1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * Generic UP xchg and cmpxchg using interrupt disablement.  Does not
  4 * support SMP.
  5 */
  6
  7#ifndef __ASM_GENERIC_CMPXCHG_H
  8#define __ASM_GENERIC_CMPXCHG_H
  9
 10#ifdef CONFIG_SMP
 11#error "Cannot use generic cmpxchg on SMP"
 12#endif
 13
 14#include <linux/types.h>
 15#include <linux/irqflags.h>
 16
 17/*
 18 * This function doesn't exist, so you'll get a linker error if
 19 * something tries to do an invalidly-sized xchg().
 20 */
 21extern void __generic_xchg_called_with_bad_pointer(void);
 22
 23static inline
 24unsigned long __generic_xchg(unsigned long x, volatile void *ptr, int size)
 25{
 26	unsigned long ret, flags;
 27
 28	switch (size) {
 29	case 1:
 30#ifdef __xchg_u8
 31		return __xchg_u8(x, ptr);
 32#else
 33		local_irq_save(flags);
 34		ret = *(volatile u8 *)ptr;
 35		*(volatile u8 *)ptr = (x & 0xffu);
 36		local_irq_restore(flags);
 37		return ret;
 38#endif /* __xchg_u8 */
 39
 40	case 2:
 41#ifdef __xchg_u16
 42		return __xchg_u16(x, ptr);
 43#else
 44		local_irq_save(flags);
 45		ret = *(volatile u16 *)ptr;
 46		*(volatile u16 *)ptr = (x & 0xffffu);
 47		local_irq_restore(flags);
 48		return ret;
 49#endif /* __xchg_u16 */
 50
 51	case 4:
 52#ifdef __xchg_u32
 53		return __xchg_u32(x, ptr);
 54#else
 55		local_irq_save(flags);
 56		ret = *(volatile u32 *)ptr;
 57		*(volatile u32 *)ptr = (x & 0xffffffffu);
 58		local_irq_restore(flags);
 59		return ret;
 60#endif /* __xchg_u32 */
 61
 62#ifdef CONFIG_64BIT
 63	case 8:
 64#ifdef __xchg_u64
 65		return __xchg_u64(x, ptr);
 66#else
 67		local_irq_save(flags);
 68		ret = *(volatile u64 *)ptr;
 69		*(volatile u64 *)ptr = x;
 70		local_irq_restore(flags);
 71		return ret;
 72#endif /* __xchg_u64 */
 73#endif /* CONFIG_64BIT */
 74
 75	default:
 76		__generic_xchg_called_with_bad_pointer();
 77		return x;
 78	}
 79}
 80
 81#define generic_xchg(ptr, x) ({							\
 82	((__typeof__(*(ptr)))							\
 83		__generic_xchg((unsigned long)(x), (ptr), sizeof(*(ptr))));	\
 84})
 85
 86/*
 87 * Atomic compare and exchange.
 88 */
 89#include <asm-generic/cmpxchg-local.h>
 90
 91#define generic_cmpxchg_local(ptr, o, n) ({					\
 92	((__typeof__(*(ptr)))__generic_cmpxchg_local((ptr), (unsigned long)(o),	\
 93			(unsigned long)(n), sizeof(*(ptr))));			\
 94})
 95
 96#define generic_cmpxchg64_local(ptr, o, n) \
 97	__generic_cmpxchg64_local((ptr), (o), (n))
 98
 99
100#ifndef arch_xchg
101#define arch_xchg		generic_xchg
102#endif
103
104#ifndef arch_cmpxchg_local
105#define arch_cmpxchg_local	generic_cmpxchg_local
106#endif
107
108#ifndef arch_cmpxchg64_local
109#define arch_cmpxchg64_local	generic_cmpxchg64_local
110#endif
111
112#define arch_cmpxchg		arch_cmpxchg_local
113#define arch_cmpxchg64		arch_cmpxchg64_local
114
115#endif /* __ASM_GENERIC_CMPXCHG_H */

  1/* SPDX-License-Identifier: GPL-2.0 */
  2/*
  3 * Generic UP xchg and cmpxchg using interrupt disablement.  Does not
  4 * support SMP.
