1 files changed, 47 insertions, 0 deletions
diff --git a/kernel/include/linux/context_tracking_state.h b/kernel/include/linux/context_tracking_state.h
new file mode 100644
index 000000000..6b7b96a32
--- /dev/null
+++ b/kernel/include/linux/context_tracking_state.h
@@ -0,0 +1,47 @@
+#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 {
+		CONTEXT_KERNEL = 0,
+		CONTEXT_USER,
+		CONTEXT_GUEST,
+	} 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_is_enabled(void)
+{
+	return static_key_false(&context_tracking_enabled);
+}
+
+static inline bool context_tracking_cpu_is_enabled(void)
+{
+	return __this_cpu_read(context_tracking.active);
+}
+
+static inline bool context_tracking_in_user(void)
+{
+	return __this_cpu_read(context_tracking.state) == CONTEXT_USER;
+}
+#else
+static inline bool context_tracking_in_user(void) { return false; }
+static inline bool context_tracking_active(void) { return false; }
+static inline bool context_tracking_is_enabled(void) { return false; }
+static inline bool context_tracking_cpu_is_enabled(void) { return false; }
+#endif /* CONFIG_CONTEXT_TRACKING */
+
+#endif