69 lines · c
1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef __ASM_GENERIC_CMPXCHG_LOCAL_H3#define __ASM_GENERIC_CMPXCHG_LOCAL_H4 5#include <linux/types.h>6#include <linux/irqflags.h>7 8extern unsigned long wrong_size_cmpxchg(volatile void *ptr)9 __noreturn;10 11/*12 * Generic version of __cmpxchg_local (disables interrupts). Takes an unsigned13 * long parameter, supporting various types of architectures.14 */15static inline unsigned long __generic_cmpxchg_local(volatile void *ptr,16 unsigned long old, unsigned long new, int size)17{18 unsigned long flags, prev;19 20 /*21 * Sanity checking, compile-time.22 */23 if (size == 8 && sizeof(unsigned long) != 8)24 wrong_size_cmpxchg(ptr);25 26 raw_local_irq_save(flags);27 switch (size) {28 case 1: prev = *(u8 *)ptr;29 if (prev == (old & 0xffu))30 *(u8 *)ptr = (new & 0xffu);31 break;32 case 2: prev = *(u16 *)ptr;33 if (prev == (old & 0xffffu))34 *(u16 *)ptr = (new & 0xffffu);35 break;36 case 4: prev = *(u32 *)ptr;37 if (prev == (old & 0xffffffffu))38 *(u32 *)ptr = (new & 0xffffffffu);39 break;40 case 8: prev = *(u64 *)ptr;41 if (prev == old)42 *(u64 *)ptr = (u64)new;43 break;44 default:45 wrong_size_cmpxchg(ptr);46 }47 raw_local_irq_restore(flags);48 return prev;49}50 51/*52 * Generic version of __cmpxchg64_local. Takes an u64 parameter.53 */54static inline u64 __generic_cmpxchg64_local(volatile void *ptr,55 u64 old, u64 new)56{57 u64 prev;58 unsigned long flags;59 60 raw_local_irq_save(flags);61 prev = *(u64 *)ptr;62 if (prev == old)63 *(u64 *)ptr = new;64 raw_local_irq_restore(flags);65 return prev;66}67 68#endif69