Fine-grained dynamic instrumentation of commodity operating system kernels

Abstract

Operating system kernel code is generally immutable. This trend is unfortunate, because a kernel that can insert (and later remove) code at run-time has many uses, including performance measurement, debugging, code coverage, run-time installation of patches, and run-time optimizations. The research in this dissertation investigates dynamic (run-time) kernel instrumentation and its applications in the areas of kernel profiling and code evolution. We have implemented dynamic kernel instrumentation, a kernel performance monitor, and a run-time kernel optimizer in a system called KernInst. The first component of this dissertation investigates fine-grained dynamic kernel instrumentation, a technology to dynamically modify kernel code. We have designed two primitives for runtime kernel code modification, splicing, which inserts instrumentation code, and code replacement, which replaces a function's code. A part of the KernInst system called kerninstd implements fine-grained dynamic instrume...