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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 unsigned long __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(unsigned long x, volatile void * ptr, int size)
{
switch (size) {
case 4:
return __xchg_asm("ll", "sc", (volatile u32 *)ptr, x);
case 8:
if (!IS_ENABLED(CONFIG_64BIT))
return __xchg_called_with_bad_pointer();
return __xchg_asm("lld", "scd", (volatile u64 *)ptr, x);
default:
return __xchg_called_with_bad_pointer();
}
}
#define xchg(ptr, x) \
({ \
__typeof__(*(ptr)) __res; \
\
BUILD_BUG_ON(sizeof(*(ptr)) & ~0xc); \
\
smp_mb__before_llsc(); \
\
__res = (__typeof__(*(ptr))) \
__xchg((unsigned long)(x), (ptr), sizeof(*(ptr))); \
\
smp_llsc_mb(); \
\
__res; \
})
#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; \
})
static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
unsigned long new, unsigned int size)
{
switch (size) {
case 4:
return __cmpxchg_asm("ll", "sc", (volatile u32 *)ptr, old, new);
case 8:
/* lld/scd are only available for MIPS64 */
if (!IS_ENABLED(CONFIG_64BIT))
return __cmpxchg_called_with_bad_pointer();
return __cmpxchg_asm("lld", "scd", (volatile u64 *)ptr, old, new);
default:
return __cmpxchg_called_with_bad_pointer();
}
}
#define cmpxchg_local(ptr, old, new) \
((__typeof__(*(ptr))) \
__cmpxchg((ptr), \
(unsigned long)(__typeof__(*(ptr)))(old), \
(unsigned long)(__typeof__(*(ptr)))(new), \
sizeof(*(ptr))))
#define cmpxchg(ptr, old, new) \
({ \
__typeof__(*(ptr)) __res; \
\
smp_mb__before_llsc(); \
__res = cmpxchg_local((ptr), (old), (new)); \
smp_llsc_mb(); \
\
__res; \
})
#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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