1 /* SPDX-License-Identifier: GPL-2.0 */
2 
3 /*
4  * This file provides wrappers with sanitizer instrumentation for bit
5  * locking operations.
6  *
7  * To use this functionality, an arch's bitops.h file needs to define each of
8  * the below bit operations with an arch_ prefix (e.g. arch_set_bit(),
9  * arch___set_bit(), etc.).
10  */
11 #ifndef _ASM_GENERIC_BITOPS_INSTRUMENTED_LOCK_H
12 #define _ASM_GENERIC_BITOPS_INSTRUMENTED_LOCK_H
13 
14 #include <linux/kasan-checks.h>
15 
16 /**
17  * clear_bit_unlock - Clear a bit in memory, for unlock
18  * @nr: the bit to set
19  * @addr: the address to start counting from
20  *
21  * This operation is atomic and provides release barrier semantics.
22  */
23 static inline void clear_bit_unlock(long nr, volatile unsigned long *addr)
24 {
25 	kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
26 	arch_clear_bit_unlock(nr, addr);
27 }
28 
29 /**
30  * __clear_bit_unlock - Clears a bit in memory
31  * @nr: Bit to clear
32  * @addr: Address to start counting from
33  *
34  * This is a non-atomic operation but implies a release barrier before the
35  * memory operation. It can be used for an unlock if no other CPUs can
36  * concurrently modify other bits in the word.
37  */
38 static inline void __clear_bit_unlock(long nr, volatile unsigned long *addr)
39 {
40 	kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
41 	arch___clear_bit_unlock(nr, addr);
42 }
43 
44 /**
45  * test_and_set_bit_lock - Set a bit and return its old value, for lock
46  * @nr: Bit to set
47  * @addr: Address to count from
48  *
49  * This operation is atomic and provides acquire barrier semantics if
50  * the returned value is 0.
51  * It can be used to implement bit locks.
52  */
53 static inline bool test_and_set_bit_lock(long nr, volatile unsigned long *addr)
54 {
55 	kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
56 	return arch_test_and_set_bit_lock(nr, addr);
57 }
58 
59 #if defined(arch_clear_bit_unlock_is_negative_byte)
60 /**
61  * clear_bit_unlock_is_negative_byte - Clear a bit in memory and test if bottom
62  *                                     byte is negative, for unlock.
63  * @nr: the bit to clear
64  * @addr: the address to start counting from
65  *
66  * This operation is atomic and provides release barrier semantics.
67  *
68  * This is a bit of a one-trick-pony for the filemap code, which clears
69  * PG_locked and tests PG_waiters,
70  */
71 static inline bool
72 clear_bit_unlock_is_negative_byte(long nr, volatile unsigned long *addr)
73 {
74 	kasan_check_write(addr + BIT_WORD(nr), sizeof(long));
75 	return arch_clear_bit_unlock_is_negative_byte(nr, addr);
76 }
77 /* Let everybody know we have it. */
78 #define clear_bit_unlock_is_negative_byte clear_bit_unlock_is_negative_byte
79 #endif
80 
81 #endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_LOCK_H */
82