ARM: Do something predictable for an UNPREDICTABLE branch.

src/arch/arm/types.hh

@@ -333,6 +333,10 @@ namespace ArmISA
                     nextThumb(false);
                 } else {
                     warn("Bad interworking branch address %#x.\n", newPC);
+                    // This state is UNPREDICTABLE in the ARM architecture
+                    // The easy thing to do is just mask off the bit and
+                    // stay in the current mode, so we'll do that.
+                    newPC &= ~mask(2);
                 }
             }
             npc(newPC);