Re: [PATCH 07/12] perf_events: add LBR software filter support forIntel X86
From: Peter Zijlstra
Date: Fri Oct 07 2011 - 07:18:45 EST
On Fri, 2011-10-07 at 12:49 +0200, Stephane Eranian wrote:
> > You could still fuzz it after the cpu passed through and before the
> > kernel reads the LBR. Its a narrow window, but quite feasible.
> Yeah, depending on the depth of the LBR. But then what happens, you
> decode an instruction that is not what was executed.
Right, and Andi's concern is that this might cause our instruction
decoder to blow up, or worse.
The whole false profile thing isn't really a problem, I mean, that's
what you get for poking at your own instruction stream.
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