ECE MS Thesis Defense: Fredrik Wilke

ECE MS Thesis Defense: Fredrik Wilke

Title: Kernel as a Shared Object: Dynamic Privilege with Dynamic Linking

Advisor: Professor Orran Krieger

Committee: Professor Manuel Egele & Professor Jonathan Appavoo

Abstract: Uni-kernels have demonstrated that Kcuts, short-cuts from application to kernel code, are a powerful optimization technique in the construction of systems dedicated to a single task. Previous work has suggested that the power of such short-cuts can be naturally extended to a general purpose Operating System (OS) with modest effort. Support for Kcuts within an existing general purpose OS opens the door to a new approach for constructing optimized dedicated runtimes. Rather than conforming to the constraints of a uni-kernel, one can construct a runtime from an unrestricted set of user software while having the freedom to develop and exploit Kcuts for the task-critical binaries and libraries. The design focuses on making Kcuts an additive, optional, execution-time property that can be easily added to an OS kernel, in contrast to being a systemic property that impacts the complete design and implementation of the kernel and user software. In line with this, the OS side implementation only adds a new system call and a small attendant set of supporting kernel changes. The user-side implementation that allows applications to utilise kernel functions and data structures is the focus of this work. It presents a novel application and linkage model that allows for efficient application development and portability. This enables user binaries and libraries to be developed to enact particular kcut-based optimizations while integrating and exploiting the rich existing ecosystem of the OS. Overall, this work demonstrates Kcut optimization can enable performance increases akin to uni-kernel’s and yet be a standard feature of a general purpose OS.