Using FIQ (if it is available) gives perf a better insight into the system by allowing code run with interrupts disabled to be profiled.
Signed-off-by: Daniel Thompson daniel.thompson@linaro.org --- arch/arm/include/asm/pmu.h | 4 ++++ arch/arm/kernel/perf_event.c | 2 +- arch/arm/kernel/perf_event_cpu.c | 35 ++++++++++++++++++++++++++++++++--- arch/arm/kernel/traps.c | 3 ++- 4 files changed, 39 insertions(+), 5 deletions(-)
diff --git a/arch/arm/include/asm/pmu.h b/arch/arm/include/asm/pmu.h index b1596bd59129..2a7ea97a4a14 100644 --- a/arch/arm/include/asm/pmu.h +++ b/arch/arm/include/asm/pmu.h @@ -123,6 +123,8 @@ struct arm_pmu {
extern const struct dev_pm_ops armpmu_dev_pm_ops;
+irqreturn_t armpmu_dispatch_irq(int irq, void *dev); + int armpmu_register(struct arm_pmu *armpmu, int type);
u64 armpmu_event_update(struct perf_event *event); @@ -136,6 +138,8 @@ int armpmu_map_event(struct perf_event *event, [PERF_COUNT_HW_CACHE_RESULT_MAX], u32 raw_event_mask);
+void cpu_pmu_handle_fiq(int irq); + struct pmu_probe_info { unsigned int cpuid; unsigned int mask; diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c index f7c65adaa428..5ae9adf7f18e 100644 --- a/arch/arm/kernel/perf_event.c +++ b/arch/arm/kernel/perf_event.c @@ -296,7 +296,7 @@ validate_group(struct perf_event *event) return 0; }
-static irqreturn_t armpmu_dispatch_irq(int irq, void *dev) +irqreturn_t armpmu_dispatch_irq(int irq, void *dev) { struct arm_pmu *armpmu; struct platform_device *plat_device; diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c index a80309087a7b..5c4e9ce23389 100644 --- a/arch/arm/kernel/perf_event_cpu.c +++ b/arch/arm/kernel/perf_event_cpu.c @@ -36,6 +36,9 @@ /* Set at runtime when we know what CPU type we are. */ static struct arm_pmu *cpu_pmu;
+/* Allows us to find out if an IRQ is for us (mostly used from NMI context) */ +static DEFINE_PER_CPU(int, cpu_pmu_irqs); + /* * Despite the names, these two functions are CPU-specific and are used * by the OProfile/perf code. @@ -127,6 +130,24 @@ static void cpu_pmu_free_irq(struct arm_pmu *cpu_pmu) } }
+/* + * This handler is called *unconditionally* from the default NMI/FIQ + * handler. The irq may not be anything to do with us so the main + * job of this function is to figure out if the irq passed in is ours + * or not. + */ +void cpu_pmu_handle_fiq(int irq) +{ + int cpu = smp_processor_id(); + + if (irq != get_cpu_var(cpu_pmu_irqs)) + return; + + (void)armpmu_dispatch_irq(irq, + get_cpu_ptr(&cpu_pmu->hw_events->percpu_pmu)); +} + + static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler) { int i, err, irq, irqs; @@ -170,9 +191,16 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler) continue; }
- err = request_irq(irq, handler, - IRQF_NOBALANCING | IRQF_NO_THREAD, "arm-pmu", - per_cpu_ptr(&hw_events->percpu_pmu, i)); + err = request_nmi_irq( + irq, IRQF_NOBALANCING, "arm-pmu", + per_cpu_ptr(&hw_events->percpu_pmu, i)); + if (err) { + err = request_irq( + irq, handler, + IRQF_NOBALANCING | IRQF_NO_THREAD, + "arm-pmu", + per_cpu_ptr(&hw_events->percpu_pmu, i)); + } if (err) { pr_err("unable to request IRQ%d for ARM PMU counters\n", irq); @@ -180,6 +208,7 @@ static int cpu_pmu_request_irq(struct arm_pmu *cpu_pmu, irq_handler_t handler) }
cpumask_set_cpu(i, &cpu_pmu->active_irqs); + per_cpu(cpu_pmu_irqs, i) = irq; } }
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c index 74c752b9db68..c581e07517ff 100644 --- a/arch/arm/kernel/traps.c +++ b/arch/arm/kernel/traps.c @@ -38,6 +38,7 @@ #include <asm/tls.h> #include <asm/system_misc.h> #include <asm/opcodes.h> +#include <asm/pmu.h>
static const char *handler[]= { @@ -485,7 +486,7 @@ asmlinkage void __exception_irq_entry handle_fiq_as_nmi(struct pt_regs *regs) irq = gic_ack_fiq();
if (irq) { - /* empty - no SPI handlers (yet) */ + cpu_pmu_handle_fiq(irq); } else { #ifdef CONFIG_SMP ipi_cpu_backtrace(regs);