include/linux/context_tracking_state.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_CONTEXT_TRACKING_STATE_H
   3 #define _LINUX_CONTEXT_TRACKING_STATE_H
   4
   5 #include <linux/percpu.h>
   6 #include <linux/static_key.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         int recursion;
  17         enum ctx_state {
  18                 CONTEXT_DISABLED = -1,  /* returned by ct_state() if unknown */
  19                 CONTEXT_KERNEL = 0,
  20                 CONTEXT_USER,
  21                 CONTEXT_GUEST,
  22         } state;
  23 };
  24
  25 #ifdef CONFIG_CONTEXT_TRACKING
  26 extern struct static_key_false context_tracking_key;
  27 DECLARE_PER_CPU(struct context_tracking, context_tracking);
  28
  29 static __always_inline bool context_tracking_enabled(void)
  30 {
  31         return static_branch_unlikely(&context_tracking_key);
  32 }
  33
  34 static __always_inline bool context_tracking_enabled_cpu(int cpu)
  35 {
  36         return context_tracking_enabled() && per_cpu(context_tracking.active, cpu);
  37 }
  38
  39 static inline bool context_tracking_enabled_this_cpu(void)
  40 {
  41         return context_tracking_enabled() && __this_cpu_read(context_tracking.active);
  42 }
  43
  44 static __always_inline bool context_tracking_in_user(void)
  45 {
  46         return __this_cpu_read(context_tracking.state) == CONTEXT_USER;
  47 }
  48 #else
  49 static inline bool context_tracking_in_user(void) { return false; }
  50 static inline bool context_tracking_enabled(void) { return false; }
  51 static inline bool context_tracking_enabled_cpu(int cpu) { return false; }
  52 static inline bool context_tracking_enabled_this_cpu(void) { return false; }
  53 #endif /* CONFIG_CONTEXT_TRACKING */
  54
  55 #endif