Re: [PATCH 2/2] perf, x86: Don't allow unusual PEBS raw flags

From: Peter Zijlstra
Date: Thu May 02 2013 - 03:39:07 EST


On Wed, Apr 24, 2013 at 04:04:54PM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@xxxxxxxxxxxxxxx>
>
> The PEBS 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.
> """
>
> Since we had problems with this earlier, don't allow cmask, any, edge, invert
> as raw events, except for the ones explicitly listed as pebs_aliases.

If its a simple matter of crap in crap out without affecting anything else we
shouldn't do anything.

The only reason to interfere with the programming is if invalid programming can
affect others like with that MEM_*_RETIRED failure on ivb.
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