Re: [PATCH] ftrace: Hide a extra entry in stack trace

[ts]

On 9/26/24 2:05 PM, Steven Rostedt wrote:

> On Mon, 23 Sep 2024 12:59:15 +0900
> Tatsuya S <tatsuya.s2862@xxxxxxxxx> wrote:
>
> > A extra entry is shown on stack trace(CONFIG_UNWINDER_ORC=y).
> >
> >      [003] .....   110.171589: vfs_write <-__x64_sys_write
> >      [003] .....   110.171600: <stack trace>
> >   => XXXXXXXXX (Wrong function name)
> >   => vfs_write
> >   => __x64_sys_write
> >   => do_syscall_64
> >   => entry_SYSCALL_64_after_hwframe
> >
> > To resolve this, increment skip in __ftrace_trace_stack().
> > The reason why skip is incremented in __ftrace_trace_stack()
> > is because __ftrace_trace_stack() in stack trace is the only function
> > that wasn't skipped from anywhere.
> >
> > Signed-off-by: Tatsuya S <tatsuya.s2862@xxxxxxxxx>
> > ---
> >   kernel/trace/trace.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> > index c3b2c7dfadef..e0d98621ff23 100644
> > --- a/kernel/trace/trace.c
> > +++ b/kernel/trace/trace.c
> > @@ -2919,6 +2919,8 @@ static void __ftrace_trace_stack(struct trace_buffer *buffer,
> >   #ifndef CONFIG_UNWINDER_ORC
> >   	if (!regs)
> >   		skip++;
> > +#else
> > +	skip++;
> >   #endif
> The above #ifdef block should be removed and replaced with;
>
>
> 	if (IS_ENABLED(CONFIG_UNWINDER_ORC) || !regs)
> 		skip++;
>
> >   
> >   	preempt_disable_notrace();
> -- Steve

 I will submit a new patch to fix it.

Thanks.