Implement atomic_{set,clear}bits_int and membars for arm64.

With feedback from Dale Rahn, ok patrick@.

1 files changed, 44 insertions, 19 deletions

diff --git a/sys/arch/arm64/include/atomic.h b/sys/arch/arm64/include/atomic.h
index 0c19c752bac..7de934ca7d0 100644
--- a/sys/arch/arm64/include/atomic.h
+++ b/sys/arch/arm64/include/atomic.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: atomic.h,v 1.1 2016/12/17 23:38:33 patrick Exp $ */
+/* $OpenBSD: atomic.h,v 1.2 2017/02/04 04:17:43 jsg Exp $ */
 
 /* Public Domain */
 
@@ -6,34 +6,59 @@
 #define _MACHINE_ATOMIC_H_
 
 #if defined(_KERNEL)
-//#include <sys/stdatomic.h>
 
 #define __membar(_f) do { __asm __volatile(_f ::: "memory"); } while (0)
 
+#define membar_enter()		__membar("dmb sy")
+#define membar_exit()		__membar("dmb sy")
+#define membar_producer()	__membar("dmb st")
+#define membar_consumer()	__membar("dmb ld")
+#define membar_sync()		__membar("dmb sy")
+
 /* virtio needs MP membars even on SP kernels */
-#define virtio_membar_producer()	__membar("")
-#define virtio_membar_consumer()	__membar("")
-#define virtio_membar_sync()		__membar("dmb sy") /* XXX dmb? */
+#define virtio_membar_producer()	__membar("dmb st")
+#define virtio_membar_consumer()	__membar("dmb ld")
+#define virtio_membar_sync()		__membar("dmb sy")
 
+/*
+ * Set bits
+ * *p = *p | v
+ */
 static inline void
-atomic_setbits_int(__volatile unsigned int *ptr, unsigned int val)
+atomic_setbits_int(volatile unsigned int *p, unsigned int v)
 {
-#if 0
-	//FIXME
-	atomic_fetch_or_explicit((atomic_uint *)ptr, val, memory_order_seq_cst);
-#else
-	*ptr |= val;
-#endif
+	unsigned int modified, tmp;
+
+	__asm volatile (
+	    "1:	ldxr %w0, [%x3]		\n\t"
+	    "	orr %w0, %w0, %w2	\n\t"
+	    "	stxr %w1, %w0, [%x3]	\n\t"
+	    "	cbnz %w1, 1b		\n\t"
+	    : "=&r" (tmp), "=&r" (modified)
+	    : "r" (v), "r" (p)
+	    : "memory", "cc"
+	);
 }
+
+/*
+ * Clear bits
+ * *p = *p & (~v)
+ */
 static inline void
-atomic_clearbits_int(__volatile unsigned int *ptr, unsigned int val)
+atomic_clearbits_int(volatile unsigned int *p, unsigned int v)
 {
-#if 0
-	//FIXME
-	atomic_fetch_and_explicit((atomic_uint *)ptr, ~val, memory_order_seq_cst);
-#else
-	*ptr &= ~val;
-#endif
+	unsigned int modified, tmp;
+
+	__asm volatile (
+	    "1:	ldxr %w0, [%x3]		\n\t"
+	    "	bic %w0, %w0, %w2	\n\t"
+	    "	stxr %w1, %w0, [%x3]	\n\t"
+	    "	cbnz %w1, 1b		\n\t"
+	    : "=&r" (tmp), "=&r" (modified)
+	    : "r" (v), "r" (p)
+	    : "memory", "cc"
+	);
 }
+
 #endif /* defined(_KERNEL) */
 #endif /* _MACHINE_ATOMIC_H_ */