360,33 @@ int function_graph_enter(unsigned long ret, unsigned long func,
return -EBUSY;
#endif
- if (!ftrace_ops_test(&global_ops, func, NULL))
- return -EBUSY;
-
trace.func = func;
trace.depth = ++current->curr_ret_depth;
- if (ftrace_push_return_trace(ret, func, frame_pointer, retp))
+ index = ftrace_push_return_trace(ret, func, frame_pointer, retp, 0);
+ if (index < 0)
goto out;
- /* Use start for the distance to ret_stack (skipping over reserve) */
- start = offset = current->curr_ret_stack - 2;
-
for (i = 0; i < fgraph_array_cnt; i++) {
struct fgraph_ops *gops = fgraph_array[i];
if (gops == &fgraph_stub)
continue;
- if ((offset == start) &&
- (current->curr_ret_stack >= SHADOW_STACK_INDEX - 1)) {
- atomic_inc(¤t->trace_overrun);
- break;
- }
- if (fgraph_array[i]->entryfunc(&trace, fgraph_array[i])) {
- offset = current->curr_ret_stack;
- /* Check the top level stored word */
- type = get_fgraph_type(current, offset - 1);
-
- val = (i << FGRAPH_ARRAY_SHIFT) |
- (FGRAPH_TYPE_ARRAY << FGRAPH_TYPE_SHIFT) |
- ((offset - start) - 1);
-
- /* We can reuse the top word if it is reserved */
- if (type == FGRAPH_TYPE_RESERVED) {
- current->ret_stack[offset - 1] = val;
- cnt++;
- continue;
- }
- val++;
-
- current->ret_stack[offset] = val;
- /*
- * Write the value before we increment, so that
- * if an interrupt comes in after we increment
- * it will still see the value and skip over
- * this.
- */
- barrier();
- current->curr_ret_stack++;
- /*
- * Have to write again, in case an interrupt
- * came in before the increment and after we
- * wrote the value.
- */
- barrier();
- current->ret_stack[offset] = val;
- cnt++;
- }
+ if (ftrace_ops_test(&gops->ops, func, NULL) &&
+ gops->entryfunc(&trace, gops))
+ bitmap |= BIT(i);
}
- if (!cnt)
+ if (!bitmap)
goto out_ret;
+ /*
+ * Since this function uses fgraph_idx = 0 as a tail-call checking
+ * flag, set that bit always.
+ */
+ set_fgraph_index_bitmap(current, index, bitmap | BIT(0));
+
return 0;
out_ret:
current->curr_ret_stack -= FGRAPH_RET_INDEX + 1;
@@ -408,15 +395,51 @@ int function_graph_enter(unsigned long ret, unsigned long func,
return -EBUSY;
}
+/* This is called from ftrace_graph_func() via ftrace */
+int function_graph_enter_ops(unsigned long ret, unsigned long func,
+ unsigned long frame_pointer, unsigned long *retp,
+ struct fgraph_ops *gops)
+{
+ struct ftrace_graph_ent trace;
+ int index;
+ int type;
+
+
+ /* Use start for the distance to ret_stack (skipping over reserve) */
+ index = ftrace_push_return_trace(ret, func, frame_pointer, retp, gops->idx);
+ if (index < 0)
+ return index;
+ type = get_fgraph_type(current, index);
+
+ /* This is the first ret_stack for this fentry */
+ if (type == FGRAPH_TYPE_RESERVED)
+ ++current->curr_ret_depth;
+
+ trace.func = func;
+ trace.depth = current->curr_ret_depth;
+ if (gops->entryfunc(&trace, gops)) {
+ if (type == FGRAPH_TYPE_RESERVED)
+ set_fgraph_index_bitmap(current, index, BIT(gops->idx));
+ else
+ add_fgraph_index_bitmap(current, index, BIT(gops->idx));
+ return 0;
+ }
+
+ if (type == FGRAPH_TYPE_RESERVED) {
+ current->curr_ret_stack -= FGRAPH_RET_INDEX + 1;
+ current->curr_ret_depth--;
+ }
+ return -EBUSY;
+}
+
/* Retrieve a function return address to the trace stack on thread info.*/
static struct ftrace_ret_stack *
ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
- unsigned long frame_pointer)
+ unsigned long frame_pointer, int *index)
{
struct ftrace_ret_stack *ret_stack;
- int index;
- ret_stack = get_ret_stack(current, current->curr_ret_stack, &index);
+ ret_stack = get_ret_stack(current, current->curr_ret_stack, index);
if (unlikely(!ret_stack)) {
ftrace_graph_stop();
@@ -455,6 +478,7 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
}
#endif
+ *index += FGRAPH_RET_INDEX;
*ret = ret_stack->ret;
trace->func = ret_stack->func;
trace->calltime = ret_stack->calltime;
@@ -507,13 +531,12 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
{
struct ftrace_ret_stack *ret_stack;
struct ftrace_graph_ret trace;
+ unsigned long bitmap;
unsigned long ret;
- int offset;
int index;
- int idx;
int i;
- ret_stack = ftrace_pop_return_trace(&trace, &ret, frame_pointer);
+ ret_stack = ftrace_pop_return_trace(&trace, &ret, frame_pointer, &index);
if (unlikely(!ret_stack)) {
ftrace_graph_stop();
@@ -527,16 +550,17 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
trace.retval = fgraph_ret_regs_return_value(ret_regs);
#endif
- offset = current->curr_ret_stack - 1;
- index = get_ret_stack_index(current, offset);
+ bitmap = get_fgraph_index_bitmap(current, index);
+ for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) {
+ struct fgraph_ops *gops = fgraph_array[i];
- /* index has to be at least one! Optimize for it */
- i = 0;
- do {
- idx = get_fgraph_array(current, offset - i);
- fgraph_array[idx]->retfunc(&trace, fgraph_array[idx]);
- i++;
- } while (i < index);
+ if (!(bitmap & BIT(i)))
+ continue;
+ if (gops == &fgraph_stub)
+ continue;
+
+ gops->retfunc(&trace, gops);
+ }
/*
* The ftrace_graph_return() may still access the current
@@ -544,7 +568,7 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
* curr_ret_stack is after that.
*/
barrier();
- current->curr_ret_stack -= index + FGRAPH_RET_INDEX;
+ current->curr_ret_stack -= FGRAPH_RET_INDEX + 1;
current->curr_ret_depth--;
return ret;
}
@@ -622,7 +646,17 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
ret_stack = get_ret_stack(current, i, &i);
if (!ret_stack)
break;
- if (ret_stack->retp == retp)
+ /*
+ * For the tail-call, there would be 2 or more ftrace_ret_stacks on
+ * the ret_stack, which records "return_to_handler" as the return
+ * address excpt for the last one.
+ * But on the real stack, there should be 1 entry because tail-call
+ * reuses the return address on the stack and jump to the next function.
+ * Thus we will continue to find real return address.
+ */
+ if (ret_stack->retp == retp &&
+ ret_stack->ret !=
+ (unsigned long)dereference_kernel_function_descriptor(return_to_handler))
return ret_stack->ret;
}
@@ -645,6 +679,9 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
i = *idx;
do {
ret_stack = get_ret_stack(task, task_idx, &task_idx);
+ if (ret_stack && ret_stack->ret ==
+ (unsigned long)dereference_kernel_function_descriptor(return_to_handler))
+ continue;
i--;
} while (i >= 0 && ret_stack);
@@ -655,17 +692,25 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
}
#endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
-static struct ftrace_ops graph_ops = {
- .func = ftrace_graph_func,
- .flags = FTRACE_OPS_FL_INITIALIZED |
- FTRACE_OPS_FL_PID |
- FTRACE_OPS_GRAPH_STUB,
+void fgraph_init_ops(struct ftrace_ops *dst_ops,
+ struct ftrace_ops *src_ops)
+{
+ dst_ops->func = ftrace_graph_func;
+ dst_ops->flags = FTRACE_OPS_FL_PID | FTRACE_OPS_GRAPH_STUB;
+
#ifdef FTRACE_GRAPH_TRAMP_ADDR
- .trampoline = FTRACE_GRAPH_TRAMP_ADDR,
+ dst_ops->trampoline = FTRACE_GRAPH_TRAMP_ADDR;
/* trampoline_size is only needed for dynamically allocated tramps */
#endif
- ASSIGN_OPS_HASH(graph_ops, &global_ops.local_hash)
-};
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+ if (src_ops) {
+ dst_ops->func_hash = &src_ops->local_hash;
+ mutex_init(&dst_ops->local_hash.regex_lock);
+ dst_ops->flags |= FTRACE_OPS_FL_INITIALIZED;
+ }
+#endif
+}
void ftrace_graph_sleep_time_control(bool enable)
{
@@ -869,11 +914,20 @@ static int start_graph_tracing(void)
int register_ftrace_graph(struct fgraph_ops *gops)
{
+ int command = 0;
int ret = 0;
int i;
mutex_lock(&ftrace_lock);
+ if (!gops->ops.func) {
+ gops->ops.flags |= FTRACE_OPS_GRAPH_STUB;
+ gops->ops.func = ftrace_graph_func;
+#ifdef FTRACE_GRAPH_TRAMP_ADDR
+ gops->ops.trampoline = FTRACE_GRAPH_TRAMP_ADDR;
+#endif
+ }
+
if (!fgraph_array[0]) {
/* The array must always have real data on it */
for (i = 0; i < FGRAPH_ARRAY_SIZE; i++)
@@ -893,6 +947,7 @@ int register_ftrace_graph(struct fgraph_ops *gops)
fgraph_array[i] = gops;
if (i + 1 > fgraph_array_cnt)
fgraph_array_cnt = i + 1;
+ gops->idx = i;
ftrace_graph_active++;
@@ -909,9 +964,10 @@ int register_ftrace_graph(struct fgraph_ops *gops)
*/
ftrace_graph_return = return_run;
ftrace_graph_entry = entry_run;
-
- ret = ftrace_startup(&graph_ops, FTRACE_START_FUNC_RET);
+ command = FTRACE_START_FUNC_RET;
}
+
+ ret = ftrace_startup(&gops->ops, command);
out:
mutex_unlock(&ftrace_lock);
return ret;
@@ -919,6 +975,7 @@ int register_ftrace_graph(struct fgraph_ops *gops)
void unregister_ftrace_graph(struct fgraph_ops *gops)
{
+ int command = 0;
int i;
mutex_lock(&ftrace_lock);
@@ -926,25 +983,29 @@ void unregister_ftrace_graph(struct fgraph_ops *gops)
if (unlikely(!ftrace_graph_active))
goto out;
- for (i = 0; i < fgraph_array_cnt; i++)
- if (gops == fgraph_array[i])
- break;
- if (i >= fgraph_array_cnt)
+ if (unlikely(gops->idx < 0 || gops->idx >= fgraph_array_cnt))
goto out;
- fgraph_array[i] = &fgraph_stub;
- if (i + 1 == fgraph_array_cnt) {
- for (; i >= 0; i--)
- if (fgraph_array[i] != &fgraph_stub)
- break;
+ WARN_ON_ONCE(fgraph_array[gops->idx] != gops);
+
+ fgraph_array[gops->idx] = &fgraph_stub;
+ if (gops->idx + 1 == fgraph_array_cnt) {
+ i = gops->idx;
+ while (i >= 0 && fgraph_array[i] == &fgraph_stub)
+ i--;
fgraph_array_cnt = i + 1;
}
ftrace_graph_active--;
+
+ if (!ftrace_graph_active)
+ command = FTRACE_STOP_FUNC_RET;
+
+ ftrace_shutdown(&gops->ops, command);
+
if (!ftrace_graph_active) {
ftrace_graph_return = ftrace_stub_graph;
ftrace_graph_entry = ftrace_graph_entry_stub;
- ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET);
unregister_pm_notifier(&ftrace_suspend_notifier);
unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
}
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 83fbfb7b48f8..c4cc2a9d0047 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3050,6 +3050,8 @@ int ftrace_startup(struct ftrace_ops *ops, int command)
if (unlikely(ftrace_disabled))
return -ENODEV;
+ ftrace_ops_init(ops);
+
ret = __register_ftrace_function(ops);
if (ret)
return ret;
@@ -7319,7 +7321,7 @@ __init void ftrace_init_global_array_ops(struct trace_array *tr)
tr->ops = &global_ops;
tr->ops->private = tr;
ftrace_init_trace_array(tr);
- init_array_fgraph_ops(tr);
+ init_array_fgraph_ops(tr, tr->ops);
}
void ftrace_init_array_ops(struct trace_array *tr, ftrace_func_t func)
@@ -8051,7 +8053,7 @@ static int register_ftrace_function_nolock(struct ftrace_ops *ops)
*/
int register_ftrace_function(struct ftrace_ops *ops)
{
- int ret;
+ int ret = -1;
lock_direct_mutex();
ret = prepare_direct_functions_for_ipmodify(ops);
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 16948c0ed00a..02edfdb68933 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -890,8 +890,8 @@ extern int __trace_graph_entry(struct trace_array *tr,
extern void __trace_graph_return(struct trace_array *tr,
struct ftrace_graph_ret *trace,
unsigned int trace_ctx);
-extern void init_array_fgraph_ops(struct trace_array *tr);
-extern int allocate_fgraph_ops(struct trace_array *tr);
+extern void init_array_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops);
+extern int allocate_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops);
extern void free_fgraph_ops(struct trace_array *tr);
#ifdef CONFIG_DYNAMIC_FTRACE
@@ -974,6 +974,7 @@ static inline int ftrace_graph_notrace_addr(unsigned long addr)
preempt_enable_notrace();
return ret;
}
+
#else
static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
{
@@ -999,18 +1000,19 @@ static inline bool ftrace_graph_ignore_func(struct ftrace_graph_ent *trace)
(fgraph_max_depth && trace->depth >= fgraph_max_depth);
}
+void fgraph_init_ops(struct ftrace_ops *dst_ops,
+ struct ftrace_ops *src_ops);
+
#else /* CONFIG_FUNCTION_GRAPH_TRACER */
static inline enum print_line_t
print_graph_function_flags(struct trace_iterator *iter, u32 flags)
{
return TRACE_TYPE_UNHANDLED;
}
-static inline void init_array_fgraph_ops(struct trace_array *tr) { }
-static inline int allocate_fgraph_ops(struct trace_array *tr)
-{
- return 0;
-}
static inline void free_fgraph_ops(struct trace_array *tr) { }
+/* ftrace_ops may not be defined */
+#define init_array_fgraph_ops(tr, ops) do { } while (0)
+#define allocate_fgraph_ops(tr, ops) ({ 0; })
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
extern struct list_head ftrace_pids;
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 8e8da0d0ee52..13bf2415245d 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -91,7 +91,7 @@ int ftrace_create_function_files(struct trace_array *tr,
if (!tr->ops)
return -EINVAL;
- ret = allocate_fgraph_ops(tr);
+ ret = allocate_fgraph_ops(tr, tr->ops);
if (ret) {
kfree(tr->ops);
return ret;
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 9ccc904a7703..7f30652f0e97 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -288,7 +288,7 @@ static struct fgraph_ops funcgraph_ops = {
.retfunc = &trace_graph_return,
};
-int allocate_fgraph_ops(struct trace_array *tr)
+int allocate_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops)
{
struct fgraph_ops *gops;
@@ -301,6 +301,9 @@ int allocate_fgraph_ops(struct trace_array *tr)
tr->gops = gops;
gops->private = tr;
+
+ fgraph_init_ops(&gops->ops, ops);
+
return 0;
}
@@ -309,10 +312,11 @@ void free_fgraph_ops(struct trace_array *tr)
kfree(tr->gops);
}
-__init void init_array_fgraph_ops(struct trace_array *tr)
+__init void init_array_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops)
{
tr->gops = &funcgraph_ops;
funcgraph_ops.private = tr;
+ fgraph_init_ops(&tr->gops->ops, ops);
}
static int graph_trace_init(struct trace_array *tr)
^ permalink raw reply related [flat|nested] 56+ messages in thread* Re: [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering
2023-12-18 13:13 ` [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering Masami Hiramatsu (Google)
@ 2023-12-26 0:20 ` Masami Hiramatsu
2024-01-05 17:09 ` Mark Rutland
1 sibling, 0 replies; 56+ messages in thread
From: Masami Hiramatsu @ 2023-12-26 0:20 UTC (permalink / raw)
To: Masami Hiramatsu (Google)
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
Hi,
On Mon, 18 Dec 2023 22:13:46 +0900
"Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote:
> @@ -408,15 +395,51 @@ int function_graph_enter(unsigned long ret, unsigned long func,
> return -EBUSY;
> }
>
> +/* This is called from ftrace_graph_func() via ftrace */
> +int function_graph_enter_ops(unsigned long ret, unsigned long func,
> + unsigned long frame_pointer, unsigned long *retp,
> + struct fgraph_ops *gops)
> +{
> + struct ftrace_graph_ent trace;
> + int index;
> + int type;
> +
Here, I found that this needs to check whether the fgraph_array[gops->idx]
is still valid or not. When unregistering the fgraph, fgraph_array[idx] is
cleared (with fgraph_stub) and disable ftrace. So there is a chance to hit
this and it will mess up the shadow stack because gops->idx is already invalid.
Thank you,
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 56+ messages in thread* Re: [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering
2023-12-18 13:13 ` [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering Masami Hiramatsu (Google)
2023-12-26 0:20 ` Masami Hiramatsu
@ 2024-01-05 17:09 ` Mark Rutland
2024-01-08 1:14 ` Masami Hiramatsu
1 sibling, 1 reply; 56+ messages in thread
From: Mark Rutland @ 2024-01-05 17:09 UTC (permalink / raw)
To: Masami Hiramatsu (Google)
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Mon, Dec 18, 2023 at 10:13:46PM +0900, Masami Hiramatsu (Google) wrote:
> From: Steven Rostedt (VMware) <rostedt@goodmis.org>
>
> Allow for instances to have their own ftrace_ops part of the fgraph_ops
> that makes the funtion_graph tracer filter on the set_ftrace_filter file
> of the instance and not the top instance.
>
> This also change how the function_graph handles multiple instances on the
> shadow stack. Previously we use ARRAY type entries to record which one
> is enabled, and this makes it a bitmap of the fgraph_array's indexes.
> Previous function_graph_enter() expects calling back from
> prepare_ftrace_return() function which is called back only once if it is
> enabled. But this introduces different ftrace_ops for each fgraph
> instance and those are called from ftrace_graph_func() one by one. Thus
> we can not loop on the fgraph_array(), and need to reuse the ret_stack
> pushed by the previous instance. Finding the ret_stack is easy because
> we can check the ret_stack->func. But that is not enough for the self-
> recursive tail-call case. Thus fgraph uses the bitmap entry to find it
> is already set (this means that entry is for previous tail call).
>
> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
As a heads-up, while testing the topic/fprobe-on-fgraph branch on arm64, I get
a warning which bisets down to this commit:
| Testing tracer function_graph:
| ------------[ cut here ]------------
| WARNING: CPU: 2 PID: 0 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x3c0/0x3d8
| Modules linked in:
| CPU: 2 PID: 0 Comm: swapper/2 Not tainted 6.7.0-rc2-00026-gea1e68a341c2 #12
| Hardware name: linux,dummy-virt (DT)
| pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
| pc : arch_stack_walk+0x3c0/0x3d8
| lr : arch_stack_walk+0x260/0x3d8
| sp : ffff80008318be00
| x29: ffff80008318be00 x28: ffff000003c0ae80 x27: 0000000000000000
| x26: 0000000000000000 x25: ffff000003c0ae80 x24: 0000000000000000
| x23: ffff8000800234c8 x22: ffff80008002dc30 x21: ffff800080035d10
| x20: ffff80008318bee8 x19: ffff800080023460 x18: ffff800083453c68
| x17: 0000000000000000 x16: ffff800083188000 x15: 000000008ccc5058
| x14: 0000000000000004 x13: ffff800082b8c4f0 x12: 0000000000000000
| x11: ffff800081fba9b0 x10: ffff80008318bff0 x9 : ffff800080010798
| x8 : ffff80008002dc30 x7 : ffff000003c0ae80 x6 : 00000000ffffffff
| x5 : 0000000000000000 x4 : ffff8000832a3c18 x3 : ffff80008318bff0
| x2 : ffff80008002dc30 x1 : ffff80008002dc30 x0 : ffff80008002dc30
| Call trace:
| arch_stack_walk+0x3c0/0x3d8
| return_address+0x40/0x80
| trace_hardirqs_on+0x8c/0x198
| __do_softirq+0xe8/0x440
| ---[ end trace 0000000000000000 ]---
That's a warning in arm64's unwind_recover_return_address() function, which
fires when ftrace_graph_ret_addr() finds return_to_handler:
if (state->task->ret_stack &&
(state->pc == (unsigned long)return_to_handler)) {
unsigned long orig_pc;
orig_pc = ftrace_graph_ret_addr(state->task, NULL, state->pc,
(void *)state->fp);
if (WARN_ON_ONCE(state->pc == orig_pc))
return -EINVAL;
state->pc = orig_pc;
}
The rationale there is that since tail calls are (currently) disabled on arm64,
the only reason for ftrace_graph_ret_addr() to return return_to_handler is when
it fails to find the original return address.
Does this change make it legitimate for ftrace_graph_ret_addr() to return
return_to_handler in other cases, or is that a bug?
Either way, we'll need *some* way to recover the original return addresss...
Mark.
> ---
> Changes in v4:
> - Simplify get_ret_stack() sanity check and use WARN_ON_ONCE() for
> obviously wrong value.
> - Do not check ret == return_to_handler but always read the previous
> ret_stack in ftrace_push_return_trace() to check it is reusable.
> - Set the bit 0 of the bitmap entry always in function_graph_enter()
> because it uses bit 0 to check re-usability.
> - Fix to ensure the ret_stack entry is bitmap type when checking the
> bitmap.
> Changes in v3:
> - Pass current fgraph_ops to the new entry handler
> (function_graph_enter_ops) if fgraph use ftrace.
> - Add fgraph_ops::idx in this patch.
> - Replace the array type with the bitmap type so that it can record
> which fgraph is called.
> - Fix some helper function to use passed task_struct instead of current.
> - Reduce the ret-index size to 1024 words.
> - Make the ret-index directly points the ret_stack.
> - Fix ftrace_graph_ret_addr() to handle tail-call case correctly.
> Changes in v2:
> - Use ftrace_graph_func and FTRACE_OPS_GRAPH_STUB instead of
> ftrace_stub and FTRACE_OPS_FL_STUB for new ftrace based fgraph.
> ---
> arch/arm64/kernel/ftrace.c | 19 ++
> arch/x86/kernel/ftrace.c | 19 ++
> include/linux/ftrace.h | 7 +
> kernel/trace/fgraph.c | 369 ++++++++++++++++++++--------------
> kernel/trace/ftrace.c | 6 -
> kernel/trace/trace.h | 16 +
> kernel/trace/trace_functions.c | 2
> kernel/trace/trace_functions_graph.c | 8 +
> 8 files changed, 277 insertions(+), 169 deletions(-)
>
> diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
> index a650f5e11fc5..205937e04ece 100644
> --- a/arch/arm64/kernel/ftrace.c
> +++ b/arch/arm64/kernel/ftrace.c
> @@ -481,7 +481,24 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
> void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
> struct ftrace_ops *op, struct ftrace_regs *fregs)
> {
> - prepare_ftrace_return(ip, &fregs->lr, fregs->fp);
> + unsigned long *parent = &fregs->lr;
> + struct fgraph_ops *gops = container_of(op, struct fgraph_ops, ops);
> + int bit;
> +
> + if (unlikely(ftrace_graph_is_dead()))
> + return;
> +
> + if (unlikely(atomic_read(¤t->tracing_graph_pause)))
> + return;
> +
> + bit = ftrace_test_recursion_trylock(ip, *parent);
> + if (bit < 0)
> + return;
> +
> + if (!function_graph_enter_ops(*parent, ip, fregs->fp, parent, gops))
> + *parent = (unsigned long)&return_to_handler;
> +
> + ftrace_test_recursion_unlock(bit);
> }
> #else
> /*
> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> index 12df54ff0e81..845e29b4254f 100644
> --- a/arch/x86/kernel/ftrace.c
> +++ b/arch/x86/kernel/ftrace.c
> @@ -657,9 +657,24 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
> struct ftrace_ops *op, struct ftrace_regs *fregs)
> {
> struct pt_regs *regs = &fregs->regs;
> - unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs);
> + unsigned long *parent = (unsigned long *)kernel_stack_pointer(regs);
> + struct fgraph_ops *gops = container_of(op, struct fgraph_ops, ops);
> + int bit;
> +
> + if (unlikely(ftrace_graph_is_dead()))
> + return;
> +
> + if (unlikely(atomic_read(¤t->tracing_graph_pause)))
> + return;
>
> - prepare_ftrace_return(ip, (unsigned long *)stack, 0);
> + bit = ftrace_test_recursion_trylock(ip, *parent);
> + if (bit < 0)
> + return;
> +
> + if (!function_graph_enter_ops(*parent, ip, 0, parent, gops))
> + *parent = (unsigned long)&return_to_handler;
> +
> + ftrace_test_recursion_unlock(bit);
> }
> #endif
>
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index 7b08169aa51d..c431a33fe789 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -1070,7 +1070,9 @@ extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph
> struct fgraph_ops {
> trace_func_graph_ent_t entryfunc;
> trace_func_graph_ret_t retfunc;
> + struct ftrace_ops ops; /* for the hash lists */
> void *private;
> + int idx;
> };
>
> /*
> @@ -1104,6 +1106,11 @@ extern int
> function_graph_enter(unsigned long ret, unsigned long func,
> unsigned long frame_pointer, unsigned long *retp);
>
> +extern int
> +function_graph_enter_ops(unsigned long ret, unsigned long func,
> + unsigned long frame_pointer, unsigned long *retp,
> + struct fgraph_ops *gops);
> +
> struct ftrace_ret_stack *
> ftrace_graph_get_ret_stack(struct task_struct *task, int idx);
>
> diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> index 62c35d6d95f9..6f537ebd3ed7 100644
> --- a/kernel/trace/fgraph.c
> +++ b/kernel/trace/fgraph.c
> @@ -7,6 +7,7 @@
> *
> * Highly modified by Steven Rostedt (VMware).
> */
> +#include <linux/bits.h>
> #include <linux/jump_label.h>
> #include <linux/suspend.h>
> #include <linux/ftrace.h>
> @@ -17,22 +18,15 @@
> #include "ftrace_internal.h"
> #include "trace.h"
>
> -#ifdef CONFIG_DYNAMIC_FTRACE
> -#define ASSIGN_OPS_HASH(opsname, val) \
> - .func_hash = val, \
> - .local_hash.regex_lock = __MUTEX_INITIALIZER(opsname.local_hash.regex_lock),
> -#else
> -#define ASSIGN_OPS_HASH(opsname, val)
> -#endif
> -
> #define FGRAPH_RET_SIZE sizeof(struct ftrace_ret_stack)
> #define FGRAPH_RET_INDEX (FGRAPH_RET_SIZE / sizeof(long))
>
> /*
> * On entry to a function (via function_graph_enter()), a new ftrace_ret_stack
> - * is allocated on the task's ret_stack, then each fgraph_ops on the
> - * fgraph_array[]'s entryfunc is called and if that returns non-zero, the
> - * index into the fgraph_array[] for that fgraph_ops is added to the ret_stack.
> + * is allocated on the task's ret_stack with indexes entry, then each
> + * fgraph_ops on the fgraph_array[]'s entryfunc is called and if that returns
> + * non-zero, the index into the fgraph_array[] for that fgraph_ops is recorded
> + * on the indexes entry as a bit flag.
> * As the associated ftrace_ret_stack saved for those fgraph_ops needs to
> * be found, the index to it is also added to the ret_stack along with the
> * index of the fgraph_array[] to each fgraph_ops that needs their retfunc
> @@ -42,61 +36,59 @@
> * to the last ftrace_ret_stack saved. All references to the
> * ftrace_ret_stack has the format of:
> *
> - * bits: 0 - 13 Index in words from the previous ftrace_ret_stack
> - * bits: 14 - 15 Type of storage
> + * bits: 0 - 9 offset in words from the previous ftrace_ret_stack
> + * (bitmap type should have FGRAPH_RET_INDEX always)
> + * bits: 10 - 11 Type of storage
> * 0 - reserved
> - * 1 - fgraph_array index
> - * For fgraph_array_index:
> - * bits: 16 - 23 The fgraph_ops fgraph_array index
> + * 1 - bitmap of fgraph_array index
> + *
> + * For bitmap of fgraph_array index
> + * bits: 12 - 27 The bitmap of fgraph_ops fgraph_array index
> *
> * That is, at the end of function_graph_enter, if the first and forth
> * fgraph_ops on the fgraph_array[] (index 0 and 3) needs their retfunc called
> * on the return of the function being traced, this is what will be on the
> * task's shadow ret_stack: (the stack grows upward)
> *
> - * | | <- task->curr_ret_stack
> - * +----------------------------------+
> - * | (3 << FGRAPH_ARRAY_SHIFT)|(2) | ( 3 for index of fourth fgraph_ops)
> - * +----------------------------------+
> - * | (0 << FGRAPH_ARRAY_SHIFT)|(1) | ( 0 for index of first fgraph_ops)
> - * +----------------------------------+
> - * | struct ftrace_ret_stack |
> - * | (stores the saved ret pointer) |
> - * +----------------------------------+
> - * | (X) | (N) | ( N words away from previous ret_stack)
> - * | |
> + * | | <- task->curr_ret_stack
> + * +--------------------------------------------+
> + * | bitmap_type(bitmap:(BIT(3)|BIT(0)), |
> + * | offset:FGRAPH_RET_INDEX) | <- the offset is from here
> + * +--------------------------------------------+
> + * | struct ftrace_ret_stack |
> + * | (stores the saved ret pointer) | <- the offset points here
> + * +--------------------------------------------+
> + * | (X) | (N) | ( N words away from
> + * | | previous ret_stack)
> *
> * If a backtrace is required, and the real return pointer needs to be
> * fetched, then it looks at the task's curr_ret_stack index, if it
> - * is greater than zero, it would subtact one, and then mask the value
> - * on the ret_stack by FGRAPH_RET_INDEX_MASK and subtract FGRAPH_RET_INDEX
> - * from that, to get the index of the ftrace_ret_stack structure stored
> - * on the shadow stack.
> + * is greater than zero (reserved, or right before poped), it would mask
> + * the value by FGRAPH_RET_INDEX_MASK to get the offset index of the
> + * ftrace_ret_stack structure stored on the shadow stack.
> */
>
> -#define FGRAPH_RET_INDEX_SIZE 14
> -#define FGRAPH_RET_INDEX_MASK ((1 << FGRAPH_RET_INDEX_SIZE) - 1)
> -
> +#define FGRAPH_RET_INDEX_SIZE 10
> +#define FGRAPH_RET_INDEX_MASK GENMASK(FGRAPH_RET_INDEX_SIZE - 1, 0)
>
> #define FGRAPH_TYPE_SIZE 2
> -#define FGRAPH_TYPE_MASK ((1 << FGRAPH_TYPE_SIZE) - 1)
> +#define FGRAPH_TYPE_MASK GENMASK(FGRAPH_TYPE_SIZE - 1, 0)
> #define FGRAPH_TYPE_SHIFT FGRAPH_RET_INDEX_SIZE
>
> enum {
> FGRAPH_TYPE_RESERVED = 0,
> - FGRAPH_TYPE_ARRAY = 1,
> + FGRAPH_TYPE_BITMAP = 1,
> };
>
> -#define FGRAPH_ARRAY_SIZE 16
> -#define FGRAPH_ARRAY_MASK ((1 << FGRAPH_ARRAY_SIZE) - 1)
> -#define FGRAPH_ARRAY_SHIFT (FGRAPH_TYPE_SHIFT + FGRAPH_TYPE_SIZE)
> +#define FGRAPH_INDEX_SIZE 16
> +#define FGRAPH_INDEX_MASK GENMASK(FGRAPH_INDEX_SIZE - 1, 0)
> +#define FGRAPH_INDEX_SHIFT (FGRAPH_TYPE_SHIFT + FGRAPH_TYPE_SIZE)
>
> /* Currently the max stack index can't be more than register callers */
> -#define FGRAPH_MAX_INDEX FGRAPH_ARRAY_SIZE
> +#define FGRAPH_MAX_INDEX (FGRAPH_INDEX_SIZE + FGRAPH_RET_INDEX)
> +
> +#define FGRAPH_ARRAY_SIZE FGRAPH_INDEX_SIZE
>
> -#define FGRAPH_FRAME_SIZE (FGRAPH_RET_SIZE + FGRAPH_ARRAY_SIZE * (sizeof(long)))
> -#define FGRAPH_FRAME_INDEX (ALIGN(FGRAPH_FRAME_SIZE, \
> - sizeof(long)) / sizeof(long))
> #define SHADOW_STACK_SIZE (PAGE_SIZE)
> #define SHADOW_STACK_INDEX (SHADOW_STACK_SIZE / sizeof(long))
> /* Leave on a buffer at the end */
> @@ -113,19 +105,36 @@ static struct fgraph_ops *fgraph_array[FGRAPH_ARRAY_SIZE];
>
> static inline int get_ret_stack_index(struct task_struct *t, int offset)
> {
> - return current->ret_stack[offset] & FGRAPH_RET_INDEX_MASK;
> + return t->ret_stack[offset] & FGRAPH_RET_INDEX_MASK;
> }
>
> static inline int get_fgraph_type(struct task_struct *t, int offset)
> {
> - return (current->ret_stack[offset] >> FGRAPH_TYPE_SHIFT) &
> - FGRAPH_TYPE_MASK;
> + return (t->ret_stack[offset] >> FGRAPH_TYPE_SHIFT) & FGRAPH_TYPE_MASK;
> +}
> +
> +static inline unsigned long
> +get_fgraph_index_bitmap(struct task_struct *t, int offset)
> +{
> + return (t->ret_stack[offset] >> FGRAPH_INDEX_SHIFT) & FGRAPH_INDEX_MASK;
> }
>
> -static inline int get_fgraph_array(struct task_struct *t, int offset)
> +static inline void
> +set_fgraph_index_bitmap(struct task_struct *t, int offset, unsigned long bitmap)
> {
> - return (current->ret_stack[offset] >> FGRAPH_ARRAY_SHIFT) &
> - FGRAPH_ARRAY_MASK;
> + t->ret_stack[offset] = (bitmap << FGRAPH_INDEX_SHIFT) |
> + (FGRAPH_TYPE_BITMAP << FGRAPH_TYPE_SHIFT) | FGRAPH_RET_INDEX;
> +}
> +
> +static inline bool is_fgraph_index_set(struct task_struct *t, int offset, int idx)
> +{
> + return !!(get_fgraph_index_bitmap(t, offset) & BIT(idx));
> +}
> +
> +static inline void
> +add_fgraph_index_bitmap(struct task_struct *t, int offset, unsigned long bitmap)
> +{
> + t->ret_stack[offset] |= (bitmap << FGRAPH_INDEX_SHIFT);
> }
>
> /* ftrace_graph_entry set to this to tell some archs to run function graph */
> @@ -160,17 +169,14 @@ get_ret_stack(struct task_struct *t, int offset, int *index)
>
> BUILD_BUG_ON(FGRAPH_RET_SIZE % sizeof(long));
>
> - if (offset <= 0)
> + if (unlikely(offset <= 0))
> return NULL;
>
> - idx = get_ret_stack_index(t, offset - 1);
> -
> - if (idx <= 0 || idx > FGRAPH_MAX_INDEX)
> + idx = get_ret_stack_index(t, --offset);
> + if (WARN_ON_ONCE(idx <= 0 || idx > offset))
> return NULL;
>
> - offset -= idx + FGRAPH_RET_INDEX;
> - if (offset < 0)
> - return NULL;
> + offset -= idx;
>
> *index = offset;
> return RET_STACK(t, offset);
> @@ -231,10 +237,12 @@ void ftrace_graph_stop(void)
> /* Add a function return address to the trace stack on thread info.*/
> static int
> ftrace_push_return_trace(unsigned long ret, unsigned long func,
> - unsigned long frame_pointer, unsigned long *retp)
> + unsigned long frame_pointer, unsigned long *retp,
> + int fgraph_idx)
> {
> struct ftrace_ret_stack *ret_stack;
> unsigned long long calltime;
> + unsigned long val;
> int index;
>
> if (unlikely(ftrace_graph_is_dead()))
> @@ -243,6 +251,21 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> if (!current->ret_stack)
> return -EBUSY;
>
> + /*
> + * At first, check whether the previous fgraph callback is pushed by
> + * the fgraph on the same function entry.
> + * But if @func is the self tail-call function, we also need to ensure
> + * the ret_stack is not for the previous call by checking whether the
> + * bit of @fgraph_idx is set or not.
> + */
> + ret_stack = get_ret_stack(current, current->curr_ret_stack, &index);
> + if (ret_stack && ret_stack->func == func &&
> + get_fgraph_type(current, index + FGRAPH_RET_INDEX) == FGRAPH_TYPE_BITMAP &&
> + !is_fgraph_index_set(current, index + FGRAPH_RET_INDEX, fgraph_idx))
> + return index + FGRAPH_RET_INDEX;
> +
> + val = (FGRAPH_TYPE_RESERVED << FGRAPH_TYPE_SHIFT) | FGRAPH_RET_INDEX;
> +
> BUILD_BUG_ON(SHADOW_STACK_SIZE % sizeof(long));
>
> /*
> @@ -252,17 +275,19 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> smp_rmb();
>
> /* The return trace stack is full */
> - if (current->curr_ret_stack >= SHADOW_STACK_MAX_INDEX) {
> + if (current->curr_ret_stack + FGRAPH_RET_INDEX >= SHADOW_STACK_MAX_INDEX) {
> atomic_inc(¤t->trace_overrun);
> return -EBUSY;
> }
>
> calltime = trace_clock_local();
>
> - index = current->curr_ret_stack;
> - /* ret offset = 1 ; type = reserved */
> - current->ret_stack[index + FGRAPH_RET_INDEX] = 1;
> + index = READ_ONCE(current->curr_ret_stack);
> ret_stack = RET_STACK(current, index);
> + index += FGRAPH_RET_INDEX;
> +
> + /* ret offset = FGRAPH_RET_INDEX ; type = reserved */
> + current->ret_stack[index] = val;
> ret_stack->ret = ret;
> /*
> * The unwinders expect curr_ret_stack to point to either zero
> @@ -278,7 +303,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> * at least a correct index!
> */
> barrier();
> - current->curr_ret_stack += FGRAPH_RET_INDEX + 1;
> + current->curr_ret_stack = index + 1;
> /*
> * This next barrier is to ensure that an interrupt coming in
> * will not corrupt what we are about to write.
> @@ -286,7 +311,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> barrier();
>
> /* Still keep it reserved even if an interrupt came in */
> - current->ret_stack[index + FGRAPH_RET_INDEX] = 1;
> + current->ret_stack[index] = val;
>
> ret_stack->ret = ret;
> ret_stack->func = func;
> @@ -297,7 +322,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
> ret_stack->retp = retp;
> #endif
> - return 0;
> + return index;
> }
>
> /*
> @@ -314,15 +339,13 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> # define MCOUNT_INSN_SIZE 0
> #endif
>
> +/* If the caller does not use ftrace, call this function. */
> int function_graph_enter(unsigned long ret, unsigned long func,
> unsigned long frame_pointer, unsigned long *retp)
> {
> struct ftrace_graph_ent trace;
> - int offset;
> - int start;
> - int type;
> - int val;
> - int cnt = 0;
> + unsigned long bitmap = 0;
> + int index;
> int i;
>
> #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
> @@ -337,69 +360,33 @@ int function_graph_enter(unsigned long ret, unsigned long func,
> return -EBUSY;
> #endif
>
> - if (!ftrace_ops_test(&global_ops, func, NULL))
> - return -EBUSY;
> -
> trace.func = func;
> trace.depth = ++current->curr_ret_depth;
>
> - if (ftrace_push_return_trace(ret, func, frame_pointer, retp))
> + index = ftrace_push_return_trace(ret, func, frame_pointer, retp, 0);
> + if (index < 0)
> goto out;
>
> - /* Use start for the distance to ret_stack (skipping over reserve) */
> - start = offset = current->curr_ret_stack - 2;
> -
> for (i = 0; i < fgraph_array_cnt; i++) {
> struct fgraph_ops *gops = fgraph_array[i];
>
> if (gops == &fgraph_stub)
> continue;
>
> - if ((offset == start) &&
> - (current->curr_ret_stack >= SHADOW_STACK_INDEX - 1)) {
> - atomic_inc(¤t->trace_overrun);
> - break;
> - }
> - if (fgraph_array[i]->entryfunc(&trace, fgraph_array[i])) {
> - offset = current->curr_ret_stack;
> - /* Check the top level stored word */
> - type = get_fgraph_type(current, offset - 1);
> -
> - val = (i << FGRAPH_ARRAY_SHIFT) |
> - (FGRAPH_TYPE_ARRAY << FGRAPH_TYPE_SHIFT) |
> - ((offset - start) - 1);
> -
> - /* We can reuse the top word if it is reserved */
> - if (type == FGRAPH_TYPE_RESERVED) {
> - current->ret_stack[offset - 1] = val;
> - cnt++;
> - continue;
> - }
> - val++;
> -
> - current->ret_stack[offset] = val;
> - /*
> - * Write the value before we increment, so that
> - * if an interrupt comes in after we increment
> - * it will still see the value and skip over
> - * this.
> - */
> - barrier();
> - current->curr_ret_stack++;
> - /*
> - * Have to write again, in case an interrupt
> - * came in before the increment and after we
> - * wrote the value.
> - */
> - barrier();
> - current->ret_stack[offset] = val;
> - cnt++;
> - }
> + if (ftrace_ops_test(&gops->ops, func, NULL) &&
> + gops->entryfunc(&trace, gops))
> + bitmap |= BIT(i);
> }
>
> - if (!cnt)
> + if (!bitmap)
> goto out_ret;
>
> + /*
> + * Since this function uses fgraph_idx = 0 as a tail-call checking
> + * flag, set that bit always.
> + */
> + set_fgraph_index_bitmap(current, index, bitmap | BIT(0));
> +
> return 0;
> out_ret:
> current->curr_ret_stack -= FGRAPH_RET_INDEX + 1;
> @@ -408,15 +395,51 @@ int function_graph_enter(unsigned long ret, unsigned long func,
> return -EBUSY;
> }
>
> +/* This is called from ftrace_graph_func() via ftrace */
> +int function_graph_enter_ops(unsigned long ret, unsigned long func,
> + unsigned long frame_pointer, unsigned long *retp,
> + struct fgraph_ops *gops)
> +{
> + struct ftrace_graph_ent trace;
> + int index;
> + int type;
> +
> +
> + /* Use start for the distance to ret_stack (skipping over reserve) */
> + index = ftrace_push_return_trace(ret, func, frame_pointer, retp, gops->idx);
> + if (index < 0)
> + return index;
> + type = get_fgraph_type(current, index);
> +
> + /* This is the first ret_stack for this fentry */
> + if (type == FGRAPH_TYPE_RESERVED)
> + ++current->curr_ret_depth;
> +
> + trace.func = func;
> + trace.depth = current->curr_ret_depth;
> + if (gops->entryfunc(&trace, gops)) {
> + if (type == FGRAPH_TYPE_RESERVED)
> + set_fgraph_index_bitmap(current, index, BIT(gops->idx));
> + else
> + add_fgraph_index_bitmap(current, index, BIT(gops->idx));
> + return 0;
> + }
> +
> + if (type == FGRAPH_TYPE_RESERVED) {
> + current->curr_ret_stack -= FGRAPH_RET_INDEX + 1;
> + current->curr_ret_depth--;
> + }
> + return -EBUSY;
> +}
> +
> /* Retrieve a function return address to the trace stack on thread info.*/
> static struct ftrace_ret_stack *
> ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
> - unsigned long frame_pointer)
> + unsigned long frame_pointer, int *index)
> {
> struct ftrace_ret_stack *ret_stack;
> - int index;
>
> - ret_stack = get_ret_stack(current, current->curr_ret_stack, &index);
> + ret_stack = get_ret_stack(current, current->curr_ret_stack, index);
>
> if (unlikely(!ret_stack)) {
> ftrace_graph_stop();
> @@ -455,6 +478,7 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
> }
> #endif
>
> + *index += FGRAPH_RET_INDEX;
> *ret = ret_stack->ret;
> trace->func = ret_stack->func;
> trace->calltime = ret_stack->calltime;
> @@ -507,13 +531,12 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
> {
> struct ftrace_ret_stack *ret_stack;
> struct ftrace_graph_ret trace;
> + unsigned long bitmap;
> unsigned long ret;
> - int offset;
> int index;
> - int idx;
> int i;
>
> - ret_stack = ftrace_pop_return_trace(&trace, &ret, frame_pointer);
> + ret_stack = ftrace_pop_return_trace(&trace, &ret, frame_pointer, &index);
>
> if (unlikely(!ret_stack)) {
> ftrace_graph_stop();
> @@ -527,16 +550,17 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
> trace.retval = fgraph_ret_regs_return_value(ret_regs);
> #endif
>
> - offset = current->curr_ret_stack - 1;
> - index = get_ret_stack_index(current, offset);
> + bitmap = get_fgraph_index_bitmap(current, index);
> + for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) {
> + struct fgraph_ops *gops = fgraph_array[i];
>
> - /* index has to be at least one! Optimize for it */
> - i = 0;
> - do {
> - idx = get_fgraph_array(current, offset - i);
> - fgraph_array[idx]->retfunc(&trace, fgraph_array[idx]);
> - i++;
> - } while (i < index);
> + if (!(bitmap & BIT(i)))
> + continue;
> + if (gops == &fgraph_stub)
> + continue;
> +
> + gops->retfunc(&trace, gops);
> + }
>
> /*
> * The ftrace_graph_return() may still access the current
> @@ -544,7 +568,7 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
> * curr_ret_stack is after that.
> */
> barrier();
> - current->curr_ret_stack -= index + FGRAPH_RET_INDEX;
> + current->curr_ret_stack -= FGRAPH_RET_INDEX + 1;
> current->curr_ret_depth--;
> return ret;
> }
> @@ -622,7 +646,17 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
> ret_stack = get_ret_stack(current, i, &i);
> if (!ret_stack)
> break;
> - if (ret_stack->retp == retp)
> + /*
> + * For the tail-call, there would be 2 or more ftrace_ret_stacks on
> + * the ret_stack, which records "return_to_handler" as the return
> + * address excpt for the last one.
> + * But on the real stack, there should be 1 entry because tail-call
> + * reuses the return address on the stack and jump to the next function.
> + * Thus we will continue to find real return address.
> + */
> + if (ret_stack->retp == retp &&
> + ret_stack->ret !=
> + (unsigned long)dereference_kernel_function_descriptor(return_to_handler))
> return ret_stack->ret;
> }
>
> @@ -645,6 +679,9 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
> i = *idx;
> do {
> ret_stack = get_ret_stack(task, task_idx, &task_idx);
> + if (ret_stack && ret_stack->ret ==
> + (unsigned long)dereference_kernel_function_descriptor(return_to_handler))
> + continue;
> i--;
> } while (i >= 0 && ret_stack);
>
> @@ -655,17 +692,25 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
> }
> #endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
>
> -static struct ftrace_ops graph_ops = {
> - .func = ftrace_graph_func,
> - .flags = FTRACE_OPS_FL_INITIALIZED |
> - FTRACE_OPS_FL_PID |
> - FTRACE_OPS_GRAPH_STUB,
> +void fgraph_init_ops(struct ftrace_ops *dst_ops,
> + struct ftrace_ops *src_ops)
> +{
> + dst_ops->func = ftrace_graph_func;
> + dst_ops->flags = FTRACE_OPS_FL_PID | FTRACE_OPS_GRAPH_STUB;
> +
> #ifdef FTRACE_GRAPH_TRAMP_ADDR
> - .trampoline = FTRACE_GRAPH_TRAMP_ADDR,
> + dst_ops->trampoline = FTRACE_GRAPH_TRAMP_ADDR;
> /* trampoline_size is only needed for dynamically allocated tramps */
> #endif
> - ASSIGN_OPS_HASH(graph_ops, &global_ops.local_hash)
> -};
> +
> +#ifdef CONFIG_DYNAMIC_FTRACE
> + if (src_ops) {
> + dst_ops->func_hash = &src_ops->local_hash;
> + mutex_init(&dst_ops->local_hash.regex_lock);
> + dst_ops->flags |= FTRACE_OPS_FL_INITIALIZED;
> + }
> +#endif
> +}
>
> void ftrace_graph_sleep_time_control(bool enable)
> {
> @@ -869,11 +914,20 @@ static int start_graph_tracing(void)
>
> int register_ftrace_graph(struct fgraph_ops *gops)
> {
> + int command = 0;
> int ret = 0;
> int i;
>
> mutex_lock(&ftrace_lock);
>
> + if (!gops->ops.func) {
> + gops->ops.flags |= FTRACE_OPS_GRAPH_STUB;
> + gops->ops.func = ftrace_graph_func;
> +#ifdef FTRACE_GRAPH_TRAMP_ADDR
> + gops->ops.trampoline = FTRACE_GRAPH_TRAMP_ADDR;
> +#endif
> + }
> +
> if (!fgraph_array[0]) {
> /* The array must always have real data on it */
> for (i = 0; i < FGRAPH_ARRAY_SIZE; i++)
> @@ -893,6 +947,7 @@ int register_ftrace_graph(struct fgraph_ops *gops)
> fgraph_array[i] = gops;
> if (i + 1 > fgraph_array_cnt)
> fgraph_array_cnt = i + 1;
> + gops->idx = i;
>
> ftrace_graph_active++;
>
> @@ -909,9 +964,10 @@ int register_ftrace_graph(struct fgraph_ops *gops)
> */
> ftrace_graph_return = return_run;
> ftrace_graph_entry = entry_run;
> -
> - ret = ftrace_startup(&graph_ops, FTRACE_START_FUNC_RET);
> + command = FTRACE_START_FUNC_RET;
> }
> +
> + ret = ftrace_startup(&gops->ops, command);
> out:
> mutex_unlock(&ftrace_lock);
> return ret;
> @@ -919,6 +975,7 @@ int register_ftrace_graph(struct fgraph_ops *gops)
>
> void unregister_ftrace_graph(struct fgraph_ops *gops)
> {
> + int command = 0;
> int i;
>
> mutex_lock(&ftrace_lock);
> @@ -926,25 +983,29 @@ void unregister_ftrace_graph(struct fgraph_ops *gops)
> if (unlikely(!ftrace_graph_active))
> goto out;
>
> - for (i = 0; i < fgraph_array_cnt; i++)
> - if (gops == fgraph_array[i])
> - break;
> - if (i >= fgraph_array_cnt)
> + if (unlikely(gops->idx < 0 || gops->idx >= fgraph_array_cnt))
> goto out;
>
> - fgraph_array[i] = &fgraph_stub;
> - if (i + 1 == fgraph_array_cnt) {
> - for (; i >= 0; i--)
> - if (fgraph_array[i] != &fgraph_stub)
> - break;
> + WARN_ON_ONCE(fgraph_array[gops->idx] != gops);
> +
> + fgraph_array[gops->idx] = &fgraph_stub;
> + if (gops->idx + 1 == fgraph_array_cnt) {
> + i = gops->idx;
> + while (i >= 0 && fgraph_array[i] == &fgraph_stub)
> + i--;
> fgraph_array_cnt = i + 1;
> }
>
> ftrace_graph_active--;
> +
> + if (!ftrace_graph_active)
> + command = FTRACE_STOP_FUNC_RET;
> +
> + ftrace_shutdown(&gops->ops, command);
> +
> if (!ftrace_graph_active) {
> ftrace_graph_return = ftrace_stub_graph;
> ftrace_graph_entry = ftrace_graph_entry_stub;
> - ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET);
> unregister_pm_notifier(&ftrace_suspend_notifier);
> unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
> }
> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> index 83fbfb7b48f8..c4cc2a9d0047 100644
> --- a/kernel/trace/ftrace.c
> +++ b/kernel/trace/ftrace.c
> @@ -3050,6 +3050,8 @@ int ftrace_startup(struct ftrace_ops *ops, int command)
> if (unlikely(ftrace_disabled))
> return -ENODEV;
>
> + ftrace_ops_init(ops);
> +
> ret = __register_ftrace_function(ops);
> if (ret)
> return ret;
> @@ -7319,7 +7321,7 @@ __init void ftrace_init_global_array_ops(struct trace_array *tr)
> tr->ops = &global_ops;
> tr->ops->private = tr;
> ftrace_init_trace_array(tr);
> - init_array_fgraph_ops(tr);
> + init_array_fgraph_ops(tr, tr->ops);
> }
>
> void ftrace_init_array_ops(struct trace_array *tr, ftrace_func_t func)
> @@ -8051,7 +8053,7 @@ static int register_ftrace_function_nolock(struct ftrace_ops *ops)
> */
> int register_ftrace_function(struct ftrace_ops *ops)
> {
> - int ret;
> + int ret = -1;
>
> lock_direct_mutex();
> ret = prepare_direct_functions_for_ipmodify(ops);
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index 16948c0ed00a..02edfdb68933 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -890,8 +890,8 @@ extern int __trace_graph_entry(struct trace_array *tr,
> extern void __trace_graph_return(struct trace_array *tr,
> struct ftrace_graph_ret *trace,
> unsigned int trace_ctx);
> -extern void init_array_fgraph_ops(struct trace_array *tr);
> -extern int allocate_fgraph_ops(struct trace_array *tr);
> +extern void init_array_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops);
> +extern int allocate_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops);
> extern void free_fgraph_ops(struct trace_array *tr);
>
> #ifdef CONFIG_DYNAMIC_FTRACE
> @@ -974,6 +974,7 @@ static inline int ftrace_graph_notrace_addr(unsigned long addr)
> preempt_enable_notrace();
> return ret;
> }
> +
> #else
> static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
> {
> @@ -999,18 +1000,19 @@ static inline bool ftrace_graph_ignore_func(struct ftrace_graph_ent *trace)
> (fgraph_max_depth && trace->depth >= fgraph_max_depth);
> }
>
> +void fgraph_init_ops(struct ftrace_ops *dst_ops,
> + struct ftrace_ops *src_ops);
> +
> #else /* CONFIG_FUNCTION_GRAPH_TRACER */
> static inline enum print_line_t
> print_graph_function_flags(struct trace_iterator *iter, u32 flags)
> {
> return TRACE_TYPE_UNHANDLED;
> }
> -static inline void init_array_fgraph_ops(struct trace_array *tr) { }
> -static inline int allocate_fgraph_ops(struct trace_array *tr)
> -{
> - return 0;
> -}
> static inline void free_fgraph_ops(struct trace_array *tr) { }
> +/* ftrace_ops may not be defined */
> +#define init_array_fgraph_ops(tr, ops) do { } while (0)
> +#define allocate_fgraph_ops(tr, ops) ({ 0; })
> #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
>
> extern struct list_head ftrace_pids;
> diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
> index 8e8da0d0ee52..13bf2415245d 100644
> --- a/kernel/trace/trace_functions.c
> +++ b/kernel/trace/trace_functions.c
> @@ -91,7 +91,7 @@ int ftrace_create_function_files(struct trace_array *tr,
> if (!tr->ops)
> return -EINVAL;
>
> - ret = allocate_fgraph_ops(tr);
> + ret = allocate_fgraph_ops(tr, tr->ops);
> if (ret) {
> kfree(tr->ops);
> return ret;
> diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
> index 9ccc904a7703..7f30652f0e97 100644
> --- a/kernel/trace/trace_functions_graph.c
> +++ b/kernel/trace/trace_functions_graph.c
> @@ -288,7 +288,7 @@ static struct fgraph_ops funcgraph_ops = {
> .retfunc = &trace_graph_return,
> };
>
> -int allocate_fgraph_ops(struct trace_array *tr)
> +int allocate_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops)
> {
> struct fgraph_ops *gops;
>
> @@ -301,6 +301,9 @@ int allocate_fgraph_ops(struct trace_array *tr)
>
> tr->gops = gops;
> gops->private = tr;
> +
> + fgraph_init_ops(&gops->ops, ops);
> +
> return 0;
> }
>
> @@ -309,10 +312,11 @@ void free_fgraph_ops(struct trace_array *tr)
> kfree(tr->gops);
> }
>
> -__init void init_array_fgraph_ops(struct trace_array *tr)
> +__init void init_array_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops)
> {
> tr->gops = &funcgraph_ops;
> funcgraph_ops.private = tr;
> + fgraph_init_ops(&tr->gops->ops, ops);
> }
>
> static int graph_trace_init(struct trace_array *tr)
>
^ permalink raw reply [flat|nested] 56+ messages in thread* Re: [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering
2024-01-05 17:09 ` Mark Rutland
@ 2024-01-08 1:14 ` Masami Hiramatsu
2024-01-08 12:25 ` Mark Rutland
0 siblings, 1 reply; 56+ messages in thread
From: Masami Hiramatsu @ 2024-01-08 1:14 UTC (permalink / raw)
To: Mark Rutland
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Fri, 5 Jan 2024 17:09:10 +0000
Mark Rutland <mark.rutland@arm.com> wrote:
> On Mon, Dec 18, 2023 at 10:13:46PM +0900, Masami Hiramatsu (Google) wrote:
> > From: Steven Rostedt (VMware) <rostedt@goodmis.org>
> >
> > Allow for instances to have their own ftrace_ops part of the fgraph_ops
> > that makes the funtion_graph tracer filter on the set_ftrace_filter file
> > of the instance and not the top instance.
> >
> > This also change how the function_graph handles multiple instances on the
> > shadow stack. Previously we use ARRAY type entries to record which one
> > is enabled, and this makes it a bitmap of the fgraph_array's indexes.
> > Previous function_graph_enter() expects calling back from
> > prepare_ftrace_return() function which is called back only once if it is
> > enabled. But this introduces different ftrace_ops for each fgraph
> > instance and those are called from ftrace_graph_func() one by one. Thus
> > we can not loop on the fgraph_array(), and need to reuse the ret_stack
> > pushed by the previous instance. Finding the ret_stack is easy because
> > we can check the ret_stack->func. But that is not enough for the self-
> > recursive tail-call case. Thus fgraph uses the bitmap entry to find it
> > is already set (this means that entry is for previous tail call).
> >
> > Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
>
> As a heads-up, while testing the topic/fprobe-on-fgraph branch on arm64, I get
> a warning which bisets down to this commit:
Hmm, so does this happen when enabling function graph tracer?
>
> | Testing tracer function_graph:
> | ------------[ cut here ]------------
> | WARNING: CPU: 2 PID: 0 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x3c0/0x3d8
> | Modules linked in:
> | CPU: 2 PID: 0 Comm: swapper/2 Not tainted 6.7.0-rc2-00026-gea1e68a341c2 #12
> | Hardware name: linux,dummy-virt (DT)
> | pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> | pc : arch_stack_walk+0x3c0/0x3d8
> | lr : arch_stack_walk+0x260/0x3d8
> | sp : ffff80008318be00
> | x29: ffff80008318be00 x28: ffff000003c0ae80 x27: 0000000000000000
> | x26: 0000000000000000 x25: ffff000003c0ae80 x24: 0000000000000000
> | x23: ffff8000800234c8 x22: ffff80008002dc30 x21: ffff800080035d10
> | x20: ffff80008318bee8 x19: ffff800080023460 x18: ffff800083453c68
> | x17: 0000000000000000 x16: ffff800083188000 x15: 000000008ccc5058
> | x14: 0000000000000004 x13: ffff800082b8c4f0 x12: 0000000000000000
> | x11: ffff800081fba9b0 x10: ffff80008318bff0 x9 : ffff800080010798
> | x8 : ffff80008002dc30 x7 : ffff000003c0ae80 x6 : 00000000ffffffff
> | x5 : 0000000000000000 x4 : ffff8000832a3c18 x3 : ffff80008318bff0
> | x2 : ffff80008002dc30 x1 : ffff80008002dc30 x0 : ffff80008002dc30
> | Call trace:
> | arch_stack_walk+0x3c0/0x3d8
> | return_address+0x40/0x80
> | trace_hardirqs_on+0x8c/0x198
> | __do_softirq+0xe8/0x440
> | ---[ end trace 0000000000000000 ]---
>
> That's a warning in arm64's unwind_recover_return_address() function, which
> fires when ftrace_graph_ret_addr() finds return_to_handler:
>
> if (state->task->ret_stack &&
> (state->pc == (unsigned long)return_to_handler)) {
> unsigned long orig_pc;
> orig_pc = ftrace_graph_ret_addr(state->task, NULL, state->pc,
> (void *)state->fp);
> if (WARN_ON_ONCE(state->pc == orig_pc))
> return -EINVAL;
> state->pc = orig_pc;
> }
>
> The rationale there is that since tail calls are (currently) disabled on arm64,
> the only reason for ftrace_graph_ret_addr() to return return_to_handler is when
> it fails to find the original return address.
Yes. what about FP check?
>
> Does this change make it legitimate for ftrace_graph_ret_addr() to return
> return_to_handler in other cases, or is that a bug?
It should be a bug to be fixed.
>
> Either way, we'll need *some* way to recover the original return addresss...
At least it needs to dump the shadow stack so that we can analyze what
happened.
Thank you!
>
> Mark.
>
> > ---
> > Changes in v4:
> > - Simplify get_ret_stack() sanity check and use WARN_ON_ONCE() for
> > obviously wrong value.
> > - Do not check ret == return_to_handler but always read the previous
> > ret_stack in ftrace_push_return_trace() to check it is reusable.
> > - Set the bit 0 of the bitmap entry always in function_graph_enter()
> > because it uses bit 0 to check re-usability.
> > - Fix to ensure the ret_stack entry is bitmap type when checking the
> > bitmap.
> > Changes in v3:
> > - Pass current fgraph_ops to the new entry handler
> > (function_graph_enter_ops) if fgraph use ftrace.
> > - Add fgraph_ops::idx in this patch.
> > - Replace the array type with the bitmap type so that it can record
> > which fgraph is called.
> > - Fix some helper function to use passed task_struct instead of current.
> > - Reduce the ret-index size to 1024 words.
> > - Make the ret-index directly points the ret_stack.
> > - Fix ftrace_graph_ret_addr() to handle tail-call case correctly.
> > Changes in v2:
> > - Use ftrace_graph_func and FTRACE_OPS_GRAPH_STUB instead of
> > ftrace_stub and FTRACE_OPS_FL_STUB for new ftrace based fgraph.
> > ---
> > arch/arm64/kernel/ftrace.c | 19 ++
> > arch/x86/kernel/ftrace.c | 19 ++
> > include/linux/ftrace.h | 7 +
> > kernel/trace/fgraph.c | 369 ++++++++++++++++++++--------------
> > kernel/trace/ftrace.c | 6 -
> > kernel/trace/trace.h | 16 +
> > kernel/trace/trace_functions.c | 2
> > kernel/trace/trace_functions_graph.c | 8 +
> > 8 files changed, 277 insertions(+), 169 deletions(-)
> >
> > diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
> > index a650f5e11fc5..205937e04ece 100644
> > --- a/arch/arm64/kernel/ftrace.c
> > +++ b/arch/arm64/kernel/ftrace.c
> > @@ -481,7 +481,24 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
> > void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
> > struct ftrace_ops *op, struct ftrace_regs *fregs)
> > {
> > - prepare_ftrace_return(ip, &fregs->lr, fregs->fp);
> > + unsigned long *parent = &fregs->lr;
> > + struct fgraph_ops *gops = container_of(op, struct fgraph_ops, ops);
> > + int bit;
> > +
> > + if (unlikely(ftrace_graph_is_dead()))
> > + return;
> > +
> > + if (unlikely(atomic_read(¤t->tracing_graph_pause)))
> > + return;
> > +
> > + bit = ftrace_test_recursion_trylock(ip, *parent);
> > + if (bit < 0)
> > + return;
> > +
> > + if (!function_graph_enter_ops(*parent, ip, fregs->fp, parent, gops))
> > + *parent = (unsigned long)&return_to_handler;
> > +
> > + ftrace_test_recursion_unlock(bit);
> > }
> > #else
> > /*
> > diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> > index 12df54ff0e81..845e29b4254f 100644
> > --- a/arch/x86/kernel/ftrace.c
> > +++ b/arch/x86/kernel/ftrace.c
> > @@ -657,9 +657,24 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
> > struct ftrace_ops *op, struct ftrace_regs *fregs)
> > {
> > struct pt_regs *regs = &fregs->regs;
> > - unsigned long *stack = (unsigned long *)kernel_stack_pointer(regs);
> > + unsigned long *parent = (unsigned long *)kernel_stack_pointer(regs);
> > + struct fgraph_ops *gops = container_of(op, struct fgraph_ops, ops);
> > + int bit;
> > +
> > + if (unlikely(ftrace_graph_is_dead()))
> > + return;
> > +
> > + if (unlikely(atomic_read(¤t->tracing_graph_pause)))
> > + return;
> >
> > - prepare_ftrace_return(ip, (unsigned long *)stack, 0);
> > + bit = ftrace_test_recursion_trylock(ip, *parent);
> > + if (bit < 0)
> > + return;
> > +
> > + if (!function_graph_enter_ops(*parent, ip, 0, parent, gops))
> > + *parent = (unsigned long)&return_to_handler;
> > +
> > + ftrace_test_recursion_unlock(bit);
> > }
> > #endif
> >
> > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> > index 7b08169aa51d..c431a33fe789 100644
> > --- a/include/linux/ftrace.h
> > +++ b/include/linux/ftrace.h
> > @@ -1070,7 +1070,9 @@ extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph
> > struct fgraph_ops {
> > trace_func_graph_ent_t entryfunc;
> > trace_func_graph_ret_t retfunc;
> > + struct ftrace_ops ops; /* for the hash lists */
> > void *private;
> > + int idx;
> > };
> >
> > /*
> > @@ -1104,6 +1106,11 @@ extern int
> > function_graph_enter(unsigned long ret, unsigned long func,
> > unsigned long frame_pointer, unsigned long *retp);
> >
> > +extern int
> > +function_graph_enter_ops(unsigned long ret, unsigned long func,
> > + unsigned long frame_pointer, unsigned long *retp,
> > + struct fgraph_ops *gops);
> > +
> > struct ftrace_ret_stack *
> > ftrace_graph_get_ret_stack(struct task_struct *task, int idx);
> >
> > diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> > index 62c35d6d95f9..6f537ebd3ed7 100644
> > --- a/kernel/trace/fgraph.c
> > +++ b/kernel/trace/fgraph.c
> > @@ -7,6 +7,7 @@
> > *
> > * Highly modified by Steven Rostedt (VMware).
> > */
> > +#include <linux/bits.h>
> > #include <linux/jump_label.h>
> > #include <linux/suspend.h>
> > #include <linux/ftrace.h>
> > @@ -17,22 +18,15 @@
> > #include "ftrace_internal.h"
> > #include "trace.h"
> >
> > -#ifdef CONFIG_DYNAMIC_FTRACE
> > -#define ASSIGN_OPS_HASH(opsname, val) \
> > - .func_hash = val, \
> > - .local_hash.regex_lock = __MUTEX_INITIALIZER(opsname.local_hash.regex_lock),
> > -#else
> > -#define ASSIGN_OPS_HASH(opsname, val)
> > -#endif
> > -
> > #define FGRAPH_RET_SIZE sizeof(struct ftrace_ret_stack)
> > #define FGRAPH_RET_INDEX (FGRAPH_RET_SIZE / sizeof(long))
> >
> > /*
> > * On entry to a function (via function_graph_enter()), a new ftrace_ret_stack
> > - * is allocated on the task's ret_stack, then each fgraph_ops on the
> > - * fgraph_array[]'s entryfunc is called and if that returns non-zero, the
> > - * index into the fgraph_array[] for that fgraph_ops is added to the ret_stack.
> > + * is allocated on the task's ret_stack with indexes entry, then each
> > + * fgraph_ops on the fgraph_array[]'s entryfunc is called and if that returns
> > + * non-zero, the index into the fgraph_array[] for that fgraph_ops is recorded
> > + * on the indexes entry as a bit flag.
> > * As the associated ftrace_ret_stack saved for those fgraph_ops needs to
> > * be found, the index to it is also added to the ret_stack along with the
> > * index of the fgraph_array[] to each fgraph_ops that needs their retfunc
> > @@ -42,61 +36,59 @@
> > * to the last ftrace_ret_stack saved. All references to the
> > * ftrace_ret_stack has the format of:
> > *
> > - * bits: 0 - 13 Index in words from the previous ftrace_ret_stack
> > - * bits: 14 - 15 Type of storage
> > + * bits: 0 - 9 offset in words from the previous ftrace_ret_stack
> > + * (bitmap type should have FGRAPH_RET_INDEX always)
> > + * bits: 10 - 11 Type of storage
> > * 0 - reserved
> > - * 1 - fgraph_array index
> > - * For fgraph_array_index:
> > - * bits: 16 - 23 The fgraph_ops fgraph_array index
> > + * 1 - bitmap of fgraph_array index
> > + *
> > + * For bitmap of fgraph_array index
> > + * bits: 12 - 27 The bitmap of fgraph_ops fgraph_array index
> > *
> > * That is, at the end of function_graph_enter, if the first and forth
> > * fgraph_ops on the fgraph_array[] (index 0 and 3) needs their retfunc called
> > * on the return of the function being traced, this is what will be on the
> > * task's shadow ret_stack: (the stack grows upward)
> > *
> > - * | | <- task->curr_ret_stack
> > - * +----------------------------------+
> > - * | (3 << FGRAPH_ARRAY_SHIFT)|(2) | ( 3 for index of fourth fgraph_ops)
> > - * +----------------------------------+
> > - * | (0 << FGRAPH_ARRAY_SHIFT)|(1) | ( 0 for index of first fgraph_ops)
> > - * +----------------------------------+
> > - * | struct ftrace_ret_stack |
> > - * | (stores the saved ret pointer) |
> > - * +----------------------------------+
> > - * | (X) | (N) | ( N words away from previous ret_stack)
> > - * | |
> > + * | | <- task->curr_ret_stack
> > + * +--------------------------------------------+
> > + * | bitmap_type(bitmap:(BIT(3)|BIT(0)), |
> > + * | offset:FGRAPH_RET_INDEX) | <- the offset is from here
> > + * +--------------------------------------------+
> > + * | struct ftrace_ret_stack |
> > + * | (stores the saved ret pointer) | <- the offset points here
> > + * +--------------------------------------------+
> > + * | (X) | (N) | ( N words away from
> > + * | | previous ret_stack)
> > *
> > * If a backtrace is required, and the real return pointer needs to be
> > * fetched, then it looks at the task's curr_ret_stack index, if it
> > - * is greater than zero, it would subtact one, and then mask the value
> > - * on the ret_stack by FGRAPH_RET_INDEX_MASK and subtract FGRAPH_RET_INDEX
> > - * from that, to get the index of the ftrace_ret_stack structure stored
> > - * on the shadow stack.
> > + * is greater than zero (reserved, or right before poped), it would mask
> > + * the value by FGRAPH_RET_INDEX_MASK to get the offset index of the
> > + * ftrace_ret_stack structure stored on the shadow stack.
> > */
> >
> > -#define FGRAPH_RET_INDEX_SIZE 14
> > -#define FGRAPH_RET_INDEX_MASK ((1 << FGRAPH_RET_INDEX_SIZE) - 1)
> > -
> > +#define FGRAPH_RET_INDEX_SIZE 10
> > +#define FGRAPH_RET_INDEX_MASK GENMASK(FGRAPH_RET_INDEX_SIZE - 1, 0)
> >
> > #define FGRAPH_TYPE_SIZE 2
> > -#define FGRAPH_TYPE_MASK ((1 << FGRAPH_TYPE_SIZE) - 1)
> > +#define FGRAPH_TYPE_MASK GENMASK(FGRAPH_TYPE_SIZE - 1, 0)
> > #define FGRAPH_TYPE_SHIFT FGRAPH_RET_INDEX_SIZE
> >
> > enum {
> > FGRAPH_TYPE_RESERVED = 0,
> > - FGRAPH_TYPE_ARRAY = 1,
> > + FGRAPH_TYPE_BITMAP = 1,
> > };
> >
> > -#define FGRAPH_ARRAY_SIZE 16
> > -#define FGRAPH_ARRAY_MASK ((1 << FGRAPH_ARRAY_SIZE) - 1)
> > -#define FGRAPH_ARRAY_SHIFT (FGRAPH_TYPE_SHIFT + FGRAPH_TYPE_SIZE)
> > +#define FGRAPH_INDEX_SIZE 16
> > +#define FGRAPH_INDEX_MASK GENMASK(FGRAPH_INDEX_SIZE - 1, 0)
> > +#define FGRAPH_INDEX_SHIFT (FGRAPH_TYPE_SHIFT + FGRAPH_TYPE_SIZE)
> >
> > /* Currently the max stack index can't be more than register callers */
> > -#define FGRAPH_MAX_INDEX FGRAPH_ARRAY_SIZE
> > +#define FGRAPH_MAX_INDEX (FGRAPH_INDEX_SIZE + FGRAPH_RET_INDEX)
> > +
> > +#define FGRAPH_ARRAY_SIZE FGRAPH_INDEX_SIZE
> >
> > -#define FGRAPH_FRAME_SIZE (FGRAPH_RET_SIZE + FGRAPH_ARRAY_SIZE * (sizeof(long)))
> > -#define FGRAPH_FRAME_INDEX (ALIGN(FGRAPH_FRAME_SIZE, \
> > - sizeof(long)) / sizeof(long))
> > #define SHADOW_STACK_SIZE (PAGE_SIZE)
> > #define SHADOW_STACK_INDEX (SHADOW_STACK_SIZE / sizeof(long))
> > /* Leave on a buffer at the end */
> > @@ -113,19 +105,36 @@ static struct fgraph_ops *fgraph_array[FGRAPH_ARRAY_SIZE];
> >
> > static inline int get_ret_stack_index(struct task_struct *t, int offset)
> > {
> > - return current->ret_stack[offset] & FGRAPH_RET_INDEX_MASK;
> > + return t->ret_stack[offset] & FGRAPH_RET_INDEX_MASK;
> > }
> >
> > static inline int get_fgraph_type(struct task_struct *t, int offset)
> > {
> > - return (current->ret_stack[offset] >> FGRAPH_TYPE_SHIFT) &
> > - FGRAPH_TYPE_MASK;
> > + return (t->ret_stack[offset] >> FGRAPH_TYPE_SHIFT) & FGRAPH_TYPE_MASK;
> > +}
> > +
> > +static inline unsigned long
> > +get_fgraph_index_bitmap(struct task_struct *t, int offset)
> > +{
> > + return (t->ret_stack[offset] >> FGRAPH_INDEX_SHIFT) & FGRAPH_INDEX_MASK;
> > }
> >
> > -static inline int get_fgraph_array(struct task_struct *t, int offset)
> > +static inline void
> > +set_fgraph_index_bitmap(struct task_struct *t, int offset, unsigned long bitmap)
> > {
> > - return (current->ret_stack[offset] >> FGRAPH_ARRAY_SHIFT) &
> > - FGRAPH_ARRAY_MASK;
> > + t->ret_stack[offset] = (bitmap << FGRAPH_INDEX_SHIFT) |
> > + (FGRAPH_TYPE_BITMAP << FGRAPH_TYPE_SHIFT) | FGRAPH_RET_INDEX;
> > +}
> > +
> > +static inline bool is_fgraph_index_set(struct task_struct *t, int offset, int idx)
> > +{
> > + return !!(get_fgraph_index_bitmap(t, offset) & BIT(idx));
> > +}
> > +
> > +static inline void
> > +add_fgraph_index_bitmap(struct task_struct *t, int offset, unsigned long bitmap)
> > +{
> > + t->ret_stack[offset] |= (bitmap << FGRAPH_INDEX_SHIFT);
> > }
> >
> > /* ftrace_graph_entry set to this to tell some archs to run function graph */
> > @@ -160,17 +169,14 @@ get_ret_stack(struct task_struct *t, int offset, int *index)
> >
> > BUILD_BUG_ON(FGRAPH_RET_SIZE % sizeof(long));
> >
> > - if (offset <= 0)
> > + if (unlikely(offset <= 0))
> > return NULL;
> >
> > - idx = get_ret_stack_index(t, offset - 1);
> > -
> > - if (idx <= 0 || idx > FGRAPH_MAX_INDEX)
> > + idx = get_ret_stack_index(t, --offset);
> > + if (WARN_ON_ONCE(idx <= 0 || idx > offset))
> > return NULL;
> >
> > - offset -= idx + FGRAPH_RET_INDEX;
> > - if (offset < 0)
> > - return NULL;
> > + offset -= idx;
> >
> > *index = offset;
> > return RET_STACK(t, offset);
> > @@ -231,10 +237,12 @@ void ftrace_graph_stop(void)
> > /* Add a function return address to the trace stack on thread info.*/
> > static int
> > ftrace_push_return_trace(unsigned long ret, unsigned long func,
> > - unsigned long frame_pointer, unsigned long *retp)
> > + unsigned long frame_pointer, unsigned long *retp,
> > + int fgraph_idx)
> > {
> > struct ftrace_ret_stack *ret_stack;
> > unsigned long long calltime;
> > + unsigned long val;
> > int index;
> >
> > if (unlikely(ftrace_graph_is_dead()))
> > @@ -243,6 +251,21 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> > if (!current->ret_stack)
> > return -EBUSY;
> >
> > + /*
> > + * At first, check whether the previous fgraph callback is pushed by
> > + * the fgraph on the same function entry.
> > + * But if @func is the self tail-call function, we also need to ensure
> > + * the ret_stack is not for the previous call by checking whether the
> > + * bit of @fgraph_idx is set or not.
> > + */
> > + ret_stack = get_ret_stack(current, current->curr_ret_stack, &index);
> > + if (ret_stack && ret_stack->func == func &&
> > + get_fgraph_type(current, index + FGRAPH_RET_INDEX) == FGRAPH_TYPE_BITMAP &&
> > + !is_fgraph_index_set(current, index + FGRAPH_RET_INDEX, fgraph_idx))
> > + return index + FGRAPH_RET_INDEX;
> > +
> > + val = (FGRAPH_TYPE_RESERVED << FGRAPH_TYPE_SHIFT) | FGRAPH_RET_INDEX;
> > +
> > BUILD_BUG_ON(SHADOW_STACK_SIZE % sizeof(long));
> >
> > /*
> > @@ -252,17 +275,19 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> > smp_rmb();
> >
> > /* The return trace stack is full */
> > - if (current->curr_ret_stack >= SHADOW_STACK_MAX_INDEX) {
> > + if (current->curr_ret_stack + FGRAPH_RET_INDEX >= SHADOW_STACK_MAX_INDEX) {
> > atomic_inc(¤t->trace_overrun);
> > return -EBUSY;
> > }
> >
> > calltime = trace_clock_local();
> >
> > - index = current->curr_ret_stack;
> > - /* ret offset = 1 ; type = reserved */
> > - current->ret_stack[index + FGRAPH_RET_INDEX] = 1;
> > + index = READ_ONCE(current->curr_ret_stack);
> > ret_stack = RET_STACK(current, index);
> > + index += FGRAPH_RET_INDEX;
> > +
> > + /* ret offset = FGRAPH_RET_INDEX ; type = reserved */
> > + current->ret_stack[index] = val;
> > ret_stack->ret = ret;
> > /*
> > * The unwinders expect curr_ret_stack to point to either zero
> > @@ -278,7 +303,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> > * at least a correct index!
> > */
> > barrier();
> > - current->curr_ret_stack += FGRAPH_RET_INDEX + 1;
> > + current->curr_ret_stack = index + 1;
> > /*
> > * This next barrier is to ensure that an interrupt coming in
> > * will not corrupt what we are about to write.
> > @@ -286,7 +311,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> > barrier();
> >
> > /* Still keep it reserved even if an interrupt came in */
> > - current->ret_stack[index + FGRAPH_RET_INDEX] = 1;
> > + current->ret_stack[index] = val;
> >
> > ret_stack->ret = ret;
> > ret_stack->func = func;
> > @@ -297,7 +322,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> > #ifdef HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
> > ret_stack->retp = retp;
> > #endif
> > - return 0;
> > + return index;
> > }
> >
> > /*
> > @@ -314,15 +339,13 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
> > # define MCOUNT_INSN_SIZE 0
> > #endif
> >
> > +/* If the caller does not use ftrace, call this function. */
> > int function_graph_enter(unsigned long ret, unsigned long func,
> > unsigned long frame_pointer, unsigned long *retp)
> > {
> > struct ftrace_graph_ent trace;
> > - int offset;
> > - int start;
> > - int type;
> > - int val;
> > - int cnt = 0;
> > + unsigned long bitmap = 0;
> > + int index;
> > int i;
> >
> > #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
> > @@ -337,69 +360,33 @@ int function_graph_enter(unsigned long ret, unsigned long func,
> > return -EBUSY;
> > #endif
> >
> > - if (!ftrace_ops_test(&global_ops, func, NULL))
> > - return -EBUSY;
> > -
> > trace.func = func;
> > trace.depth = ++current->curr_ret_depth;
> >
> > - if (ftrace_push_return_trace(ret, func, frame_pointer, retp))
> > + index = ftrace_push_return_trace(ret, func, frame_pointer, retp, 0);
> > + if (index < 0)
> > goto out;
> >
> > - /* Use start for the distance to ret_stack (skipping over reserve) */
> > - start = offset = current->curr_ret_stack - 2;
> > -
> > for (i = 0; i < fgraph_array_cnt; i++) {
> > struct fgraph_ops *gops = fgraph_array[i];
> >
> > if (gops == &fgraph_stub)
> > continue;
> >
> > - if ((offset == start) &&
> > - (current->curr_ret_stack >= SHADOW_STACK_INDEX - 1)) {
> > - atomic_inc(¤t->trace_overrun);
> > - break;
> > - }
> > - if (fgraph_array[i]->entryfunc(&trace, fgraph_array[i])) {
> > - offset = current->curr_ret_stack;
> > - /* Check the top level stored word */
> > - type = get_fgraph_type(current, offset - 1);
> > -
> > - val = (i << FGRAPH_ARRAY_SHIFT) |
> > - (FGRAPH_TYPE_ARRAY << FGRAPH_TYPE_SHIFT) |
> > - ((offset - start) - 1);
> > -
> > - /* We can reuse the top word if it is reserved */
> > - if (type == FGRAPH_TYPE_RESERVED) {
> > - current->ret_stack[offset - 1] = val;
> > - cnt++;
> > - continue;
> > - }
> > - val++;
> > -
> > - current->ret_stack[offset] = val;
> > - /*
> > - * Write the value before we increment, so that
> > - * if an interrupt comes in after we increment
> > - * it will still see the value and skip over
> > - * this.
> > - */
> > - barrier();
> > - current->curr_ret_stack++;
> > - /*
> > - * Have to write again, in case an interrupt
> > - * came in before the increment and after we
> > - * wrote the value.
> > - */
> > - barrier();
> > - current->ret_stack[offset] = val;
> > - cnt++;
> > - }
> > + if (ftrace_ops_test(&gops->ops, func, NULL) &&
> > + gops->entryfunc(&trace, gops))
> > + bitmap |= BIT(i);
> > }
> >
> > - if (!cnt)
> > + if (!bitmap)
> > goto out_ret;
> >
> > + /*
> > + * Since this function uses fgraph_idx = 0 as a tail-call checking
> > + * flag, set that bit always.
> > + */
> > + set_fgraph_index_bitmap(current, index, bitmap | BIT(0));
> > +
> > return 0;
> > out_ret:
> > current->curr_ret_stack -= FGRAPH_RET_INDEX + 1;
> > @@ -408,15 +395,51 @@ int function_graph_enter(unsigned long ret, unsigned long func,
> > return -EBUSY;
> > }
> >
> > +/* This is called from ftrace_graph_func() via ftrace */
> > +int function_graph_enter_ops(unsigned long ret, unsigned long func,
> > + unsigned long frame_pointer, unsigned long *retp,
> > + struct fgraph_ops *gops)
> > +{
> > + struct ftrace_graph_ent trace;
> > + int index;
> > + int type;
> > +
> > +
> > + /* Use start for the distance to ret_stack (skipping over reserve) */
> > + index = ftrace_push_return_trace(ret, func, frame_pointer, retp, gops->idx);
> > + if (index < 0)
> > + return index;
> > + type = get_fgraph_type(current, index);
> > +
> > + /* This is the first ret_stack for this fentry */
> > + if (type == FGRAPH_TYPE_RESERVED)
> > + ++current->curr_ret_depth;
> > +
> > + trace.func = func;
> > + trace.depth = current->curr_ret_depth;
> > + if (gops->entryfunc(&trace, gops)) {
> > + if (type == FGRAPH_TYPE_RESERVED)
> > + set_fgraph_index_bitmap(current, index, BIT(gops->idx));
> > + else
> > + add_fgraph_index_bitmap(current, index, BIT(gops->idx));
> > + return 0;
> > + }
> > +
> > + if (type == FGRAPH_TYPE_RESERVED) {
> > + current->curr_ret_stack -= FGRAPH_RET_INDEX + 1;
> > + current->curr_ret_depth--;
> > + }
> > + return -EBUSY;
> > +}
> > +
> > /* Retrieve a function return address to the trace stack on thread info.*/
> > static struct ftrace_ret_stack *
> > ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
> > - unsigned long frame_pointer)
> > + unsigned long frame_pointer, int *index)
> > {
> > struct ftrace_ret_stack *ret_stack;
> > - int index;
> >
> > - ret_stack = get_ret_stack(current, current->curr_ret_stack, &index);
> > + ret_stack = get_ret_stack(current, current->curr_ret_stack, index);
> >
> > if (unlikely(!ret_stack)) {
> > ftrace_graph_stop();
> > @@ -455,6 +478,7 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
> > }
> > #endif
> >
> > + *index += FGRAPH_RET_INDEX;
> > *ret = ret_stack->ret;
> > trace->func = ret_stack->func;
> > trace->calltime = ret_stack->calltime;
> > @@ -507,13 +531,12 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
> > {
> > struct ftrace_ret_stack *ret_stack;
> > struct ftrace_graph_ret trace;
> > + unsigned long bitmap;
> > unsigned long ret;
> > - int offset;
> > int index;
> > - int idx;
> > int i;
> >
> > - ret_stack = ftrace_pop_return_trace(&trace, &ret, frame_pointer);
> > + ret_stack = ftrace_pop_return_trace(&trace, &ret, frame_pointer, &index);
> >
> > if (unlikely(!ret_stack)) {
> > ftrace_graph_stop();
> > @@ -527,16 +550,17 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
> > trace.retval = fgraph_ret_regs_return_value(ret_regs);
> > #endif
> >
> > - offset = current->curr_ret_stack - 1;
> > - index = get_ret_stack_index(current, offset);
> > + bitmap = get_fgraph_index_bitmap(current, index);
> > + for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) {
> > + struct fgraph_ops *gops = fgraph_array[i];
> >
> > - /* index has to be at least one! Optimize for it */
> > - i = 0;
> > - do {
> > - idx = get_fgraph_array(current, offset - i);
> > - fgraph_array[idx]->retfunc(&trace, fgraph_array[idx]);
> > - i++;
> > - } while (i < index);
> > + if (!(bitmap & BIT(i)))
> > + continue;
> > + if (gops == &fgraph_stub)
> > + continue;
> > +
> > + gops->retfunc(&trace, gops);
> > + }
> >
> > /*
> > * The ftrace_graph_return() may still access the current
> > @@ -544,7 +568,7 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
> > * curr_ret_stack is after that.
> > */
> > barrier();
> > - current->curr_ret_stack -= index + FGRAPH_RET_INDEX;
> > + current->curr_ret_stack -= FGRAPH_RET_INDEX + 1;
> > current->curr_ret_depth--;
> > return ret;
> > }
> > @@ -622,7 +646,17 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
> > ret_stack = get_ret_stack(current, i, &i);
> > if (!ret_stack)
> > break;
> > - if (ret_stack->retp == retp)
> > + /*
> > + * For the tail-call, there would be 2 or more ftrace_ret_stacks on
> > + * the ret_stack, which records "return_to_handler" as the return
> > + * address excpt for the last one.
> > + * But on the real stack, there should be 1 entry because tail-call
> > + * reuses the return address on the stack and jump to the next function.
> > + * Thus we will continue to find real return address.
> > + */
> > + if (ret_stack->retp == retp &&
> > + ret_stack->ret !=
> > + (unsigned long)dereference_kernel_function_descriptor(return_to_handler))
> > return ret_stack->ret;
> > }
> >
> > @@ -645,6 +679,9 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
> > i = *idx;
> > do {
> > ret_stack = get_ret_stack(task, task_idx, &task_idx);
> > + if (ret_stack && ret_stack->ret ==
> > + (unsigned long)dereference_kernel_function_descriptor(return_to_handler))
> > + continue;
> > i--;
> > } while (i >= 0 && ret_stack);
> >
> > @@ -655,17 +692,25 @@ unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
> > }
> > #endif /* HAVE_FUNCTION_GRAPH_RET_ADDR_PTR */
> >
> > -static struct ftrace_ops graph_ops = {
> > - .func = ftrace_graph_func,
> > - .flags = FTRACE_OPS_FL_INITIALIZED |
> > - FTRACE_OPS_FL_PID |
> > - FTRACE_OPS_GRAPH_STUB,
> > +void fgraph_init_ops(struct ftrace_ops *dst_ops,
> > + struct ftrace_ops *src_ops)
> > +{
> > + dst_ops->func = ftrace_graph_func;
> > + dst_ops->flags = FTRACE_OPS_FL_PID | FTRACE_OPS_GRAPH_STUB;
> > +
> > #ifdef FTRACE_GRAPH_TRAMP_ADDR
> > - .trampoline = FTRACE_GRAPH_TRAMP_ADDR,
> > + dst_ops->trampoline = FTRACE_GRAPH_TRAMP_ADDR;
> > /* trampoline_size is only needed for dynamically allocated tramps */
> > #endif
> > - ASSIGN_OPS_HASH(graph_ops, &global_ops.local_hash)
> > -};
> > +
> > +#ifdef CONFIG_DYNAMIC_FTRACE
> > + if (src_ops) {
> > + dst_ops->func_hash = &src_ops->local_hash;
> > + mutex_init(&dst_ops->local_hash.regex_lock);
> > + dst_ops->flags |= FTRACE_OPS_FL_INITIALIZED;
> > + }
> > +#endif
> > +}
> >
> > void ftrace_graph_sleep_time_control(bool enable)
> > {
> > @@ -869,11 +914,20 @@ static int start_graph_tracing(void)
> >
> > int register_ftrace_graph(struct fgraph_ops *gops)
> > {
> > + int command = 0;
> > int ret = 0;
> > int i;
> >
> > mutex_lock(&ftrace_lock);
> >
> > + if (!gops->ops.func) {
> > + gops->ops.flags |= FTRACE_OPS_GRAPH_STUB;
> > + gops->ops.func = ftrace_graph_func;
> > +#ifdef FTRACE_GRAPH_TRAMP_ADDR
> > + gops->ops.trampoline = FTRACE_GRAPH_TRAMP_ADDR;
> > +#endif
> > + }
> > +
> > if (!fgraph_array[0]) {
> > /* The array must always have real data on it */
> > for (i = 0; i < FGRAPH_ARRAY_SIZE; i++)
> > @@ -893,6 +947,7 @@ int register_ftrace_graph(struct fgraph_ops *gops)
> > fgraph_array[i] = gops;
> > if (i + 1 > fgraph_array_cnt)
> > fgraph_array_cnt = i + 1;
> > + gops->idx = i;
> >
> > ftrace_graph_active++;
> >
> > @@ -909,9 +964,10 @@ int register_ftrace_graph(struct fgraph_ops *gops)
> > */
> > ftrace_graph_return = return_run;
> > ftrace_graph_entry = entry_run;
> > -
> > - ret = ftrace_startup(&graph_ops, FTRACE_START_FUNC_RET);
> > + command = FTRACE_START_FUNC_RET;
> > }
> > +
> > + ret = ftrace_startup(&gops->ops, command);
> > out:
> > mutex_unlock(&ftrace_lock);
> > return ret;
> > @@ -919,6 +975,7 @@ int register_ftrace_graph(struct fgraph_ops *gops)
> >
> > void unregister_ftrace_graph(struct fgraph_ops *gops)
> > {
> > + int command = 0;
> > int i;
> >
> > mutex_lock(&ftrace_lock);
> > @@ -926,25 +983,29 @@ void unregister_ftrace_graph(struct fgraph_ops *gops)
> > if (unlikely(!ftrace_graph_active))
> > goto out;
> >
> > - for (i = 0; i < fgraph_array_cnt; i++)
> > - if (gops == fgraph_array[i])
> > - break;
> > - if (i >= fgraph_array_cnt)
> > + if (unlikely(gops->idx < 0 || gops->idx >= fgraph_array_cnt))
> > goto out;
> >
> > - fgraph_array[i] = &fgraph_stub;
> > - if (i + 1 == fgraph_array_cnt) {
> > - for (; i >= 0; i--)
> > - if (fgraph_array[i] != &fgraph_stub)
> > - break;
> > + WARN_ON_ONCE(fgraph_array[gops->idx] != gops);
> > +
> > + fgraph_array[gops->idx] = &fgraph_stub;
> > + if (gops->idx + 1 == fgraph_array_cnt) {
> > + i = gops->idx;
> > + while (i >= 0 && fgraph_array[i] == &fgraph_stub)
> > + i--;
> > fgraph_array_cnt = i + 1;
> > }
> >
> > ftrace_graph_active--;
> > +
> > + if (!ftrace_graph_active)
> > + command = FTRACE_STOP_FUNC_RET;
> > +
> > + ftrace_shutdown(&gops->ops, command);
> > +
> > if (!ftrace_graph_active) {
> > ftrace_graph_return = ftrace_stub_graph;
> > ftrace_graph_entry = ftrace_graph_entry_stub;
> > - ftrace_shutdown(&graph_ops, FTRACE_STOP_FUNC_RET);
> > unregister_pm_notifier(&ftrace_suspend_notifier);
> > unregister_trace_sched_switch(ftrace_graph_probe_sched_switch, NULL);
> > }
> > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
> > index 83fbfb7b48f8..c4cc2a9d0047 100644
> > --- a/kernel/trace/ftrace.c
> > +++ b/kernel/trace/ftrace.c
> > @@ -3050,6 +3050,8 @@ int ftrace_startup(struct ftrace_ops *ops, int command)
> > if (unlikely(ftrace_disabled))
> > return -ENODEV;
> >
> > + ftrace_ops_init(ops);
> > +
> > ret = __register_ftrace_function(ops);
> > if (ret)
> > return ret;
> > @@ -7319,7 +7321,7 @@ __init void ftrace_init_global_array_ops(struct trace_array *tr)
> > tr->ops = &global_ops;
> > tr->ops->private = tr;
> > ftrace_init_trace_array(tr);
> > - init_array_fgraph_ops(tr);
> > + init_array_fgraph_ops(tr, tr->ops);
> > }
> >
> > void ftrace_init_array_ops(struct trace_array *tr, ftrace_func_t func)
> > @@ -8051,7 +8053,7 @@ static int register_ftrace_function_nolock(struct ftrace_ops *ops)
> > */
> > int register_ftrace_function(struct ftrace_ops *ops)
> > {
> > - int ret;
> > + int ret = -1;
> >
> > lock_direct_mutex();
> > ret = prepare_direct_functions_for_ipmodify(ops);
> > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> > index 16948c0ed00a..02edfdb68933 100644
> > --- a/kernel/trace/trace.h
> > +++ b/kernel/trace/trace.h
> > @@ -890,8 +890,8 @@ extern int __trace_graph_entry(struct trace_array *tr,
> > extern void __trace_graph_return(struct trace_array *tr,
> > struct ftrace_graph_ret *trace,
> > unsigned int trace_ctx);
> > -extern void init_array_fgraph_ops(struct trace_array *tr);
> > -extern int allocate_fgraph_ops(struct trace_array *tr);
> > +extern void init_array_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops);
> > +extern int allocate_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops);
> > extern void free_fgraph_ops(struct trace_array *tr);
> >
> > #ifdef CONFIG_DYNAMIC_FTRACE
> > @@ -974,6 +974,7 @@ static inline int ftrace_graph_notrace_addr(unsigned long addr)
> > preempt_enable_notrace();
> > return ret;
> > }
> > +
> > #else
> > static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
> > {
> > @@ -999,18 +1000,19 @@ static inline bool ftrace_graph_ignore_func(struct ftrace_graph_ent *trace)
> > (fgraph_max_depth && trace->depth >= fgraph_max_depth);
> > }
> >
> > +void fgraph_init_ops(struct ftrace_ops *dst_ops,
> > + struct ftrace_ops *src_ops);
> > +
> > #else /* CONFIG_FUNCTION_GRAPH_TRACER */
> > static inline enum print_line_t
> > print_graph_function_flags(struct trace_iterator *iter, u32 flags)
> > {
> > return TRACE_TYPE_UNHANDLED;
> > }
> > -static inline void init_array_fgraph_ops(struct trace_array *tr) { }
> > -static inline int allocate_fgraph_ops(struct trace_array *tr)
> > -{
> > - return 0;
> > -}
> > static inline void free_fgraph_ops(struct trace_array *tr) { }
> > +/* ftrace_ops may not be defined */
> > +#define init_array_fgraph_ops(tr, ops) do { } while (0)
> > +#define allocate_fgraph_ops(tr, ops) ({ 0; })
> > #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
> >
> > extern struct list_head ftrace_pids;
> > diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
> > index 8e8da0d0ee52..13bf2415245d 100644
> > --- a/kernel/trace/trace_functions.c
> > +++ b/kernel/trace/trace_functions.c
> > @@ -91,7 +91,7 @@ int ftrace_create_function_files(struct trace_array *tr,
> > if (!tr->ops)
> > return -EINVAL;
> >
> > - ret = allocate_fgraph_ops(tr);
> > + ret = allocate_fgraph_ops(tr, tr->ops);
> > if (ret) {
> > kfree(tr->ops);
> > return ret;
> > diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
> > index 9ccc904a7703..7f30652f0e97 100644
> > --- a/kernel/trace/trace_functions_graph.c
> > +++ b/kernel/trace/trace_functions_graph.c
> > @@ -288,7 +288,7 @@ static struct fgraph_ops funcgraph_ops = {
> > .retfunc = &trace_graph_return,
> > };
> >
> > -int allocate_fgraph_ops(struct trace_array *tr)
> > +int allocate_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops)
> > {
> > struct fgraph_ops *gops;
> >
> > @@ -301,6 +301,9 @@ int allocate_fgraph_ops(struct trace_array *tr)
> >
> > tr->gops = gops;
> > gops->private = tr;
> > +
> > + fgraph_init_ops(&gops->ops, ops);
> > +
> > return 0;
> > }
> >
> > @@ -309,10 +312,11 @@ void free_fgraph_ops(struct trace_array *tr)
> > kfree(tr->gops);
> > }
> >
> > -__init void init_array_fgraph_ops(struct trace_array *tr)
> > +__init void init_array_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops)
> > {
> > tr->gops = &funcgraph_ops;
> > funcgraph_ops.private = tr;
> > + fgraph_init_ops(&tr->gops->ops, ops);
> > }
> >
> > static int graph_trace_init(struct trace_array *tr)
> >
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 56+ messages in thread* Re: [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering
2024-01-08 1:14 ` Masami Hiramatsu
@ 2024-01-08 12:25 ` Mark Rutland
2024-01-08 14:21 ` Mark Rutland
2024-01-11 2:15 ` Masami Hiramatsu
0 siblings, 2 replies; 56+ messages in thread
From: Mark Rutland @ 2024-01-08 12:25 UTC (permalink / raw)
To: Masami Hiramatsu
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Peter Zijlstra, Thomas Gleixner,
Guo Ren
Hi,
There's a bit more of an info-dump below; I'll go try to dump the fgraph shadow
stack so that we can analyse this in more detail.
On Mon, Jan 08, 2024 at 10:14:36AM +0900, Masami Hiramatsu wrote:
> On Fri, 5 Jan 2024 17:09:10 +0000
> Mark Rutland <mark.rutland@arm.com> wrote:
>
> > On Mon, Dec 18, 2023 at 10:13:46PM +0900, Masami Hiramatsu (Google) wrote:
> > > From: Steven Rostedt (VMware) <rostedt@goodmis.org>
> > >
> > > Allow for instances to have their own ftrace_ops part of the fgraph_ops
> > > that makes the funtion_graph tracer filter on the set_ftrace_filter file
> > > of the instance and not the top instance.
> > >
> > > This also change how the function_graph handles multiple instances on the
> > > shadow stack. Previously we use ARRAY type entries to record which one
> > > is enabled, and this makes it a bitmap of the fgraph_array's indexes.
> > > Previous function_graph_enter() expects calling back from
> > > prepare_ftrace_return() function which is called back only once if it is
> > > enabled. But this introduces different ftrace_ops for each fgraph
> > > instance and those are called from ftrace_graph_func() one by one. Thus
> > > we can not loop on the fgraph_array(), and need to reuse the ret_stack
> > > pushed by the previous instance. Finding the ret_stack is easy because
> > > we can check the ret_stack->func. But that is not enough for the self-
> > > recursive tail-call case. Thus fgraph uses the bitmap entry to find it
> > > is already set (this means that entry is for previous tail call).
> > >
> > > Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> >
> > As a heads-up, while testing the topic/fprobe-on-fgraph branch on arm64, I get
> > a warning which bisets down to this commit:
>
> Hmm, so does this happen when enabling function graph tracer?
Yes; I see it during the function_graph boot-time self-test if I also enable
CONFIG_IRQSOFF_TRACER=y. I can also trigger it regardless of
CONFIG_IRQSOFF_TRACER if I cat /proc/self/stack with the function_graph tracer
enabled (note that I hacked the unwinder to continue after failing to recover a
return address):
| # mount -t tracefs none /sys/kernel/tracing/
| # echo function_graph > /sys/kernel/tracing/current_tracer
| # cat /proc/self/stack
| [ 37.469980] ------------[ cut here ]------------
| [ 37.471503] WARNING: CPU: 2 PID: 174 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x2d8/0x338
| [ 37.474381] Modules linked in:
| [ 37.475501] CPU: 2 PID: 174 Comm: cat Not tainted 6.7.0-rc2-00026-gea1e68a341c2-dirty #15
| [ 37.478133] Hardware name: linux,dummy-virt (DT)
| [ 37.479670] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
| [ 37.481923] pc : arch_stack_walk+0x2d8/0x338
| [ 37.483373] lr : arch_stack_walk+0x1bc/0x338
| [ 37.484818] sp : ffff8000835f3a90
| [ 37.485974] x29: ffff8000835f3a90 x28: ffff8000835f3b80 x27: ffff8000835f3b38
| [ 37.488405] x26: ffff000004341e00 x25: ffff8000835f4000 x24: ffff80008002df18
| [ 37.490842] x23: ffff80008002df18 x22: ffff8000835f3b60 x21: ffff80008015d240
| [ 37.493269] x20: ffff8000835f3b50 x19: ffff8000835f3b40 x18: 0000000000000000
| [ 37.495704] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
| [ 37.498144] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
| [ 37.500579] x11: ffff800082b4d920 x10: ffff8000835f3a70 x9 : ffff8000800e55a0
| [ 37.503021] x8 : ffff80008002df18 x7 : ffff000004341e00 x6 : 00000000ffffffff
| [ 37.505452] x5 : 0000000000000000 x4 : ffff8000835f3e48 x3 : ffff8000835f3b80
| [ 37.507888] x2 : ffff80008002df18 x1 : ffff000007f7b000 x0 : ffff80008002df18
| [ 37.510319] Call trace:
| [ 37.511202] arch_stack_walk+0x2d8/0x338
| [ 37.512541] stack_trace_save_tsk+0x90/0x110
| [ 37.514012] return_to_handler+0x0/0x48
| [ 37.515336] return_to_handler+0x0/0x48
| [ 37.516657] return_to_handler+0x0/0x48
| [ 37.517985] return_to_handler+0x0/0x48
| [ 37.519305] return_to_handler+0x0/0x48
| [ 37.520623] return_to_handler+0x0/0x48
| [ 37.521957] return_to_handler+0x0/0x48
| [ 37.523272] return_to_handler+0x0/0x48
| [ 37.524595] return_to_handler+0x0/0x48
| [ 37.525931] return_to_handler+0x0/0x48
| [ 37.527254] return_to_handler+0x0/0x48
| [ 37.528564] el0t_64_sync_handler+0x120/0x130
| [ 37.530046] el0t_64_sync+0x190/0x198
| [ 37.531310] ---[ end trace 0000000000000000 ]---
| [<0>] ftrace_stub_graph+0x8/0x8
| [<0>] ftrace_stub_graph+0x8/0x8
| [<0>] ftrace_stub_graph+0x8/0x8
| [<0>] ftrace_stub_graph+0x8/0x8
| [<0>] ftrace_stub_graph+0x8/0x8
| [<0>] ftrace_stub_graph+0x8/0x8
| [<0>] ftrace_stub_graph+0x8/0x8
| [<0>] ftrace_stub_graph+0x8/0x8
| [<0>] ftrace_stub_graph+0x8/0x8
| [<0>] ftrace_stub_graph+0x8/0x8
| [<0>] ftrace_stub_graph+0x8/0x8
| [<0>] el0t_64_sync_handler+0x120/0x130
| [<0>] el0t_64_sync+0x190/0x198
One interesting thing there is that there are two distinct failure modes: the
unwind for the WARNING gives return_to_handler instead of the original return
address, and the unwind returned from /proc/self/stack gives ftrace_stub_graph
rather than the original return address.
