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 
20 extern unsigned int kcsan_udelay_task;
21 extern unsigned int kcsan_udelay_interrupt;
22 
23 /*
24  * Globally enable and disable KCSAN.
25  */
26 extern bool kcsan_enabled;
27 
28 /*
29  * Save/restore IRQ flags state trace dirtied by KCSAN.
30  */
31 void kcsan_save_irqtrace(struct task_struct *task);
32 void kcsan_restore_irqtrace(struct task_struct *task);
33 
34 /*
35  * Statistics counters displayed via debugfs; should only be modified in
36  * slow-paths.
37  */
38 enum 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 };
90 extern 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  */
96 extern bool kcsan_skip_report_debugfs(unsigned long func_addr);
97 
98 /*
99  * Value-change states.
100  */
101 enum 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  */
123 void kcsan_report_set_info(const volatile void *ptr, size_t size, int access_type,
124 			   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  */
131 void kcsan_report_known_origin(const volatile void *ptr, size_t size, int access_type,
132 			       enum kcsan_value_change value_change, int watchpoint_idx,
133 			       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  */
139 void kcsan_report_unknown_origin(const volatile void *ptr, size_t size, int access_type,
140 				 u64 old, u64 new, u64 mask);
141 
142 #endif /* _KERNEL_KCSAN_KCSAN_H */
143