Messages in this thread Patch in this message |  | | From | Anshuman Khandual <> | | Subject | [PATCH V8 3/6] arm64/perf: Add branch stack support in struct arm_pmu | | Date | Mon, 23 Jan 2023 18:29:53 +0530 |
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This updates 'struct arm_pmu' for branch stack sampling support later. This adds a new 'features' element in the structure to track supported features, and another 'private' element to encapsulate implementation attributes on a given 'struct arm_pmu'. These updates here will help in tracking any branch stack sampling support, which is being added later. This also adds a helper arm_pmu_branch_stack_supported().
This also enables perf branch stack sampling event on all 'struct arm pmu', supporting the feature but after removing the current gate that blocks such events unconditionally in armpmu_event_init(). Instead a quick probe can be initiated via arm_pmu_branch_stack_supported() to ascertain the support.
Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> --- drivers/perf/arm_pmu.c | 3 +-- include/linux/perf/arm_pmu.h | 12 +++++++++++- 2 files changed, 12 insertions(+), 3 deletions(-)
diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c index 14a3ed3bdb0b..a85b2d67022e 100644 --- a/drivers/perf/arm_pmu.c +++ b/drivers/perf/arm_pmu.c @@ -510,8 +510,7 @@ static int armpmu_event_init(struct perf_event *event) !cpumask_test_cpu(event->cpu, &armpmu->supported_cpus)) return -ENOENT; - /* does not support taken branch sampling */ - if (has_branch_stack(event)) + if (has_branch_stack(event) && !arm_pmu_branch_stack_supported(armpmu)) return -EOPNOTSUPP; return __hw_perf_event_init(event); diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h index 2a9d07cee927..78cb1c895ab9 100644 --- a/include/linux/perf/arm_pmu.h +++ b/include/linux/perf/arm_pmu.h @@ -103,7 +103,9 @@ struct arm_pmu { bool (*filter)(struct pmu *pmu, int cpu); void (*sched_task)(struct perf_event_pmu_context *pmu_ctx, bool sched_in); int num_events; - bool secure_access; /* 32-bit ARM only */ + unsigned int secure_access : 1, /* 32-bit ARM only */ + has_branch_stack: 1, /* 64-bit ARM only */ + reserved : 30; #define ARMV8_PMUV3_MAX_COMMON_EVENTS 0x40 DECLARE_BITMAP(pmceid_bitmap, ARMV8_PMUV3_MAX_COMMON_EVENTS); #define ARMV8_PMUV3_EXT_COMMON_EVENT_BASE 0x4000 @@ -119,8 +121,16 @@ struct arm_pmu { /* Only to be used by ACPI probing code */ unsigned long acpi_cpuid; + + /* Implementation specific attributes */ + void *private; }; +static inline bool arm_pmu_branch_stack_supported(struct arm_pmu *armpmu) +{ + return armpmu->has_branch_stack; +} + #define to_arm_pmu(p) (container_of(p, struct arm_pmu, pmu)) u64 armpmu_event_update(struct perf_event *event); -- 2.25.1
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