perf_events: Check for filters on fixed counter events

Intel fixed counters do not support all the filters possible with a
generic counter. Thus, if a fixed counter event is passed but with
certain filters set, then the fixed_mode_idx() function must fail
and the event must be measured in a generic counter instead.

Reject filters are: inv, edge, cnt-mask.

Signed-off-by: Stephane Eranian <eranian@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1254840129-6198-2-git-send-email-eranian@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/include/asm/perf_event.h

@@ -28,9 +28,20 @@
  */
 #define ARCH_PERFMON_EVENT_MASK				    0xffff
 
+/*
+ * filter mask to validate fixed counter events.
+ * the following filters disqualify for fixed counters:
+ *  - inv
+ *  - edge
+ *  - cnt-mask
+ *  The other filters are supported by fixed counters.
+ *  The any-thread option is supported starting with v3.
+ */
+#define ARCH_PERFMON_EVENT_FILTER_MASK			0xff840000
+
 #define ARCH_PERFMON_UNHALTED_CORE_CYCLES_SEL		      0x3c
 #define ARCH_PERFMON_UNHALTED_CORE_CYCLES_UMASK		(0x00 << 8)
-#define ARCH_PERFMON_UNHALTED_CORE_CYCLES_INDEX 		 0
+#define ARCH_PERFMON_UNHALTED_CORE_CYCLES_INDEX			 0
 #define ARCH_PERFMON_UNHALTED_CORE_CYCLES_PRESENT \
 		(1 << (ARCH_PERFMON_UNHALTED_CORE_CYCLES_INDEX))
 

arch/x86/kernel/cpu/perf_event.c

@@ -1349,6 +1349,12 @@ fixed_mode_idx(struct perf_event *event, struct hw_perf_event *hwc)
 	if (!x86_pmu.num_events_fixed)
 		return -1;
 
+	/*
+	 * fixed counters do not take all possible filters
+	 */
+	if (hwc->config & ARCH_PERFMON_EVENT_FILTER_MASK)
+		return -1;
+
 	if (unlikely(hw_event == x86_pmu.event_map(PERF_COUNT_HW_INSTRUCTIONS)))
 		return X86_PMC_IDX_FIXED_INSTRUCTIONS;
 	if (unlikely(hw_event == x86_pmu.event_map(PERF_COUNT_HW_CPU_CYCLES)))