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

Classifying bug types

As you will know, defects (bugs) can be quite readily classified into different types. Here, I attempt to do so (it's nothing new, really), with an added twist: we shall look at common bug classes through different lenses or viewpoints – first, in the classic (typical, academic) manner, then focused on memory-type bugs, and then the security-related view of bugs. Having seen this, we'll further refine this classification to what you'll typically see when working with the Linux kernel. Do note that there can be, and often are, overlaps within these classifications. Let's begin with the first one – classifying defects/bugs in a classic manner.

Types of bugs – the classic view

The classic way of viewing the types of defects or bugs that can occur in a software program is as follows:

  • Logic or implementation errors:
    • Includes off-by-one errors, infinite loops/recursion.
    • Arithmetic errors: Includes loss of precision...