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1/* SPDX-License-Identifier: GPL-2.0 */2/*3 * Generic UP xchg and cmpxchg using interrupt disablement. Does not4 * support SMP.5 */6 7#ifndef __ASM_GENERIC_CMPXCHG_H8#define __ASM_GENERIC_CMPXCHG_H9 10#ifdef CONFIG_SMP11#error "Cannot use generic cmpxchg on SMP"12#endif13 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 if19 * something tries to do an invalidly-sized xchg().20 */21extern void __generic_xchg_called_with_bad_pointer(void);22 23static inline24unsigned 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_u831 return __xchg_u8(x, ptr);32#else33 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_u1642 return __xchg_u16(x, ptr);43#else44 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_u3253 return __xchg_u32(x, ptr);54#else55 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_64BIT63 case 8:64#ifdef __xchg_u6465 return __xchg_u64(x, ptr);66#else67 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_xchg101#define arch_xchg generic_xchg102#endif103 104#ifndef arch_cmpxchg_local105#define arch_cmpxchg_local generic_cmpxchg_local106#endif107 108#ifndef arch_cmpxchg64_local109#define arch_cmpxchg64_local generic_cmpxchg64_local110#endif111 112#define arch_cmpxchg arch_cmpxchg_local113#define arch_cmpxchg64 arch_cmpxchg64_local114 115#endif /* __ASM_GENERIC_CMPXCHG_H */116