Ingo Molnar 0c87197142 perf_counter, x86: Improve interactions with fast-gup ... Improve a few details in perfcounter call-chain recording that makes use of fast-GUP: - Use ACCESS_ONCE() to observe the pte value. ptes are fundamentally racy and can be changed on another CPU, so we have to be careful about how we access them. The PAE branch is already careful with read-barriers - but the non-PAE and 64-bit side needs an ACCESS_ONCE() to make sure the pte value is observed only once. - make the checks a bit stricter so that we can feed it any kind of cra^H^H^H user-space input ;-) Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Ingo Molnar <mingo@elte.hu>		2009-06-19 16:55:16 +02:00
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asm	perf_counter, x86: Improve interactions with fast-gup	2009-06-19 16:55:16 +02:00