Merge tag 'for-linus-20130509' of git://git.infradead.org/~dwmw2/random-2.6
[platform/adaptation/renesas_rcar/renesas_kernel.git] / include / linux / context_tracking.h
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
8 struct 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
23 DECLARE_PER_CPU(struct context_tracking, context_tracking);
24
25 static inline bool context_tracking_in_user(void)
26 {
27         return __this_cpu_read(context_tracking.state) == IN_USER;
28 }
29
30 static inline bool context_tracking_active(void)
31 {
32         return __this_cpu_read(context_tracking.active);
33 }
34
35 extern void user_enter(void);
36 extern void user_exit(void);
37
38 static 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
48 static inline void exception_exit(enum ctx_state prev_ctx)
49 {
50         if (prev_ctx == IN_USER)
51                 user_enter();
52 }
53
54 extern void context_tracking_task_switch(struct task_struct *prev,
55                                          struct task_struct *next);
56 #else
57 static inline bool context_tracking_in_user(void) { return false; }
58 static inline void user_enter(void) { }
59 static inline void user_exit(void) { }
60 static inline enum ctx_state exception_enter(void) { return 0; }
61 static inline void exception_exit(enum ctx_state prev_ctx) { }
62 static inline void context_tracking_task_switch(struct task_struct *prev,
63                                                 struct task_struct *next) { }
64 #endif /* !CONFIG_CONTEXT_TRACKING */
65
66 #endif