Bringing Worst Case Execution Time Awareness to an Open Smart Card OS

Smart card platforms are migrating from restrictive proprietary environments to open multi-application infrastructures. Computing the worst case execution time of an embedded application while there is no way to make previous assumptions on the CPU configuration available on the smart card had to be faced differently. In this paper, an evaluation of a distributed WCET computation method is presented. A low-level analysis on an ARM7TDMI CPU core is also described. We explain how the global WCET of a dynamically loaded application is extracted. Experimental results show a small overestimation compared to the observed execution time for a PIN-based authentication applet. Hardware-dependent WCET computation can also take advantage of the typing information related to the intermediate language. Improvement in the performance evaluation is up to 81,22%.