[people/arne_f/kernel.git] / tools / arch / x86 / include / asm / cmpxchg.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef TOOLS_ASM_X86_CMPXCHG_H
#define TOOLS_ASM_X86_CMPXCHG_H

#include <linux/compiler.h>

/*
 * Non-existant functions to indicate usage errors at link time
 * (or compile-time if the compiler implements __compiletime_error().
 */
extern void __cmpxchg_wrong_size(void)
	__compiletime_error("Bad argument size for cmpxchg");

/*
 * 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 __x86_64__
#define __X86_CASE_Q	8
#else
#define	__X86_CASE_Q	-1		/* sizeof will never return -1 */
#endif

/*
 * 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 cmpxchg(ptr, old, new)						\
	__cmpxchg(ptr, old, new, sizeof(*(ptr)))


#endif	/* TOOLS_ASM_X86_CMPXCHG_H */
Commit	Line	Data
b2441318	1	/* SPDX-License-Identifier: GPL-2.0 */
3337e682 ACM	2	#ifndef TOOLS_ASM_X86_CMPXCHG_H
	3	#define TOOLS_ASM_X86_CMPXCHG_H
	4
	5	#include <linux/compiler.h>
	6
	7	/*
	8	* Non-existant functions to indicate usage errors at link time
	9	* (or compile-time if the compiler implements __compiletime_error().
	10	*/
	11	extern void __cmpxchg_wrong_size(void)
	12	__compiletime_error("Bad argument size for cmpxchg");
	13
	14	/*
	15	* Constants for operation sizes. On 32-bit, the 64-bit size it set to
	16	* -1 because sizeof will never return -1, thereby making those switch
	17	* case statements guaranteeed dead code which the compiler will
	18	* eliminate, and allowing the "missing symbol in the default case" to
	19	* indicate a usage error.
	20	*/
	21	#define __X86_CASE_B 1
	22	#define __X86_CASE_W 2
	23	#define __X86_CASE_L 4
	24	#ifdef __x86_64__
	25	#define __X86_CASE_Q 8
	26	#else
	27	#define __X86_CASE_Q -1 /* sizeof will never return -1 */
	28	#endif
	29
	30	/*
	31	* Atomic compare and exchange. Compare OLD with MEM, if identical,
	32	* store NEW in MEM. Return the initial value in MEM. Success is
	33	* indicated by comparing RETURN with OLD.
	34	*/
	35	#define __raw_cmpxchg(ptr, old, new, size, lock) \
	36	({ \
	37	__typeof__(*(ptr)) __ret; \
	38	__typeof__(*(ptr)) __old = (old); \
	39	__typeof__(*(ptr)) __new = (new); \
	40	switch (size) { \
	41	case __X86_CASE_B: \
	42	{ \
	43	volatile u8 __ptr = (volatile u8 )(ptr); \
	44	asm volatile(lock "cmpxchgb %2,%1" \
	45	: "=a" (__ret), "+m" (*__ptr) \
	46	: "q" (__new), "0" (__old) \
	47	: "memory"); \
	48	break; \
	49	} \
	50	case __X86_CASE_W: \
	51	{ \
	52	volatile u16 __ptr = (volatile u16 )(ptr); \
	53	asm volatile(lock "cmpxchgw %2,%1" \
	54	: "=a" (__ret), "+m" (*__ptr) \
	55	: "r" (__new), "0" (__old) \
	56	: "memory"); \
	57	break; \
	58	} \
	59	case __X86_CASE_L: \
	60	{ \
	61	volatile u32 __ptr = (volatile u32 )(ptr); \
	62	asm volatile(lock "cmpxchgl %2,%1" \
	63	: "=a" (__ret), "+m" (*__ptr) \
	64	: "r" (__new), "0" (__old) \
	65	: "memory"); \
66	break; \
67	} \
68	case __X86_CASE_Q: \
69	{ \
70	volatile u64 __ptr = (volatile u64 )(ptr); \
71	asm volatile(lock "cmpxchgq %2,%1" \
72	: "=a" (__ret), "+m" (*__ptr) \
73	: "r" (__new), "0" (__old) \
74	: "memory"); \
75	break; \
76	} \
77	default: \
78	__cmpxchg_wrong_size(); \
79	} \
80	__ret; \
81	})
82
83	#define __cmpxchg(ptr, old, new, size) \
84	__raw_cmpxchg((ptr), (old), (new), (size), LOCK_PREFIX)
85
86	#define cmpxchg(ptr, old, new) \
87	__cmpxchg(ptr, old, new, sizeof(*(ptr)))
88
89
90	#endif /* TOOLS_ASM_X86_CMPXCHG_H */