Re: [BUG] perf: bogus correlation of kernel symbols

From: Ingo Molnar
Date: Thu May 12 2011 - 17:35:58 EST



* Stephane Eranian <eranian@xxxxxxxxxx> wrote:

> The other contradiction, I see, is that you have perf_event paranoia level
> and this new kptr masquerading feature which conflict with each
> other.
>
> You can be allowed to monitor at the kernel level (paranoid=1, default)
> but you cannot correlate symbols:
>
> $ perf record -e cycles:k foo
>
> I suspect if you have this kptr thing turned on, then you need to disallow
> monitoring at the kernel level too.

The better (and consistent) solution would be to turn the kptr_restrict thing
off - see the patch i sent.

Thanks,

Ingo
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