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         int recursion;
  16         enum ctx_state {
  17                 CONTEXT_DISABLED = -1,  /* returned by ct_state() if unknown */
  18                 CONTEXT_KERNEL = 0,
  19                 CONTEXT_USER,
  20                 CONTEXT_GUEST,
  21         } state;
  22 };
  23
  24 #ifdef CONFIG_CONTEXT_TRACKING
  25 extern struct static_key_false context_tracking_enabled;
  26 DECLARE_PER_CPU(struct context_tracking, context_tracking);
  27
  28 static inline bool context_tracking_is_enabled(void)
  29 {
  30         return static_branch_unlikely(&context_tracking_enabled);
  31 }
  32
  33 static inline bool context_tracking_cpu_is_enabled(void)
  34 {
  35         return __this_cpu_read(context_tracking.active);
  36 }
  37
  38 static inline bool context_tracking_in_user(void)
  39 {
  40         return __this_cpu_read(context_tracking.state) == CONTEXT_USER;
  41 }
  42 #else
  43 static inline bool context_tracking_in_user(void) { return false; }
  44 static inline bool context_tracking_active(void) { return false; }
  45 static inline bool context_tracking_is_enabled(void) { return false; }
  46 static inline bool context_tracking_cpu_is_enabled(void) { return false; }
  47 #endif /* CONFIG_CONTEXT_TRACKING */
  48
  49 #endif