The increasing complexity of processors allied to the continuous technology shrink is making multicore-based systems more susceptible to soft errors. The high cost and time inherent to hardware-based fault injection approaches make the more efficient simulation-based fault injection frameworks crucial to test reliability. This paper proposes a fast, flexible fault injector framework which supports parallel instruction accurate simulation to boost up the fault injection process. Fault injection campaigns were performed on ARM processors, considering a Linux Kernel and benchmarks with up to 220 million object code instructions. Results have shown the injection of faults at speeds up to 1550 MIPS. This enables users to identify errors and exceptions according to different criteria and classifications.