  5 */
  6
  7#ifndef __ASM_GENERIC_CMPXCHG_H
  8#define __ASM_GENERIC_CMPXCHG_H
  9
 10#ifdef CONFIG_SMP
 11#error "Cannot use generic cmpxchg on SMP"
 12#endif
 13
 14#include <linux/types.h>
 15#include <linux/irqflags.h>
 16
 17/*
 18 * This function doesn't exist, so you'll get a linker error if
 19 * something tries to do an invalidly-sized xchg().
 20 */
 21extern void __generic_xchg_called_with_bad_pointer(void);
 22
 23static inline
 24unsigned long __generic_xchg(unsigned long x, volatile void *ptr, int size)
 25{
 26	unsigned long ret, flags;
 27
 28	switch (size) {
 29	case 1:
 30#ifdef __xchg_u8
 31		return __xchg_u8(x, ptr);
 32#else
 33		local_irq_save(flags);
 34		ret = *(volatile u8 *)ptr;
 35		*(volatile u8 *)ptr = x;
 36		local_irq_restore(flags);
 37		return ret;
 38#endif /* __xchg_u8 */
 39
 40	case 2:
 41#ifdef __xchg_u16
 42		return __xchg_u16(x, ptr);
 43#else
 44		local_irq_save(flags);
 45		ret = *(volatile u16 *)ptr;
 46		*(volatile u16 *)ptr = x;
 47		local_irq_restore(flags);
 48		return ret;
 49#endif /* __xchg_u16 */
 50
 51	case 4:
 52#ifdef __xchg_u32
 53		return __xchg_u32(x, ptr);
 54#else
 55		local_irq_save(flags);
 56		ret = *(volatile u32 *)ptr;
 57		*(volatile u32 *)ptr = x;
 58		local_irq_restore(flags);
 59		return ret;
 60#endif /* __xchg_u32 */
 61
 62#ifdef CONFIG_64BIT
 63	case 8:
 64#ifdef __xchg_u64
 65		return __xchg_u64(x, ptr);
 66#else
 67		local_irq_save(flags);
 68		ret = *(volatile u64 *)ptr;
 69		*(volatile u64 *)ptr = x;
 70		local_irq_restore(flags);
 71		return ret;
 72#endif /* __xchg_u64 */
 73#endif /* CONFIG_64BIT */
 74
 75	default:
 76		__generic_xchg_called_with_bad_pointer();
 77		return x;
 78	}
 79}
 80
 81#define generic_xchg(ptr, x) ({							\
 82	((__typeof__(*(ptr)))							\
 83		__generic_xchg((unsigned long)(x), (ptr), sizeof(*(ptr))));	\
 84})
 85
 86/*
 87 * Atomic compare and exchange.
 88 */
 89#include <asm-generic/cmpxchg-local.h>
 90
 91#define generic_cmpxchg_local(ptr, o, n) ({					\
 92	((__typeof__(*(ptr)))__generic_cmpxchg_local((ptr), (unsigned long)(o),	\
 93			(unsigned long)(n), sizeof(*(ptr))));			\
 94})
 95
 96#define generic_cmpxchg64_local(ptr, o, n) \
 97	__generic_cmpxchg64_local((ptr), (o), (n))
 98
 99
100#ifndef arch_xchg
101#define arch_xchg		generic_xchg
102#endif
103
104#ifndef arch_cmpxchg_local
105#define arch_cmpxchg_local	generic_cmpxchg_local
106#endif
107
108#ifndef arch_cmpxchg64_local
109#define arch_cmpxchg64_local	generic_cmpxchg64_local
110#endif
111
112#define arch_cmpxchg		arch_cmpxchg_local
113#define arch_cmpxchg64		arch_cmpxchg64_local
114
115#endif /* __ASM_GENERIC_CMPXCHG_H */