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

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling taken at 'callq' instruction
Date 2015-11-19 12:30 +0100
Message-ID <qwvzB-by-45@gated-at.bofh.it> (permalink)
References (4 earlier) <qw6KS-Af-7@gated-at.bofh.it> <qwr2V-5I2-5@gated-at.bofh.it> <qwrcB-5Lq-5@gated-at.bofh.it> <qwuDv-820-5@gated-at.bofh.it> <qwuWR-88v-15@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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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[BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction "Wangnan (F)" <wangnan0@huawei.com> - 2015-11-18 08:30 +0100
  Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction "Wangnan (F)" <wangnan0@huawei.com> - 2015-11-18 09:20 +0100
    Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction Ingo Molnar <mingo@kernel.org> - 2015-11-18 09:30 +0100
      Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction "Wangnan (F)" <wangnan0@huawei.com> - 2015-11-18 10:00 +0100
        Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction Ingo Molnar <mingo@kernel.org> - 2015-11-19 07:40 +0100
          Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction "Wangnan (F)" <wangnan0@huawei.com> - 2015-11-19 07:50 +0100
            Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction Ingo Molnar <mingo@kernel.org> - 2015-11-19 11:30 +0100
              Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction "Wangnan (F)" <wangnan0@huawei.com> - 2015-11-19 11:50 +0100
                Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction Peter Zijlstra <peterz@infradead.org> - 2015-11-19 12:30 +0100
              Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction Peter Zijlstra <peterz@infradead.org> - 2015-11-19 12:30 +0100
                Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction Ingo Molnar <mingo@kernel.org> - 2015-11-27 09:40 +0100
                Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction Peter Zijlstra <peterz@infradead.org> - 2015-11-30 10:30 +0100
      Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction "Wangnan (F)" <wangnan0@huawei.com> - 2015-11-18 10:10 +0100
  Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction Jiri Olsa <jolsa@redhat.com> - 2015-11-18 09:50 +0100
    Re: [BUG REPORT] perf tools: x86_64: Broken calllchain when sampling  taken at 'callq' instruction "Wangnan (F)" <wangnan0@huawei.com> - 2015-11-18 10:20 +0100

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