1 files changed, 22 insertions, 0 deletions

diff --git a/arch/sh/kernel/dwarf.c b/arch/sh/kernel/dwarf.c
index 03b3616c80a5..2d07084e4882 100644
--- a/arch/sh/kernel/dwarf.c
+++ b/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");