This is a note to let you know that I've just added the patch titled
perf/x86/intel: Fix PEBSv3 record drain
to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
perf-x86-intel-fix-pebsv3-record-drain.patch
and it can be found in the queue-4.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 8ef9b8455a2a3049efa9e46e8a6402b972a3eb41 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Wed, 7 Sep 2016 14:42:55 +0200
Subject: perf/x86/intel: Fix PEBSv3 record drain
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
commit 8ef9b8455a2a3049efa9e46e8a6402b972a3eb41 upstream.
Alexander hit the WARN_ON_ONCE(!event) on his Skylake while running
the perf fuzzer.
This means the PEBSv3 record included a status bit for an inactive
event, something that _should_ not happen.
Move the code that filters the status bits against our known PEBS
events up a spot to guarantee we only deal with events we know about.
Further add "continue" statements to the WARN_ON_ONCE()s such that
we'll not die nor generate silly events in case we ever do hit them
again.
Reported-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Tested-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vince Weaver <vince@xxxxxxxxxx>
Fixes: a3d86542de88 ("perf/x86/intel/pebs: Add PEBSv3 decoding")
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/events/intel/ds.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1274,18 +1274,18 @@ static void intel_pmu_drain_pebs_nhm(str
struct pebs_record_nhm *p = at;
u64 pebs_status;
- /* PEBS v3 has accurate status bits */
+ pebs_status = p->status & cpuc->pebs_enabled;
+ pebs_status &= (1ULL << x86_pmu.max_pebs_events) - 1;
+
+ /* PEBS v3 has more accurate status bits */
if (x86_pmu.intel_cap.pebs_format >= 3) {
- for_each_set_bit(bit, (unsigned long *)&p->status,
- MAX_PEBS_EVENTS)
+ for_each_set_bit(bit, (unsigned long *)&pebs_status,
+ x86_pmu.max_pebs_events)
counts[bit]++;
continue;
}
- pebs_status = p->status & cpuc->pebs_enabled;
- pebs_status &= (1ULL << x86_pmu.max_pebs_events) - 1;
-
/*
* On some CPUs the PEBS status can be zero when PEBS is
* racing with clearing of GLOBAL_STATUS.
@@ -1333,8 +1333,11 @@ static void intel_pmu_drain_pebs_nhm(str
continue;
event = cpuc->events[bit];
- WARN_ON_ONCE(!event);
- WARN_ON_ONCE(!event->attr.precise_ip);
+ if (WARN_ON_ONCE(!event))
+ continue;
+
+ if (WARN_ON_ONCE(!event->attr.precise_ip))
+ continue;
/* log dropped samples number */
if (error[bit])
Patches currently in stable-queue which might be from peterz@xxxxxxxxxxxxx are
queue-4.7/perf-x86-intel-pt-fix-an-off-by-one-in-address-filter-configuration.patch
queue-4.7/perf-x86-intel-fix-pebsv3-record-drain.patch
queue-4.7/arm64-spinlocks-implement-smp_mb__before_spinlock-as-smp_mb.patch
queue-4.7/perf-x86-intel-pt-do-validate-the-size-of-a-kernel-address-filter.patch
queue-4.7/sched-core-fix-a-race-between-try_to_wake_up-and-a-woken-up-task.patch
queue-4.7/perf-x86-intel-pt-fix-kernel-address-filter-s-offset-validation.patch
queue-4.7/perf-x86-amd-make-hw_cache_references-and-hw_cache_misses-measure-l2.patch
--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html