> >
> > | Testing tracer function_graph:
> > | ------------[ cut here ]------------
> > | WARNING: CPU: 2 PID: 0 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x3c0/0x3d8
> > | Modules linked in:
> > | CPU: 2 PID: 0 Comm: swapper/2 Not tainted 6.7.0-rc2-00026-gea1e68a341c2 #12
> > | Hardware name: linux,dummy-virt (DT)
> > | pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > | pc : arch_stack_walk+0x3c0/0x3d8
> > | lr : arch_stack_walk+0x260/0x3d8
> > | sp : ffff80008318be00
> > | x29: ffff80008318be00 x28: ffff000003c0ae80 x27: 0000000000000000
> > | x26: 0000000000000000 x25: ffff000003c0ae80 x24: 0000000000000000
> > | x23: ffff8000800234c8 x22: ffff80008002dc30 x21: ffff800080035d10
> > | x20: ffff80008318bee8 x19: ffff800080023460 x18: ffff800083453c68
> > | x17: 0000000000000000 x16: ffff800083188000 x15: 000000008ccc5058
> > | x14: 0000000000000004 x13: ffff800082b8c4f0 x12: 0000000000000000
> > | x11: ffff800081fba9b0 x10: ffff80008318bff0 x9 : ffff800080010798
> > | x8 : ffff80008002dc30 x7 : ffff000003c0ae80 x6 : 00000000ffffffff
> > | x5 : 0000000000000000 x4 : ffff8000832a3c18 x3 : ffff80008318bff0
> > | x2 : ffff80008002dc30 x1 : ffff80008002dc30 x0 : ffff80008002dc30
> > | Call trace:
> > | arch_stack_walk+0x3c0/0x3d8
> > | return_address+0x40/0x80
> > | trace_hardirqs_on+0x8c/0x198
> > | __do_softirq+0xe8/0x440
> > | ---[ end trace 0000000000000000 ]---
With the smae hack to continue after failing to recover a return address, the
failure in the selftest looks like:
| ------------[ cut here ]------------
| WARNING: CPU: 7 PID: 0 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x2d8/0x338
| Modules linked in:
| CPU: 7 PID: 0 Comm: swapper/7 Not tainted 6.7.0-rc2-00026-gea1e68a341c2-dirty #14
| Hardware name: linux,dummy-virt (DT)
| pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
| pc : arch_stack_walk+0x2d8/0x338
| lr : arch_stack_walk+0x1bc/0x338
| sp : ffff8000830c3e20
| x29: ffff8000830c3e20 x28: ffff8000830c3ff0 x27: ffff8000830c3ec8
| x26: ffff0000037e0000 x25: ffff8000830c4000 x24: ffff80008002e080
| x23: ffff80008002e080 x22: ffff8000830c3ee8 x21: ffff800080023418
| x20: ffff8000830c3f50 x19: ffff8000830c3f40 x18: ffffffffffffffff
| x17: 0000000000000000 x16: ffff8000830c0000 x15: 0000000000000000
| x14: 0000000000000002 x13: ffff8000800360f8 x12: ffff800080028330
| x11: ffff800081f4a978 x10: ffff8000830c3ff0 x9 : ffff800080010798
| x8 : ffff80008002e080 x7 : ffff0000037e0000 x6 : 00000000ffffffff
| x5 : 0000000000000000 x4 : ffff8000831dbc18 x3 : ffff8000830c3ff0
| x2 : ffff80008002e080 x1 : ffff0000040a3000 x0 : ffff80008002e080
| Call trace:
| arch_stack_walk+0x2d8/0x338
| return_address+0x40/0x80
| trace_hardirqs_on+0x8c/0x198
| __do_softirq+0xe8/0x43c
| return_to_handler+0x0/0x48
| return_to_handler+0x0/0x48
| do_softirq_own_stack+0x24/0x38
| return_to_handler+0x0/0x48
| el1_interrupt+0x38/0x68
| el1h_64_irq_handler+0x18/0x28
| el1h_64_irq+0x64/0x68
| default_idle_call+0x70/0x178
| do_idle+0x228/0x290
| cpu_startup_entry+0x40/0x50
| secondary_start_kernel+0x138/0x160
| __secondary_switched+0xb8/0xc0
| ---[ end trace 0000000000000000 ]---
The portion of the trace with:
__do_softirq+0xe8/0x43c
return_to_handler+0x0/0x48
return_to_handler+0x0/0x48
do_softirq_own_stack+0x24/0x38
... should be something like:
__do_softirq
____do_softirq
call_on_irq_stack // asm trampoline, not traceable
do_softirq_own_stack
The generated assembly for do_softirq_own_stack(), ____do_softirq(), and
__do_softirq() is as I'd expect with no tail calls, so I can't see an obvious
reason the return address cannot be recovered correctly.
> > That's a warning in arm64's unwind_recover_return_address() function, which
> > fires when ftrace_graph_ret_addr() finds return_to_handler:
> >
> > if (state->task->ret_stack &&
> > (state->pc == (unsigned long)return_to_handler)) {
> > unsigned long orig_pc;
> > orig_pc = ftrace_graph_ret_addr(state->task, NULL, state->pc,
> > (void *)state->fp);
> > if (WARN_ON_ONCE(state->pc == orig_pc))
> > return -EINVAL;
> > state->pc = orig_pc;
> > }
> >
> > The rationale there is that since tail calls are (currently) disabled on arm64,
> > the only reason for ftrace_graph_ret_addr() to return return_to_handler is when
> > it fails to find the original return address.
>
> Yes. what about FP check?
Do you mean HAVE_FUNCTION_GRAPH_FP_TEST?
That is enabled, and there are warnings from ftrace_pop_return_trace(), so I
believe push/pop is balanced.
We also have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR, but since the return address is
not on the stack at the point function-entry is intercepted we use the FP as
the retp value -- in the absence of tail calls this will be different between a
caller and callee.
> > Does this change make it legitimate for ftrace_graph_ret_addr() to return
> > return_to_handler in other cases, or is that a bug?
>
> It should be a bug to be fixed.
Cool; thanks for confirming!
> > Either way, we'll need *some* way to recover the original return addresss...
>
> At least it needs to dump the shadow stack so that we can analyze what
> happened.
Sounds like a plan; as above I'll have a go at putting that together and will
dump the results here.
Thanks for the help! :)
Mark.
^ permalink raw reply [flat|nested] 56+ messages in thread* Re: [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering
2024-01-08 12:25 ` Mark Rutland
@ 2024-01-08 14:21 ` Mark Rutland
2024-01-08 15:03 ` Mark Rutland
2024-01-11 2:15 ` Masami Hiramatsu
1 sibling, 1 reply; 56+ messages in thread
From: Mark Rutland @ 2024-01-08 14:21 UTC (permalink / raw)
To: Masami Hiramatsu
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Mon, Jan 08, 2024 at 12:25:55PM +0000, Mark Rutland wrote:
> We also have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR, but since the return address is
> not on the stack at the point function-entry is intercepted we use the FP as
> the retp value -- in the absence of tail calls this will be different between a
> caller and callee.
Ah; I just spotted that this patch changed that in ftrace_graph_func(), which
is the source of the bug.
As of this patch, we use the address of fregs->lr as the retp value, but the
unwinder still uses the FP value, and so when unwind_recover_return_address()
calls ftrace_graph_ret_addr(), the retp value won't match the expected entry on
the fgraph ret_stack, resulting in failing to find the expected entry.
Since the ftrace_regs only exist transiently during function entry/exit, it's
possible for a stackframe to reuse that same address on the stack, which would
result in finding a different entry by mistake.
The diff below restores the existing behaviour and fixes the issue for me.
Could you please fold that into this patch?
On a separate note, looking at how this patch changed arm64's
ftrace_graph_func(), do we need similar changes to arm64's
prepare_ftrace_return() for the old-style mcount based ftrace?
Mark.
---->8----
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index 205937e04ece..329092ce06ba 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -495,7 +495,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
if (bit < 0)
return;
- if (!function_graph_enter_ops(*parent, ip, fregs->fp, parent, gops))
+ if (!function_graph_enter_ops(*parent, ip, fregs->fp, (void *)fregs->fp, gops))
*parent = (unsigned long)&return_to_handler;
ftrace_test_recursion_unlock(bit);
^ permalink raw reply related [flat|nested] 56+ messages in thread* Re: [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering
2024-01-08 14:21 ` Mark Rutland
@ 2024-01-08 15:03 ` Mark Rutland
2024-01-11 13:47 ` Masami Hiramatsu
0 siblings, 1 reply; 56+ messages in thread
From: Mark Rutland @ 2024-01-08 15:03 UTC (permalink / raw)
To: Masami Hiramatsu
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Mon, Jan 08, 2024 at 02:21:03PM +0000, Mark Rutland wrote:
> On Mon, Jan 08, 2024 at 12:25:55PM +0000, Mark Rutland wrote:
> > We also have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR, but since the return address is
> > not on the stack at the point function-entry is intercepted we use the FP as
> > the retp value -- in the absence of tail calls this will be different between a
> > caller and callee.
>
> Ah; I just spotted that this patch changed that in ftrace_graph_func(), which
> is the source of the bug.
>
> As of this patch, we use the address of fregs->lr as the retp value, but the
> unwinder still uses the FP value, and so when unwind_recover_return_address()
> calls ftrace_graph_ret_addr(), the retp value won't match the expected entry on
> the fgraph ret_stack, resulting in failing to find the expected entry.
>
> Since the ftrace_regs only exist transiently during function entry/exit, it's
> possible for a stackframe to reuse that same address on the stack, which would
> result in finding a different entry by mistake.
>
> The diff below restores the existing behaviour and fixes the issue for me.
> Could you please fold that into this patch?
>
> On a separate note, looking at how this patch changed arm64's
> ftrace_graph_func(), do we need similar changes to arm64's
> prepare_ftrace_return() for the old-style mcount based ftrace?
>
> Mark.
>
> ---->8----
> diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
> index 205937e04ece..329092ce06ba 100644
> --- a/arch/arm64/kernel/ftrace.c
> +++ b/arch/arm64/kernel/ftrace.c
> @@ -495,7 +495,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
> if (bit < 0)
> return;
>
> - if (!function_graph_enter_ops(*parent, ip, fregs->fp, parent, gops))
> + if (!function_graph_enter_ops(*parent, ip, fregs->fp, (void *)fregs->fp, gops))
> *parent = (unsigned long)&return_to_handler;
>
> ftrace_test_recursion_unlock(bit);
Thinking some more, this line gets excessively long when we pass the fregs too,
so it's probably worth adding a local variable for fp, i.e. the diff below.
Mark.
---->8----
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index 205937e04ece..d4e142ef4686 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -481,8 +481,9 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs)
{
- unsigned long *parent = &fregs->lr;
struct fgraph_ops *gops = container_of(op, struct fgraph_ops, ops);
+ unsigned long *parent = &fregs->lr;
+ unsigned long fp = fregs->fp;
int bit;
if (unlikely(ftrace_graph_is_dead()))
@@ -495,7 +496,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
if (bit < 0)
return;
- if (!function_graph_enter_ops(*parent, ip, fregs->fp, parent, gops))
+ if (!function_graph_enter_ops(*parent, ip, fp, (void *)fp, gops))
*parent = (unsigned long)&return_to_handler;
ftrace_test_recursion_unlock(bit);
^ permalink raw reply related [flat|nested] 56+ messages in thread* Re: [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering
2024-01-08 15:03 ` Mark Rutland
@ 2024-01-11 13:47 ` Masami Hiramatsu
0 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu @ 2024-01-11 13:47 UTC (permalink / raw)
To: Mark Rutland
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Mon, 8 Jan 2024 15:03:21 +0000
Mark Rutland <mark.rutland@arm.com> wrote:
> On Mon, Jan 08, 2024 at 02:21:03PM +0000, Mark Rutland wrote:
> > On Mon, Jan 08, 2024 at 12:25:55PM +0000, Mark Rutland wrote:
> > > We also have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR, but since the return address is
> > > not on the stack at the point function-entry is intercepted we use the FP as
> > > the retp value -- in the absence of tail calls this will be different between a
> > > caller and callee.
> >
> > Ah; I just spotted that this patch changed that in ftrace_graph_func(), which
> > is the source of the bug.
> >
> > As of this patch, we use the address of fregs->lr as the retp value, but the
> > unwinder still uses the FP value, and so when unwind_recover_return_address()
> > calls ftrace_graph_ret_addr(), the retp value won't match the expected entry on
> > the fgraph ret_stack, resulting in failing to find the expected entry.
> >
> > Since the ftrace_regs only exist transiently during function entry/exit, it's
> > possible for a stackframe to reuse that same address on the stack, which would
> > result in finding a different entry by mistake.
> >
> > The diff below restores the existing behaviour and fixes the issue for me.
> > Could you please fold that into this patch?
> >
> > On a separate note, looking at how this patch changed arm64's
> > ftrace_graph_func(), do we need similar changes to arm64's
> > prepare_ftrace_return() for the old-style mcount based ftrace?
> >
> > Mark.
> >
> > ---->8----
> > diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
> > index 205937e04ece..329092ce06ba 100644
> > --- a/arch/arm64/kernel/ftrace.c
> > +++ b/arch/arm64/kernel/ftrace.c
> > @@ -495,7 +495,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
> > if (bit < 0)
> > return;
> >
> > - if (!function_graph_enter_ops(*parent, ip, fregs->fp, parent, gops))
> > + if (!function_graph_enter_ops(*parent, ip, fregs->fp, (void *)fregs->fp, gops))
> > *parent = (unsigned long)&return_to_handler;
> >
> > ftrace_test_recursion_unlock(bit);
>
> Thinking some more, this line gets excessively long when we pass the fregs too,
> so it's probably worth adding a local variable for fp, i.e. the diff below.
Yeah, that will be better to keep the line short.
Thank you,
>
> Mark.
>
> ---->8----
> diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
> index 205937e04ece..d4e142ef4686 100644
> --- a/arch/arm64/kernel/ftrace.c
> +++ b/arch/arm64/kernel/ftrace.c
> @@ -481,8 +481,9 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
> void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
> struct ftrace_ops *op, struct ftrace_regs *fregs)
> {
> - unsigned long *parent = &fregs->lr;
> struct fgraph_ops *gops = container_of(op, struct fgraph_ops, ops);
> + unsigned long *parent = &fregs->lr;
> + unsigned long fp = fregs->fp;
> int bit;
>
> if (unlikely(ftrace_graph_is_dead()))
> @@ -495,7 +496,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
> if (bit < 0)
> return;
>
> - if (!function_graph_enter_ops(*parent, ip, fregs->fp, parent, gops))
> + if (!function_graph_enter_ops(*parent, ip, fp, (void *)fp, gops))
> *parent = (unsigned long)&return_to_handler;
>
> ftrace_test_recursion_unlock(bit);
>
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 56+ messages in thread
* Re: [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering
2024-01-08 12:25 ` Mark Rutland
2024-01-08 14:21 ` Mark Rutland
@ 2024-01-11 2:15 ` Masami Hiramatsu
2024-01-11 11:01 ` Mark Rutland
1 sibling, 1 reply; 56+ messages in thread
From: Masami Hiramatsu @ 2024-01-11 2:15 UTC (permalink / raw)
To: Mark Rutland
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Peter Zijlstra, Thomas Gleixner,
Guo Ren
Hi Mark,
Thanks for the investigation.
On Mon, 8 Jan 2024 12:25:55 +0000
Mark Rutland <mark.rutland@arm.com> wrote:
> Hi,
>
> There's a bit more of an info-dump below; I'll go try to dump the fgraph shadow
> stack so that we can analyse this in more detail.
>
> On Mon, Jan 08, 2024 at 10:14:36AM +0900, Masami Hiramatsu wrote:
> > On Fri, 5 Jan 2024 17:09:10 +0000
> > Mark Rutland <mark.rutland@arm.com> wrote:
> >
> > > On Mon, Dec 18, 2023 at 10:13:46PM +0900, Masami Hiramatsu (Google) wrote:
> > > > From: Steven Rostedt (VMware) <rostedt@goodmis.org>
> > > >
> > > > Allow for instances to have their own ftrace_ops part of the fgraph_ops
> > > > that makes the funtion_graph tracer filter on the set_ftrace_filter file
> > > > of the instance and not the top instance.
> > > >
> > > > This also change how the function_graph handles multiple instances on the
> > > > shadow stack. Previously we use ARRAY type entries to record which one
> > > > is enabled, and this makes it a bitmap of the fgraph_array's indexes.
> > > > Previous function_graph_enter() expects calling back from
> > > > prepare_ftrace_return() function which is called back only once if it is
> > > > enabled. But this introduces different ftrace_ops for each fgraph
> > > > instance and those are called from ftrace_graph_func() one by one. Thus
> > > > we can not loop on the fgraph_array(), and need to reuse the ret_stack
> > > > pushed by the previous instance. Finding the ret_stack is easy because
> > > > we can check the ret_stack->func. But that is not enough for the self-
> > > > recursive tail-call case. Thus fgraph uses the bitmap entry to find it
> > > > is already set (this means that entry is for previous tail call).
> > > >
> > > > Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> > > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > >
> > > As a heads-up, while testing the topic/fprobe-on-fgraph branch on arm64, I get
> > > a warning which bisets down to this commit:
> >
> > Hmm, so does this happen when enabling function graph tracer?
>
> Yes; I see it during the function_graph boot-time self-test if I also enable
> CONFIG_IRQSOFF_TRACER=y. I can also trigger it regardless of
> CONFIG_IRQSOFF_TRACER if I cat /proc/self/stack with the function_graph tracer
> enabled (note that I hacked the unwinder to continue after failing to recover a
> return address):
>
> | # mount -t tracefs none /sys/kernel/tracing/
> | # echo function_graph > /sys/kernel/tracing/current_tracer
> | # cat /proc/self/stack
> | [ 37.469980] ------------[ cut here ]------------
> | [ 37.471503] WARNING: CPU: 2 PID: 174 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x2d8/0x338
> | [ 37.474381] Modules linked in:
> | [ 37.475501] CPU: 2 PID: 174 Comm: cat Not tainted 6.7.0-rc2-00026-gea1e68a341c2-dirty #15
> | [ 37.478133] Hardware name: linux,dummy-virt (DT)
> | [ 37.479670] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> | [ 37.481923] pc : arch_stack_walk+0x2d8/0x338
> | [ 37.483373] lr : arch_stack_walk+0x1bc/0x338
> | [ 37.484818] sp : ffff8000835f3a90
> | [ 37.485974] x29: ffff8000835f3a90 x28: ffff8000835f3b80 x27: ffff8000835f3b38
> | [ 37.488405] x26: ffff000004341e00 x25: ffff8000835f4000 x24: ffff80008002df18
> | [ 37.490842] x23: ffff80008002df18 x22: ffff8000835f3b60 x21: ffff80008015d240
> | [ 37.493269] x20: ffff8000835f3b50 x19: ffff8000835f3b40 x18: 0000000000000000
> | [ 37.495704] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
> | [ 37.498144] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
> | [ 37.500579] x11: ffff800082b4d920 x10: ffff8000835f3a70 x9 : ffff8000800e55a0
> | [ 37.503021] x8 : ffff80008002df18 x7 : ffff000004341e00 x6 : 00000000ffffffff
> | [ 37.505452] x5 : 0000000000000000 x4 : ffff8000835f3e48 x3 : ffff8000835f3b80
> | [ 37.507888] x2 : ffff80008002df18 x1 : ffff000007f7b000 x0 : ffff80008002df18
> | [ 37.510319] Call trace:
> | [ 37.511202] arch_stack_walk+0x2d8/0x338
> | [ 37.512541] stack_trace_save_tsk+0x90/0x110
> | [ 37.514012] return_to_handler+0x0/0x48
> | [ 37.515336] return_to_handler+0x0/0x48
> | [ 37.516657] return_to_handler+0x0/0x48
> | [ 37.517985] return_to_handler+0x0/0x48
> | [ 37.519305] return_to_handler+0x0/0x48
> | [ 37.520623] return_to_handler+0x0/0x48
> | [ 37.521957] return_to_handler+0x0/0x48
> | [ 37.523272] return_to_handler+0x0/0x48
> | [ 37.524595] return_to_handler+0x0/0x48
> | [ 37.525931] return_to_handler+0x0/0x48
> | [ 37.527254] return_to_handler+0x0/0x48
> | [ 37.528564] el0t_64_sync_handler+0x120/0x130
> | [ 37.530046] el0t_64_sync+0x190/0x198
> | [ 37.531310] ---[ end trace 0000000000000000 ]---
> | [<0>] ftrace_stub_graph+0x8/0x8
> | [<0>] ftrace_stub_graph+0x8/0x8
> | [<0>] ftrace_stub_graph+0x8/0x8
> | [<0>] ftrace_stub_graph+0x8/0x8
> | [<0>] ftrace_stub_graph+0x8/0x8
> | [<0>] ftrace_stub_graph+0x8/0x8
> | [<0>] ftrace_stub_graph+0x8/0x8
> | [<0>] ftrace_stub_graph+0x8/0x8
> | [<0>] ftrace_stub_graph+0x8/0x8
> | [<0>] ftrace_stub_graph+0x8/0x8
> | [<0>] ftrace_stub_graph+0x8/0x8
> | [<0>] el0t_64_sync_handler+0x120/0x130
> | [<0>] el0t_64_sync+0x190/0x198
Hmm, I haven't see this mode.
>
> One interesting thing there is that there are two distinct failure modes: the
> unwind for the WARNING gives return_to_handler instead of the original return
> address, and the unwind returned from /proc/self/stack gives ftrace_stub_graph
> rather than the original return address.
>
> > >
> > > | Testing tracer function_graph:
> > > | ------------[ cut here ]------------
> > > | WARNING: CPU: 2 PID: 0 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x3c0/0x3d8
> > > | Modules linked in:
> > > | CPU: 2 PID: 0 Comm: swapper/2 Not tainted 6.7.0-rc2-00026-gea1e68a341c2 #12
> > > | Hardware name: linux,dummy-virt (DT)
> > > | pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > > | pc : arch_stack_walk+0x3c0/0x3d8
> > > | lr : arch_stack_walk+0x260/0x3d8
> > > | sp : ffff80008318be00
> > > | x29: ffff80008318be00 x28: ffff000003c0ae80 x27: 0000000000000000
> > > | x26: 0000000000000000 x25: ffff000003c0ae80 x24: 0000000000000000
> > > | x23: ffff8000800234c8 x22: ffff80008002dc30 x21: ffff800080035d10
> > > | x20: ffff80008318bee8 x19: ffff800080023460 x18: ffff800083453c68
> > > | x17: 0000000000000000 x16: ffff800083188000 x15: 000000008ccc5058
> > > | x14: 0000000000000004 x13: ffff800082b8c4f0 x12: 0000000000000000
> > > | x11: ffff800081fba9b0 x10: ffff80008318bff0 x9 : ffff800080010798
> > > | x8 : ffff80008002dc30 x7 : ffff000003c0ae80 x6 : 00000000ffffffff
> > > | x5 : 0000000000000000 x4 : ffff8000832a3c18 x3 : ffff80008318bff0
> > > | x2 : ffff80008002dc30 x1 : ffff80008002dc30 x0 : ffff80008002dc30
> > > | Call trace:
> > > | arch_stack_walk+0x3c0/0x3d8
> > > | return_address+0x40/0x80
> > > | trace_hardirqs_on+0x8c/0x198
> > > | __do_softirq+0xe8/0x440
> > > | ---[ end trace 0000000000000000 ]---
>
> With the smae hack to continue after failing to recover a return address, the
> failure in the selftest looks like:
>
> | ------------[ cut here ]------------
> | WARNING: CPU: 7 PID: 0 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x2d8/0x338
> | Modules linked in:
> | CPU: 7 PID: 0 Comm: swapper/7 Not tainted 6.7.0-rc2-00026-gea1e68a341c2-dirty #14
> | Hardware name: linux,dummy-virt (DT)
> | pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> | pc : arch_stack_walk+0x2d8/0x338
> | lr : arch_stack_walk+0x1bc/0x338
> | sp : ffff8000830c3e20
> | x29: ffff8000830c3e20 x28: ffff8000830c3ff0 x27: ffff8000830c3ec8
> | x26: ffff0000037e0000 x25: ffff8000830c4000 x24: ffff80008002e080
> | x23: ffff80008002e080 x22: ffff8000830c3ee8 x21: ffff800080023418
> | x20: ffff8000830c3f50 x19: ffff8000830c3f40 x18: ffffffffffffffff
> | x17: 0000000000000000 x16: ffff8000830c0000 x15: 0000000000000000
> | x14: 0000000000000002 x13: ffff8000800360f8 x12: ffff800080028330
> | x11: ffff800081f4a978 x10: ffff8000830c3ff0 x9 : ffff800080010798
> | x8 : ffff80008002e080 x7 : ffff0000037e0000 x6 : 00000000ffffffff
> | x5 : 0000000000000000 x4 : ffff8000831dbc18 x3 : ffff8000830c3ff0
> | x2 : ffff80008002e080 x1 : ffff0000040a3000 x0 : ffff80008002e080
> | Call trace:
> | arch_stack_walk+0x2d8/0x338
> | return_address+0x40/0x80
> | trace_hardirqs_on+0x8c/0x198
> | __do_softirq+0xe8/0x43c
> | return_to_handler+0x0/0x48
> | return_to_handler+0x0/0x48
> | do_softirq_own_stack+0x24/0x38
> | return_to_handler+0x0/0x48
> | el1_interrupt+0x38/0x68
> | el1h_64_irq_handler+0x18/0x28
> | el1h_64_irq+0x64/0x68
> | default_idle_call+0x70/0x178
> | do_idle+0x228/0x290
> | cpu_startup_entry+0x40/0x50
> | secondary_start_kernel+0x138/0x160
> | __secondary_switched+0xb8/0xc0
> | ---[ end trace 0000000000000000 ]---
I usually see this and reproduced. Here, I also add a dump of shadow stack.
It seems that the unwinder goes to the bottome of the shadow stack.
/sys/kernel/tracing # echo function_graph > current_tracer
[ 89.887750] ------------[ cut here ]------------
[ 89.889864] Dump: return_to_handler = ffffb45fc6a2f1e8
[ 89.891833] ret_stack[20]: 20406 0x20406 type = 1, index = 6
[ 89.896118] ret_stack[19]: ffff800080003be8 0xffff800080003be8 type = 2, index = 1000
[ 89.896233] ret_stack[18]: ffff800080003c20 0xffff800080003c20 type = 3, index = 32
[ 89.896362] ret_stack[17]: 0 0x0 type = 0, index = 0
[ 89.896425] ret_stack[16]: 14edac7710 0x14edac7710 type = 1, index = 784
[ 89.896635] ret_stack[15]: ffffb45fc6a1610c call_break_hook+0x4/0x108 type = 0, index = 268
[ 89.897882] ret_stack[14]: ffffb45fc6a162fc brk_handler+0x24/0x70 type = 0, index = 764
[ 89.898139] ret_stack[13]: 20406 0x20406 type = 1, index = 6
[ 89.898337] ret_stack[12]: ffff800080003c08 0xffff800080003c08 type = 3, index = 8
[ 89.898554] ret_stack[11]: ffff800080003c40 0xffff800080003c40 type = 3, index = 64
[ 89.898645] ret_stack[10]: 0 0x0 type = 0, index = 0
[ 89.898832] ret_stack[9]: 14eda8f920 0x14eda8f920 type = 2, index = 288
[ 89.899069] ret_stack[8]: ffffb45fc6a162dc brk_handler+0x4/0x70 type = 0, index = 732
[ 89.899230] ret_stack[7]: ffffb45fc6a36c24 do_debug_exception+0x74/0x108 type = 3, index = 36
[ 89.899385] ret_stack[6]: 20406 0x20406 type = 1, index = 6
[ 89.899456] ret_stack[5]: ffff800080003fb8 0xffff800080003fb8 type = 3, index = 952
[ 89.899518] ret_stack[4]: ffff800080003ff0 0xffff800080003ff0 type = 3, index = 1008
[ 89.899578] ret_stack[3]: ffff62a80534d21c 0xffff62a80534d21c type = 0, index = 540
[ 89.899637] ret_stack[2]: 14ed8ed2e0 0x14ed8ed2e0 type = 0, index = 736
[ 89.899695] ret_stack[1]: ffffb45fc6a1069c __do_softirq+0x4/0x4f0 type = 1, index = 668
[ 89.899986] ret_stack[15]: ffff62a80534d070
[ 89.900221] func: call_break_hook, return:brk_handler
[ 89.901025] ret_stack[8]: ffff62a80534d038
[ 89.901223] func: brk_handler, return:do_debug_exception
[ 89.901450] ret_stack[1]: ffff62a80534d000
[ 89.901501] func: __do_softirq, return:____do_softirq
[ 89.901693] ret_stack[1]: 0
[ 90.015738] WARNING: CPU: 0 PID: 0 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x2d8/0x380
[ 90.022314] Modules linked in:
[ 90.032375] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G N 6.7.0-rc8-00036-g3897e34e8ae2-dirty #79
[ 90.038797] Hardware name: linux,dummy-virt (DT)
[ 90.044170] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 90.048879] pc : arch_stack_walk+0x2d8/0x380
[ 90.052222] lr : arch_stack_walk+0x248/0x380
[ 90.055635] sp : ffff800080003e20
[ 90.058147] x29: ffff800080003e20 x28: ffffb45fc91993c0 x27: 0000000000000000
[ 90.063705] x26: 0000000000000000 x25: 0000000000000000 x24: ffffb45fc918fb40
[ 90.068946] x23: ffffb45fc6a247b8 x22: ffffb45fc6a2f1e8 x21: ffffb45fc6a35b30
[ 90.074894] x20: ffff800080003ef8 x19: ffffb45fc6a24750 x18: 0000000000000000
[ 90.078796] x17: 0000000000000000 x16: ffff800080000000 x15: 0000ffffff477588
[ 90.084310] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
[ 90.088898] x11: ffffb45fc924ca08 x10: ffff62a8040341c0 x9 : ffffb45fc6a10760
[ 90.094430] x8 : ffffb45fc6a2f1e8 x7 : ffffb45fc91993c0 x6 : ffff62a80534d000
[ 90.099829] x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff800080003ff0
[ 90.104442] x2 : ffffb45fc6a2f1e8 x1 : ffffb45fc6a2f1e8 x0 : ffffb45fc6a2f1e8
[ 90.111735] Call trace:
[ 90.114923] arch_stack_walk+0x2d8/0x380
[ 90.118820] return_address+0x40/0x80
[ 90.122057] trace_hardirqs_on+0xa0/0x100
[ 90.125001] __do_softirq+0xec/0x4f0
[ 90.130907] irq event stamp: 102709
[ 90.134223] hardirqs last enabled at (102707): [<ffffb45fc7af51d8>] default_idle_call+0xa0/0x160
[ 90.140612] hardirqs last disabled at (102708): [<ffffb45fc7af26ec>] el1_interrupt+0x24/0x68
[ 90.145877] softirqs last enabled at (102702): [<ffffb45fc6a10b40>] __do_softirq+0x4a8/0x4f0
[ 90.148952] softirqs last disabled at (102709): [<ffffb45fc6a2f1e8>] return_to_handler+0x0/0x50
[ 90.152834] ---[ end trace 0000000000000000 ]---
>
> The portion of the trace with:
>
> __do_softirq+0xe8/0x43c
> return_to_handler+0x0/0x48
> return_to_handler+0x0/0x48
> do_softirq_own_stack+0x24/0x38
>
> ... should be something like:
>
> __do_softirq
> ____do_softirq
> call_on_irq_stack // asm trampoline, not traceable
> do_softirq_own_stack
>
> The generated assembly for do_softirq_own_stack(), ____do_softirq(), and
> __do_softirq() is as I'd expect with no tail calls, so I can't see an obvious
> reason the return address cannot be recovered correctly.
My question is that even if unwinder fails, the program runs normally.
Isn't it a real stack entry?
>
> > > That's a warning in arm64's unwind_recover_return_address() function, which
> > > fires when ftrace_graph_ret_addr() finds return_to_handler:
> > >
> > > if (state->task->ret_stack &&
> > > (state->pc == (unsigned long)return_to_handler)) {
> > > unsigned long orig_pc;
> > > orig_pc = ftrace_graph_ret_addr(state->task, NULL, state->pc,
> > > (void *)state->fp);
> > > if (WARN_ON_ONCE(state->pc == orig_pc))
> > > return -EINVAL;
> > > state->pc = orig_pc;
> > > }
> > >
> > > The rationale there is that since tail calls are (currently) disabled on arm64,
> > > the only reason for ftrace_graph_ret_addr() to return return_to_handler is when
> > > it fails to find the original return address.
> >
> > Yes. what about FP check?
>
> Do you mean HAVE_FUNCTION_GRAPH_FP_TEST?
>
> That is enabled, and there are warnings from ftrace_pop_return_trace(), so I
> believe push/pop is balanced.
OK.
>
> We also have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR, but since the return address is
> not on the stack at the point function-entry is intercepted we use the FP as
> the retp value -- in the absence of tail calls this will be different between a
> caller and callee.
>
> > > Does this change make it legitimate for ftrace_graph_ret_addr() to return
> > > return_to_handler in other cases, or is that a bug?
> >
> > It should be a bug to be fixed.
>
> Cool; thanks for confirming!
>
> > > Either way, we'll need *some* way to recover the original return addresss...
> >
> > At least it needs to dump the shadow stack so that we can analyze what
> > happened.
>
> Sounds like a plan; as above I'll have a go at putting that together and will
> dump the results here.
Yeah, please try below patch.
Thanks,
---
arch/arm64/kernel/stacktrace.c | 10 +++++++++-
include/linux/ftrace.h | 2 ++
kernel/trace/fgraph.c | 24 ++++++++++++++++++++++++
3 files changed, 35 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 17f66a74c745..0eaba1bad599 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -81,8 +81,16 @@ unwind_recover_return_address(struct unwind_state *state)
unsigned long orig_pc;
orig_pc = ftrace_graph_ret_addr(state->task, NULL, state->pc,
(void *)state->fp);
- if (WARN_ON_ONCE(state->pc == orig_pc))
+ if (WARN_ON_ONCE(state->pc == orig_pc)) {
+ static bool dumped;
+
+ if (!dumped) {
+ pr_info("Dump: return_to_handler = %lx\n", (unsigned long)return_to_handler);
+ dumped = true;
+ fgraph_dump_ret_stack(state->task);
+ }
return -EINVAL;
+ }
state->pc = orig_pc;
}
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index ad28daa507f7..cfb79977fdec 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1258,6 +1258,8 @@ static inline void unpause_graph_tracing(void)
{
atomic_dec(¤t->tracing_graph_pause);
}
+
+void fgraph_dump_ret_stack(struct task_struct *t);
#else /* !CONFIG_FUNCTION_GRAPH_TRACER */
#define __notrace_funcgraph
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 0f11f80bdd6c..5dd560fbacce 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -437,6 +437,30 @@ get_ret_stack(struct task_struct *t, int offset, int *index)
return RET_STACK(t, offset);
}
+void fgraph_dump_ret_stack(struct task_struct *t)
+{
+ struct ftrace_ret_stack *ret_stack;
+ unsigned long val;
+ int i, offset, next;
+
+ for (i = t->curr_ret_stack - 1; i > 0; i--) {
+ val = get_fgraph_entry(t, i);
+ pr_err(" ret_stack[%d]: %lx %pS type = %d, index = %d\n",
+ i, val, (void *)val, __get_type(val), __get_index(val));
+ }
+ offset = t->curr_ret_stack;
+ do {
+ ret_stack = get_ret_stack(t, offset, &next);
+ pr_err("ret_stack[%d]: %lx\n",
+ next + 1, (unsigned long)ret_stack);
+ if (ret_stack) {
+ pr_err("\tfunc: %ps, return:%ps\n",
+ (void *)ret_stack->func, (void *)ret_stack->ret);
+ }
+ offset = next;
+ } while (ret_stack);
+}
+
/* Both enabled by default (can be cleared by function_graph tracer flags */
static bool fgraph_sleep_time = true;
--
2.34.1
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply related [flat|nested] 56+ messages in thread* Re: [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering
2024-01-11 2:15 ` Masami Hiramatsu
@ 2024-01-11 11:01 ` Mark Rutland
2024-01-11 13:45 ` Masami Hiramatsu
0 siblings, 1 reply; 56+ messages in thread
From: Mark Rutland @ 2024-01-11 11:01 UTC (permalink / raw)
To: Masami Hiramatsu
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Thu, Jan 11, 2024 at 11:15:33AM +0900, Masami Hiramatsu wrote:
> Hi Mark,
>
> Thanks for the investigation.
Hi!
As a heads-up, I already figured out the problem and sent a fixup at:
https://lore.kernel.org/lkml/ZZwEz8HsTa2IZE3L@FVFF77S0Q05N/
... and a more refined fix at:
https://lore.kernel.org/lkml/ZZwOubTSbB_FucVz@FVFF77S0Q05N/
The gist was that before this patch, arm64 used the FP as the 'retp' value, but
this patch changed that to the address of fregs->lr. This meant that the fgraph
ret_stack contained all of the correct return addresses, but when the unwinder
called ftrace_graph_ret_addr() with FP as the 'retp' value, it failed to match
any entry in the ret_stack.
Since the fregs only exist transiently at function entry and exit, I'd prefer
that we still use the FP as the 'retp' value, which is what I proposed in the
fixups above.
Thanks,
Mark.
> On Mon, 8 Jan 2024 12:25:55 +0000
> Mark Rutland <mark.rutland@arm.com> wrote:
>
> > Hi,
> >
> > There's a bit more of an info-dump below; I'll go try to dump the fgraph shadow
> > stack so that we can analyse this in more detail.
> >
> > On Mon, Jan 08, 2024 at 10:14:36AM +0900, Masami Hiramatsu wrote:
> > > On Fri, 5 Jan 2024 17:09:10 +0000
> > > Mark Rutland <mark.rutland@arm.com> wrote:
> > >
> > > > On Mon, Dec 18, 2023 at 10:13:46PM +0900, Masami Hiramatsu (Google) wrote:
> > > > > From: Steven Rostedt (VMware) <rostedt@goodmis.org>
> > > > >
> > > > > Allow for instances to have their own ftrace_ops part of the fgraph_ops
> > > > > that makes the funtion_graph tracer filter on the set_ftrace_filter file
> > > > > of the instance and not the top instance.
> > > > >
> > > > > This also change how the function_graph handles multiple instances on the
> > > > > shadow stack. Previously we use ARRAY type entries to record which one
> > > > > is enabled, and this makes it a bitmap of the fgraph_array's indexes.
> > > > > Previous function_graph_enter() expects calling back from
> > > > > prepare_ftrace_return() function which is called back only once if it is
> > > > > enabled. But this introduces different ftrace_ops for each fgraph
> > > > > instance and those are called from ftrace_graph_func() one by one. Thus
> > > > > we can not loop on the fgraph_array(), and need to reuse the ret_stack
> > > > > pushed by the previous instance. Finding the ret_stack is easy because
> > > > > we can check the ret_stack->func. But that is not enough for the self-
> > > > > recursive tail-call case. Thus fgraph uses the bitmap entry to find it
> > > > > is already set (this means that entry is for previous tail call).
> > > > >
> > > > > Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> > > > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > > >
> > > > As a heads-up, while testing the topic/fprobe-on-fgraph branch on arm64, I get
> > > > a warning which bisets down to this commit:
> > >
> > > Hmm, so does this happen when enabling function graph tracer?
> >
> > Yes; I see it during the function_graph boot-time self-test if I also enable
> > CONFIG_IRQSOFF_TRACER=y. I can also trigger it regardless of
> > CONFIG_IRQSOFF_TRACER if I cat /proc/self/stack with the function_graph tracer
> > enabled (note that I hacked the unwinder to continue after failing to recover a
> > return address):
> >
> > | # mount -t tracefs none /sys/kernel/tracing/
> > | # echo function_graph > /sys/kernel/tracing/current_tracer
> > | # cat /proc/self/stack
> > | [ 37.469980] ------------[ cut here ]------------
> > | [ 37.471503] WARNING: CPU: 2 PID: 174 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x2d8/0x338
> > | [ 37.474381] Modules linked in:
> > | [ 37.475501] CPU: 2 PID: 174 Comm: cat Not tainted 6.7.0-rc2-00026-gea1e68a341c2-dirty #15
> > | [ 37.478133] Hardware name: linux,dummy-virt (DT)
> > | [ 37.479670] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > | [ 37.481923] pc : arch_stack_walk+0x2d8/0x338
> > | [ 37.483373] lr : arch_stack_walk+0x1bc/0x338
> > | [ 37.484818] sp : ffff8000835f3a90
> > | [ 37.485974] x29: ffff8000835f3a90 x28: ffff8000835f3b80 x27: ffff8000835f3b38
> > | [ 37.488405] x26: ffff000004341e00 x25: ffff8000835f4000 x24: ffff80008002df18
> > | [ 37.490842] x23: ffff80008002df18 x22: ffff8000835f3b60 x21: ffff80008015d240
> > | [ 37.493269] x20: ffff8000835f3b50 x19: ffff8000835f3b40 x18: 0000000000000000
> > | [ 37.495704] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
> > | [ 37.498144] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
> > | [ 37.500579] x11: ffff800082b4d920 x10: ffff8000835f3a70 x9 : ffff8000800e55a0
> > | [ 37.503021] x8 : ffff80008002df18 x7 : ffff000004341e00 x6 : 00000000ffffffff
> > | [ 37.505452] x5 : 0000000000000000 x4 : ffff8000835f3e48 x3 : ffff8000835f3b80
> > | [ 37.507888] x2 : ffff80008002df18 x1 : ffff000007f7b000 x0 : ffff80008002df18
> > | [ 37.510319] Call trace:
> > | [ 37.511202] arch_stack_walk+0x2d8/0x338
> > | [ 37.512541] stack_trace_save_tsk+0x90/0x110
> > | [ 37.514012] return_to_handler+0x0/0x48
> > | [ 37.515336] return_to_handler+0x0/0x48
> > | [ 37.516657] return_to_handler+0x0/0x48
> > | [ 37.517985] return_to_handler+0x0/0x48
> > | [ 37.519305] return_to_handler+0x0/0x48
> > | [ 37.520623] return_to_handler+0x0/0x48
> > | [ 37.521957] return_to_handler+0x0/0x48
> > | [ 37.523272] return_to_handler+0x0/0x48
> > | [ 37.524595] return_to_handler+0x0/0x48
> > | [ 37.525931] return_to_handler+0x0/0x48
> > | [ 37.527254] return_to_handler+0x0/0x48
> > | [ 37.528564] el0t_64_sync_handler+0x120/0x130
> > | [ 37.530046] el0t_64_sync+0x190/0x198
> > | [ 37.531310] ---[ end trace 0000000000000000 ]---
> > | [<0>] ftrace_stub_graph+0x8/0x8
> > | [<0>] ftrace_stub_graph+0x8/0x8
> > | [<0>] ftrace_stub_graph+0x8/0x8
> > | [<0>] ftrace_stub_graph+0x8/0x8
> > | [<0>] ftrace_stub_graph+0x8/0x8
> > | [<0>] ftrace_stub_graph+0x8/0x8
> > | [<0>] ftrace_stub_graph+0x8/0x8
> > | [<0>] ftrace_stub_graph+0x8/0x8
> > | [<0>] ftrace_stub_graph+0x8/0x8
> > | [<0>] ftrace_stub_graph+0x8/0x8
> > | [<0>] ftrace_stub_graph+0x8/0x8
> > | [<0>] el0t_64_sync_handler+0x120/0x130
> > | [<0>] el0t_64_sync+0x190/0x198
>
> Hmm, I haven't see this mode.
>
> >
> > One interesting thing there is that there are two distinct failure modes: the
> > unwind for the WARNING gives return_to_handler instead of the original return
> > address, and the unwind returned from /proc/self/stack gives ftrace_stub_graph
> > rather than the original return address.
> >
> > > >
> > > > | Testing tracer function_graph:
> > > > | ------------[ cut here ]------------
> > > > | WARNING: CPU: 2 PID: 0 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x3c0/0x3d8
> > > > | Modules linked in:
> > > > | CPU: 2 PID: 0 Comm: swapper/2 Not tainted 6.7.0-rc2-00026-gea1e68a341c2 #12
> > > > | Hardware name: linux,dummy-virt (DT)
> > > > | pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > > > | pc : arch_stack_walk+0x3c0/0x3d8
> > > > | lr : arch_stack_walk+0x260/0x3d8
> > > > | sp : ffff80008318be00
> > > > | x29: ffff80008318be00 x28: ffff000003c0ae80 x27: 0000000000000000
> > > > | x26: 0000000000000000 x25: ffff000003c0ae80 x24: 0000000000000000
> > > > | x23: ffff8000800234c8 x22: ffff80008002dc30 x21: ffff800080035d10
> > > > | x20: ffff80008318bee8 x19: ffff800080023460 x18: ffff800083453c68
> > > > | x17: 0000000000000000 x16: ffff800083188000 x15: 000000008ccc5058
> > > > | x14: 0000000000000004 x13: ffff800082b8c4f0 x12: 0000000000000000
> > > > | x11: ffff800081fba9b0 x10: ffff80008318bff0 x9 : ffff800080010798
> > > > | x8 : ffff80008002dc30 x7 : ffff000003c0ae80 x6 : 00000000ffffffff
> > > > | x5 : 0000000000000000 x4 : ffff8000832a3c18 x3 : ffff80008318bff0
> > > > | x2 : ffff80008002dc30 x1 : ffff80008002dc30 x0 : ffff80008002dc30
> > > > | Call trace:
> > > > | arch_stack_walk+0x3c0/0x3d8
> > > > | return_address+0x40/0x80
> > > > | trace_hardirqs_on+0x8c/0x198
> > > > | __do_softirq+0xe8/0x440
> > > > | ---[ end trace 0000000000000000 ]---
> >
> > With the smae hack to continue after failing to recover a return address, the
> > failure in the selftest looks like:
> >
> > | ------------[ cut here ]------------
> > | WARNING: CPU: 7 PID: 0 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x2d8/0x338
> > | Modules linked in:
> > | CPU: 7 PID: 0 Comm: swapper/7 Not tainted 6.7.0-rc2-00026-gea1e68a341c2-dirty #14
> > | Hardware name: linux,dummy-virt (DT)
> > | pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > | pc : arch_stack_walk+0x2d8/0x338
> > | lr : arch_stack_walk+0x1bc/0x338
> > | sp : ffff8000830c3e20
> > | x29: ffff8000830c3e20 x28: ffff8000830c3ff0 x27: ffff8000830c3ec8
> > | x26: ffff0000037e0000 x25: ffff8000830c4000 x24: ffff80008002e080
> > | x23: ffff80008002e080 x22: ffff8000830c3ee8 x21: ffff800080023418
> > | x20: ffff8000830c3f50 x19: ffff8000830c3f40 x18: ffffffffffffffff
> > | x17: 0000000000000000 x16: ffff8000830c0000 x15: 0000000000000000
> > | x14: 0000000000000002 x13: ffff8000800360f8 x12: ffff800080028330
> > | x11: ffff800081f4a978 x10: ffff8000830c3ff0 x9 : ffff800080010798
> > | x8 : ffff80008002e080 x7 : ffff0000037e0000 x6 : 00000000ffffffff
> > | x5 : 0000000000000000 x4 : ffff8000831dbc18 x3 : ffff8000830c3ff0
> > | x2 : ffff80008002e080 x1 : ffff0000040a3000 x0 : ffff80008002e080
> > | Call trace:
> > | arch_stack_walk+0x2d8/0x338
> > | return_address+0x40/0x80
> > | trace_hardirqs_on+0x8c/0x198
> > | __do_softirq+0xe8/0x43c
> > | return_to_handler+0x0/0x48
> > | return_to_handler+0x0/0x48
> > | do_softirq_own_stack+0x24/0x38
> > | return_to_handler+0x0/0x48
> > | el1_interrupt+0x38/0x68
> > | el1h_64_irq_handler+0x18/0x28
> > | el1h_64_irq+0x64/0x68
> > | default_idle_call+0x70/0x178
> > | do_idle+0x228/0x290
> > | cpu_startup_entry+0x40/0x50
> > | secondary_start_kernel+0x138/0x160
> > | __secondary_switched+0xb8/0xc0
> > | ---[ end trace 0000000000000000 ]---
>
> I usually see this and reproduced. Here, I also add a dump of shadow stack.
> It seems that the unwinder goes to the bottome of the shadow stack.
>
> /sys/kernel/tracing # echo function_graph > current_tracer
> [ 89.887750] ------------[ cut here ]------------
> [ 89.889864] Dump: return_to_handler = ffffb45fc6a2f1e8
> [ 89.891833] ret_stack[20]: 20406 0x20406 type = 1, index = 6
> [ 89.896118] ret_stack[19]: ffff800080003be8 0xffff800080003be8 type = 2, index = 1000
> [ 89.896233] ret_stack[18]: ffff800080003c20 0xffff800080003c20 type = 3, index = 32
> [ 89.896362] ret_stack[17]: 0 0x0 type = 0, index = 0
> [ 89.896425] ret_stack[16]: 14edac7710 0x14edac7710 type = 1, index = 784
> [ 89.896635] ret_stack[15]: ffffb45fc6a1610c call_break_hook+0x4/0x108 type = 0, index = 268
> [ 89.897882] ret_stack[14]: ffffb45fc6a162fc brk_handler+0x24/0x70 type = 0, index = 764
> [ 89.898139] ret_stack[13]: 20406 0x20406 type = 1, index = 6
> [ 89.898337] ret_stack[12]: ffff800080003c08 0xffff800080003c08 type = 3, index = 8
> [ 89.898554] ret_stack[11]: ffff800080003c40 0xffff800080003c40 type = 3, index = 64
> [ 89.898645] ret_stack[10]: 0 0x0 type = 0, index = 0
> [ 89.898832] ret_stack[9]: 14eda8f920 0x14eda8f920 type = 2, index = 288
> [ 89.899069] ret_stack[8]: ffffb45fc6a162dc brk_handler+0x4/0x70 type = 0, index = 732
> [ 89.899230] ret_stack[7]: ffffb45fc6a36c24 do_debug_exception+0x74/0x108 type = 3, index = 36
> [ 89.899385] ret_stack[6]: 20406 0x20406 type = 1, index = 6
> [ 89.899456] ret_stack[5]: ffff800080003fb8 0xffff800080003fb8 type = 3, index = 952
> [ 89.899518] ret_stack[4]: ffff800080003ff0 0xffff800080003ff0 type = 3, index = 1008
> [ 89.899578] ret_stack[3]: ffff62a80534d21c 0xffff62a80534d21c type = 0, index = 540
> [ 89.899637] ret_stack[2]: 14ed8ed2e0 0x14ed8ed2e0 type = 0, index = 736
> [ 89.899695] ret_stack[1]: ffffb45fc6a1069c __do_softirq+0x4/0x4f0 type = 1, index = 668
> [ 89.899986] ret_stack[15]: ffff62a80534d070
> [ 89.900221] func: call_break_hook, return:brk_handler
> [ 89.901025] ret_stack[8]: ffff62a80534d038
> [ 89.901223] func: brk_handler, return:do_debug_exception
> [ 89.901450] ret_stack[1]: ffff62a80534d000
> [ 89.901501] func: __do_softirq, return:____do_softirq
> [ 89.901693] ret_stack[1]: 0
> [ 90.015738] WARNING: CPU: 0 PID: 0 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x2d8/0x380
> [ 90.022314] Modules linked in:
> [ 90.032375] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G N 6.7.0-rc8-00036-g3897e34e8ae2-dirty #79
> [ 90.038797] Hardware name: linux,dummy-virt (DT)
> [ 90.044170] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [ 90.048879] pc : arch_stack_walk+0x2d8/0x380
> [ 90.052222] lr : arch_stack_walk+0x248/0x380
> [ 90.055635] sp : ffff800080003e20
> [ 90.058147] x29: ffff800080003e20 x28: ffffb45fc91993c0 x27: 0000000000000000
> [ 90.063705] x26: 0000000000000000 x25: 0000000000000000 x24: ffffb45fc918fb40
> [ 90.068946] x23: ffffb45fc6a247b8 x22: ffffb45fc6a2f1e8 x21: ffffb45fc6a35b30
> [ 90.074894] x20: ffff800080003ef8 x19: ffffb45fc6a24750 x18: 0000000000000000
> [ 90.078796] x17: 0000000000000000 x16: ffff800080000000 x15: 0000ffffff477588
> [ 90.084310] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
> [ 90.088898] x11: ffffb45fc924ca08 x10: ffff62a8040341c0 x9 : ffffb45fc6a10760
> [ 90.094430] x8 : ffffb45fc6a2f1e8 x7 : ffffb45fc91993c0 x6 : ffff62a80534d000
> [ 90.099829] x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff800080003ff0
> [ 90.104442] x2 : ffffb45fc6a2f1e8 x1 : ffffb45fc6a2f1e8 x0 : ffffb45fc6a2f1e8
> [ 90.111735] Call trace:
> [ 90.114923] arch_stack_walk+0x2d8/0x380
> [ 90.118820] return_address+0x40/0x80
> [ 90.122057] trace_hardirqs_on+0xa0/0x100
> [ 90.125001] __do_softirq+0xec/0x4f0
> [ 90.130907] irq event stamp: 102709
> [ 90.134223] hardirqs last enabled at (102707): [<ffffb45fc7af51d8>] default_idle_call+0xa0/0x160
> [ 90.140612] hardirqs last disabled at (102708): [<ffffb45fc7af26ec>] el1_interrupt+0x24/0x68
> [ 90.145877] softirqs last enabled at (102702): [<ffffb45fc6a10b40>] __do_softirq+0x4a8/0x4f0
> [ 90.148952] softirqs last disabled at (102709): [<ffffb45fc6a2f1e8>] return_to_handler+0x0/0x50
> [ 90.152834] ---[ end trace 0000000000000000 ]---
>
>
> >
> > The portion of the trace with:
> >
> > __do_softirq+0xe8/0x43c
> > return_to_handler+0x0/0x48
> > return_to_handler+0x0/0x48
> > do_softirq_own_stack+0x24/0x38
> >
> > ... should be something like:
> >
> > __do_softirq
> > ____do_softirq
> > call_on_irq_stack // asm trampoline, not traceable
> > do_softirq_own_stack
> >
> > The generated assembly for do_softirq_own_stack(), ____do_softirq(), and
> > __do_softirq() is as I'd expect with no tail calls, so I can't see an obvious
> > reason the return address cannot be recovered correctly.
