Implement dummy_id for NaCl architecture because we need to sandbox frame pointer.

gdb/nacl-tdep.c

Index: gdb/nacl-tdep.c
diff --git a/gdb/nacl-tdep.c b/gdb/nacl-tdep.c
index 9a408ddbfcb534f2b1a730b980c86be6daf521b3..f33af438dcbbac6701553a6b09c5d2754c47e16a 100644
--- a/gdb/nacl-tdep.c
+++ b/gdb/nacl-tdep.c
@@ -162,6 +162,17 @@ amd64_nacl_software_single_step (struct frame_info *frame)
   return 0;
 }
 
+static struct frame_id
+amd64_nacl_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame)
+{
+  CORE_ADDR fp;
+
+  fp = get_frame_register_unsigned (this_frame, AMD64_RBP_REGNUM) + 16;
+  fp = amd64_nacl_addr_bits_remove(gdbarch, fp);
+
+  return frame_id_build (fp, get_frame_pc (this_frame));
+}
+
 static void
 amd64_nacl_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 {
@@ -199,6 +210,8 @@ amd64_nacl_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
   set_gdbarch_adjust_breakpoint_address (gdbarch,
                                          amd64_nacl_adjust_breakpoint_address);
   set_gdbarch_software_single_step (gdbarch, amd64_nacl_software_single_step);
+  /* Recognizing dummy frames.  */
+  set_gdbarch_dummy_id(gdbarch, amd64_nacl_dummy_id);
 }
 
 /* Provide a prototype to silence -Wmissing-prototypes.  */