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    Subject[PATCH 4.18 130/135] arm64: perf: Reject stand-alone CHAIN events for PMUv3
    Date
    4.18-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Will Deacon <will.deacon@arm.com>

    commit ca2b497253ad01c80061a1f3ee9eb91b5d54a849 upstream.

    It doesn't make sense for a perf event to be configured as a CHAIN event
    in isolation, so extend the arm_pmu structure with a ->filter_match()
    function to allow the backend PMU implementation to reject CHAIN events
    early.

    Cc: <stable@vger.kernel.org>
    Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
    Signed-off-by: Will Deacon <will.deacon@arm.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/arm64/kernel/perf_event.c | 7 +++++++
    drivers/perf/arm_pmu.c | 8 +++++++-
    include/linux/perf/arm_pmu.h | 1 +
    3 files changed, 15 insertions(+), 1 deletion(-)

    --- a/arch/arm64/kernel/perf_event.c
    +++ b/arch/arm64/kernel/perf_event.c
    @@ -823,6 +823,12 @@ static int armv8pmu_set_event_filter(str
    return 0;
    }

    +static int armv8pmu_filter_match(struct perf_event *event)
    +{
    + unsigned long evtype = event->hw.config_base & ARMV8_PMU_EVTYPE_EVENT;
    + return evtype != ARMV8_PMUV3_PERFCTR_CHAIN;
    +}
    +
    static void armv8pmu_reset(void *info)
    {
    struct arm_pmu *cpu_pmu = (struct arm_pmu *)info;
    @@ -968,6 +974,7 @@ static int armv8_pmu_init(struct arm_pmu
    cpu_pmu->reset = armv8pmu_reset,
    cpu_pmu->max_period = (1LLU << 32) - 1,
    cpu_pmu->set_event_filter = armv8pmu_set_event_filter;
    + cpu_pmu->filter_match = armv8pmu_filter_match;

    return 0;
    }
    --- a/drivers/perf/arm_pmu.c
    +++ b/drivers/perf/arm_pmu.c
    @@ -474,7 +474,13 @@ static int armpmu_filter_match(struct pe
    {
    struct arm_pmu *armpmu = to_arm_pmu(event->pmu);
    unsigned int cpu = smp_processor_id();
    - return cpumask_test_cpu(cpu, &armpmu->supported_cpus);
    + int ret;
    +
    + ret = cpumask_test_cpu(cpu, &armpmu->supported_cpus);
    + if (ret && armpmu->filter_match)
    + return armpmu->filter_match(event);
    +
    + return ret;
    }

    static ssize_t armpmu_cpumask_show(struct device *dev,
    --- a/include/linux/perf/arm_pmu.h
    +++ b/include/linux/perf/arm_pmu.h
    @@ -93,6 +93,7 @@ struct arm_pmu {
    void (*stop)(struct arm_pmu *);
    void (*reset)(void *);
    int (*map_event)(struct perf_event *event);
    + int (*filter_match)(struct perf_event *event);
    int num_events;
    u64 max_period;
    bool secure_access; /* 32-bit ARM only */

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