Messages in this thread | | | Date | Wed, 23 Oct 2013 08:09:53 +0100 | Subject | Re: [PATCH] perf, x86: Optimize intel_pmu_pebs_fixup_ip() | From | Linus Torvalds <> |
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On Tue, Oct 22, 2013 at 10:12 PM, Peter Zijlstra <peterz@infradead.org> wrote: >> >> Careful! There is one magic piece of state that you need to >> save-and-restore if you do this, namely %cr2. Taking a page fault >> always writes to %cr2, and we must *not* corrupt it in the NMI >> handler. > > It looks like this is already dealt with (a similar thing is done for > i386).
Oh, ok then, we should be good to go. I wonder why we needed that special "_nmi()" version, then..
Please do check that NMI increment the irq-counts etc.. Otherwise you'll need to add the explicit "pagefault_disable/enable()" pair around the __copy_from_user_inatomic()..
Linus
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