Research On Type Analysis In Decompilation For Arm Architecture

The embedded systems with ARM micro processor core are widely used in pivotal electronic equipments of defense, communications, etc. It's important to analyze the structure and function of its code by using the technology of reverse engineering. One of the key steps in code decompilation is type analysis.In this thesis, based on analyzing the semantic information of ARM assembly instructions, the extraction rules of type feature which have been combined with the definition of type variable are summed up; In view of the characteristics of intermediate language(IL),the method of generating type attributes of the IL statements is designed, the different operators in the expression of the IL statements are highlighted, and the type attributes are added to the IL which is primitive and unincorporated type information; By using the type attributes of the IL, the way of propagation which is based on bidirectional data flow analysis is proposed, so that the problem of obtaining more accurate type information is solved; The reconstruction methods of array and structure type are designed. The course of design is related to the analysis of the relationship between memory access expressions; The implementation of a prototype of type analysis in decompilation for ARM is also mentioned in this thesis.The correctness of the type analysis methods of the basic and complex type is validated by testing abundant instances. According to the results, the discussion of the type analysis in this thesis is comprehensive, implemented easily, and with better practicality and expandability.