[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20150716071536.GY19282@twins.programming.kicks-ass.net>
Date: Thu, 16 Jul 2015 09:15:36 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: eranian@...il.com
Cc: Vince Weaver <vincent.weaver@...ne.edu>,
LKML <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
kan.liang@...el.com
Subject: Re: perf: fuzzer triggered warning in intel_pmu_drain_pebs_nhm()
On Thu, Jul 16, 2015 at 08:02:03AM +0200, Stephane Eranian wrote:
> Been running it for a couple of hours, so far so good. I will let it
> run all night.
Thanks!
> > ---
> > arch/x86/kernel/cpu/perf_event_intel_ds.c | 29 +++++++++++++----------------
> > 1 file changed, 13 insertions(+), 16 deletions(-)
> >
> > diff --git a/arch/x86/kernel/cpu/perf_event_intel_ds.c b/arch/x86/kernel/cpu/perf_event_intel_ds.c
> > index 71fc40238843..68d0ced1d229 100644
> > --- a/arch/x86/kernel/cpu/perf_event_intel_ds.c
> > +++ b/arch/x86/kernel/cpu/perf_event_intel_ds.c
> > @@ -1142,6 +1142,7 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
> >
> > for (at = base; at < top; at += x86_pmu.pebs_record_size) {
> > struct pebs_record_nhm *p = at;
> > + u64 pebs_status;
> >
> > /* PEBS v3 has accurate status bits */
> > if (x86_pmu.intel_cap.pebs_format >= 3) {
> > @@ -1152,12 +1153,14 @@ static void intel_pmu_drain_pebs_nhm(struct pt_regs *iregs)
> > continue;
> > }
> >
> > - bit = find_first_bit((unsigned long *)&p->status,
> > + pebs_status = p->status & cpuc->pebs_enabled;
> > + pebs_status &= (1ULL << x86_pmu.max_pebs_events) - 1;
> > +
> > + bit = find_first_bit((unsigned long *)&pebs_status,
> > x86_pmu.max_pebs_events);
> > if (bit >= x86_pmu.max_pebs_events)
> > continue;
Maybe we should WARN in this case? A PEBS entry without any PEBS bits
set in the status field would be 'weird', right?
Maybe something like:
if (WARN(bit >= x86_pmu.max_pebs_events,
"PEBS record without PEBS event! status=%Lx pebs_enabled=%Lx active_mask=%Lx",
p->status, cpuc->pebs_enabled, cpuc->active_mask))
continue;
If that triggers we at least get more info.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists