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Re: [PATCH 1/3] perf/x86/intel: output LBR support statement after validation

From Andi Kleen <ak@linux.intel.com>
Newsgroups linux.kernel
Subject Re: [PATCH 1/3] perf/x86/intel: output LBR support statement after validation
Date 2016-06-06 04:00 +0200
Message-ID <rGRZD-67c-7@gated-at.bofh.it> (permalink)
References <rFqRP-8y-5@gated-at.bofh.it> <rFqRP-8y-11@gated-at.bofh.it> <rFDm1-82K-9@gated-at.bofh.it> <rFEBs-wH-27@gated-at.bofh.it>
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> It is not because you force LBR to ring3 only that you do not capture
> kernel addresses in the FROM field.
> Keep in mind that LBR priv level filtering applies to the target of
> the branch and not the source. You might
> still get a kernel address if returning from kernel. Now, in callstack
> mode, I think the return branch is never
> actually recorded in the LBR, it just causes a pop, so theoretically
> this should not happen. I'd like to be
> 100% sure of that, though.

Far branches shouldn't be included in call stack LBR. Don't think
there is any other situation where the ring 0 address could leak either.

-Andi
-- 
ak@linux.intel.com -- Speaking for myself only

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Thread

[PATCH 1/3] perf/x86/intel: output LBR support statement after validation David Carrillo-Cisneros <davidcc@google.com> - 2016-06-02 04:50 +0200
  Re: [PATCH 1/3] perf/x86/intel: output LBR support statement after  validation Peter Zijlstra <peterz@infradead.org> - 2016-06-02 10:30 +0200
  Re: [PATCH 1/3] perf/x86/intel: output LBR support statement after  validation Andi Kleen <ak@linux.intel.com> - 2016-06-02 18:10 +0200
    Re: [PATCH 1/3] perf/x86/intel: output LBR support statement after validation Stephane Eranian <eranian@google.com> - 2016-06-02 19:30 +0200
      Re: [PATCH 1/3] perf/x86/intel: output LBR support statement after  validation Andi Kleen <ak@linux.intel.com> - 2016-06-06 04:00 +0200
        Re: [PATCH 1/3] perf/x86/intel: output LBR support statement after validation Stephane Eranian <eranian@google.com> - 2016-06-08 09:30 +0200
          Re: [PATCH 1/3] perf/x86/intel: output LBR support statement after  validation Andi Kleen <ak@linux.intel.com> - 2016-06-08 11:10 +0200

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