Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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kernel
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linux
1#ifndef _LINUX_CONTEXT_TRACKING_H
2#define _LINUX_CONTEXT_TRACKING_H
3
4#include <linux/sched.h>
5#include <linux/percpu.h>
6#include <asm/ptrace.h>
7
8struct context_tracking {
9 /*
10 * When active is false, probes are unset in order
11 * to minimize overhead: TIF flags are cleared
12 * and calls to user_enter/exit are ignored. This
13 * may be further optimized using static keys.
14 */
15 bool active;
16 enum ctx_state {
17 IN_KERNEL = 0,
18 IN_USER,
19 } state;
20};
21
22#ifdef CONFIG_CONTEXT_TRACKING
23DECLARE_PER_CPU(struct context_tracking, context_tracking);
24
25static inline bool context_tracking_in_user(void)
26{
27 return __this_cpu_read(context_tracking.state) == IN_USER;
28}
29
30static inline bool context_tracking_active(void)
31{
32 return __this_cpu_read(context_tracking.active);
33}
34
35extern void user_enter(void);
36extern void user_exit(void);
37
38static inline enum ctx_state exception_enter(void)
39{
40 enum ctx_state prev_ctx;
41
42 prev_ctx = this_cpu_read(context_tracking.state);
43 user_exit();
44
45 return prev_ctx;
46}
47
48static inline void exception_exit(enum ctx_state prev_ctx)
49{
50 if (prev_ctx == IN_USER)
51 user_enter();
52}
53
54extern void context_tracking_task_switch(struct task_struct *prev,
55 struct task_struct *next);
56#else
57static inline bool context_tracking_in_user(void) { return false; }
58static inline void user_enter(void) { }
59static inline void user_exit(void) { }
60static inline enum ctx_state exception_enter(void) { return 0; }
61static inline void exception_exit(enum ctx_state prev_ctx) { }
62static inline void context_tracking_task_switch(struct task_struct *prev,
63 struct task_struct *next) { }
64#endif /* !CONFIG_CONTEXT_TRACKING */
65
66#endif