1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_GENERIC_BITOPS_LOCK_H_ 3 #define _ASM_GENERIC_BITOPS_LOCK_H_ 4 5 #include <linux/atomic.h> 6 #include <linux/compiler.h> 7 #include <asm/barrier.h> 8 9 /** 10 * arch_test_and_set_bit_lock - Set a bit and return its old value, for lock 11 * @nr: Bit to set 12 * @addr: Address to count from 13 * 14 * This operation is atomic and provides acquire barrier semantics if 15 * the returned value is 0. 16 * It can be used to implement bit locks. 17 */ 18 static __always_inline int 19 arch_test_and_set_bit_lock(unsigned int nr, volatile unsigned long *p) 20 { 21 long old; 22 unsigned long mask = BIT_MASK(nr); 23 24 p += BIT_WORD(nr); 25 if (READ_ONCE(*p) & mask) 26 return 1; 27 28 old = raw_atomic_long_fetch_or_acquire(mask, (atomic_long_t *)p); 29 return !!(old & mask); 30 } 31 32 33 /** 34 * arch_clear_bit_unlock - Clear a bit in memory, for unlock 35 * @nr: the bit to set 36 * @addr: the address to start counting from 37 * 38 * This operation is atomic and provides release barrier semantics. 39 */ 40 static __always_inline void 41 arch_clear_bit_unlock(unsigned int nr, volatile unsigned long *p) 42 { 43 p += BIT_WORD(nr); 44 raw_atomic_long_fetch_andnot_release(BIT_MASK(nr), (atomic_long_t *)p); 45 } 46 47 /** 48 * arch___clear_bit_unlock - Clear a bit in memory, for unlock 49 * @nr: the bit to set 50 * @addr: the address to start counting from 51 * 52 * A weaker form of clear_bit_unlock() as used by __bit_lock_unlock(). If all 53 * the bits in the word are protected by this lock some archs can use weaker 54 * ops to safely unlock. 55 * 56 * See for example x86's implementation. 57 */ 58 static inline void 59 arch___clear_bit_unlock(unsigned int nr, volatile unsigned long *p) 60 { 61 unsigned long old; 62 63 p += BIT_WORD(nr); 64 old = READ_ONCE(*p); 65 old &= ~BIT_MASK(nr); 66 raw_atomic_long_set_release((atomic_long_t *)p, old); 67 } 68 69 #ifndef arch_xor_unlock_is_negative_byte 70 static inline bool arch_xor_unlock_is_negative_byte(unsigned long mask, 71 volatile unsigned long *p) 72 { 73 long old; 74 75 old = raw_atomic_long_fetch_xor_release(mask, (atomic_long_t *)p); 76 return !!(old & BIT(7)); 77 } 78 #endif 79 80 #include <asm-generic/bitops/instrumented-lock.h> 81 82 #endif /* _ASM_GENERIC_BITOPS_LOCK_H_ */ 83