[PATCH v8 21/35] function_graph: Pass ftrace_regs to entryfunc

Masami Hiramatsu (Google)
2024-02-25T15:18:57Z

Pass ftrace_regs to the fgraph_ops::entryfunc(). If ftrace_regs is not
available, it passes a NULL instead. User callback function can access
some registers (including return address) via this ftrace_regs.

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
Changes in v8:
- Just pass ftrace_regs to the handler instead of adding a new
entryregfunc.
- Update riscv ftrace_graph_func().
Changes in v3:
- Update for new multiple fgraph.
---
arch/arm64/kernel/ftrace.c | 2 +
arch/loongarch/kernel/ftrace_dyn.c | 2 +
arch/powerpc/kernel/trace/ftrace.c | 2 +
arch/powerpc/kernel/trace/ftrace_64_pg.c | 10 ++++---
arch/riscv/kernel/ftrace.c | 2 +
arch/x86/kernel/ftrace.c | 42 ++++++++++++++++--------------
include/linux/ftrace.h | 20 +++++++++++---
kernel/trace/fgraph.c | 21 +++++++++------
kernel/trace/ftrace.c | 3 +-
kernel/trace/trace.h | 3 +-
kernel/trace/trace_functions_graph.c | 3 +-
kernel/trace/trace_irqsoff.c | 3 +-
kernel/trace/trace_sched_wakeup.c | 3 +-
kernel/trace/trace_selftest.c | 8 ++++--
14 files changed, 76 insertions(+), 48 deletions(-)

diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index b96740829798..779b975f03f5 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -497,7 +497,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
return;

if (!function_graph_enter_ops(*parent, ip, frame_pointer,
- (void *)frame_pointer, gops))
+ (void *)frame_pointer, 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 920eb673b32b..155bdaba2012 100644
--- a/arch/loongarch/kernel/ftrace_dyn.c
+++ b/arch/loongarch/kernel/ftrace_dyn.c
@@ -254,7 +254,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,

old = *parent;

- if (!function_graph_enter_ops(old, ip, 0, parent, gops))
+ if (!function_graph_enter_ops(old, ip, 0, parent, fregs, gops))
*parent = return_hooker;
}
#else
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index 4ef8bf480279..eeaaa798f4f9 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -423,7 +423,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
if (bit < 0)
goto out;

- if (!function_graph_enter_ops(parent_ip, ip, 0, (unsigned long *)sp, gops))
+ if (!function_graph_enter_ops(parent_ip, ip, 0, (unsigned long *)sp, fregs, gops))
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/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
index eb86fb005f34..59c2824e2aaf 100644
--- a/arch/riscv/kernel/ftrace.c
+++ b/arch/riscv/kernel/ftrace.c
@@ -197,7 +197,7 @@ void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
*/
old = *parent;

- if (!function_graph_enter_ops(old, ip, frame_pointer(regs), parent, gops))
+ if (!function_graph_enter_ops(old, ip, frame_pointer(regs), parent, fregs, gops))
*parent = return_hooker;
}
#else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
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(&current->tracing_graph_pause))
+ return true;
+ return false;
+}

- if (unlikely(atomic_read(&current->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(&current->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 815e865f46c9..d0b1077dcf64 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1061,9 +1061,12 @@ struct fgraph_ops;
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 */
+ struct fgraph_ops *,
+ struct ftrace_regs *); /* entry */

-extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);
+extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace,
+ struct fgraph_ops *gops,
+ struct ftrace_regs *fregs);

