1. A data processing method comprising: receiving, at a first computer, relocation metadata comprising, for each particular execution unit among a plurality of execution units within an executable file comprising computer-executable instructions, a mapping of that particular execution unit from the executable file to an address space range; wherein the execution units are code functions or basic control blocks; for all execution units in the plurality of execution units, modifying the mapping to replace instructions within the address space range with a relocated copy of the instructions at a randomly located address space range based on using a randomization function that is unique to the first computer, and including modifying an order of the plurality of execution units; generating an image from the executable file using the relocation metadata; causing an execution of the image using a second computer; wherein the method is performed by one or more computing devices.