include/linux/context_tracking_state.h

   1 #ifndef _LINUX_CONTEXT_TRACKING_STATE_H
   2 #define _LINUX_CONTEXT_TRACKING_STATE_H
   3
   4 #include <linux/percpu.h>
   5 #include <linux/static_key.h>
   6
   7 struct context_tracking {
   8         /*
   9          * When active is false, probes are unset in order
  10          * to minimize overhead: TIF flags are cleared
  11          * and calls to user_enter/exit are ignored. This
  12          * may be further optimized using static keys.
  13          */
  14         bool active;
  15         enum ctx_state {
  16                 CONTEXT_KERNEL = 0,
  17                 CONTEXT_USER,
  18                 CONTEXT_GUEST,
  19         } state;
  20 };
  21
  22 #ifdef CONFIG_CONTEXT_TRACKING
  23 extern struct static_key context_tracking_enabled;
  24 DECLARE_PER_CPU(struct context_tracking, context_tracking);
  25
  26 static inline bool context_tracking_is_enabled(void)
  27 {
  28         return static_key_false(&context_tracking_enabled);
  29 }
  30
  31 static inline bool context_tracking_cpu_is_enabled(void)
  32 {
  33         return __this_cpu_read(context_tracking.active);
  34 }
  35
  36 static inline bool context_tracking_in_user(void)
  37 {
  38         return __this_cpu_read(context_tracking.state) == CONTEXT_USER;
  39 }
  40 #else
  41 static inline bool context_tracking_in_user(void) { return false; }
  42 static inline bool context_tracking_active(void) { return false; }
  43 static inline bool context_tracking_is_enabled(void) { return false; }
  44 static inline bool context_tracking_cpu_is_enabled(void) { return false; }
  45 #endif /* CONFIG_CONTEXT_TRACKING */
  46
  47 #endif