Method and system for on demand control of hardware support for software pointer authentification in a computing system

A computer system, processor, computer program product, and method for executing instructions in a software application that includes a processor that can be dynamically controlled, in response to a value set in a control register, to operate in either a secure mode or a performance mode. In the secure mode, the processor: upon encountering a secure mode entry instruction, computes an entry hash value using a hash function and stores the entry hash value; and upon encountering a secure mode exit instruction, computes an exit hash value, loads the entry hash value, and determines whether the entry hash value is the same as the exit hash value, and depending upon verification of the hash values can execute the return function or transfer control to the operating system. In the performance mode, the processor: executes both the secure mode entry instruction and the secure mode exit instruction as no-operations.