Fine Grained Control Flow Checking with Dedicated FPGA Monitors

Abstract

Control flow errors are known to compose the most common type of error for embedded systems in safety-critical environments. While data protection techniques can be easily implemented with special codifications, control flow monitoring techniques either require significant hardware modifications or impose prohibitive software overheads. We propose a new control flow trace checker (CFTC) scheme which can achieve high detection rates without modifying processor hardware or adding execution overheads. Our technique can detect 97.8% of all single bit flips to control flow operations, with detection delays as fast as 0.6 µs on a Cortex-A9 CPU.