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authorWill Deacon <will.deacon@arm.com>2012-11-05 12:34:47 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2012-11-08 16:06:19 +0000
commitf46f979fdac402c1a3decf420b82397cd93236b5 (patch)
treef846a1f59bc4eaf895c2517c0716925b9497b3d1 /arch/arm64
parent3fd9396af83a1e69eaf9ebb573207431d8f265b6 (diff)
arm64: perf: use architected event for CPU cycle counter
We currently use a fake event encoding (0xFF) to indicate CPU cycles so that we don't waste an event counter and can target the hardware cycle counter instead. The problem with this approach is that the event space defined by the architecture permits an implementation to allocate 0xFF for some other event. This patch uses the architected cycle counter encoding (0x11) so that we avoid potentially clashing with event encodings on future CPU implementations. Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64')
-rw-r--r--arch/arm64/kernel/perf_event.c10
1 files changed, 2 insertions, 8 deletions
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index ecbf2d81ec5c..c76c7241125b 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -613,17 +613,11 @@ enum armv8_pmuv3_perf_types {
ARMV8_PMUV3_PERFCTR_BUS_ACCESS = 0x19,
ARMV8_PMUV3_PERFCTR_MEM_ERROR = 0x1A,
ARMV8_PMUV3_PERFCTR_BUS_CYCLES = 0x1D,
-
- /*
- * This isn't an architected event.
- * We detect this event number and use the cycle counter instead.
- */
- ARMV8_PMUV3_PERFCTR_CPU_CYCLES = 0xFF,
};
/* PMUv3 HW events mapping. */
static const unsigned armv8_pmuv3_perf_map[PERF_COUNT_HW_MAX] = {
- [PERF_COUNT_HW_CPU_CYCLES] = ARMV8_PMUV3_PERFCTR_CPU_CYCLES,
+ [PERF_COUNT_HW_CPU_CYCLES] = ARMV8_PMUV3_PERFCTR_CLOCK_CYCLES,
[PERF_COUNT_HW_INSTRUCTIONS] = ARMV8_PMUV3_PERFCTR_INSTR_EXECUTED,
[PERF_COUNT_HW_CACHE_REFERENCES] = ARMV8_PMUV3_PERFCTR_L1_DCACHE_ACCESS,
[PERF_COUNT_HW_CACHE_MISSES] = ARMV8_PMUV3_PERFCTR_L1_DCACHE_REFILL,
@@ -1106,7 +1100,7 @@ static int armv8pmu_get_event_idx(struct pmu_hw_events *cpuc,
unsigned long evtype = event->config_base & ARMV8_EVTYPE_EVENT;
/* Always place a cycle counter into the cycle counter. */
- if (evtype == ARMV8_PMUV3_PERFCTR_CPU_CYCLES) {
+ if (evtype == ARMV8_PMUV3_PERFCTR_CLOCK_CYCLES) {
if (test_and_set_bit(ARMV8_IDX_CYCLE_COUNTER, cpuc->used_mask))
return -EAGAIN;