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Deductive Binary Code Verification Against Source-Code-Level Specifications
There is a high demand in practical methods and tools to ensure total correctness of critical software components. A usual assumption is that the machine code (or binary code) generated by a compiler follows the semantics of the programming language. Unfortunately, modern compilers such as GCC and LLVM are too complex to be thoroughly verified, and bugs in the generated code are not uncommon. As an alternative approach, we suggest proving that the generated machine code still satisfies the functional properties expressed at the source code level. The suggested approach takes an ACSL-annotated C function along with its binary code and checks that the binary code meets the ACSL annotations. The main steps are as follows: (1) disassembling the machine code and extracting its semantics; (2) adapting the annotations to the machine level and generating the verification conditions. The implementation utilizes MicroTESK, Frama-C, Why3, and other tools. To illustrate the solution, we use the RISC-V microprocessor architecture; however, the approach is relatively independent of the target platform as it is based on formal specifications of the instruction set. It is worth noting that the presented method can be exploited as a test oracle for compiler testing.