Book Image

Linux Kernel Debugging

By : Kaiwan N. Billimoria
Book Image

Linux Kernel Debugging

By: Kaiwan N. Billimoria

Overview of this book

The Linux kernel is at the very core of arguably the world’s best production-quality OS. Debugging it, though, can be a complex endeavor. Linux Kernel Debugging is a comprehensive guide to learning all about advanced kernel debugging. This book covers many areas in-depth, such as instrumentation-based debugging techniques (printk and the dynamic debug framework), and shows you how to use Kprobes. Memory-related bugs tend to be a nightmare – two chapters are packed with tools and techniques devoted to debugging them. When the kernel gifts you an Oops, how exactly do you interpret it to be able to debug the underlying issue? We’ve got you covered. Concurrency tends to be an inherently complex topic, so a chapter on lock debugging will help you to learn precisely what data races are, including using KCSAN to detect them. Some thorny issues, both debug- and performance-wise, require detailed kernel-level tracing; you’ll learn to wield the impressive power of Ftrace and its frontends. You’ll also discover how to handle kernel lockups, hangs, and the dreaded kernel panic, as well as leverage the venerable GDB tool within the kernel (KGDB), along with much more. By the end of this book, you will have at your disposal a wide range of powerful kernel debugging tools and techniques, along with a keen sense of when to use which.
Table of Contents (17 chapters)
1
Part 1: A General Introduction and Approaches to Kernel Debugging
4
Part 2: Kernel and Driver Debugging Tools and Techniques
11
Part 3: Additional Kernel Debugging Tools and Techniques

Summary

With a non-managed programming language such as C, a trade-off exists: high power and the ability to code virtually anything you can imagine but at a significant cost. With memory being managed directly by the programmer, slipping in memory defects – bugs! – of all kinds, is rather easy to do, even for experienced folk.

In this chapter, we covered many tools, techniques, and approaches in this regard. First, you learned about the different (scary) types of memory defects. Then, we delved into how to use various tools and techniques to identify them and thus be able to fix them.

One of the most powerful tools in your arsenal for detecting memory bugs is KASAN. You learned how to configure and use it. We first learned how to use the kernel's built-in KUnit test framework to run memory test cases for KASAN to catch. We then developed our own custom module with test cases and even a neat way to test, via a debugfs pseudofile and custom scripts.

Catching...