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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * The Kernel Concurrency Sanitizer (KCSAN) infrastructure. For more info please
4 * see Documentation/dev-tools/kcsan.rst.
5 *
6 * Copyright (C) 2019, Google LLC.
7 */
8
9#ifndef _KERNEL_KCSAN_KCSAN_H
10#define _KERNEL_KCSAN_KCSAN_H
11
12#include <linux/atomic.h>
13#include <linux/kcsan.h>
14#include <linux/sched.h>
15
16/* The number of adjacent watchpoints to check. */
17#define KCSAN_CHECK_ADJACENT 1
18#define NUM_SLOTS (1 + 2*KCSAN_CHECK_ADJACENT)
19
20extern unsigned int kcsan_udelay_task;
21extern unsigned int kcsan_udelay_interrupt;
22
23/*
24 * Globally enable and disable KCSAN.
25 */
26extern bool kcsan_enabled;
27
28/*
29 * Save/restore IRQ flags state trace dirtied by KCSAN.
30 */
31void kcsan_save_irqtrace(struct task_struct *task);
32void kcsan_restore_irqtrace(struct task_struct *task);
33
34/*
35 * Statistics counters displayed via debugfs; should only be modified in
36 * slow-paths.
37 */
38enum kcsan_counter_id {
39 /*
40 * Number of watchpoints currently in use.
41 */
42 KCSAN_COUNTER_USED_WATCHPOINTS,
43
44 /*
45 * Total number of watchpoints set up.
46 */
47 KCSAN_COUNTER_SETUP_WATCHPOINTS,
48
49 /*
50 * Total number of data races.
51 */
52 KCSAN_COUNTER_DATA_RACES,
53
54 /*
55 * Total number of ASSERT failures due to races. If the observed race is
56 * due to two conflicting ASSERT type accesses, then both will be
57 * counted.
58 */
59 KCSAN_COUNTER_ASSERT_FAILURES,
60
61 /*
62 * Number of times no watchpoints were available.
63 */
64 KCSAN_COUNTER_NO_CAPACITY,
65
66 /*
67 * A thread checking a watchpoint raced with another checking thread;
68 * only one will be reported.
69 */
70 KCSAN_COUNTER_REPORT_RACES,
71
72 /*
73 * Observed data value change, but writer thread unknown.
74 */
75 KCSAN_COUNTER_RACES_UNKNOWN_ORIGIN,
76
77 /*
78 * The access cannot be encoded to a valid watchpoint.
79 */
80 KCSAN_COUNTER_UNENCODABLE_ACCESSES,
81
82 /*
83 * Watchpoint encoding caused a watchpoint to fire on mismatching
84 * accesses.
85 */
86 KCSAN_COUNTER_ENCODING_FALSE_POSITIVES,
87
88 KCSAN_COUNTER_COUNT, /* number of counters */
89};
90extern atomic_long_t kcsan_counters[KCSAN_COUNTER_COUNT];
91
92/*
93 * Returns true if data races in the function symbol that maps to func_addr
94 * (offsets are ignored) should *not* be reported.
95 */
96extern bool kcsan_skip_report_debugfs(unsigned long func_addr);
97
98/*
99 * Value-change states.
100 */
101enum kcsan_value_change {
102 /*
103 * Did not observe a value-change, however, it is valid to report the
104 * race, depending on preferences.
105 */
106 KCSAN_VALUE_CHANGE_MAYBE,
107
108 /*
109 * Did not observe a value-change, and it is invalid to report the race.
110 */
111 KCSAN_VALUE_CHANGE_FALSE,
112
113 /*
114 * The value was observed to change, and the race should be reported.
115 */
116 KCSAN_VALUE_CHANGE_TRUE,
117};
118
119/*
120 * The calling thread hit and consumed a watchpoint: set the access information
121 * to be consumed by the reporting thread. No report is printed yet.
122 */
123void kcsan_report_set_info(const volatile void *ptr, size_t size, int access_type,
124 unsigned long ip, int watchpoint_idx);
125
126/*
127 * The calling thread observed that the watchpoint it set up was hit and
128 * consumed: print the full report based on information set by the racing
129 * thread.
130 */
131void kcsan_report_known_origin(const volatile void *ptr, size_t size, int access_type,
132 unsigned long ip, enum kcsan_value_change value_change,
133 int watchpoint_idx, u64 old, u64 new, u64 mask);
134
135/*
136 * No other thread was observed to race with the access, but the data value
137 * before and after the stall differs. Reports a race of "unknown origin".
138 */
139void kcsan_report_unknown_origin(const volatile void *ptr, size_t size, int access_type,
140 unsigned long ip, u64 old, u64 new, u64 mask);
141
142#endif /* _KERNEL_KCSAN_KCSAN_H */