text: #ifndef _LINUX_CONTEXT_TRACKING_STATE_H
  #define _LINUX_CONTEXT_TRACKING_STATE_H
  
  #include <linux/percpu.h>
  #include <linux/static_key.h>
  
  struct context_tracking {
  	/*
  	 * When active is false, probes are unset in order
  	 * to minimize overhead: TIF flags are cleared
  	 * and calls to user_enter/exit are ignored. This
  	 * may be further optimized using static keys.
  	 */
  	bool active;
  	enum ctx_state {
  		IN_KERNEL = 0,
  		IN_USER,
  	} state;
  };
  
  #ifdef CONFIG_CONTEXT_TRACKING
  extern struct static_key context_tracking_enabled;
  DECLARE_PER_CPU(struct context_tracking, context_tracking);
  
  static inline bool context_tracking_in_user(void)
  {
  	return __this_cpu_read(context_tracking.state) == IN_USER;
  }
  
  static inline bool context_tracking_active(void)
  {
  	return __this_cpu_read(context_tracking.active);
  }
  #else
  static inline bool context_tracking_in_user(void) { return false; }
  static inline bool context_tracking_active(void) { return false; }
  #endif /* CONFIG_CONTEXT_TRACKING */
  
  #endif
  