v4.19.13 snapshot.
diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h
new file mode 100644
index 0000000..d05609a
--- /dev/null
+++ b/include/linux/context_tracking.h
@@ -0,0 +1,175 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_CONTEXT_TRACKING_H
+#define _LINUX_CONTEXT_TRACKING_H
+
+#include <linux/sched.h>
+#include <linux/vtime.h>
+#include <linux/context_tracking_state.h>
+#include <asm/ptrace.h>
+
+
+#ifdef CONFIG_CONTEXT_TRACKING
+extern void context_tracking_cpu_set(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 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);
+
+static inline void user_enter(void)
+{
+ if (context_tracking_is_enabled())
+ context_tracking_enter(CONTEXT_USER);
+
+}
+static inline void user_exit(void)
+{
+ if (context_tracking_is_enabled())
+ context_tracking_exit(CONTEXT_USER);
+}
+
+/* Called with interrupts disabled. */
+static inline void user_enter_irqoff(void)
+{
+ if (context_tracking_is_enabled())
+ __context_tracking_enter(CONTEXT_USER);
+
+}
+static inline void user_exit_irqoff(void)
+{
+ if (context_tracking_is_enabled())
+ __context_tracking_exit(CONTEXT_USER);
+}
+
+static inline enum ctx_state exception_enter(void)
+{
+ enum ctx_state prev_ctx;
+
+ if (!context_tracking_is_enabled())
+ return 0;
+
+ prev_ctx = this_cpu_read(context_tracking.state);
+ if (prev_ctx != CONTEXT_KERNEL)
+ context_tracking_exit(prev_ctx);
+
+ return prev_ctx;
+}
+
+static inline void exception_exit(enum ctx_state prev_ctx)
+{
+ if (context_tracking_is_enabled()) {
+ if (prev_ctx != CONTEXT_KERNEL)
+ context_tracking_enter(prev_ctx);
+ }
+}
+
+
+/**
+ * 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 inline enum ctx_state ct_state(void)
+{
+ return context_tracking_is_enabled() ?
+ this_cpu_read(context_tracking.state) : CONTEXT_DISABLED;
+}
+#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 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_is_enabled() && (cond))
+
+#ifdef CONFIG_CONTEXT_TRACKING_FORCE
+extern void context_tracking_init(void);
+#else
+static inline void context_tracking_init(void) { }
+#endif /* CONFIG_CONTEXT_TRACKING_FORCE */
+
+
+#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
+/* must be called with irqs disabled */
+static inline void guest_enter_irqoff(void)
+{
+ if (vtime_accounting_cpu_enabled())
+ vtime_guest_enter(current);
+ else
+ current->flags |= PF_VCPU;
+
+ if (context_tracking_is_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_cpu_is_enabled())
+ rcu_virt_note_context_switch(smp_processor_id());
+}
+
+static inline void guest_exit_irqoff(void)
+{
+ if (context_tracking_is_enabled())
+ __context_tracking_exit(CONTEXT_GUEST);
+
+ if (vtime_accounting_cpu_enabled())
+ vtime_guest_exit(current);
+ else
+ current->flags &= ~PF_VCPU;
+}
+
+#else
+static inline void guest_enter_irqoff(void)
+{
+ /*
+ * This is running in ioctl context so its safe
+ * to assume that it's the stime pending cputime
+ * to flush.
+ */
+ vtime_account_system(current);
+ current->flags |= PF_VCPU;
+ rcu_virt_note_context_switch(smp_processor_id());
+}
+
+static inline void guest_exit_irqoff(void)
+{
+ /* Flush the guest cputime we spent on the guest */
+ vtime_account_system(current);
+ current->flags &= ~PF_VCPU;
+}
+#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
+
+static inline void guest_enter(void)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ guest_enter_irqoff();
+ local_irq_restore(flags);
+}
+
+static inline void guest_exit(void)
+{
+ unsigned long flags;
+
+ local_irq_save(flags);
+ guest_exit_irqoff();
+ local_irq_restore(flags);
+}
+
+#endif