summaryrefslogtreecommitdiff
path: root/include/asm-generic/bitops/instrumented-non-atomic.h
blob: 988a3bbfba34ec9a1b4904520a5cadc469842dbd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
/* SPDX-License-Identifier: GPL-2.0 */

/*
 * This file provides wrappers with sanitizer instrumentation for non-atomic
 * bit operations.
 *
 * To use this functionality, an arch's bitops.h file needs to define each of
 * the below bit operations with an arch_ prefix (e.g. arch_set_bit(),
 * arch___set_bit(), etc.).
 */
#ifndef _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H
#define _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H

#include <linux/instrumented.h>

/**
 * ___set_bit - Set a bit in memory
 * @nr: the bit to set
 * @addr: the address to start counting from
 *
 * Unlike set_bit(), this function is non-atomic. If it is called on the same
 * region of memory concurrently, the effect may be that only one operation
 * succeeds.
 */
static __always_inline void
___set_bit(unsigned long nr, volatile unsigned long *addr)
{
	instrument_write(addr + BIT_WORD(nr), sizeof(long));
	arch___set_bit(nr, addr);
}

/**
 * ___clear_bit - Clears a bit in memory
 * @nr: the bit to clear
 * @addr: the address to start counting from
 *
 * Unlike clear_bit(), this function is non-atomic. If it is called on the same
 * region of memory concurrently, the effect may be that only one operation
 * succeeds.
 */
static __always_inline void
___clear_bit(unsigned long nr, volatile unsigned long *addr)
{
	instrument_write(addr + BIT_WORD(nr), sizeof(long));
	arch___clear_bit(nr, addr);
}

/**
 * ___change_bit - Toggle a bit in memory
 * @nr: the bit to change
 * @addr: the address to start counting from
 *
 * Unlike change_bit(), this function is non-atomic. If it is called on the same
 * region of memory concurrently, the effect may be that only one operation
 * succeeds.
 */
static __always_inline void
___change_bit(unsigned long nr, volatile unsigned long *addr)
{
	instrument_write(addr + BIT_WORD(nr), sizeof(long));
	arch___change_bit(nr, addr);
}

static __always_inline void __instrument_read_write_bitop(long nr, volatile unsigned long *addr)
{
	if (IS_ENABLED(CONFIG_KCSAN_ASSUME_PLAIN_WRITES_ATOMIC)) {
		/*
		 * We treat non-atomic read-write bitops a little more special.
		 * Given the operations here only modify a single bit, assuming
		 * non-atomicity of the writer is sufficient may be reasonable
		 * for certain usage (and follows the permissible nature of the
		 * assume-plain-writes-atomic rule):
		 * 1. report read-modify-write races -> check read;
		 * 2. do not report races with marked readers, but do report
		 *    races with unmarked readers -> check "atomic" write.
		 */
		kcsan_check_read(addr + BIT_WORD(nr), sizeof(long));
		/*
		 * Use generic write instrumentation, in case other sanitizers
		 * or tools are enabled alongside KCSAN.
		 */
		instrument_write(addr + BIT_WORD(nr), sizeof(long));
	} else {
		instrument_read_write(addr + BIT_WORD(nr), sizeof(long));
	}
}

/**
 * ___test_and_set_bit - Set a bit and return its old value
 * @nr: Bit to set
 * @addr: Address to count from
 *
 * This operation is non-atomic. If two instances of this operation race, one
 * can appear to succeed but actually fail.
 */
static __always_inline bool
___test_and_set_bit(unsigned long nr, volatile unsigned long *addr)
{
	__instrument_read_write_bitop(nr, addr);
	return arch___test_and_set_bit(nr, addr);
}

/**
 * ___test_and_clear_bit - Clear a bit and return its old value
 * @nr: Bit to clear
 * @addr: Address to count from
 *
 * This operation is non-atomic. If two instances of this operation race, one
 * can appear to succeed but actually fail.
 */
static __always_inline bool
___test_and_clear_bit(unsigned long nr, volatile unsigned long *addr)
{
	__instrument_read_write_bitop(nr, addr);
	return arch___test_and_clear_bit(nr, addr);
}

/**
 * ___test_and_change_bit - Change a bit and return its old value
 * @nr: Bit to change
 * @addr: Address to count from
 *
 * This operation is non-atomic. If two instances of this operation race, one
 * can appear to succeed but actually fail.
 */
static __always_inline bool
___test_and_change_bit(unsigned long nr, volatile unsigned long *addr)
{
	__instrument_read_write_bitop(nr, addr);
	return arch___test_and_change_bit(nr, addr);
}

/**
 * _test_bit - Determine whether a bit is set
 * @nr: bit number to test
 * @addr: Address to start counting from
 */
static __always_inline bool
_test_bit(unsigned long nr, const volatile unsigned long *addr)
{
	instrument_atomic_read(addr + BIT_WORD(nr), sizeof(long));
	return arch_test_bit(nr, addr);
}

#endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H */