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
arch_test_and_set_bit_lock(unsigned int nr,volatile unsigned long * p)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 = arch_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
arch_clear_bit_unlock(unsigned int nr,volatile unsigned long * p)41 arch_clear_bit_unlock(unsigned int nr, volatile unsigned long *p)
42 {
43 	p += BIT_WORD(nr);
44 	arch_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
arch___clear_bit_unlock(unsigned int nr,volatile unsigned long * p)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 	arch_atomic_long_set_release((atomic_long_t *)p, old);
67 }
68 
69 /**
70  * arch_clear_bit_unlock_is_negative_byte - Clear a bit in memory and test if bottom
71  *                                          byte is negative, for unlock.
72  * @nr: the bit to clear
73  * @addr: the address to start counting from
74  *
75  * This is a bit of a one-trick-pony for the filemap code, which clears
76  * PG_locked and tests PG_waiters,
77  */
78 #ifndef arch_clear_bit_unlock_is_negative_byte
arch_clear_bit_unlock_is_negative_byte(unsigned int nr,volatile unsigned long * p)79 static inline bool arch_clear_bit_unlock_is_negative_byte(unsigned int nr,
80 							  volatile unsigned long *p)
81 {
82 	long old;
83 	unsigned long mask = BIT_MASK(nr);
84 
85 	p += BIT_WORD(nr);
86 	old = arch_atomic_long_fetch_andnot_release(mask, (atomic_long_t *)p);
87 	return !!(old & BIT(7));
88 }
89 #define arch_clear_bit_unlock_is_negative_byte arch_clear_bit_unlock_is_negative_byte
90 #endif
91 
92 #include <asm-generic/bitops/instrumented-lock.h>
93 
94 #endif /* _ASM_GENERIC_BITOPS_LOCK_H_ */
95