1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_KCOV_H
3 #define _LINUX_KCOV_H
4
5 #include <linux/sched.h>
6 #include <uapi/linux/kcov.h>
7
8 struct task_struct;
9
10 #ifdef CONFIG_KCOV
11
12 enum kcov_mode {
13 /* Coverage collection is not enabled yet. */
14 KCOV_MODE_DISABLED = 0,
15 /* KCOV was initialized, but tracing mode hasn't been chosen yet. */
16 KCOV_MODE_INIT = 1,
17 /*
18 * Tracing coverage collection mode.
19 * Covered PCs are collected in a per-task buffer.
20 */
21 KCOV_MODE_TRACE_PC = 2,
22 /* Collecting comparison operands mode. */
23 KCOV_MODE_TRACE_CMP = 3,
24 /* The process owns a KCOV remote reference. */
25 KCOV_MODE_REMOTE = 4,
26 };
27
28 #define KCOV_IN_CTXSW (1 << 30)
29
30 void kcov_task_init(struct task_struct *t);
31 void kcov_task_exit(struct task_struct *t);
32
33 #define kcov_prepare_switch(t) \
34 do { \
35 (t)->kcov_mode |= KCOV_IN_CTXSW; \
36 } while (0)
37
38 #define kcov_finish_switch(t) \
39 do { \
40 (t)->kcov_mode &= ~KCOV_IN_CTXSW; \
41 } while (0)
42
43 /* See Documentation/dev-tools/kcov.rst for usage details. */
44 void kcov_remote_start(u64 handle);
45 void kcov_remote_stop(void);
46 u64 kcov_common_handle(void);
47
48 static inline void kcov_remote_start_common(u64 id)
49 {
50 kcov_remote_start(kcov_remote_handle(KCOV_SUBSYSTEM_COMMON, id));
51 }
52
53 static inline void kcov_remote_start_usb(u64 id)
54 {
55 kcov_remote_start(kcov_remote_handle(KCOV_SUBSYSTEM_USB, id));
56 }
57
58 /*
59 * The softirq flavor of kcov_remote_*() functions is introduced as a temporary
60 * workaround for KCOV's lack of nested remote coverage sections support.
61 *
62 * Adding support is tracked in https://bugzilla.kernel.org/show_bug.cgi?id=210337.
63 *
64 * kcov_remote_start_usb_softirq():
65 *
66 * 1. Only collects coverage when called in the softirq context. This allows
67 * avoiding nested remote coverage collection sections in the task context.
68 * For example, USB/IP calls usb_hcd_giveback_urb() in the task context
69 * within an existing remote coverage collection section. Thus, KCOV should
70 * not attempt to start collecting coverage within the coverage collection
71 * section in __usb_hcd_giveback_urb() in this case.
72 *
73 * 2. Disables interrupts for the duration of the coverage collection section.
74 * This allows avoiding nested remote coverage collection sections in the
75 * softirq context (a softirq might occur during the execution of a work in
76 * the BH workqueue, which runs with in_serving_softirq() > 0).
77 * For example, usb_giveback_urb_bh() runs in the BH workqueue with
78 * interrupts enabled, so __usb_hcd_giveback_urb() might be interrupted in
79 * the middle of its remote coverage collection section, and the interrupt
80 * handler might invoke __usb_hcd_giveback_urb() again.
81 */
82
83 static inline unsigned long kcov_remote_start_usb_softirq(u64 id)
84 {
85 unsigned long flags = 0;
86
87 if (in_serving_softirq()) {
88 local_irq_save(flags);
89 kcov_remote_start_usb(id);
90 }
91
92 return flags;
93 }
94
95 static inline void kcov_remote_stop_softirq(unsigned long flags)
96 {
97 if (in_serving_softirq()) {
98 kcov_remote_stop();
99 local_irq_restore(flags);
100 }
101 }
102
103 #ifdef CONFIG_64BIT
104 typedef unsigned long kcov_u64;
105 #else
106 typedef unsigned long long kcov_u64;
107 #endif
108
109 void __sanitizer_cov_trace_pc(void);
110 void __sanitizer_cov_trace_cmp1(u8 arg1, u8 arg2);
111 void __sanitizer_cov_trace_cmp2(u16 arg1, u16 arg2);
112 void __sanitizer_cov_trace_cmp4(u32 arg1, u32 arg2);
113 void __sanitizer_cov_trace_cmp8(kcov_u64 arg1, kcov_u64 arg2);
114 void __sanitizer_cov_trace_const_cmp1(u8 arg1, u8 arg2);
115 void __sanitizer_cov_trace_const_cmp2(u16 arg1, u16 arg2);
116 void __sanitizer_cov_trace_const_cmp4(u32 arg1, u32 arg2);
117 void __sanitizer_cov_trace_const_cmp8(kcov_u64 arg1, kcov_u64 arg2);
118 void __sanitizer_cov_trace_switch(kcov_u64 val, void *cases);
119
120 #else
121
122 static inline void kcov_task_init(struct task_struct *t) {}
123 static inline void kcov_task_exit(struct task_struct *t) {}
124 static inline void kcov_prepare_switch(struct task_struct *t) {}
125 static inline void kcov_finish_switch(struct task_struct *t) {}
126 static inline void kcov_remote_start(u64 handle) {}
127 static inline void kcov_remote_stop(void) {}
128 static inline u64 kcov_common_handle(void)
129 {
130 return 0;
131 }
132 static inline void kcov_remote_start_common(u64 id) {}
133 static inline void kcov_remote_start_usb(u64 id) {}
134 static inline unsigned long kcov_remote_start_usb_softirq(u64 id)
135 {
136 return 0;
137 }
138 static inline void kcov_remote_stop_softirq(unsigned long flags) {}
139
140 #endif /* CONFIG_KCOV */
141 #endif /* _LINUX_KCOV_H */
142
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