>
> My question is that even if unwinder fails, the program runs normally.
> Isn't it a real stack entry?
>
> >
> > > > That's a warning in arm64's unwind_recover_return_address() function, which
> > > > fires when ftrace_graph_ret_addr() finds return_to_handler:
> > > >
> > > > if (state->task->ret_stack &&
> > > > (state->pc == (unsigned long)return_to_handler)) {
> > > > unsigned long orig_pc;
> > > > orig_pc = ftrace_graph_ret_addr(state->task, NULL, state->pc,
> > > > (void *)state->fp);
> > > > if (WARN_ON_ONCE(state->pc == orig_pc))
> > > > return -EINVAL;
> > > > state->pc = orig_pc;
> > > > }
> > > >
> > > > The rationale there is that since tail calls are (currently) disabled on arm64,
> > > > the only reason for ftrace_graph_ret_addr() to return return_to_handler is when
> > > > it fails to find the original return address.
> > >
> > > Yes. what about FP check?
> >
> > Do you mean HAVE_FUNCTION_GRAPH_FP_TEST?
> >
> > That is enabled, and there are warnings from ftrace_pop_return_trace(), so I
> > believe push/pop is balanced.
>
> OK.
>
> >
> > We also have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR, but since the return address is
> > not on the stack at the point function-entry is intercepted we use the FP as
> > the retp value -- in the absence of tail calls this will be different between a
> > caller and callee.
> >
> > > > Does this change make it legitimate for ftrace_graph_ret_addr() to return
> > > > return_to_handler in other cases, or is that a bug?
> > >
> > > It should be a bug to be fixed.
> >
> > Cool; thanks for confirming!
> >
> > > > Either way, we'll need *some* way to recover the original return addresss...
> > >
> > > At least it needs to dump the shadow stack so that we can analyze what
> > > happened.
> >
> > Sounds like a plan; as above I'll have a go at putting that together and will
> > dump the results here.
>
> Yeah, please try below patch.
>
> Thanks,
>
> ---
> arch/arm64/kernel/stacktrace.c | 10 +++++++++-
> include/linux/ftrace.h | 2 ++
> kernel/trace/fgraph.c | 24 ++++++++++++++++++++++++
> 3 files changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
> index 17f66a74c745..0eaba1bad599 100644
> --- a/arch/arm64/kernel/stacktrace.c
> +++ b/arch/arm64/kernel/stacktrace.c
> @@ -81,8 +81,16 @@ unwind_recover_return_address(struct unwind_state *state)
> unsigned long orig_pc;
> orig_pc = ftrace_graph_ret_addr(state->task, NULL, state->pc,
> (void *)state->fp);
> - if (WARN_ON_ONCE(state->pc == orig_pc))
> + if (WARN_ON_ONCE(state->pc == orig_pc)) {
> + static bool dumped;
> +
> + if (!dumped) {
> + pr_info("Dump: return_to_handler = %lx\n", (unsigned long)return_to_handler);
> + dumped = true;
> + fgraph_dump_ret_stack(state->task);
> + }
> return -EINVAL;
> + }
> state->pc = orig_pc;
> }
> #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index ad28daa507f7..cfb79977fdec 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -1258,6 +1258,8 @@ static inline void unpause_graph_tracing(void)
> {
> atomic_dec(¤t->tracing_graph_pause);
> }
> +
> +void fgraph_dump_ret_stack(struct task_struct *t);
> #else /* !CONFIG_FUNCTION_GRAPH_TRACER */
>
> #define __notrace_funcgraph
> diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> index 0f11f80bdd6c..5dd560fbacce 100644
> --- a/kernel/trace/fgraph.c
> +++ b/kernel/trace/fgraph.c
> @@ -437,6 +437,30 @@ get_ret_stack(struct task_struct *t, int offset, int *index)
> return RET_STACK(t, offset);
> }
>
> +void fgraph_dump_ret_stack(struct task_struct *t)
> +{
> + struct ftrace_ret_stack *ret_stack;
> + unsigned long val;
> + int i, offset, next;
> +
> + for (i = t->curr_ret_stack - 1; i > 0; i--) {
> + val = get_fgraph_entry(t, i);
> + pr_err(" ret_stack[%d]: %lx %pS type = %d, index = %d\n",
> + i, val, (void *)val, __get_type(val), __get_index(val));
> + }
> + offset = t->curr_ret_stack;
> + do {
> + ret_stack = get_ret_stack(t, offset, &next);
> + pr_err("ret_stack[%d]: %lx\n",
> + next + 1, (unsigned long)ret_stack);
> + if (ret_stack) {
> + pr_err("\tfunc: %ps, return:%ps\n",
> + (void *)ret_stack->func, (void *)ret_stack->ret);
> + }
> + offset = next;
> + } while (ret_stack);
> +}
> +
> /* Both enabled by default (can be cleared by function_graph tracer flags */
> static bool fgraph_sleep_time = true;
>
> --
> 2.34.1
>
> --
> Masami Hiramatsu (Google) <mhiramat@kernel.org>
>
^ permalink raw reply [flat|nested] 56+ messages in thread* Re: [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering
2024-01-11 11:01 ` Mark Rutland
@ 2024-01-11 13:45 ` Masami Hiramatsu
0 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu @ 2024-01-11 13:45 UTC (permalink / raw)
To: Mark Rutland
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Peter Zijlstra, Thomas Gleixner,
Guo Ren
Hi Mark,
On Thu, 11 Jan 2024 11:01:56 +0000
Mark Rutland <mark.rutland@arm.com> wrote:
> On Thu, Jan 11, 2024 at 11:15:33AM +0900, Masami Hiramatsu wrote:
> > Hi Mark,
> >
> > Thanks for the investigation.
>
> Hi!
>
> As a heads-up, I already figured out the problem and sent a fixup at:
>
> https://lore.kernel.org/lkml/ZZwEz8HsTa2IZE3L@FVFF77S0Q05N/
>
> ... and a more refined fix at:
>
> https://lore.kernel.org/lkml/ZZwOubTSbB_FucVz@FVFF77S0Q05N/
Oops, I missed it. And I also confirmed that.
>
> The gist was that before this patch, arm64 used the FP as the 'retp' value, but
> this patch changed that to the address of fregs->lr. This meant that the fgraph
> ret_stack contained all of the correct return addresses, but when the unwinder
> called ftrace_graph_ret_addr() with FP as the 'retp' value, it failed to match
> any entry in the ret_stack.
Yeah, this patch introduced new arm64 ftrace_graph_func(). and I missed
to pass the 'parent'... OK let me fix that.
>
> Since the fregs only exist transiently at function entry and exit, I'd prefer
> that we still use the FP as the 'retp' value, which is what I proposed in the
> fixups above.
OK. Let me add it.
Thank you!
>
> Thanks,
> Mark.
>
> > On Mon, 8 Jan 2024 12:25:55 +0000
> > Mark Rutland <mark.rutland@arm.com> wrote:
> >
> > > Hi,
> > >
> > > There's a bit more of an info-dump below; I'll go try to dump the fgraph shadow
> > > stack so that we can analyse this in more detail.
> > >
> > > On Mon, Jan 08, 2024 at 10:14:36AM +0900, Masami Hiramatsu wrote:
> > > > On Fri, 5 Jan 2024 17:09:10 +0000
> > > > Mark Rutland <mark.rutland@arm.com> wrote:
> > > >
> > > > > On Mon, Dec 18, 2023 at 10:13:46PM +0900, Masami Hiramatsu (Google) wrote:
> > > > > > From: Steven Rostedt (VMware) <rostedt@goodmis.org>
> > > > > >
> > > > > > Allow for instances to have their own ftrace_ops part of the fgraph_ops
> > > > > > that makes the funtion_graph tracer filter on the set_ftrace_filter file
> > > > > > of the instance and not the top instance.
> > > > > >
> > > > > > This also change how the function_graph handles multiple instances on the
> > > > > > shadow stack. Previously we use ARRAY type entries to record which one
> > > > > > is enabled, and this makes it a bitmap of the fgraph_array's indexes.
> > > > > > Previous function_graph_enter() expects calling back from
> > > > > > prepare_ftrace_return() function which is called back only once if it is
> > > > > > enabled. But this introduces different ftrace_ops for each fgraph
> > > > > > instance and those are called from ftrace_graph_func() one by one. Thus
> > > > > > we can not loop on the fgraph_array(), and need to reuse the ret_stack
> > > > > > pushed by the previous instance. Finding the ret_stack is easy because
> > > > > > we can check the ret_stack->func. But that is not enough for the self-
> > > > > > recursive tail-call case. Thus fgraph uses the bitmap entry to find it
> > > > > > is already set (this means that entry is for previous tail call).
> > > > > >
> > > > > > Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> > > > > > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> > > > >
> > > > > As a heads-up, while testing the topic/fprobe-on-fgraph branch on arm64, I get
> > > > > a warning which bisets down to this commit:
> > > >
> > > > Hmm, so does this happen when enabling function graph tracer?
> > >
> > > Yes; I see it during the function_graph boot-time self-test if I also enable
> > > CONFIG_IRQSOFF_TRACER=y. I can also trigger it regardless of
> > > CONFIG_IRQSOFF_TRACER if I cat /proc/self/stack with the function_graph tracer
> > > enabled (note that I hacked the unwinder to continue after failing to recover a
> > > return address):
> > >
> > > | # mount -t tracefs none /sys/kernel/tracing/
> > > | # echo function_graph > /sys/kernel/tracing/current_tracer
> > > | # cat /proc/self/stack
> > > | [ 37.469980] ------------[ cut here ]------------
> > > | [ 37.471503] WARNING: CPU: 2 PID: 174 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x2d8/0x338
> > > | [ 37.474381] Modules linked in:
> > > | [ 37.475501] CPU: 2 PID: 174 Comm: cat Not tainted 6.7.0-rc2-00026-gea1e68a341c2-dirty #15
> > > | [ 37.478133] Hardware name: linux,dummy-virt (DT)
> > > | [ 37.479670] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > > | [ 37.481923] pc : arch_stack_walk+0x2d8/0x338
> > > | [ 37.483373] lr : arch_stack_walk+0x1bc/0x338
> > > | [ 37.484818] sp : ffff8000835f3a90
> > > | [ 37.485974] x29: ffff8000835f3a90 x28: ffff8000835f3b80 x27: ffff8000835f3b38
> > > | [ 37.488405] x26: ffff000004341e00 x25: ffff8000835f4000 x24: ffff80008002df18
> > > | [ 37.490842] x23: ffff80008002df18 x22: ffff8000835f3b60 x21: ffff80008015d240
> > > | [ 37.493269] x20: ffff8000835f3b50 x19: ffff8000835f3b40 x18: 0000000000000000
> > > | [ 37.495704] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
> > > | [ 37.498144] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
> > > | [ 37.500579] x11: ffff800082b4d920 x10: ffff8000835f3a70 x9 : ffff8000800e55a0
> > > | [ 37.503021] x8 : ffff80008002df18 x7 : ffff000004341e00 x6 : 00000000ffffffff
> > > | [ 37.505452] x5 : 0000000000000000 x4 : ffff8000835f3e48 x3 : ffff8000835f3b80
> > > | [ 37.507888] x2 : ffff80008002df18 x1 : ffff000007f7b000 x0 : ffff80008002df18
> > > | [ 37.510319] Call trace:
> > > | [ 37.511202] arch_stack_walk+0x2d8/0x338
> > > | [ 37.512541] stack_trace_save_tsk+0x90/0x110
> > > | [ 37.514012] return_to_handler+0x0/0x48
> > > | [ 37.515336] return_to_handler+0x0/0x48
> > > | [ 37.516657] return_to_handler+0x0/0x48
> > > | [ 37.517985] return_to_handler+0x0/0x48
> > > | [ 37.519305] return_to_handler+0x0/0x48
> > > | [ 37.520623] return_to_handler+0x0/0x48
> > > | [ 37.521957] return_to_handler+0x0/0x48
> > > | [ 37.523272] return_to_handler+0x0/0x48
> > > | [ 37.524595] return_to_handler+0x0/0x48
> > > | [ 37.525931] return_to_handler+0x0/0x48
> > > | [ 37.527254] return_to_handler+0x0/0x48
> > > | [ 37.528564] el0t_64_sync_handler+0x120/0x130
> > > | [ 37.530046] el0t_64_sync+0x190/0x198
> > > | [ 37.531310] ---[ end trace 0000000000000000 ]---
> > > | [<0>] ftrace_stub_graph+0x8/0x8
> > > | [<0>] ftrace_stub_graph+0x8/0x8
> > > | [<0>] ftrace_stub_graph+0x8/0x8
> > > | [<0>] ftrace_stub_graph+0x8/0x8
> > > | [<0>] ftrace_stub_graph+0x8/0x8
> > > | [<0>] ftrace_stub_graph+0x8/0x8
> > > | [<0>] ftrace_stub_graph+0x8/0x8
> > > | [<0>] ftrace_stub_graph+0x8/0x8
> > > | [<0>] ftrace_stub_graph+0x8/0x8
> > > | [<0>] ftrace_stub_graph+0x8/0x8
> > > | [<0>] ftrace_stub_graph+0x8/0x8
> > > | [<0>] el0t_64_sync_handler+0x120/0x130
> > > | [<0>] el0t_64_sync+0x190/0x198
> >
> > Hmm, I haven't see this mode.
> >
> > >
> > > One interesting thing there is that there are two distinct failure modes: the
> > > unwind for the WARNING gives return_to_handler instead of the original return
> > > address, and the unwind returned from /proc/self/stack gives ftrace_stub_graph
> > > rather than the original return address.
> > >
> > > > >
> > > > > | Testing tracer function_graph:
> > > > > | ------------[ cut here ]------------
> > > > > | WARNING: CPU: 2 PID: 0 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x3c0/0x3d8
> > > > > | Modules linked in:
> > > > > | CPU: 2 PID: 0 Comm: swapper/2 Not tainted 6.7.0-rc2-00026-gea1e68a341c2 #12
> > > > > | Hardware name: linux,dummy-virt (DT)
> > > > > | pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > > > > | pc : arch_stack_walk+0x3c0/0x3d8
> > > > > | lr : arch_stack_walk+0x260/0x3d8
> > > > > | sp : ffff80008318be00
> > > > > | x29: ffff80008318be00 x28: ffff000003c0ae80 x27: 0000000000000000
> > > > > | x26: 0000000000000000 x25: ffff000003c0ae80 x24: 0000000000000000
> > > > > | x23: ffff8000800234c8 x22: ffff80008002dc30 x21: ffff800080035d10
> > > > > | x20: ffff80008318bee8 x19: ffff800080023460 x18: ffff800083453c68
> > > > > | x17: 0000000000000000 x16: ffff800083188000 x15: 000000008ccc5058
> > > > > | x14: 0000000000000004 x13: ffff800082b8c4f0 x12: 0000000000000000
> > > > > | x11: ffff800081fba9b0 x10: ffff80008318bff0 x9 : ffff800080010798
> > > > > | x8 : ffff80008002dc30 x7 : ffff000003c0ae80 x6 : 00000000ffffffff
> > > > > | x5 : 0000000000000000 x4 : ffff8000832a3c18 x3 : ffff80008318bff0
> > > > > | x2 : ffff80008002dc30 x1 : ffff80008002dc30 x0 : ffff80008002dc30
> > > > > | Call trace:
> > > > > | arch_stack_walk+0x3c0/0x3d8
> > > > > | return_address+0x40/0x80
> > > > > | trace_hardirqs_on+0x8c/0x198
> > > > > | __do_softirq+0xe8/0x440
> > > > > | ---[ end trace 0000000000000000 ]---
> > >
> > > With the smae hack to continue after failing to recover a return address, the
> > > failure in the selftest looks like:
> > >
> > > | ------------[ cut here ]------------
> > > | WARNING: CPU: 7 PID: 0 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x2d8/0x338
> > > | Modules linked in:
> > > | CPU: 7 PID: 0 Comm: swapper/7 Not tainted 6.7.0-rc2-00026-gea1e68a341c2-dirty #14
> > > | Hardware name: linux,dummy-virt (DT)
> > > | pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > > | pc : arch_stack_walk+0x2d8/0x338
> > > | lr : arch_stack_walk+0x1bc/0x338
> > > | sp : ffff8000830c3e20
> > > | x29: ffff8000830c3e20 x28: ffff8000830c3ff0 x27: ffff8000830c3ec8
> > > | x26: ffff0000037e0000 x25: ffff8000830c4000 x24: ffff80008002e080
> > > | x23: ffff80008002e080 x22: ffff8000830c3ee8 x21: ffff800080023418
> > > | x20: ffff8000830c3f50 x19: ffff8000830c3f40 x18: ffffffffffffffff
> > > | x17: 0000000000000000 x16: ffff8000830c0000 x15: 0000000000000000
> > > | x14: 0000000000000002 x13: ffff8000800360f8 x12: ffff800080028330
> > > | x11: ffff800081f4a978 x10: ffff8000830c3ff0 x9 : ffff800080010798
> > > | x8 : ffff80008002e080 x7 : ffff0000037e0000 x6 : 00000000ffffffff
> > > | x5 : 0000000000000000 x4 : ffff8000831dbc18 x3 : ffff8000830c3ff0
> > > | x2 : ffff80008002e080 x1 : ffff0000040a3000 x0 : ffff80008002e080
> > > | Call trace:
> > > | arch_stack_walk+0x2d8/0x338
> > > | return_address+0x40/0x80
> > > | trace_hardirqs_on+0x8c/0x198
> > > | __do_softirq+0xe8/0x43c
> > > | return_to_handler+0x0/0x48
> > > | return_to_handler+0x0/0x48
> > > | do_softirq_own_stack+0x24/0x38
> > > | return_to_handler+0x0/0x48
> > > | el1_interrupt+0x38/0x68
> > > | el1h_64_irq_handler+0x18/0x28
> > > | el1h_64_irq+0x64/0x68
> > > | default_idle_call+0x70/0x178
> > > | do_idle+0x228/0x290
> > > | cpu_startup_entry+0x40/0x50
> > > | secondary_start_kernel+0x138/0x160
> > > | __secondary_switched+0xb8/0xc0
> > > | ---[ end trace 0000000000000000 ]---
> >
> > I usually see this and reproduced. Here, I also add a dump of shadow stack.
> > It seems that the unwinder goes to the bottome of the shadow stack.
> >
> > /sys/kernel/tracing # echo function_graph > current_tracer
> > [ 89.887750] ------------[ cut here ]------------
> > [ 89.889864] Dump: return_to_handler = ffffb45fc6a2f1e8
> > [ 89.891833] ret_stack[20]: 20406 0x20406 type = 1, index = 6
> > [ 89.896118] ret_stack[19]: ffff800080003be8 0xffff800080003be8 type = 2, index = 1000
> > [ 89.896233] ret_stack[18]: ffff800080003c20 0xffff800080003c20 type = 3, index = 32
> > [ 89.896362] ret_stack[17]: 0 0x0 type = 0, index = 0
> > [ 89.896425] ret_stack[16]: 14edac7710 0x14edac7710 type = 1, index = 784
> > [ 89.896635] ret_stack[15]: ffffb45fc6a1610c call_break_hook+0x4/0x108 type = 0, index = 268
> > [ 89.897882] ret_stack[14]: ffffb45fc6a162fc brk_handler+0x24/0x70 type = 0, index = 764
> > [ 89.898139] ret_stack[13]: 20406 0x20406 type = 1, index = 6
> > [ 89.898337] ret_stack[12]: ffff800080003c08 0xffff800080003c08 type = 3, index = 8
> > [ 89.898554] ret_stack[11]: ffff800080003c40 0xffff800080003c40 type = 3, index = 64
> > [ 89.898645] ret_stack[10]: 0 0x0 type = 0, index = 0
> > [ 89.898832] ret_stack[9]: 14eda8f920 0x14eda8f920 type = 2, index = 288
> > [ 89.899069] ret_stack[8]: ffffb45fc6a162dc brk_handler+0x4/0x70 type = 0, index = 732
> > [ 89.899230] ret_stack[7]: ffffb45fc6a36c24 do_debug_exception+0x74/0x108 type = 3, index = 36
> > [ 89.899385] ret_stack[6]: 20406 0x20406 type = 1, index = 6
> > [ 89.899456] ret_stack[5]: ffff800080003fb8 0xffff800080003fb8 type = 3, index = 952
> > [ 89.899518] ret_stack[4]: ffff800080003ff0 0xffff800080003ff0 type = 3, index = 1008
> > [ 89.899578] ret_stack[3]: ffff62a80534d21c 0xffff62a80534d21c type = 0, index = 540
> > [ 89.899637] ret_stack[2]: 14ed8ed2e0 0x14ed8ed2e0 type = 0, index = 736
> > [ 89.899695] ret_stack[1]: ffffb45fc6a1069c __do_softirq+0x4/0x4f0 type = 1, index = 668
> > [ 89.899986] ret_stack[15]: ffff62a80534d070
> > [ 89.900221] func: call_break_hook, return:brk_handler
> > [ 89.901025] ret_stack[8]: ffff62a80534d038
> > [ 89.901223] func: brk_handler, return:do_debug_exception
> > [ 89.901450] ret_stack[1]: ffff62a80534d000
> > [ 89.901501] func: __do_softirq, return:____do_softirq
> > [ 89.901693] ret_stack[1]: 0
> > [ 90.015738] WARNING: CPU: 0 PID: 0 at arch/arm64/kernel/stacktrace.c:84 arch_stack_walk+0x2d8/0x380
> > [ 90.022314] Modules linked in:
> > [ 90.032375] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G N 6.7.0-rc8-00036-g3897e34e8ae2-dirty #79
> > [ 90.038797] Hardware name: linux,dummy-virt (DT)
> > [ 90.044170] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> > [ 90.048879] pc : arch_stack_walk+0x2d8/0x380
> > [ 90.052222] lr : arch_stack_walk+0x248/0x380
> > [ 90.055635] sp : ffff800080003e20
> > [ 90.058147] x29: ffff800080003e20 x28: ffffb45fc91993c0 x27: 0000000000000000
> > [ 90.063705] x26: 0000000000000000 x25: 0000000000000000 x24: ffffb45fc918fb40
> > [ 90.068946] x23: ffffb45fc6a247b8 x22: ffffb45fc6a2f1e8 x21: ffffb45fc6a35b30
> > [ 90.074894] x20: ffff800080003ef8 x19: ffffb45fc6a24750 x18: 0000000000000000
> > [ 90.078796] x17: 0000000000000000 x16: ffff800080000000 x15: 0000ffffff477588
> > [ 90.084310] x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000
> > [ 90.088898] x11: ffffb45fc924ca08 x10: ffff62a8040341c0 x9 : ffffb45fc6a10760
> > [ 90.094430] x8 : ffffb45fc6a2f1e8 x7 : ffffb45fc91993c0 x6 : ffff62a80534d000
> > [ 90.099829] x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff800080003ff0
> > [ 90.104442] x2 : ffffb45fc6a2f1e8 x1 : ffffb45fc6a2f1e8 x0 : ffffb45fc6a2f1e8
> > [ 90.111735] Call trace:
> > [ 90.114923] arch_stack_walk+0x2d8/0x380
> > [ 90.118820] return_address+0x40/0x80
> > [ 90.122057] trace_hardirqs_on+0xa0/0x100
> > [ 90.125001] __do_softirq+0xec/0x4f0
> > [ 90.130907] irq event stamp: 102709
> > [ 90.134223] hardirqs last enabled at (102707): [<ffffb45fc7af51d8>] default_idle_call+0xa0/0x160
> > [ 90.140612] hardirqs last disabled at (102708): [<ffffb45fc7af26ec>] el1_interrupt+0x24/0x68
> > [ 90.145877] softirqs last enabled at (102702): [<ffffb45fc6a10b40>] __do_softirq+0x4a8/0x4f0
> > [ 90.148952] softirqs last disabled at (102709): [<ffffb45fc6a2f1e8>] return_to_handler+0x0/0x50
> > [ 90.152834] ---[ end trace 0000000000000000 ]---
> >
> >
> > >
> > > The portion of the trace with:
> > >
> > > __do_softirq+0xe8/0x43c
> > > return_to_handler+0x0/0x48
> > > return_to_handler+0x0/0x48
> > > do_softirq_own_stack+0x24/0x38
> > >
> > > ... should be something like:
> > >
> > > __do_softirq
> > > ____do_softirq
> > > call_on_irq_stack // asm trampoline, not traceable
> > > do_softirq_own_stack
> > >
> > > The generated assembly for do_softirq_own_stack(), ____do_softirq(), and
> > > __do_softirq() is as I'd expect with no tail calls, so I can't see an obvious
> > > reason the return address cannot be recovered correctly.
> >
> > My question is that even if unwinder fails, the program runs normally.
> > Isn't it a real stack entry?
> >
> > >
> > > > > That's a warning in arm64's unwind_recover_return_address() function, which
> > > > > fires when ftrace_graph_ret_addr() finds return_to_handler:
> > > > >
> > > > > if (state->task->ret_stack &&
> > > > > (state->pc == (unsigned long)return_to_handler)) {
> > > > > unsigned long orig_pc;
> > > > > orig_pc = ftrace_graph_ret_addr(state->task, NULL, state->pc,
> > > > > (void *)state->fp);
> > > > > if (WARN_ON_ONCE(state->pc == orig_pc))
> > > > > return -EINVAL;
> > > > > state->pc = orig_pc;
> > > > > }
> > > > >
> > > > > The rationale there is that since tail calls are (currently) disabled on arm64,
> > > > > the only reason for ftrace_graph_ret_addr() to return return_to_handler is when
> > > > > it fails to find the original return address.
> > > >
> > > > Yes. what about FP check?
> > >
> > > Do you mean HAVE_FUNCTION_GRAPH_FP_TEST?
> > >
> > > That is enabled, and there are warnings from ftrace_pop_return_trace(), so I
> > > believe push/pop is balanced.
> >
> > OK.
> >
> > >
> > > We also have HAVE_FUNCTION_GRAPH_RET_ADDR_PTR, but since the return address is
> > > not on the stack at the point function-entry is intercepted we use the FP as
> > > the retp value -- in the absence of tail calls this will be different between a
> > > caller and callee.
> > >
> > > > > Does this change make it legitimate for ftrace_graph_ret_addr() to return
> > > > > return_to_handler in other cases, or is that a bug?
> > > >
> > > > It should be a bug to be fixed.
> > >
> > > Cool; thanks for confirming!
> > >
> > > > > Either way, we'll need *some* way to recover the original return addresss...
> > > >
> > > > At least it needs to dump the shadow stack so that we can analyze what
> > > > happened.
> > >
> > > Sounds like a plan; as above I'll have a go at putting that together and will
> > > dump the results here.
> >
> > Yeah, please try below patch.
> >
> > Thanks,
> >
> > ---
> > arch/arm64/kernel/stacktrace.c | 10 +++++++++-
> > include/linux/ftrace.h | 2 ++
> > kernel/trace/fgraph.c | 24 ++++++++++++++++++++++++
> > 3 files changed, 35 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
> > index 17f66a74c745..0eaba1bad599 100644
> > --- a/arch/arm64/kernel/stacktrace.c
> > +++ b/arch/arm64/kernel/stacktrace.c
> > @@ -81,8 +81,16 @@ unwind_recover_return_address(struct unwind_state *state)
> > unsigned long orig_pc;
> > orig_pc = ftrace_graph_ret_addr(state->task, NULL, state->pc,
> > (void *)state->fp);
> > - if (WARN_ON_ONCE(state->pc == orig_pc))
> > + if (WARN_ON_ONCE(state->pc == orig_pc)) {
> > + static bool dumped;
> > +
> > + if (!dumped) {
> > + pr_info("Dump: return_to_handler = %lx\n", (unsigned long)return_to_handler);
> > + dumped = true;
> > + fgraph_dump_ret_stack(state->task);
> > + }
> > return -EINVAL;
> > + }
> > state->pc = orig_pc;
> > }
> > #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
> > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> > index ad28daa507f7..cfb79977fdec 100644
> > --- a/include/linux/ftrace.h
> > +++ b/include/linux/ftrace.h
> > @@ -1258,6 +1258,8 @@ static inline void unpause_graph_tracing(void)
> > {
> > atomic_dec(¤t->tracing_graph_pause);
> > }
> > +
> > +void fgraph_dump_ret_stack(struct task_struct *t);
> > #else /* !CONFIG_FUNCTION_GRAPH_TRACER */
> >
> > #define __notrace_funcgraph
> > diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> > index 0f11f80bdd6c..5dd560fbacce 100644
> > --- a/kernel/trace/fgraph.c
> > +++ b/kernel/trace/fgraph.c
> > @@ -437,6 +437,30 @@ get_ret_stack(struct task_struct *t, int offset, int *index)
> > return RET_STACK(t, offset);
> > }
> >
> > +void fgraph_dump_ret_stack(struct task_struct *t)
> > +{
> > + struct ftrace_ret_stack *ret_stack;
> > + unsigned long val;
> > + int i, offset, next;
> > +
> > + for (i = t->curr_ret_stack - 1; i > 0; i--) {
> > + val = get_fgraph_entry(t, i);
> > + pr_err(" ret_stack[%d]: %lx %pS type = %d, index = %d\n",
> > + i, val, (void *)val, __get_type(val), __get_index(val));
> > + }
> > + offset = t->curr_ret_stack;
> > + do {
> > + ret_stack = get_ret_stack(t, offset, &next);
> > + pr_err("ret_stack[%d]: %lx\n",
> > + next + 1, (unsigned long)ret_stack);
> > + if (ret_stack) {
> > + pr_err("\tfunc: %ps, return:%ps\n",
> > + (void *)ret_stack->func, (void *)ret_stack->ret);
> > + }
> > + offset = next;
> > + } while (ret_stack);
> > +}
> > +
> > /* Both enabled by default (can be cleared by function_graph tracer flags */
> > static bool fgraph_sleep_time = true;
> >
> > --
> > 2.34.1
> >
> > --
> > Masami Hiramatsu (Google) <mhiramat@kernel.org>
> >
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 56+ messages in thread
* [PATCH v5 12/34] function_graph: Use a simple LRU for fgraph_array index number
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (10 preceding siblings ...)
2023-12-18 13:13 ` [PATCH v5 11/34] function_graph: Have the instances use their own ftrace_ops for filtering Masami Hiramatsu (Google)
@ 2023-12-18 13:13 ` Masami Hiramatsu (Google)
2023-12-18 13:14 ` [PATCH v5 13/34] function_graph: Add "task variables" per task for fgraph_ops Masami Hiramatsu (Google)
` (21 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:13 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Since the fgraph_array index is used for the bitmap on the shadow
stack, it may leave some entries after a function_graph instance is
removed. Thus if another instance reuses the fgraph_array index soon
after releasing it, the fgraph may confuse to call the newer callback
for the entries which are pushed by the older instance.
To avoid reusing the fgraph_array index soon after releasing, introduce
a simple LRU table for managing the index number. This will reduce the
possibility of this confusion.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v5:
- Fix the underflow bug in fgraph_lru_release_index() and return 0
if the release is succeded.
Changes in v4:
- Newly added.
---
kernel/trace/fgraph.c | 67 ++++++++++++++++++++++++++++++++++---------------
1 file changed, 47 insertions(+), 20 deletions(-)
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 6f537ebd3ed7..aa5e4ec9fbb2 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -99,10 +99,44 @@ enum {
DEFINE_STATIC_KEY_FALSE(kill_ftrace_graph);
int ftrace_graph_active;
-static int fgraph_array_cnt;
-
static struct fgraph_ops *fgraph_array[FGRAPH_ARRAY_SIZE];
+/* LRU index table for fgraph_array */
+static int fgraph_lru_table[FGRAPH_ARRAY_SIZE];
+static int fgraph_lru_next;
+static int fgraph_lru_last;
+
+static void fgraph_lru_init(void)
+{
+ int i;
+
+ for (i = 0; i < FGRAPH_ARRAY_SIZE; i++)
+ fgraph_lru_table[i] = i;
+}
+
+static int fgraph_lru_release_index(int idx)
+{
+ if (idx < 0 || idx >= FGRAPH_ARRAY_SIZE ||
+ fgraph_lru_table[fgraph_lru_last] != -1)
+ return -1;
+
+ fgraph_lru_table[fgraph_lru_last] = idx;
+ fgraph_lru_last = (fgraph_lru_last + 1) % FGRAPH_ARRAY_SIZE;
+ return 0;
+}
+
+static int fgraph_lru_alloc_index(void)
+{
+ int idx = fgraph_lru_table[fgraph_lru_next];
+
+ if (idx == -1)
+ return -1;
+
+ fgraph_lru_table[fgraph_lru_next] = -1;
+ fgraph_lru_next = (fgraph_lru_next + 1) % FGRAPH_ARRAY_SIZE;
+ return idx;
+}
+
static inline int get_ret_stack_index(struct task_struct *t, int offset)
{
return t->ret_stack[offset] & FGRAPH_RET_INDEX_MASK;
@@ -367,7 +401,7 @@ int function_graph_enter(unsigned long ret, unsigned long func,
if (index < 0)
goto out;
- for (i = 0; i < fgraph_array_cnt; i++) {
+ for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) {
struct fgraph_ops *gops = fgraph_array[i];
if (gops == &fgraph_stub)
@@ -932,21 +966,17 @@ int register_ftrace_graph(struct fgraph_ops *gops)
/* The array must always have real data on it */
for (i = 0; i < FGRAPH_ARRAY_SIZE; i++)
fgraph_array[i] = &fgraph_stub;
+ fgraph_lru_init();
}
- /* Look for an available spot */
- for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) {
- if (fgraph_array[i] == &fgraph_stub)
- break;
- }
- if (i >= FGRAPH_ARRAY_SIZE) {
+ i = fgraph_lru_alloc_index();
+ if (i < 0 ||
+ WARN_ON_ONCE(fgraph_array[i] != &fgraph_stub)) {
ret = -EBUSY;
goto out;
}
fgraph_array[i] = gops;
- if (i + 1 > fgraph_array_cnt)
- fgraph_array_cnt = i + 1;
gops->idx = i;
ftrace_graph_active++;
@@ -976,25 +1006,22 @@ int register_ftrace_graph(struct fgraph_ops *gops)
void unregister_ftrace_graph(struct fgraph_ops *gops)
{
int command = 0;
- int i;
mutex_lock(&ftrace_lock);
if (unlikely(!ftrace_graph_active))
goto out;
- if (unlikely(gops->idx < 0 || gops->idx >= fgraph_array_cnt))
+ if (unlikely(gops->idx < 0 || gops->idx >= FGRAPH_ARRAY_SIZE))
+ goto out;
+
+ if (WARN_ON_ONCE(fgraph_array[gops->idx] != gops))
goto out;
- WARN_ON_ONCE(fgraph_array[gops->idx] != gops);
+ if (fgraph_lru_release_index(gops->idx) < 0)
+ goto out;
fgraph_array[gops->idx] = &fgraph_stub;
- if (gops->idx + 1 == fgraph_array_cnt) {
- i = gops->idx;
- while (i >= 0 && fgraph_array[i] == &fgraph_stub)
- i--;
- fgraph_array_cnt = i + 1;
- }
ftrace_graph_active--;
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 13/34] function_graph: Add "task variables" per task for fgraph_ops
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (11 preceding siblings ...)
2023-12-18 13:13 ` [PATCH v5 12/34] function_graph: Use a simple LRU for fgraph_array index number Masami Hiramatsu (Google)
@ 2023-12-18 13:14 ` Masami Hiramatsu (Google)
2023-12-18 13:14 ` [PATCH v5 14/34] function_graph: Move set_graph_function tests to shadow stack global var Masami Hiramatsu (Google)
` (20 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:14 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
Add a "task variables" array on the tasks shadow ret_stack that is the
size of longs for each possible registered fgraph_ops. That's a total
of 16, taking up 8 * 16 = 128 bytes (out of a page size 4k).
This will allow for fgraph_ops to do specific features on a per task basis
having a way to maintain state for each task.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Move fgraph_ops::idx to previous patch in the series.
Changes in v2:
- Make description lines shorter than 76 chars.
---
include/linux/ftrace.h | 1 +
kernel/trace/fgraph.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 70 insertions(+), 1 deletion(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index c431a33fe789..09ca4bba63f2 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1116,6 +1116,7 @@ ftrace_graph_get_ret_stack(struct task_struct *task, int idx);
unsigned long ftrace_graph_ret_addr(struct task_struct *task, int *idx,
unsigned long ret, unsigned long *retp);
+unsigned long *fgraph_get_task_var(struct fgraph_ops *gops);
/*
* Sometimes we don't want to trace a function with the function
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index aa5e4ec9fbb2..6e52c4989ef3 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -92,10 +92,18 @@ enum {
#define SHADOW_STACK_SIZE (PAGE_SIZE)
#define SHADOW_STACK_INDEX (SHADOW_STACK_SIZE / sizeof(long))
/* Leave on a buffer at the end */
-#define SHADOW_STACK_MAX_INDEX (SHADOW_STACK_INDEX - (FGRAPH_RET_INDEX + 1))
+#define SHADOW_STACK_MAX_INDEX \
+ (SHADOW_STACK_INDEX - (FGRAPH_RET_INDEX + 1 + FGRAPH_ARRAY_SIZE))
#define RET_STACK(t, index) ((struct ftrace_ret_stack *)(&(t)->ret_stack[index]))
+/*
+ * Each fgraph_ops has a reservered unsigned long at the end (top) of the
+ * ret_stack to store task specific state.
+ */
+#define SHADOW_STACK_TASK_VARS(ret_stack) \
+ ((unsigned long *)(&(ret_stack)[SHADOW_STACK_INDEX - FGRAPH_ARRAY_SIZE]))
+
DEFINE_STATIC_KEY_FALSE(kill_ftrace_graph);
int ftrace_graph_active;
@@ -182,6 +190,44 @@ static void return_run(struct ftrace_graph_ret *trace, struct fgraph_ops *ops)
{
}
+static void ret_stack_set_task_var(struct task_struct *t, int idx, long val)
+{
+ unsigned long *gvals = SHADOW_STACK_TASK_VARS(t->ret_stack);
+
+ gvals[idx] = val;
+}
+
+static unsigned long *
+ret_stack_get_task_var(struct task_struct *t, int idx)
+{
+ unsigned long *gvals = SHADOW_STACK_TASK_VARS(t->ret_stack);
+
+ return &gvals[idx];
+}
+
+static void ret_stack_init_task_vars(unsigned long *ret_stack)
+{
+ unsigned long *gvals = SHADOW_STACK_TASK_VARS(ret_stack);
+
+ memset(gvals, 0, sizeof(*gvals) * FGRAPH_ARRAY_SIZE);
+}
+
+/**
+ * fgraph_get_task_var - retrieve a task specific state variable
+ * @gops: The ftrace_ops that owns the task specific variable
+ *
+ * Every registered fgraph_ops has a task state variable
+ * reserved on the task's ret_stack. This function returns the
+ * address to that variable.
+ *
+ * Returns the address to the fgraph_ops @gops tasks specific
+ * unsigned long variable.
+ */
+unsigned long *fgraph_get_task_var(struct fgraph_ops *gops)
+{
+ return ret_stack_get_task_var(current, gops->idx);
+}
+
/*
* @offset: The index into @t->ret_stack to find the ret_stack entry
* @index: Where to place the index into @t->ret_stack of that entry
@@ -788,6 +834,7 @@ static int alloc_retstack_tasklist(unsigned long **ret_stack_list)
if (t->ret_stack == NULL) {
atomic_set(&t->trace_overrun, 0);
+ ret_stack_init_task_vars(ret_stack_list[start]);
t->curr_ret_stack = 0;
t->curr_ret_depth = -1;
/* Make sure the tasks see the 0 first: */
@@ -848,6 +895,7 @@ static void
graph_init_task(struct task_struct *t, unsigned long *ret_stack)
{
atomic_set(&t->trace_overrun, 0);
+ ret_stack_init_task_vars(ret_stack);
t->ftrace_timestamp = 0;
t->curr_ret_stack = 0;
t->curr_ret_depth = -1;
@@ -946,6 +994,24 @@ static int start_graph_tracing(void)
return ret;
}
+static void init_task_vars(int idx)
+{
+ struct task_struct *g, *t;
+ int cpu;
+
+ for_each_online_cpu(cpu) {
+ if (idle_task(cpu)->ret_stack)
+ ret_stack_set_task_var(idle_task(cpu), idx, 0);
+ }
+
+ read_lock(&tasklist_lock);
+ for_each_process_thread(g, t) {
+ if (t->ret_stack)
+ ret_stack_set_task_var(t, idx, 0);
+ }
+ read_unlock(&tasklist_lock);
+}
+
int register_ftrace_graph(struct fgraph_ops *gops)
{
int command = 0;
@@ -995,6 +1061,8 @@ int register_ftrace_graph(struct fgraph_ops *gops)
ftrace_graph_return = return_run;
ftrace_graph_entry = entry_run;
command = FTRACE_START_FUNC_RET;
+ } else {
+ init_task_vars(gops->idx);
}
ret = ftrace_startup(&gops->ops, command);
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 14/34] function_graph: Move set_graph_function tests to shadow stack global var
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (12 preceding siblings ...)
2023-12-18 13:14 ` [PATCH v5 13/34] function_graph: Add "task variables" per task for fgraph_ops Masami Hiramatsu (Google)
@ 2023-12-18 13:14 ` Masami Hiramatsu (Google)
2023-12-18 13:14 ` [PATCH v5 15/34] function_graph: Move graph depth stored data " Masami Hiramatsu (Google)
` (19 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:14 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
The use of the task->trace_recursion for the logic used for the
set_graph_funnction was a bit of an abuse of that variable. Now that there
exists global vars that are per stack for registered graph traces, use that
instead.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
include/linux/trace_recursion.h | 5 +----
kernel/trace/trace.h | 32 +++++++++++++++++++++-----------
kernel/trace/trace_functions_graph.c | 6 +++---
kernel/trace/trace_irqsoff.c | 4 ++--
kernel/trace/trace_sched_wakeup.c | 4 ++--
5 files changed, 29 insertions(+), 22 deletions(-)
diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h
index d48cd92d2364..2efd5ec46d7f 100644
--- a/include/linux/trace_recursion.h
+++ b/include/linux/trace_recursion.h
@@ -44,9 +44,6 @@ enum {
*/
TRACE_IRQ_BIT,
- /* Set if the function is in the set_graph_function file */
- TRACE_GRAPH_BIT,
-
/*
* In the very unlikely case that an interrupt came in
* at a start of graph tracing, and we want to trace
@@ -60,7 +57,7 @@ enum {
* that preempted a softirq start of a function that
* preempted normal context!!!! Luckily, it can't be
* greater than 3, so the next two bits are a mask
- * of what the depth is when we set TRACE_GRAPH_BIT
+ * of what the depth is when we set TRACE_GRAPH_FL
*/
TRACE_GRAPH_DEPTH_START_BIT,
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 02edfdb68933..3b9266aeb43b 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -894,11 +894,16 @@ extern void init_array_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops
extern int allocate_fgraph_ops(struct trace_array *tr, struct ftrace_ops *ops);
extern void free_fgraph_ops(struct trace_array *tr);
+enum {
+ TRACE_GRAPH_FL = 1,
+};
+
#ifdef CONFIG_DYNAMIC_FTRACE
extern struct ftrace_hash __rcu *ftrace_graph_hash;
extern struct ftrace_hash __rcu *ftrace_graph_notrace_hash;
-static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
+static inline int
+ftrace_graph_addr(unsigned long *task_var, struct ftrace_graph_ent *trace)
{
unsigned long addr = trace->func;
int ret = 0;
@@ -920,12 +925,11 @@ static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
}
if (ftrace_lookup_ip(hash, addr)) {
-
/*
* This needs to be cleared on the return functions
* when the depth is zero.
*/
- trace_recursion_set(TRACE_GRAPH_BIT);
+ *task_var |= TRACE_GRAPH_FL;
trace_recursion_set_depth(trace->depth);
/*
@@ -945,11 +949,14 @@ static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
return ret;
}
-static inline void ftrace_graph_addr_finish(struct ftrace_graph_ret *trace)
+static inline void
+ftrace_graph_addr_finish(struct fgraph_ops *gops, struct ftrace_graph_ret *trace)
{
- if (trace_recursion_test(TRACE_GRAPH_BIT) &&
+ unsigned long *task_var = fgraph_get_task_var(gops);
+
+ if ((*task_var & TRACE_GRAPH_FL) &&
trace->depth == trace_recursion_depth())
- trace_recursion_clear(TRACE_GRAPH_BIT);
+ *task_var &= ~TRACE_GRAPH_FL;
}
static inline int ftrace_graph_notrace_addr(unsigned long addr)
@@ -976,7 +983,7 @@ static inline int ftrace_graph_notrace_addr(unsigned long addr)
}
#else
-static inline int ftrace_graph_addr(struct ftrace_graph_ent *trace)
+static inline int ftrace_graph_addr(unsigned long *task_var, struct ftrace_graph_ent *trace)
{
return 1;
}
@@ -985,17 +992,20 @@ static inline int ftrace_graph_notrace_addr(unsigned long addr)
{
return 0;
}
-static inline void ftrace_graph_addr_finish(struct ftrace_graph_ret *trace)
+static inline void ftrace_graph_addr_finish(struct fgraph_ops *gops, struct ftrace_graph_ret *trace)
{ }
#endif /* CONFIG_DYNAMIC_FTRACE */
extern unsigned int fgraph_max_depth;
-static inline bool ftrace_graph_ignore_func(struct ftrace_graph_ent *trace)
+static inline bool
+ftrace_graph_ignore_func(struct fgraph_ops *gops, struct ftrace_graph_ent *trace)
{
+ unsigned long *task_var = fgraph_get_task_var(gops);
+
/* trace it when it is-nested-in or is a function enabled. */
- return !(trace_recursion_test(TRACE_GRAPH_BIT) ||
- ftrace_graph_addr(trace)) ||
+ return !((*task_var & TRACE_GRAPH_FL) ||
+ ftrace_graph_addr(task_var, trace)) ||
(trace->depth < 0) ||
(fgraph_max_depth && trace->depth >= fgraph_max_depth);
}
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 7f30652f0e97..66cce73e94f8 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -160,7 +160,7 @@ int trace_graph_entry(struct ftrace_graph_ent *trace,
if (!ftrace_trace_task(tr))
return 0;
- if (ftrace_graph_ignore_func(trace))
+ if (ftrace_graph_ignore_func(gops, trace))
return 0;
if (ftrace_graph_ignore_irqs())
@@ -247,7 +247,7 @@ void trace_graph_return(struct ftrace_graph_ret *trace,
long disabled;
int cpu;
- ftrace_graph_addr_finish(trace);
+ ftrace_graph_addr_finish(gops, trace);
if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
@@ -269,7 +269,7 @@ void trace_graph_return(struct ftrace_graph_ret *trace,
static void trace_graph_thresh_return(struct ftrace_graph_ret *trace,
struct fgraph_ops *gops)
{
- ftrace_graph_addr_finish(trace);
+ ftrace_graph_addr_finish(gops, trace);
if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index 5478f4c4f708..fce064e20570 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -184,7 +184,7 @@ static int irqsoff_graph_entry(struct ftrace_graph_ent *trace,
unsigned int trace_ctx;
int ret;
- if (ftrace_graph_ignore_func(trace))
+ if (ftrace_graph_ignore_func(gops, trace))
return 0;
/*
* Do not trace a function if it's filtered by set_graph_notrace.
@@ -214,7 +214,7 @@ static void irqsoff_graph_return(struct ftrace_graph_ret *trace,
unsigned long flags;
unsigned int trace_ctx;
- ftrace_graph_addr_finish(trace);
+ ftrace_graph_addr_finish(gops, trace);
if (!func_prolog_dec(tr, &data, &flags))
return;
diff --git a/kernel/trace/trace_sched_wakeup.c b/kernel/trace/trace_sched_wakeup.c
index 49bcc812652c..130ca7e7787e 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -120,7 +120,7 @@ static int wakeup_graph_entry(struct ftrace_graph_ent *trace,
unsigned int trace_ctx;
int ret = 0;
- if (ftrace_graph_ignore_func(trace))
+ if (ftrace_graph_ignore_func(gops, trace))
return 0;
/*
* Do not trace a function if it's filtered by set_graph_notrace.
@@ -149,7 +149,7 @@ static void wakeup_graph_return(struct ftrace_graph_ret *trace,
struct trace_array_cpu *data;
unsigned int trace_ctx;
- ftrace_graph_addr_finish(trace);
+ ftrace_graph_addr_finish(gops, trace);
if (!func_prolog_preempt_disable(tr, &data, &trace_ctx))
return;
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 15/34] function_graph: Move graph depth stored data to shadow stack global var
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (13 preceding siblings ...)
