3 files changed, 32 insertions, 1 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 1f5608c1102..dcbbf72a88b 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -268,6 +268,26 @@ ftrace_init_module(unsigned long *start, unsigned long *end) { }
 
 
 /*
+ * Structure that defines a return function trace.
+ */
+struct ftrace_retfunc {
+	unsigned long ret; /* Return address */
+	unsigned long func; /* Current function */
+	unsigned long long calltime;
+	unsigned long long rettime;
+};
+
+#ifdef CONFIG_FUNCTION_RET_TRACER
+/* Type of a callback handler of tracing return function */
+typedef void (*trace_function_return_t)(struct ftrace_retfunc *);
+
+extern void register_ftrace_return(trace_function_return_t func);
+/* The current handler in use */
+extern trace_function_return_t ftrace_function_return;
+extern void unregister_ftrace_return(void);
+#endif
+
+/*
  * Structure which defines the trace of an initcall.
  * You don't have to fill the func field since it is
  * only used internally by the tracer.
diff --git a/include/linux/ftrace_irq.h b/include/linux/ftrace_irq.h
index b1299d6729f..0b4df55d7a7 100644
--- a/include/linux/ftrace_irq.h
+++ b/include/linux/ftrace_irq.h
@@ -2,7 +2,7 @@
 #define _LINUX_FTRACE_IRQ_H
 
 
-#ifdef CONFIG_DYNAMIC_FTRACE
+#if defined(CONFIG_DYNAMIC_FTRACE) || defined(CONFIG_FUNCTION_RET_TRACER)
 extern void ftrace_nmi_enter(void);
 extern void ftrace_nmi_exit(void);
 #else
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 295b7c756ca..df77abe860c 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2005,6 +2005,17 @@ static inline void setup_thread_stack(struct task_struct *p, struct task_struct
 {
 	*task_thread_info(p) = *task_thread_info(org);
 	task_thread_info(p)->task = p;
+
+#ifdef CONFIG_FUNCTION_RET_TRACER
+	/*
+	 * When fork() creates a child process, this function is called.
+	 * But the child task may not inherit the return adresses traced
+	 * by the return function tracer because it will directly execute
+	 * in userspace and will not return to kernel functions its parent
+	 * used.
+	 */
+	task_thread_info(p)->curr_ret_stack = -1;
+#endif
 }
 
 static inline unsigned long *end_of_stack(struct task_struct *p)