In one embodiment, a processor comprises a programmable map and a circuit. The programmable map is configured to store data that identifies at least one instruction for which an architectural modification of an instruction set architecture implemented by the processor has been defined, wherein the processor does not implement the modification. The circuitry is configured to detect the instruction or its memory operands and cause a transition to Known Good Code (KGC), wherein the KGC is protected from unauthorized modification and is provided from an authenticated entity. The KGC comprises code that, when executed, emulates the modification. In another embodiment, an integrated circuit comprises at least one processor core; at least one other circuit; and a KGC source configured to supply KGC to the processor core for execution. The KGC comprises interface code for the other circuit whereby an application executing on the processor core interfaces to the other circuit through the KGC.