linux-kernel - Re: [PATCH v4 2/6] perf/x86: add support for sampling PEBS machine state registers

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Message-ID: <20140904211631.46b8cad8@as>
Date:	Thu, 4 Sep 2014 21:16:31 -0500
From:	Chuck Ebbert <cebbert.lkml@...il.com>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	linux-kernel@...r.kernel.org, peterz@...radead.org, mingo@...e.hu,
	acme@...hat.com, jolsa@...hat.com, namhyung@...nel.org,
	dsahern@...il.com
Subject: Re: [PATCH v4 2/6] perf/x86: add support for sampling PEBS machine
 state registers

On Wed,  3 Sep 2014 16:59:07 +0200
Stephane Eranian <eranian@...gle.com> wrote:

> PEBS can capture machine state regs at retiremnt of the sampled
> instructions. When precise sampling is enabled on an event, PEBS
> is used, so substitute the interrupted state with the PEBS state.
> Note that not all registers are captured by PEBS. Those missing
> are replaced by the interrupt state counter-parts.
> 
> Signed-off-by: Stephane Eranian <eranian@...gle.com>
> ---
>  arch/x86/kernel/cpu/perf_event_intel_ds.c |   17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c
> b/arch/x86/kernel/cpu/perf_event_intel_ds.c index 9dc4199..139a8a5
> 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
> +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
> @@ -886,6 +886,23 @@ static void __intel_pmu_pebs_event(struct
> perf_event *event, regs.bp = pebs->bp;
>  	regs.sp = pebs->sp;
>  
> +	if (sample_type & PERF_SAMPLE_REGS_INTR) {
> +		regs.ax = pebs->ax;
> +		regs.bx = pebs->bx;
> +		regs.cx = pebs->cx;
> +		regs.si = pebs->si;
> +		regs.di = pebs->di;
> +
> +		regs.r8 = pebs->r8;
> +		regs.r9 = pebs->r9;
> +		regs.r10 = pebs->r10;
> +		regs.r11 = pebs->r11;
> +		regs.r12 = pebs->r12;
> +		regs.r13 = pebs->r13;
> +		regs.r14 = pebs->r14;
> +		regs.r14 = pebs->r15;
   		     ^^^
   		     r15 ???

> +	}
> +
>  	if (event->attr.precise_ip > 1 &&
> x86_pmu.intel_cap.pebs_format >= 2) { regs.ip = pebs->real_ip;
>  		regs.flags |= PERF_EFLAGS_EXACT;

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