A Practical Methodology for the Formal Verification of RISC Processors

In this paper a practical methodology for formally verifying RISC cores is presented. This methodology is based on a hierarchical model of interpreters which reflects the abstraction levels used by a designer in the implementation of RISC cores, namely the architecture level, the pipeline stage level, the clock phase level and the hardware implementation. The use of this model allows us to successively prove the correctness between two neighbouring levels of abstractions, so that the verification process is simplified. The parallelism in the execution of the instructions, resulting from the pipelined architecture of RISCs is handled by splitting the proof into two independent steps. The first step shows that each architectural instruction is implemented correctly by the sequential execution of its pipeline stages. The second step shows that the instructions are correctly processed by the pipeline in that we prove that under certain constraints from the actual architecture, no conflic..