Unverified Commit 50be3428 authored by Alexandre Ghiti's avatar Alexandre Ghiti Committed by Palmer Dabbelt
Browse files

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



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

Signed-off-by: default avatarAlexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: default avatarAndrew Jones <ajones@ventanamicro.com>
Reviewed-by: default avatarAtish Patra <atishp@rivosinc.com>
parent 83c5e13b

drivers/perf/riscv_pmu_legacy.c

+26 −0
Original line number Diff line number Diff line
@@ -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);

}