2023-12-18 13:14 ` [PATCH v5 14/34] function_graph: Move set_graph_function tests to shadow stack global var Masami Hiramatsu (Google)
@ 2023-12-18 13:14 ` Masami Hiramatsu (Google)
2023-12-18 13:14 ` [PATCH v5 16/34] function_graph: Move graph notrace bit " Masami Hiramatsu (Google)
` (18 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:14 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
The use of the task->trace_recursion for the logic used for the function
graph depth was a bit of an abuse of that variable. Now that there
exists global vars that are per stack for registered graph traces, use that
instead.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
include/linux/trace_recursion.h | 29 -----------------------------
kernel/trace/trace.h | 34 ++++++++++++++++++++++++++++++++--
2 files changed, 32 insertions(+), 31 deletions(-)
diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h
index 2efd5ec46d7f..00e792bf148d 100644
--- a/include/linux/trace_recursion.h
+++ b/include/linux/trace_recursion.h
@@ -44,25 +44,6 @@ enum {
*/
TRACE_IRQ_BIT,
- /*
- * In the very unlikely case that an interrupt came in
- * at a start of graph tracing, and we want to trace
- * the function in that interrupt, the depth can be greater
- * than zero, because of the preempted start of a previous
- * trace. In an even more unlikely case, depth could be 2
- * if a softirq interrupted the start of graph tracing,
- * followed by an interrupt preempting a start of graph
- * tracing in the softirq, and depth can even be 3
- * if an NMI came in at the start of an interrupt function
- * that preempted a softirq start of a function that
- * preempted normal context!!!! Luckily, it can't be
- * greater than 3, so the next two bits are a mask
- * of what the depth is when we set TRACE_GRAPH_FL
- */
-
- TRACE_GRAPH_DEPTH_START_BIT,
- TRACE_GRAPH_DEPTH_END_BIT,
-
/*
* To implement set_graph_notrace, if this bit is set, we ignore
* function graph tracing of called functions, until the return
@@ -78,16 +59,6 @@ enum {
#define trace_recursion_clear(bit) do { (current)->trace_recursion &= ~(1<<(bit)); } while (0)
#define trace_recursion_test(bit) ((current)->trace_recursion & (1<<(bit)))
-#define trace_recursion_depth() \
- (((current)->trace_recursion >> TRACE_GRAPH_DEPTH_START_BIT) & 3)
-#define trace_recursion_set_depth(depth) \
- do { \
- current->trace_recursion &= \
- ~(3 << TRACE_GRAPH_DEPTH_START_BIT); \
- current->trace_recursion |= \
- ((depth) & 3) << TRACE_GRAPH_DEPTH_START_BIT; \
- } while (0)
-
#define TRACE_CONTEXT_BITS 4
#define TRACE_FTRACE_START TRACE_FTRACE_BIT
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 3b9266aeb43b..e3f452eda0e3 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -896,8 +896,38 @@ extern void free_fgraph_ops(struct trace_array *tr);
enum {
TRACE_GRAPH_FL = 1,
+
+ /*
+ * In the very unlikely case that an interrupt came in
+ * at a start of graph tracing, and we want to trace
+ * the function in that interrupt, the depth can be greater
+ * than zero, because of the preempted start of a previous
+ * trace. In an even more unlikely case, depth could be 2
+ * if a softirq interrupted the start of graph tracing,
+ * followed by an interrupt preempting a start of graph
+ * tracing in the softirq, and depth can even be 3
+ * if an NMI came in at the start of an interrupt function
+ * that preempted a softirq start of a function that
+ * preempted normal context!!!! Luckily, it can't be
+ * greater than 3, so the next two bits are a mask
+ * of what the depth is when we set TRACE_GRAPH_FL
+ */
+
+ TRACE_GRAPH_DEPTH_START_BIT,
+ TRACE_GRAPH_DEPTH_END_BIT,
};
+static inline unsigned long ftrace_graph_depth(unsigned long *task_var)
+{
+ return (*task_var >> TRACE_GRAPH_DEPTH_START_BIT) & 3;
+}
+
+static inline void ftrace_graph_set_depth(unsigned long *task_var, int depth)
+{
+ *task_var &= ~(3 << TRACE_GRAPH_DEPTH_START_BIT);
+ *task_var |= (depth & 3) << TRACE_GRAPH_DEPTH_START_BIT;
+}
+
#ifdef CONFIG_DYNAMIC_FTRACE
extern struct ftrace_hash __rcu *ftrace_graph_hash;
extern struct ftrace_hash __rcu *ftrace_graph_notrace_hash;
@@ -930,7 +960,7 @@ ftrace_graph_addr(unsigned long *task_var, struct ftrace_graph_ent *trace)
* when the depth is zero.
*/
*task_var |= TRACE_GRAPH_FL;
- trace_recursion_set_depth(trace->depth);
+ ftrace_graph_set_depth(task_var, trace->depth);
/*
* If no irqs are to be traced, but a set_graph_function
@@ -955,7 +985,7 @@ ftrace_graph_addr_finish(struct fgraph_ops *gops, struct ftrace_graph_ret *trace
unsigned long *task_var = fgraph_get_task_var(gops);
if ((*task_var & TRACE_GRAPH_FL) &&
- trace->depth == trace_recursion_depth())
+ trace->depth == ftrace_graph_depth(task_var))
*task_var &= ~TRACE_GRAPH_FL;
}
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 16/34] function_graph: Move graph notrace bit to shadow stack global var
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (14 preceding siblings ...)
2023-12-18 13:14 ` [PATCH v5 15/34] function_graph: Move graph depth stored data " Masami Hiramatsu (Google)
@ 2023-12-18 13:14 ` Masami Hiramatsu (Google)
2023-12-18 13:15 ` [PATCH v5 17/34] function_graph: Implement fgraph_reserve_data() and fgraph_retrieve_data() Masami Hiramatsu (Google)
` (17 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:14 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
The use of the task->trace_recursion for the logic used for the function
graph no-trace was a bit of an abuse of that variable. Now that there
exists global vars that are per stack for registered graph traces, use
that instead.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v2:
- Make description lines shorter than 76 chars.
---
include/linux/trace_recursion.h | 7 -------
kernel/trace/trace.h | 9 +++++++++
kernel/trace/trace_functions_graph.c | 10 ++++++----
3 files changed, 15 insertions(+), 11 deletions(-)
diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h
index 00e792bf148d..cc11b0e9d220 100644
--- a/include/linux/trace_recursion.h
+++ b/include/linux/trace_recursion.h
@@ -44,13 +44,6 @@ enum {
*/
TRACE_IRQ_BIT,
- /*
- * To implement set_graph_notrace, if this bit is set, we ignore
- * function graph tracing of called functions, until the return
- * function is called to clear it.
- */
- TRACE_GRAPH_NOTRACE_BIT,
-
/* Used to prevent recursion recording from recursing. */
TRACE_RECORD_RECURSION_BIT,
};
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index e3f452eda0e3..fac29f08d5d8 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -915,8 +915,17 @@ enum {
TRACE_GRAPH_DEPTH_START_BIT,
TRACE_GRAPH_DEPTH_END_BIT,
+
+ /*
+ * To implement set_graph_notrace, if this bit is set, we ignore
+ * function graph tracing of called functions, until the return
+ * function is called to clear it.
+ */
+ TRACE_GRAPH_NOTRACE_BIT,
};
+#define TRACE_GRAPH_NOTRACE (1 << TRACE_GRAPH_NOTRACE_BIT)
+
static inline unsigned long ftrace_graph_depth(unsigned long *task_var)
{
return (*task_var >> TRACE_GRAPH_DEPTH_START_BIT) & 3;
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 66cce73e94f8..13d0387ac6a6 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -130,6 +130,7 @@ static inline int ftrace_graph_ignore_irqs(void)
int trace_graph_entry(struct ftrace_graph_ent *trace,
struct fgraph_ops *gops)
{
+ unsigned long *task_var = fgraph_get_task_var(gops);
struct trace_array *tr = gops->private;
struct trace_array_cpu *data;
unsigned long flags;
@@ -138,7 +139,7 @@ int trace_graph_entry(struct ftrace_graph_ent *trace,
int ret;
int cpu;
- if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT))
+ if (*task_var & TRACE_GRAPH_NOTRACE)
return 0;
/*
@@ -149,7 +150,7 @@ int trace_graph_entry(struct ftrace_graph_ent *trace,
* returning from the function.
*/
if (ftrace_graph_notrace_addr(trace->func)) {
- trace_recursion_set(TRACE_GRAPH_NOTRACE_BIT);
+ *task_var |= TRACE_GRAPH_NOTRACE_BIT;
/*
* Need to return 1 to have the return called
* that will clear the NOTRACE bit.
@@ -240,6 +241,7 @@ void __trace_graph_return(struct trace_array *tr,
void trace_graph_return(struct ftrace_graph_ret *trace,
struct fgraph_ops *gops)
{
+ unsigned long *task_var = fgraph_get_task_var(gops);
struct trace_array *tr = gops->private;
struct trace_array_cpu *data;
unsigned long flags;
@@ -249,8 +251,8 @@ void trace_graph_return(struct ftrace_graph_ret *trace,
ftrace_graph_addr_finish(gops, trace);
- if (trace_recursion_test(TRACE_GRAPH_NOTRACE_BIT)) {
- trace_recursion_clear(TRACE_GRAPH_NOTRACE_BIT);
+ if (*task_var & TRACE_GRAPH_NOTRACE) {
+ *task_var &= ~TRACE_GRAPH_NOTRACE;
return;
}
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 17/34] function_graph: Implement fgraph_reserve_data() and fgraph_retrieve_data()
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (15 preceding siblings ...)
2023-12-18 13:14 ` [PATCH v5 16/34] function_graph: Move graph notrace bit " Masami Hiramatsu (Google)
@ 2023-12-18 13:15 ` Masami Hiramatsu (Google)
2023-12-18 13:15 ` [PATCH v5 18/34] function_graph: Add selftest for passing local variables Masami Hiramatsu (Google)
` (16 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:15 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
Added functions that can be called by a fgraph_ops entryfunc and retfunc to
store state between the entry of the function being traced to the exit of
the same function. The fgraph_ops entryfunc() may call
fgraph_reserve_data() to store up to 32 words onto the task's shadow
ret_stack and this then can be retrieved by fgraph_retrieve_data() called
by the corresponding retfunc().
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Store fgraph_array index to the data entry.
- Both function requires fgraph_array index to store/retrieve data.
- Reserve correct size of the data.
- Return correct data area.
Changes in v2:
- Retrieve the reserved size by fgraph_retrieve_data().
- Expand the maximum data size to 32 words.
- Update stack index with __get_index(val) if FGRAPH_TYPE_ARRAY entry.
- fix typos and make description lines shorter than 76 chars.
---
include/linux/ftrace.h | 3 +
kernel/trace/fgraph.c | 175 ++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 170 insertions(+), 8 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 09ca4bba63f2..1c121237016e 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1075,6 +1075,9 @@ struct fgraph_ops {
int idx;
};
+void *fgraph_reserve_data(int idx, int size_bytes);
+void *fgraph_retrieve_data(int idx, int *size_bytes);
+
/*
* Stack of return addresses for functions
* of a thread.
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 6e52c4989ef3..07385d53cc1b 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -41,17 +41,29 @@
* bits: 10 - 11 Type of storage
* 0 - reserved
* 1 - bitmap of fgraph_array index
+ * 2 - reserved data
*
* For bitmap of fgraph_array index
* bits: 12 - 27 The bitmap of fgraph_ops fgraph_array index
*
+ * For reserved data:
+ * bits: 12 - 17 The size in words that is stored
+ * bits: 18 - 23 The index of fgraph_array, which shows who is stored
+ *
* That is, at the end of function_graph_enter, if the first and forth
* fgraph_ops on the fgraph_array[] (index 0 and 3) needs their retfunc called
- * on the return of the function being traced, this is what will be on the
- * task's shadow ret_stack: (the stack grows upward)
+ * on the return of the function being traced, and the forth fgraph_ops
+ * stored two words of data, this is what will be on the task's shadow
+ * ret_stack: (the stack grows upward)
*
* | | <- task->curr_ret_stack
* +--------------------------------------------+
+ * | data_type(idx:3, size:2, |
+ * | offset:FGRAPH_RET_INDEX+3) | ( Data with size of 2 words)
+ * +--------------------------------------------+ ( It is 4 words from the ret_stack)
+ * | STORED DATA WORD 2 |
+ * | STORED DATA WORD 1 |
+ * +------i-------------------------------------+
* | bitmap_type(bitmap:(BIT(3)|BIT(0)), |
* | offset:FGRAPH_RET_INDEX) | <- the offset is from here
* +--------------------------------------------+
@@ -78,14 +90,23 @@
enum {
FGRAPH_TYPE_RESERVED = 0,
FGRAPH_TYPE_BITMAP = 1,
+ FGRAPH_TYPE_DATA = 2,
};
#define FGRAPH_INDEX_SIZE 16
#define FGRAPH_INDEX_MASK GENMASK(FGRAPH_INDEX_SIZE - 1, 0)
#define FGRAPH_INDEX_SHIFT (FGRAPH_TYPE_SHIFT + FGRAPH_TYPE_SIZE)
-/* Currently the max stack index can't be more than register callers */
-#define FGRAPH_MAX_INDEX (FGRAPH_INDEX_SIZE + FGRAPH_RET_INDEX)
+#define FGRAPH_DATA_SIZE 5
+#define FGRAPH_DATA_MASK ((1 << FGRAPH_DATA_SIZE) - 1)
+#define FGRAPH_DATA_SHIFT (FGRAPH_TYPE_SHIFT + FGRAPH_TYPE_SIZE)
+
+#define FGRAPH_DATA_INDEX_SIZE 4
+#define FGRAPH_DATA_INDEX_MASK ((1 << FGRAPH_DATA_INDEX_SIZE) - 1)
+#define FGRAPH_DATA_INDEX_SHIFT (FGRAPH_DATA_SHIFT + FGRAPH_DATA_SIZE)
+
+#define FGRAPH_MAX_INDEX \
+ ((FGRAPH_INDEX_SIZE << FGRAPH_DATA_SIZE) + FGRAPH_RET_INDEX)
#define FGRAPH_ARRAY_SIZE FGRAPH_INDEX_SIZE
@@ -97,6 +118,8 @@ enum {
#define RET_STACK(t, index) ((struct ftrace_ret_stack *)(&(t)->ret_stack[index]))
+#define FGRAPH_MAX_DATA_SIZE (sizeof(long) * (1 << FGRAPH_DATA_SIZE))
+
/*
* Each fgraph_ops has a reservered unsigned long at the end (top) of the
* ret_stack to store task specific state.
@@ -145,14 +168,39 @@ static int fgraph_lru_alloc_index(void)
return idx;
}
+static inline int __get_index(unsigned long val)
+{
+ return val & FGRAPH_RET_INDEX_MASK;
+}
+
+static inline int __get_type(unsigned long val)
+{
+ return (val >> FGRAPH_TYPE_SHIFT) & FGRAPH_TYPE_MASK;
+}
+
+static inline int __get_data_index(unsigned long val)
+{
+ return (val >> FGRAPH_DATA_INDEX_SHIFT) & FGRAPH_DATA_INDEX_MASK;
+}
+
+static inline int __get_data_size(unsigned long val)
+{
+ return (val >> FGRAPH_DATA_SHIFT) & FGRAPH_DATA_MASK;
+}
+
+static inline unsigned long get_fgraph_entry(struct task_struct *t, int index)
+{
+ return t->ret_stack[index];
+}
+
static inline int get_ret_stack_index(struct task_struct *t, int offset)
{
- return t->ret_stack[offset] & FGRAPH_RET_INDEX_MASK;
+ return __get_index(t->ret_stack[offset]);
}
static inline int get_fgraph_type(struct task_struct *t, int offset)
{
- return (t->ret_stack[offset] >> FGRAPH_TYPE_SHIFT) & FGRAPH_TYPE_MASK;
+ return __get_type(t->ret_stack[offset]);
}
static inline unsigned long
@@ -179,6 +227,22 @@ add_fgraph_index_bitmap(struct task_struct *t, int offset, unsigned long bitmap)
t->ret_stack[offset] |= (bitmap << FGRAPH_INDEX_SHIFT);
}
+static inline void *get_fgraph_data(struct task_struct *t, int index)
+{
+ unsigned long val = t->ret_stack[index];
+
+ if (__get_type(val) != FGRAPH_TYPE_DATA)
+ return NULL;
+ index -= __get_data_size(val);
+ return (void *)&t->ret_stack[index];
+}
+
+static inline unsigned long make_fgraph_data(int idx, int size, int offset)
+{
+ return (idx << FGRAPH_DATA_INDEX_SHIFT) | (size << FGRAPH_DATA_SHIFT) |
+ (FGRAPH_TYPE_DATA << FGRAPH_TYPE_SHIFT) | offset;
+}
+
/* ftrace_graph_entry set to this to tell some archs to run function graph */
static int entry_run(struct ftrace_graph_ent *trace, struct fgraph_ops *ops)
{
@@ -212,6 +276,92 @@ static void ret_stack_init_task_vars(unsigned long *ret_stack)
memset(gvals, 0, sizeof(*gvals) * FGRAPH_ARRAY_SIZE);
}
+/**
+ * fgraph_reserve_data - Reserve storage on the task's ret_stack
+ * @idx: The index of fgraph_array
+ * @size_bytes: The size in bytes to reserve
+ *
+ * Reserves space of up to FGRAPH_MAX_DATA_SIZE bytes on the
+ * task's ret_stack shadow stack, for a given fgraph_ops during
+ * the entryfunc() call. If entryfunc() returns zero, the storage
+ * is discarded. An entryfunc() can only call this once per iteration.
+ * The fgraph_ops retfunc() can retrieve this stored data with
+ * fgraph_retrieve_data().
+ *
+ * Returns: On success, a pointer to the data on the stack.
+ * Otherwise, NULL if there's not enough space left on the
+ * ret_stack for the data, or if fgraph_reserve_data() was called
+ * more than once for a single entryfunc() call.
+ */
+void *fgraph_reserve_data(int idx, int size_bytes)
+{
+ unsigned long val;
+ void *data;
+ int curr_ret_stack = current->curr_ret_stack;
+ int data_size;
+
+ if (size_bytes > FGRAPH_MAX_DATA_SIZE)
+ return NULL;
+
+ /* Convert to number of longs + data word */
+ data_size = DIV_ROUND_UP(size_bytes, sizeof(long));
+
+ val = get_fgraph_entry(current, curr_ret_stack - 1);
+ data = ¤t->ret_stack[curr_ret_stack];
+
+ curr_ret_stack += data_size + 1;
+ if (unlikely(curr_ret_stack >= SHADOW_STACK_MAX_INDEX))
+ return NULL;
+
+ val = make_fgraph_data(idx, data_size, __get_index(val) + data_size + 1);
+
+ /* Set the last word to be reserved */
+ current->ret_stack[curr_ret_stack - 1] = val;
+
+ /* Make sure interrupts see this */
+ barrier();
+ current->curr_ret_stack = curr_ret_stack;
+ /* Again sync with interrupts, and reset reserve */
+ current->ret_stack[curr_ret_stack - 1] = val;
+
+ return data;
+}
+
+/**
+ * fgraph_retrieve_data - Retrieve stored data from fgraph_reserve_data()
+ * @idx: the index of fgraph_array (fgraph_ops::idx)
+ * @size_bytes: pointer to retrieved data size.
+ *
+ * This is to be called by a fgraph_ops retfunc(), to retrieve data that
+ * was stored by the fgraph_ops entryfunc() on the function entry.
+ * That is, this will retrieve the data that was reserved on the
+ * entry of the function that corresponds to the exit of the function
+ * that the fgraph_ops retfunc() is called on.
+ *
+ * Returns: The stored data from fgraph_reserve_data() called by the
+ * matching entryfunc() for the retfunc() this is called from.
+ * Or NULL if there was nothing stored.
+ */
+void *fgraph_retrieve_data(int idx, int *size_bytes)
+{
+ int index = current->curr_ret_stack - 1;
+ unsigned long val;
+
+ val = get_fgraph_entry(current, index);
+ while (__get_type(val) == FGRAPH_TYPE_DATA) {
+ if (__get_data_index(val) == idx)
+ goto found;
+ index -= __get_data_size(val) + 1;
+ val = get_fgraph_entry(current, index);
+ }
+ return NULL;
+found:
+ if (size_bytes)
+ *size_bytes = __get_data_size(val) *
+ sizeof(long);
+ return get_fgraph_data(current, index);
+}
+
/**
* fgraph_get_task_var - retrieve a task specific state variable
* @gops: The ftrace_ops that owns the task specific variable
@@ -449,13 +599,18 @@ int function_graph_enter(unsigned long ret, unsigned long func,
for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) {
struct fgraph_ops *gops = fgraph_array[i];
+ int save_curr_ret_stack;
if (gops == &fgraph_stub)
continue;
+ save_curr_ret_stack = current->curr_ret_stack;
if (ftrace_ops_test(&gops->ops, func, NULL) &&
gops->entryfunc(&trace, gops))
bitmap |= BIT(i);
+ else
+ /* Clear out any saved storage */
+ current->curr_ret_stack = save_curr_ret_stack;
}
if (!bitmap)
@@ -481,6 +636,7 @@ int function_graph_enter_ops(unsigned long ret, unsigned long func,
struct fgraph_ops *gops)
{
struct ftrace_graph_ent trace;
+ int save_curr_ret_stack;
int index;
int type;
@@ -497,13 +653,15 @@ int function_graph_enter_ops(unsigned long ret, unsigned long func,
trace.func = func;
trace.depth = current->curr_ret_depth;
+ save_curr_ret_stack = current->curr_ret_stack;
if (gops->entryfunc(&trace, gops)) {
if (type == FGRAPH_TYPE_RESERVED)
set_fgraph_index_bitmap(current, index, BIT(gops->idx));
else
add_fgraph_index_bitmap(current, index, BIT(gops->idx));
return 0;
- }
+ } else
+ current->curr_ret_stack = save_curr_ret_stack;
if (type == FGRAPH_TYPE_RESERVED) {
current->curr_ret_stack -= FGRAPH_RET_INDEX + 1;
@@ -648,7 +806,8 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
* curr_ret_stack is after that.
*/
barrier();
- current->curr_ret_stack -= FGRAPH_RET_INDEX + 1;
+ current->curr_ret_stack = index - FGRAPH_RET_INDEX;
+
current->curr_ret_depth--;
return ret;
}
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 18/34] function_graph: Add selftest for passing local variables
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (16 preceding siblings ...)
2023-12-18 13:15 ` [PATCH v5 17/34] function_graph: Implement fgraph_reserve_data() and fgraph_retrieve_data() Masami Hiramatsu (Google)
@ 2023-12-18 13:15 ` Masami Hiramatsu (Google)
2023-12-18 13:15 ` [PATCH v5 19/34] function_graph: Add a new entry handler with parent_ip and ftrace_regs Masami Hiramatsu (Google)
` (15 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:15 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Steven Rostedt (VMware) <rostedt@goodmis.org>
Add boot up selftest that passes variables from a function entry to a
function exit, and make sure that they do get passed around.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v2:
- Add reserved size test.
- Use pr_*() instead of printk(KERN_*).
---
kernel/trace/trace_selftest.c | 169 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 169 insertions(+)
diff --git a/kernel/trace/trace_selftest.c b/kernel/trace/trace_selftest.c
index f0758afa2f7d..4d86cd4c8c8c 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -756,6 +756,173 @@ trace_selftest_startup_function(struct tracer *trace, struct trace_array *tr)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+#define BYTE_NUMBER 123
+#define SHORT_NUMBER 12345
+#define WORD_NUMBER 1234567890
+#define LONG_NUMBER 1234567890123456789LL
+
+static int fgraph_store_size __initdata;
+static const char *fgraph_store_type_name __initdata;
+static char *fgraph_error_str __initdata;
+static char fgraph_error_str_buf[128] __initdata;
+
+static __init int store_entry(struct ftrace_graph_ent *trace,
+ struct fgraph_ops *gops)
+{
+ const char *type = fgraph_store_type_name;
+ int size = fgraph_store_size;
+ void *p;
+
+ p = fgraph_reserve_data(gops->idx, size);
+ if (!p) {
+ snprintf(fgraph_error_str_buf, sizeof(fgraph_error_str_buf),
+ "Failed to reserve %s\n", type);
+ fgraph_error_str = fgraph_error_str_buf;
+ return 0;
+ }
+
+ switch (fgraph_store_size) {
+ case 1:
+ *(char *)p = BYTE_NUMBER;
+ break;
+ case 2:
+ *(short *)p = SHORT_NUMBER;
+ break;
+ case 4:
+ *(int *)p = WORD_NUMBER;
+ break;
+ case 8:
+ *(long long *)p = LONG_NUMBER;
+ break;
+ }
+
+ return 1;
+}
+
+static __init void store_return(struct ftrace_graph_ret *trace,
+ struct fgraph_ops *gops)
+{
+ const char *type = fgraph_store_type_name;
+ long long expect = 0;
+ long long found = -1;
+ int size;
+ char *p;
+
+ p = fgraph_retrieve_data(gops->idx, &size);
+ if (!p) {
+ snprintf(fgraph_error_str_buf, sizeof(fgraph_error_str_buf),
+ "Failed to retrieve %s\n", type);
+ fgraph_error_str = fgraph_error_str_buf;
+ return;
+ }
+ if (fgraph_store_size > size) {
+ snprintf(fgraph_error_str_buf, sizeof(fgraph_error_str_buf),
+ "Retrieved size %d is smaller than expected %d\n",
+ size, (int)fgraph_store_size);
+ fgraph_error_str = fgraph_error_str_buf;
+ return;
+ }
+
+ switch (fgraph_store_size) {
+ case 1:
+ expect = BYTE_NUMBER;
+ found = *(char *)p;
+ break;
+ case 2:
+ expect = SHORT_NUMBER;
+ found = *(short *)p;
+ break;
+ case 4:
+ expect = WORD_NUMBER;
+ found = *(int *)p;
+ break;
+ case 8:
+ expect = LONG_NUMBER;
+ found = *(long long *)p;
+ break;
+ }
+
+ if (found != expect) {
+ snprintf(fgraph_error_str_buf, sizeof(fgraph_error_str_buf),
+ "%s returned not %lld but %lld\n", type, expect, found);
+ fgraph_error_str = fgraph_error_str_buf;
+ return;
+ }
+ fgraph_error_str = NULL;
+}
+
+static struct fgraph_ops store_bytes __initdata = {
+ .entryfunc = store_entry,
+ .retfunc = store_return,
+};
+
+static int __init test_graph_storage_type(const char *name, int size)
+{
+ char *func_name;
+ int len;
+ int ret;
+
+ fgraph_store_type_name = name;
+ fgraph_store_size = size;
+
+ snprintf(fgraph_error_str_buf, sizeof(fgraph_error_str_buf),
+ "Failed to execute storage %s\n", name);
+ fgraph_error_str = fgraph_error_str_buf;
+
+ pr_cont("PASSED\n");
+ pr_info("Testing fgraph storage of %d byte%s: ", size, size > 1 ? "s" : "");
+
+ func_name = "*" __stringify(DYN_FTRACE_TEST_NAME);
+ len = strlen(func_name);
+
+ ret = ftrace_set_filter(&store_bytes.ops, func_name, len, 1);
+ if (ret && ret != -ENODEV) {
+ pr_cont("*Could not set filter* ");
+ return -1;
+ }
+
+ ret = register_ftrace_graph(&store_bytes);
+ if (ret) {
+ pr_warn("Failed to init store_bytes fgraph tracing\n");
+ return -1;
+ }
+
+ DYN_FTRACE_TEST_NAME();
+
+ unregister_ftrace_graph(&store_bytes);
+
+ if (fgraph_error_str) {
+ pr_cont("*** %s ***", fgraph_error_str);
+ return -1;
+ }
+
+ return 0;
+}
+/* Test the storage passed across function_graph entry and return */
+static __init int test_graph_storage(void)
+{
+ int ret;
+
+ ret = test_graph_storage_type("byte", 1);
+ if (ret)
+ return ret;
+ ret = test_graph_storage_type("short", 2);
+ if (ret)
+ return ret;
+ ret = test_graph_storage_type("word", 4);
+ if (ret)
+ return ret;
+ ret = test_graph_storage_type("long long", 8);
+ if (ret)
+ return ret;
+ return 0;
+}
+#else
+static inline int test_graph_storage(void) { return 0; }
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
/* Maximum number of functions to trace before diagnosing a hang */
#define GRAPH_MAX_FUNC_TEST 100000000
@@ -913,6 +1080,8 @@ trace_selftest_startup_function_graph(struct tracer *trace,
ftrace_set_global_filter(NULL, 0, 1);
#endif
+ ret = test_graph_storage();
+
/* Don't test dynamic tracing, the function tracer already did */
out:
/* Stop it if we failed */
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 19/34] function_graph: Add a new entry handler with parent_ip and ftrace_regs
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (17 preceding siblings ...)
2023-12-18 13:15 ` [PATCH v5 18/34] function_graph: Add selftest for passing local variables Masami Hiramatsu (Google)
@ 2023-12-18 13:15 ` Masami Hiramatsu (Google)
2023-12-18 13:15 ` [PATCH v5 20/34] function_graph: Add a new exit " Masami Hiramatsu (Google)
` (14 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:15 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Add a new entry handler to fgraph_ops as 'entryregfunc' which takes
parent_ip and ftrace_regs. Note that the 'entryfunc' and 'entryregfunc'
are mutual exclusive. You can set only one of them.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Update for new multiple fgraph.
---
arch/arm64/kernel/ftrace.c | 2 +
arch/loongarch/kernel/ftrace_dyn.c | 6 ++++
arch/powerpc/kernel/trace/ftrace.c | 2 +
arch/powerpc/kernel/trace/ftrace_64_pg.c | 10 ++++---
arch/x86/kernel/ftrace.c | 42 ++++++++++++++++--------------
include/linux/ftrace.h | 19 +++++++++++---
kernel/trace/fgraph.c | 30 +++++++++++++++++----
7 files changed, 76 insertions(+), 35 deletions(-)
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index 205937e04ece..9d71a475d4c5 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -495,7 +495,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
if (bit < 0)
return;
- if (!function_graph_enter_ops(*parent, ip, fregs->fp, parent, gops))
+ if (!function_graph_enter_ops(*parent, ip, fregs->fp, parent, fregs, gops))
*parent = (unsigned long)&return_to_handler;
ftrace_test_recursion_unlock(bit);
diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c
index 73858c9029cc..39b3f09a5e0c 100644
--- a/arch/loongarch/kernel/ftrace_dyn.c
+++ b/arch/loongarch/kernel/ftrace_dyn.c
@@ -244,7 +244,11 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct pt_regs *regs = &fregs->regs;
unsigned long *parent = (unsigned long *)®s->regs[1];
- prepare_ftrace_return(ip, (unsigned long *)parent);
+ if (unlikely(atomic_read(¤t->tracing_graph_pause)))
+ return;
+
+ if (!function_graph_enter_regs(regs->regs[1], ip, 0, parent, fregs))
+ regs->regs[1] = (unsigned long)&return_to_handler;
}
#else
static int ftrace_modify_graph_caller(bool enable)
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index 82010629cf88..9bf1b6912116 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -422,7 +422,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
if (bit < 0)
goto out;
- if (!function_graph_enter(parent_ip, ip, 0, (unsigned long *)sp))
+ if (!function_graph_enter_regs(parent_ip, ip, 0, (unsigned long *)sp, fregs))
parent_ip = ppc_function_entry(return_to_handler);
ftrace_test_recursion_unlock(bit);
diff --git a/arch/powerpc/kernel/trace/ftrace_64_pg.c b/arch/powerpc/kernel/trace/ftrace_64_pg.c
index 7b85c3b460a3..43f6cfaaf7db 100644
--- a/arch/powerpc/kernel/trace/ftrace_64_pg.c
+++ b/arch/powerpc/kernel/trace/ftrace_64_pg.c
@@ -795,7 +795,8 @@ int ftrace_disable_ftrace_graph_caller(void)
* in current thread info. Return the address we want to divert to.
*/
static unsigned long
-__prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp)
+__prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp,
+ struct ftrace_regs *fregs)
{
unsigned long return_hooker;
int bit;
@@ -812,7 +813,7 @@ __prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp
return_hooker = ppc_function_entry(return_to_handler);
- if (!function_graph_enter(parent, ip, 0, (unsigned long *)sp))
+ if (!function_graph_enter_regs(parent, ip, 0, (unsigned long *)sp, fregs))
parent = return_hooker;
ftrace_test_recursion_unlock(bit);
@@ -824,13 +825,14 @@ __prepare_ftrace_return(unsigned long parent, unsigned long ip, unsigned long sp
void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs)
{
- fregs->regs.link = __prepare_ftrace_return(parent_ip, ip, fregs->regs.gpr[1]);
+ fregs->regs.link = __prepare_ftrace_return(parent_ip, ip,
+ fregs->regs.gpr[1], fregs);
}
#else
unsigned long prepare_ftrace_return(unsigned long parent, unsigned long ip,
unsigned long sp)
{
- return __prepare_ftrace_return(parent, ip, sp);
+ return __prepare_ftrace_return(parent, ip, sp, NULL);
}
#endif
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 845e29b4254f..0f757e399a96 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -614,16 +614,8 @@ int ftrace_disable_ftrace_graph_caller(void)
}
#endif /* CONFIG_DYNAMIC_FTRACE && !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
-/*
- * Hook the return address and push it in the stack of return addrs
- * in current thread info.
- */
-void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
- unsigned long frame_pointer)
+static inline bool skip_ftrace_return(void)
{
- unsigned long return_hooker = (unsigned long)&return_to_handler;
- int bit;
-
/*
* When resuming from suspend-to-ram, this function can be indirectly
* called from early CPU startup code while the CPU is in real mode,
@@ -633,13 +625,28 @@ void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
* This check isn't as accurate as virt_addr_valid(), but it should be
* good enough for this purpose, and it's fast.
*/
- if (unlikely((long)__builtin_frame_address(0) >= 0))
- return;
+ if ((long)__builtin_frame_address(0) >= 0)
+ return true;
- if (unlikely(ftrace_graph_is_dead()))
- return;
+ if (ftrace_graph_is_dead())
+ return true;
+
+ if (atomic_read(¤t->tracing_graph_pause))
+ return true;
+ return false;
+}
- if (unlikely(atomic_read(¤t->tracing_graph_pause)))
+/*
+ * Hook the return address and push it in the stack of return addrs
+ * in current thread info.
+ */
+void prepare_ftrace_return(unsigned long ip, unsigned long *parent,
+ unsigned long frame_pointer)
+{
+ unsigned long return_hooker = (unsigned long)&return_to_handler;
+ int bit;
+
+ if (unlikely(skip_ftrace_return()))
return;
bit = ftrace_test_recursion_trylock(ip, *parent);
@@ -661,17 +668,14 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
struct fgraph_ops *gops = container_of(op, struct fgraph_ops, ops);
int bit;
- if (unlikely(ftrace_graph_is_dead()))
- return;
-
- if (unlikely(atomic_read(¤t->tracing_graph_pause)))
+ if (unlikely(skip_ftrace_return()))
return;
bit = ftrace_test_recursion_trylock(ip, *parent);
if (bit < 0)
return;
- if (!function_graph_enter_ops(*parent, ip, 0, parent, gops))
+ if (!function_graph_enter_ops(*parent, ip, 0, parent, fregs, gops))
*parent = (unsigned long)&return_to_handler;
ftrace_test_recursion_unlock(bit);
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 1c121237016e..6da6cc9aaeaf 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1063,6 +1063,11 @@ typedef void (*trace_func_graph_ret_t)(struct ftrace_graph_ret *,
typedef int (*trace_func_graph_ent_t)(struct ftrace_graph_ent *,
struct fgraph_ops *); /* entry */
+typedef int (*trace_func_graph_regs_ent_t)(unsigned long func,
+ unsigned long parent_ip,
+ struct ftrace_regs *fregs,
+ struct fgraph_ops *); /* entry w/ regs */
+
extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
@@ -1070,6 +1075,7 @@ extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph
struct fgraph_ops {
trace_func_graph_ent_t entryfunc;
trace_func_graph_ret_t retfunc;
+ trace_func_graph_regs_ent_t entryregfunc;
struct ftrace_ops ops; /* for the hash lists */
void *private;
int idx;
@@ -1106,13 +1112,20 @@ struct ftrace_ret_stack {
extern void return_to_handler(void);
extern int
-function_graph_enter(unsigned long ret, unsigned long func,
- unsigned long frame_pointer, unsigned long *retp);
+function_graph_enter_regs(unsigned long ret, unsigned long func,
+ unsigned long frame_pointer, unsigned long *retp,
+ struct ftrace_regs *fregs);
+
+static inline int function_graph_enter(unsigned long ret, unsigned long func,
+ unsigned long fp, unsigned long *retp)
+{
+ return function_graph_enter_regs(ret, func, fp, retp, NULL);
+}
extern int
function_graph_enter_ops(unsigned long ret, unsigned long func,
unsigned long frame_pointer, unsigned long *retp,
- struct fgraph_ops *gops);
+ struct ftrace_regs *fregs, struct fgraph_ops *gops);
struct ftrace_ret_stack *
ftrace_graph_get_ret_stack(struct task_struct *task, int idx);
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 07385d53cc1b..52fb63f8251c 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -569,9 +569,21 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
# define MCOUNT_INSN_SIZE 0
#endif
+static inline int call_entry_func(struct ftrace_graph_ent *trace,
+ unsigned long func, unsigned long ret,
+ struct ftrace_regs *fregs,
+ struct fgraph_ops *gops)
+{
+ if (gops->entryregfunc)
+ return gops->entryregfunc(func, ret, fregs, gops);
+
+ return gops->entryfunc(trace, gops);
+}
+
/* If the caller does not use ftrace, call this function. */
-int function_graph_enter(unsigned long ret, unsigned long func,
- unsigned long frame_pointer, unsigned long *retp)
+int function_graph_enter_regs(unsigned long ret, unsigned long func,
+ unsigned long frame_pointer, unsigned long *retp,
+ struct ftrace_regs *fregs)
{
struct ftrace_graph_ent trace;
unsigned long bitmap = 0;
@@ -606,7 +618,7 @@ int function_graph_enter(unsigned long ret, unsigned long func,
save_curr_ret_stack = current->curr_ret_stack;
if (ftrace_ops_test(&gops->ops, func, NULL) &&
- gops->entryfunc(&trace, gops))
+ call_entry_func(&trace, func, ret, fregs, gops))
bitmap |= BIT(i);
else
/* Clear out any saved storage */
@@ -633,6 +645,7 @@ int function_graph_enter(unsigned long ret, unsigned long func,
/* This is called from ftrace_graph_func() via ftrace */
int function_graph_enter_ops(unsigned long ret, unsigned long func,
unsigned long frame_pointer, unsigned long *retp,
+ struct ftrace_regs *fregs,
struct fgraph_ops *gops)
{
struct ftrace_graph_ent trace;
@@ -654,7 +667,7 @@ int function_graph_enter_ops(unsigned long ret, unsigned long func,
trace.func = func;
trace.depth = current->curr_ret_depth;
save_curr_ret_stack = current->curr_ret_stack;
- if (gops->entryfunc(&trace, gops)) {
+ if (call_entry_func(&trace, func, ret, fregs, gops)) {
if (type == FGRAPH_TYPE_RESERVED)
set_fgraph_index_bitmap(current, index, BIT(gops->idx));
else
@@ -935,7 +948,8 @@ void fgraph_init_ops(struct ftrace_ops *dst_ops,
struct ftrace_ops *src_ops)
{
dst_ops->func = ftrace_graph_func;
- dst_ops->flags = FTRACE_OPS_FL_PID | FTRACE_OPS_GRAPH_STUB;
+ dst_ops->flags = FTRACE_OPS_FL_PID | FTRACE_OPS_GRAPH_STUB |
+ FTRACE_OPS_FL_SAVE_ARGS;
#ifdef FTRACE_GRAPH_TRAMP_ADDR
dst_ops->trampoline = FTRACE_GRAPH_TRAMP_ADDR;
@@ -1177,10 +1191,14 @@ int register_ftrace_graph(struct fgraph_ops *gops)
int ret = 0;
int i;
+ if (gops->entryfunc && gops->entryregfunc)
+ return -EINVAL;
+
mutex_lock(&ftrace_lock);
if (!gops->ops.func) {
- gops->ops.flags |= FTRACE_OPS_GRAPH_STUB;
+ gops->ops.flags |= FTRACE_OPS_GRAPH_STUB |
+ FTRACE_OPS_FL_SAVE_ARGS;
gops->ops.func = ftrace_graph_func;
#ifdef FTRACE_GRAPH_TRAMP_ADDR
gops->ops.trampoline = FTRACE_GRAPH_TRAMP_ADDR;
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 20/34] function_graph: Add a new exit handler with parent_ip and ftrace_regs
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (18 preceding siblings ...)
2023-12-18 13:15 ` [PATCH v5 19/34] function_graph: Add a new entry handler with parent_ip and ftrace_regs Masami Hiramatsu (Google)
@ 2023-12-18 13:15 ` Masami Hiramatsu (Google)
2023-12-18 13:15 ` [PATCH v5 21/34] x86/ftrace: Enable HAVE_FUNCTION_GRAPH_FREGS Masami Hiramatsu (Google)
` (13 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:15 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Add a new return handler to fgraph_ops as 'retregfunc' which takes
parent_ip and ftrace_regs instead of ftrace_graph_ret. This handler
is available only if the arch support CONFIG_HAVE_FUNCTION_GRAPH_FREGS.
Note that the 'retfunc' and 'reregfunc' are mutual exclusive.
You can set only one of them.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Update for new multiple fgraph.
- Save the return address to instruction pointer in ftrace_regs.
---
arch/x86/include/asm/ftrace.h | 2 +
include/linux/ftrace.h | 10 +++++-
kernel/trace/Kconfig | 5 ++-
kernel/trace/fgraph.c | 70 ++++++++++++++++++++++++++++-------------
4 files changed, 63 insertions(+), 24 deletions(-)
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 415cf7a2ec2c..0b306c82855d 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -72,6 +72,8 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs)
override_function_with_return(&(fregs)->regs)
#define ftrace_regs_query_register_offset(name) \
regs_query_register_offset(name)
+#define ftrace_regs_get_frame_pointer(fregs) \
+ frame_pointer(&(fregs)->regs)
struct ftrace_ops;
#define ftrace_graph_func ftrace_graph_func
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 6da6cc9aaeaf..79875a00c02b 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -43,7 +43,9 @@ struct dyn_ftrace;
char *arch_ftrace_match_adjust(char *str, const char *search);
-#ifdef CONFIG_HAVE_FUNCTION_GRAPH_RETVAL
+#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FREGS
+unsigned long ftrace_return_to_handler(struct ftrace_regs *fregs);
+#elif defined(CONFIG_HAVE_FUNCTION_GRAPH_RETVAL)
struct fgraph_ret_regs;
unsigned long ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs);
#else
@@ -157,6 +159,7 @@ struct ftrace_regs {
#define ftrace_regs_set_instruction_pointer(fregs, ip) do { } while (0)
#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
+
static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs)
{
if (!fregs)
@@ -1067,6 +1070,10 @@ typedef int (*trace_func_graph_regs_ent_t)(unsigned long func,
unsigned long parent_ip,
struct ftrace_regs *fregs,
struct fgraph_ops *); /* entry w/ regs */
+typedef void (*trace_func_graph_regs_ret_t)(unsigned long func,
+ unsigned long parent_ip,
+ struct ftrace_regs *,
+ struct fgraph_ops *); /* return w/ regs */
extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);
@@ -1076,6 +1083,7 @@ struct fgraph_ops {
trace_func_graph_ent_t entryfunc;
trace_func_graph_ret_t retfunc;
trace_func_graph_regs_ent_t entryregfunc;
+ trace_func_graph_regs_ret_t retregfunc;
struct ftrace_ops ops; /* for the hash lists */
void *private;
int idx;
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 61c541c36596..308b3bec01b1 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -34,6 +34,9 @@ config HAVE_FUNCTION_GRAPH_TRACER
config HAVE_FUNCTION_GRAPH_RETVAL
bool
+config HAVE_FUNCTION_GRAPH_FREGS
+ bool
+
config HAVE_DYNAMIC_FTRACE
bool
help
@@ -232,7 +235,7 @@ config FUNCTION_GRAPH_TRACER
config FUNCTION_GRAPH_RETVAL
bool "Kernel Function Graph Return Value"
- depends on HAVE_FUNCTION_GRAPH_RETVAL
+ depends on HAVE_FUNCTION_GRAPH_RETVAL || HAVE_FUNCTION_GRAPH_FREGS
depends on FUNCTION_GRAPH_TRACER
default n
help
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 52fb63f8251c..088432b695a6 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -685,8 +685,8 @@ int function_graph_enter_ops(unsigned long ret, unsigned long func,
/* Retrieve a function return address to the trace stack on thread info.*/
static struct ftrace_ret_stack *
-ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
- unsigned long frame_pointer, int *index)
+ftrace_pop_return_trace(unsigned long *ret, unsigned long frame_pointer,
+ int *index)
{
struct ftrace_ret_stack *ret_stack;
@@ -731,10 +731,6 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
*index += FGRAPH_RET_INDEX;
*ret = ret_stack->ret;
- trace->func = ret_stack->func;
- trace->calltime = ret_stack->calltime;
- trace->overrun = atomic_read(¤t->trace_overrun);
- trace->depth = current->curr_ret_depth;
/*
* We still want to trace interrupts coming in if
* max_depth is set to 1. Make sure the decrement is
@@ -773,21 +769,42 @@ static struct notifier_block ftrace_suspend_notifier = {
/* fgraph_ret_regs is not defined without CONFIG_FUNCTION_GRAPH_RETVAL */
struct fgraph_ret_regs;
+static void fgraph_call_retfunc(struct ftrace_regs *fregs,
+ struct fgraph_ret_regs *ret_regs,
+ struct ftrace_ret_stack *ret_stack,
+ struct fgraph_ops *gops)
+{
+ struct ftrace_graph_ret trace;
+
+ trace.func = ret_stack->func;
+ trace.calltime = ret_stack->calltime;
+ trace.overrun = atomic_read(¤t->trace_overrun);
+ trace.depth = current->curr_ret_depth;
+ trace.rettime = trace_clock_local();
+#ifdef CONFIG_FUNCTION_GRAPH_RETVAL
+ if (fregs)
+ trace.retval = ftrace_regs_return_value(fregs);
+ else
+ trace.retval = fgraph_ret_regs_return_value(ret_regs);
+#endif
+ gops->retfunc(&trace, gops);
+}
+
/*
* Send the trace to the ring-buffer.
* @return the original return address.
*/
-static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs,
+static unsigned long __ftrace_return_to_handler(struct ftrace_regs *fregs,
+ struct fgraph_ret_regs *ret_regs,
unsigned long frame_pointer)
{
struct ftrace_ret_stack *ret_stack;
- struct ftrace_graph_ret trace;
unsigned long bitmap;
unsigned long ret;
int index;
int i;
- ret_stack = ftrace_pop_return_trace(&trace, &ret, frame_pointer, &index);
+ ret_stack = ftrace_pop_return_trace(&ret, frame_pointer, &index);
if (unlikely(!ret_stack)) {
ftrace_graph_stop();
@@ -796,10 +813,8 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
return (unsigned long)panic;
}
- trace.rettime = trace_clock_local();
-#ifdef CONFIG_FUNCTION_GRAPH_RETVAL
- trace.retval = fgraph_ret_regs_return_value(ret_regs);
-#endif
+ if (fregs)
+ ftrace_regs_set_instruction_pointer(fregs, ret);
bitmap = get_fgraph_index_bitmap(current, index);
for (i = 0; i < FGRAPH_ARRAY_SIZE; i++) {
@@ -810,7 +825,10 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
if (gops == &fgraph_stub)
continue;
- gops->retfunc(&trace, gops);
+ if (gops->retregfunc)
+ gops->retregfunc(ret_stack->func, ret, fregs, gops);
+ else
+ fgraph_call_retfunc(fregs, ret_regs, ret_stack, gops);
}
/*
@@ -825,20 +843,22 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
return ret;
}
-/*
- * After all architecures have selected HAVE_FUNCTION_GRAPH_RETVAL, we can
- * leave only ftrace_return_to_handler(ret_regs).
- */
-#ifdef CONFIG_HAVE_FUNCTION_GRAPH_RETVAL
+#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FREGS
+unsigned long ftrace_return_to_handler(struct ftrace_regs *fregs)
+{
+ return __ftrace_return_to_handler(fregs, NULL,
+ ftrace_regs_get_frame_pointer(fregs));
+}
+#elif defined(CONFIG_HAVE_FUNCTION_GRAPH_RETVAL)
unsigned long ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs)
{
- return __ftrace_return_to_handler(ret_regs,
+ return __ftrace_return_to_handler(NULL, ret_regs,
fgraph_ret_regs_frame_pointer(ret_regs));
}
#else
unsigned long ftrace_return_to_handler(unsigned long frame_pointer)
{
- return __ftrace_return_to_handler(NULL, frame_pointer);
+ return __ftrace_return_to_handler(NULL, NULL, frame_pointer);
}
#endif
@@ -1191,9 +1211,15 @@ int register_ftrace_graph(struct fgraph_ops *gops)
int ret = 0;
int i;
- if (gops->entryfunc && gops->entryregfunc)
+ if ((gops->entryfunc && gops->entryregfunc) ||
+ (gops->retfunc && gops->retregfunc))
return -EINVAL;
+#ifndef CONFIG_HAVE_FUNCTION_GRAPH_FREGS
+ if (gops->retregfunc)
+ return -EOPNOTSUPP;
+#endif
+
mutex_lock(&ftrace_lock);
if (!gops->ops.func) {
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 21/34] x86/ftrace: Enable HAVE_FUNCTION_GRAPH_FREGS
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (19 preceding siblings ...)
2023-12-18 13:15 ` [PATCH v5 20/34] function_graph: Add a new exit " Masami Hiramatsu (Google)
@ 2023-12-18 13:15 ` Masami Hiramatsu (Google)
2023-12-18 13:15 ` [PATCH v5 22/34] tracing: Rename ftrace_regs_return_value to ftrace_regs_get_return_value Masami Hiramatsu (Google)
` (12 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:15 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Support HAVE_FUNCTION_GRAPH_FREGS on x86-64, which saves ftrace_regs
on the stack in ftrace_graph return trampoline so that the callbacks
can access registers via ftrace_regs APIs.
Note that this only recovers 'rax' and 'rdx' registers because other
registers are not used anymore and recovered by caller. 'rax' and
'rdx' will be used for passing the return value.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Add a comment about rip.
Changes in v2:
- Save rsp register and drop clearing orig_ax.
---
arch/x86/Kconfig | 3 ++-
arch/x86/kernel/ftrace_64.S | 37 +++++++++++++++++++++++++++++--------
2 files changed, 31 insertions(+), 9 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 3762f41bb092..3b955c9e4eb6 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -219,7 +219,8 @@ config X86
select HAVE_FAST_GUP
select HAVE_FENTRY if X86_64 || DYNAMIC_FTRACE
select HAVE_FTRACE_MCOUNT_RECORD
- select HAVE_FUNCTION_GRAPH_RETVAL if HAVE_FUNCTION_GRAPH_TRACER
+ select HAVE_FUNCTION_GRAPH_FREGS if HAVE_DYNAMIC_FTRACE_WITH_ARGS
+ select HAVE_FUNCTION_GRAPH_RETVAL if !HAVE_DYNAMIC_FTRACE_WITH_ARGS
select HAVE_FUNCTION_GRAPH_TRACER if X86_32 || (X86_64 && DYNAMIC_FTRACE)
select HAVE_FUNCTION_TRACER
select HAVE_GCC_PLUGINS
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
index 214f30e9f0c0..8a16f774604e 100644
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -348,21 +348,42 @@ STACK_FRAME_NON_STANDARD_FP(__fentry__)
SYM_CODE_START(return_to_handler)
UNWIND_HINT_UNDEFINED
ANNOTATE_NOENDBR
- subq $24, %rsp
+ /*
+ * Save the registers requires for ftrace_regs;
+ * rax, rcx, rdx, rdi, rsi, r8, r9 and rbp
+ */
+ subq $(FRAME_SIZE), %rsp
+ movq %rax, RAX(%rsp)
+ movq %rcx, RCX(%rsp)
+ movq %rdx, RDX(%rsp)
+ movq %rsi, RSI(%rsp)
+ movq %rdi, RDI(%rsp)
+ movq %r8, R8(%rsp)
+ movq %r9, R9(%rsp)
+ movq %rbp, RBP(%rsp)
+ /*
+ * orig_ax is not cleared because it is used for indicating the direct
+ * trampoline in the fentry. And rip is not set because we don't know
+ * the correct return address here.
+ */
+
+ leaq FRAME_SIZE(%rsp), %rcx
+ movq %rcx, RSP(%rsp)
- /* Save the return values */
- movq %rax, (%rsp)
- movq %rdx, 8(%rsp)
- movq %rbp, 16(%rsp)
movq %rsp, %rdi
call ftrace_return_to_handler
movq %rax, %rdi
- movq 8(%rsp), %rdx
- movq (%rsp), %rax
- addq $24, %rsp
+ /*
+ * Restore only rax and rdx because other registers are not used
+ * for return value nor callee saved. Caller will reuse/recover it.
+ */
+ movq RDX(%rsp), %rdx
+ movq RAX(%rsp), %rax
+
+ addq $(FRAME_SIZE), %rsp
/*
* Jump back to the old return address. This cannot be JMP_NOSPEC rdi
* since IBT would demand that contain ENDBR, which simply isn't so for
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 22/34] tracing: Rename ftrace_regs_return_value to ftrace_regs_get_return_value
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (20 preceding siblings ...)
2023-12-18 13:15 ` [PATCH v5 21/34] x86/ftrace: Enable HAVE_FUNCTION_GRAPH_FREGS Masami Hiramatsu (Google)
@ 2023-12-18 13:15 ` Masami Hiramatsu (Google)
2024-01-05 17:14 ` Mark Rutland
2023-12-18 13:16 ` [PATCH v5 23/34] arm64: ftrace: Enable HAVE_FUNCTION_GRAPH_FREGS Masami Hiramatsu (Google)
` (11 subsequent siblings)
33 siblings, 1 reply; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:15 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Rename ftrace_regs_return_value to ftrace_regs_get_return_value as same as
other ftrace_regs_get/set_* APIs.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Newly added.
