Apparatus and method for controlling access to a memory unit

Electrical computers and digital processing systems: memory – Storage accessing and control – Control technique

Reexamination Certificate

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

C711S145000

Reexamination Certificate

active

07340573

ABSTRACT:
The present invention provides a data processing apparatus and method for controlling access to a memory unit. The data processing apparatus comprises a processor operable in a plurality of modes and a plurality of domains, said plurality of domains comprising a secure domain and a non-secure domain, said plurality of modes including at least one non-secure mode being a mode in the non-secure domain and at least one secure mode being a mode in the secure domain. The processor is operable such that when executing a program in a secure mode the program has access to secure data which is not accessible when the processor is operating in a non-secure mode. A memory unit is also provided that comprises a plurality of entries and is operable to store data required by the processor. Each entry is operable to store one or more data items consisting of either secure data or non-secure data, and a flag is associated with each entry in the memory unit to store a value indicating whether the one or more data items stored in the associated entry are secure data or non-secure data. When the processor is operating in the at least one non-secure mode, the memory unit is operable, upon receipt of a memory access request issued by the processor when access to an item of data is required, to prevent access to any data item within an entry of the memory unit that the associated flag indicates has secure data stored therein.

REFERENCES:
patent: 4521852 (1985-06-01), Guttag
patent: 4677546 (1987-06-01), Freeman et al.
patent: 4989178 (1991-01-01), Shonaka
patent: 5557771 (1996-09-01), Kawaguchi et al.
patent: 6282657 (2001-08-01), Kaplan et al.
patent: 6292874 (2001-09-01), Barnett
patent: 6397242 (2002-05-01), Devine et al.
patent: 2002/0007456 (2002-01-01), Peinado et al.
patent: 2003/0101322 (2003-05-01), Gardner
patent: 2004/0064351 (2004-04-01), Mikurak
patent: 0 288 606 (1973-07-01), None
patent: 0 614 159 (1994-09-01), None
patent: 62-28853 (1987-02-01), None
Microsoft Computer Dictionary, 5th edition, Microsoft Press © 2002, p. 81.
Trusted Computing Group (TCB), Main Specification Version 1.1a, Sep. 1, 2001, pp. i-x and 1-322.

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Apparatus and method for controlling access to a memory unit does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Apparatus and method for controlling access to a memory unit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus and method for controlling access to a memory unit will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-3974151

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.