#ifdef CONFIG_FUNCTION_GRAPH_TRACER

@@ -1106,13 +1109,20 @@ 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 66d9ce78b292..ea5b0338e254 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -248,7 +248,8 @@ static inline unsigned long make_fgraph_data(int idx, int size, 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, struct fgraph_ops *ops)
+static int entry_run(struct ftrace_graph_ent *trace, struct fgraph_ops *ops,
+ struct ftrace_regs *fregs)
{
return 0;
}
@@ -440,7 +441,7 @@ int __weak ftrace_disable_ftrace_graph_caller(void)
#endif

int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops, struct ftrace_regs *fregs)
{
return 0;
}
@@ -574,8 +575,9 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func,
#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)
+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;
@@ -610,7 +612,7 @@ 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))
+ gops->entryfunc(&trace, gops, fregs))
bitmap |= BIT(i);
else
/* Clear out any saved storage */
@@ -637,6 +639,7 @@ 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;
@@ -661,7 +664,7 @@ 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 (gops->entryfunc(&trace, gops, fregs)) {
if (type == FGRAPH_TYPE_RESERVED)
set_fgraph_index_bitmap(current, index, BIT(gops->idx));
else
@@ -942,7 +945,8 @@ 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;
@@ -1187,7 +1191,8 @@ int register_ftrace_graph(struct fgraph_ops *gops)
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;
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index eeb736582e46..162ece7a39b4 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -816,7 +816,8 @@ void ftrace_graph_graph_time_control(bool enable)
}

static int profile_graph_entry(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops,
+ struct ftrace_regs *fregs)
{
struct ftrace_ret_stack *ret_stack;

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 029a80a38c23..53adc73c460b 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -682,7 +682,8 @@ 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, struct fgraph_ops *gops);
-int trace_graph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops);
+int trace_graph_entry(struct ftrace_graph_ent *trace, struct fgraph_ops *gops,
+ struct ftrace_regs *fregs);

void tracing_start_cmdline_record(void);
void tracing_stop_cmdline_record(void);
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 13d0387ac6a6..b9785fc919c9 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -128,7 +128,8 @@ static inline int ftrace_graph_ignore_irqs(void)
}

int trace_graph_entry(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops,
+ struct ftrace_regs *fregs)
{
unsigned long *task_var = fgraph_get_task_var(gops);
struct trace_array *tr = gops->private;
diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
index fce064e20570..ad739d76fc86 100644
--- a/kernel/trace/trace_irqsoff.c
+++ b/kernel/trace/trace_irqsoff.c
@@ -176,7 +176,8 @@ static int irqsoff_display_graph(struct trace_array *tr, int set)
}

static int irqsoff_graph_entry(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops,
+ struct ftrace_regs *fregs)
{
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 130ca7e7787e..23360a2700de 100644
--- a/kernel/trace/trace_sched_wakeup.c
+++ b/kernel/trace/trace_sched_wakeup.c
@@ -113,7 +113,8 @@ static int wakeup_display_graph(struct trace_array *tr, int set)
}

static int wakeup_graph_entry(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops,
+ struct ftrace_regs *fregs)
{
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 ca1687b274bc..1c3faaeae979 100644
--- a/kernel/trace/trace_selftest.c
+++ b/kernel/trace/trace_selftest.c
@@ -773,7 +773,8 @@ struct fgraph_fixture {
};

static __init int store_entry(struct ftrace_graph_ent *trace,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops,
+ struct ftrace_regs *fregs)
{
struct fgraph_fixture *fixture = container_of(gops, struct fgraph_fixture, gops);
const char *type = fixture->store_type_name;
@@ -1011,7 +1012,8 @@ 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,
- struct fgraph_ops *gops)
+ struct fgraph_ops *gops,
+ struct ftrace_regs *fregs)
{
/* This is harmlessly racy, we want to approximately detect a hang */
if (unlikely(++graph_hang_thresh > GRAPH_MAX_FUNC_TEST)) {
@@ -1025,7 +1027,7 @@ static int trace_graph_entry_watchdog(struct ftrace_graph_ent *trace,
return 0;
}

- return trace_graph_entry(trace, gops);
+ return trace_graph_entry(trace, gops, fregs);
}

static struct fgraph_ops fgraph_ops __initdata = {