Re: [PATCH V11 04/10] arm64/perf: Add branch stack support in struct pmu_hw_events

From: Mark Rutland
Date: Mon Jun 05 2023 - 04:00:41 EST


On Wed, May 31, 2023 at 09:34:22AM +0530, Anshuman Khandual wrote:
> This adds branch records buffer pointer in 'struct pmu_hw_events' which can
> be used to capture branch records during PMU interrupt. This percpu pointer
> here needs to be allocated first before usage.
>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Tested-by: James Clark <james.clark@xxxxxxx>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>

Acked-by: Mark Rutland <mark.rutland@xxxxxxx>

> ---
> include/linux/perf/arm_pmu.h | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
> index 0da745eaf426..694b241e456c 100644
> --- a/include/linux/perf/arm_pmu.h
> +++ b/include/linux/perf/arm_pmu.h
> @@ -44,6 +44,13 @@ static_assert((PERF_EVENT_FLAG_ARCH & ARMPMU_EVT_47BIT) == ARMPMU_EVT_47BIT);
> }, \
> }
>
> +#define MAX_BRANCH_RECORDS 64
> +
> +struct branch_records {
> + struct perf_branch_stack branch_stack;
> + struct perf_branch_entry branch_entries[MAX_BRANCH_RECORDS];
> +};
> +
> /* The events for a given PMU register set. */
> struct pmu_hw_events {
> /*
> @@ -70,6 +77,8 @@ struct pmu_hw_events {
> struct arm_pmu *percpu_pmu;
>
> int irq;
> +
> + struct branch_records *branches;
> };
>
> enum armpmu_attr_groups {
> --
> 2.25.1
>