| Message ID | 20240527100916.5737-2-tatsuya.s2862@gmail.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] ftrace: Fix stack trace entry generated by ftrace_pid_func() | expand |
On Mon, 27 May 2024 18:44:56 +0900 Tatsuya S <tatsuya.s2862@gmail.com> wrote: > 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. Just a note, this isn't a "fix" but simply an improvement in output. I'm happy to take this (after testing and more reviewing), but it will be for the next merge window, and with a different subject line. "ftrace: Hide one more entry in stack trace when ftrace_pid is enabled" Or something like that. Thanks, -- Steve
On Mon, May 27, 2024 at 07:49:14PM GMT, Steven Rostedt wrote: > On Mon, 27 May 2024 18:44:56 +0900 > Tatsuya S <tatsuya.s2862@gmail.com> wrote: > > > 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. > > Just a note, this isn't a "fix" but simply an improvement in output. > I'm happy to take this (after testing and more reviewing), but it will > be for the next merge window, and with a different subject line. > > "ftrace: Hide one more entry in stack trace when ftrace_pid is enabled" > > Or something like that. > > Thanks, > > -- Steve I will send patch with new subject line. Thank you. Tatsuya
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);
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 <tatsuya.s2862@gmail.com> --- 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/ include/linux/ftrace.h | 2 ++ kernel/trace/ftrace.c | 2 +- kernel/trace/trace_functions.c | 7 ++++++- 3 files changed, 9 insertions(+), 2 deletions(-)