Browse Prior Art Database

PSW KEY and PROGRAM PROTECTION FACILITY

IP.com Disclosure Number: IPCOM000041357D
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Butwell, JR: AUTHOR

Abstract

This article describes a special control which restricts the access capabilities of a program executing with a program-status-word (PSW) access key 0. The special control is implemented by a special control bit which is provided by the storage key (e.g., bit 7 in the storage key) and is referred to as the PSW KEY and PROGRAM PROTECTION FACILITY. Bit 7 of the storage key can be set to 0 or 1 by the instruction SET STORAGE KEY. When bit 7 is set to 1, a key match is needed for PSW access key 0 which makes a program executing with a PSW access key 0 behave as any other program access key. This special bit supports a class of operating systems (i.e., Multiple Virtual Storage) which supports access keys.

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PSW KEY and PROGRAM PROTECTION FACILITY

This article describes a special control which restricts the access capabilities of a program executing with a program-status-word (PSW) access key 0. The special control is implemented by a special control bit which is provided by the storage key (e.g., bit 7 in the storage key) and is referred to as the PSW KEY and PROGRAM PROTECTION FACILITY. Bit 7 of the storage key can be set to 0 or 1 by the instruction SET STORAGE KEY. When bit 7 is set to 1, a key match is needed for PSW access key 0 which makes a program executing with a PSW access key 0 behave as any other program access key. This special bit supports a class of operating systems (i.e., Multiple Virtual Storage) which supports access keys. Such an operating system can set the PSW KEY and PROGRAM PROTECTION FACILITY control bit to one and thus restrict the access authority of a program executing with a PSW access key 0 to access only key 0 storage.

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