[RFC PATCH 23/32] function_graph: Add a new exit handler with parent_ip and ftrace_regs

Masami Hiramatsu (Google)
2023-11-05T16:11:29Z

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>
---
arch/x86/include/asm/ftrace.h | 2 +
include/linux/ftrace.h | 10 +++++-
kernel/trace/Kconfig | 5 ++-
kernel/trace/fgraph.c | 74 +++++++++++++++++++++++++++--------------
4 files changed, 63 insertions(+), 28 deletions(-)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 897cf02c20b1..74b1d245c38b 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -66,6 +66,8 @@ 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 a6fd930d3500..0c036c5d7c12 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
@@ -131,6 +133,7 @@ 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)
@@ -1041,6 +1044,10 @@ 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);

@@ -1050,6 +1057,7 @@ 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 2623a5987f52..c76fb2f33437 100644
--- a/kernel/trace/fgraph.c
+++ b/kernel/trace/fgraph.c
@@ -624,8 +624,7 @@ int function_graph_enter_regs(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)
+ftrace_pop_return_trace(unsigned long *ret, unsigned long frame_pointer)
{
struct ftrace_ret_stack *ret_stack;
int index;
@@ -670,10 +669,6 @@ ftrace_pop_return_trace(struct ftrace_graph_ret *trace, unsigned long *ret,
#endif

*ret = ret_stack->ret;
- trace->func = ret_stack->func;
- trace->calltime = ret_stack->calltime;
- trace->overrun = atomic_read(&current->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
@@ -712,22 +707,43 @@ 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(&current->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 ret;
+ struct fgraph_ops *gops;
int curr_ret_stack;
+ unsigned long ret;
int stop_at;
int index;
- int idx;

- ret_stack = ftrace_pop_return_trace(&trace, &ret, frame_pointer);
+ ret_stack = ftrace_pop_return_trace(&ret, frame_pointer);

if (unlikely(!ret_stack)) {
ftrace_graph_stop();
@@ -736,11 +752,6 @@ 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
-
curr_ret_stack = current->curr_ret_stack;
index = get_ret_stack_index(current, curr_ret_stack - 1);

@@ -753,8 +764,11 @@ static unsigned long __ftrace_return_to_handler(struct fgraph_ret_regs *ret_regs
val = current->ret_stack[curr_ret_stack - 1];
switch (__get_type(val)) {
case FGRAPH_TYPE_ARRAY:
- idx = __get_array(val);
- fgraph_array[idx]->retfunc(&trace, fgraph_array[idx]);
+ gops = fgraph_array[__get_array(val)];
+ if (gops->retregfunc)
+ gops->retregfunc(ret_stack->func, ret, fregs, gops);
+ else
+ fgraph_call_retfunc(fregs, ret_regs, ret_stack, gops);
curr_ret_stack -= __get_index(val);
break;
case FGRAPH_TYPE_RESERVED:
@@ -778,20 +792,22 @@ 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

@@ -1132,9 +1148,15 @@ 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) {