[perfmon2] [PATCH 1/2] perf_events: check for filters on fixed counter events

[Stephane Eranian]

        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 <eran...@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


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