Abstract: A system including storage comprising software code and a plurality of data structures. The system also includes processing logic coupled to the storage and adapted to execute the software code. If the processing logic executes a function call instruction, the processing logic stores copies of software code return information to a first data structure location and to a second data structure location. If, after executing a function associated with the function call instruction, the processing logic determines that data from the first and second data structure locations do not match, the processing logic initiates a security measure. The data is associated with the copies.