From 3b7a388b3e9c19e611f4ff9686fb72bf534cdf79 Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Mon, 6 Feb 2017 17:20:37 +0000
Subject: [PATCH] Update arm and arm64 counters MD bits.

On arm64 use atomics.  Then, both arm and arm64 do not need a critical
section around update.  Replace all cpus loop by CPU_FOREACH().
This brings arm and arm64 counter(9) implementation closer to current
amd64, but being more RISC-y, arm* version cannot avoid atomics.

Reported by:	Alexandre Martins <alexandre.martins@stormshield.eu>
Reviewed by:	andrew
Tested by:	Alexandre Martins, andrew
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
---
 sys/arm/include/counter.h   | 18 +++++-------------
 sys/arm64/include/counter.h | 20 ++++++--------------
 2 files changed, 11 insertions(+), 27 deletions(-)

diff --git a/sys/arm/include/counter.h b/sys/arm/include/counter.h
index c4da91f7a14..950516e1616 100644
--- a/sys/arm/include/counter.h
+++ b/sys/arm/include/counter.h
@@ -31,12 +31,9 @@
 
 #include <sys/pcpu.h>
 #include <machine/atomic.h>
-#ifdef INVARIANTS
-#include <sys/proc.h>
-#endif
 
-#define	counter_enter()	critical_enter()
-#define	counter_exit()	critical_exit()
+#define	counter_enter()	do {} while (0)
+#define	counter_exit()	do {} while (0)
 
 #ifdef IN_SUBR_COUNTER_C
 
@@ -55,7 +52,7 @@ counter_u64_fetch_inline(uint64_t *p)
 	int i;
 
 	r = 0;
-	for (i = 0; i < mp_ncpus; i++)
+	CPU_FOREACH(i)
 		r += counter_u64_read_one((uint64_t *)p, i);
 
 	return (r);
@@ -78,18 +75,13 @@ counter_u64_zero_inline(counter_u64_t c)
 }
 #endif
 
-#define	counter_u64_add_protected(c, inc)	do {	\
-	CRITICAL_ASSERT(curthread);			\
-	atomic_add_64((uint64_t *)zpcpu_get(c), (inc));	\
-} while (0)
+#define	counter_u64_add_protected(c, inc)	counter_u64_add(c, inc)
 
 static inline void
 counter_u64_add(counter_u64_t c, int64_t inc)
 {
 
-	counter_enter();
-	counter_u64_add_protected(c, inc);
-	counter_exit();
+	atomic_add_64((uint64_t *)zpcpu_get(c), inc);
 }
 
 #endif	/* ! __MACHINE_COUNTER_H__ */
diff --git a/sys/arm64/include/counter.h b/sys/arm64/include/counter.h
index 9d56cce3d3d..cfa521f9b73 100644
--- a/sys/arm64/include/counter.h
+++ b/sys/arm64/include/counter.h
@@ -30,12 +30,10 @@
 #define	_MACHINE_COUNTER_H_
 
 #include <sys/pcpu.h>
-#ifdef INVARIANTS
-#include <sys/proc.h>
-#endif
+#include <machine/atomic.h>
 
-#define	counter_enter()	critical_enter()
-#define	counter_exit()	critical_exit()
+#define	counter_enter()	do {} while (0)
+#define	counter_exit()	do {} while (0)
 
 #ifdef IN_SUBR_COUNTER_C
 static inline uint64_t
@@ -52,13 +50,12 @@ counter_u64_fetch_inline(uint64_t *p)
 	int i;
 
 	r = 0;
-	for (i = 0; i < mp_ncpus; i++)
+	CPU_FOREACH(i)
 		r += counter_u64_read_one((uint64_t *)p, i);
 
 	return (r);
 }
 
-/* XXXKIB might interrupt increment */
 static void
 counter_u64_zero_one_cpu(void *arg)
 {
@@ -76,18 +73,13 @@ counter_u64_zero_inline(counter_u64_t c)
 }
 #endif
 
-#define	counter_u64_add_protected(c, inc)	do {	\
-	CRITICAL_ASSERT(curthread);			\
-	*(uint64_t *)zpcpu_get(c) += (inc);		\
-} while (0)
+#define	counter_u64_add_protected(c, inc)	counter_u64_add(c, inc)
 
 static inline void
 counter_u64_add(counter_u64_t c, int64_t inc)
 {
 
-	counter_enter();
-	counter_u64_add_protected(c, inc);
-	counter_exit();
+	atomic_add_64((uint64_t *)zpcpu_get(c), inc);
 }
 
 #endif	/* ! _MACHINE_COUNTER_H_ */