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/instrumented.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  */
clear_bit_unlock(long nr,volatile unsigned long * addr)23 static inline void clear_bit_unlock(long nr, volatile unsigned long *addr)
24 {
25 	kcsan_release();
26 	instrument_atomic_write(addr + BIT_WORD(nr), sizeof(long));
27 	arch_clear_bit_unlock(nr, addr);
28 }
29 
30 /**
31  * __clear_bit_unlock - Clears a bit in memory
32  * @nr: Bit to clear
33  * @addr: Address to start counting from
34  *
35  * This is a non-atomic operation but implies a release barrier before the
36  * memory operation. It can be used for an unlock if no other CPUs can
37  * concurrently modify other bits in the word.
38  */
__clear_bit_unlock(long nr,volatile unsigned long * addr)39 static inline void __clear_bit_unlock(long nr, volatile unsigned long *addr)
40 {
41 	kcsan_release();
42 	instrument_write(addr + BIT_WORD(nr), sizeof(long));
43 	arch___clear_bit_unlock(nr, addr);
44 }
45 
46 /**
47  * test_and_set_bit_lock - Set a bit and return its old value, for lock
48  * @nr: Bit to set
49  * @addr: Address to count from
50  *
51  * This operation is atomic and provides acquire barrier semantics if
52  * the returned value is 0.
53  * It can be used to implement bit locks.
54  */
test_and_set_bit_lock(long nr,volatile unsigned long * addr)55 static inline bool test_and_set_bit_lock(long nr, volatile unsigned long *addr)
56 {
57 	instrument_atomic_read_write(addr + BIT_WORD(nr), sizeof(long));
58 	return arch_test_and_set_bit_lock(nr, addr);
59 }
60 
61 #if defined(arch_clear_bit_unlock_is_negative_byte)
62 /**
63  * clear_bit_unlock_is_negative_byte - Clear a bit in memory and test if bottom
64  *                                     byte is negative, for unlock.
65  * @nr: the bit to clear
66  * @addr: the address to start counting from
67  *
68  * This operation is atomic and provides release barrier semantics.
69  *
70  * This is a bit of a one-trick-pony for the filemap code, which clears
71  * PG_locked and tests PG_waiters,
72  */
73 static inline bool
clear_bit_unlock_is_negative_byte(long nr,volatile unsigned long * addr)74 clear_bit_unlock_is_negative_byte(long nr, volatile unsigned long *addr)
75 {
76 	kcsan_release();
77 	instrument_atomic_write(addr + BIT_WORD(nr), sizeof(long));
78 	return arch_clear_bit_unlock_is_negative_byte(nr, addr);
79 }
80 /* Let everybody know we have it. */
81 #define clear_bit_unlock_is_negative_byte clear_bit_unlock_is_negative_byte
82 #endif
83 
84 #endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_LOCK_H */
85