Selectable pointer validation in a computer system

Abstract

A computer system is described having selectable pointer validation. The pointer structure is modified to provide selectable pointer validation. Each pointer comprises an effective address portion and a validation enable field. The effective address portion defines the memory location referenced by the pointer. The validation enable field comprises one or more bits of information that indicate whether or not selectable pointer validation is enabled for the particular pointer. Prior to executing a pointer reference, a processor first loads the desired condition of the validation enable field of the pointer. In normal practice of the invention, a programmer would enable selective pointer validation for particular pointers under debug testing or pointers for which a problem may have been encountered. For those pointers for which selective pointer validation is disabled, the pointer reference to the specified effective address occurs without any pointer validation processing. If, however, selective pointer validation is enabled by setting the appropriate value in the validation enable field, additional processing steps are performed by the present invention in order to validate the access being made by the pointer. The pointer access is validated by comparing the effective address portion of the pointer with pointer access information maintained in a pointer descriptor table. The pointer descriptor table contains a pointer descriptor for each allocated pointer. The pointer descriptor for each allocated pointer comprises pointer access information including a base address, a limit address, and access privilege information or a protection value.