FT-PIP: Flush Task Incorporated Priority-Inheritance Protocol to Reduce Information Leakage on Multiprocessor Real-Time Systems

In a traditional real-time system, the major requirement is to finish every real-time task within its predefined time. However, as a modern real-time system is connected to external networks and its subsystems are developed by different vendors, it becomes an important requirement to address the problem of information leakage on resources shared by different real-time tasks. This triggers studies that incorporate security mechanisms into the real-time scheduling. While it is one of the most well-known approaches to add the flush task (FT) mechanism and analyze its effect on timing guarantees, the existing FT approaches have been limited to a real-time system that employs at most one resource shared by real-time tasks executed on a uniprocessor platform. In this paper, we propose a flush task incorporated priority-inheritance protocol (FT-PIP) for global fixed-priority multiprocessor scheduling and develop its schedulability analysis, which is the first attempt that not only (a) supports timing guarantees but also (b) satisfies security constraints for (c) a multiprocessor platform with multiple shared resources. Via simulations, we demonstrate that FT-PIP and its schedulability analysis are effective in achieving both (a) and (b) for (c).