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From: Ingo Molnar <mingo@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>,
	Andi Kleen <andi@firstfloor.org>,
	LKML <linux-kernel@vger.kernel.org>,
	stable@vger.kernel.org, Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH 2/2] perf, x86: Don't allow unusual PEBS raw flags
Date: Tue, 7 May 2013 13:04:15 +0200	[thread overview]
Message-ID: <20130507110415.GA20999@gmail.com> (raw)
In-Reply-To: <20130507084803.GD9688@dyad.programming.kicks-ass.net>


* Peter Zijlstra <peterz@infradead.org> wrote:

> On Tue, May 07, 2013 at 08:48:05AM +0200, Ingo Molnar wrote:
> > Also, this code only runs when the event is set up, so a bit of sanity 
> > checking can only help, right?
> 
> Nah, its all very circumspect. In fact; while what Andi states is 'true':
> 
> > documentation in the Intel SDM 18.6.1.1 states:
> >
> > """
> > PEBS events are only valid when the following fields of IA32_PERFEVTSELx are all
> > zero: AnyThread, Edge, Invert, CMask.
> > """
> 
> It is also true that Intel themselves gave us events that contradict this; look
> at the intel_pebs_aliases*() functions.
>
> This patch would make it impossible to manually create those events.

I missed that bit of obfuscation ...

> Further, there's something entirely different behind this.

Ok, I agree with you, this needs to be fully explained.

Thanks,

	Ingo

  reply	other threads:[~2013-05-07 11:04 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-24 23:04 [PATCH 1/2] Fix perf LBR filtering Andi Kleen
2013-04-24 23:04 ` [PATCH 2/2] perf, x86: Don't allow unusual PEBS raw flags Andi Kleen
2013-04-29 22:16   ` Stephane Eranian
2013-04-29 22:34     ` Andi Kleen
2013-04-29 23:05       ` Stephane Eranian
2013-05-02  7:37   ` Peter Zijlstra
2013-05-06 17:44     ` Stephane Eranian
2013-05-06 18:52       ` Peter Zijlstra
2013-05-06 22:43         ` Stephane Eranian
2013-05-07  6:48           ` Ingo Molnar
2013-05-07  8:48             ` Peter Zijlstra
2013-05-07 11:04               ` Ingo Molnar [this message]
2013-05-07  8:43           ` Peter Zijlstra
2013-04-24 23:20 ` [PATCH 1/2] Fix perf LBR filtering Ben Hutchings
2013-04-24 23:24 ` Greg KH
2013-04-25 16:25 ` Peter Zijlstra
2013-04-25 16:41   ` Andi Kleen
2013-04-25 16:48     ` Peter Zijlstra
2013-04-25 17:00       ` Andi Kleen
2013-04-25 17:18         ` Peter Zijlstra
2013-04-25 17:42           ` Andi Kleen
2013-04-26  7:56             ` Peter Zijlstra
2013-04-26 19:46               ` Andi Kleen
2013-05-01 11:51                 ` Ingo Molnar
2013-05-01 11:55                   ` Ingo Molnar

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