/arch/mips/include/asm/cmpxchg.h

  1/*
  2 * This file is subject to the terms and conditions of the GNU General Public
  3 * License.  See the file "COPYING" in the main directory of this archive
  4 * for more details.
  5 *
  6 * Copyright (C) 2003, 06, 07 by Ralf Baechle (ralf@linux-mips.org)
  7 */
  8#ifndef __ASM_CMPXCHG_H
  9#define __ASM_CMPXCHG_H
 10
 11#include <linux/irqflags.h>
 12
 13#define __HAVE_ARCH_CMPXCHG 1
 14
 15#define __cmpxchg_asm(ld, st, m, old, new)				\
 16({									\
 17	__typeof(*(m)) __ret;						\
 18									\
 19	if (kernel_uses_llsc && R10000_LLSC_WAR) {			\
 20		__asm__ __volatile__(					\
 21		"	.set	push				\n"	\
 22		"	.set	noat				\n"	\
 23		"	.set	mips3				\n"	\
 24		"1:	" ld "	%0, %2		# __cmpxchg_asm	\n"	\
 25		"	bne	%0, %z3, 2f			\n"	\
 26		"	.set	mips0				\n"	\
 27		"	move	$1, %z4				\n"	\
 28		"	.set	mips3				\n"	\
 29		"	" st "	$1, %1				\n"	\
 30		"	beqzl	$1, 1b				\n"	\
 31		"2:						\n"	\
 32		"	.set	pop				\n"	\
 33		: "=&r" (__ret), "=R" (*m)				\
 34		: "R" (*m), "Jr" (old), "Jr" (new)			\
 35		: "memory");						\
 36	} else if (kernel_uses_llsc) {					\
 37		__asm__ __volatile__(					\
 38		"	.set	push				\n"	\
 39		"	.set	noat				\n"	\
 40		"	.set	mips3				\n"	\
 41		"1:	" ld "	%0, %2		# __cmpxchg_asm	\n"	\
 42		"	bne	%0, %z3, 2f			\n"	\
 43		"	.set	mips0				\n"	\
 44		"	move	$1, %z4				\n"	\
 45		"	.set	mips3				\n"	\
 46		"	" st "	$1, %1				\n"	\
 47		"	beqz	$1, 3f				\n"	\
 48		"2:						\n"	\
 49		"	.subsection 2				\n"	\
 50		"3:	b	1b				\n"	\
 51		"	.previous				\n"	\
 52		"	.set	pop				\n"	\
 53		: "=&r" (__ret), "=R" (*m)				\
 54		: "R" (*m), "Jr" (old), "Jr" (new)			\
 55		: "memory");						\
 56	} else {							\
 57		unsigned long __flags;					\
 58									\
 59		raw_local_irq_save(__flags);				\
 60		__ret = *m;						\
 61		if (__ret == old)					\
 62			*m = new;					\
 63		raw_local_irq_restore(__flags);				\
 64	}								\
 65									\
 66	__ret;								\
 67})
 68
 69/*
 70 * This function doesn't exist, so you'll get a linker error
 71 * if something tries to do an invalid cmpxchg().
 72 */
 73extern void __cmpxchg_called_with_bad_pointer(void);
 74
 75#define __cmpxchg(ptr, old, new, pre_barrier, post_barrier)		\
 76({									\
 77	__typeof__(ptr) __ptr = (ptr);					\
 78	__typeof__(*(ptr)) __old = (old);				\
 79	__typeof__(*(ptr)) __new = (new);				\
 80	__typeof__(*(ptr)) __res = 0;					\
 81									\
 82	pre_barrier;							\
 83									\
 84	switch (sizeof(*(__ptr))) {					\
 85	case 4:								\
 86		__res = __cmpxchg_asm("ll", "sc", __ptr, __old, __new);	\
 87		break;							\
 88	case 8:								\
 89		if (sizeof(long) == 8) {				\
 90			__res = __cmpxchg_asm("lld", "scd", __ptr,	\
 91					   __old, __new);		\
 92			break;						\
 93		}							\
 94	default:							\
 95		__cmpxchg_called_with_bad_pointer();			\
 96		break;							\
 97	}								\
 98									\
 99	post_barrier;							\
100									\
101	__res;								\
102})
103
104#define cmpxchg(ptr, old, new)		__cmpxchg(ptr, old, new, smp_mb__before_llsc(), smp_llsc_mb())
105#define cmpxchg_local(ptr, old, new)	__cmpxchg(ptr, old, new, , )
106
107#define cmpxchg64(ptr, o, n)						\
108  ({									\
109	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
110	cmpxchg((ptr), (o), (n));					\
111  })
112
113#ifdef CONFIG_64BIT
114#define cmpxchg64_local(ptr, o, n)					\
115  ({									\
116	BUILD_BUG_ON(sizeof(*(ptr)) != 8);				\
117	cmpxchg_local((ptr), (o), (n));					\
118  })
119#else
120#include <asm-generic/cmpxchg-local.h>
121#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
122#endif
123
124#endif /* __ASM_CMPXCHG_H */