Book Image

Linux Kernel Programming

By : Kaiwan N. Billimoria
Book Image

Linux Kernel Programming

By: Kaiwan N. Billimoria

Overview of this book

Linux Kernel Programming is a comprehensive introduction for those new to Linux kernel and module development. This easy-to-follow guide will have you up and running with writing kernel code in next-to-no time. This book uses the latest 5.4 Long-Term Support (LTS) Linux kernel, which will be maintained from November 2019 through to December 2025. By working with the 5.4 LTS kernel throughout the book, you can be confident that your knowledge will continue to be valid for years to come. You’ll start the journey by learning how to build the kernel from the source. Next, you’ll write your first kernel module using the powerful Loadable Kernel Module (LKM) framework. The following chapters will cover key kernel internals topics including Linux kernel architecture, memory management, and CPU scheduling. During the course of this book, you’ll delve into the fairly complex topic of concurrency within the kernel, understand the issues it can cause, and learn how they can be addressed with various locking technologies (mutexes, spinlocks, atomic, and refcount operators). You’ll also benefit from more advanced material on cache effects, a primer on lock-free techniques within the kernel, deadlock avoidance (with lockdep), and kernel lock debugging techniques. By the end of this kernel book, you’ll have a detailed understanding of the fundamentals of writing Linux kernel module code for real-world projects and products.
Table of Contents (19 chapters)
1
Section 1: The Basics
6
Writing Your First Kernel Module - LKMs Part 2
7
Section 2: Understanding and Working with the Kernel
10
Kernel Memory Allocation for Module Authors - Part 1
11
Kernel Memory Allocation for Module Authors - Part 2
14
Section 3: Delving Deeper
17
About Packt

Viewing the user space stack of a given thread or process

Ironically, viewing the user space stack of a process or thread seems harder to do on a typical Linux distro (as opposed to viewing the kernel-mode stack, as we just saw in the previous section). There is a utility to do so: gstack(1). In reality, it's just a simple wrapper over a script that invokes gdb(1) in batch mode, getting gdb to invoke its backtrace command.

Unfortunately, on Ubuntu (18.04 LTS at least), there seems to be an issue; the gstack program was not found in any native package. (Ubuntu does have a pstack(1) utility, but, at least on my test VM, it failed to work well.) A workaround is to simply use gdb directly (you can always attach <PID> and issue the [thread apply all] bt command to view the user mode stack(s)).

On my x86_64 Fedora 29 guest system, though, the gstack(1) utility cleanly installs and runs well; an example is as follows (our Bash process' PID here happens to...