Providing Accountability in Heterogeneous Systems-on-Chip

When modern systems-on-chip (SoCs), containing designs from different organizations, miscompute or underperform in the field, discerning the responsible component is a non-trivial task. A perfectly accountable system is one in which the on-chip component at fault is always unambiguously detected. The achievement of accountability can be greatly aided by the collection of runtime information that captures the events in the system that led to the error. Such information collection must be fair and impartial to all parties. In this article, we prove that logging messages communicated between components from different organizations is sufficient to provide accountability, provided the logs are authentic. We then construct a solution based on this premise, with an on-chip trusted auditing system to authenticate the logs. We present a thorough design of the auditing system, and demonstrate that its performance overhead is a mere 0.49%, and its area overhead is a mere 0.194% (in a heterogeneous 48 core, 400mm2 chip). We also demonstrate the viability of this solution using three representative bugs found in popular commercial SoCs.