ARM64: perf: override arch_perf_userspace_access()

Override implementation of arch_perf_userspace_access() to enable
or disable access to "perf hw counter" from userspace for mmap

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

1 files changed, 6 insertions, 0 deletions

diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index 7c7dfe48d0f2..50412ad42d37 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -1394,6 +1394,12 @@ void arch_perf_update_userpage(struct perf_event_mmap_page *userpg, u64 now)
 	userpg->cap_user_rdpmc = cpu_pmu->attr_rdpmc;
 }
 
+void arch_perf_uspace_access(void *enable)
+{
+	cpu_pmu->attr_rdpmc = *(int *)enable;
+	asm volatile("msr pmuserenr_el0, %0" : : "r" (!!*(int *)enable));
+}
+
 static void __init cpu_pmu_init(struct arm_pmu *armpmu)
 {
 	int cpu;