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/*
* 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/bug.h>
#include <linux/irqflags.h>
#include <asm/compiler.h>
#include <asm/war.h>
/*
* Using a branch-likely instruction to check the result of an sc instruction
* works around a bug present in R10000 CPUs prior to revision 3.0 that could
* cause ll-sc sequences to execute non-atomically.
*/
#if R10000_LLSC_WAR
# define __scbeqz "beqzl"
#else
# define __scbeqz "beqz"
#endif
/*
* These functions doesn't exist, so if they are called you'll either:
*
* - Get an error at compile-time due to __compiletime_error, if supported by
* your compiler.
*
* or:
*
* - Get an error at link-time due to the call to the missing function.
*/
extern void __cmpxchg_called_with_bad_pointer(void)
__compiletime_error("Bad argument size for cmpxchg");
extern unsigned long __xchg_called_with_bad_pointer(void)
__compiletime_error("Bad argument size for xchg");
#define __xchg_asm(ld, st, m, val) \
({ \
__typeof(*(m)) __ret; \
\
if (kernel_uses_llsc) { \
__asm__ __volatile__( \
" .set push \n" \
" .set noat \n" \
" .set " MIPS_ISA_ARCH_LEVEL " \n" \
"1: " ld " %0, %2 # __xchg_asm \n" \
" .set mips0 \n" \
" move $1, %z3 \n" \
" .set " MIPS_ISA_ARCH_LEVEL " \n" \
" " st " $1, %1 \n" \
"\t" __scbeqz " $1, 1b \n" \
" .set pop \n" \
: "=&r" (__ret), "=" GCC_OFF_SMALL_ASM() (*m) \
: GCC_OFF_SMALL_ASM() (*m), "Jr" (val) \
: "memory"); \
} else { \
unsigned long __flags; \
\
raw_local_irq_save(__flags); \
__ret = *m; \
*m = val; \
raw_local_irq_restore(__flags); \
} \
\
__ret; \
})
static inline unsigned long __xchg_u32(volatile int * m, unsigned int val)
{
__u32 retval;
smp_mb__before_llsc();
retval = __xchg_asm("ll", "sc", m, val);
smp_llsc_mb();
return retval;
}
#ifdef CONFIG_64BIT
static inline __u64 __xchg_u64(volatile __u64 * m, __u64 val)
{
__u64 retval;
smp_mb__before_llsc();
retval = __xchg_asm("lld", "scd", m, val);
smp_llsc_mb();
return retval;
}
#else
extern __u64 __xchg_u64_unsupported_on_32bit_kernels(volatile __u64 * m, __u64 val);
#define __xchg_u64 __xchg_u64_unsupported_on_32bit_kernels
#endif
static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
{
switch (size) {
case 4:
return __xchg_u32(ptr, x);
case 8:
return __xchg_u64(ptr, x);
default:
return __xchg_called_with_bad_pointer();
}
}
#define xchg(ptr, x) \
({ \
BUILD_BUG_ON(sizeof(*(ptr)) & ~0xc); \
\
((__typeof__(*(ptr))) \
__xchg((unsigned long)(x), (ptr), sizeof(*(ptr)))); \
})
#define __cmpxchg_asm(ld, st, m, old, new) \
({ \
__typeof(*(m)) __ret; \
\
if (kernel_uses_llsc) { \
__asm__ __volatile__( \
" .set push \n" \
" .set noat \n" \
" .set "MIPS_ISA_ARCH_LEVEL" \n" \
"1: " ld " %0, %2 # __cmpxchg_asm \n" \
" bne %0, %z3, 2f \n" \
" .set mips0 \n" \
" move $1, %z4 \n" \
" .set "MIPS_ISA_ARCH_LEVEL" \n" \
" " st " $1, %1 \n" \
"\t" __scbeqz " $1, 1b \n" \
" .set pop \n" \
"2: \n" \
: "=&r" (__ret), "=" GCC_OFF_SMALL_ASM() (*m) \
: GCC_OFF_SMALL_ASM() (*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; \
})
#define __cmpxchg(ptr, old, new, pre_barrier, post_barrier) \
({ \
__typeof__(ptr) __ptr = (ptr); \
__typeof__(*(ptr)) __old = (old); \
__typeof__(*(ptr)) __new = (new); \
__typeof__(*(ptr)) __res = 0; \
\
pre_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; \
} \
\
post_barrier; \
\
__res; \
})
#define cmpxchg(ptr, old, new) __cmpxchg(ptr, old, new, smp_mb__before_llsc(), smp_llsc_mb())
#define cmpxchg_local(ptr, old, new) __cmpxchg(ptr, old, new, , )
#ifdef CONFIG_64BIT
#define cmpxchg64_local(ptr, o, n) \
({ \
BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
cmpxchg_local((ptr), (o), (n)); \
})
#define cmpxchg64(ptr, o, n) \
({ \
BUILD_BUG_ON(sizeof(*(ptr)) != 8); \
cmpxchg((ptr), (o), (n)); \
})
#else
#include <asm-generic/cmpxchg-local.h>
#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
#define cmpxchg64(ptr, o, n) cmpxchg64_local((ptr), (o), (n))
#endif
#undef __scbeqz
#endif /* __ASM_CMPXCHG_H */
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