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    Subject[PATCH V5 2/7] arm64/perf: Update struct arm_pmu for BRBE
    Date
    Although BRBE is an armv8 speciifc HW feature, abstracting out its various
    function callbacks at the struct arm_pmu level is preferred, as it cleaner
    , easier to follow and maintain.

    Besides some helpers i.e brbe_supported(), brbe_probe() and brbe_reset()
    might not fit seamlessly, when tried to be embedded via existing arm_pmu
    helpers in the armv8 implementation.

    Updates the struct arm_pmu to include all required helpers that will drive
    BRBE functionality for a given PMU implementation. These are the following.

    - brbe_filter : Convert perf event filters into BRBE HW filters
    - brbe_probe : Probe BRBE HW and capture its attributes
    - brbe_enable : Enable BRBE HW with a given config
    - brbe_disable : Disable BRBE HW
    - brbe_read : Read BRBE buffer for captured branch records
    - brbe_reset : Reset BRBE buffer
    - brbe_supported: Whether BRBE is supported or not

    A BRBE driver implementation needs to provide these functionalities.

    Cc: Will Deacon <will@kernel.org>
    Cc: Mark Rutland <mark.rutland@arm.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: linux-arm-kernel@lists.infradead.org
    Cc: linux-perf-users@vger.kernel.org
    Cc: linux-kernel@vger.kernel.org
    Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
    ---
    arch/arm64/kernel/perf_event.c | 36 ++++++++++++++++++++++++++++++++++
    include/linux/perf/arm_pmu.h | 21 ++++++++++++++++++++
    2 files changed, 57 insertions(+)

    diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
    index 7b0643fe2f13..c97377e28288 100644
    --- a/arch/arm64/kernel/perf_event.c
    +++ b/arch/arm64/kernel/perf_event.c
    @@ -1025,6 +1025,35 @@ static int armv8pmu_filter_match(struct perf_event *event)
    return evtype != ARMV8_PMUV3_PERFCTR_CHAIN;
    }

    +static void armv8pmu_brbe_filter(struct pmu_hw_events *hw_event, struct perf_event *event)
    +{
    +}
    +
    +static void armv8pmu_brbe_enable(struct pmu_hw_events *hw_event)
    +{
    +}
    +
    +static void armv8pmu_brbe_disable(struct pmu_hw_events *hw_event)
    +{
    +}
    +
    +static void armv8pmu_brbe_read(struct pmu_hw_events *hw_event, struct perf_event *event)
    +{
    +}
    +
    +static void armv8pmu_brbe_probe(struct pmu_hw_events *hw_event)
    +{
    +}
    +
    +static void armv8pmu_brbe_reset(struct pmu_hw_events *hw_event)
    +{
    +}
    +
    +static bool armv8pmu_brbe_supported(struct perf_event *event)
    +{
    + return false;
    +}
    +
    static void armv8pmu_reset(void *info)
    {
    struct arm_pmu *cpu_pmu = (struct arm_pmu *)info;
    @@ -1257,6 +1286,13 @@ static int armv8_pmu_init(struct arm_pmu *cpu_pmu, char *name,

    cpu_pmu->pmu.event_idx = armv8pmu_user_event_idx;

    + cpu_pmu->brbe_filter = armv8pmu_brbe_filter;
    + cpu_pmu->brbe_enable = armv8pmu_brbe_enable;
    + cpu_pmu->brbe_disable = armv8pmu_brbe_disable;
    + cpu_pmu->brbe_read = armv8pmu_brbe_read;
    + cpu_pmu->brbe_probe = armv8pmu_brbe_probe;
    + cpu_pmu->brbe_reset = armv8pmu_brbe_reset;
    + cpu_pmu->brbe_supported = armv8pmu_brbe_supported;
    cpu_pmu->name = name;
    cpu_pmu->map_event = map_event;
    cpu_pmu->attr_groups[ARMPMU_ATTR_GROUP_EVENTS] = events ?
    diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
    index 0356cb6a215d..67a6d59786f2 100644
    --- a/include/linux/perf/arm_pmu.h
    +++ b/include/linux/perf/arm_pmu.h
    @@ -101,6 +101,27 @@ struct arm_pmu {
    void (*reset)(void *);
    int (*map_event)(struct perf_event *event);
    int (*filter_match)(struct perf_event *event);
    +
    + /* Convert perf event filters into BRBE HW filters */
    + void (*brbe_filter)(struct pmu_hw_events *hw_events, struct perf_event *event);
    +
    + /* Probe BRBE HW and capture its attributes */
    + void (*brbe_probe)(struct pmu_hw_events *hw_events);
    +
    + /* Enable BRBE HW with a given config */
    + void (*brbe_enable)(struct pmu_hw_events *hw_events);
    +
    + /* Disable BRBE HW */
    + void (*brbe_disable)(struct pmu_hw_events *hw_events);
    +
    + /* Process BRBE buffer for captured branch records */
    + void (*brbe_read)(struct pmu_hw_events *hw_events, struct perf_event *event);
    +
    + /* Reset BRBE buffer */
    + void (*brbe_reset)(struct pmu_hw_events *hw_events);
    +
    + /* Check whether BRBE is supported */
    + bool (*brbe_supported)(struct perf_event *event);
    int num_events;
    bool secure_access; /* 32-bit ARM only */
    #define ARMV8_PMUV3_MAX_COMMON_EVENTS 0x40
    --
    2.25.1
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