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                 IN_KERNEL = 0,
  17                 IN_USER,
  18         } state;
  19 };
  20
  21 #ifdef CONFIG_CONTEXT_TRACKING
  22 extern struct static_key context_tracking_enabled;
  23 DECLARE_PER_CPU(struct context_tracking, context_tracking);
  24
  25 static inline bool context_tracking_is_enabled(void)
  26 {
  27         return static_key_false(&context_tracking_enabled);
  28 }
  29
  30 static inline bool context_tracking_cpu_is_enabled(void)
  31 {
  32         return __this_cpu_read(context_tracking.active);
  33 }
  34
  35 static inline bool context_tracking_in_user(void)
  36 {
  37         return __this_cpu_read(context_tracking.state) == IN_USER;
  38 }
  39 #else
  40 static inline bool context_tracking_in_user(void) { return false; }
  41 static inline bool context_tracking_active(void) { return false; }
  42 #endif /* CONFIG_CONTEXT_TRACKING */
  43
  44 #endif