Redesigning the Interrupt-Handling Architecture of Tock OS

Abstract

The increasing complexity of embedded applications and the rapid proliferation of the Internet of Things necessitates that embedded devices operate securely. Tock OS is an embedded operating system built in Rust that provides safety and isolation guarantees via a combination of programming-language and hardware-based protection mechanisms. Currently, Tock handles interrupts synchronously in privileged thread mode, utilizing software rerouting to map active interrupts to their corresponding service routine within the kernel. This paper proposes a redesigned Tock kernel that handles interrupts directly in handler mode while preserving safety semantics, with the goal of reducing code complexity and improving interrupt-handling performance. To demonstrate the viability of this proposed kernel restructuring, this paper presents a proof of concept that modifies the original Tock kernel to schedule and run a singular process, and handle the ‘LED toggle’ SVC call directly in handler mode. Initial performance benchmarks conducted on the kernel prototype indicate that it has a lower interrupt-handling latency than the existing Tock kernel; this serves to demonstrate the potential benefits of adopting this new kernel architecture.