1. A method of storing computer instructions for execution, the method comprising: regulating a memory region for execute-only access; storing a set of instructions in the memory region; executing an early instruction among the set of instructions, wherein the executing the early instruction comprises loading a secret value into a volatile register, the volatile register configured in hardware to protect its contents in response to events that indicate activity by malicious or invalid code; and executing a set of subsequent instructions among the set of instructions, wherein a correct execution of the subsequent instructions depends on the secret value being loaded into the volatile register.