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

[Ingo Molnar]

* Stephane Eranian <eranian@xxxxxxxxxx> wrote:

> On Thu, May 12, 2011 at 11:35 PM, Ingo Molnar <mingo@xxxxxxx> wrote:
> >
> > * 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.
>
> 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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/