A practical verification framework for preemptive OS kernels

Abstract

We propose a practical verification framework for preemptive OS kernels. The framework models the correctness of API implementations in OS kernels as contextual refinement of their abstract specifications. It provides a specification language for defining the high-level abstract model of OS kernels, a program logic for refinement verification of concurrent kernel code with multi-level hardware interrupts, and automated tactics for developing mechanized proofs. The whole framework is developed for a practical subset of the C language. We have successfully applied it to verify key modules of a commercial preemptive OS μC/OS-II [2], including the scheduler, interrupt handlers, message queues, and mutexes etc. We also verify the priority-inversion-freedom (PIF) in μC/OS-II. All the proofs are mechanized in Coq. To our knowledge, our work is the first to verify the functional correctness of a practical preemptive OS kernel with machine-checkable proofs.