Low-cost control flow error protection by exploiting available redundancies in the pipeline

Due to device miniaturization and reducing supply voltage, embedded systems are becoming more susceptible to transient faults. Specifically, faults in control flow can change the execution sequence, which might be catastrophic for safety critical applications. Many techniques are devised using software, hardware or software-hardware co-design for control flow error checking. Software techniques suffer from a significant amount of code size overhead, and hence, negative impact on performance and energy consumption. On the other hand, hardware-based techniques have a significant amount of hardware and area cost. In this research we exploit the available redundancies in the pipeline. The branch target buffer stores target addresses of taken branches, and ALU generates target addresses using the low-order branch displacement bits of branch instructions. To exploit these redundancies in the pipeline, we propose a control flow error checking (CFEC) scheme. It can detect control flow errors and recover from them with negligible energy and performance overhead.