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SubjectRe: [RFC 5/5] x86,perf: Only allow rdpmc if a perf_event is mapped
On Mon, 20 Oct 2014 10:48:13 +0200
Peter Zijlstra <peterz@infradead.org> wrote:

> > - cpumsf_pmu_event_idx is the same as power_pmu_event_idx.
>
> Oh cute, lets ask the s390 people, do you guys have a userspace
> instruction to read the actual counter value?

The "extract cpu counter" ECCTR instruction can be authorized to
be used in user-space with a bit in CR0. With the current code
this bit is not set, the cpu measurement facility is not usable
in user space without a patch to the kernel.

--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.



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