Design And Implementation Of Fault Injection Tool Target To CPU Based On JTAG

With rapid development of Internet and the mobile Internet, the application of computer systems gradually extended to the military, financial, telecommunications, aviation, aerospace, business management, education, energy and other sectors related to people's livelihood, more and more attention is paid to the reliability of computer systems. Fault injection method as a rapid, real-time, convenient method for reliability evaluation is widely used in reliability evaluation in fault tolerant computer research. Experiments show that using the tool, we can break the protect of operating system to make effective fault injection.Fault injection can be divided into different types according to different levels injection, software fault injection, software simulation of hardware fault injection, fault injection. When using traditional software fault injection and software of simulation hardware fault injection, due to the restrictions of the operating system protection mechanism, some faults that may appear in the bottom actually can not be injected. In view of this limitation, this paper designs and implements a hardware fault injection tool based on JTAG debugging.First of all, when the target system is in normal operation state, by setting breakpoints, setting watchpoints, sending request etc, to abort the current operation in the hardware level, and enter the hardware debugging mode. Secondly, through the bus-based scan chain shifting CPU instructions into the target system, and implementation of these instructions by single step in hardware debug mode, to modify the bus data, register data and memory data. Finally, by means of JTAG reset the target system returns to normal operating mode.In this process, bus data, register data,and memory data is changed. Due to operation of hardware debug mode exceeds the operating system protection, the operating system will not recognize that the data has been changed. After return to normal operation mode, the operating system will continue to perform the original task, thus fault injection makes effort. Experimental results show that useing of the fault injection tools break the operating system protection, make an effective fault injection.