UFO: A General-Purpose User-Mode Memory Protection Technique for Application Use

Neelakantam, Naveen; Zilles, Craig

Permalink

https://hdl.handle.net/2142/11287 Copy

Description

Title

UFO: A General-Purpose User-Mode Memory Protection Technique for Application Use

Author(s)

• Neelakantam, Naveen
• Zilles, Craig

Issue Date

2007-01

Keyword(s)

computer science

Abstract

In this paper, we advocate for a general-purpose, fine-grain memory protection mechanism for use by applications and software development tools. The hardware component of this mechanism consists of two bits (fault-on-read and fault-on-write) that are associated with each cache block and transferred with the block by the cache coherence system. When an access is performed that violates the protection on the block, a user handler is called, which can perform an arbitrary software-defined action. We describe a complete implementation that handles real world issues like protecting arbitrarily large regions, context switches, swapping, and multiprocessing. We demonstrate three examples of this mechanism in applications: 1) to detect self-modifying code (SMC) in a dynamic translator, 2) to detect common memory-related software bugs, and 3) to guard mostly-invariant heap variables in order to enable speculative optimizations. Because checking for conflicts does not directly impact performance, we find our mechanism has run-time overhead that is either negligible or at least comparable to special-purpose hardware for the same application. Furthermore, by virtue of providing a software interface to use the fine-grain protection mechanism, we can support multiple uses of the protection mechanism within the same application, enabling arbitrary composition of tools and libraries which use it.

Type of Resource

text

Permalink

http://hdl.handle.net/2142/11287

Copyright and License Information

You are granted permission for the non-commercial reproduction, distribution, display, and performance of this technical report in any format, BUT this permission is only for a period of 45 (forty-five) days from the most recent time that you verified that this technical report is still available from the University of Illinois at Urbana-Champaign Computer Science Department under terms that include this permission. All other rights are reserved by the author(s).

Owning Collections