Gradual Software-Based Memory Protection

Software-based memory protection (MP) provides not only spatial isolation of different applications, but also additional means to detect programming errors within an application. However, this luxury comes at the cost of extra runtime checks that add overhead to the application. In this paper, we present the idea of gradual software-based MP, where we only add a subset of runtime checks to a program to gain configurability with respect to the tradeoff between dependability and cost. To support the selection, we analyze the importance of different classes of safety checks and research which types of checks could be implemented at no cost by a hardware protection unit. After examining the relative frequency of different runtime checks in a large Java class library, we expect these ideas to be applicable to the majority of runtime checks in an embedded application.