[PATCH v2] ftrace: Fix stack trace entry generated by ftrace_pid_func()
From: Tatsuya S <hidden>
Date: 2024-05-27 10:17:56
Also in:
lkml
Subsystem:
function hooks (ftrace), the rest, tracing · Maintainers:
Steven Rostedt, Masami Hiramatsu, Linus Torvalds
On setting set_ftrace_pid, a extra entry generated by ftrace_pid_func()
is shown on stack trace(CONFIG_UNWINDER_FRAME_POINTER=y).
[004] ..... 68.459382: <stack trace>
=> 0xffffffffa00090af
=> ksys_read
=> __x64_sys_read
=> x64_sys_call
=> do_syscall_64
=> entry_SYSCALL_64_after_hwframe
To resolve this issue, increment skip count
in function_stack_trace_call() if pids are set.
Signed-off-by: Tatsuya S <redacted>
---
Changes in v2:
- Fix build warnings reported by kernel test robot
- Link to v1: https://lore.kernel.org/linux-trace-kernel/20240526112658.46740-1-tatsuya.s2862@gmail.com/ (local)
include/linux/ftrace.h | 2 ++
kernel/trace/ftrace.c | 2 +-
kernel/trace/trace_functions.c | 7 ++++++-
3 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 800995c425e0..0855dfe768eb 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h@@ -913,6 +913,8 @@ static inline bool is_ftrace_trampoline(unsigned long addr) /* totally disable ftrace - can not re-enable after this */ void ftrace_kill(void); +bool ftrace_pids_enabled(struct ftrace_ops *ops); + static inline void tracer_disable(void) { #ifdef CONFIG_FUNCTION_TRACER
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 65208d3b5ed9..e8ddd56d1e55 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c@@ -99,7 +99,7 @@ struct ftrace_ops *function_trace_op __read_mostly = &ftrace_list_end; /* What to set function_trace_op to */ static struct ftrace_ops *set_function_trace_op; -static bool ftrace_pids_enabled(struct ftrace_ops *ops) +bool ftrace_pids_enabled(struct ftrace_ops *ops) { struct trace_array *tr;
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 9f1bfbe105e8..455c9a880199 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c@@ -223,6 +223,7 @@ function_stack_trace_call(unsigned long ip, unsigned long parent_ip, long disabled; int cpu; unsigned int trace_ctx; + int skip = STACK_SKIP; if (unlikely(!tr->function_enabled)) return;
@@ -239,7 +240,11 @@ function_stack_trace_call(unsigned long ip, unsigned long parent_ip, if (likely(disabled == 1)) { trace_ctx = tracing_gen_ctx_flags(flags); trace_function(tr, ip, parent_ip, trace_ctx); - __trace_stack(tr, trace_ctx, STACK_SKIP); +#ifdef CONFIG_UNWINDER_FRAME_POINTER + if (ftrace_pids_enabled(op)) + skip++; +#endif + __trace_stack(tr, trace_ctx, skip); } atomic_dec(&data->disabled);
--
2.45.1