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Diffstat (limited to 'arch/x86/include/asm/sync_bitops.h')
-rw-r--r-- | arch/x86/include/asm/sync_bitops.h | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/arch/x86/include/asm/sync_bitops.h b/arch/x86/include/asm/sync_bitops.h new file mode 100644 index 000000000000..9d09b4073b60 --- /dev/null +++ b/arch/x86/include/asm/sync_bitops.h @@ -0,0 +1,130 @@ +#ifndef _ASM_X86_SYNC_BITOPS_H +#define _ASM_X86_SYNC_BITOPS_H + +/* + * Copyright 1992, Linus Torvalds. + */ + +/* + * These have to be done with inline assembly: that way the bit-setting + * is guaranteed to be atomic. All bit operations return 0 if the bit + * was cleared before the operation and != 0 if it was not. + * + * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1). + */ + +#define ADDR (*(volatile long *)addr) + +/** + * sync_set_bit - Atomically set a bit in memory + * @nr: the bit to set + * @addr: the address to start counting from + * + * This function is atomic and may not be reordered. See __set_bit() + * if you do not require the atomic guarantees. + * + * Note that @nr may be almost arbitrarily large; this function is not + * restricted to acting on a single-word quantity. + */ +static inline void sync_set_bit(int nr, volatile unsigned long *addr) +{ + asm volatile("lock; btsl %1,%0" + : "+m" (ADDR) + : "Ir" (nr) + : "memory"); +} + +/** + * sync_clear_bit - Clears a bit in memory + * @nr: Bit to clear + * @addr: Address to start counting from + * + * sync_clear_bit() is atomic and may not be reordered. However, it does + * not contain a memory barrier, so if it is used for locking purposes, + * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit() + * in order to ensure changes are visible on other processors. + */ +static inline void sync_clear_bit(int nr, volatile unsigned long *addr) +{ + asm volatile("lock; btrl %1,%0" + : "+m" (ADDR) + : "Ir" (nr) + : "memory"); +} + +/** + * sync_change_bit - Toggle a bit in memory + * @nr: Bit to change + * @addr: Address to start counting from + * + * sync_change_bit() is atomic and may not be reordered. + * Note that @nr may be almost arbitrarily large; this function is not + * restricted to acting on a single-word quantity. + */ +static inline void sync_change_bit(int nr, volatile unsigned long *addr) +{ + asm volatile("lock; btcl %1,%0" + : "+m" (ADDR) + : "Ir" (nr) + : "memory"); +} + +/** + * sync_test_and_set_bit - Set a bit and return its old value + * @nr: Bit to set + * @addr: Address to count from + * + * This operation is atomic and cannot be reordered. + * It also implies a memory barrier. + */ +static inline int sync_test_and_set_bit(int nr, volatile unsigned long *addr) +{ + int oldbit; + + asm volatile("lock; btsl %2,%1\n\tsbbl %0,%0" + : "=r" (oldbit), "+m" (ADDR) + : "Ir" (nr) : "memory"); + return oldbit; +} + +/** + * sync_test_and_clear_bit - Clear a bit and return its old value + * @nr: Bit to clear + * @addr: Address to count from + * + * This operation is atomic and cannot be reordered. + * It also implies a memory barrier. + */ +static inline int sync_test_and_clear_bit(int nr, volatile unsigned long *addr) +{ + int oldbit; + + asm volatile("lock; btrl %2,%1\n\tsbbl %0,%0" + : "=r" (oldbit), "+m" (ADDR) + : "Ir" (nr) : "memory"); + return oldbit; +} + +/** + * sync_test_and_change_bit - Change a bit and return its old value + * @nr: Bit to change + * @addr: Address to count from + * + * This operation is atomic and cannot be reordered. + * It also implies a memory barrier. + */ +static inline int sync_test_and_change_bit(int nr, volatile unsigned long *addr) +{ + int oldbit; + + asm volatile("lock; btcl %2,%1\n\tsbbl %0,%0" + : "=r" (oldbit), "+m" (ADDR) + : "Ir" (nr) : "memory"); + return oldbit; +} + +#define sync_test_bit(nr, addr) test_bit(nr, addr) + +#undef ADDR + +#endif /* _ASM_X86_SYNC_BITOPS_H */ |