1 files changed, 131 insertions, 60 deletions

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index fc09d7b0dacf..af9fe87a0922 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -1,101 +1,172 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 #ifndef _LINUX_CONTEXT_TRACKING_H
 #define _LINUX_CONTEXT_TRACKING_H
 
 #include <linux/sched.h>
-#include <linux/percpu.h>
 #include <linux/vtime.h>
+#include <linux/context_tracking_state.h>
+#include <linux/instrumentation.h>
+
 #include <asm/ptrace.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;
-};
-
-static inline void __guest_enter(void)
-{
-	/*
-	 * This is running in ioctl context so we can avoid
-	 * the call to vtime_account() with its unnecessary idle check.
-	 */
-	vtime_account_system(current);
-	current->flags |= PF_VCPU;
-}
 
-static inline void __guest_exit(void)
-{
-	/*
-	 * This is running in ioctl context so we can avoid
-	 * the call to vtime_account() with its unnecessary idle check.
-	 */
-	vtime_account_system(current);
-	current->flags &= ~PF_VCPU;
-}
+#ifdef CONFIG_CONTEXT_TRACKING_USER
+extern void ct_cpu_track_user(int cpu);
 
-#ifdef CONFIG_CONTEXT_TRACKING
-DECLARE_PER_CPU(struct context_tracking, context_tracking);
+/* Called with interrupts disabled.  */
+extern void __ct_user_enter(enum ctx_state state);
+extern void __ct_user_exit(enum ctx_state state);
 
-static inline bool context_tracking_in_user(void)
+extern void ct_user_enter(enum ctx_state state);
+extern void ct_user_exit(enum ctx_state state);
+
+extern void user_enter_callable(void);
+extern void user_exit_callable(void);
+
+static inline void user_enter(void)
 {
-	return __this_cpu_read(context_tracking.state) == IN_USER;
-}
+	if (context_tracking_enabled())
+		ct_user_enter(CT_STATE_USER);
 
-static inline bool context_tracking_active(void)
+}
+static inline void user_exit(void)
 {
-	return __this_cpu_read(context_tracking.active);
+	if (context_tracking_enabled())
+		ct_user_exit(CT_STATE_USER);
 }
 
-extern void user_enter(void);
-extern void user_exit(void);
+/* Called with interrupts disabled.  */
+static __always_inline void user_enter_irqoff(void)
+{
+	if (context_tracking_enabled())
+		__ct_user_enter(CT_STATE_USER);
 
-extern void guest_enter(void);
-extern void guest_exit(void);
+}
+static __always_inline void user_exit_irqoff(void)
+{
+	if (context_tracking_enabled())
+		__ct_user_exit(CT_STATE_USER);
+}
 
 static inline enum ctx_state exception_enter(void)
 {
 	enum ctx_state prev_ctx;
 
-	prev_ctx = this_cpu_read(context_tracking.state);
-	user_exit();
+	if (IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) ||
+	    !context_tracking_enabled())
+		return 0;
+
+	prev_ctx = __ct_state();
+	if (prev_ctx != CT_STATE_KERNEL)
+		ct_user_exit(prev_ctx);
 
 	return prev_ctx;
 }
 
 static inline void exception_exit(enum ctx_state prev_ctx)
 {
-	if (prev_ctx == IN_USER)
-		user_enter();
+	if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) &&
+	    context_tracking_enabled()) {
+		if (prev_ctx != CT_STATE_KERNEL)
+			ct_user_enter(prev_ctx);
+	}
 }
 
-extern void context_tracking_task_switch(struct task_struct *prev,
-					 struct task_struct *next);
+static __always_inline bool context_tracking_guest_enter(void)
+{
+	if (context_tracking_enabled())
+		__ct_user_enter(CT_STATE_GUEST);
+
+	return context_tracking_enabled_this_cpu();
+}
+
+static __always_inline bool context_tracking_guest_exit(void)
+{
+	if (context_tracking_enabled())
+		__ct_user_exit(CT_STATE_GUEST);
+
+	return context_tracking_enabled_this_cpu();
+}
+
+#define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
+
 #else
-static inline bool context_tracking_in_user(void) { return false; }
 static inline void user_enter(void) { }
 static inline void user_exit(void) { }
+static inline void user_enter_irqoff(void) { }
+static inline void user_exit_irqoff(void) { }
+static inline int exception_enter(void) { return 0; }
+static inline void exception_exit(enum ctx_state prev_ctx) { }
+static inline int ct_state(void) { return -1; }
+static inline int __ct_state(void) { return -1; }
+static __always_inline bool context_tracking_guest_enter(void) { return false; }
+static __always_inline bool context_tracking_guest_exit(void) { return false; }
+#define CT_WARN_ON(cond) do { } while (0)
+#endif /* !CONFIG_CONTEXT_TRACKING_USER */
+
+#ifdef CONFIG_CONTEXT_TRACKING_USER_FORCE
+extern void context_tracking_init(void);
+#else
+static inline void context_tracking_init(void) { }
+#endif /* CONFIG_CONTEXT_TRACKING_USER_FORCE */
+
+#ifdef CONFIG_CONTEXT_TRACKING_IDLE
+extern void ct_idle_enter(void);
+extern void ct_idle_exit(void);
+
+/*
+ * Is RCU watching the current CPU (IOW, it is not in an extended quiescent state)?
+ *
+ * Note that this returns the actual boolean data (watching / not watching),
+ * whereas ct_rcu_watching() returns the RCU_WATCHING subvariable of
+ * context_tracking.state.
+ *
+ * No ordering, as we are sampling CPU-local information.
+ */
+static __always_inline bool rcu_is_watching_curr_cpu(void)
+{
+	return raw_atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_RCU_WATCHING;
+}
 
-static inline void guest_enter(void)
+/*
+ * Increment the current CPU's context_tracking structure's ->state field
+ * with ordering.  Return the new value.
+ */
+static __always_inline unsigned long ct_state_inc(int incby)
 {
-	__guest_enter();
+	return raw_atomic_add_return(incby, this_cpu_ptr(&context_tracking.state));
 }
 
-static inline void guest_exit(void)
+static __always_inline bool warn_rcu_enter(void)
 {
-	__guest_exit();
+	bool ret = false;
+
+	/*
+	 * Horrible hack to shut up recursive RCU isn't watching fail since
+	 * lots of the actual reporting also relies on RCU.
+	 */
+	preempt_disable_notrace();
+	if (!rcu_is_watching_curr_cpu()) {
+		ret = true;
+		ct_state_inc(CT_RCU_WATCHING);
+	}
+
+	return ret;
 }
 
-static inline enum ctx_state exception_enter(void) { return 0; }
-static inline void exception_exit(enum ctx_state prev_ctx) { }
-static inline void context_tracking_task_switch(struct task_struct *prev,
-						struct task_struct *next) { }
-#endif /* !CONFIG_CONTEXT_TRACKING */
+static __always_inline void warn_rcu_exit(bool rcu)
+{
+	if (rcu)
+		ct_state_inc(CT_RCU_WATCHING);
+	preempt_enable_notrace();
+}
+
+#else
+static inline void ct_idle_enter(void) { }
+static inline void ct_idle_exit(void) { }
+
+static __always_inline bool warn_rcu_enter(void) { return false; }
+static __always_inline void warn_rcu_exit(bool rcu) { }
+#endif /* !CONFIG_CONTEXT_TRACKING_IDLE */
 
 #endif