Apparatus and method for main memory unit protection using access and fault logic signals
AssigneeDigital Equipment Corporation
InventorsDavid N. Cutler, David A. Orbits, Dileep Bhandarkar, Wayne Cardoza, Richard T. Witek
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Abstract
In a data processing system, apparatus and method for controlling the type of processing to which data signal groups can be subjected includes a page table entry format having a multiplicity of field positions for storing signals defining page access rights. In addition to the read/write access control, the signal group access rights can be determined by the current mode of operation of the data processing unit and the intended activity of the addressed instruction or data element (i.e., read, write or execute).
Claims20
Apparatus for controlling access to and use of stored elements by a processor that requests said access by identifying one of said stored elements and indicating an indicated use for said one stored element from a set of uses, said apparatus comprising:
- a memory that includes a plurality of regions each of which stores multiple said stored elements,
- storage for a plurality of records each of which corresponds to one region of said plurality of regions and includes access information that defines uses in said set of uses for which said processor is permitted to access said one region and use information stored separately from said access information, said use information designating one or more uses for the multiple stored elements stored in said one region from said set of uses, and
- a controller for responding to one of said requests by:
- examining the access information in a corresponding record for a particular region in which the stored element identified in the request is stored and selectively granting said processor access to said particular region if said access information indicates that said processor is permitted to access said particular region for said indicated use, and
- if said access is granted, then examining the use information is said corresponding record and regulating use of said element by said processor based on said use information and said indicated use.
A method for controlling access to and use of stored elements by a processor of a kind that requests said access by identifying one of said stored elements and indicating an indicated use for said one stored element from a set of uses, said method comprising:
- providing a memory that includes a plurality of regions each of which stores multiple said stored elements,
- storing a plurality of records each of which corresponds to one region of said plurality of regions and includes access information that defines uses in said set of uses for which said processor is permitted to access said one region and use information stored separately from said access information, said use information designating one or more uses in said set of uses for the stored elements from said one region, and
- responding to one of said requests by:
- examining the access information in a corresponding record for a particular region in which the stored element identified in the request is stored and selectively granting said processor access to said particular region if said access information indicates that said processor is permitted to access said particular region for said indicated use, and
- if said processor is granted access, then examining the use information in said corresponding record and regulating use of said stored element by said processor based on said use information and said indicated use.
Dependencies are inferred from the claim text.