1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef __ASM_GENERIC_CMPXCHG_LOCAL_H 3 #define __ASM_GENERIC_CMPXCHG_LOCAL_H 4 5 #include <linux/types.h> 6 #include <linux/irqflags.h> 7 8 extern unsigned long wrong_size_cmpxchg(volatile void *ptr) 9 __noreturn; 10 11 /* 12 * Generic version of __cmpxchg_local (disables interrupts). Takes an unsigned 13 * long parameter, supporting various types of architectures. 14 */ 15 static 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 */ 54 static 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 #endif 69