操作系统汇编级形式化设计和验证方法

由于系统的巨大规模，操作系统设计和实现的正确性很难用传统的方法进行描述和验证.在汇编层形式化地对系统模块的功能语义进行建模，提出一种汇编级的系统状态模型，作为汇编语言层设计和验证的纽带.通过定义系统状态模型的合法状态和状态转换函数来建立系统状态模型的论域，并以此来描述汇编层的论域.通过验证汇编层的功能模块的正确性来保证汇编语言层设计的正确性，达到对系统功能实现的正确性验证.同时，使用定理证明工具Isabelle/HOL来形式化地描述这一系统状态模型，基于这一形式化模型，在Isabelle/HOL中验证系统模块的功能语义的正确性.以实现的安全可信OS（verified secure operating system，简称VSOS）为例，阐述了所提出的形式化设计和验证方法，说明了这一方法的可行性.

Method of Formal Design and Verification of OS on Assembly Layer

The correctness of design and implementation of operating system is difficult to be described and verified with the traditional methods, due to the huge size of the system. In this paper, a model is build for the functionality semantics of the system modules on the assembly layer. A system state model is proposed as the link of the design and verification on the assembly layer. Through defining the legal states and state transition functions, the universe of discourse of the system state model and the assembly layer are constructed. The correctness of functionality modules is verified to ensure the correctness of design and functionality implementation. Within the Isabelle/HOL theorem prover, the system state model is described, and the correctness of functionality semantics of the system modules is verified. Meanwhile, the self-implemented secure trusted operating system (verified secure operating system, VSOS) is used as the example to illustrate the proposed formal method for design and verification, and to show the feasibility of the method.