diff options
| author | Yicong Yang <yangyicong@hisilicon.com> | 2025-08-20 16:45:33 +0800 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2025-09-18 14:35:54 +0100 |
| commit | f8f89e8cf3d668a40106444276d8c448c114e963 (patch) | |
| tree | 4fcb79b296dcca0cc6ca317d1048e97fb398c85b | |
| parent | 00d7a1af5ab58d89c2f0af27485b2d710c862dfc (diff) | |
perf: arm_pmuv3: Factor out PMCCNTR_EL0 use conditions
PMCCNTR_EL0 is preferred for counting CPU_CYCLES under certain
conditions. Factor out the condition check to a separate function
for further extension. Add documents for better understanding.
No functional changes intended.
Reviewed-by: James Clark <james.clark@linaro.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Will Deacon <will@kernel.org>
| -rw-r--r-- | drivers/perf/arm_pmuv3.c | 29 |
1 files changed, 27 insertions, 2 deletions
diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c index f6d7bab5d555..69c5cc8f5606 100644 --- a/drivers/perf/arm_pmuv3.c +++ b/drivers/perf/arm_pmuv3.c @@ -978,6 +978,32 @@ static int armv8pmu_get_chain_idx(struct pmu_hw_events *cpuc, return -EAGAIN; } +static bool armv8pmu_can_use_pmccntr(struct pmu_hw_events *cpuc, + struct perf_event *event) +{ + struct hw_perf_event *hwc = &event->hw; + unsigned long evtype = hwc->config_base & ARMV8_PMU_EVTYPE_EVENT; + + if (evtype != ARMV8_PMUV3_PERFCTR_CPU_CYCLES) + return false; + + /* + * A CPU_CYCLES event with threshold counting cannot use PMCCNTR_EL0 + * since it lacks threshold support. + */ + if (armv8pmu_event_get_threshold(&event->attr)) + return false; + + /* + * PMCCNTR_EL0 is not affected by BRBE controls like BRBCR_ELx.FZP. + * So don't use it for branch events. + */ + if (has_branch_stack(event)) + return false; + + return true; +} + static int armv8pmu_get_event_idx(struct pmu_hw_events *cpuc, struct perf_event *event) { @@ -986,8 +1012,7 @@ static int armv8pmu_get_event_idx(struct pmu_hw_events *cpuc, unsigned long evtype = hwc->config_base & ARMV8_PMU_EVTYPE_EVENT; /* Always prefer to place a cycle counter into the cycle counter. */ - if ((evtype == ARMV8_PMUV3_PERFCTR_CPU_CYCLES) && - !armv8pmu_event_get_threshold(&event->attr) && !has_branch_stack(event)) { + if (armv8pmu_can_use_pmccntr(cpuc, event)) { if (!test_and_set_bit(ARMV8_PMU_CYCLE_IDX, cpuc->used_mask)) return ARMV8_PMU_CYCLE_IDX; else if (armv8pmu_event_is_64bit(event) && |