---
arch/loongarch/include/asm/ftrace.h | 2 +-
arch/powerpc/include/asm/ftrace.h | 2 +-
arch/s390/include/asm/ftrace.h | 2 +-
arch/x86/include/asm/ftrace.h | 2 +-
include/linux/ftrace.h | 2 +-
kernel/trace/fgraph.c | 2 +-
6 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
index a11996eb5892..a9c3d0f2f941 100644
--- a/arch/loongarch/include/asm/ftrace.h
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -70,7 +70,7 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, unsigned long ip)
regs_get_kernel_argument(&(fregs)->regs, n)
#define ftrace_regs_get_stack_pointer(fregs) \
kernel_stack_pointer(&(fregs)->regs)
-#define ftrace_regs_return_value(fregs) \
+#define ftrace_regs_get_return_value(fregs) \
regs_return_value(&(fregs)->regs)
#define ftrace_regs_set_return_value(fregs, ret) \
regs_set_return_value(&(fregs)->regs, ret)
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index 9e5a39b6a311..7e138e0e3baf 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -69,7 +69,7 @@ ftrace_regs_get_instruction_pointer(struct ftrace_regs *fregs)
regs_get_kernel_argument(&(fregs)->regs, n)
#define ftrace_regs_get_stack_pointer(fregs) \
kernel_stack_pointer(&(fregs)->regs)
-#define ftrace_regs_return_value(fregs) \
+#define ftrace_regs_get_return_value(fregs) \
regs_return_value(&(fregs)->regs)
#define ftrace_regs_set_return_value(fregs, ret) \
regs_set_return_value(&(fregs)->regs, ret)
diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h
index 5a82b08f03cd..01e775c98425 100644
--- a/arch/s390/include/asm/ftrace.h
+++ b/arch/s390/include/asm/ftrace.h
@@ -88,7 +88,7 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
regs_get_kernel_argument(&(fregs)->regs, n)
#define ftrace_regs_get_stack_pointer(fregs) \
kernel_stack_pointer(&(fregs)->regs)
-#define ftrace_regs_return_value(fregs) \
+#define ftrace_regs_get_return_value(fregs) \
regs_return_value(&(fregs)->regs)
#define ftrace_regs_set_return_value(fregs, ret) \
regs_set_return_value(&(fregs)->regs, ret)
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 0b306c82855d..a061f8832b20 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -64,7 +64,7 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs)
regs_get_kernel_argument(&(fregs)->regs, n)
#define ftrace_regs_get_stack_pointer(fregs) \
kernel_stack_pointer(&(fregs)->regs)
-#define ftrace_regs_return_value(fregs) \
+#define ftrace_regs_get_return_value(fregs) \
regs_return_value(&(fregs)->regs)
#define ftrace_regs_set_return_value(fregs, ret) \
regs_set_return_value(&(fregs)->regs, ret)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 79875a00c02b..da2a23f5a9ed 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -187,7 +187,7 @@ static __always_inline bool ftrace_regs_has_args(struct ftrace_regs *fregs)
regs_get_kernel_argument(ftrace_get_regs(fregs), n)
#define ftrace_regs_get_stack_pointer(fregs) \
kernel_stack_pointer(ftrace_get_regs(fregs))
-#define ftrace_regs_return_value(fregs) \
+#define ftrace_regs_get_return_value(fregs) \
regs_return_value(ftrace_get_regs(fregs))
#define ftrace_regs_set_return_value(fregs, ret) \
regs_set_return_value(ftrace_get_regs(fregs), ret)
diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
index 088432b695a6..9a60acaacc96 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -783,7 +783,7 @@ static void fgraph_call_retfunc(struct ftrace_regs *fregs,
trace.rettime = trace_clock_local();
#ifdef CONFIG_FUNCTION_GRAPH_RETVAL
if (fregs)
- trace.retval = ftrace_regs_return_value(fregs);
+ trace.retval = ftrace_regs_get_return_value(fregs);
else
trace.retval = fgraph_ret_regs_return_value(ret_regs);
#endif
^ permalink raw reply related [flat|nested] 56+ messages in thread* Re: [PATCH v5 22/34] tracing: Rename ftrace_regs_return_value to ftrace_regs_get_return_value
2023-12-18 13:15 ` [PATCH v5 22/34] tracing: Rename ftrace_regs_return_value to ftrace_regs_get_return_value Masami Hiramatsu (Google)
@ 2024-01-05 17:14 ` Mark Rutland
2024-01-08 1:09 ` Masami Hiramatsu
0 siblings, 1 reply; 56+ messages in thread
From: Mark Rutland @ 2024-01-05 17:14 UTC (permalink / raw)
To: Masami Hiramatsu (Google)
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Mon, Dec 18, 2023 at 10:15:59PM +0900, Masami Hiramatsu (Google) wrote:
> From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
>
> Rename ftrace_regs_return_value to ftrace_regs_get_return_value as same as
> other ftrace_regs_get/set_* APIs.
>
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Since this is a trivial cleanup, it might make sense to move this to the start
of the series, so that it can be queued even if the later parts need more work.
Mark.
> ---
> Changes in v3:
> - Newly added.
> ---
> arch/loongarch/include/asm/ftrace.h | 2 +-
> arch/powerpc/include/asm/ftrace.h | 2 +-
> arch/s390/include/asm/ftrace.h | 2 +-
> arch/x86/include/asm/ftrace.h | 2 +-
> include/linux/ftrace.h | 2 +-
> kernel/trace/fgraph.c | 2 +-
> 6 files changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
> index a11996eb5892..a9c3d0f2f941 100644
> --- a/arch/loongarch/include/asm/ftrace.h
> +++ b/arch/loongarch/include/asm/ftrace.h
> @@ -70,7 +70,7 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, unsigned long ip)
> regs_get_kernel_argument(&(fregs)->regs, n)
> #define ftrace_regs_get_stack_pointer(fregs) \
> kernel_stack_pointer(&(fregs)->regs)
> -#define ftrace_regs_return_value(fregs) \
> +#define ftrace_regs_get_return_value(fregs) \
> regs_return_value(&(fregs)->regs)
> #define ftrace_regs_set_return_value(fregs, ret) \
> regs_set_return_value(&(fregs)->regs, ret)
> diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
> index 9e5a39b6a311..7e138e0e3baf 100644
> --- a/arch/powerpc/include/asm/ftrace.h
> +++ b/arch/powerpc/include/asm/ftrace.h
> @@ -69,7 +69,7 @@ ftrace_regs_get_instruction_pointer(struct ftrace_regs *fregs)
> regs_get_kernel_argument(&(fregs)->regs, n)
> #define ftrace_regs_get_stack_pointer(fregs) \
> kernel_stack_pointer(&(fregs)->regs)
> -#define ftrace_regs_return_value(fregs) \
> +#define ftrace_regs_get_return_value(fregs) \
> regs_return_value(&(fregs)->regs)
> #define ftrace_regs_set_return_value(fregs, ret) \
> regs_set_return_value(&(fregs)->regs, ret)
> diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h
> index 5a82b08f03cd..01e775c98425 100644
> --- a/arch/s390/include/asm/ftrace.h
> +++ b/arch/s390/include/asm/ftrace.h
> @@ -88,7 +88,7 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
> regs_get_kernel_argument(&(fregs)->regs, n)
> #define ftrace_regs_get_stack_pointer(fregs) \
> kernel_stack_pointer(&(fregs)->regs)
> -#define ftrace_regs_return_value(fregs) \
> +#define ftrace_regs_get_return_value(fregs) \
> regs_return_value(&(fregs)->regs)
> #define ftrace_regs_set_return_value(fregs, ret) \
> regs_set_return_value(&(fregs)->regs, ret)
> diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
> index 0b306c82855d..a061f8832b20 100644
> --- a/arch/x86/include/asm/ftrace.h
> +++ b/arch/x86/include/asm/ftrace.h
> @@ -64,7 +64,7 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs)
> regs_get_kernel_argument(&(fregs)->regs, n)
> #define ftrace_regs_get_stack_pointer(fregs) \
> kernel_stack_pointer(&(fregs)->regs)
> -#define ftrace_regs_return_value(fregs) \
> +#define ftrace_regs_get_return_value(fregs) \
> regs_return_value(&(fregs)->regs)
> #define ftrace_regs_set_return_value(fregs, ret) \
> regs_set_return_value(&(fregs)->regs, ret)
> diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> index 79875a00c02b..da2a23f5a9ed 100644
> --- a/include/linux/ftrace.h
> +++ b/include/linux/ftrace.h
> @@ -187,7 +187,7 @@ static __always_inline bool ftrace_regs_has_args(struct ftrace_regs *fregs)
> regs_get_kernel_argument(ftrace_get_regs(fregs), n)
> #define ftrace_regs_get_stack_pointer(fregs) \
> kernel_stack_pointer(ftrace_get_regs(fregs))
> -#define ftrace_regs_return_value(fregs) \
> +#define ftrace_regs_get_return_value(fregs) \
> regs_return_value(ftrace_get_regs(fregs))
> #define ftrace_regs_set_return_value(fregs, ret) \
> regs_set_return_value(ftrace_get_regs(fregs), ret)
> diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> index 088432b695a6..9a60acaacc96 100644
> --- a/kernel/trace/fgraph.c
> +++ b/kernel/trace/fgraph.c
> @@ -783,7 +783,7 @@ static void fgraph_call_retfunc(struct ftrace_regs *fregs,
> trace.rettime = trace_clock_local();
> #ifdef CONFIG_FUNCTION_GRAPH_RETVAL
> if (fregs)
> - trace.retval = ftrace_regs_return_value(fregs);
> + trace.retval = ftrace_regs_get_return_value(fregs);
> else
> trace.retval = fgraph_ret_regs_return_value(ret_regs);
> #endif
>
^ permalink raw reply [flat|nested] 56+ messages in thread
* Re: [PATCH v5 22/34] tracing: Rename ftrace_regs_return_value to ftrace_regs_get_return_value
2024-01-05 17:14 ` Mark Rutland
@ 2024-01-08 1:09 ` Masami Hiramatsu
0 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu @ 2024-01-08 1:09 UTC (permalink / raw)
To: Mark Rutland
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Fri, 5 Jan 2024 17:14:06 +0000
Mark Rutland <mark.rutland@arm.com> wrote:
> On Mon, Dec 18, 2023 at 10:15:59PM +0900, Masami Hiramatsu (Google) wrote:
> > From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> >
> > Rename ftrace_regs_return_value to ftrace_regs_get_return_value as same as
> > other ftrace_regs_get/set_* APIs.
> >
> > Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
>
> Acked-by: Mark Rutland <mark.rutland@arm.com>
>
> Since this is a trivial cleanup, it might make sense to move this to the start
> of the series, so that it can be queued even if the later parts need more work.
Thanks for your Ack! and OK, let me move this to the start of this series.
>
> Mark.
>
> > ---
> > Changes in v3:
> > - Newly added.
> > ---
> > arch/loongarch/include/asm/ftrace.h | 2 +-
> > arch/powerpc/include/asm/ftrace.h | 2 +-
> > arch/s390/include/asm/ftrace.h | 2 +-
> > arch/x86/include/asm/ftrace.h | 2 +-
> > include/linux/ftrace.h | 2 +-
> > kernel/trace/fgraph.c | 2 +-
> > 6 files changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
> > index a11996eb5892..a9c3d0f2f941 100644
> > --- a/arch/loongarch/include/asm/ftrace.h
> > +++ b/arch/loongarch/include/asm/ftrace.h
> > @@ -70,7 +70,7 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs, unsigned long ip)
> > regs_get_kernel_argument(&(fregs)->regs, n)
> > #define ftrace_regs_get_stack_pointer(fregs) \
> > kernel_stack_pointer(&(fregs)->regs)
> > -#define ftrace_regs_return_value(fregs) \
> > +#define ftrace_regs_get_return_value(fregs) \
> > regs_return_value(&(fregs)->regs)
> > #define ftrace_regs_set_return_value(fregs, ret) \
> > regs_set_return_value(&(fregs)->regs, ret)
> > diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
> > index 9e5a39b6a311..7e138e0e3baf 100644
> > --- a/arch/powerpc/include/asm/ftrace.h
> > +++ b/arch/powerpc/include/asm/ftrace.h
> > @@ -69,7 +69,7 @@ ftrace_regs_get_instruction_pointer(struct ftrace_regs *fregs)
> > regs_get_kernel_argument(&(fregs)->regs, n)
> > #define ftrace_regs_get_stack_pointer(fregs) \
> > kernel_stack_pointer(&(fregs)->regs)
> > -#define ftrace_regs_return_value(fregs) \
> > +#define ftrace_regs_get_return_value(fregs) \
> > regs_return_value(&(fregs)->regs)
> > #define ftrace_regs_set_return_value(fregs, ret) \
> > regs_set_return_value(&(fregs)->regs, ret)
> > diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h
> > index 5a82b08f03cd..01e775c98425 100644
> > --- a/arch/s390/include/asm/ftrace.h
> > +++ b/arch/s390/include/asm/ftrace.h
> > @@ -88,7 +88,7 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
> > regs_get_kernel_argument(&(fregs)->regs, n)
> > #define ftrace_regs_get_stack_pointer(fregs) \
> > kernel_stack_pointer(&(fregs)->regs)
> > -#define ftrace_regs_return_value(fregs) \
> > +#define ftrace_regs_get_return_value(fregs) \
> > regs_return_value(&(fregs)->regs)
> > #define ftrace_regs_set_return_value(fregs, ret) \
> > regs_set_return_value(&(fregs)->regs, ret)
> > diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
> > index 0b306c82855d..a061f8832b20 100644
> > --- a/arch/x86/include/asm/ftrace.h
> > +++ b/arch/x86/include/asm/ftrace.h
> > @@ -64,7 +64,7 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs)
> > regs_get_kernel_argument(&(fregs)->regs, n)
> > #define ftrace_regs_get_stack_pointer(fregs) \
> > kernel_stack_pointer(&(fregs)->regs)
> > -#define ftrace_regs_return_value(fregs) \
> > +#define ftrace_regs_get_return_value(fregs) \
> > regs_return_value(&(fregs)->regs)
> > #define ftrace_regs_set_return_value(fregs, ret) \
> > regs_set_return_value(&(fregs)->regs, ret)
> > diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
> > index 79875a00c02b..da2a23f5a9ed 100644
> > --- a/include/linux/ftrace.h
> > +++ b/include/linux/ftrace.h
> > @@ -187,7 +187,7 @@ static __always_inline bool ftrace_regs_has_args(struct ftrace_regs *fregs)
> > regs_get_kernel_argument(ftrace_get_regs(fregs), n)
> > #define ftrace_regs_get_stack_pointer(fregs) \
> > kernel_stack_pointer(ftrace_get_regs(fregs))
> > -#define ftrace_regs_return_value(fregs) \
> > +#define ftrace_regs_get_return_value(fregs) \
> > regs_return_value(ftrace_get_regs(fregs))
> > #define ftrace_regs_set_return_value(fregs, ret) \
> > regs_set_return_value(ftrace_get_regs(fregs), ret)
> > diff --git a/kernel/trace/fgraph.c b/kernel/trace/fgraph.c
> > index 088432b695a6..9a60acaacc96 100644
> > --- a/kernel/trace/fgraph.c
> > +++ b/kernel/trace/fgraph.c
> > @@ -783,7 +783,7 @@ static void fgraph_call_retfunc(struct ftrace_regs *fregs,
> > trace.rettime = trace_clock_local();
> > #ifdef CONFIG_FUNCTION_GRAPH_RETVAL
> > if (fregs)
> > - trace.retval = ftrace_regs_return_value(fregs);
> > + trace.retval = ftrace_regs_get_return_value(fregs);
> > else
> > trace.retval = fgraph_ret_regs_return_value(ret_regs);
> > #endif
> >
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 56+ messages in thread
* [PATCH v5 23/34] arm64: ftrace: Enable HAVE_FUNCTION_GRAPH_FREGS
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (21 preceding siblings ...)
2023-12-18 13:15 ` [PATCH v5 22/34] tracing: Rename ftrace_regs_return_value to ftrace_regs_get_return_value Masami Hiramatsu (Google)
@ 2023-12-18 13:16 ` Masami Hiramatsu (Google)
2023-12-18 13:16 ` [PATCH v5 24/34] fprobe: Use ftrace_regs in fprobe entry handler Masami Hiramatsu (Google)
` (10 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:16 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Enable CONFIG_HAVE_FUNCTION_GRAPH_FREGS on arm64. Note that this
depends on HAVE_DYNAMIC_FTRACE_WITH_ARGS which is enabled if the
compiler supports "-fpatchable-function-entry=2". If not, it
continue to use ftrace_ret_regs.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Newly added.
---
arch/arm64/Kconfig | 2 ++
arch/arm64/include/asm/ftrace.h | 6 ++++++
arch/arm64/kernel/entry-ftrace.S | 28 ++++++++++++++++++++++++++++
3 files changed, 36 insertions(+)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7b071a00425d..beebc724dcae 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -192,6 +192,8 @@ config ARM64
select HAVE_DYNAMIC_FTRACE
select HAVE_DYNAMIC_FTRACE_WITH_ARGS \
if $(cc-option,-fpatchable-function-entry=2)
+ select HAVE_FUNCTION_GRAPH_FREGS \
+ if HAVE_DYNAMIC_FTRACE_WITH_ARGS
select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS \
if DYNAMIC_FTRACE_WITH_ARGS && DYNAMIC_FTRACE_WITH_CALL_OPS
select HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS \
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index ab158196480c..efd5dbf74dd6 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -131,6 +131,12 @@ ftrace_regs_set_return_value(struct ftrace_regs *fregs,
fregs->regs[0] = ret;
}
+static __always_inline unsigned long
+ftrace_regs_get_frame_pointer(struct ftrace_regs *fregs)
+{
+ return fregs->fp;
+}
+
static __always_inline void
ftrace_override_function_with_return(struct ftrace_regs *fregs)
{
diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S
index f0c16640ef21..d87ccdb9e678 100644
--- a/arch/arm64/kernel/entry-ftrace.S
+++ b/arch/arm64/kernel/entry-ftrace.S
@@ -328,6 +328,33 @@ SYM_FUNC_END(ftrace_stub_graph)
* Run ftrace_return_to_handler() before going back to parent.
* @fp is checked against the value passed by ftrace_graph_caller().
*/
+#ifdef CONFIG_HAVE_FUNCTION_GRAPH_FREGS
+SYM_CODE_START(return_to_handler)
+ /* save ftrace_regs except for PC */
+ sub sp, sp, #FREGS_SIZE
+ stp x0, x1, [sp, #FREGS_X0]
+ stp x2, x3, [sp, #FREGS_X2]
+ stp x4, x5, [sp, #FREGS_X4]
+ stp x6, x7, [sp, #FREGS_X6]
+ str x8, [sp, #FREGS_X8]
+ str x29, [sp, #FREGS_FP]
+ str x9, [sp, #FREGS_LR]
+ str x10, [sp, #FREGS_SP]
+
+ mov x0, sp
+ bl ftrace_return_to_handler // addr = ftrace_return_to_hander(fregs);
+ mov x30, x0 // restore the original return address
+
+ /* restore return value regs */
+ ldp x0, x1, [sp, #FREGS_X0]
+ ldp x2, x3, [sp, #FREGS_X2]
+ ldp x4, x5, [sp, #FREGS_X4]
+ ldp x6, x7, [sp, #FREGS_X6]
+ add sp, sp, #FREGS_SIZE
+
+ ret
+SYM_CODE_END(return_to_handler)
+#else /* !CONFIG_HAVE_FUNCTION_GRAPH_FREGS */
SYM_CODE_START(return_to_handler)
/* save return value regs */
sub sp, sp, #FGRET_REGS_SIZE
@@ -350,4 +377,5 @@ SYM_CODE_START(return_to_handler)
ret
SYM_CODE_END(return_to_handler)
+#endif /* CONFIG_HAVE_FUNCTION_GRAPH_FREGS */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 24/34] fprobe: Use ftrace_regs in fprobe entry handler
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (22 preceding siblings ...)
2023-12-18 13:16 ` [PATCH v5 23/34] arm64: ftrace: Enable HAVE_FUNCTION_GRAPH_FREGS Masami Hiramatsu (Google)
@ 2023-12-18 13:16 ` Masami Hiramatsu (Google)
2023-12-19 13:23 ` Jiri Olsa
2023-12-19 13:23 ` Jiri Olsa
2023-12-18 13:16 ` [PATCH v5 25/34] fprobe: Use ftrace_regs in fprobe exit handler Masami Hiramatsu (Google)
` (9 subsequent siblings)
33 siblings, 2 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:16 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
This allows fprobes to be available with CONFIG_DYNAMIC_FTRACE_WITH_ARGS
instead of CONFIG_DYNAMIC_FTRACE_WITH_REGS, then we can enable fprobe
on arm64.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Florent Revest <revest@chromium.org>
---
Changes from previous series: NOTHING, just forward ported.
---
include/linux/fprobe.h | 2 +-
kernel/trace/Kconfig | 3 ++-
kernel/trace/bpf_trace.c | 10 +++++++---
kernel/trace/fprobe.c | 4 ++--
kernel/trace/trace_fprobe.c | 6 +++++-
lib/test_fprobe.c | 4 ++--
samples/fprobe/fprobe_example.c | 2 +-
7 files changed, 20 insertions(+), 11 deletions(-)
diff --git a/include/linux/fprobe.h b/include/linux/fprobe.h
index 3e03758151f4..36c0595f7b93 100644
--- a/include/linux/fprobe.h
+++ b/include/linux/fprobe.h
@@ -35,7 +35,7 @@ struct fprobe {
int nr_maxactive;
int (*entry_handler)(struct fprobe *fp, unsigned long entry_ip,
- unsigned long ret_ip, struct pt_regs *regs,
+ unsigned long ret_ip, struct ftrace_regs *regs,
void *entry_data);
void (*exit_handler)(struct fprobe *fp, unsigned long entry_ip,
unsigned long ret_ip, struct pt_regs *regs,
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 308b3bec01b1..805d72ab77c6 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -290,7 +290,7 @@ config DYNAMIC_FTRACE_WITH_ARGS
config FPROBE
bool "Kernel Function Probe (fprobe)"
depends on FUNCTION_TRACER
- depends on DYNAMIC_FTRACE_WITH_REGS
+ depends on DYNAMIC_FTRACE_WITH_REGS || DYNAMIC_FTRACE_WITH_ARGS
depends on HAVE_RETHOOK
select RETHOOK
default n
@@ -675,6 +675,7 @@ config FPROBE_EVENTS
select TRACING
select PROBE_EVENTS
select DYNAMIC_EVENTS
+ depends on DYNAMIC_FTRACE_WITH_REGS
default y
help
This allows user to add tracing events on the function entry and
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 84e8a0f6e4e0..d3f8745d8ead 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2503,7 +2503,7 @@ static int __init bpf_event_init(void)
fs_initcall(bpf_event_init);
#endif /* CONFIG_MODULES */
-#ifdef CONFIG_FPROBE
+#if defined(CONFIG_FPROBE) && defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS)
struct bpf_kprobe_multi_link {
struct bpf_link link;
struct fprobe fp;
@@ -2733,10 +2733,14 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
static int
kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip,
- unsigned long ret_ip, struct pt_regs *regs,
+ unsigned long ret_ip, struct ftrace_regs *fregs,
void *data)
{
struct bpf_kprobe_multi_link *link;
+ struct pt_regs *regs = ftrace_get_regs(fregs);
+
+ if (!regs)
+ return 0;
link = container_of(fp, struct bpf_kprobe_multi_link, fp);
kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs);
@@ -3008,7 +3012,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
kvfree(cookies);
return err;
}
-#else /* !CONFIG_FPROBE */
+#else /* !CONFIG_FPROBE || !CONFIG_DYNAMIC_FTRACE_WITH_REGS */
int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
return -EOPNOTSUPP;
diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index 6cd2a4e3afb8..f12569494d8a 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -46,7 +46,7 @@ static inline void __fprobe_handler(unsigned long ip, unsigned long parent_ip,
}
if (fp->entry_handler)
- ret = fp->entry_handler(fp, ip, parent_ip, ftrace_get_regs(fregs), entry_data);
+ ret = fp->entry_handler(fp, ip, parent_ip, fregs, entry_data);
/* If entry_handler returns !0, nmissed is not counted. */
if (rh) {
@@ -182,7 +182,7 @@ static void fprobe_init(struct fprobe *fp)
fp->ops.func = fprobe_kprobe_handler;
else
fp->ops.func = fprobe_handler;
- fp->ops.flags |= FTRACE_OPS_FL_SAVE_REGS;
+ fp->ops.flags |= FTRACE_OPS_FL_SAVE_ARGS;
}
static int fprobe_init_rethook(struct fprobe *fp, int num)
diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
index 7d2ddbcfa377..ef6b36fd05ae 100644
--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -320,12 +320,16 @@ NOKPROBE_SYMBOL(fexit_perf_func);
#endif /* CONFIG_PERF_EVENTS */
static int fentry_dispatcher(struct fprobe *fp, unsigned long entry_ip,
- unsigned long ret_ip, struct pt_regs *regs,
+ unsigned long ret_ip, struct ftrace_regs *fregs,
void *entry_data)
{
struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp);
+ struct pt_regs *regs = ftrace_get_regs(fregs);
int ret = 0;
+ if (!regs)
+ return 0;
+
if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
fentry_trace_func(tf, entry_ip, regs);
#ifdef CONFIG_PERF_EVENTS
diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
index 24de0e5ff859..ff607babba18 100644
--- a/lib/test_fprobe.c
+++ b/lib/test_fprobe.c
@@ -40,7 +40,7 @@ static noinline u32 fprobe_selftest_nest_target(u32 value, u32 (*nest)(u32))
static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip,
unsigned long ret_ip,
- struct pt_regs *regs, void *data)
+ struct ftrace_regs *fregs, void *data)
{
KUNIT_EXPECT_FALSE(current_test, preemptible());
/* This can be called on the fprobe_selftest_target and the fprobe_selftest_target2 */
@@ -81,7 +81,7 @@ static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip,
static notrace int nest_entry_handler(struct fprobe *fp, unsigned long ip,
unsigned long ret_ip,
- struct pt_regs *regs, void *data)
+ struct ftrace_regs *fregs, void *data)
{
KUNIT_EXPECT_FALSE(current_test, preemptible());
return 0;
diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c
index 64e715e7ed11..1545a1aac616 100644
--- a/samples/fprobe/fprobe_example.c
+++ b/samples/fprobe/fprobe_example.c
@@ -50,7 +50,7 @@ static void show_backtrace(void)
static int sample_entry_handler(struct fprobe *fp, unsigned long ip,
unsigned long ret_ip,
- struct pt_regs *regs, void *data)
+ struct ftrace_regs *fregs, void *data)
{
if (use_trace)
/*
^ permalink raw reply related [flat|nested] 56+ messages in thread* Re: [PATCH v5 24/34] fprobe: Use ftrace_regs in fprobe entry handler
2023-12-18 13:16 ` [PATCH v5 24/34] fprobe: Use ftrace_regs in fprobe entry handler Masami Hiramatsu (Google)
@ 2023-12-19 13:23 ` Jiri Olsa
2023-12-19 13:23 ` Jiri Olsa
1 sibling, 0 replies; 56+ messages in thread
From: Jiri Olsa @ 2023-12-19 13:23 UTC (permalink / raw)
To: Masami Hiramatsu (Google)
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Arnaldo Carvalho de Melo, Daniel Borkmann,
Alan Maguire, Mark Rutland, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Mon, Dec 18, 2023 at 10:16:23PM +0900, Masami Hiramatsu (Google) wrote:
> From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
>
> This allows fprobes to be available with CONFIG_DYNAMIC_FTRACE_WITH_ARGS
> instead of CONFIG_DYNAMIC_FTRACE_WITH_REGS, then we can enable fprobe
> on arm64.
>
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> Acked-by: Florent Revest <revest@chromium.org>
this change breaks kprobe multi bpf tests (crash below), which are
partially fixed by [1] later on, but I think we have to keep
bisecting crash free
it looks like the rethook will get wrong pointer.. I'm still trying
to digest the whole thing, so I might have some updates later ;-)
jirka
[1] fprobe: Rewrite fprobe on function-graph tracer
---
Dec 19 13:50:04 qemu kernel: BUG: kernel NULL pointer dereference, address: 0000000000000098
Dec 19 13:50:04 qemu kernel: #PF: supervisor read access in kernel mode
Dec 19 13:50:04 qemu kernel: #PF: error_code(0x0000) - not-present page
Dec 19 13:50:04 qemu kernel: PGD 10955f067 P4D 10955f067 PUD 103113067 PMD 0
Dec 19 13:50:04 qemu kernel: Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC KASAN NOPTI
Dec 19 13:50:04 qemu kernel: CPU: 1 PID: 747 Comm: test_progs Tainted: G B OE 6.7.0-rc3+ #194 85bc8297edbc7f21acfc743dabbd52cac073a6bf
Dec 19 13:50:04 qemu kernel: Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014
Dec 19 13:50:04 qemu kernel: RIP: 0010:arch_rethook_prepare+0x18/0x60
Dec 19 13:50:04 qemu kernel: Code: 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 41 55 41 54 55 48 89 f5 53 48 89 fb 48 8d be 98 00 00 00 e8 68 8f 59 >
Dec 19 13:50:04 qemu kernel: RSP: 0018:ffff888125f97a88 EFLAGS: 00010286
Dec 19 13:50:04 qemu kernel: RAX: 0000000000000001 RBX: ffff88818a231410 RCX: ffffffff812190b6
Dec 19 13:50:04 qemu kernel: RDX: fffffbfff0c42e95 RSI: 0000000000000008 RDI: ffffffff862174a0
Dec 19 13:50:04 qemu kernel: RBP: 0000000000000000 R08: 0000000000000001 R09: fffffbfff0c42e94
Dec 19 13:50:04 qemu kernel: R10: ffffffff862174a7 R11: 0000000000000000 R12: ffff88818a231420
Dec 19 13:50:04 qemu kernel: R13: ffffffff8283ee8e R14: ffff88818a231410 R15: fffffffffffffff7
Dec 19 13:50:04 qemu kernel: FS: 00007ff8a16cfd00(0000) GS:ffff88842c600000(0000) knlGS:0000000000000000
Dec 19 13:50:05 qemu kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Dec 19 13:50:05 qemu kernel: CR2: 0000000000000098 CR3: 000000010633c005 CR4: 0000000000770ef0
Dec 19 13:50:05 qemu kernel: PKRU: 55555554
Dec 19 13:50:05 qemu kernel: Call Trace:
Dec 19 13:50:05 qemu kernel: <TASK>
Dec 19 13:50:05 qemu kernel: ? __die+0x1f/0x70
Dec 19 13:50:05 qemu kernel: ? page_fault_oops+0x215/0x620
Dec 19 13:50:05 qemu kernel: ? rcu_is_watching+0x34/0x60
Dec 19 13:50:05 qemu kernel: ? __pfx_page_fault_oops+0x10/0x10
Dec 19 13:50:05 qemu kernel: ? asm_sysvec_apic_timer_interrupt+0x16/0x20
Dec 19 13:50:05 qemu kernel: ? do_user_addr_fault+0x4b3/0x910
Dec 19 13:50:05 qemu kernel: ? exc_page_fault+0x77/0x130
Dec 19 13:50:05 qemu kernel: ? asm_exc_page_fault+0x22/0x30
Dec 19 13:50:05 qemu kernel: ? bpf_prog_test_run_tracing+0x1ce/0x2d0
Dec 19 13:50:05 qemu kernel: ? add_taint+0x26/0x90
Dec 19 13:50:05 qemu kernel: ? arch_rethook_prepare+0x18/0x60
Dec 19 13:50:05 qemu kernel: ? arch_rethook_prepare+0x18/0x60
Dec 19 13:50:05 qemu kernel: ? bpf_prog_test_run_tracing+0x1ce/0x2d0
Dec 19 13:50:05 qemu kernel: rethook_hook+0x1e/0x50
Dec 19 13:50:05 qemu kernel: ? __pfx_bpf_fentry_test1+0x10/0x10
Dec 19 13:50:05 qemu kernel: ? bpf_prog_test_run_tracing+0x1ce/0x2d0
Dec 19 13:50:05 qemu kernel: fprobe_handler+0x1ca/0x350
Dec 19 13:50:05 qemu kernel: ? __pfx_bpf_fentry_test1+0x10/0x10
Dec 19 13:50:05 qemu kernel: arch_ftrace_ops_list_func+0x143/0x2e0
Dec 19 13:50:05 qemu kernel: ? bpf_prog_test_run_tracing+0x1ce/0x2d0
Dec 19 13:50:05 qemu kernel: ftrace_call+0x5/0x44
Dec 19 13:50:05 qemu kernel: ? __pfx_lock_release+0x10/0x10
Dec 19 13:50:05 qemu kernel: ? rcu_is_watching+0x34/0x60
Dec 19 13:50:05 qemu kernel: ? bpf_prog_test_run_tracing+0xcd/0x2d0
Dec 19 13:50:05 qemu kernel: ? bpf_fentry_test1+0x5/0x10
Dec 19 13:50:05 qemu kernel: ? rcu_is_watching+0x34/0x60
Dec 19 13:50:05 qemu kernel: bpf_fentry_test1+0x5/0x10
Dec 19 13:50:05 qemu kernel: bpf_prog_test_run_tracing+0x1ce/0x2d0
Dec 19 13:50:05 qemu kernel: ? __pfx_lock_release+0x10/0x10
Dec 19 13:50:05 qemu kernel: ? __pfx_bpf_prog_test_run_tracing+0x10/0x10
Dec 19 13:50:05 qemu kernel: ? __pfx_lock_release+0x10/0x10
Dec 19 13:50:05 qemu kernel: ? __fget_light+0xdf/0x100
Dec 19 13:50:05 qemu kernel: ? __bpf_prog_get+0x107/0x150
Dec 19 13:50:05 qemu kernel: __sys_bpf+0x552/0x2ef0
Dec 19 13:50:05 qemu kernel: ? rcu_is_watching+0x34/0x60
Dec 19 13:50:05 qemu kernel: ? __pfx___sys_bpf+0x10/0x10
Dec 19 13:50:05 qemu kernel: ? __pfx_lock_release+0x10/0x10
Dec 19 13:50:05 qemu kernel: ? vfs_write+0x1fa/0x740
Dec 19 13:50:05 qemu kernel: ? rcu_is_watching+0x34/0x60
Dec 19 13:50:05 qemu kernel: ? rcu_is_watching+0x34/0x60
Dec 19 13:50:05 qemu kernel: ? lockdep_hardirqs_on_prepare+0xe/0x250
Dec 19 13:50:05 qemu kernel: ? seqcount_lockdep_reader_access.constprop.0+0x105/0x120
Dec 19 13:50:05 qemu kernel: ? seqcount_lockdep_reader_access.constprop.0+0xb2/0x120
Dec 19 13:50:05 qemu kernel: __x64_sys_bpf+0x44/0x60
Dec 19 13:50:05 qemu kernel: do_syscall_64+0x3f/0xf0
Dec 19 13:50:05 qemu kernel: entry_SYSCALL_64_after_hwframe+0x6e/0x76
Dec 19 13:50:05 qemu kernel: RIP: 0033:0x7ff8a1897b4d
Dec 19 13:50:05 qemu kernel: Code: c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f >
Dec 19 13:50:05 qemu kernel: RSP: 002b:00007fff34f7d158 EFLAGS: 00000206 ORIG_RAX: 0000000000000141
Dec 19 13:50:05 qemu kernel: RAX: ffffffffffffffda RBX: 00007ff8a19aa000 RCX: 00007ff8a1897b4d
Dec 19 13:50:05 qemu kernel: RDX: 0000000000000050 RSI: 00007fff34f7d190 RDI: 000000000000000a
Dec 19 13:50:05 qemu kernel: RBP: 00007fff34f7d170 R08: 0000000000000000 R09: 00007fff34f7d190
Dec 19 13:50:05 qemu kernel: R10: 0000000000000064 R11: 0000000000000206 R12: 0000000000000004
Dec 19 13:50:05 qemu kernel: R13: 0000000000000000 R14: 00007ff8a19df000 R15: 0000000000e56db0
Dec 19 13:50:05 qemu kernel: </TASK>
Dec 19 13:50:05 qemu kernel: Modules linked in: bpf_testmod(OE) intel_rapl_msr intel_rapl_common crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_inte>
Dec 19 13:50:05 qemu kernel: CR2: 0000000000000098
Dec 19 13:50:05 qemu kernel: ---[ end trace 0000000000000000 ]---
^ permalink raw reply [flat|nested] 56+ messages in thread
* Re: [PATCH v5 24/34] fprobe: Use ftrace_regs in fprobe entry handler
2023-12-18 13:16 ` [PATCH v5 24/34] fprobe: Use ftrace_regs in fprobe entry handler Masami Hiramatsu (Google)
2023-12-19 13:23 ` Jiri Olsa
@ 2023-12-19 13:23 ` Jiri Olsa
2023-12-19 22:51 ` Masami Hiramatsu
1 sibling, 1 reply; 56+ messages in thread
From: Jiri Olsa @ 2023-12-19 13:23 UTC (permalink / raw)
To: Masami Hiramatsu (Google)
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Arnaldo Carvalho de Melo, Daniel Borkmann,
Alan Maguire, Mark Rutland, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Mon, Dec 18, 2023 at 10:16:23PM +0900, Masami Hiramatsu (Google) wrote:
SNIP
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 84e8a0f6e4e0..d3f8745d8ead 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -2503,7 +2503,7 @@ static int __init bpf_event_init(void)
> fs_initcall(bpf_event_init);
> #endif /* CONFIG_MODULES */
>
> -#ifdef CONFIG_FPROBE
> +#if defined(CONFIG_FPROBE) && defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS)
> struct bpf_kprobe_multi_link {
> struct bpf_link link;
> struct fprobe fp;
> @@ -2733,10 +2733,14 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
>
> static int
> kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip,
> - unsigned long ret_ip, struct pt_regs *regs,
> + unsigned long ret_ip, struct ftrace_regs *fregs,
> void *data)
> {
> struct bpf_kprobe_multi_link *link;
> + struct pt_regs *regs = ftrace_get_regs(fregs);
> +
> + if (!regs)
> + return 0;
>
> link = container_of(fp, struct bpf_kprobe_multi_link, fp);
> kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs);
> @@ -3008,7 +3012,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> kvfree(cookies);
> return err;
> }
> -#else /* !CONFIG_FPROBE */
> +#else /* !CONFIG_FPROBE || !CONFIG_DYNAMIC_FTRACE_WITH_REGS */
> int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
> {
> return -EOPNOTSUPP;
> diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
> index 6cd2a4e3afb8..f12569494d8a 100644
> --- a/kernel/trace/fprobe.c
> +++ b/kernel/trace/fprobe.c
> @@ -46,7 +46,7 @@ static inline void __fprobe_handler(unsigned long ip, unsigned long parent_ip,
> }
>
> if (fp->entry_handler)
> - ret = fp->entry_handler(fp, ip, parent_ip, ftrace_get_regs(fregs), entry_data);
> + ret = fp->entry_handler(fp, ip, parent_ip, fregs, entry_data);
>
> /* If entry_handler returns !0, nmissed is not counted. */
> if (rh) {
> @@ -182,7 +182,7 @@ static void fprobe_init(struct fprobe *fp)
> fp->ops.func = fprobe_kprobe_handler;
> else
> fp->ops.func = fprobe_handler;
> - fp->ops.flags |= FTRACE_OPS_FL_SAVE_REGS;
> + fp->ops.flags |= FTRACE_OPS_FL_SAVE_ARGS;
so with this change you move to ftrace_caller trampoline,
but we need ftrace_regs_caller right?
otherwise the (!regs) check in kprobe_multi_link_handler
will be allways true IIUC
jirka
> }
>
> static int fprobe_init_rethook(struct fprobe *fp, int num)
> diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
> index 7d2ddbcfa377..ef6b36fd05ae 100644
> --- a/kernel/trace/trace_fprobe.c
> +++ b/kernel/trace/trace_fprobe.c
> @@ -320,12 +320,16 @@ NOKPROBE_SYMBOL(fexit_perf_func);
> #endif /* CONFIG_PERF_EVENTS */
>
> static int fentry_dispatcher(struct fprobe *fp, unsigned long entry_ip,
> - unsigned long ret_ip, struct pt_regs *regs,
> + unsigned long ret_ip, struct ftrace_regs *fregs,
> void *entry_data)
> {
> struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp);
> + struct pt_regs *regs = ftrace_get_regs(fregs);
> int ret = 0;
>
> + if (!regs)
> + return 0;
> +
> if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
> fentry_trace_func(tf, entry_ip, regs);
> #ifdef CONFIG_PERF_EVENTS
> diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
> index 24de0e5ff859..ff607babba18 100644
> --- a/lib/test_fprobe.c
> +++ b/lib/test_fprobe.c
> @@ -40,7 +40,7 @@ static noinline u32 fprobe_selftest_nest_target(u32 value, u32 (*nest)(u32))
>
> static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip,
> unsigned long ret_ip,
> - struct pt_regs *regs, void *data)
> + struct ftrace_regs *fregs, void *data)
> {
> KUNIT_EXPECT_FALSE(current_test, preemptible());
> /* This can be called on the fprobe_selftest_target and the fprobe_selftest_target2 */
> @@ -81,7 +81,7 @@ static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip,
>
> static notrace int nest_entry_handler(struct fprobe *fp, unsigned long ip,
> unsigned long ret_ip,
> - struct pt_regs *regs, void *data)
> + struct ftrace_regs *fregs, void *data)
> {
> KUNIT_EXPECT_FALSE(current_test, preemptible());
> return 0;
> diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c
> index 64e715e7ed11..1545a1aac616 100644
> --- a/samples/fprobe/fprobe_example.c
> +++ b/samples/fprobe/fprobe_example.c
> @@ -50,7 +50,7 @@ static void show_backtrace(void)
>
> static int sample_entry_handler(struct fprobe *fp, unsigned long ip,
> unsigned long ret_ip,
> - struct pt_regs *regs, void *data)
> + struct ftrace_regs *fregs, void *data)
> {
> if (use_trace)
> /*
>
^ permalink raw reply [flat|nested] 56+ messages in thread* Re: [PATCH v5 24/34] fprobe: Use ftrace_regs in fprobe entry handler
2023-12-19 13:23 ` Jiri Olsa
@ 2023-12-19 22:51 ` Masami Hiramatsu
0 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu @ 2023-12-19 22:51 UTC (permalink / raw)
To: Jiri Olsa
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Arnaldo Carvalho de Melo, Daniel Borkmann,
Alan Maguire, Mark Rutland, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Tue, 19 Dec 2023 14:23:48 +0100
Jiri Olsa <olsajiri@gmail.com> wrote:
> On Mon, Dec 18, 2023 at 10:16:23PM +0900, Masami Hiramatsu (Google) wrote:
>
> SNIP
>
> > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > index 84e8a0f6e4e0..d3f8745d8ead 100644
> > --- a/kernel/trace/bpf_trace.c
> > +++ b/kernel/trace/bpf_trace.c
> > @@ -2503,7 +2503,7 @@ static int __init bpf_event_init(void)
> > fs_initcall(bpf_event_init);
> > #endif /* CONFIG_MODULES */
> >
> > -#ifdef CONFIG_FPROBE
> > +#if defined(CONFIG_FPROBE) && defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS)
> > struct bpf_kprobe_multi_link {
> > struct bpf_link link;
> > struct fprobe fp;
> > @@ -2733,10 +2733,14 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
> >
> > static int
> > kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip,
> > - unsigned long ret_ip, struct pt_regs *regs,
> > + unsigned long ret_ip, struct ftrace_regs *fregs,
> > void *data)
> > {
> > struct bpf_kprobe_multi_link *link;
> > + struct pt_regs *regs = ftrace_get_regs(fregs);
> > +
> > + if (!regs)
> > + return 0;
> >
> > link = container_of(fp, struct bpf_kprobe_multi_link, fp);
> > kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs);
> > @@ -3008,7 +3012,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
> > kvfree(cookies);
> > return err;
> > }
> > -#else /* !CONFIG_FPROBE */
> > +#else /* !CONFIG_FPROBE || !CONFIG_DYNAMIC_FTRACE_WITH_REGS */
> > int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
> > {
> > return -EOPNOTSUPP;
> > diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
> > index 6cd2a4e3afb8..f12569494d8a 100644
> > --- a/kernel/trace/fprobe.c
> > +++ b/kernel/trace/fprobe.c
> > @@ -46,7 +46,7 @@ static inline void __fprobe_handler(unsigned long ip, unsigned long parent_ip,
> > }
> >
> > if (fp->entry_handler)
> > - ret = fp->entry_handler(fp, ip, parent_ip, ftrace_get_regs(fregs), entry_data);
> > + ret = fp->entry_handler(fp, ip, parent_ip, fregs, entry_data);
> >
> > /* If entry_handler returns !0, nmissed is not counted. */
> > if (rh) {
> > @@ -182,7 +182,7 @@ static void fprobe_init(struct fprobe *fp)
> > fp->ops.func = fprobe_kprobe_handler;
> > else
> > fp->ops.func = fprobe_handler;
> > - fp->ops.flags |= FTRACE_OPS_FL_SAVE_REGS;
> > + fp->ops.flags |= FTRACE_OPS_FL_SAVE_ARGS;
>
> so with this change you move to ftrace_caller trampoline,
> but we need ftrace_regs_caller right?
Yes, that's right.
>
> otherwise the (!regs) check in kprobe_multi_link_handler
> will be allways true IIUC
Ah, OK. So until we move to fgraph [28/34], keep this flag SAVE_REGS
then kprobe_multi test will pass.
OK, let me keep it so.
Thank you!
>
> jirka
>
> > }
> >
> > static int fprobe_init_rethook(struct fprobe *fp, int num)
> > diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
> > index 7d2ddbcfa377..ef6b36fd05ae 100644
> > --- a/kernel/trace/trace_fprobe.c
> > +++ b/kernel/trace/trace_fprobe.c
> > @@ -320,12 +320,16 @@ NOKPROBE_SYMBOL(fexit_perf_func);
> > #endif /* CONFIG_PERF_EVENTS */
> >
> > static int fentry_dispatcher(struct fprobe *fp, unsigned long entry_ip,
> > - unsigned long ret_ip, struct pt_regs *regs,
> > + unsigned long ret_ip, struct ftrace_regs *fregs,
> > void *entry_data)
> > {
> > struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp);
> > + struct pt_regs *regs = ftrace_get_regs(fregs);
> > int ret = 0;
> >
> > + if (!regs)
> > + return 0;
> > +
> > if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
> > fentry_trace_func(tf, entry_ip, regs);
> > #ifdef CONFIG_PERF_EVENTS
> > diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
> > index 24de0e5ff859..ff607babba18 100644
> > --- a/lib/test_fprobe.c
> > +++ b/lib/test_fprobe.c
> > @@ -40,7 +40,7 @@ static noinline u32 fprobe_selftest_nest_target(u32 value, u32 (*nest)(u32))
> >
> > static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip,
> > unsigned long ret_ip,
> > - struct pt_regs *regs, void *data)
> > + struct ftrace_regs *fregs, void *data)
> > {
> > KUNIT_EXPECT_FALSE(current_test, preemptible());
> > /* This can be called on the fprobe_selftest_target and the fprobe_selftest_target2 */
> > @@ -81,7 +81,7 @@ static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip,
> >
> > static notrace int nest_entry_handler(struct fprobe *fp, unsigned long ip,
> > unsigned long ret_ip,
> > - struct pt_regs *regs, void *data)
> > + struct ftrace_regs *fregs, void *data)
> > {
> > KUNIT_EXPECT_FALSE(current_test, preemptible());
> > return 0;
> > diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c
> > index 64e715e7ed11..1545a1aac616 100644
> > --- a/samples/fprobe/fprobe_example.c
> > +++ b/samples/fprobe/fprobe_example.c
> > @@ -50,7 +50,7 @@ static void show_backtrace(void)
> >
> > static int sample_entry_handler(struct fprobe *fp, unsigned long ip,
> > unsigned long ret_ip,
> > - struct pt_regs *regs, void *data)
> > + struct ftrace_regs *fregs, void *data)
> > {
> > if (use_trace)
> > /*
> >
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 56+ messages in thread
* [PATCH v5 25/34] fprobe: Use ftrace_regs in fprobe exit handler
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (23 preceding siblings ...)
2023-12-18 13:16 ` [PATCH v5 24/34] fprobe: Use ftrace_regs in fprobe entry handler Masami Hiramatsu (Google)
@ 2023-12-18 13:16 ` Masami Hiramatsu (Google)
2023-12-18 13:16 ` [PATCH v5 26/34] tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs Masami Hiramatsu (Google)
` (8 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:16 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Change the fprobe exit handler to use ftrace_regs structure instead of
pt_regs. This also introduce HAVE_PT_REGS_TO_FTRACE_REGS_CAST which means
the ftrace_regs's memory layout is equal to the pt_regs so that those are
able to cast. Fprobe introduces a new dependency with that.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Use ftrace_regs_get_return_value()
Changes from previous series: NOTHING, just forward ported.
---
arch/loongarch/Kconfig | 1 +
arch/s390/Kconfig | 1 +
arch/x86/Kconfig | 1 +
include/linux/fprobe.h | 2 +-
include/linux/ftrace.h | 5 +++++
kernel/trace/Kconfig | 8 ++++++++
kernel/trace/bpf_trace.c | 6 +++++-
kernel/trace/fprobe.c | 3 ++-
kernel/trace/trace_fprobe.c | 6 +++++-
lib/test_fprobe.c | 6 +++---
samples/fprobe/fprobe_example.c | 2 +-
11 files changed, 33 insertions(+), 8 deletions(-)
diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index ee123820a476..b0bd252aefe8 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -108,6 +108,7 @@ config LOONGARCH
select HAVE_DMA_CONTIGUOUS
select HAVE_DYNAMIC_FTRACE
select HAVE_DYNAMIC_FTRACE_WITH_ARGS
+ select HAVE_PT_REGS_TO_FTRACE_REGS_CAST
select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
select HAVE_DYNAMIC_FTRACE_WITH_REGS
select HAVE_EBPF_JIT
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 3bec98d20283..122e9d6e3ad3 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -168,6 +168,7 @@ config S390
select HAVE_DMA_CONTIGUOUS
select HAVE_DYNAMIC_FTRACE
select HAVE_DYNAMIC_FTRACE_WITH_ARGS
+ select HAVE_PT_REGS_TO_FTRACE_REGS_CAST
select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
select HAVE_DYNAMIC_FTRACE_WITH_REGS
select HAVE_EBPF_JIT if HAVE_MARCH_Z196_FEATURES
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 3b955c9e4eb6..1d1da801da7f 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -209,6 +209,7 @@ config X86
select HAVE_DYNAMIC_FTRACE
select HAVE_DYNAMIC_FTRACE_WITH_REGS
select HAVE_DYNAMIC_FTRACE_WITH_ARGS if X86_64
+ select HAVE_PT_REGS_TO_FTRACE_REGS_CAST if X86_64
select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
select HAVE_SAMPLE_FTRACE_DIRECT if X86_64
select HAVE_SAMPLE_FTRACE_DIRECT_MULTI if X86_64
diff --git a/include/linux/fprobe.h b/include/linux/fprobe.h
index 36c0595f7b93..879a30956009 100644
--- a/include/linux/fprobe.h
+++ b/include/linux/fprobe.h
@@ -38,7 +38,7 @@ struct fprobe {
unsigned long ret_ip, struct ftrace_regs *regs,
void *entry_data);
void (*exit_handler)(struct fprobe *fp, unsigned long entry_ip,
- unsigned long ret_ip, struct pt_regs *regs,
+ unsigned long ret_ip, struct ftrace_regs *fregs,
void *entry_data);
};
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index da2a23f5a9ed..a72a2eaec576 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -159,6 +159,11 @@ struct ftrace_regs {
#define ftrace_regs_set_instruction_pointer(fregs, ip) do { } while (0)
#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
+#ifdef CONFIG_HAVE_PT_REGS_TO_FTRACE_REGS_CAST
+
+static_assert(sizeof(struct pt_regs) == sizeof(struct ftrace_regs));
+
+#endif /* CONFIG_HAVE_PT_REGS_TO_FTRACE_REGS_CAST */
static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs)
{
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 805d72ab77c6..1a2544712690 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -60,6 +60,13 @@ config HAVE_DYNAMIC_FTRACE_WITH_ARGS
This allows for use of ftrace_regs_get_argument() and
ftrace_regs_get_stack_pointer().
