@@ -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);
@@ -102,7 +102,9 @@ struct arm_pmu {
int (*map_event)(struct perf_event *event);
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
@@ -118,8 +120,16 @@ 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);
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(-)