The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 08, 1997
Filed:
Jan. 31, 1996
Barbara J Bryant, Clinton Corners, NY (US);
Glen E Garrison, Wallkill, NY (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A token controlled page protection technique for use in a virtual memory computer system (99). Generally, this technique assigns a unique token (440) to each program when that program requests a protected page of memory. The token is also assigned to the protected page. This protected page of memory cannot be altered by any process, even the operating system, without presenting the correct token. Subsequently, the program may use the assigned token to access and alter the information stored within a protected page. However, to alter a protected page of memory, a token supplied by the program and a token associated with the protected page must match. In this manner, the protected page cannot be altered by any other programs other than the program having the correct token. Additionally, the program uses a special instruction to alter the protected page of memory such that the program associated with a protected page does not have to remove the page protection to alter the information within the protected page. Consequently, the protected page is protected from inadvertent alteration by other programs even though the program using the special instruction and having the correct token can alter the contents of the page.