Paper Info
Title
Low-Overhead Microarchitectural Patching for Multicore Memory Subsystems
Abstract
In this work, we present μMemPatch, a comprehensive, efficient patching solution to overcome escaped design flaws in multicore memory subsystems at runtime. Unlike conventional microcode patching, μMemPatch strives to accurately pinpoint bug-prone microarchitectural states at runtime, by using a small programmable-logic fabric. μMemPatch comprises two main components: a bug-anticipation module and a bug-elusion module. The bug-anticipation module tracks, at runtime, the progress of microarchitectural events related to memory operations. Specifically, we model event sequences as finite state machines (FSM), where some of the FSM states represent bug-prone microarchitectural states. Upon detection of a bug-prone state, the bug-elusion module limits reorderings of instructions or memory accesses, so as to avoid falling into the bug state. We propose a few different bug-elusion methods, including squashing instructions, delaying cache evictions, and dynamically inserting fence operations. We implemented μMemPatch in a cycle-accurate full-system simulator. We then embedded eleven design bugs that span a wide range of bug types, which had been disclosed in product errata documents. Our evaluation with an in-house micro-benchmark suite and the SPLASH-2 suite shows that μMemPatch's bug-elusion methods successfully bypass all bugs at a performance impact of less than 1% on average (SPLASH-2). The area overhead in our setup is approximately 6% for an ARM Cortex-A9 core on average, over all bugs we considered.
Year
DOI
Venue
2018
10.1109/ICCD.2018.00014
2018 IEEE 36th International Conference on Computer Design (ICCD)
Keywords
Field
DocType
bug patching,runtime patching,memory bug classification,multicore,memory subsystem
Microcode,Suite,Computer science,Cache,Parallel computing,Finite-state machine,Multi-core processor
Conference
ISSN
ISBN
Citations 
1063-6404
978-1-5386-8478-8
0
PageRank 
References 
Authors
0.34
6
3
Name
Order
Citations
PageRank
Doo-Won Lee1454.38
Opeoluwa Matthews291.82
Valeria Bertacco3136586.93