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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef ASM_X86_CMPXCHG_H
#define ASM_X86_CMPXCHG_H
#include <linux/compiler.h>
#include <asm/cpufeatures.h>
#include <asm/alternative.h> /* Provides LOCK_PREFIX */
/*
* Non-existant functions to indicate usage errors at link time
* (or compile-time if the compiler implements __compiletime_error().
*/
extern void __xchg_wrong_size(void)
__compiletime_error("Bad argument size for xchg");
extern void __cmpxchg_wrong_size(void)
__compiletime_error("Bad argument size for cmpxchg");
extern void __xadd_wrong_size(void)
__compiletime_error("Bad argument size for xadd");
extern void __add_wrong_size(void)
__compiletime_error("Bad argument size for add");
/*
* Constants for operation sizes. On 32-bit, the 64-bit size it set to
* -1 because sizeof will never return -1, thereby making those switch
* case statements guaranteeed dead code which the compiler will
* eliminate, and allowing the "missing symbol in the default case" to
* indicate a usage error.
*/
#define __X86_CASE_B 1
#define __X86_CASE_W 2
#define __X86_CASE_L 4
#ifdef CONFIG_64BIT
#define __X86_CASE_Q 8
#else
#define __X86_CASE_Q -1 /* sizeof will never return -1 */
#endif
/*
* An exchange-type operation, which takes a value and a pointer, and
* returns the old value.
*/
#define __xchg_op(ptr, arg, op, lock) \
({ \
__typeof__ (*(ptr)) __ret = (arg); \
switch (sizeof(*(ptr))) { \
case __X86_CASE_B: \
asm volatile (lock #op "b %b0, %1\n" \
: "+q" (__ret), "+m" (*(ptr)) \
: : "memory", "cc"); \
break; \
case __X86_CASE_W: \
asm volatile (lock #op "w %w0, %1\n" \
: "+r" (__ret), "+m" (*(ptr)) \
: : "memory", "cc"); \
break; \
case __X86_CASE_L: \
asm volatile (lock #op "l %0, %1\n" \
: "+r" (__ret), "+m" (*(ptr)) \
: : "memory", "cc"); \
break; \
case __X86_CASE_Q: \
asm volatile (lock #op "q %q0, %1\n" \
: "+r" (__ret), "+m" (*(ptr)) \
: : "memory", "cc"); \
break; \
default: \
__ ## op ## _wrong_size(); \
} \
__ret; \
})
/*
* Note: no "lock" prefix even on SMP: xchg always implies lock anyway.
* Since this is generally used to protect other memory information, we
* use "asm volatile" and "memory" clobbers to prevent gcc from moving
* information around.
*/
#define xchg(ptr, v) __xchg_op((ptr), (v), xchg, "")
/*
* Atomic compare and exchange. Compare OLD with MEM, if identical,
* store NEW in MEM. Return the initial value in MEM. Success is
* indicated by comparing RETURN with OLD.
*/
#define __raw_cmpxchg(ptr, old, new, size, lock) \
({ \
__typeof__(*(ptr)) __ret; \
__typeof__(*(ptr)) __old = (old); \
__typeof__(*(ptr)) __new = (new); \
switch (size) { \
case __X86_CASE_B: \
{ \
volatile u8 *__ptr = (volatile u8 *)(ptr); \
asm volatile(lock "cmpxchgb %2,%1" \
: "=a" (__ret), "+m" (*__ptr) \
: "q" (__new), "0" (__old) \
: "memory"); \
break; \
} \
case __X86_CASE_W: \
{ \
volatile u16 *__ptr = (volatile u16 *)(ptr); \
asm volatile(lock "cmpxchgw %2,%1" \
: "=a" (__ret), "+m" (*__ptr) \
: "r" (__new), "0" (__old) \
: "memory"); \
break; \
} \
case __X86_CASE_L: \
{ \
volatile u32 *__ptr = (volatile u32 *)(ptr); \
asm volatile(lock "cmpxchgl %2,%1" \
: "=a" (__ret), "+m" (*__ptr) \
: "r" (__new), "0" (__old) \
: "memory"); \
break; \
} \
case __X86_CASE_Q: \
{ \
volatile u64 *__ptr = (volatile u64 *)(ptr); \
asm volatile(lock "cmpxchgq %2,%1" \
: "=a" (__ret), "+m" (*__ptr) \
