Index: mm/arch/i386/kernel/traps.c
===================================================================
--- mm.orig/arch/i386/kernel/traps.c	2005-09-03 11:22:39.000000000 +0200
+++ mm/arch/i386/kernel/traps.c	2005-09-03 18:17:00.000000000 +0200
@@ -148,6 +148,48 @@
 		p < (void *)tinfo + THREAD_SIZE - 3;
 }
 
+unsigned long *next_stack_func(unsigned long *prev_addr, int count)
+{
+	struct thread_info *tinfo = current_thread_info();
+
+	if (!prev_addr)
+		return NULL;
+
+#ifdef CONFIG_FRAME_POINTER
+	/* In this case 'prev_addr' is a pointer to the last return
+	 * function found on the stack */
+	if (count == 0) {
+		unsigned long ebp;
+		unsigned long *func_ptr;
+
+		asm ("movl %%ebp, %0" : "=r" (ebp) : );
+		/* We don't want the obvious caller to show up */
+		ebp = *(unsigned long *) ebp;
+		func_ptr = (unsigned long *)(ebp + 4);
+		if (valid_stack_ptr(tinfo, func_ptr))
+			return func_ptr;
+	} else {
+		unsigned long *func_ptr;
+		unsigned long ebp = (unsigned long) prev_addr;
+
+		ebp -= 4;
+
+		ebp = *(unsigned long *) ebp;
+		func_ptr = (unsigned long *) ((unsigned long)ebp + 4);
+		if (valid_stack_ptr(tinfo, func_ptr))
+			return func_ptr;
+	}
+#else
+	while (prev_addr++) {
+		if (!valid_stack_ptr(tinfo, prev_addr))
+			break;
+		if (__kernel_text_address(*prev_addr))
+			return prev_addr;
+	}
+#endif
+	return NULL;
+}
+
 static inline unsigned long print_context_stack(struct thread_info *tinfo,
 				unsigned long *stack, unsigned long ebp)
 {
Index: mm/include/linux/sched.h
===================================================================
--- mm.orig/include/linux/sched.h	2005-09-03 11:22:51.000000000 +0200
+++ mm/include/linux/sched.h	2005-09-03 15:52:20.000000000 +0200
@@ -171,6 +171,7 @@
  * trace (or NULL if the entire call-chain of the task should be shown).
  */
 extern void show_stack(struct task_struct *task, unsigned long *sp);
+extern unsigned long *next_stack_func(unsigned long *prev_addr, int count);
 
 void io_schedule(void);
 long io_schedule_timeout(long timeout);
Index: mm/arch/x86_64/kernel/traps.c
===================================================================
--- mm.orig/arch/x86_64/kernel/traps.c	2005-09-03 17:59:16.000000000 +0200
+++ mm/arch/x86_64/kernel/traps.c	2005-09-03 19:00:48.000000000 +0200
@@ -154,6 +154,54 @@
 	return NULL;
 }
 
+static inline int valid_stack_ptr(struct thread_info *tinfo, void *p)
+{
+	return	p > (void *)tinfo &&
+		p < (void *)tinfo + THREAD_SIZE - 3;
+}
+
+unsigned long *next_stack_func(unsigned long *prev_addr, int count)
+{
+	struct thread_info *tinfo = current_thread_info();
+
+	if (!prev_addr)
+		return NULL;
+
+#ifdef CONFIG_FRAME_POINTER
+	/* In this case 'prev_addr' is a pointer to the last return
+	 * function found on the stack */
+	if (count == 0) {
+		unsigned long rbp;
+		unsigned long *func_ptr;
+
+		asm ("movq %%rbp, %0" : "=r" (rbp) : );
+		/* We don't want the obvious caller to show up */
+		rbp = *(unsigned long *) rbp;
+		func_ptr = (unsigned long *)(rbp + 8);
+		if (valid_stack_ptr(tinfo, func_ptr))
+			return func_ptr;
+	} else {
+		unsigned long *func_ptr;
+		unsigned long rbp = (unsigned long) prev_addr;
+
+		rbp -= 8;
+
+		rbp = *(unsigned long *) rbp;
+		func_ptr = (unsigned long *) ((unsigned long)rbp + 8);
+		if (valid_stack_ptr(tinfo, func_ptr))
+			return func_ptr;
+	}
+#else
+	while (prev_addr++) {
+		if (!valid_stack_ptr(tinfo, prev_addr))
+			break;
+		if (__kernel_text_address(*prev_addr))
+			return prev_addr;
+	}
+#endif
+	return NULL;
+}
+
 /*
  * x86-64 can have upto three kernel stacks: 
  * process stack