Novel Control Flow Checking Implementations for Automotive Software

Safety-critical applications shall be implemented on highly dependable systems, and a part of their reliability is based on checking if the software is executed correctly. Various techniques are available for this purpose, like Control Flow Checking (CFC). Many CFC algorithms can be found in the literature, but their detection performances are assessed in theoretical scenarios, when implemented in Assembly language. The international standard on functional safety for automotive applications is ISO26262. It mandates to develop using high-level programming languages and the computation of the Diagnostic Coverage (DC). The DC measures the effectiveness of the chosen hardening method, in order to detect various Failure Modes (FMs). This paper discusses two alternative solutions, one software-only, and the other involving customized hardware, for these concerns: (i) address the FMs affecting the computation units described by Table 30 of part 11 of the ISO26262 (ii) guarantee the Freedom From Interference between the hardening method and the monitored entity.