+config HAVE_PT_REGS_TO_FTRACE_REGS_CAST
+ bool
+ help
+ If this is set, the memory layout of the ftrace_regs data structure
+ is the same as the pt_regs. So the pt_regs is possible to be casted
+ to ftrace_regs.
+
config HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
bool
help
@@ -291,6 +298,7 @@ config FPROBE
bool "Kernel Function Probe (fprobe)"
depends on FUNCTION_TRACER
depends on DYNAMIC_FTRACE_WITH_REGS || DYNAMIC_FTRACE_WITH_ARGS
+ depends on HAVE_PT_REGS_TO_FTRACE_REGS_CAST || !HAVE_DYNAMIC_FTRACE_WITH_ARGS
depends on HAVE_RETHOOK
select RETHOOK
default n
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index d3f8745d8ead..efb792f8f2ea 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2749,10 +2749,14 @@ kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip,
static void
kprobe_multi_link_exit_handler(struct fprobe *fp, unsigned long fentry_ip,
- unsigned long ret_ip, struct pt_regs *regs,
+ unsigned long ret_ip, struct ftrace_regs *fregs,
void *data)
{
struct bpf_kprobe_multi_link *link;
+ struct pt_regs *regs = ftrace_get_regs(fregs);
+
+ if (!regs)
+ return;
link = container_of(fp, struct bpf_kprobe_multi_link, fp);
kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs);
diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index f12569494d8a..688b897626b4 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -124,6 +124,7 @@ static void fprobe_exit_handler(struct rethook_node *rh, void *data,
{
struct fprobe *fp = (struct fprobe *)data;
struct fprobe_rethook_node *fpr;
+ struct ftrace_regs *fregs = (struct ftrace_regs *)regs;
int bit;
if (!fp || fprobe_disabled(fp))
@@ -141,7 +142,7 @@ static void fprobe_exit_handler(struct rethook_node *rh, void *data,
return;
}
- fp->exit_handler(fp, fpr->entry_ip, ret_ip, regs,
+ fp->exit_handler(fp, fpr->entry_ip, ret_ip, fregs,
fp->entry_data_size ? (void *)fpr->data : NULL);
ftrace_test_recursion_unlock(bit);
}
diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
index ef6b36fd05ae..3982626c82e6 100644
--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -341,10 +341,14 @@ static int fentry_dispatcher(struct fprobe *fp, unsigned long entry_ip,
NOKPROBE_SYMBOL(fentry_dispatcher);
static void fexit_dispatcher(struct fprobe *fp, unsigned long entry_ip,
- unsigned long ret_ip, struct pt_regs *regs,
+ unsigned long ret_ip, struct ftrace_regs *fregs,
void *entry_data)
{
struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp);
+ struct pt_regs *regs = ftrace_get_regs(fregs);
+
+ if (!regs)
+ return;
if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
fexit_trace_func(tf, entry_ip, ret_ip, regs);
diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
index ff607babba18..271ce0caeec0 100644
--- a/lib/test_fprobe.c
+++ b/lib/test_fprobe.c
@@ -59,9 +59,9 @@ static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip,
static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip,
unsigned long ret_ip,
- struct pt_regs *regs, void *data)
+ struct ftrace_regs *fregs, void *data)
{
- unsigned long ret = regs_return_value(regs);
+ unsigned long ret = ftrace_regs_get_return_value(fregs);
KUNIT_EXPECT_FALSE(current_test, preemptible());
if (ip != target_ip) {
@@ -89,7 +89,7 @@ static notrace int nest_entry_handler(struct fprobe *fp, unsigned long ip,
static notrace void nest_exit_handler(struct fprobe *fp, unsigned long ip,
unsigned long ret_ip,
- struct pt_regs *regs, void *data)
+ struct ftrace_regs *fregs, void *data)
{
KUNIT_EXPECT_FALSE(current_test, preemptible());
KUNIT_EXPECT_EQ(current_test, ip, target_nest_ip);
diff --git a/samples/fprobe/fprobe_example.c b/samples/fprobe/fprobe_example.c
index 1545a1aac616..d476d1f07538 100644
--- a/samples/fprobe/fprobe_example.c
+++ b/samples/fprobe/fprobe_example.c
@@ -67,7 +67,7 @@ static int sample_entry_handler(struct fprobe *fp, unsigned long ip,
}
static void sample_exit_handler(struct fprobe *fp, unsigned long ip,
- unsigned long ret_ip, struct pt_regs *regs,
+ unsigned long ret_ip, struct ftrace_regs *regs,
void *data)
{
unsigned long rip = ret_ip;
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 26/34] tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (24 preceding siblings ...)
2023-12-18 13:16 ` [PATCH v5 25/34] fprobe: Use ftrace_regs in fprobe exit handler Masami Hiramatsu (Google)
@ 2023-12-18 13:16 ` Masami Hiramatsu (Google)
2023-12-18 13:16 ` [PATCH v5 27/34] tracing: Add ftrace_fill_perf_regs() for perf event Masami Hiramatsu (Google)
` (7 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:16 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Add ftrace_partial_regs() which converts the ftrace_regs to pt_regs.
If the architecture defines its own ftrace_regs, this copies partial
registers to pt_regs and returns it. If not, ftrace_regs is the same as
pt_regs and ftrace_partial_regs() will return ftrace_regs::regs.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Florent Revest <revest@chromium.org>
---
Changes from previous series: NOTHING, just forward ported.
---
arch/arm64/include/asm/ftrace.h | 11 +++++++++++
include/linux/ftrace.h | 17 +++++++++++++++++
2 files changed, 28 insertions(+)
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index efd5dbf74dd6..31051fa2b4d9 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -143,6 +143,17 @@ ftrace_override_function_with_return(struct ftrace_regs *fregs)
fregs->pc = fregs->lr;
}
+static __always_inline struct pt_regs *
+ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
+{
+ memcpy(regs->regs, fregs->regs, sizeof(u64) * 9);
+ regs->sp = fregs->sp;
+ regs->pc = fregs->pc;
+ regs->regs[29] = fregs->fp;
+ regs->regs[30] = fregs->lr;
+ return regs;
+}
+
int ftrace_regs_query_register_offset(const char *name);
int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index a72a2eaec576..515ec804d605 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -173,6 +173,23 @@ static __always_inline struct pt_regs *ftrace_get_regs(struct ftrace_regs *fregs
return arch_ftrace_get_regs(fregs);
}
+#if !defined(CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS) || \
+ defined(CONFIG_HAVE_PT_REGS_TO_FTRACE_REGS_CAST)
+
+static __always_inline struct pt_regs *
+ftrace_partial_regs(struct ftrace_regs *fregs, struct pt_regs *regs)
+{
+ /*
+ * If CONFIG_HAVE_PT_REGS_TO_FTRACE_REGS_CAST=y, ftrace_regs memory
+ * layout is the same as pt_regs. So always returns that address.
+ * Since arch_ftrace_get_regs() will check some members and may return
+ * NULL, we can not use it.
+ */
+ return &fregs->regs;
+}
+
+#endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_PT_REGS_TO_FTRACE_REGS_CAST */
+
/*
* When true, the ftrace_regs_{get,set}_*() functions may be used on fregs.
* Note: this can be true even when ftrace_get_regs() cannot provide a pt_regs.
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 27/34] tracing: Add ftrace_fill_perf_regs() for perf event
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (25 preceding siblings ...)
2023-12-18 13:16 ` [PATCH v5 26/34] tracing: Add ftrace_partial_regs() for converting ftrace_regs to pt_regs Masami Hiramatsu (Google)
@ 2023-12-18 13:16 ` Masami Hiramatsu (Google)
2023-12-18 13:17 ` [PATCH v5 28/34] fprobe: Rewrite fprobe on function-graph tracer Masami Hiramatsu (Google)
` (6 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:16 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Add ftrace_fill_perf_regs() which should be compatible with the
perf_fetch_caller_regs(). In other words, the pt_regs returned from the
ftrace_fill_perf_regs() must satisfy 'user_mode(regs) == false' and can be
used for stack tracing.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes from previous series: NOTHING, just forward ported.
---
arch/arm64/include/asm/ftrace.h | 7 +++++++
arch/powerpc/include/asm/ftrace.h | 7 +++++++
arch/s390/include/asm/ftrace.h | 5 +++++
arch/x86/include/asm/ftrace.h | 7 +++++++
include/linux/ftrace.h | 31 +++++++++++++++++++++++++++++++
5 files changed, 57 insertions(+)
diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h
index 31051fa2b4d9..c1921bdf760b 100644
--- a/arch/arm64/include/asm/ftrace.h
+++ b/arch/arm64/include/asm/ftrace.h
@@ -154,6 +154,13 @@ ftrace_partial_regs(const struct ftrace_regs *fregs, struct pt_regs *regs)
return regs;
}
+#define arch_ftrace_fill_perf_regs(fregs, _regs) do { \
+ (_regs)->pc = (fregs)->pc; \
+ (_regs)->regs[29] = (fregs)->fp; \
+ (_regs)->sp = (fregs)->sp; \
+ (_regs)->pstate = PSR_MODE_EL1h; \
+ } while (0)
+
int ftrace_regs_query_register_offset(const char *name);
int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h
index 7e138e0e3baf..8737a794c764 100644
--- a/arch/powerpc/include/asm/ftrace.h
+++ b/arch/powerpc/include/asm/ftrace.h
@@ -52,6 +52,13 @@ static __always_inline struct pt_regs *arch_ftrace_get_regs(struct ftrace_regs *
return fregs->regs.msr ? &fregs->regs : NULL;
}
+#define arch_ftrace_fill_perf_regs(fregs, _regs) do { \
+ (_regs)->result = 0; \
+ (_regs)->nip = (fregs)->regs.nip; \
+ (_regs)->gpr[1] = (fregs)->regs.gpr[1]; \
+ asm volatile("mfmsr %0" : "=r" ((_regs)->msr)); \
+ } while (0)
+
static __always_inline void
ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
unsigned long ip)
diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h
index 01e775c98425..c2a269c1617c 100644
--- a/arch/s390/include/asm/ftrace.h
+++ b/arch/s390/include/asm/ftrace.h
@@ -97,6 +97,11 @@ ftrace_regs_set_instruction_pointer(struct ftrace_regs *fregs,
#define ftrace_regs_query_register_offset(name) \
regs_query_register_offset(name)
+#define arch_ftrace_fill_perf_regs(fregs, _regs) do { \
+ (_regs)->psw.addr = (fregs)->regs.psw.addr; \
+ (_regs)->gprs[15] = (fregs)->regs.gprs[15]; \
+ } while (0)
+
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
/*
* When an ftrace registered caller is tracing a function that is
diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index a061f8832b20..2e3de45e9746 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -54,6 +54,13 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs)
return &fregs->regs;
}
+#define arch_ftrace_fill_perf_regs(fregs, _regs) do { \
+ (_regs)->ip = (fregs)->regs.ip; \
+ (_regs)->sp = (fregs)->regs.sp; \
+ (_regs)->cs = __KERNEL_CS; \
+ (_regs)->flags = 0; \
+ } while (0)
+
#define ftrace_regs_set_instruction_pointer(fregs, _ip) \
do { (fregs)->regs.ip = (_ip); } while (0)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 515ec804d605..8150edcf8496 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -190,6 +190,37 @@ ftrace_partial_regs(struct ftrace_regs *fregs, struct pt_regs *regs)
#endif /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS || CONFIG_HAVE_PT_REGS_TO_FTRACE_REGS_CAST */
+#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
+
+/*
+ * Please define arch dependent pt_regs which compatible to the
+ * perf_arch_fetch_caller_regs() but based on ftrace_regs.
+ * This requires
+ * - user_mode(_regs) returns false (always kernel mode).
+ * - able to use the _regs for stack trace.
+ */
+#ifndef arch_ftrace_fill_perf_regs
+/* As same as perf_arch_fetch_caller_regs(), do nothing by default */
+#define arch_ftrace_fill_perf_regs(fregs, _regs) do {} while (0)
+#endif
+
+static __always_inline struct pt_regs *
+ftrace_fill_perf_regs(struct ftrace_regs *fregs, struct pt_regs *regs)
+{
+ arch_ftrace_fill_perf_regs(fregs, regs);
+ return regs;
+}
+
+#else /* !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
+
+static __always_inline struct pt_regs *
+ftrace_fill_perf_regs(struct ftrace_regs *fregs, struct pt_regs *regs)
+{
+ return &fregs->regs;
+}
+
+#endif
+
/*
* When true, the ftrace_regs_{get,set}_*() functions may be used on fregs.
* Note: this can be true even when ftrace_get_regs() cannot provide a pt_regs.
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 28/34] fprobe: Rewrite fprobe on function-graph tracer
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (26 preceding siblings ...)
2023-12-18 13:16 ` [PATCH v5 27/34] tracing: Add ftrace_fill_perf_regs() for perf event Masami Hiramatsu (Google)
@ 2023-12-18 13:17 ` Masami Hiramatsu (Google)
2023-12-19 14:39 ` Jiri Olsa
2023-12-18 13:17 ` [PATCH v5 29/34] tracing/fprobe: Remove nr_maxactive from fprobe Masami Hiramatsu (Google)
` (5 subsequent siblings)
33 siblings, 1 reply; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:17 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Rewrite fprobe implementation on function-graph tracer.
Major API changes are:
- 'nr_maxactive' field is deprecated.
- This depends on CONFIG_DYNAMIC_FTRACE_WITH_ARGS or
!CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS, and
CONFIG_HAVE_FUNCTION_GRAPH_FREGS. So currently works only
on x86_64.
- Currently the entry size is limited in 15 * sizeof(long).
- If there is too many fprobe exit handler set on the same
function, it will fail to probe.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v3:
- Update for new reserve_data/retrieve_data API.
- Fix internal push/pop on fgraph data logic so that it can
correctly save/restore the returning fprobes.
Changes in v2:
- Add more lockdep_assert_held(fprobe_mutex)
- Use READ_ONCE() and WRITE_ONCE() for fprobe_hlist_node::fp.
- Add NOKPROBE_SYMBOL() for the functions which is called from
entry/exit callback.
---
include/linux/fprobe.h | 54 +++-
kernel/trace/Kconfig | 8 -
kernel/trace/fprobe.c | 632 ++++++++++++++++++++++++++++++++++--------------
lib/test_fprobe.c | 45 ---
4 files changed, 494 insertions(+), 245 deletions(-)
diff --git a/include/linux/fprobe.h b/include/linux/fprobe.h
index 879a30956009..08b37b0d1d05 100644
--- a/include/linux/fprobe.h
+++ b/include/linux/fprobe.h
@@ -5,32 +5,56 @@
#include <linux/compiler.h>
#include <linux/ftrace.h>
-#include <linux/rethook.h>
+#include <linux/rcupdate.h>
+#include <linux/refcount.h>
+#include <linux/slab.h>
+
+struct fprobe;
+
+/**
+ * strcut fprobe_hlist_node - address based hash list node for fprobe.
+ *
+ * @hlist: The hlist node for address search hash table.
+ * @addr: The address represented by this.
+ * @fp: The fprobe which owns this.
+ */
+struct fprobe_hlist_node {
+ struct hlist_node hlist;
+ unsigned long addr;
+ struct fprobe *fp;
+};
+
+/**
+ * struct fprobe_hlist - hash list nodes for fprobe.
+ *
+ * @hlist: The hlist node for existence checking hash table.
+ * @rcu: rcu_head for RCU deferred release.
+ * @fp: The fprobe which owns this fprobe_hlist.
+ * @size: The size of @array.
+ * @array: The fprobe_hlist_node for each address to probe.
+ */
+struct fprobe_hlist {
+ struct hlist_node hlist;
+ struct rcu_head rcu;
+ struct fprobe *fp;
+ int size;
+ struct fprobe_hlist_node array[];
+};
/**
* struct fprobe - ftrace based probe.
- * @ops: The ftrace_ops.
+ *
* @nmissed: The counter for missing events.
* @flags: The status flag.
- * @rethook: The rethook data structure. (internal data)
* @entry_data_size: The private data storage size.
- * @nr_maxactive: The max number of active functions.
+ * @nr_maxactive: The max number of active functions. (*deprecated)
* @entry_handler: The callback function for function entry.
* @exit_handler: The callback function for function exit.
+ * @hlist_array: The fprobe_hlist for fprobe search from IP hash table.
*/
struct fprobe {
-#ifdef CONFIG_FUNCTION_TRACER
- /*
- * If CONFIG_FUNCTION_TRACER is not set, CONFIG_FPROBE is disabled too.
- * But user of fprobe may keep embedding the struct fprobe on their own
- * code. To avoid build error, this will keep the fprobe data structure
- * defined here, but remove ftrace_ops data structure.
- */
- struct ftrace_ops ops;
-#endif
unsigned long nmissed;
unsigned int flags;
- struct rethook *rethook;
size_t entry_data_size;
int nr_maxactive;
@@ -40,6 +64,8 @@ struct fprobe {
void (*exit_handler)(struct fprobe *fp, unsigned long entry_ip,
unsigned long ret_ip, struct ftrace_regs *fregs,
void *entry_data);
+
+ struct fprobe_hlist *hlist_array;
};
/* This fprobe is soft-disabled. */
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 1a2544712690..11a96275b68c 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -296,11 +296,9 @@ config DYNAMIC_FTRACE_WITH_ARGS
config FPROBE
bool "Kernel Function Probe (fprobe)"
- depends on FUNCTION_TRACER
- depends on DYNAMIC_FTRACE_WITH_REGS || DYNAMIC_FTRACE_WITH_ARGS
- depends on HAVE_PT_REGS_TO_FTRACE_REGS_CAST || !HAVE_DYNAMIC_FTRACE_WITH_ARGS
- depends on HAVE_RETHOOK
- select RETHOOK
+ depends on FUNCTION_GRAPH_TRACER
+ depends on HAVE_FUNCTION_GRAPH_FREGS
+ depends on DYNAMIC_FTRACE_WITH_ARGS || !HAVE_DYNAMIC_FTRACE_WITH_ARGS
default n
help
This option enables kernel function probe (fprobe) based on ftrace.
diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index 688b897626b4..53e681c2458b 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -8,98 +8,193 @@
#include <linux/fprobe.h>
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
-#include <linux/rethook.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/sort.h>
#include "trace.h"
-struct fprobe_rethook_node {
- struct rethook_node node;
- unsigned long entry_ip;
- unsigned long entry_parent_ip;
- char data[];
-};
+#define FPROBE_IP_HASH_BITS 8
+#define FPROBE_IP_TABLE_SIZE (1 << FPROBE_IP_HASH_BITS)
-static inline void __fprobe_handler(unsigned long ip, unsigned long parent_ip,
- struct ftrace_ops *ops, struct ftrace_regs *fregs)
-{
- struct fprobe_rethook_node *fpr;
- struct rethook_node *rh = NULL;
- struct fprobe *fp;
- void *entry_data = NULL;
- int ret = 0;
+#define FPROBE_HASH_BITS 6
+#define FPROBE_TABLE_SIZE (1 << FPROBE_HASH_BITS)
- fp = container_of(ops, struct fprobe, ops);
+/*
+ * fprobe_table: hold 'fprobe_hlist::hlist' for checking the fprobe still
+ * exists. The key is the address of fprobe instance.
+ * fprobe_ip_table: hold 'fprobe_hlist::array[*]' for searching the fprobe
+ * instance related to the funciton address. The key is the ftrace IP
+ * address.
+ *
+ * When unregistering the fprobe, fprobe_hlist::fp and fprobe_hlist::array[*].fp
+ * are set NULL and delete those from both hash tables (by hlist_del_rcu).
+ * After an RCU grace period, the fprobe_hlist itself will be released.
+ *
+ * fprobe_table and fprobe_ip_table can be accessed from either
+ * - Normal hlist traversal and RCU add/del under 'fprobe_mutex' is held.
+ * - RCU hlist traversal under disabling preempt
+ */
+static struct hlist_head fprobe_table[FPROBE_TABLE_SIZE];
+static struct hlist_head fprobe_ip_table[FPROBE_IP_TABLE_SIZE];
+static DEFINE_MUTEX(fprobe_mutex);
- if (fp->exit_handler) {
- rh = rethook_try_get(fp->rethook);
- if (!rh) {
- fp->nmissed++;
- return;
- }
- fpr = container_of(rh, struct fprobe_rethook_node, node);
- fpr->entry_ip = ip;
- fpr->entry_parent_ip = parent_ip;
- if (fp->entry_data_size)
- entry_data = fpr->data;
+/*
+ * Find first fprobe in the hlist. It will be iterated twice in the entry
+ * probe, once for correcting the total required size, the second time is
+ * calling back the user handlers.
+ * Thus the hlist in the fprobe_table must be sorted and new probe needs to
+ * be added *before* the first fprobe.
+ */
+static struct fprobe_hlist_node *find_first_fprobe_node(unsigned long ip)
+{
+ struct fprobe_hlist_node *node;
+ struct hlist_head *head;
+
+ head = &fprobe_ip_table[hash_ptr((void *)ip, FPROBE_IP_HASH_BITS)];
+ hlist_for_each_entry_rcu(node, head, hlist,
+ lockdep_is_held(&fprobe_mutex)) {
+ if (node->addr == ip)
+ return node;
}
+ return NULL;
+}
+NOKPROBE_SYMBOL(find_first_fprobe_node);
- if (fp->entry_handler)
- ret = fp->entry_handler(fp, ip, parent_ip, fregs, entry_data);
+/* Node insertion and deletion requires the fprobe_mutex */
+static void insert_fprobe_node(struct fprobe_hlist_node *node)
+{
+ unsigned long ip = node->addr;
+ struct fprobe_hlist_node *next;
+ struct hlist_head *head;
- /* If entry_handler returns !0, nmissed is not counted. */
- if (rh) {
- if (ret)
- rethook_recycle(rh);
- else
- rethook_hook(rh, ftrace_get_regs(fregs), true);
+ lockdep_assert_held(&fprobe_mutex);
+
+ next = find_first_fprobe_node(ip);
+ if (next) {
+ hlist_add_before_rcu(&node->hlist, &next->hlist);
+ return;
}
+ head = &fprobe_ip_table[hash_ptr((void *)ip, FPROBE_IP_HASH_BITS)];
+ hlist_add_head_rcu(&node->hlist, head);
}
-static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
- struct ftrace_ops *ops, struct ftrace_regs *fregs)
+/* Return true if there are synonims */
+static bool delete_fprobe_node(struct fprobe_hlist_node *node)
{
- struct fprobe *fp;
- int bit;
+ lockdep_assert_held(&fprobe_mutex);
- fp = container_of(ops, struct fprobe, ops);
- if (fprobe_disabled(fp))
- return;
+ WRITE_ONCE(node->fp, NULL);
+ hlist_del_rcu(&node->hlist);
+ return !!find_first_fprobe_node(node->addr);
+}
- /* recursion detection has to go before any traceable function and
- * all functions before this point should be marked as notrace
- */
- bit = ftrace_test_recursion_trylock(ip, parent_ip);
- if (bit < 0) {
- fp->nmissed++;
- return;
+/* Check existence of the fprobe */
+static bool is_fprobe_still_exist(struct fprobe *fp)
+{
+ struct hlist_head *head;
+ struct fprobe_hlist *fph;
+
+ head = &fprobe_table[hash_ptr(fp, FPROBE_HASH_BITS)];
+ hlist_for_each_entry_rcu(fph, head, hlist,
+ lockdep_is_held(&fprobe_mutex)) {
+ if (fph->fp == fp)
+ return true;
}
- __fprobe_handler(ip, parent_ip, ops, fregs);
- ftrace_test_recursion_unlock(bit);
+ return false;
+}
+NOKPROBE_SYMBOL(is_fprobe_still_exist);
+
+static int add_fprobe_hash(struct fprobe *fp)
+{
+ struct fprobe_hlist *fph = fp->hlist_array;
+ struct hlist_head *head;
+
+ lockdep_assert_held(&fprobe_mutex);
+ if (WARN_ON_ONCE(!fph))
+ return -EINVAL;
+
+ if (is_fprobe_still_exist(fp))
+ return -EEXIST;
+
+ head = &fprobe_table[hash_ptr(fp, FPROBE_HASH_BITS)];
+ hlist_add_head_rcu(&fp->hlist_array->hlist, head);
+ return 0;
}
-NOKPROBE_SYMBOL(fprobe_handler);
-static void fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip,
- struct ftrace_ops *ops, struct ftrace_regs *fregs)
+static int del_fprobe_hash(struct fprobe *fp)
{
- struct fprobe *fp;
- int bit;
+ struct fprobe_hlist *fph = fp->hlist_array;
- fp = container_of(ops, struct fprobe, ops);
- if (fprobe_disabled(fp))
- return;
+ lockdep_assert_held(&fprobe_mutex);
- /* recursion detection has to go before any traceable function and
- * all functions called before this point should be marked as notrace
- */
- bit = ftrace_test_recursion_trylock(ip, parent_ip);
- if (bit < 0) {
- fp->nmissed++;
- return;
+ if (WARN_ON_ONCE(!fph))
+ return -EINVAL;
+
+ if (!is_fprobe_still_exist(fp))
+ return -ENOENT;
+
+ fph->fp = NULL;
+ hlist_del_rcu(&fph->hlist);
+ return 0;
+}
+
+/* The entry data size is 4 bits (=16) * sizeof(long) in maximum */
+#define FPROBE_HEADER_SIZE_BITS 4
+#define MAX_FPROBE_DATA_SIZE_WORD ((1L << FPROBE_HEADER_SIZE_BITS) - 1)
+#define MAX_FPROBE_DATA_SIZE (MAX_FPROBE_DATA_SIZE_WORD * sizeof(long))
+#define FPROBE_HEADER_PTR_BITS (BITS_PER_LONG - FPROBE_HEADER_SIZE_BITS)
+#define FPROBE_HEADER_PTR_MASK GENMASK(FPROBE_HEADER_PTR_BITS - 1, 0)
+#define FPROBE_HEADER_SIZE sizeof(unsigned long)
+
+static inline unsigned long encode_fprobe_header(struct fprobe *fp, int size_words)
+{
+ if (WARN_ON_ONCE(size_words > MAX_FPROBE_DATA_SIZE_WORD ||
+ ((unsigned long)fp & ~FPROBE_HEADER_PTR_MASK) !=
+ ~FPROBE_HEADER_PTR_MASK)) {
+ return 0;
}
+ return ((unsigned long)size_words << FPROBE_HEADER_PTR_BITS) |
+ ((unsigned long)fp & FPROBE_HEADER_PTR_MASK);
+}
+
+/* Return reserved data size in words */
+static inline int decode_fprobe_header(unsigned long val, struct fprobe **fp)
+{
+ unsigned long ptr;
+
+ ptr = (val & FPROBE_HEADER_PTR_MASK) | ~FPROBE_HEADER_PTR_MASK;
+ if (fp)
+ *fp = (struct fprobe *)ptr;
+ return val >> FPROBE_HEADER_PTR_BITS;
+}
+
+/*
+ * fprobe shadow stack management:
+ * Since fprobe shares a single fgraph_ops, it needs to share the stack entry
+ * among the probes on the same function exit. Note that a new probe can be
+ * registered before a target function is returning, we can not use the hash
+ * table to find the corresponding probes. Thus the probe address is stored on
+ * the shadow stack with its entry data size.
+ *
+ */
+static inline int __fprobe_handler(unsigned long ip, unsigned long parent_ip,
+ struct fprobe *fp, struct ftrace_regs *fregs,
+ void *data)
+{
+ if (!fp->entry_handler)
+ return 0;
+
+ return fp->entry_handler(fp, ip, parent_ip, fregs, data);
+}
+static inline int __fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip,
+ struct fprobe *fp, struct ftrace_regs *fregs,
+ void *data)
+{
+ int ret;
/*
* This user handler is shared with other kprobes and is not expected to be
* called recursively. So if any other kprobe handler is running, this will
@@ -108,45 +203,180 @@ static void fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip,
*/
if (unlikely(kprobe_running())) {
fp->nmissed++;
- goto recursion_unlock;
+ return 0;
}
kprobe_busy_begin();
- __fprobe_handler(ip, parent_ip, ops, fregs);
+ ret = __fprobe_handler(ip, parent_ip, fp, fregs, data);
kprobe_busy_end();
-
-recursion_unlock:
- ftrace_test_recursion_unlock(bit);
+ return ret;
}
-static void fprobe_exit_handler(struct rethook_node *rh, void *data,
- unsigned long ret_ip, struct pt_regs *regs)
+static int fprobe_entry(unsigned long func, unsigned long ret_ip,
+ struct ftrace_regs *fregs, struct fgraph_ops *gops)
{
- struct fprobe *fp = (struct fprobe *)data;
- struct fprobe_rethook_node *fpr;
- struct ftrace_regs *fregs = (struct ftrace_regs *)regs;
- int bit;
+ struct fprobe_hlist_node *node, *first;
+ unsigned long *fgraph_data = NULL;
+ unsigned long header;
+ int reserved_words;
+ struct fprobe *fp;
+ int used, ret;
- if (!fp || fprobe_disabled(fp))
- return;
+ if (WARN_ON_ONCE(!fregs))
+ return 0;
- fpr = container_of(rh, struct fprobe_rethook_node, node);
+ first = node = find_first_fprobe_node(func);
+ if (unlikely(!first))
+ return 0;
+
+ reserved_words = 0;
+ hlist_for_each_entry_from_rcu(node, hlist) {
+ if (node->addr != func)
+ break;
+ fp = READ_ONCE(node->fp);
+ if (!fp || !fp->exit_handler)
+ continue;
+ /*
+ * Since fprobe can be enabled until the next loop, we ignore the
+ * fprobe's disabled flag in this loop.
+ */
+ reserved_words +=
+ DIV_ROUND_UP(fp->entry_data_size, sizeof(long)) + 1;
+ }
+ node = first;
+ if (reserved_words) {
+ fgraph_data = fgraph_reserve_data(gops->idx, reserved_words * sizeof(long));
+ if (unlikely(!fgraph_data)) {
+ hlist_for_each_entry_from_rcu(node, hlist) {
+ if (node->addr != func)
+ break;
+ fp = READ_ONCE(node->fp);
+ if (fp && !fprobe_disabled(fp))
+ fp->nmissed++;
+ }
+ return 0;
+ }
+ }
/*
- * we need to assure no calls to traceable functions in-between the
- * end of fprobe_handler and the beginning of fprobe_exit_handler.
+ * TODO: recursion detection has been done in the fgraph. Thus we need
+ * to add a callback to increment missed counter.
*/
- bit = ftrace_test_recursion_trylock(fpr->entry_ip, fpr->entry_parent_ip);
- if (bit < 0) {
- fp->nmissed++;
+ used = 0;
+ hlist_for_each_entry_from_rcu(node, hlist) {
+ void *data;
+
+ if (node->addr != func)
+ break;
+ fp = READ_ONCE(node->fp);
+ if (!fp || fprobe_disabled(fp))
+ continue;
+
+ if (fp->entry_data_size && fp->exit_handler)
+ data = fgraph_data + used + 1;
+ else
+ data = NULL;
+
+ if (fprobe_shared_with_kprobes(fp))
+ ret = __fprobe_kprobe_handler(func, ret_ip, fp, fregs, data);
+ else
+ ret = __fprobe_handler(func, ret_ip, fp, fregs, data);
+ /* If entry_handler returns !0, nmissed is not counted but skips exit_handler. */
+ if (!ret && fp->exit_handler) {
+ int size_words = DIV_ROUND_UP(fp->entry_data_size, sizeof(long));
+
+ header = encode_fprobe_header(fp, size_words);
+ if (likely(header)) {
+ fgraph_data[used] = header;
+ used += size_words + 1;
+ }
+ }
+ }
+ if (used < reserved_words)
+ memset(fgraph_data + used, 0, reserved_words - used);
+
+ /* If any exit_handler is set, data must be used. */
+ return used != 0;
+}
+NOKPROBE_SYMBOL(fprobe_entry);
+
+static void fprobe_return(unsigned long func, unsigned long ret_ip,
+ struct ftrace_regs *fregs, struct fgraph_ops *gops)
+{
+ unsigned long *fgraph_data = NULL;
+ unsigned long val;
+ struct fprobe *fp;
+ int size, curr;
+ int size_words;
+
+ fgraph_data = (unsigned long *)fgraph_retrieve_data(gops->idx, &size);
+ if (!fgraph_data)
+ return;
+ size_words = DIV_ROUND_UP(size, sizeof(long));
+
+ preempt_disable();
+
+ curr = 0;
+ while (size_words > curr) {
+ val = fgraph_data[curr++];
+ if (!val)
+ break;
+
+ size = decode_fprobe_header(val, &fp);
+ if (fp && is_fprobe_still_exist(fp) && !fprobe_disabled(fp)) {
+ if (WARN_ON_ONCE(curr + size > size_words))
+ break;
+ fp->exit_handler(fp, func, ret_ip, fregs,
+ size ? fgraph_data + curr : NULL);
+ }
+ curr += size + 1;
+ }
+ preempt_enable();
+}
+NOKPROBE_SYMBOL(fprobe_return);
+
+static struct fgraph_ops fprobe_graph_ops = {
+ .entryregfunc = fprobe_entry,
+ .retregfunc = fprobe_return,
+};
+static int fprobe_graph_active;
+
+/* Add @addrs to the ftrace filter and register fgraph if needed. */
+static int fprobe_graph_add_ips(unsigned long *addrs, int num)
+{
+ int ret;
+
+ lockdep_assert_held(&fprobe_mutex);
+
+ ret = ftrace_set_filter_ips(&fprobe_graph_ops.ops, addrs, num, 0, 0);
+ if (ret)
+ return ret;
+
+ if (!fprobe_graph_active) {
+ ret = register_ftrace_graph(&fprobe_graph_ops);
+ if (WARN_ON_ONCE(ret)) {
+ ftrace_free_filter(&fprobe_graph_ops.ops);
+ return ret;
+ }
+ }
+ fprobe_graph_active++;
+ return 0;
+}
+
+/* Remove @addrs from the ftrace filter and unregister fgraph if possible. */
+static void fprobe_graph_remove_ips(unsigned long *addrs, int num)
+{
+ lockdep_assert_held(&fprobe_mutex);
+
+ fprobe_graph_active--;
+ if (!fprobe_graph_active) {
+ /* Q: should we unregister it ? */
+ unregister_ftrace_graph(&fprobe_graph_ops);
return;
}
- fp->exit_handler(fp, fpr->entry_ip, ret_ip, fregs,
- fp->entry_data_size ? (void *)fpr->data : NULL);
- ftrace_test_recursion_unlock(bit);
+ ftrace_set_filter_ips(&fprobe_graph_ops.ops, addrs, num, 1, 0);
}
-NOKPROBE_SYMBOL(fprobe_exit_handler);
static int symbols_cmp(const void *a, const void *b)
{
@@ -176,55 +406,97 @@ static unsigned long *get_ftrace_locations(const char **syms, int num)
return ERR_PTR(-ENOENT);
}
-static void fprobe_init(struct fprobe *fp)
-{
- fp->nmissed = 0;
- if (fprobe_shared_with_kprobes(fp))
- fp->ops.func = fprobe_kprobe_handler;
- else
- fp->ops.func = fprobe_handler;
- fp->ops.flags |= FTRACE_OPS_FL_SAVE_ARGS;
-}
+struct filter_match_data {
+ const char *filter;
+ const char *notfilter;
+ size_t index;
+ size_t size;
+ unsigned long *addrs;
+};
-static int fprobe_init_rethook(struct fprobe *fp, int num)
+static int filter_match_callback(void *data, const char *name, unsigned long addr)
{
- int size;
+ struct filter_match_data *match = data;
- if (num <= 0)
- return -EINVAL;
+ if (!glob_match(match->filter, name) ||
+ (match->notfilter && glob_match(match->notfilter, name)))
+ return 0;
- if (!fp->exit_handler) {
- fp->rethook = NULL;
+ if (!ftrace_location(addr))
return 0;
- }
- /* Initialize rethook if needed */
- if (fp->nr_maxactive)
- size = fp->nr_maxactive;
- else
- size = num * num_possible_cpus() * 2;
- if (size <= 0)
- return -EINVAL;
+ if (match->addrs)
+ match->addrs[match->index] = addr;
- /* Initialize rethook */
- fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler,
- sizeof(struct fprobe_rethook_node), size);
- if (IS_ERR(fp->rethook))
- return PTR_ERR(fp->rethook);
+ match->index++;
+ return match->index == match->size;
+}
- return 0;
+/*
+ * Make IP list from the filter/no-filter glob patterns.
+ * Return the number of matched symbols, or -ENOENT.
+ */
+static int ip_list_from_filter(const char *filter, const char *notfilter,
+ unsigned long *addrs, size_t size)
+{
+ struct filter_match_data match = { .filter = filter, .notfilter = notfilter,
+ .index = 0, .size = size, .addrs = addrs};
+ int ret;
+
+ ret = kallsyms_on_each_symbol(filter_match_callback, &match);
+ if (ret < 0)
+ return ret;
+ ret = module_kallsyms_on_each_symbol(NULL, filter_match_callback, &match);
+ if (ret < 0)
+ return ret;
+
+ return match.index ?: -ENOENT;
}
static void fprobe_fail_cleanup(struct fprobe *fp)
{
- if (!IS_ERR_OR_NULL(fp->rethook)) {
- /* Don't need to cleanup rethook->handler because this is not used. */
- rethook_free(fp->rethook);
- fp->rethook = NULL;
+ kfree(fp->hlist_array);
+ fp->hlist_array = NULL;
+}
+
+/* Initialize the fprobe data structure. */
+static int fprobe_init(struct fprobe *fp, unsigned long *addrs, int num)
+{
+ struct fprobe_hlist *hlist_array;
+ unsigned long addr;
+ int size, i;
+
+ if (!fp || !addrs || num <= 0)
+ return -EINVAL;
+
+ size = ALIGN(fp->entry_data_size, sizeof(long));
+ if (size > MAX_FPROBE_DATA_SIZE)
+ return -E2BIG;
+ fp->entry_data_size = size;
+
+ hlist_array = kzalloc(struct_size(hlist_array, array, num), GFP_KERNEL);
+ if (!hlist_array)
+ return -ENOMEM;
+
+ fp->nmissed = 0;
+
+ hlist_array->size = num;
+ fp->hlist_array = hlist_array;
+ hlist_array->fp = fp;
+ for (i = 0; i < num; i++) {
+ hlist_array->array[i].fp = fp;
+ addr = ftrace_location(addrs[i]);
+ if (!addr) {
+ fprobe_fail_cleanup(fp);
+ return -ENOENT;
+ }
+ hlist_array->array[i].addr = addr;
}
- ftrace_free_filter(&fp->ops);
+ return 0;
}
+#define FPROBE_IPS_MAX INT_MAX
+
/**
* register_fprobe() - Register fprobe to ftrace by pattern.
* @fp: A fprobe data structure to be registered.
@@ -238,46 +510,24 @@ static void fprobe_fail_cleanup(struct fprobe *fp)
*/
int register_fprobe(struct fprobe *fp, const char *filter, const char *notfilter)
{
- struct ftrace_hash *hash;
- unsigned char *str;
- int ret, len;
+ unsigned long *addrs;
+ int ret;
if (!fp || !filter)
return -EINVAL;
- fprobe_init(fp);
-
- len = strlen(filter);
- str = kstrdup(filter, GFP_KERNEL);
- ret = ftrace_set_filter(&fp->ops, str, len, 0);
- kfree(str);
- if (ret)
+ ret = ip_list_from_filter(filter, notfilter, NULL, FPROBE_IPS_MAX);
+ if (ret < 0)
return ret;
- if (notfilter) {
- len = strlen(notfilter);
- str = kstrdup(notfilter, GFP_KERNEL);
- ret = ftrace_set_notrace(&fp->ops, str, len, 0);
- kfree(str);
- if (ret)
- goto out;
- }
-
- /* TODO:
- * correctly calculate the total number of filtered symbols
- * from both filter and notfilter.
- */
- hash = rcu_access_pointer(fp->ops.local_hash.filter_hash);
- if (WARN_ON_ONCE(!hash))
- goto out;
-
- ret = fprobe_init_rethook(fp, (int)hash->count);
- if (!ret)
- ret = register_ftrace_function(&fp->ops);
+ addrs = kcalloc(ret, sizeof(unsigned long), GFP_KERNEL);
+ if (!addrs)
+ return -ENOMEM;
+ ret = ip_list_from_filter(filter, notfilter, addrs, ret);
+ if (ret > 0)
+ ret = register_fprobe_ips(fp, addrs, ret);
-out:
- if (ret)
- fprobe_fail_cleanup(fp);
+ kfree(addrs);
return ret;
}
EXPORT_SYMBOL_GPL(register_fprobe);
@@ -285,7 +535,7 @@ EXPORT_SYMBOL_GPL(register_fprobe);
/**
* register_fprobe_ips() - Register fprobe to ftrace by address.
* @fp: A fprobe data structure to be registered.
- * @addrs: An array of target ftrace location addresses.
+ * @addrs: An array of target function address.
* @num: The number of entries of @addrs.
*
* Register @fp to ftrace for enabling the probe on the address given by @addrs.
@@ -297,23 +547,27 @@ EXPORT_SYMBOL_GPL(register_fprobe);
*/
int register_fprobe_ips(struct fprobe *fp, unsigned long *addrs, int num)
{
- int ret;
-
- if (!fp || !addrs || num <= 0)
- return -EINVAL;
-
- fprobe_init(fp);
+ struct fprobe_hlist *hlist_array;
+ int ret, i;
- ret = ftrace_set_filter_ips(&fp->ops, addrs, num, 0, 0);
+ ret = fprobe_init(fp, addrs, num);
if (ret)
return ret;
- ret = fprobe_init_rethook(fp, num);
- if (!ret)
- ret = register_ftrace_function(&fp->ops);
+ mutex_lock(&fprobe_mutex);
+
+ hlist_array = fp->hlist_array;
+ ret = fprobe_graph_add_ips(addrs, num);
+ if (!ret) {
+ add_fprobe_hash(fp);
+ for (i = 0; i < hlist_array->size; i++)
+ insert_fprobe_node(&hlist_array->array[i]);
+ }
+ mutex_unlock(&fprobe_mutex);
if (ret)
fprobe_fail_cleanup(fp);
+
return ret;
}
EXPORT_SYMBOL_GPL(register_fprobe_ips);
@@ -351,14 +605,13 @@ EXPORT_SYMBOL_GPL(register_fprobe_syms);
bool fprobe_is_registered(struct fprobe *fp)
{
- if (!fp || (fp->ops.saved_func != fprobe_handler &&
- fp->ops.saved_func != fprobe_kprobe_handler))
+ if (!fp || !fp->hlist_array)
return false;
return true;
}
/**
- * unregister_fprobe() - Unregister fprobe from ftrace
+ * unregister_fprobe() - Unregister fprobe.
* @fp: A fprobe data structure to be unregistered.
*
* Unregister fprobe (and remove ftrace hooks from the function entries).
@@ -367,23 +620,40 @@ bool fprobe_is_registered(struct fprobe *fp)
*/
int unregister_fprobe(struct fprobe *fp)
{
- int ret;
+ struct fprobe_hlist *hlist_array;
+ unsigned long *addrs = NULL;
+ int ret = 0, i, count;
- if (!fprobe_is_registered(fp))
- return -EINVAL;
+ mutex_lock(&fprobe_mutex);
+ if (!fp || !is_fprobe_still_exist(fp)) {
+ ret = -EINVAL;
+ goto out;
+ }
- if (!IS_ERR_OR_NULL(fp->rethook))
- rethook_stop(fp->rethook);
+ hlist_array = fp->hlist_array;
+ addrs = kcalloc(hlist_array->size, sizeof(unsigned long), GFP_KERNEL);
+ if (!addrs) {
+ ret = -ENOMEM; /* TODO: Fallback to one-by-one loop */
+ goto out;
+ }
- ret = unregister_ftrace_function(&fp->ops);
- if (ret < 0)
- return ret;
+ /* Remove non-synonim ips from table and hash */
+ count = 0;
+ for (i = 0; i < hlist_array->size; i++) {
+ if (!delete_fprobe_node(&hlist_array->array[i]))
+ addrs[count++] = hlist_array->array[i].addr;
+ }
+ del_fprobe_hash(fp);
- if (!IS_ERR_OR_NULL(fp->rethook))
- rethook_free(fp->rethook);
+ fprobe_graph_remove_ips(addrs, count);
- ftrace_free_filter(&fp->ops);
+ kfree_rcu(hlist_array, rcu);
+ fp->hlist_array = NULL;
+out:
+ mutex_unlock(&fprobe_mutex);
+
+ kfree(addrs);
return ret;
}
EXPORT_SYMBOL_GPL(unregister_fprobe);
diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
index 271ce0caeec0..cf92111b5c79 100644
--- a/lib/test_fprobe.c
+++ b/lib/test_fprobe.c
@@ -17,10 +17,8 @@ static u32 rand1, entry_val, exit_val;
/* Use indirect calls to avoid inlining the target functions */
static u32 (*target)(u32 value);
static u32 (*target2)(u32 value);
-static u32 (*target_nest)(u32 value, u32 (*nest)(u32));
static unsigned long target_ip;
static unsigned long target2_ip;
-static unsigned long target_nest_ip;
static int entry_return_value;
static noinline u32 fprobe_selftest_target(u32 value)
@@ -33,11 +31,6 @@ static noinline u32 fprobe_selftest_target2(u32 value)
return (value / div_factor) + 1;
}
-static noinline u32 fprobe_selftest_nest_target(u32 value, u32 (*nest)(u32))
-{
- return nest(value + 2);
-}
-
static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip,
unsigned long ret_ip,
struct ftrace_regs *fregs, void *data)
@@ -79,22 +72,6 @@ static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip,
KUNIT_EXPECT_NULL(current_test, data);
}
-static notrace int nest_entry_handler(struct fprobe *fp, unsigned long ip,
- unsigned long ret_ip,
- struct ftrace_regs *fregs, void *data)
-{
- KUNIT_EXPECT_FALSE(current_test, preemptible());
- return 0;
-}
-
-static notrace void nest_exit_handler(struct fprobe *fp, unsigned long ip,
- unsigned long ret_ip,
- struct ftrace_regs *fregs, void *data)
-{
- KUNIT_EXPECT_FALSE(current_test, preemptible());
- KUNIT_EXPECT_EQ(current_test, ip, target_nest_ip);
-}
-
/* Test entry only (no rethook) */
static void test_fprobe_entry(struct kunit *test)
{
@@ -191,25 +168,6 @@ static void test_fprobe_data(struct kunit *test)
KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp));
}
-/* Test nr_maxactive */
-static void test_fprobe_nest(struct kunit *test)
-{
- static const char *syms[] = {"fprobe_selftest_target", "fprobe_selftest_nest_target"};
- struct fprobe fp = {
- .entry_handler = nest_entry_handler,
- .exit_handler = nest_exit_handler,
- .nr_maxactive = 1,
- };
-
- current_test = test;
- KUNIT_EXPECT_EQ(test, 0, register_fprobe_syms(&fp, syms, 2));
-
- target_nest(rand1, target);
- KUNIT_EXPECT_EQ(test, 1, fp.nmissed);
-
- KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp));
-}
-
static void test_fprobe_skip(struct kunit *test)
{
struct fprobe fp = {
@@ -247,10 +205,8 @@ static int fprobe_test_init(struct kunit *test)
rand1 = get_random_u32_above(div_factor);
target = fprobe_selftest_target;
target2 = fprobe_selftest_target2;
- target_nest = fprobe_selftest_nest_target;
target_ip = get_ftrace_location(target);
target2_ip = get_ftrace_location(target2);
- target_nest_ip = get_ftrace_location(target_nest);
return 0;
}
@@ -260,7 +216,6 @@ static struct kunit_case fprobe_testcases[] = {
KUNIT_CASE(test_fprobe),
KUNIT_CASE(test_fprobe_syms),
KUNIT_CASE(test_fprobe_data),
- KUNIT_CASE(test_fprobe_nest),
KUNIT_CASE(test_fprobe_skip),
{}
};
^ permalink raw reply related [flat|nested] 56+ messages in thread* Re: [PATCH v5 28/34] fprobe: Rewrite fprobe on function-graph tracer
2023-12-18 13:17 ` [PATCH v5 28/34] fprobe: Rewrite fprobe on function-graph tracer Masami Hiramatsu (Google)
@ 2023-12-19 14:39 ` Jiri Olsa
2023-12-20 1:00 ` Masami Hiramatsu
0 siblings, 1 reply; 56+ messages in thread
From: Jiri Olsa @ 2023-12-19 14:39 UTC (permalink / raw)
To: Masami Hiramatsu (Google)
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Arnaldo Carvalho de Melo, Daniel Borkmann,
Alan Maguire, Mark Rutland, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Mon, Dec 18, 2023 at 10:17:10PM +0900, Masami Hiramatsu (Google) wrote:
SNIP
> -static void fprobe_exit_handler(struct rethook_node *rh, void *data,
> - unsigned long ret_ip, struct pt_regs *regs)
> +static int fprobe_entry(unsigned long func, unsigned long ret_ip,
> + struct ftrace_regs *fregs, struct fgraph_ops *gops)
> {
> - struct fprobe *fp = (struct fprobe *)data;
> - struct fprobe_rethook_node *fpr;
> - struct ftrace_regs *fregs = (struct ftrace_regs *)regs;
> - int bit;
> + struct fprobe_hlist_node *node, *first;
> + unsigned long *fgraph_data = NULL;
> + unsigned long header;
> + int reserved_words;
> + struct fprobe *fp;
> + int used, ret;
>
> - if (!fp || fprobe_disabled(fp))
> - return;
> + if (WARN_ON_ONCE(!fregs))
> + return 0;
>
> - fpr = container_of(rh, struct fprobe_rethook_node, node);
> + first = node = find_first_fprobe_node(func);
> + if (unlikely(!first))
> + return 0;
> +
> + reserved_words = 0;
> + hlist_for_each_entry_from_rcu(node, hlist) {
> + if (node->addr != func)
> + break;
> + fp = READ_ONCE(node->fp);
> + if (!fp || !fp->exit_handler)
> + continue;
> + /*
> + * Since fprobe can be enabled until the next loop, we ignore the
> + * fprobe's disabled flag in this loop.
> + */
> + reserved_words +=
> + DIV_ROUND_UP(fp->entry_data_size, sizeof(long)) + 1;
> + }
> + node = first;
> + if (reserved_words) {
> + fgraph_data = fgraph_reserve_data(gops->idx, reserved_words * sizeof(long));
> + if (unlikely(!fgraph_data)) {
> + hlist_for_each_entry_from_rcu(node, hlist) {
> + if (node->addr != func)
> + break;
> + fp = READ_ONCE(node->fp);
> + if (fp && !fprobe_disabled(fp))
> + fp->nmissed++;
> + }
> + return 0;
> + }
> + }
this looks expensive compared to what we do now.. IIUC due to the graph
ops limitations (16 ctive ops), you have just single graph ops for fprobe
and each fprobe registration stores ips into hash which you need to search
in here to get registered callbacks..?
I wonder would it make sense to allow arbitrary number of active graph_ops
with the price some callback might fail because there's no stack space so
each fprobe instance would have its own graph_ops.. and we would get rid
of the code above (and below) ?
jirka
>
> /*
> - * we need to assure no calls to traceable functions in-between the
> - * end of fprobe_handler and the beginning of fprobe_exit_handler.
> + * TODO: recursion detection has been done in the fgraph. Thus we need
> + * to add a callback to increment missed counter.
