Hardening an L4 microkernel against soft errors by aspect-oriented programming and whole-program analysis

Transient hardware faults in computer systems have become widespread as shrinking structures and low supply voltages reduce the amount of energy needed to trigger a fault. This paper describes the latest improvements of a software-based fault-tolerance mechanism called Generic Object Protection (GOP). It is based on Aspect-Orientied Programming in AspectC++ and has been used in a case study to harden the L4/Fiasco.OC microkernel. As a result, the improved GOP avoids 60% of kernel failures at an acceptable overhead of 19% code size and less than 1% runtime. The GOP improvements use static whole-program analysis and have been implemented in a prototypical manner. As an outlook, the paper presents envisioned language extensions providing whole-program control-flow and data-flow analyses in future AspectC++ versions.