Software-based control flow error detection and correction using branch triplication

Ever Increasing use of commercial off-the-shelf (COTS) processors to reduce cost and time to market in embedded systems has brought significant challenges in error detection and recovery methods employing in such systems. This paper presents a software based control flow error detection and correction technique, so called branch TMR (BTMR), suitable for use in COTS-based embedded systems. In BTMR method, each branch instruction is triplicated and a software interrupt routine is invoked to check the correctness of the branch instruction. During the execution of a program, when a branch instruction is executed, it is compared with the second redundant branch in the interrupt routine. If a mismatch is detected, the third redundant branch instruction is considered as the error-free branch instruction; otherwise, no error has occurred. The main advantage of BTMR over previously proposed control flow checking (CFC) methods is its ability to correct CFEs as well as protection of indirect branch instructions. The BTMR method is evaluated on LEON2 embedded processor. The results show that, error correction coverage is about 96%, while memory overhead and performance overhead of BTMR is about 28% and 10%, respectively.