Re: [PATCH] perf: arm_pmuv3: Fix chained event check for cycle counter
From: Will Deacon
Date: Thu Aug 01 2024 - 07:29:37 EST
On Wed, Jul 10, 2024 at 12:23:56PM -0600, Rob Herring (Arm) wrote:
> Since commit b7e89b0f5bd7 ("perf: arm_pmu: Remove event index to
> counter remapping"), armv8pmu_event_is_chained() is incorrectly
> returning that the cycle counter is chained, but the cycle counter has
> always been 64-bit. The result is trying to configure counter #30 which
> typically doesn't exist.
>
> As ARMV8_PMU_MAX_GENERAL_COUNTERS is the number of counters (31), the
> comparison to the counter index needs to be '<' rather than '<='.
>
> Fixes: b7e89b0f5bd7 ("perf: arm_pmu: Remove event index to counter remapping")
> Signed-off-by: Rob Herring (Arm) <robh@xxxxxxxxxx>
> ---
> drivers/perf/arm_pmuv3.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
> index 3b3a3334cc3f..0e22c68fb804 100644
> --- a/drivers/perf/arm_pmuv3.c
> +++ b/drivers/perf/arm_pmuv3.c
> @@ -482,7 +482,7 @@ static bool armv8pmu_event_is_chained(struct perf_event *event)
> return !armv8pmu_event_has_user_read(event) &&
> armv8pmu_event_is_64bit(event) &&
> !armv8pmu_has_long_event(cpu_pmu) &&
> - (idx <= ARMV8_PMU_MAX_GENERAL_COUNTERS);
> + (idx < ARMV8_PMU_MAX_GENERAL_COUNTERS);
> }
Acked-by: Will Deacon <will@xxxxxxxxxx>
Catalin -- please can you pick this up as a fix?
Cheers,
Will