From 52b584bc157331a6a8b12a727172c5c6f49c8bfc Mon Sep 17 00:00:00 2001
From: Zbigniew Bodek <zbb@FreeBSD.org>
Date: Tue, 21 Jul 2015 12:50:45 +0000
Subject: [PATCH] Implement get_cyclecount() on ARM64

Use Vritual Counter register associated with Generic Timer to
read the cyclecount.

Obtained from: Semihalf
Sponsored by:  The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D3134
---
 sys/arm64/include/cpu.h | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/sys/arm64/include/cpu.h b/sys/arm64/include/cpu.h
index 33e2af65da4f..15cdd80d4e26 100644
--- a/sys/arm64/include/cpu.h
+++ b/sys/arm64/include/cpu.h
@@ -43,6 +43,7 @@
 
 #include <machine/atomic.h>
 #include <machine/frame.h>
+#include <machine/armreg.h>
 
 #define	TRAPF_PC(tfp)		((tfp)->tf_lr)
 #define	TRAPF_USERMODE(tfp)	(((tfp)->tf_elr & (1ul << 63)) == 0)
@@ -120,9 +121,11 @@ void	swi_vm(void *v);
 static __inline uint64_t
 get_cyclecount(void)
 {
+	uint64_t ret;
 
-	/* TODO: This is bogus */
-	return (1);
+	ret = READ_SPECIALREG(cntvct_el0);
+
+	return (ret);
 }
 
 #define	ADDRESS_TRANSLATE_FUNC(stage)				\