diff options
| -rw-r--r-- | arch/arm64/include/asm/pmu.h | 2 | ||||
| -rw-r--r-- | arch/arm64/kernel/perf_event.c | 135 |
2 files changed, 136 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/pmu.h b/arch/arm64/include/asm/pmu.h index e6f087806..35d27dbc8 100644 --- a/arch/arm64/include/asm/pmu.h +++ b/arch/arm64/include/asm/pmu.h @@ -64,6 +64,8 @@ struct arm_pmu { u64 max_period; struct platform_device *plat_device; struct pmu_hw_events *(*get_hw_events)(void); + struct notifier_block hotplug_nb; + struct notifier_block cpu_pm_nb; }; #define to_arm_pmu(p) (container_of(p, struct arm_pmu, pmu)) diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index cea1594ff..90d813c29 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -21,6 +21,7 @@ #define pr_fmt(fmt) "hw perfevents: " fmt #include <linux/bitmap.h> +#include <linux/cpu_pm.h> #include <linux/interrupt.h> #include <linux/kernel.h> #include <linux/export.h> @@ -1225,6 +1226,117 @@ cpu_pmu_reset(void) arch_initcall(cpu_pmu_reset); /* + * PMU hardware loses all context when a CPU goes offline. + * When a CPU is hotplugged back in, since some hardware registers are + * UNKNOWN at reset, the PMU must be explicitly reset to avoid reading + * junk values out of them. + */ +static int __cpuinit cpu_pmu_notify(struct notifier_block *b, + unsigned long action, void *hcpu) +{ + int cpu = (unsigned long)hcpu; + struct arm_pmu *pmu = container_of(b, struct arm_pmu, hotplug_nb); + if ((action & ~CPU_TASKS_FROZEN) != CPU_STARTING) + return NOTIFY_DONE; + if (!cpumask_test_cpu(cpu, cpu_online_mask)) + return NOTIFY_DONE; + + if (pmu->reset) + cpu_pmu->reset(pmu); + else + return NOTIFY_DONE; + return NOTIFY_OK; +} + +#ifdef CONFIG_CPU_PM +static void cpu_pm_pmu_setup(struct arm_pmu *armpmu, unsigned long cmd) +{ + struct pmu_hw_events *hw_events = cpu_pmu->get_hw_events(); + struct perf_event *event; + int idx; + + for (idx = 0; idx < armpmu->num_events; idx++) { + /* + * If the counter is not used skip it, there is no + * need of stopping/restarting it. + */ + if (!test_bit(idx, hw_events->used_mask)) + continue; + + event = hw_events->events[idx]; + + switch (cmd) { + case CPU_PM_ENTER: + /* + * Stop and update the counter + */ + armpmu_stop(event, PERF_EF_UPDATE); + break; + case CPU_PM_EXIT: + case CPU_PM_ENTER_FAILED: + /* Restore and enable the counter */ + armpmu_start(event, PERF_EF_RELOAD); + break; + default: + break; + } + } +} + +static int cpu_pm_pmu_notify(struct notifier_block *b, unsigned long cmd, + void *v) +{ + struct arm_pmu *armpmu = container_of(b, struct arm_pmu, cpu_pm_nb); + struct pmu_hw_events *hw_events = cpu_pmu->get_hw_events(); + int enabled = bitmap_weight(hw_events->used_mask, armpmu->num_events); + + if (!cpumask_test_cpu(smp_processor_id(), cpu_online_mask)) + return NOTIFY_DONE; + + /* + * Always reset the PMU registers on power-up even if + * there are no events running. + */ + if (cmd == CPU_PM_EXIT && armpmu->reset) + armpmu->reset(armpmu); + + if (!enabled) + return NOTIFY_OK; + + switch (cmd) { + case CPU_PM_ENTER: + armpmu->stop(); + cpu_pm_pmu_setup(armpmu, cmd); + break; + case CPU_PM_EXIT: + cpu_pm_pmu_setup(armpmu, cmd); + case CPU_PM_ENTER_FAILED: + armpmu->start(); + break; + default: + return NOTIFY_DONE; + } + + return NOTIFY_OK; +} + + +static int cpu_pm_pmu_register(struct arm_pmu *cpu_pmu) +{ + cpu_pmu->cpu_pm_nb.notifier_call = cpu_pm_pmu_notify; + return cpu_pm_register_notifier(&cpu_pmu->cpu_pm_nb); +} + +static void cpu_pm_pmu_unregister(struct arm_pmu *cpu_pmu) +{ + cpu_pm_unregister_notifier(&cpu_pmu->cpu_pm_nb); +} +#else +static inline int cpu_pm_pmu_register(struct arm_pmu *cpu_pmu) { return 0; } +static inline void cpu_pm_pmu_unregister(struct arm_pmu *cpu_pmu) { } +#endif + +/* * PMU platform driver and devicetree bindings. */ static struct of_device_id armpmu_of_device_ids[] = { @@ -1251,7 +1363,27 @@ static struct platform_driver armpmu_driver = { static int __init register_pmu_driver(void) { - return platform_driver_register(&armpmu_driver); + int err; + + cpu_pmu->hotplug_nb.notifier_call = cpu_pmu_notify; + err = register_cpu_notifier(&cpu_pmu->hotplug_nb); + if (err) + return err; + + err = cpu_pm_pmu_register(cpu_pmu); + if (err) + goto err_cpu_pm; + + err = platform_driver_register(&armpmu_driver); + if (err) + goto err_driver; + return 0; + +err_driver: + cpu_pm_pmu_unregister(cpu_pmu); +err_cpu_pm: + unregister_cpu_notifier(&cpu_pmu->hotplug_nb); + return err; } device_initcall(register_pmu_driver); @@ -1260,6 +1392,7 @@ static struct pmu_hw_events *armpmu_get_cpu_events(void) return &__get_cpu_var(cpu_hw_events); } + static void __init cpu_pmu_init(struct arm_pmu *armpmu) { int cpu; |