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:
Dec. 14, 1999
Filed:
Nov. 17, 1997
Claude Moughanni, Austin, TX (US);
William C Moyer, Dripping Springs, TX (US);
Taimur Aslam, Austin, TX (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
A data processor (20) includes a firewall circuit (50) that monitors privilege level changes or transitions between privilege modes, such as from user mode and user space into supervisory or privileged mode and operating system space. The firewall circuit starts a timer (54) whenever a central processing unit (22) enters supervisor mode. If the timer (54) determines the passage of a predetermined time while the central processing unit remains continuously in supervisory mode without re-entering user mode, a predefined security policy is invoked. For example, the security policy may require at this point that the data processor (20) is to be reset. Different timer (54) time-out values and different security policies can be set for different types of privilege level changes. In one embodiment, a default time-out value provides protection for multiple types of privilege level changes.