Messages in this thread | | | Date | Fri, 28 Feb 2014 16:40:26 +0100 | From | Peter Zijlstra <> | Subject | Re: perf_fuzzer compiled for x32 causes reboot |
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On Fri, Feb 28, 2014 at 07:13:06AM -0800, H. Peter Anvin wrote: > If I'm reading this right we end up going from the page fault > tracepoint to copy_from_user_nmi() without going through NMI, and the > cr2 corruption is obvious. I guess the assumption that only the NMI > path needed to save cr2 is flawed?
It was never assumed it would only go through NMI, but that it would be NMI safe -- and as it turns out, it is that.
What I did assume was that any other callsites would be safe, seeing how they'd already be running in 'normal' contexts.
I had not considered people putting tracepoints _that_ early in the exception paths.
Note that there's more tracepoints there than the one mentioned.
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