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
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