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drivers: perf: Implement perf event mmap support in the legacy backend

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Implement the needed callbacks in the legacy driver so that we can
directly access the counters through perf in userspace.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
This commit is contained in:
Alexandre Ghiti 2023-08-02 10:03:24 +02:00 committed by Palmer Dabbelt
parent 83c5e13b8c
commit 50be342829
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GPG Key ID: 2E1319F35FBB1889
1 changed files with 26 additions and 0 deletions
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26
drivers/perf/riscv_pmu_legacy.c
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@ -71,6 +71,29 @@ static void pmu_legacy_ctr_start(struct perf_event *event, u64 ival)
local64_set(&hwc->prev_count, initial_val);
}
static uint8_t pmu_legacy_csr_index(struct perf_event *event)
{
return event->hw.idx;
}
static void pmu_legacy_event_mapped(struct perf_event *event, struct mm_struct *mm)
{
if (event->attr.config != PERF_COUNT_HW_CPU_CYCLES &&
event->attr.config != PERF_COUNT_HW_INSTRUCTIONS)
return;
event->hw.flags |= PERF_EVENT_FLAG_USER_READ_CNT;
}
static void pmu_legacy_event_unmapped(struct perf_event *event, struct mm_struct *mm)
{
if (event->attr.config != PERF_COUNT_HW_CPU_CYCLES &&
event->attr.config != PERF_COUNT_HW_INSTRUCTIONS)
return;
event->hw.flags &= ~PERF_EVENT_FLAG_USER_READ_CNT;
}
/*
* This is just a simple implementation to allow legacy implementations
* compatible with new RISC-V PMU driver framework.
@ -91,6 +114,9 @@ static void pmu_legacy_init(struct riscv_pmu *pmu)
pmu->ctr_get_width = NULL;
pmu->ctr_clear_idx = NULL;
pmu->ctr_read = pmu_legacy_read_ctr;
pmu->event_mapped = pmu_legacy_event_mapped;
pmu->event_unmapped = pmu_legacy_event_unmapped;
pmu->csr_index = pmu_legacy_csr_index;
perf_pmu_register(&pmu->pmu, "cpu", PERF_TYPE_RAW);
}