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

    * 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


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