gdb/
        * infrun.c (get_displaced_step_closure_by_addr): New.
        * inferior.h: Declare it.
        * arm-tdep.c: (arm_pc_is_thumb): Call
	get_displaced_step_closure_by_addr.  Adjust MEMADDR if it
	returns non-NULL.

diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index ef4d9f3..fb080c1 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -368,6 +368,20 @@ arm_pc_is_thumb (struct gdbarch *gdbarch, CORE_ADDR memaddr)
   struct obj_section *sec;
   struct minimal_symbol *sym;
   char type;
+  struct displaced_step_closure* dsc
+    = get_displaced_step_closure_by_addr(memaddr);
+
+  /* If checking the mode of displaced instruction in copy area, the mode
+     should be determined by instruction on the original address.  */
+  if (dsc)
+    {
+      if (debug_displaced)
+	fprintf_unfiltered (gdb_stdlog,
+			    "displaced: check mode of %.8lx instead of %.8lx\n",
+			    (unsigned long) dsc->insn_addr,
+			    (unsigned long) memaddr);
+      memaddr = dsc->insn_addr;
+    }
 
   /* If bit 0 of the address is set, assume this is a Thumb address.  */
   if (IS_THUMB_ADDR (memaddr))
diff --git a/gdb/inferior.h b/gdb/inferior.h
index 7052d6f..a319847 100644
--- a/gdb/inferior.h
+++ b/gdb/inferior.h
@@ -366,6 +366,8 @@ extern int debug_displaced;
 void displaced_step_dump_bytes (struct ui_file *file,
                                 const gdb_byte *buf, size_t len);
 
+struct displaced_step_closure*
+get_displaced_step_closure_by_addr (CORE_ADDR addr);
 
 /* Possible values for gdbarch_call_dummy_location.  */
 #define ON_STACK 1
diff --git a/gdb/infrun.c b/gdb/infrun.c
index dd6fe6c..0714308 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -1078,6 +1078,26 @@ add_displaced_stepping_state (int pid)
   return state;
 }
 
+/* If inferior is in displaced stepping, and ADDR equals to starting address
+   of copy area, return corresponding displaced_step_closure.  Otherwise,
+   return NULL.  */
+
+struct displaced_step_closure*
+get_displaced_step_closure_by_addr (CORE_ADDR addr)
+{
+  struct displaced_step_inferior_state *displaced
+    = get_displaced_stepping_state (ptid_get_pid (inferior_ptid));
+
+  /* If checking the mode of displaced instruction in copy area.  */
+  if (displaced && !ptid_equal (displaced->step_ptid, null_ptid)
+     && (displaced->step_copy == addr))
+    return displaced->step_closure;
+
+  return NULL;
+}
+
 /* Remove the displaced stepping state of process PID.  */
 
 static void