Low-Overhead Software Dynamic Translation

Software dynamic translation (SDT) is a technology that allows programs to be modified as they are running. The overhead of monitoring and modifying a running program’s instructions is often substantial in SDT. As a result SDT can be impractically slow, especially in SDT systems that do not or can not employ dynamic optimization to offset overhead. This is unfortunate since SDT has obvious advantages in modern computing environments and interesting applications of SDT continue to emerge. In this paper we introduce two novel overhead reduction techniques that can improve SDT performance by a factor of three even when no dynamic optimization is performed. To demonstrate the effectiveness of our overhead reduction techniques, and to show the type of useful tasks to which low-overhead, non-optimizing SDT systems might be put, we implemented two dynamic safety checkers with SDT. These dynamic safety checkers perform useful tasks–preventing buffer-overrun exploits and restricting system call usage in untrusted binaries. Further their performance is similar to, and in some cases better than, state-of-the-art tools that perform the same functions without SDT.