: "r" (__new), "0" (__old) \
: "memory"); \
break; \
} \
default: \
__cmpxchg_wrong_size(); \
} \
__ret; \
})
#define __cmpxchg(ptr, old, new, size) \
__raw_cmpxchg((ptr), (old), (new), (size), LOCK_PREFIX)
#define __sync_cmpxchg(ptr, old, new, size) \
__raw_cmpxchg((ptr), (old), (new), (size), "lock; ")
#define __cmpxchg_local(ptr, old, new, size) \
__raw_cmpxchg((ptr), (old), (new), (size), "")
#ifdef CONFIG_X86_32
# include <asm/cmpxchg_32.h>
#else
# include <asm/cmpxchg_64.h>
#endif
#define cmpxchg(ptr, old, new) \
__cmpxchg(ptr, old, new, sizeof(*(ptr)))
#define sync_cmpxchg(ptr, old, new) \
__sync_cmpxchg(ptr, old, new, sizeof(*(ptr)))
#define cmpxchg_local(ptr, old, new) \
__cmpxchg_local(ptr, old, new, sizeof(*(ptr)))
#define __raw_try_cmpxchg(_ptr, _pold, _new, size, lock) \
({ \
bool success; \
__typeof__(_ptr) _old = (__typeof__(_ptr))(_pold); \
__typeof__(*(_ptr)) __old = *_old; \
__typeof__(*(_ptr)) __new = (_new); \
switch (size) { \
case __X86_CASE_B: \
{ \
volatile u8 *__ptr = (volatile u8 *)(_ptr); \
asm volatile(lock "cmpxchgb %[new], %[ptr]" \
CC_SET(z) \
: CC_OUT(z) (success), \
[ptr] "+m" (*__ptr), \
[old] "+a" (__old) \
: [new] "q" (__new) \
: "memory"); \
break; \
} \
case __X86_CASE_W: \
{ \
volatile u16 *__ptr = (volatile u16 *)(_ptr); \
asm volatile(lock "cmpxchgw %[new], %[ptr]" \
CC_SET(z) \
: CC_OUT(z) (success), \
[ptr] "+m" (*__ptr), \
[old] "+a" (__old) \
: [new] "r" (__new) \
: "memory"); \
break; \
} \
case __X86_CASE_L: \
{ \
volatile u32 *__ptr = (volatile u32 *)(_ptr); \
asm volatile(lock "cmpxchgl %[new], %[ptr]" \
CC_SET(z) \
: CC_OUT(z) (success), \
[ptr] "+m" (*__ptr), \
[old] "+a" (__old) \
: [new] "r" (__new) \
: "memory"); \
break; \
} \
case __X86_CASE_Q: \
{ \
volatile u64 *__ptr = (volatile u64 *)(_ptr); \
asm volatile(lock "cmpxchgq %[new], %[ptr]" \
CC_SET(z) \
: CC_OUT(z) (success), \
[ptr] "+m" (*__ptr), \
[old] "+a" (__old) \
: [new] "r" (__new) \
: "memory"); \
break; \
} \
default: \
__cmpxchg_wrong_size(); \
} \
if (unlikely(!success)) \
*_old = __old; \
likely(success); \
})
#define __try_cmpxchg(ptr, pold, new, size) \
__raw_try_cmpxchg((ptr), (pold), (new), (size), LOCK_PREFIX)
#define try_cmpxchg(ptr, pold, new) \
__try_cmpxchg((ptr), (pold), (new), sizeof(*(ptr)))
/*
* xadd() adds "inc" to "*ptr" and atomically returns the previous
* value of "*ptr".
*
* xadd() is locked when multiple CPUs are online
*/
#define __xadd(ptr, inc, lock) __xchg_op((ptr), (inc), xadd, lock)
#define xadd(ptr, inc) __xadd((ptr), (inc), LOCK_PREFIX)
#define __cmpxchg_double(pfx, p1, p2, o1, o2, n1, n2) \
({ \
bool __ret; \
__typeof__(*(p1)) __old1 = (o1), __new1 = (n1); \
__typeof__(*(p2)) __old2 = (o2), __new2 = (n2); \
BUILD_BUG_ON(sizeof(*(p1)) != sizeof(long)); \
BUILD_BUG_ON(sizeof(*(p2)) != sizeof(long)); \
VM_BUG_ON((unsigned long)(p1) % (2 * sizeof(long))); \
VM_BUG_ON((unsigned long)((p1) + 1) != (unsigned long)(p2)); \
asm volatile(pfx "cmpxchg%c4b %2; sete %0" \
: "=a" (__ret), "+d" (__old2), \
"+m" (*(p1)), "+m" (*(p2)) \
: "i" (2 * sizeof(long)), "a" (__old1), \
"b" (__new1), "c" (__new2)); \
__ret; \
})
#define cmpxchg_double(p1, p2, o1, o2, n1, n2) \
__cmpxchg_double(LOCK_PREFIX, p1, p2, o1, o2, n1, n2)
#define cmpxchg_double_local(p1, p2, o1, o2, n1, n2) \
__cmpxchg_double(, p1, p2, o1, o2, n1, n2)
#endif /* ASM_X86_CMPXCHG_H */
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