linux-kernel - Re: [PATCH 2/6] oprofile/x86: add regs->ip to oprofile trace

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Date:   Tue, 30 Aug 2016 13:30:00 +0200
From:   Robert Richter <rric@...nel.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        "H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Andy Lutomirski <luto@...capital.net>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Brian Gerst <brgerst@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Byungchul Park <byungchul.park@....com>,
        Nilay Vaish <nilayvaish@...il.com>,
        oprofile-list@...ts.sourceforge.net
Subject: Re: [PATCH 2/6] oprofile/x86: add regs->ip to oprofile trace

On 24.08.16 11:50:15, Josh Poimboeuf wrote:
> dump_trace() doesn't add the interrupted instruction's address to the
> trace, so add it manually.  This makes the profile more useful, and also
> makes it more consistent with what perf profiling does.
> 
> Cc: Robert Richter <rric@...nel.org>
> Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
> ---
>  arch/x86/oprofile/backtrace.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c
> index cb31a44..2ef6c8b 100644
> --- a/arch/x86/oprofile/backtrace.c
> +++ b/arch/x86/oprofile/backtrace.c
> @@ -114,9 +114,16 @@ x86_backtrace(struct pt_regs * const regs, unsigned int depth)
>  
>  	if (!user_mode(regs)) {
>  		unsigned long stack = kernel_stack_pointer(regs);
> -		if (depth)
> -			dump_trace(NULL, regs, (unsigned long *)stack, 0,
> -				   &backtrace_ops, &depth);
> +
> +		if (!depth)
> +			return;
> +
> +		oprofile_add_trace(regs->ip);
> +		if (!--depth)
> +			return;
> +
> +		dump_trace(NULL, regs, (unsigned long *)stack, 0,
> +			   &backtrace_ops, &depth);

Acked-by: Robert Richter <rric@...nel.org>

Adding oprofile-list in case someone has objections since this may
break userland tools.

Ingo, please apply the patch to tip once this series is ok to you.

Thanks,

-Robert

>  		return;
>  	}
>  
> -- 
> 2.7.4
>