1. One or more computer-readable storage media comprising first instructions that, in response to execution by a computing device, cause the computing device to: determine that a second instruction to be executed on a computer processor of the computing device attempts to perform an access to a virtualized memory address location, the access to the virtualized memory address location being not permitted in accordance with a current virtualized-memory page table; and execute the second instruction on the computer processor in accordance with a substitute virtualized-memory page table, the substitute virtualized-memory page table configured to permit the access to the virtualized memory address location.