From 837a3d84d04bc46261ea2cf22eb06fe48968ce42 Mon Sep 17 00:00:00 2001
From: Matt Fleming <matt@console-pimps.org>
Date: Sat, 24 Oct 2009 18:56:57 +0000
Subject: [PATCH] --- yaml --- r: 167893 b: refs/heads/master c:
 60339fad5c68c9c533cd14e67194ff8f727c41d9 h: refs/heads/master i:   167891:
 d0abd173130686f5989ef6810dc3dbe2ffb738c2 v: v3

---
 [refs]                       |  2 +-
 trunk/arch/sh/kernel/dwarf.c | 22 ++++++++++++++++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 66f75df11490..5d9574d8bac2 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 26fadd3672964596d33548490b9756014ae0f414
+refs/heads/master: 60339fad5c68c9c533cd14e67194ff8f727c41d9
diff --git a/trunk/arch/sh/kernel/dwarf.c b/trunk/arch/sh/kernel/dwarf.c
index 03b3616c80a5..2d07084e4882 100644
--- a/trunk/arch/sh/kernel/dwarf.c
+++ b/trunk/arch/sh/kernel/dwarf.c
@@ -20,6 +20,7 @@
 #include <linux/list.h>
 #include <linux/mempool.h>
 #include <linux/mm.h>
+#include <linux/ftrace.h>
 #include <asm/dwarf.h>
 #include <asm/unwinder.h>
 #include <asm/sections.h>
@@ -557,6 +558,27 @@ struct dwarf_frame * dwarf_unwind_stack(unsigned long pc,
 	if (!pc && !prev)
 		pc = (unsigned long)current_text_addr();
 
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+	/*
+	 * If our stack has been patched by the function graph tracer
+	 * then we might see the address of return_to_handler() where we
+	 * expected to find the real return address.
+	 */
+	if (pc == (unsigned long)&return_to_handler) {
+		int index = current->curr_ret_stack;
+
+		/*
+		 * We currently have no way of tracking how many
+		 * return_to_handler()'s we've seen. If there is more
+		 * than one patched return address on our stack,
+		 * complain loudly.
+		 */
+		WARN_ON(index > 0);
+
+		pc = current->ret_stack[index].ret;
+	}
+#endif
+
 	frame = mempool_alloc(dwarf_frame_pool, GFP_ATOMIC);
 	if (!frame) {
 		printk(KERN_ERR "Unable to allocate a dwarf frame\n");