[MIPS] Type proof reimplementation of cmpxchg.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 107 insertions, 0 deletions

diff --git a/include/asm-mips/cmpxchg.h b/include/asm-mips/cmpxchg.h
new file mode 100644
index 00000000000..c5b4708e003
--- /dev/null
+++ b/include/asm-mips/cmpxchg.h
@@ -0,0 +1,107 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2003, 06, 07 by Ralf Baechle (ralf@linux-mips.org)
+ */
+#ifndef __ASM_CMPXCHG_H
+#define __ASM_CMPXCHG_H
+
+#include <linux/irqflags.h>
+
+#define __HAVE_ARCH_CMPXCHG 1
+
+#define __cmpxchg_asm(ld, st, m, old, new)				\
+({									\
+	__typeof(*(m)) __ret;						\
+									\
+	if (cpu_has_llsc && R10000_LLSC_WAR) {				\
+		__asm__ __volatile__(					\
+		"	.set	push				\n"	\
+		"	.set	noat				\n"	\
+		"	.set	mips3				\n"	\
+		"1:	" ld "	%0, %2		# __cmpxchg_asm	\n"	\
+		"	bne	%0, %z3, 2f			\n"	\
+		"	.set	mips0				\n"	\
+		"	move	$1, %z4				\n"	\
+		"	.set	mips3				\n"	\
+		"	" st "	$1, %1				\n"	\
+		"	beqzl	$1, 1b				\n"	\
+		"2:						\n"	\
+		"	.set	pop				\n"	\
+		: "=&r" (__ret), "=R" (*m)				\
+		: "R" (*m), "Jr" (old), "Jr" (new)			\
+		: "memory");						\
+	} else if (cpu_has_llsc) {					\
+		__asm__ __volatile__(					\
+		"	.set	push				\n"	\
+		"	.set	noat				\n"	\
+		"	.set	mips3				\n"	\
+		"1:	" ld "	%0, %2		# __cmpxchg_asm	\n"	\
+		"	bne	%0, %z3, 2f			\n"	\
+		"	.set	mips0				\n"	\
+		"	move	$1, %z4				\n"	\
+		"	.set	mips3				\n"	\
+		"	" st "	$1, %1				\n"	\
+		"	beqz	$1, 3f				\n"	\
+		"2:						\n"	\
+		"	.subsection 2				\n"	\
+		"3:	b	1b				\n"	\
+		"	.previous				\n"	\
+		"	.set	pop				\n"	\
+		: "=&r" (__ret), "=R" (*m)				\
+		: "R" (*m), "Jr" (old), "Jr" (new)			\
+		: "memory");						\
+	} else {							\
+		unsigned long __flags;					\
+									\
+		raw_local_irq_save(__flags);				\
+		__ret = *m;						\
+		if (__ret == old)					\
+			*m = new;					\
+		raw_local_irq_restore(__flags);				\
+	}								\
+									\
+	__ret;								\
+})
+
+/*
+ * This function doesn't exist, so you'll get a linker error
+ * if something tries to do an invalid cmpxchg().
+ */
+extern void __cmpxchg_called_with_bad_pointer(void);
+
+#define __cmpxchg(ptr,old,new,barrier)					\
+({									\
+	__typeof__(ptr) __ptr = (ptr);					\
+	__typeof__(*(ptr)) __old = (old);				\
+	__typeof__(*(ptr)) __new = (new);				\
+	__typeof__(*(ptr)) __res = 0;					\
+									\
+	barrier;							\
+									\
+	switch (sizeof(*(__ptr))) {					\
+	case 4:								\
+		__res = __cmpxchg_asm("ll", "sc", __ptr, __old, __new);	\
+		break;							\
+	case 8:								\
+		if (sizeof(long) == 8) {				\
+			__res = __cmpxchg_asm("lld", "scd", __ptr,	\
+					   __old, __new);		\
+			break;						\
+		}							\
+	default:							\
+		__cmpxchg_called_with_bad_pointer();			\
+		break;							\
+	}								\
+									\
+	barrier;							\
+									\
+	__res;								\
+})
+
+#define cmpxchg(ptr, old, new)		__cmpxchg(ptr, old, new, smp_llsc_mb())
+#define cmpxchg_local(ptr, old, new)	__cmpxchg(ptr, old, new,)
+
+#endif /* __ASM_CMPXCHG_H */