From: Peter Zijlstra <peterz@infradead.org>
Date: Thu, 10 Sep 2015 09:58:27 +0000 (+0200)
Subject: perf/x86/intel: Fix constraint access
X-Git-Tag: v4.1.11~185
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=37f70c3811230c2ee4a3a9eece54cf7ee5ba00f9;p=platform%2Fkernel%2Flinux-exynos.git

perf/x86/intel: Fix constraint access

commit ebfb4988f0378e2ac3b4a0aa1ea20d724293f392 upstream.

Sasha reported that we can get here with .idx==-1, and
cpuc->event_constraints unallocated.

Suggested-by: Stephane Eranian <eranian@google.com>
Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: b371b5943178 ("perf/x86: Fix event/group validation")
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index 2813ea0..2221261 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -2098,9 +2098,12 @@ static struct event_constraint *
 intel_get_event_constraints(struct cpu_hw_events *cpuc, int idx,
 			    struct perf_event *event)
 {
-	struct event_constraint *c1 = cpuc->event_constraint[idx];
+	struct event_constraint *c1 = NULL;
 	struct event_constraint *c2;
 
+	if (idx >= 0) /* fake does < 0 */
+		c1 = cpuc->event_constraint[idx];
+
 	/*
 	 * first time only
 	 * - static constraint: no change across incremental scheduling calls