Design Of Formal Verification Of The CSM In The XDSP

Digital signal processors are widely used in radar,sonar,digital communications,and voice and video signal processing.In order to ensure that the DSP can work normally and orderly,prevent certain access operations from causing errors in other programs and data,and prevent certain illegal access operations from damaging the storage space of the DSP,a memory protection function must be added to the DSP.To address the accessing security of the storage space in the xDSP,a code secure model was designed.The password matching flow was implanted by reading the password from the on-chip flash,and makes all zeros and all Fs judgments,and matches with the key register.Besides,a storage protection unit was designed by applying hardware protection principle which used to check whether the request of access the memory is secure or unsecure and to check whether the storage space in the xDSP was protected by CSM,to determine whether were allowed that unauthorized users accessed the protected memory,subsequently realized the data and program protection function of the storage space in xDSP.The assertion properties of the CSM and the storage protection unit were written by using the System Verilog Assertions.The functional verification of the CSM and storage protection unit based on the assertion verification method were completed.In the xDSP chip verification environment,the FPGA prototype verification method is used to complete the functional test of the CSM at power-on reset,protection state,unlock state and password matching failure in xDSP,and functional test of the storage protection unit at protection state(CSM=1)and unprotected state(CSM=0)in xDSP.The results showed that the CSM and the storage protection unit respectively implement the function of the password matching flow and the security attribute checking function of the accessing request when accessing the storage space.Thereby realized the protection function of the data and program in the storage space,prevented illegal programs from destroying the storage protection space and prevented unauthorized users to access the storage space.In addition,compared with the traditional simulation verification method,the assertion verification method effectively improved the code coverage,in which the code coverage of the CSM increased 10%or more under each function point test,and the assertion coverage and function coverage reached 100%,ensured the completeness of test verification.