ARM64: perf: add support for accessing counters from userspace with mmap way

This patch adds support for accessing perf hw counters
from userspace with usage of perf_event_mmap_page.

Signed-off-by: Yogesh Tillu <yogesh.tillu@linaro.org>
Signed-off-by: Gary S. Robertson <gary.robertson@linaro.org>

2 files changed, 17 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/pmu.h b/arch/arm64/include/asm/pmu.h
index e6f087806aaf..def95ff73d2b 100644
--- a/arch/arm64/include/asm/pmu.h
+++ b/arch/arm64/include/asm/pmu.h
@@ -64,6 +64,7 @@ struct arm_pmu {
 	u64			max_period;
 	struct platform_device	*plat_device;
 	struct pmu_hw_events	*(*get_hw_events)(void);
+	int			attr_rdpmc;
 };
 
 #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 70dcde67a808..b84c9366e332 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -607,6 +607,16 @@ static void armpmu_disable(struct pmu *pmu)
 	armpmu->stop();
 }
 
+static int armpmu_event_idx(struct perf_event *event)
+{
+	int idx = event->hw.idx;
+
+	if (!cpu_pmu->attr_rdpmc)
+		return 0;
+
+	return idx + 1;
+}
+
 static void __init armpmu_init(struct arm_pmu *armpmu)
 {
 	atomic_set(&armpmu->active_events, 0);
@@ -621,6 +631,7 @@ static void __init armpmu_init(struct arm_pmu *armpmu)
 		.start		= armpmu_start,
 		.stop		= armpmu_stop,
 		.read		= armpmu_read,
+		.event_idx	= armpmu_event_idx,
 	};
 }
 
@@ -1309,6 +1320,11 @@ static struct pmu_hw_events *armpmu_get_cpu_events(void)
 	return this_cpu_ptr(&cpu_hw_events);
 }
 
+void arch_perf_update_userpage(struct perf_event_mmap_page *userpg, u64 now)
+{
+	userpg->cap_user_rdpmc = cpu_pmu->attr_rdpmc;
+}
+
 static void __init cpu_pmu_init(struct arm_pmu *armpmu)
 {
 	int cpu;