Messages in this thread | | | Date | Thu, 12 May 2011 23:50:23 +0200 | From | Ingo Molnar <> | Subject | Re: [BUG] perf: bogus correlation of kernel symbols |
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* Stephane Eranian <eranian@google.com> wrote:
> On Thu, May 12, 2011 at 11:35 PM, Ingo Molnar <mingo@elte.hu> wrote: > > > > * Stephane Eranian <eranian@google.com> 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. > > I saw that. But I think that when someone turns it back on, then you need to > increase the perf_events paranoia level to disallow kernel monitoring to > regular users such that you maintain consistency across the board.
Dunno, i would not couple them necessarily - certain users might still have access to kernel symbols via some other channel - for example the System.map.
Thanks,
Ingo
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