ARM: 7356/1: perf: check that we have an event in the PMU IRQ handlers

The PMU IRQ handlers in perf assume that if a counter has overflowed
then perf must be responsible. In the paranoid world of crazy hardware,
this could be false, so check that we do have a valid event before
attempting to dereference NULL in the interrupt path.

Cc: <stable@vger.kernel.org>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 12 insertions, 18 deletions

diff --git a/arch/arm/kernel/perf_event_v6.c b/arch/arm/kernel/perf_event_v6.c
index 88bf15253fbd..b78af0cc6ef3 100644
--- a/arch/arm/kernel/perf_event_v6.c
+++ b/arch/arm/kernel/perf_event_v6.c
@@ -467,23 +467,6 @@ armv6pmu_enable_event(struct hw_perf_event *hwc,
         raw_spin_unlock_irqrestore(&events->pmu_lock, flags);
 }
 
-static int counter_is_active(unsigned long pmcr, int idx)
-{
-        unsigned long mask = 0;
-        if (idx == ARMV6_CYCLE_COUNTER)
-                mask = ARMV6_PMCR_CCOUNT_IEN;
-        else if (idx == ARMV6_COUNTER0)
-                mask = ARMV6_PMCR_COUNT0_IEN;
-        else if (idx == ARMV6_COUNTER1)
-                mask = ARMV6_PMCR_COUNT1_IEN;
-
-        if (mask)
-                return pmcr & mask;
-
-        WARN_ONCE(1, "invalid counter number (%d)\n", idx);
-        return 0;
-}
-
 static irqreturn_t
 armv6pmu_handle_irq(int irq_num,
                     void *dev)
@@ -513,7 +496,8 @@ armv6pmu_handle_irq(int irq_num,
                 struct perf_event *event = cpuc->events[idx];
                 struct hw_perf_event *hwc;
 
-                if (!counter_is_active(pmcr, idx))
+                /* Ignore if we don't have an event. */
+                if (!event)
                         continue;
 
                 /*
diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c
index 050cc8bf7246..4d7095af2ab3 100644
--- a/arch/arm/kernel/perf_event_v7.c
+++ b/arch/arm/kernel/perf_event_v7.c
@@ -960,6 +960,10 @@ static irqreturn_t armv7pmu_handle_irq(int irq_num, void *dev)
                 struct perf_event *event = cpuc->events[idx];
                 struct hw_perf_event *hwc;
 
+                /* Ignore if we don't have an event. */
+                if (!event)
+                        continue;
+
                 /*
                  * We have a single interrupt for all counters. Check that
                  * each counter has overflowed before we process it.
diff --git a/arch/arm/kernel/perf_event_xscale.c b/arch/arm/kernel/perf_event_xscale.c
index 831e019b017c..a5bbd360cc4b 100644
--- a/arch/arm/kernel/perf_event_xscale.c
+++ b/arch/arm/kernel/perf_event_xscale.c
@@ -255,6 +255,9 @@ xscale1pmu_handle_irq(int irq_num, void *dev)
                 struct perf_event *event = cpuc->events[idx];
                 struct hw_perf_event *hwc;
 
+                if (!event)
+                        continue;
+
                 if (!xscale1_pmnc_counter_has_overflowed(pmnc, idx))
                         continue;
 
@@ -592,6 +595,9 @@ xscale2pmu_handle_irq(int irq_num, void *dev)
                 struct perf_event *event = cpuc->events[idx];
                 struct hw_perf_event *hwc;
 
+                if (!event)
+                        continue;
+
                 if (!xscale2_pmnc_counter_has_overflowed(pmnc, idx))
                         continue;