> */
> - bit = ftrace_test_recursion_trylock(fpr->entry_ip, fpr->entry_parent_ip);
> - if (bit < 0) {
> - fp->nmissed++;
> + used = 0;
> + hlist_for_each_entry_from_rcu(node, hlist) {
> + void *data;
> +
> + if (node->addr != func)
> + break;
> + fp = READ_ONCE(node->fp);
> + if (!fp || fprobe_disabled(fp))
> + continue;
> +
> + if (fp->entry_data_size && fp->exit_handler)
> + data = fgraph_data + used + 1;
> + else
> + data = NULL;
> +
> + if (fprobe_shared_with_kprobes(fp))
> + ret = __fprobe_kprobe_handler(func, ret_ip, fp, fregs, data);
> + else
> + ret = __fprobe_handler(func, ret_ip, fp, fregs, data);
> + /* If entry_handler returns !0, nmissed is not counted but skips exit_handler. */
> + if (!ret && fp->exit_handler) {
> + int size_words = DIV_ROUND_UP(fp->entry_data_size, sizeof(long));
> +
> + header = encode_fprobe_header(fp, size_words);
> + if (likely(header)) {
> + fgraph_data[used] = header;
> + used += size_words + 1;
> + }
> + }
> + }
> + if (used < reserved_words)
> + memset(fgraph_data + used, 0, reserved_words - used);
> +
> + /* If any exit_handler is set, data must be used. */
> + return used != 0;
> +}
> +NOKPROBE_SYMBOL(fprobe_entry);
> +
> +static void fprobe_return(unsigned long func, unsigned long ret_ip,
> + struct ftrace_regs *fregs, struct fgraph_ops *gops)
> +{
> + unsigned long *fgraph_data = NULL;
> + unsigned long val;
> + struct fprobe *fp;
> + int size, curr;
> + int size_words;
> +
> + fgraph_data = (unsigned long *)fgraph_retrieve_data(gops->idx, &size);
> + if (!fgraph_data)
> + return;
> + size_words = DIV_ROUND_UP(size, sizeof(long));
> +
> + preempt_disable();
> +
> + curr = 0;
> + while (size_words > curr) {
> + val = fgraph_data[curr++];
> + if (!val)
> + break;
> +
> + size = decode_fprobe_header(val, &fp);
> + if (fp && is_fprobe_still_exist(fp) && !fprobe_disabled(fp)) {
> + if (WARN_ON_ONCE(curr + size > size_words))
> + break;
> + fp->exit_handler(fp, func, ret_ip, fregs,
> + size ? fgraph_data + curr : NULL);
> + }
> + curr += size + 1;
> + }
> + preempt_enable();
> +}
> +NOKPROBE_SYMBOL(fprobe_return);
> +
> +static struct fgraph_ops fprobe_graph_ops = {
> + .entryregfunc = fprobe_entry,
> + .retregfunc = fprobe_return,
> +};
> +static int fprobe_graph_active;
> +
> +/* Add @addrs to the ftrace filter and register fgraph if needed. */
> +static int fprobe_graph_add_ips(unsigned long *addrs, int num)
> +{
> + int ret;
> +
> + lockdep_assert_held(&fprobe_mutex);
> +
> + ret = ftrace_set_filter_ips(&fprobe_graph_ops.ops, addrs, num, 0, 0);
> + if (ret)
> + return ret;
> +
> + if (!fprobe_graph_active) {
> + ret = register_ftrace_graph(&fprobe_graph_ops);
> + if (WARN_ON_ONCE(ret)) {
> + ftrace_free_filter(&fprobe_graph_ops.ops);
> + return ret;
> + }
> + }
> + fprobe_graph_active++;
> + return 0;
> +}
> +
> +/* Remove @addrs from the ftrace filter and unregister fgraph if possible. */
> +static void fprobe_graph_remove_ips(unsigned long *addrs, int num)
> +{
> + lockdep_assert_held(&fprobe_mutex);
> +
> + fprobe_graph_active--;
> + if (!fprobe_graph_active) {
> + /* Q: should we unregister it ? */
> + unregister_ftrace_graph(&fprobe_graph_ops);
> return;
> }
>
> - fp->exit_handler(fp, fpr->entry_ip, ret_ip, fregs,
> - fp->entry_data_size ? (void *)fpr->data : NULL);
> - ftrace_test_recursion_unlock(bit);
> + ftrace_set_filter_ips(&fprobe_graph_ops.ops, addrs, num, 1, 0);
> }
> -NOKPROBE_SYMBOL(fprobe_exit_handler);
>
> static int symbols_cmp(const void *a, const void *b)
> {
> @@ -176,55 +406,97 @@ static unsigned long *get_ftrace_locations(const char **syms, int num)
> return ERR_PTR(-ENOENT);
> }
>
> -static void fprobe_init(struct fprobe *fp)
> -{
> - fp->nmissed = 0;
> - if (fprobe_shared_with_kprobes(fp))
> - fp->ops.func = fprobe_kprobe_handler;
> - else
> - fp->ops.func = fprobe_handler;
> - fp->ops.flags |= FTRACE_OPS_FL_SAVE_ARGS;
> -}
> +struct filter_match_data {
> + const char *filter;
> + const char *notfilter;
> + size_t index;
> + size_t size;
> + unsigned long *addrs;
> +};
>
> -static int fprobe_init_rethook(struct fprobe *fp, int num)
> +static int filter_match_callback(void *data, const char *name, unsigned long addr)
> {
> - int size;
> + struct filter_match_data *match = data;
>
> - if (num <= 0)
> - return -EINVAL;
> + if (!glob_match(match->filter, name) ||
> + (match->notfilter && glob_match(match->notfilter, name)))
> + return 0;
>
> - if (!fp->exit_handler) {
> - fp->rethook = NULL;
> + if (!ftrace_location(addr))
> return 0;
> - }
>
> - /* Initialize rethook if needed */
> - if (fp->nr_maxactive)
> - size = fp->nr_maxactive;
> - else
> - size = num * num_possible_cpus() * 2;
> - if (size <= 0)
> - return -EINVAL;
> + if (match->addrs)
> + match->addrs[match->index] = addr;
>
> - /* Initialize rethook */
> - fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler,
> - sizeof(struct fprobe_rethook_node), size);
> - if (IS_ERR(fp->rethook))
> - return PTR_ERR(fp->rethook);
> + match->index++;
> + return match->index == match->size;
> +}
>
> - return 0;
> +/*
> + * Make IP list from the filter/no-filter glob patterns.
> + * Return the number of matched symbols, or -ENOENT.
> + */
> +static int ip_list_from_filter(const char *filter, const char *notfilter,
> + unsigned long *addrs, size_t size)
> +{
> + struct filter_match_data match = { .filter = filter, .notfilter = notfilter,
> + .index = 0, .size = size, .addrs = addrs};
> + int ret;
> +
> + ret = kallsyms_on_each_symbol(filter_match_callback, &match);
> + if (ret < 0)
> + return ret;
> + ret = module_kallsyms_on_each_symbol(NULL, filter_match_callback, &match);
> + if (ret < 0)
> + return ret;
> +
> + return match.index ?: -ENOENT;
> }
>
> static void fprobe_fail_cleanup(struct fprobe *fp)
> {
> - if (!IS_ERR_OR_NULL(fp->rethook)) {
> - /* Don't need to cleanup rethook->handler because this is not used. */
> - rethook_free(fp->rethook);
> - fp->rethook = NULL;
> + kfree(fp->hlist_array);
> + fp->hlist_array = NULL;
> +}
> +
> +/* Initialize the fprobe data structure. */
> +static int fprobe_init(struct fprobe *fp, unsigned long *addrs, int num)
> +{
> + struct fprobe_hlist *hlist_array;
> + unsigned long addr;
> + int size, i;
> +
> + if (!fp || !addrs || num <= 0)
> + return -EINVAL;
> +
> + size = ALIGN(fp->entry_data_size, sizeof(long));
> + if (size > MAX_FPROBE_DATA_SIZE)
> + return -E2BIG;
> + fp->entry_data_size = size;
> +
> + hlist_array = kzalloc(struct_size(hlist_array, array, num), GFP_KERNEL);
> + if (!hlist_array)
> + return -ENOMEM;
> +
> + fp->nmissed = 0;
> +
> + hlist_array->size = num;
> + fp->hlist_array = hlist_array;
> + hlist_array->fp = fp;
> + for (i = 0; i < num; i++) {
> + hlist_array->array[i].fp = fp;
> + addr = ftrace_location(addrs[i]);
> + if (!addr) {
> + fprobe_fail_cleanup(fp);
> + return -ENOENT;
> + }
> + hlist_array->array[i].addr = addr;
> }
> - ftrace_free_filter(&fp->ops);
> + return 0;
> }
>
> +#define FPROBE_IPS_MAX INT_MAX
> +
> /**
> * register_fprobe() - Register fprobe to ftrace by pattern.
> * @fp: A fprobe data structure to be registered.
> @@ -238,46 +510,24 @@ static void fprobe_fail_cleanup(struct fprobe *fp)
> */
> int register_fprobe(struct fprobe *fp, const char *filter, const char *notfilter)
> {
> - struct ftrace_hash *hash;
> - unsigned char *str;
> - int ret, len;
> + unsigned long *addrs;
> + int ret;
>
> if (!fp || !filter)
> return -EINVAL;
>
> - fprobe_init(fp);
> -
> - len = strlen(filter);
> - str = kstrdup(filter, GFP_KERNEL);
> - ret = ftrace_set_filter(&fp->ops, str, len, 0);
> - kfree(str);
> - if (ret)
> + ret = ip_list_from_filter(filter, notfilter, NULL, FPROBE_IPS_MAX);
> + if (ret < 0)
> return ret;
>
> - if (notfilter) {
> - len = strlen(notfilter);
> - str = kstrdup(notfilter, GFP_KERNEL);
> - ret = ftrace_set_notrace(&fp->ops, str, len, 0);
> - kfree(str);
> - if (ret)
> - goto out;
> - }
> -
> - /* TODO:
> - * correctly calculate the total number of filtered symbols
> - * from both filter and notfilter.
> - */
> - hash = rcu_access_pointer(fp->ops.local_hash.filter_hash);
> - if (WARN_ON_ONCE(!hash))
> - goto out;
> -
> - ret = fprobe_init_rethook(fp, (int)hash->count);
> - if (!ret)
> - ret = register_ftrace_function(&fp->ops);
> + addrs = kcalloc(ret, sizeof(unsigned long), GFP_KERNEL);
> + if (!addrs)
> + return -ENOMEM;
> + ret = ip_list_from_filter(filter, notfilter, addrs, ret);
> + if (ret > 0)
> + ret = register_fprobe_ips(fp, addrs, ret);
>
> -out:
> - if (ret)
> - fprobe_fail_cleanup(fp);
> + kfree(addrs);
> return ret;
> }
> EXPORT_SYMBOL_GPL(register_fprobe);
> @@ -285,7 +535,7 @@ EXPORT_SYMBOL_GPL(register_fprobe);
> /**
> * register_fprobe_ips() - Register fprobe to ftrace by address.
> * @fp: A fprobe data structure to be registered.
> - * @addrs: An array of target ftrace location addresses.
> + * @addrs: An array of target function address.
> * @num: The number of entries of @addrs.
> *
> * Register @fp to ftrace for enabling the probe on the address given by @addrs.
> @@ -297,23 +547,27 @@ EXPORT_SYMBOL_GPL(register_fprobe);
> */
> int register_fprobe_ips(struct fprobe *fp, unsigned long *addrs, int num)
> {
> - int ret;
> -
> - if (!fp || !addrs || num <= 0)
> - return -EINVAL;
> -
> - fprobe_init(fp);
> + struct fprobe_hlist *hlist_array;
> + int ret, i;
>
> - ret = ftrace_set_filter_ips(&fp->ops, addrs, num, 0, 0);
> + ret = fprobe_init(fp, addrs, num);
> if (ret)
> return ret;
>
> - ret = fprobe_init_rethook(fp, num);
> - if (!ret)
> - ret = register_ftrace_function(&fp->ops);
> + mutex_lock(&fprobe_mutex);
> +
> + hlist_array = fp->hlist_array;
> + ret = fprobe_graph_add_ips(addrs, num);
> + if (!ret) {
> + add_fprobe_hash(fp);
> + for (i = 0; i < hlist_array->size; i++)
> + insert_fprobe_node(&hlist_array->array[i]);
> + }
> + mutex_unlock(&fprobe_mutex);
>
> if (ret)
> fprobe_fail_cleanup(fp);
> +
> return ret;
> }
> EXPORT_SYMBOL_GPL(register_fprobe_ips);
> @@ -351,14 +605,13 @@ EXPORT_SYMBOL_GPL(register_fprobe_syms);
>
> bool fprobe_is_registered(struct fprobe *fp)
> {
> - if (!fp || (fp->ops.saved_func != fprobe_handler &&
> - fp->ops.saved_func != fprobe_kprobe_handler))
> + if (!fp || !fp->hlist_array)
> return false;
> return true;
> }
>
> /**
> - * unregister_fprobe() - Unregister fprobe from ftrace
> + * unregister_fprobe() - Unregister fprobe.
> * @fp: A fprobe data structure to be unregistered.
> *
> * Unregister fprobe (and remove ftrace hooks from the function entries).
> @@ -367,23 +620,40 @@ bool fprobe_is_registered(struct fprobe *fp)
> */
> int unregister_fprobe(struct fprobe *fp)
> {
> - int ret;
> + struct fprobe_hlist *hlist_array;
> + unsigned long *addrs = NULL;
> + int ret = 0, i, count;
>
> - if (!fprobe_is_registered(fp))
> - return -EINVAL;
> + mutex_lock(&fprobe_mutex);
> + if (!fp || !is_fprobe_still_exist(fp)) {
> + ret = -EINVAL;
> + goto out;
> + }
>
> - if (!IS_ERR_OR_NULL(fp->rethook))
> - rethook_stop(fp->rethook);
> + hlist_array = fp->hlist_array;
> + addrs = kcalloc(hlist_array->size, sizeof(unsigned long), GFP_KERNEL);
> + if (!addrs) {
> + ret = -ENOMEM; /* TODO: Fallback to one-by-one loop */
> + goto out;
> + }
>
> - ret = unregister_ftrace_function(&fp->ops);
> - if (ret < 0)
> - return ret;
> + /* Remove non-synonim ips from table and hash */
> + count = 0;
> + for (i = 0; i < hlist_array->size; i++) {
> + if (!delete_fprobe_node(&hlist_array->array[i]))
> + addrs[count++] = hlist_array->array[i].addr;
> + }
> + del_fprobe_hash(fp);
>
> - if (!IS_ERR_OR_NULL(fp->rethook))
> - rethook_free(fp->rethook);
> + fprobe_graph_remove_ips(addrs, count);
>
> - ftrace_free_filter(&fp->ops);
> + kfree_rcu(hlist_array, rcu);
> + fp->hlist_array = NULL;
>
> +out:
> + mutex_unlock(&fprobe_mutex);
> +
> + kfree(addrs);
> return ret;
> }
> EXPORT_SYMBOL_GPL(unregister_fprobe);
> diff --git a/lib/test_fprobe.c b/lib/test_fprobe.c
> index 271ce0caeec0..cf92111b5c79 100644
> --- a/lib/test_fprobe.c
> +++ b/lib/test_fprobe.c
> @@ -17,10 +17,8 @@ static u32 rand1, entry_val, exit_val;
> /* Use indirect calls to avoid inlining the target functions */
> static u32 (*target)(u32 value);
> static u32 (*target2)(u32 value);
> -static u32 (*target_nest)(u32 value, u32 (*nest)(u32));
> static unsigned long target_ip;
> static unsigned long target2_ip;
> -static unsigned long target_nest_ip;
> static int entry_return_value;
>
> static noinline u32 fprobe_selftest_target(u32 value)
> @@ -33,11 +31,6 @@ static noinline u32 fprobe_selftest_target2(u32 value)
> return (value / div_factor) + 1;
> }
>
> -static noinline u32 fprobe_selftest_nest_target(u32 value, u32 (*nest)(u32))
> -{
> - return nest(value + 2);
> -}
> -
> static notrace int fp_entry_handler(struct fprobe *fp, unsigned long ip,
> unsigned long ret_ip,
> struct ftrace_regs *fregs, void *data)
> @@ -79,22 +72,6 @@ static notrace void fp_exit_handler(struct fprobe *fp, unsigned long ip,
> KUNIT_EXPECT_NULL(current_test, data);
> }
>
> -static notrace int nest_entry_handler(struct fprobe *fp, unsigned long ip,
> - unsigned long ret_ip,
> - struct ftrace_regs *fregs, void *data)
> -{
> - KUNIT_EXPECT_FALSE(current_test, preemptible());
> - return 0;
> -}
> -
> -static notrace void nest_exit_handler(struct fprobe *fp, unsigned long ip,
> - unsigned long ret_ip,
> - struct ftrace_regs *fregs, void *data)
> -{
> - KUNIT_EXPECT_FALSE(current_test, preemptible());
> - KUNIT_EXPECT_EQ(current_test, ip, target_nest_ip);
> -}
> -
> /* Test entry only (no rethook) */
> static void test_fprobe_entry(struct kunit *test)
> {
> @@ -191,25 +168,6 @@ static void test_fprobe_data(struct kunit *test)
> KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp));
> }
>
> -/* Test nr_maxactive */
> -static void test_fprobe_nest(struct kunit *test)
> -{
> - static const char *syms[] = {"fprobe_selftest_target", "fprobe_selftest_nest_target"};
> - struct fprobe fp = {
> - .entry_handler = nest_entry_handler,
> - .exit_handler = nest_exit_handler,
> - .nr_maxactive = 1,
> - };
> -
> - current_test = test;
> - KUNIT_EXPECT_EQ(test, 0, register_fprobe_syms(&fp, syms, 2));
> -
> - target_nest(rand1, target);
> - KUNIT_EXPECT_EQ(test, 1, fp.nmissed);
> -
> - KUNIT_EXPECT_EQ(test, 0, unregister_fprobe(&fp));
> -}
> -
> static void test_fprobe_skip(struct kunit *test)
> {
> struct fprobe fp = {
> @@ -247,10 +205,8 @@ static int fprobe_test_init(struct kunit *test)
> rand1 = get_random_u32_above(div_factor);
> target = fprobe_selftest_target;
> target2 = fprobe_selftest_target2;
> - target_nest = fprobe_selftest_nest_target;
> target_ip = get_ftrace_location(target);
> target2_ip = get_ftrace_location(target2);
> - target_nest_ip = get_ftrace_location(target_nest);
>
> return 0;
> }
> @@ -260,7 +216,6 @@ static struct kunit_case fprobe_testcases[] = {
> KUNIT_CASE(test_fprobe),
> KUNIT_CASE(test_fprobe_syms),
> KUNIT_CASE(test_fprobe_data),
> - KUNIT_CASE(test_fprobe_nest),
> KUNIT_CASE(test_fprobe_skip),
> {}
> };
>
^ permalink raw reply [flat|nested] 56+ messages in thread* Re: [PATCH v5 28/34] fprobe: Rewrite fprobe on function-graph tracer
2023-12-19 14:39 ` Jiri Olsa
@ 2023-12-20 1:00 ` Masami Hiramatsu
0 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu @ 2023-12-20 1:00 UTC (permalink / raw)
To: Jiri Olsa
Cc: Alexei Starovoitov, Steven Rostedt, Florent Revest,
linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Arnaldo Carvalho de Melo, Daniel Borkmann,
Alan Maguire, Mark Rutland, Peter Zijlstra, Thomas Gleixner,
Guo Ren
On Tue, 19 Dec 2023 15:39:03 +0100
Jiri Olsa <olsajiri@gmail.com> wrote:
> On Mon, Dec 18, 2023 at 10:17:10PM +0900, Masami Hiramatsu (Google) wrote:
>
> SNIP
>
> > -static void fprobe_exit_handler(struct rethook_node *rh, void *data,
> > - unsigned long ret_ip, struct pt_regs *regs)
> > +static int fprobe_entry(unsigned long func, unsigned long ret_ip,
> > + struct ftrace_regs *fregs, struct fgraph_ops *gops)
> > {
> > - struct fprobe *fp = (struct fprobe *)data;
> > - struct fprobe_rethook_node *fpr;
> > - struct ftrace_regs *fregs = (struct ftrace_regs *)regs;
> > - int bit;
> > + struct fprobe_hlist_node *node, *first;
> > + unsigned long *fgraph_data = NULL;
> > + unsigned long header;
> > + int reserved_words;
> > + struct fprobe *fp;
> > + int used, ret;
> >
> > - if (!fp || fprobe_disabled(fp))
> > - return;
> > + if (WARN_ON_ONCE(!fregs))
> > + return 0;
> >
> > - fpr = container_of(rh, struct fprobe_rethook_node, node);
> > + first = node = find_first_fprobe_node(func);
> > + if (unlikely(!first))
> > + return 0;
> > +
> > + reserved_words = 0;
> > + hlist_for_each_entry_from_rcu(node, hlist) {
> > + if (node->addr != func)
> > + break;
> > + fp = READ_ONCE(node->fp);
> > + if (!fp || !fp->exit_handler)
> > + continue;
> > + /*
> > + * Since fprobe can be enabled until the next loop, we ignore the
> > + * fprobe's disabled flag in this loop.
> > + */
> > + reserved_words +=
> > + DIV_ROUND_UP(fp->entry_data_size, sizeof(long)) + 1;
> > + }
> > + node = first;
> > + if (reserved_words) {
> > + fgraph_data = fgraph_reserve_data(gops->idx, reserved_words * sizeof(long));
> > + if (unlikely(!fgraph_data)) {
> > + hlist_for_each_entry_from_rcu(node, hlist) {
> > + if (node->addr != func)
> > + break;
> > + fp = READ_ONCE(node->fp);
> > + if (fp && !fprobe_disabled(fp))
> > + fp->nmissed++;
> > + }
> > + return 0;
> > + }
> > + }
>
> this looks expensive compared to what we do now.. IIUC due to the graph
> ops limitations (16 ctive ops), you have just single graph ops for fprobe
> and each fprobe registration stores ips into hash which you need to search
> in here to get registered callbacks..?
I think this is not so expensive. Most cases, it only hits 1 fprobe on the
hash. And if the fprobe is only used to hook the entry, reserved_words == 0.
> I wonder would it make sense to allow arbitrary number of active graph_ops
> with the price some callback might fail because there's no stack space so
> each fprobe instance would have its own graph_ops.. and we would get rid
> of the code above (and below) ?
Yeah, actually my first implementation is that. But I realized that doesn't
work, this requires intermediate object which has refcounter because the
"marker" on the shadow stack will be left after unregistering it. We need to
identify which is still available and which is not. And for that purpose,
we may need to introduce similar structure in the fgraph too.
The current multi-fgraph does;
- if CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS=n (called from dedicated mcount
asm code), it has to loop on all fgraph_ops and check the hash, which is
inefficient but it can easily push the return trace entry on the shadow
stack.
- if CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS=y (called from ftrace asm code),
it does not need to loop (that will be done by ftrace) but each handler
does NOT know who pushed the return trace entry on the shadow stack.
Thus it has to decode the shadow stack and check it needs to push return
trace entry or not. And this is hard if the traced function is self-
recursive call or tail call. To check the recursive call, I introduced
a bitmap entry on the shadow stack. This bitmap size limits the max
number of fgraph.
So, unlimit the number of fgraph, we may need to stack the number of fgraph
on the stack and each fgraph callback has to unwind the shadow stack to check
whether their own number is there instead of checking the bit in the bitmap.
That will be more trusted way but maybe slow.
Another option is introducing a pair of pre- and post-callbacks which is called
before and after calling the list/direct call of ftrace_ops. And pre-callback
will push the ret_stack on shadow stack and post-callback will commit or cancel it.
(but this one is hard to design... maybe becomes ugly interface.)
Thank you,
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply [flat|nested] 56+ messages in thread
* [PATCH v5 29/34] tracing/fprobe: Remove nr_maxactive from fprobe
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (27 preceding siblings ...)
2023-12-18 13:17 ` [PATCH v5 28/34] fprobe: Rewrite fprobe on function-graph tracer Masami Hiramatsu (Google)
@ 2023-12-18 13:17 ` Masami Hiramatsu (Google)
2023-12-18 13:17 ` [PATCH v5 30/34] tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS Masami Hiramatsu (Google)
` (4 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:17 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Remove depercated fprobe::nr_maxactive. This involves fprobe events to
rejects the maxactive number.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v2:
- Newly added.
---
include/linux/fprobe.h | 2 --
kernel/trace/trace_fprobe.c | 44 ++++++-------------------------------------
2 files changed, 6 insertions(+), 40 deletions(-)
diff --git a/include/linux/fprobe.h b/include/linux/fprobe.h
index 08b37b0d1d05..c28d06ddfb8e 100644
--- a/include/linux/fprobe.h
+++ b/include/linux/fprobe.h
@@ -47,7 +47,6 @@ struct fprobe_hlist {
* @nmissed: The counter for missing events.
* @flags: The status flag.
* @entry_data_size: The private data storage size.
- * @nr_maxactive: The max number of active functions. (*deprecated)
* @entry_handler: The callback function for function entry.
* @exit_handler: The callback function for function exit.
* @hlist_array: The fprobe_hlist for fprobe search from IP hash table.
@@ -56,7 +55,6 @@ struct fprobe {
unsigned long nmissed;
unsigned int flags;
size_t entry_data_size;
- int nr_maxactive;
int (*entry_handler)(struct fprobe *fp, unsigned long entry_ip,
unsigned long ret_ip, struct ftrace_regs *regs,
diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
index 3982626c82e6..22cf51217b81 100644
--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -375,7 +375,6 @@ static struct trace_fprobe *alloc_trace_fprobe(const char *group,
const char *event,
const char *symbol,
struct tracepoint *tpoint,
- int maxactive,
int nargs, bool is_return)
{
struct trace_fprobe *tf;
@@ -395,7 +394,6 @@ static struct trace_fprobe *alloc_trace_fprobe(const char *group,
tf->fp.entry_handler = fentry_dispatcher;
tf->tpoint = tpoint;
- tf->fp.nr_maxactive = maxactive;
ret = trace_probe_init(&tf->tp, event, group, false);
if (ret < 0)
@@ -974,12 +972,11 @@ static int __trace_fprobe_create(int argc, const char *argv[])
* FETCHARG:TYPE : use TYPE instead of unsigned long.
*/
struct trace_fprobe *tf = NULL;
- int i, len, new_argc = 0, ret = 0;
+ int i, new_argc = 0, ret = 0;
bool is_return = false;
char *symbol = NULL;
const char *event = NULL, *group = FPROBE_EVENT_SYSTEM;
const char **new_argv = NULL;
- int maxactive = 0;
char buf[MAX_EVENT_NAME_LEN];
char gbuf[MAX_EVENT_NAME_LEN];
char sbuf[KSYM_NAME_LEN];
@@ -1000,33 +997,13 @@ static int __trace_fprobe_create(int argc, const char *argv[])
trace_probe_log_init("trace_fprobe", argc, argv);
- event = strchr(&argv[0][1], ':');
- if (event)
- event++;
-
- if (isdigit(argv[0][1])) {
- if (event)
- len = event - &argv[0][1] - 1;
- else
- len = strlen(&argv[0][1]);
- if (len > MAX_EVENT_NAME_LEN - 1) {
- trace_probe_log_err(1, BAD_MAXACT);
- goto parse_error;
- }
- memcpy(buf, &argv[0][1], len);
- buf[len] = '\0';
- ret = kstrtouint(buf, 0, &maxactive);
- if (ret || !maxactive) {
+ if (argv[0][1] != '\0') {
+ if (argv[0][1] != ':') {
+ trace_probe_log_set_index(0);
trace_probe_log_err(1, BAD_MAXACT);
goto parse_error;
}
- /* fprobe rethook instances are iterated over via a list. The
- * maximum should stay reasonable.
- */
- if (maxactive > RETHOOK_MAXACTIVE_MAX) {
- trace_probe_log_err(1, MAXACT_TOO_BIG);
- goto parse_error;
- }
+ event = &argv[0][2];
}
trace_probe_log_set_index(1);
@@ -1036,12 +1013,6 @@ static int __trace_fprobe_create(int argc, const char *argv[])
if (ret < 0)
goto parse_error;
- if (!is_return && maxactive) {
- trace_probe_log_set_index(0);
- trace_probe_log_err(1, BAD_MAXACT_TYPE);
- goto parse_error;
- }
-
trace_probe_log_set_index(0);
if (event) {
ret = traceprobe_parse_event_name(&event, &group, gbuf,
@@ -1095,8 +1066,7 @@ static int __trace_fprobe_create(int argc, const char *argv[])
}
/* setup a probe */
- tf = alloc_trace_fprobe(group, event, symbol, tpoint, maxactive,
- argc, is_return);
+ tf = alloc_trace_fprobe(group, event, symbol, tpoint, argc, is_return);
if (IS_ERR(tf)) {
ret = PTR_ERR(tf);
/* This must return -ENOMEM, else there is a bug */
@@ -1172,8 +1142,6 @@ static int trace_fprobe_show(struct seq_file *m, struct dyn_event *ev)
seq_putc(m, 't');
else
seq_putc(m, 'f');
- if (trace_fprobe_is_return(tf) && tf->fp.nr_maxactive)
- seq_printf(m, "%d", tf->fp.nr_maxactive);
seq_printf(m, ":%s/%s", trace_probe_group_name(&tf->tp),
trace_probe_name(&tf->tp));
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 30/34] tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (28 preceding siblings ...)
2023-12-18 13:17 ` [PATCH v5 29/34] tracing/fprobe: Remove nr_maxactive from fprobe Masami Hiramatsu (Google)
@ 2023-12-18 13:17 ` Masami Hiramatsu (Google)
2023-12-18 13:17 ` [PATCH v5 31/34] bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled Masami Hiramatsu (Google)
` (3 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:17 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Allow fprobe events to be enabled with CONFIG_DYNAMIC_FTRACE_WITH_ARGS.
With this change, fprobe events mostly use ftrace_regs instead of pt_regs.
Note that if the arch doesn't enable HAVE_PT_REGS_COMPAT_FTRACE_REGS,
fprobe events will not be able to be used from perf.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Chagnes in v3:
- Use ftrace_regs_get_return_value().
Changes in v2:
- Define ftrace_regs_get_kernel_stack_nth() for
!CONFIG_HAVE_REGS_AND_STACK_ACCESS_API.
Changes from previous series: Update against the new series.
---
include/linux/ftrace.h | 17 +++++++++
kernel/trace/Kconfig | 1 -
kernel/trace/trace_fprobe.c | 74 ++++++++++++++++++++-------------------
kernel/trace/trace_probe_tmpl.h | 2 +
4 files changed, 55 insertions(+), 39 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 8150edcf8496..ad28daa507f7 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -250,6 +250,23 @@ static __always_inline bool ftrace_regs_has_args(struct ftrace_regs *fregs)
regs_query_register_offset(name)
#endif
+#ifdef CONFIG_HAVE_REGS_AND_STACK_ACCESS_API
+static __always_inline unsigned long
+ftrace_regs_get_kernel_stack_nth(struct ftrace_regs *fregs, unsigned int nth)
+{
+ unsigned long *stackp;
+
+ stackp = (unsigned long *)ftrace_regs_get_stack_pointer(fregs);
+ if (((unsigned long)(stackp + nth) & ~(THREAD_SIZE - 1)) ==
+ ((unsigned long)stackp & ~(THREAD_SIZE - 1)))
+ return *(stackp + nth);
+
+ return 0;
+}
+#else /* !CONFIG_HAVE_REGS_AND_STACK_ACCESS_API */
+#define ftrace_regs_get_kernel_stack_nth(fregs, nth) (0L)
+#endif /* CONFIG_HAVE_REGS_AND_STACK_ACCESS_API */
+
typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip,
struct ftrace_ops *op, struct ftrace_regs *fregs);
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 11a96275b68c..169588021d90 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -681,7 +681,6 @@ config FPROBE_EVENTS
select TRACING
select PROBE_EVENTS
select DYNAMIC_EVENTS
- depends on DYNAMIC_FTRACE_WITH_REGS
default y
help
This allows user to add tracing events on the function entry and
diff --git a/kernel/trace/trace_fprobe.c b/kernel/trace/trace_fprobe.c
index 22cf51217b81..d96de0dbc0cb 100644
--- a/kernel/trace/trace_fprobe.c
+++ b/kernel/trace/trace_fprobe.c
@@ -132,7 +132,7 @@ static int
process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
void *base)
{
- struct pt_regs *regs = rec;
+ struct ftrace_regs *fregs = rec;
unsigned long val;
int ret;
@@ -140,17 +140,17 @@ process_fetch_insn(struct fetch_insn *code, void *rec, void *dest,
/* 1st stage: get value from context */
switch (code->op) {
case FETCH_OP_STACK:
- val = regs_get_kernel_stack_nth(regs, code->param);
+ val = ftrace_regs_get_kernel_stack_nth(fregs, code->param);
break;
case FETCH_OP_STACKP:
- val = kernel_stack_pointer(regs);
+ val = ftrace_regs_get_stack_pointer(fregs);
break;
case FETCH_OP_RETVAL:
- val = regs_return_value(regs);
+ val = ftrace_regs_get_return_value(fregs);
break;
#ifdef CONFIG_HAVE_FUNCTION_ARG_ACCESS_API
case FETCH_OP_ARG:
- val = regs_get_kernel_argument(regs, code->param);
+ val = ftrace_regs_get_argument(fregs, code->param);
break;
#endif
case FETCH_NOP_SYMBOL: /* Ignore a place holder */
@@ -170,7 +170,7 @@ NOKPROBE_SYMBOL(process_fetch_insn)
/* function entry handler */
static nokprobe_inline void
__fentry_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
- struct pt_regs *regs,
+ struct ftrace_regs *fregs,
struct trace_event_file *trace_file)
{
struct fentry_trace_entry_head *entry;
@@ -184,36 +184,36 @@ __fentry_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
if (trace_trigger_soft_disabled(trace_file))
return;
- dsize = __get_data_size(&tf->tp, regs);
+ dsize = __get_data_size(&tf->tp, fregs);
entry = trace_event_buffer_reserve(&fbuffer, trace_file,
sizeof(*entry) + tf->tp.size + dsize);
if (!entry)
return;
- fbuffer.regs = regs;
+ fbuffer.regs = ftrace_get_regs(fregs);
entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
entry->ip = entry_ip;
- store_trace_args(&entry[1], &tf->tp, regs, sizeof(*entry), dsize);
+ store_trace_args(&entry[1], &tf->tp, fregs, sizeof(*entry), dsize);
trace_event_buffer_commit(&fbuffer);
}
static void
fentry_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
- struct pt_regs *regs)
+ struct ftrace_regs *fregs)
{
struct event_file_link *link;
trace_probe_for_each_link_rcu(link, &tf->tp)
- __fentry_trace_func(tf, entry_ip, regs, link->file);
+ __fentry_trace_func(tf, entry_ip, fregs, link->file);
}
NOKPROBE_SYMBOL(fentry_trace_func);
/* Kretprobe handler */
static nokprobe_inline void
__fexit_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
- unsigned long ret_ip, struct pt_regs *regs,
+ unsigned long ret_ip, struct ftrace_regs *fregs,
struct trace_event_file *trace_file)
{
struct fexit_trace_entry_head *entry;
@@ -227,60 +227,63 @@ __fexit_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
if (trace_trigger_soft_disabled(trace_file))
return;
- dsize = __get_data_size(&tf->tp, regs);
+ dsize = __get_data_size(&tf->tp, fregs);
entry = trace_event_buffer_reserve(&fbuffer, trace_file,
sizeof(*entry) + tf->tp.size + dsize);
if (!entry)
return;
- fbuffer.regs = regs;
+ fbuffer.regs = ftrace_get_regs(fregs);
entry = fbuffer.entry = ring_buffer_event_data(fbuffer.event);
entry->func = entry_ip;
entry->ret_ip = ret_ip;
- store_trace_args(&entry[1], &tf->tp, regs, sizeof(*entry), dsize);
+ store_trace_args(&entry[1], &tf->tp, fregs, sizeof(*entry), dsize);
trace_event_buffer_commit(&fbuffer);
}
static void
fexit_trace_func(struct trace_fprobe *tf, unsigned long entry_ip,
- unsigned long ret_ip, struct pt_regs *regs)
+ unsigned long ret_ip, struct ftrace_regs *fregs)
{
struct event_file_link *link;
trace_probe_for_each_link_rcu(link, &tf->tp)
- __fexit_trace_func(tf, entry_ip, ret_ip, regs, link->file);
+ __fexit_trace_func(tf, entry_ip, ret_ip, fregs, link->file);
}
NOKPROBE_SYMBOL(fexit_trace_func);
#ifdef CONFIG_PERF_EVENTS
static int fentry_perf_func(struct trace_fprobe *tf, unsigned long entry_ip,
- struct pt_regs *regs)
+ struct ftrace_regs *fregs)
{
struct trace_event_call *call = trace_probe_event_call(&tf->tp);
struct fentry_trace_entry_head *entry;
struct hlist_head *head;
int size, __size, dsize;
+ struct pt_regs *regs;
int rctx;
head = this_cpu_ptr(call->perf_events);
if (hlist_empty(head))
return 0;
- dsize = __get_data_size(&tf->tp, regs);
+ dsize = __get_data_size(&tf->tp, fregs);
__size = sizeof(*entry) + tf->tp.size + dsize;
size = ALIGN(__size + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
- entry = perf_trace_buf_alloc(size, NULL, &rctx);
+ entry = perf_trace_buf_alloc(size, ®s, &rctx);
if (!entry)
return 0;
+ regs = ftrace_fill_perf_regs(fregs, regs);
+
entry->ip = entry_ip;
memset(&entry[1], 0, dsize);
- store_trace_args(&entry[1], &tf->tp, regs, sizeof(*entry), dsize);
+ store_trace_args(&entry[1], &tf->tp, fregs, sizeof(*entry), dsize);
perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
head, NULL);
return 0;
@@ -289,30 +292,33 @@ NOKPROBE_SYMBOL(fentry_perf_func);
static void
fexit_perf_func(struct trace_fprobe *tf, unsigned long entry_ip,
- unsigned long ret_ip, struct pt_regs *regs)
+ unsigned long ret_ip, struct ftrace_regs *fregs)
{
struct trace_event_call *call = trace_probe_event_call(&tf->tp);
struct fexit_trace_entry_head *entry;
struct hlist_head *head;
int size, __size, dsize;
+ struct pt_regs *regs;
int rctx;
head = this_cpu_ptr(call->perf_events);
if (hlist_empty(head))
return;
- dsize = __get_data_size(&tf->tp, regs);
+ dsize = __get_data_size(&tf->tp, fregs);
__size = sizeof(*entry) + tf->tp.size + dsize;
size = ALIGN(__size + sizeof(u32), sizeof(u64));
size -= sizeof(u32);
- entry = perf_trace_buf_alloc(size, NULL, &rctx);
+ entry = perf_trace_buf_alloc(size, ®s, &rctx);
if (!entry)
return;
+ regs = ftrace_fill_perf_regs(fregs, regs);
+
entry->func = entry_ip;
entry->ret_ip = ret_ip;
- store_trace_args(&entry[1], &tf->tp, regs, sizeof(*entry), dsize);
+ store_trace_args(&entry[1], &tf->tp, fregs, sizeof(*entry), dsize);
perf_trace_buf_submit(entry, size, rctx, call->event.type, 1, regs,
head, NULL);
}
@@ -324,17 +330,14 @@ static int fentry_dispatcher(struct fprobe *fp, unsigned long entry_ip,
void *entry_data)
{
struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp);
- struct pt_regs *regs = ftrace_get_regs(fregs);
int ret = 0;
- if (!regs)
- return 0;
-
if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
- fentry_trace_func(tf, entry_ip, regs);
+ fentry_trace_func(tf, entry_ip, fregs);
+
#ifdef CONFIG_PERF_EVENTS
if (trace_probe_test_flag(&tf->tp, TP_FLAG_PROFILE))
- ret = fentry_perf_func(tf, entry_ip, regs);
+ ret = fentry_perf_func(tf, entry_ip, fregs);
#endif
return ret;
}
@@ -345,16 +348,13 @@ static void fexit_dispatcher(struct fprobe *fp, unsigned long entry_ip,
void *entry_data)
{
struct trace_fprobe *tf = container_of(fp, struct trace_fprobe, fp);
- struct pt_regs *regs = ftrace_get_regs(fregs);
-
- if (!regs)
- return;
if (trace_probe_test_flag(&tf->tp, TP_FLAG_TRACE))
- fexit_trace_func(tf, entry_ip, ret_ip, regs);
+ fexit_trace_func(tf, entry_ip, ret_ip, fregs);
+
#ifdef CONFIG_PERF_EVENTS
if (trace_probe_test_flag(&tf->tp, TP_FLAG_PROFILE))
- fexit_perf_func(tf, entry_ip, ret_ip, regs);
+ fexit_perf_func(tf, entry_ip, ret_ip, fregs);
#endif
}
NOKPROBE_SYMBOL(fexit_dispatcher);
diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h
index 3935b347f874..05445a745a07 100644
--- a/kernel/trace/trace_probe_tmpl.h
+++ b/kernel/trace/trace_probe_tmpl.h
@@ -232,7 +232,7 @@ process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,
/* Sum up total data length for dynamic arrays (strings) */
static nokprobe_inline int
-__get_data_size(struct trace_probe *tp, struct pt_regs *regs)
+__get_data_size(struct trace_probe *tp, void *regs)
{
struct probe_arg *arg;
int i, len, ret = 0;
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 31/34] bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (29 preceding siblings ...)
2023-12-18 13:17 ` [PATCH v5 30/34] tracing/fprobe: Enable fprobe events with CONFIG_DYNAMIC_FTRACE_WITH_ARGS Masami Hiramatsu (Google)
@ 2023-12-18 13:17 ` Masami Hiramatsu (Google)
2023-12-18 13:17 ` [PATCH v5 32/34] selftests: ftrace: Remove obsolate maxactive syntax check Masami Hiramatsu (Google)
` (2 subsequent siblings)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:17 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Enable kprobe_multi feature if CONFIG_FPROBE is enabled. The pt_regs is
converted from ftrace_regs by ftrace_partial_regs(), thus some registers
may always returns 0. But it should be enough for function entry (access
arguments) and exit (access return value).
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Florent Revest <revest@chromium.org>
---
Changes from previous series: NOTHING, Update against the new series.
---
kernel/trace/bpf_trace.c | 22 +++++++++-------------
1 file changed, 9 insertions(+), 13 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index efb792f8f2ea..24ee4e960f1d 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -2503,7 +2503,7 @@ static int __init bpf_event_init(void)
fs_initcall(bpf_event_init);
#endif /* CONFIG_MODULES */
-#if defined(CONFIG_FPROBE) && defined(CONFIG_DYNAMIC_FTRACE_WITH_REGS)
+#ifdef CONFIG_FPROBE
struct bpf_kprobe_multi_link {
struct bpf_link link;
struct fprobe fp;
@@ -2526,6 +2526,8 @@ struct user_syms {
char *buf;
};
+static DEFINE_PER_CPU(struct pt_regs, bpf_kprobe_multi_pt_regs);
+
static int copy_user_syms(struct user_syms *us, unsigned long __user *usyms, u32 cnt)
{
unsigned long __user usymbol;
@@ -2703,13 +2705,14 @@ static u64 bpf_kprobe_multi_entry_ip(struct bpf_run_ctx *ctx)
static int
kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
- unsigned long entry_ip, struct pt_regs *regs)
+ unsigned long entry_ip, struct ftrace_regs *fregs)
{
struct bpf_kprobe_multi_run_ctx run_ctx = {
.link = link,
.entry_ip = entry_ip,
};
struct bpf_run_ctx *old_run_ctx;
+ struct pt_regs *regs;
int err;
if (unlikely(__this_cpu_inc_return(bpf_prog_active) != 1)) {
@@ -2720,6 +2723,7 @@ kprobe_multi_link_prog_run(struct bpf_kprobe_multi_link *link,
migrate_disable();
rcu_read_lock();
+ regs = ftrace_partial_regs(fregs, this_cpu_ptr(&bpf_kprobe_multi_pt_regs));
old_run_ctx = bpf_set_run_ctx(&run_ctx.run_ctx);
err = bpf_prog_run(link->link.prog, regs);
bpf_reset_run_ctx(old_run_ctx);
@@ -2737,13 +2741,9 @@ kprobe_multi_link_handler(struct fprobe *fp, unsigned long fentry_ip,
void *data)
{
struct bpf_kprobe_multi_link *link;
- struct pt_regs *regs = ftrace_get_regs(fregs);
-
- if (!regs)
- return 0;
link = container_of(fp, struct bpf_kprobe_multi_link, fp);
- kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs);
+ kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), fregs);
return 0;
}
@@ -2753,13 +2753,9 @@ kprobe_multi_link_exit_handler(struct fprobe *fp, unsigned long fentry_ip,
void *data)
{
struct bpf_kprobe_multi_link *link;
- struct pt_regs *regs = ftrace_get_regs(fregs);
-
- if (!regs)
- return;
link = container_of(fp, struct bpf_kprobe_multi_link, fp);
- kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), regs);
+ kprobe_multi_link_prog_run(link, get_entry_ip(fentry_ip), fregs);
}
static int symbols_cmp_r(const void *a, const void *b, const void *priv)
@@ -3016,7 +3012,7 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
kvfree(cookies);
return err;
}
-#else /* !CONFIG_FPROBE || !CONFIG_DYNAMIC_FTRACE_WITH_REGS */
+#else /* !CONFIG_FPROBE */
int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
return -EOPNOTSUPP;
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 32/34] selftests: ftrace: Remove obsolate maxactive syntax check
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (30 preceding siblings ...)
2023-12-18 13:17 ` [PATCH v5 31/34] bpf: Enable kprobe_multi feature if CONFIG_FPROBE is enabled Masami Hiramatsu (Google)
@ 2023-12-18 13:17 ` Masami Hiramatsu (Google)
2023-12-18 13:18 ` [PATCH v5 33/34] selftests/ftrace: Add a test case for repeating register/unregister fprobe Masami Hiramatsu (Google)
2023-12-18 13:18 ` [PATCH v5 34/34] Documentation: probes: Update fprobe on function-graph tracer Masami Hiramatsu (Google)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:17 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Since the fprobe event does not support maxactive anymore, stop
testing the maxactive syntax error checking.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
.../ftrace/test.d/dynevent/fprobe_syntax_errors.tc | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc b/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc
index 20e42c030095..66516073ff27 100644
--- a/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc
+++ b/tools/testing/selftests/ftrace/test.d/dynevent/fprobe_syntax_errors.tc
@@ -16,9 +16,7 @@ aarch64)
REG=%r0 ;;
esac
-check_error 'f^100 vfs_read' # MAXACT_NO_KPROBE
-check_error 'f^1a111 vfs_read' # BAD_MAXACT
-check_error 'f^100000 vfs_read' # MAXACT_TOO_BIG
+check_error 'f^100 vfs_read' # BAD_MAXACT
check_error 'f ^non_exist_func' # BAD_PROBE_ADDR (enoent)
check_error 'f ^vfs_read+10' # BAD_PROBE_ADDR
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 33/34] selftests/ftrace: Add a test case for repeating register/unregister fprobe
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (31 preceding siblings ...)
2023-12-18 13:17 ` [PATCH v5 32/34] selftests: ftrace: Remove obsolate maxactive syntax check Masami Hiramatsu (Google)
@ 2023-12-18 13:18 ` Masami Hiramatsu (Google)
2023-12-18 13:18 ` [PATCH v5 34/34] Documentation: probes: Update fprobe on function-graph tracer Masami Hiramatsu (Google)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:18 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
This test case repeats define and undefine the fprobe dynamic event to
ensure that the fprobe does not cause any issue with such operations.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
.../test.d/dynevent/add_remove_fprobe_repeat.tc | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_repeat.tc
diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_repeat.tc b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_repeat.tc
new file mode 100644
index 000000000000..b4ad09237e2a
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_repeat.tc
@@ -0,0 +1,19 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: Generic dynamic event - Repeating add/remove fprobe events
+# requires: dynamic_events "f[:[<group>/][<event>]] <func-name>[%return] [<args>]":README
+
+echo 0 > events/enable
+echo > dynamic_events
+
+PLACE=$FUNCTION_FORK
+REPEAT_TIMES=64
+
+for i in `seq 1 $REPEAT_TIMES`; do
+ echo "f:myevent $PLACE" >> dynamic_events
+ grep -q myevent dynamic_events
+ test -d events/fprobes/myevent
+ echo > dynamic_events
+done
+
+clear_trace
^ permalink raw reply related [flat|nested] 56+ messages in thread* [PATCH v5 34/34] Documentation: probes: Update fprobe on function-graph tracer
2023-12-18 13:11 [PATCH v5 00/34] tracing: fprobe: function_graph: Multi-function graph and fprobe on fgraph Masami Hiramatsu (Google)
` (32 preceding siblings ...)
2023-12-18 13:18 ` [PATCH v5 33/34] selftests/ftrace: Add a test case for repeating register/unregister fprobe Masami Hiramatsu (Google)
@ 2023-12-18 13:18 ` Masami Hiramatsu (Google)
33 siblings, 0 replies; 56+ messages in thread
From: Masami Hiramatsu (Google) @ 2023-12-18 13:18 UTC (permalink / raw)
To: Alexei Starovoitov, Steven Rostedt, Florent Revest
Cc: linux-trace-kernel, LKML, Martin KaFai Lau, bpf, Sven Schnelle,
Alexei Starovoitov, Jiri Olsa, Arnaldo Carvalho de Melo,
Daniel Borkmann, Alan Maguire, Mark Rutland, Peter Zijlstra,
Thomas Gleixner, Guo Ren
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Update fprobe documentation for the new fprobe on function-graph
tracer. This includes some bahvior changes and pt_regs to
ftrace_regs interface change.
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v2:
- Update @fregs parameter explanation.
---
Documentation/trace/fprobe.rst | 42 ++++++++++++++++++++++++++--------------
1 file changed, 27 insertions(+), 15 deletions(-)
diff --git a/Documentation/trace/fprobe.rst b/Documentation/trace/fprobe.rst
index 196f52386aaa..f58bdc64504f 100644
--- a/Documentation/trace/fprobe.rst
+++ b/Documentation/trace/fprobe.rst
@@ -9,9 +9,10 @@ Fprobe - Function entry/exit probe
Introduction
============
-Fprobe is a function entry/exit probe mechanism based on ftrace.
-Instead of using ftrace full feature, if you only want to attach callbacks
-on function entry and exit, similar to the kprobes and kretprobes, you can
+Fprobe is a function entry/exit probe mechanism based on the function-graph
+tracer.
+Instead of tracing all functions, if you want to attach callbacks on specific
+function entry and exit, similar to the kprobes and kretprobes, you can
use fprobe. Compared with kprobes and kretprobes, fprobe gives faster
instrumentation for multiple functions with single handler. This document
describes how to use fprobe.
@@ -91,12 +92,14 @@ The prototype of the entry/exit callback function are as follows:
.. code-block:: c
- int entry_callback(struct fprobe *fp, unsigned long entry_ip, unsigned long ret_ip, struct pt_regs *regs, void *entry_data);
+ int entry_callback(struct fprobe *fp, unsigned long entry_ip, unsigned long ret_ip, struct ftrace_regs *fregs, void *entry_data);
- void exit_callback(struct fprobe *fp, unsigned long entry_ip, unsigned long ret_ip, struct pt_regs *regs, void *entry_data);
+ void exit_callback(struct fprobe *fp, unsigned long entry_ip, unsigned long ret_ip, struct ftrace_regs *fregs, void *entry_data);
-Note that the @entry_ip is saved at function entry and passed to exit handler.
-If the entry callback function returns !0, the corresponding exit callback will be cancelled.
+Note that the @entry_ip is saved at function entry and passed to exit
+handler.
+If the entry callback function returns !0, the corresponding exit callback
+will be cancelled.
@fp
This is the address of `fprobe` data structure related to this handler.
@@ -112,12 +115,10 @@ If the entry callback function returns !0, the corresponding exit callback will
This is the return address that the traced function will return to,
somewhere in the caller. This can be used at both entry and exit.
-@regs
- This is the `pt_regs` data structure at the entry and exit. Note that
- the instruction pointer of @regs may be different from the @entry_ip
- in the entry_handler. If you need traced instruction pointer, you need
- to use @entry_ip. On the other hand, in the exit_handler, the instruction
- pointer of @regs is set to the current return address.
+@fregs
+ This is the `ftrace_regs` data structure at the entry and exit. This
+ includes the function parameters, or the return values. So user can
+ access thos values via appropriate `ftrace_regs_*` APIs.
@entry_data
This is a local storage to share the data between entry and exit handlers.
@@ -125,6 +126,17 @@ If the entry callback function returns !0, the corresponding exit callback will
and `entry_data_size` field when registering the fprobe, the storage is
allocated and passed to both `entry_handler` and `exit_handler`.
+Entry data size and exit handlers on the same function
+======================================================
+
+Since the entry data is passed via per-task stack and it is has limited size,
+the entry data size per probe is limited to `15 * sizeof(long)`. You also need
+to take care that the different fprobes are probing on the same function, this
+limit becomes smaller. The entry data size is aligned to `sizeof(long)` and
+each fprobe which has exit handler uses a `sizeof(long)` space on the stack,
+you should keep the number of fprobes on the same function as small as
+possible.
+
Share the callbacks with kprobes
================================
@@ -165,8 +177,8 @@ This counter counts up when;
- fprobe fails to take ftrace_recursion lock. This usually means that a function
which is traced by other ftrace users is called from the entry_handler.
- - fprobe fails to setup the function exit because of the shortage of rethook
- (the shadow stack for hooking the function return.)
+ - fprobe fails to setup the function exit because of failing to allocate the
+ data buffer from the per-task shadow stack.
The `fprobe::nmissed` field counts up in both cases. Therefore, the former
skips both of entry and exit callback and the latter skips the exit
^ permalink raw reply related [flat|nested] 56+ messages in thread