1 files changed, 89 insertions, 96 deletions

diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
index d53cd331c4dd..af9fe87a0922 100644
--- a/include/linux/context_tracking.h
+++ b/include/linux/context_tracking.h
@@ -10,170 +10,163 @@
 #include <asm/ptrace.h>
 
 
-#ifdef CONFIG_CONTEXT_TRACKING
-extern void context_tracking_cpu_set(int cpu);
+#ifdef CONFIG_CONTEXT_TRACKING_USER
+extern void ct_cpu_track_user(int cpu);
 
 /* Called with interrupts disabled.  */
-extern void __context_tracking_enter(enum ctx_state state);
-extern void __context_tracking_exit(enum ctx_state state);
+extern void __ct_user_enter(enum ctx_state state);
+extern void __ct_user_exit(enum ctx_state state);
 
-extern void context_tracking_enter(enum ctx_state state);
-extern void context_tracking_exit(enum ctx_state state);
-extern void context_tracking_user_enter(void);
-extern void context_tracking_user_exit(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)
 {
 	if (context_tracking_enabled())
-		context_tracking_enter(CONTEXT_USER);
+		ct_user_enter(CT_STATE_USER);
 
 }
 static inline void user_exit(void)
 {
 	if (context_tracking_enabled())
-		context_tracking_exit(CONTEXT_USER);
+		ct_user_exit(CT_STATE_USER);
 }
 
 /* Called with interrupts disabled.  */
 static __always_inline void user_enter_irqoff(void)
 {
 	if (context_tracking_enabled())
-		__context_tracking_enter(CONTEXT_USER);
+		__ct_user_enter(CT_STATE_USER);
 
 }
 static __always_inline void user_exit_irqoff(void)
 {
 	if (context_tracking_enabled())
-		__context_tracking_exit(CONTEXT_USER);
+		__ct_user_exit(CT_STATE_USER);
 }
 
 static inline enum ctx_state exception_enter(void)
 {
 	enum ctx_state prev_ctx;
 
-	if (!context_tracking_enabled())
+	if (IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) ||
+	    !context_tracking_enabled())
 		return 0;
 
-	prev_ctx = this_cpu_read(context_tracking.state);
-	if (prev_ctx != CONTEXT_KERNEL)
-		context_tracking_exit(prev_ctx);
+	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 (context_tracking_enabled()) {
-		if (prev_ctx != CONTEXT_KERNEL)
-			context_tracking_enter(prev_ctx);
+	if (!IS_ENABLED(CONFIG_HAVE_CONTEXT_TRACKING_USER_OFFSTACK) &&
+	    context_tracking_enabled()) {
+		if (prev_ctx != CT_STATE_KERNEL)
+			ct_user_enter(prev_ctx);
 	}
 }
 
+static __always_inline bool context_tracking_guest_enter(void)
+{
+	if (context_tracking_enabled())
+		__ct_user_enter(CT_STATE_GUEST);
 
-/**
- * ct_state() - return the current context tracking state if known
- *
- * Returns the current cpu's context tracking state if context tracking
- * is enabled.  If context tracking is disabled, returns
- * CONTEXT_DISABLED.  This should be used primarily for debugging.
- */
-static __always_inline enum ctx_state ct_state(void)
+	return context_tracking_enabled_this_cpu();
+}
+
+static __always_inline bool context_tracking_guest_exit(void)
 {
-	return context_tracking_enabled() ?
-		this_cpu_read(context_tracking.state) : CONTEXT_DISABLED;
+	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 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 enum ctx_state exception_enter(void) { return 0; }
+static inline int exception_enter(void) { return 0; }
 static inline void exception_exit(enum ctx_state prev_ctx) { }
-static inline enum ctx_state ct_state(void) { return CONTEXT_DISABLED; }
-#endif /* !CONFIG_CONTEXT_TRACKING */
-
-#define CT_WARN_ON(cond) WARN_ON(context_tracking_enabled() && (cond))
-
-#ifdef CONFIG_CONTEXT_TRACKING_FORCE
+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_FORCE */
+#endif /* CONFIG_CONTEXT_TRACKING_USER_FORCE */
 
+#ifdef CONFIG_CONTEXT_TRACKING_IDLE
+extern void ct_idle_enter(void);
+extern void ct_idle_exit(void);
 
-#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
-/* must be called with irqs disabled */
-static __always_inline void guest_enter_irqoff(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)
 {
-	instrumentation_begin();
-	if (vtime_accounting_enabled_this_cpu())
-		vtime_guest_enter(current);
-	else
-		current->flags |= PF_VCPU;
-	instrumentation_end();
-
-	if (context_tracking_enabled())
-		__context_tracking_enter(CONTEXT_GUEST);
-
-	/* KVM does not hold any references to rcu protected data when it
-	 * switches CPU into a guest mode. In fact switching to a guest mode
-	 * is very similar to exiting to userspace from rcu point of view. In
-	 * addition CPU may stay in a guest mode for quite a long time (up to
-	 * one time slice). Lets treat guest mode as quiescent state, just like
-	 * we do with user-mode execution.
-	 */
-	if (!context_tracking_enabled_this_cpu()) {
-		instrumentation_begin();
-		rcu_virt_note_context_switch(smp_processor_id());
-		instrumentation_end();
-	}
+	return raw_atomic_read(this_cpu_ptr(&context_tracking.state)) & CT_RCU_WATCHING;
 }
 
-static __always_inline void guest_exit_irqoff(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)
 {
-	if (context_tracking_enabled())
-		__context_tracking_exit(CONTEXT_GUEST);
-
-	instrumentation_begin();
-	if (vtime_accounting_enabled_this_cpu())
-		vtime_guest_exit(current);
-	else
-		current->flags &= ~PF_VCPU;
-	instrumentation_end();
+	return raw_atomic_add_return(incby, this_cpu_ptr(&context_tracking.state));
 }
 
-#else
-static __always_inline void guest_enter_irqoff(void)
+static __always_inline bool warn_rcu_enter(void)
 {
+	bool ret = false;
+
 	/*
-	 * This is running in ioctl context so its safe
-	 * to assume that it's the stime pending cputime
-	 * to flush.
+	 * Horrible hack to shut up recursive RCU isn't watching fail since
+	 * lots of the actual reporting also relies on RCU.
 	 */
-	instrumentation_begin();
-	vtime_account_kernel(current);
-	current->flags |= PF_VCPU;
-	rcu_virt_note_context_switch(smp_processor_id());
-	instrumentation_end();
+	preempt_disable_notrace();
+	if (!rcu_is_watching_curr_cpu()) {
+		ret = true;
+		ct_state_inc(CT_RCU_WATCHING);
+	}
+
+	return ret;
 }
 
-static __always_inline void guest_exit_irqoff(void)
+static __always_inline void warn_rcu_exit(bool rcu)
 {
-	instrumentation_begin();
-	/* Flush the guest cputime we spent on the guest */
-	vtime_account_kernel(current);
-	current->flags &= ~PF_VCPU;
-	instrumentation_end();
+	if (rcu)
+		ct_state_inc(CT_RCU_WATCHING);
+	preempt_enable_notrace();
 }
-#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
 
-static inline void guest_exit(void)
-{
-	unsigned long flags;
+#else
+static inline void ct_idle_enter(void) { }
+static inline void ct_idle_exit(void) { }
 
-	local_irq_save(flags);
-	guest_exit_irqoff();
-	local_irq_restore(flags);
-}
+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