Book Image

Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization

By : Kaiwan N. Billimoria
Book Image

Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization

By: Kaiwan N. Billimoria

Overview of this book

Linux Kernel Programming Part 2 - Char Device Drivers and Kernel Synchronization is an ideal companion guide to the Linux Kernel Programming book. This book provides a comprehensive introduction for those new to Linux device driver development and will have you up and running with writing misc class character device driver code (on the 5.4 LTS Linux kernel) in next to no time. You'll begin by learning how to write a simple and complete misc class character driver before interfacing your driver with user-mode processes via procfs, sysfs, debugfs, netlink sockets, and ioctl. You'll then find out how to work with hardware I/O memory. The book covers working with hardware interrupts in depth and helps you understand interrupt request (IRQ) allocation, threaded IRQ handlers, tasklets, and softirqs. You'll also explore the practical usage of useful kernel mechanisms, setting up delays, timers, kernel threads, and workqueues. Finally, you'll discover how to deal with the complexity of kernel synchronization with locking technologies (mutexes, spinlocks, and atomic/refcount operators), including more advanced topics such as cache effects, a primer on lock-free techniques, deadlock avoidance (with lockdep), and kernel lock debugging techniques. By the end of this Linux kernel book, you'll have learned the fundamentals of writing Linux character device driver code for real-world projects and products.
Table of Contents (11 chapters)
Section 1: Character Device Driver Basics
User-Kernel Communication Pathways
Handling Hardware Interrupts
Working with Kernel Timers, Threads, and Workqueues
Section 2: Delving Deeper


  1. On an x86 system (a VM is fine), show that while the number of timer interrupts (IRQ 0) remains the same, another periodic system interrupt is actually continually incrementing (hence keeping track of time on a per-CPU basis).
    Hint: use a proc pseudo-file associated with interrupts.
  2. keylogger_simple ; native x86 only  [use only for ethical hacking; may not work on a VM]
    (A bit more advanced) Write a simple keyboard logger driver using the "misc" kernel framework. Trap it inside the i8042's IRQ 1 in order to "trap" it inside the keyboard press/release and read the key scancode. Use a kfifo data structure to hold the keyboard scancode in kernel space memory. Have a user mode process (or thread) periodically read the data items from your driver's kfifo into a user space buffer and write them into a log file. Write an app (or use another thread) to interpret the keyboard keys.
    1. Can you ensure that it runs only...