From 86f7743b596fcea904d31cd16d00183c3a661607 Mon Sep 17 00:00:00 2001
From: Raphael Poggi <poggi.raph@gmail.com>
Date: Thu, 1 Sep 2016 14:07:49 +0200
Subject: [PATCH] [arm64] enable cycle counter

---
 arch/arm64/include/arch/arch_ops.h | 8 ++++++++
 arch/arm64/mp.c                    | 4 ++++
 2 files changed, 12 insertions(+)

diff --git a/arch/arm64/include/arch/arch_ops.h b/arch/arm64/include/arch/arch_ops.h
index ee18c1c5b..8d2d2c601 100644
--- a/arch/arm64/include/arch/arch_ops.h
+++ b/arch/arm64/include/arch/arch_ops.h
@@ -233,6 +233,14 @@ static inline uint32_t arch_cycle_count(void)
                      : "=r" (count)
                     );
     return count;
+#elif ARM_ISA_ARMV8
+    uint32_t count;
+
+    ISB;
+    __asm__ volatile("mrs %0, pmccntr_el0"
+                     : "=r" (count)
+                    );
+    return count;
 #else
 //#warning no arch_cycle_count implementation
     return 0;
diff --git a/arch/arm64/mp.c b/arch/arm64/mp.c
index e3584c855..65358be97 100644
--- a/arch/arm64/mp.c
+++ b/arch/arm64/mp.c
@@ -81,6 +81,10 @@ enum handler_return arm_ipi_reschedule_handler(void *arg)
 
 void arch_mp_init_percpu(void)
 {
+    int pmcr_mask = 1;
+
+    __asm__ volatile("msr pmcr_el0, %0":: "r"(pmcr_mask):);
+
     register_int_handler(MP_IPI_GENERIC + GIC_IPI_BASE, &arm_ipi_generic_handler, 0);
     register_int_handler(MP_IPI_RESCHEDULE + GIC_IPI_BASE, &arm_ipi_reschedule_handler, 0);