Fast and low-cost instruction-aware fault injection

Abstract

In order to assess the robustness of software-based fault-tolerance methods, extensive tests have to be performed that inject faults, such as bit flips, into hardware components of a running system. Fault injection commonly uses either system simulations, resulting in execution times orders of magnitude longer than on real systems, or exposes a real system to error sources like radiation. This can take place in real time, but it enables only a very coarse-grained control over the affected system component. A solution combining the best characteristics from both approaches should achieve precise fault injection in real hardware systems. The approach presented in this paper uses the JTAG background debug facility of a CPU to inject faults into main memory and registers of a running system. Compared to similar earlier approaches, our solution is able to achieve rapid fault injection using a low-cost microcontroller instead of a complex FPGA. Consequently, our injection software is much more flexible. It allows to restrict error injection to the execution of a set of predefined components, resulting in a more precise control of the injection, and also emulates error reporting, which enables the evaluation of different error detection approaches in addition to robustness evaluation.