[PATCH 1/2] perf_events: check for filters on fixed counter events

Stephane Eranian
2009-10-06T14:42:53Z

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>
---
arch/x86/include/asm/perf_event.h | 11 +++++++++++
arch/x86/kernel/cpu/perf_event.c | 6 ++++++
2 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index ad7ce3f..719273b 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -28,6 +28,17 @@
*/
#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
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index b5801c3..1d16bd6 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/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)))
--
1.5.4.3