[PATCH 3.14 70/77] perf/x86/intel/uncore: Make sure only uncore events are collected

Greg Kroah-Hartman
2015-01-14T07:54:39Z

From: Jiri Olsa <jolsa@kernel.org>

commit af91568e762d04931dcbdd6bef4655433d8b9418 upstream.

The uncore_collect_events functions assumes that event group
might contain only uncore events which is wrong, because it
might contain any type of events.

This bug leads to uncore framework touching 'not' uncore events,
which could end up all sorts of bugs.

One was triggered by Vince's perf fuzzer, when the uncore code
touched breakpoint event private event space as if it was uncore
event and caused BUG:

BUG: unable to handle kernel paging request at ffffffff82822068
IP: [<ffffffff81020338>] uncore_assign_events+0x188/0x250
...

The code in uncore_assign_events() function was looking for
event->hw.idx data while the event was initialized as a
breakpoint with different members in event->hw union.

This patch forces uncore_collect_events() to collect only uncore
events.

Reported-by: Vince Weaver <vince@deater.net>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Yan, Zheng <zheng.z.yan@intel.com>
Link: http://lkml.kernel.org/r/1418243031-20367-2-git-send-email-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kernel/cpu/perf_event_intel_uncore.c | 22 +++++++++++++++++++---
1 file changed, 19 insertions(+), 3 deletions(-)

--- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
@@ -2886,6 +2886,17 @@ static struct intel_uncore_box *uncore_e
return uncore_pmu_to_box(uncore_event_to_pmu(event), smp_processor_id());
}

+/*
+ * Using uncore_pmu_event_init pmu event_init callback
+ * as a detection point for uncore events.
+ */
+static int uncore_pmu_event_init(struct perf_event *event);
+
+static bool is_uncore_event(struct perf_event *event)
+{
+ return event->pmu->event_init == uncore_pmu_event_init;
+}
+
static int
uncore_collect_events(struct intel_uncore_box *box, struct perf_event *leader, bool dogrp)
{
@@ -2900,13 +2911,18 @@ uncore_collect_events(struct intel_uncor
return -EINVAL;

n = box->n_events;
- box->event_list[n] = leader;
- n++;
+
+ if (is_uncore_event(leader)) {
+ box->event_list[n] = leader;
+ n++;
+ }
+
if (!dogrp)
return n;

list_for_each_entry(event, &leader->sibling_list, group_entry) {
- if (event->state <= PERF_EVENT_STATE_OFF)
+ if (!is_uncore_event(event) ||
+ event->state <= PERF_EVENT_STATE_OFF)
continue;

if (n >= max_count)