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ftrace: Hide one more entry in stack trace when ftrace_pid is enabled

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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.

Link: https://lore.kernel.org/linux-trace-kernel/20240528032604.6813-3-tatsuya.s2862@gmail.com

Signed-off-by: Tatsuya S <tatsuya.s2862@gmail.com>
[ Rebased to current tree ]
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Tatsuya S 2024-05-28 12:24:14 +09:00 committed by Steven Rostedt (Google)
parent 4057fd2cdd
commit 6c1f7f0aca
1 changed files with 6 additions and 1 deletions
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7
kernel/trace/trace_functions.c
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@ -231,6 +231,7 @@ 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;
@ -247,7 +248,11 @@ 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);