Incorporating Security Constraints into Mixed-Criticality Real-Time Scheduling

Abstract

While conventional studies on real-time systems have mostly considered the real-time constraint of real-time systems only, recent research initiatives are trying to incorporate a security constraint into realtime scheduling due to the recognition that the violation of either of two constrains can cause catastrophic losses for humans, the system, and even environment. The focus of most studies, however, is the single-criticality systems, while the security of mixed-criticality systems has received scant attention, even though security is also a critical issue for the design of mixed-criticality systems. In this paper, we address the problem of the information leakage that arises from the shared resources that are used by tasks with different security-levels of mixed-criticality systems. We define a new concept of the security constraint employing a pre-flushing mechanism to cleanse the state of shared resources whenever there is a possibility of the information leakage regarding it. Then, we propose a new non-preemptive real-time scheduling algorithm and a schedulability analysis, which incorporate the security constraint for mixed-criticality systems. Our evaluation demonstrated that a large number of real-time tasks can be scheduled without a significant performance loss under a new security constraint.

Optimizing Energy in Non-Preemptive Mixed-Criticality Scheduling by Exploiting Probabilistic Information

“…Two state-of-the-art works [3], [39] proposed an RTA of non-preemptive FP scheduling, but under settings that are different from this paper's focus. We will report the main results in the form of equations to make it easier to follow the subsequent RTA for our problem.…”

“…Baek et al [3] extended the analysis above to MC task model by considering the adaptive MC (AMC) scheme [4], and derived WCRTs for the following three cases separately: Case 1. WCRT at lo-criticality mode for any task τ i is calculated as:…”

“…We instead calculate the WCRT of a hi-criticality task, τ i , by summing the blocking time, WCET of τ i and the worst-case interference from other tasks with a higher priority than τ i . Unlike [3], we do not drop the lo-criticality tasks after a mode-switch. Hence, the lo-criticality tasks can contribute to the interference (even after a mode-switch).…”

A Task Parameter Inference Framework for Real-Time Embedded Systems

“…The papers belonging to the first category add a mechanism of flushing information remaining in computing resources, or integrate additional (periodic) security tasks [9,19,[24][25][26]. Mohan et al [19] focused on fixed priority scheduling (such as RM) on a uniprocessor platform, and proposed how to modify the original scheduling algorithm to accommodate the flushing mechanism, which prevents other tasks from eavesdropping information in computing resources owned by critical tasks.…”

“…Based on [19], Pellizzoni et al [9] explored tradeoffs between security requirements (achieved by the flushing mechanism) and real-time guarantees. Then, the studies for the flushing mechanism were extended towards considering preemption overheads [26] and mixed-criticality systems [25]. On the other hand, Hasan et al [24] developed how to integrate additional (periodic) security tasks without compromising timing guarantees.…”