include/linux/context_tracking.h

   1 #ifndef _LINUX_CONTEXT_TRACKING_H
   2 #define _LINUX_CONTEXT_TRACKING_H
   3
   4 #ifdef CONFIG_CONTEXT_TRACKING
   5 #include <linux/sched.h>
   6 #include <linux/percpu.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 {
  17                 IN_KERNEL = 0,
  18                 IN_USER,
  19         } state;
  20 };
  21
  22 DECLARE_PER_CPU(struct context_tracking, context_tracking);
  23
  24 static inline bool context_tracking_in_user(void)
  25 {
  26         return __this_cpu_read(context_tracking.state) == IN_USER;
  27 }
  28
  29 static inline bool context_tracking_active(void)
  30 {
  31         return __this_cpu_read(context_tracking.active);
  32 }
  33
  34 extern void user_enter(void);
  35 extern void user_exit(void);
  36 extern void context_tracking_task_switch(struct task_struct *prev,
  37                                          struct task_struct *next);
  38 #else
  39 static inline bool context_tracking_in_user(void) { return false; }
  40 static inline void user_enter(void) { }
  41 static inline void user_exit(void) { }
  42 static inline void context_tracking_task_switch(struct task_struct *prev,
  43                                                 struct task_struct *next) { }
  44 #endif /* !CONFIG_CONTEXT_TRACKING */
  45
  46 #endif