1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_CONTEXT_TRACKING_H
3 #define _LINUX_CONTEXT_TRACKING_H
4 
5 #include <linux/sched.h>
6 #include <linux/vtime.h>
7 #include <linux/context_tracking_state.h>
8 #include <linux/instrumentation.h>
9 
10 #include <asm/ptrace.h>
11 
12 
13 #ifdef CONFIG_CONTEXT_TRACKING_USER
14 extern void ct_cpu_track_user(int cpu);
15 
16 /* Called with interrupts disabled.  */
17 extern void __ct_user_enter(enum ctx_state state);
18 extern void __ct_user_exit(enum ctx_state state);
19 
20 extern void ct_user_enter(enum ctx_state state);
21 extern void ct_user_exit(enum ctx_state state);
22 
23 extern void user_enter_callable(void);
24 extern void user_exit_callable(void);
25 
26 static inline void user_enter(void)
27 {
28 	if (context_tracking_enabled())
29 		ct_user_enter(CT_STATE_USER);
30 
31 }
32 static inline void user_exit(void)
33 {
34 	if (context_tracking_enabled())
35 		ct_user_exit(CT_STATE_USER);
36 }
37 
38 /* Called with interrupts disabled.  */
39 static __always_inline void user_enter_irqoff(void)
40 {
41 	if (context_tracking_enabled())
42 		__ct_user_enter(CT_STATE_USER);
43 
44 }
45 static __always_inline void user_exit_irqoff(void)
46 {
47 	if (context_tracking_enabled())
48 		__ct_user_exit(CT_STATE_USER);
49 }
50 
51 static inline enum ctx_state exception_enter(void)
52 {
53 	enum ctx_state prev_ctx;
54 
55 	if (IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) ||
56 	    !context_tracking_enabled())
57 		return 0;
58 
59 	prev_ctx = __ct_state();
60 	if (prev_ctx != CT_STATE_KERNEL)
61 		ct_user_exit(prev_ctx);
62 
63 	return prev_ctx;
64 }
65 
66 static inline void exception_exit(enum ctx_state prev_ctx)
67 {
68 	if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) &&
69 	    context_tracking_enabled()) {
70 		if (prev_ctx != CT_STATE_KERNEL)
71 			ct_user_enter(prev_ctx);
72 	}
73 }
74 
75 static __always_inline bool context_tracking_guest_enter(void)
76 {
77 	if (context_tracking_enabled())
78 		__ct_user_enter(CT_STATE_GUEST);
79 
80 	return context_tracking_enabled_this_cpu();
81 }
82 
83 static __always_inline bool context_tracking_guest_exit(void)
84 {
85 	if (context_tracking_enabled())
86 		__ct_user_exit(CT_STATE_GUEST);
87 
88 	return context_tracking_enabled_this_cpu();
89 }
90 
91 #define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
92 
93 #else
94 static inline void user_enter(void) { }
95 static inline void user_exit(void) { }
96 static inline void user_enter_irqoff(void) { }
97 static inline void user_exit_irqoff(void) { }
98 static inline int exception_enter(void) { return 0; }
99 static inline void exception_exit(enum ctx_state prev_ctx) { }
100 static inline int ct_state(void) { return -1; }
101 static inline int __ct_state(void) { return -1; }
102 static __always_inline bool context_tracking_guest_enter(void) { return false; }
103 static __always_inline bool context_tracking_guest_exit(void) { return false; }
104 #define CT_WARN_ON(cond) do { } while (0)
105 #endif /* !CONFIG_CONTEXT_TRACKING_USER */
106 
107 #ifdef CONFIG_CONTEXT_TRACKING_USER_FORCE
108 extern void context_tracking_init(void);
109 #else
110 static inline void context_tracking_init(void) { }
111 #endif /* CONFIG_CONTEXT_TRACKING_USER_FORCE */
112 
113 #ifdef CONFIG_CONTEXT_TRACKING_IDLE
114 extern void ct_idle_enter(void);
115 extern void ct_idle_exit(void);
116 
117 /*
118  * Is RCU watching the current CPU (IOW, it is not in an extended quiescent state)?
119  *
120  * Note that this returns the actual boolean data (watching / not watching),
121  * whereas ct_rcu_watching() returns the RCU_WATCHING subvariable of
122  * context_tracking.state.
123  *
124  * No ordering, as we are sampling CPU-local information.
125  */
126 static __always_inline bool rcu_is_watching_curr_cpu(void)
127 {
128 	return raw_atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_RCU_WATCHING;
129 }
130 
131 /*
132  * Increment the current CPU's context_tracking structure's ->state field
133  * with ordering.  Return the new value.
134  */
135 static __always_inline unsigned long ct_state_inc(int incby)
136 {
137 	return raw_atomic_add_return(incby, this_cpu_ptr(&context_tracking.state));
138 }
139 
140 static __always_inline bool warn_rcu_enter(void)
141 {
142 	bool ret = false;
143 
144 	/*
145 	 * Horrible hack to shut up recursive RCU isn't watching fail since
146 	 * lots of the actual reporting also relies on RCU.
147 	 */
148 	preempt_disable_notrace();
149 	if (!rcu_is_watching_curr_cpu()) {
150 		ret = true;
151 		ct_state_inc(CT_RCU_WATCHING);
152 	}
153 
154 	return ret;
155 }
156 
157 static __always_inline void warn_rcu_exit(bool rcu)
158 {
159 	if (rcu)
160 		ct_state_inc(CT_RCU_WATCHING);
161 	preempt_enable_notrace();
162 }
163 
164 #else
165 static inline void ct_idle_enter(void) { }
166 static inline void ct_idle_exit(void) { }
167 
168 static __always_inline bool warn_rcu_enter(void) { return false; }
169 static __always_inline void warn_rcu_exit(bool rcu) { }
170 #endif /* !CONFIG_CONTEXT_TRACKING_IDLE */
171 
172 #endif
173