Messages in this thread Patch in this message | | | From | Anshuman Khandual <> | Subject | [PATCH V11 05/10] arm64/perf: Add branch stack support in ARMV8 PMU | Date | Wed, 31 May 2023 09:34:23 +0530 |
| |
This enables support for branch stack sampling event in ARMV8 PMU, checking has_branch_stack() on the event inside 'struct arm_pmu' callbacks. Although these branch stack helpers armv8pmu_branch_XXXXX() are just dummy functions for now. While here, this also defines arm_pmu's sched_task() callback with armv8pmu_sched_task(), which resets the branch record buffer on a sched_in.
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 Tested-by: James Clark <james.clark@arm.com> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> --- arch/arm64/include/asm/perf_event.h | 33 +++++++++++++ drivers/perf/arm_pmuv3.c | 76 ++++++++++++++++++++--------- 2 files changed, 86 insertions(+), 23 deletions(-)
diff --git a/arch/arm64/include/asm/perf_event.h b/arch/arm64/include/asm/perf_event.h index eb7071c9eb34..7548813783ba 100644 --- a/arch/arm64/include/asm/perf_event.h +++ b/arch/arm64/include/asm/perf_event.h @@ -24,4 +24,37 @@ extern unsigned long perf_misc_flags(struct pt_regs *regs); (regs)->pstate = PSR_MODE_EL1h; \ } +struct pmu_hw_events; +struct arm_pmu; +struct perf_event; + +#ifdef CONFIG_PERF_EVENTS +static inline bool has_branch_stack(struct perf_event *event); + +static inline void armv8pmu_branch_read(struct pmu_hw_events *cpuc, struct perf_event *event) +{ + WARN_ON_ONCE(!has_branch_stack(event)); +} + +static inline bool armv8pmu_branch_valid(struct perf_event *event) +{ + WARN_ON_ONCE(!has_branch_stack(event)); + return false; +} + +static inline void armv8pmu_branch_enable(struct perf_event *event) +{ + WARN_ON_ONCE(!has_branch_stack(event)); +} + +static inline void armv8pmu_branch_disable(struct perf_event *event) +{ + WARN_ON_ONCE(!has_branch_stack(event)); +} + +static inline void armv8pmu_branch_probe(struct arm_pmu *arm_pmu) { } +static inline void armv8pmu_branch_reset(void) { } +static inline int armv8pmu_private_alloc(struct arm_pmu *arm_pmu) { return 0; } +static inline void armv8pmu_private_free(struct arm_pmu *arm_pmu) { } +#endif #endif diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c index c98e4039386d..86d803ff1ae3 100644 --- a/drivers/perf/arm_pmuv3.c +++ b/drivers/perf/arm_pmuv3.c @@ -705,38 +705,21 @@ static void armv8pmu_enable_event(struct perf_event *event) * Enable counter and interrupt, and set the counter to count * the event that we're interested in. */ - - /* - * Disable counter - */ armv8pmu_disable_event_counter(event); - - /* - * Set event. - */ armv8pmu_write_event_type(event); - - /* - * Enable interrupt for this counter - */ armv8pmu_enable_event_irq(event); - - /* - * Enable counter - */ armv8pmu_enable_event_counter(event); + + if (has_branch_stack(event)) + armv8pmu_branch_enable(event); } static void armv8pmu_disable_event(struct perf_event *event) { - /* - * Disable counter - */ - armv8pmu_disable_event_counter(event); + if (has_branch_stack(event)) + armv8pmu_branch_disable(event); - /* - * Disable interrupt for this counter - */ + armv8pmu_disable_event_counter(event); armv8pmu_disable_event_irq(event); } @@ -814,6 +797,11 @@ static irqreturn_t armv8pmu_handle_irq(struct arm_pmu *cpu_pmu) if (!armpmu_event_set_period(event)) continue; + if (has_branch_stack(event) && !WARN_ON(!cpuc->branches)) { + armv8pmu_branch_read(cpuc, event); + perf_sample_save_brstack(&data, event, &cpuc->branches->branch_stack); + } + /* * Perf event overflow will queue the processing of the event as * an irq_work which will be taken care of in the handling of @@ -912,6 +900,14 @@ static int armv8pmu_user_event_idx(struct perf_event *event) return event->hw.idx; } +static void armv8pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in) +{ + struct arm_pmu *armpmu = to_arm_pmu(pmu_ctx->pmu); + + if (sched_in && arm_pmu_branch_stack_supported(armpmu)) + armv8pmu_branch_reset(); +} + /* * Add an event filter to a given event. */ @@ -982,6 +978,9 @@ static void armv8pmu_reset(void *info) pmcr |= ARMV8_PMU_PMCR_LP; armv8pmu_pmcr_write(pmcr); + + if (arm_pmu_branch_stack_supported(cpu_pmu)) + armv8pmu_branch_reset(); } static int __armv8_pmuv3_map_event_id(struct arm_pmu *armpmu, @@ -1019,6 +1018,9 @@ static int __armv8_pmuv3_map_event(struct perf_event *event, hw_event_id = __armv8_pmuv3_map_event_id(armpmu, event); + if (has_branch_stack(event) && !armv8pmu_branch_valid(event)) + return -EOPNOTSUPP; + /* * CHAIN events only work when paired with an adjacent counter, and it * never makes sense for a user to open one in isolation, as they'll be @@ -1135,6 +1137,21 @@ static void __armv8pmu_probe_pmu(void *info) cpu_pmu->reg_pmmir = read_pmmir(); else cpu_pmu->reg_pmmir = 0; + armv8pmu_branch_probe(cpu_pmu); +} + +static int branch_records_alloc(struct arm_pmu *armpmu) +{ + struct pmu_hw_events *events; + int cpu; + + for_each_possible_cpu(cpu) { + events = per_cpu_ptr(armpmu->hw_events, cpu); + events->branches = kzalloc(sizeof(struct branch_records), GFP_KERNEL); + if (!events->branches) + return -ENOMEM; + } + return 0; } static int armv8pmu_probe_pmu(struct arm_pmu *cpu_pmu) @@ -1145,12 +1162,24 @@ static int armv8pmu_probe_pmu(struct arm_pmu *cpu_pmu) }; int ret; + ret = armv8pmu_private_alloc(cpu_pmu); + if (ret) + return ret; + ret = smp_call_function_any(&cpu_pmu->supported_cpus, __armv8pmu_probe_pmu, &probe, 1); if (ret) return ret; + if (arm_pmu_branch_stack_supported(cpu_pmu)) { + ret = branch_records_alloc(cpu_pmu); + if (ret) + return ret; + } else { + armv8pmu_private_free(cpu_pmu); + } + return probe.present ? 0 : -ENODEV; } @@ -1214,6 +1243,7 @@ static int armv8_pmu_init(struct arm_pmu *cpu_pmu, char *name, cpu_pmu->set_event_filter = armv8pmu_set_event_filter; cpu_pmu->pmu.event_idx = armv8pmu_user_event_idx; + cpu_pmu->sched_task = armv8pmu_sched_task; cpu_pmu->name = name; cpu_pmu->map_event = map_event; -- 2.25.1
| |