[3.16.y-ckt stable] Patch "perf/x86/intel/uncore: Make sure only uncore events are collected" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    perf/x86/intel/uncore: Make sure only uncore events are collected

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt4.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 2bbcb65eaa6caa8a291b8a02b98cdc96b1a11cba Mon Sep 17 00:00:00 2001
From: Jiri Olsa <jolsa at kernel.org>
Date: Wed, 10 Dec 2014 21:23:50 +0100
Subject: perf/x86/intel/uncore: Make sure only uncore events are collected

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 at deater.net>
Signed-off-by: Jiri Olsa <jolsa at redhat.com>
Cc: Arnaldo Carvalho de Melo <acme at redhat.com>
Cc: Frederic Weisbecker <fweisbec at gmail.com>
Cc: Linus Torvalds <torvalds at linux-foundation.org>
Cc: Peter Zijlstra <peterz at infradead.org>
Cc: Stephane Eranian <eranian at google.com>
Cc: Yan, Zheng <zheng.z.yan at intel.com>
Link: http://lkml.kernel.org/r/1418243031-20367-2-git-send-email-jolsa@kernel.org
Signed-off-by: Ingo Molnar <mingo at kernel.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 arch/x86/kernel/cpu/perf_event_intel_uncore.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore.c b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
index ae6552a0701f..a4c37cb40519 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_uncore.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_uncore.c
@@ -3249,6 +3249,17 @@ static struct intel_uncore_box *uncore_alloc_box(struct intel_uncore_type *type,
 	return box;
 }

+/*
+ * 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)
 {
@@ -3263,13 +3274,18 @@ uncore_collect_events(struct intel_uncore_box *box, struct perf_event *leader, b
 		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)
--
2.1.4