ARM: perf: replace global CPU PMU pointer with per-cpu pointers

A single global CPU PMU pointer is not useful in a system with multiple,
heterogeneous CPU PMUs as we need to access the relevant PMU depending
on the current CPU.

This patch replaces the single global CPU PMU pointer with per-cpu
pointers and changes the OProfile accessors to refer to the PMU affine
to CPU0.

Signed-off-by: Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/arch/arm/kernel/perf_event_cpu.c b/arch/arm/kernel/perf_event_cpu.c
index 1f2740e3dbc028c062c134d58ceb6344f2045d36..280de37056a15dd605327c1ed4b936421b51a492 100644 (file)
--- a/arch/arm/kernel/perf_event_cpu.c
+++ b/arch/arm/kernel/perf_event_cpu.c
@@ -31,7 +31,7 @@
 #include <asm/pmu.h>
 
 /* Set at runtime when we know what CPU type we are. */
-static struct arm_pmu *cpu_pmu;
+static DEFINE_PER_CPU(struct arm_pmu *, cpu_pmu);
 
 static DEFINE_PER_CPU(struct perf_event * [ARMPMU_MAX_HWEVENTS], hw_events);
 static DEFINE_PER_CPU(unsigned long [BITS_TO_LONGS(ARMPMU_MAX_HWEVENTS)], used_mask);
@@ -43,21 +43,22 @@ static DEFINE_PER_CPU(struct pmu_hw_events, cpu_hw_events);
  */
 const char *perf_pmu_name(void)
 {
-       if (!cpu_pmu)
+       struct arm_pmu *pmu = per_cpu(cpu_pmu, 0);
+       if (!pmu)
                return NULL;
 
-       return cpu_pmu->name;
+       return pmu->name;
 }
 EXPORT_SYMBOL_GPL(perf_pmu_name);
 
 int perf_num_counters(void)
 {
-       int max_events = 0;
+       struct arm_pmu *pmu = per_cpu(cpu_pmu, 0);
 
-       if (cpu_pmu != NULL)
-               max_events = cpu_pmu->num_events;
+       if (!pmu)
+               return 0;
 
-       return max_events;
+       return pmu->num_events;
 }
 EXPORT_SYMBOL_GPL(perf_num_counters);
 
@@ -160,11 +161,13 @@ static void cpu_pmu_init(struct arm_pmu *cpu_pmu)
 static int __cpuinit cpu_pmu_notify(struct notifier_block *b,
                                    unsigned long action, void *hcpu)
 {
+       struct arm_pmu *pmu = per_cpu(cpu_pmu, (long)hcpu);
+
        if ((action & ~CPU_TASKS_FROZEN) != CPU_STARTING)
                return NOTIFY_DONE;
 
-       if (cpu_pmu && cpu_pmu->reset)
-               cpu_pmu->reset(cpu_pmu);
+       if (pmu && pmu->reset)
+               pmu->reset(pmu);
        else
                return NOTIFY_DONE;
 
@@ -257,11 +260,7 @@ static int cpu_pmu_device_probe(struct platform_device *pdev)
        struct device_node *node = pdev->dev.of_node;
        struct arm_pmu *pmu;
        int ret = -ENODEV;
-
-       if (cpu_pmu) {
-               pr_info("attempt to register multiple PMU devices!");
-               return -ENOSPC;
-       }
+       int cpu;
 
        pmu = kzalloc(sizeof(struct arm_pmu), GFP_KERNEL);
        if (!pmu) {
@@ -281,10 +280,12 @@ static int cpu_pmu_device_probe(struct platform_device *pdev)
                goto out_free;
        }
 
-       cpu_pmu = pmu;
-       cpu_pmu->plat_device = pdev;
-       cpu_pmu_init(cpu_pmu);
-       ret = armpmu_register(cpu_pmu, PERF_TYPE_RAW);
+       for_each_possible_cpu(cpu)
+               per_cpu(cpu_pmu, cpu) = pmu;
+
+       pmu->plat_device = pdev;
+       cpu_pmu_init(pmu);
+       ret = armpmu_register(pmu, PERF_TYPE_RAW);
 
        if (!ret)
                return 0;