Fault localization in embedded software based on a single cyclic trace

Locating faults in embedded software, especially in microcontrollers, is still difficult. Quite recently, it became possible to recover execution traces from microcontrollers using specific hardware probes. However, the collected traces contain a huge volume of low-level data. Consequently, manual analysis is difficult and our industrial partners call for automatic and more effective fault-localization methods for embedded software. This paper presents a new approach to automatically locate faults in embedded programs given a single faulty execution trace. Our approach exploits the cyclic nature of embedded programs and uses several adapted spectrum-based methods in order to find faults on a single execution, rather than a set of multiple failing and passing executions. Our approach is implemented in the tool CoMET and evaluated on several faulty programs. The evaluation shows that our single-trace fault-localization method using Ochiai [1] allows engineers to find a fault by inspecting less than 5% of the program in most cases, and it confirms the interest of automatic fault localization for microcontrollers.