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 */
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 */
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 */
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 /**
62 * xor_unlock_is_negative_byte - XOR a single byte in memory and test if
63 * it is negative, for unlock.
64 * @mask: Change the bits which are set in this mask.
65 * @addr: The address of the word containing the byte to change.
66 *
67 * Changes some of bits 0-6 in the word pointed to by @addr.
68 * This operation is atomic and provides release barrier semantics.
69 * Used to optimise some folio operations which are commonly paired
70 * with an unlock or end of writeback. Bit 7 is used as PG_waiters to
71 * indicate whether anybody is waiting for the unlock.
72 *
73 * Return: Whether the top bit of the byte is set.
74 */
75 static inline bool xor_unlock_is_negative_byte(unsigned long mask,
76 volatile unsigned long *addr)
77 {
78 kcsan_release();
79 instrument_atomic_write(addr, sizeof(long));
80 return arch_xor_unlock_is_negative_byte(mask, addr);
81 }
82 #endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_LOCK_H */
83
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