1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * The Kernel Concurrency Sanitizer (KCSAN) infrastructure. Public interface and
4 * data structures to set up runtime. See kcsan-checks.h for explicit checks and
5 * modifiers. For more info please see Documentation/dev-tools/kcsan.rst.
6 *
7 * Copyright (C) 2019, Google LLC.
8 */
9
10 #ifndef _LINUX_KCSAN_H
11 #define _LINUX_KCSAN_H
12
13 #include <linux/kcsan-checks.h>
14 #include <linux/types.h>
15
16 #ifdef CONFIG_KCSAN
17
18 /*
19 * Context for each thread of execution: for tasks, this is stored in
20 * task_struct, and interrupts access internal per-CPU storage.
21 */
22 struct kcsan_ctx {
23 int disable_count; /* disable counter */
24 int disable_scoped; /* disable scoped access counter */
25 int atomic_next; /* number of following atomic ops */
26
27 /*
28 * We distinguish between: (a) nestable atomic regions that may contain
29 * other nestable regions; and (b) flat atomic regions that do not keep
30 * track of nesting. Both (a) and (b) are entirely independent of each
31 * other, and a flat region may be started in a nestable region or
32 * vice-versa.
33 *
34 * This is required because, for example, in the annotations for
35 * seqlocks, we declare seqlock writer critical sections as (a) nestable
36 * atomic regions, but reader critical sections as (b) flat atomic
37 * regions, but have encountered cases where seqlock reader critical
38 * sections are contained within writer critical sections (the opposite
39 * may be possible, too).
40 *
41 * To support these cases, we independently track the depth of nesting
42 * for (a), and whether the leaf level is flat for (b).
43 */
44 int atomic_nest_count;
45 bool in_flat_atomic;
46
47 /*
48 * Access mask for all accesses if non-zero.
49 */
50 unsigned long access_mask;
51
52 /* List of scoped accesses; likely to be empty. */
53 struct list_head scoped_accesses;
54
55 #ifdef CONFIG_KCSAN_WEAK_MEMORY
56 /*
57 * Scoped access for modeling access reordering to detect missing memory
58 * barriers; only keep 1 to keep fast-path complexity manageable.
59 */
60 struct kcsan_scoped_access reorder_access;
61 #endif
62 };
63
64 /**
65 * kcsan_init - initialize KCSAN runtime
66 */
67 void kcsan_init(void);
68
69 #else /* CONFIG_KCSAN */
70
71 static inline void kcsan_init(void) { }
72
73 #endif /* CONFIG_KCSAN */
74
75 #endif /* _LINUX_KCSAN_H */
76
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