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1 : /* SPDX-License-Identifier: GPL-2.0 */
2 :
3 : /*
4 : * This file provides wrappers with sanitizer instrumentation for non-atomic
5 : * bit 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_NON_ATOMIC_H
12 : #define _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H
13 :
14 : #include <linux/instrumented.h>
15 :
16 : /**
17 : * ___set_bit - Set a bit in memory
18 : * @nr: the bit to set
19 : * @addr: the address to start counting from
20 : *
21 : * Unlike set_bit(), this function is non-atomic. If it is called on the same
22 : * region of memory concurrently, the effect may be that only one operation
23 : * succeeds.
24 : */
25 : static __always_inline void
26 : ___set_bit(unsigned long nr, volatile unsigned long *addr)
27 : {
28 24122 : instrument_write(addr + BIT_WORD(nr), sizeof(long));
29 12061 : arch___set_bit(nr, addr);
30 : }
31 :
32 : /**
33 : * ___clear_bit - Clears a bit in memory
34 : * @nr: the bit to clear
35 : * @addr: the address to start counting from
36 : *
37 : * Unlike clear_bit(), this function is non-atomic. If it is called on the same
38 : * region of memory concurrently, the effect may be that only one operation
39 : * succeeds.
40 : */
41 : static __always_inline void
42 : ___clear_bit(unsigned long nr, volatile unsigned long *addr)
43 : {
44 528064 : instrument_write(addr + BIT_WORD(nr), sizeof(long));
45 264032 : arch___clear_bit(nr, addr);
46 : }
47 :
48 : /**
49 : * ___change_bit - Toggle a bit in memory
50 : * @nr: the bit to change
51 : * @addr: the address to start counting from
52 : *
53 : * Unlike change_bit(), this function is non-atomic. If it is called on the same
54 : * region of memory concurrently, the effect may be that only one operation
55 : * succeeds.
56 : */
57 : static __always_inline void
58 : ___change_bit(unsigned long nr, volatile unsigned long *addr)
59 : {
60 0 : instrument_write(addr + BIT_WORD(nr), sizeof(long));
61 0 : arch___change_bit(nr, addr);
62 : }
63 :
64 : static __always_inline void __instrument_read_write_bitop(long nr, volatile unsigned long *addr)
65 : {
66 : if (IS_ENABLED(CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC)) {
67 : /*
68 : * We treat non-atomic read-write bitops a little more special.
69 : * Given the operations here only modify a single bit, assuming
70 : * non-atomicity of the writer is sufficient may be reasonable
71 : * for certain usage (and follows the permissible nature of the
72 : * assume-plain-writes-atomic rule):
73 : * 1. report read-modify-write races -> check read;
74 : * 2. do not report races with marked readers, but do report
75 : * races with unmarked readers -> check "atomic" write.
76 : */
77 : kcsan_check_read(addr + BIT_WORD(nr), sizeof(long));
78 : /*
79 : * Use generic write instrumentation, in case other sanitizers
80 : * or tools are enabled alongside KCSAN.
81 : */
82 : instrument_write(addr + BIT_WORD(nr), sizeof(long));
83 : } else {
84 2 : instrument_read_write(addr + BIT_WORD(nr), sizeof(long));
85 : }
86 : }
87 :
88 : /**
89 : * ___test_and_set_bit - Set a bit and return its old value
90 : * @nr: Bit to set
91 : * @addr: Address to count from
92 : *
93 : * This operation is non-atomic. If two instances of this operation race, one
94 : * can appear to succeed but actually fail.
95 : */
96 : static __always_inline bool
97 : ___test_and_set_bit(unsigned long nr, volatile unsigned long *addr)
98 : {
99 0 : __instrument_read_write_bitop(nr, addr);
100 0 : return arch___test_and_set_bit(nr, addr);
101 : }
102 :
103 : /**
104 : * ___test_and_clear_bit - Clear a bit and return its old value
105 : * @nr: Bit to clear
106 : * @addr: Address to count from
107 : *
108 : * This operation is non-atomic. If two instances of this operation race, one
109 : * can appear to succeed but actually fail.
110 : */
111 : static __always_inline bool
112 : ___test_and_clear_bit(unsigned long nr, volatile unsigned long *addr)
113 : {
114 2 : __instrument_read_write_bitop(nr, addr);
115 1 : return arch___test_and_clear_bit(nr, addr);
116 : }
117 :
118 : /**
119 : * ___test_and_change_bit - Change a bit and return its old value
120 : * @nr: Bit to change
121 : * @addr: Address to count from
122 : *
123 : * This operation is non-atomic. If two instances of this operation race, one
124 : * can appear to succeed but actually fail.
125 : */
126 : static __always_inline bool
127 : ___test_and_change_bit(unsigned long nr, volatile unsigned long *addr)
128 : {
129 : __instrument_read_write_bitop(nr, addr);
130 : return arch___test_and_change_bit(nr, addr);
131 : }
132 :
133 : /**
134 : * _test_bit - Determine whether a bit is set
135 : * @nr: bit number to test
136 : * @addr: Address to start counting from
137 : */
138 : static __always_inline bool
139 : _test_bit(unsigned long nr, const volatile unsigned long *addr)
140 : {
141 111044 : instrument_atomic_read(addr + BIT_WORD(nr), sizeof(long));
142 55522 : return arch_test_bit(nr, addr);
143 : }
144 :
145 : /**
146 : * _test_bit_acquire - Determine, with acquire semantics, whether a bit is set
147 : * @nr: bit number to test
148 : * @addr: Address to start counting from
149 : */
150 : static __always_inline bool
151 : _test_bit_acquire(unsigned long nr, const volatile unsigned long *addr)
152 : {
153 0 : instrument_atomic_read(addr + BIT_WORD(nr), sizeof(long));
154 0 : return arch_test_bit_acquire(nr, addr);
155 : }
156 :
157 : #endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H */
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