Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling taken at 'callq' instruction

From: Peter Zijlstra
Date: Thu Nov 19 2015 - 06:29:05 EST

On Thu, Nov 19, 2015 at 06:43:14PM +0800, Wangnan (F) wrote:
> Also, why not fixing rsp in kernel if that instruction is a 'callq'?
> For avoiding instruction decoding?

Why would the kernel do that? It doesn't need this.

Have userspace do it when trying to interpret the data.

If PERF_EFLAGS_EXACT is set, you know the IP points to the actual
instruction and you can attempt to undo whatever parts of it you need at
post processing time.

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