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From: Andi Kleen <andi@firstfloor.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <andi@firstfloor.org>,
	linux-kernel@vger.kernel.org,
	Stephane Eranian <eranian@google.com>,
	Ingo Molnar <mingo@kernel.org>,
	Vince Weaver <vincent.weaver@maine.edu>
Subject: Re: BUG uncore_assign_events
Date: Wed, 10 Sep 2014 23:59:08 +0200	[thread overview]
Message-ID: <20140910215908.GL4120@two.firstfloor.org> (raw)
In-Reply-To: <20140910091626.GO16043@twins.programming.kicks-ass.net>

> # addr2line -i -e ivb-ep-build/vmlinux ffffffff81025f18
> 
> arch/x86/include/asm/bitops.h:318
> arch/x86/kernel/cpu/perf_event_intel_uncore.c:3339

i == zero  (ok)
c points to some kernel looking address
hwc->idx is 64

     /* fastpath, try to reuse previous register */
        for (i = 0; i < n; i++) {
                hwc = &box->event_list[i]->hw;
                c = hwc->constraint;

                /* never assigned */
                if (hwc->idx == -1)
                        break;

                /* constraint still honored */
                if (!test_bit(hwc->idx, c->idxmsk))
                        break;

My best bet is something goes wrong in uncore_pmu_to_box or
uncore_event_to_pmu in hte caller, so the box is bogus.

Did the test do CPU hot plug?

BTW i don't think it's a security issue because the uncore driver
is only accesible for root.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.

  reply	other threads:[~2014-09-10 21:59 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-10  9:16 BUG uncore_assign_events Peter Zijlstra
2014-09-10 21:59 ` Andi Kleen [this message]
2014-09-11  5:29   ` Chuck Ebbert
2014-09-11 19:21     ` Andi Kleen
2014-09-11  8:11   ` Peter Zijlstra

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