Kernel-Level Exception Handling

An in-depth look at how the kernel is now confirming the validity of memory access addresses—not for the beginner. The information in this article applies to kernel versions 2.1.08 to 2.1.36. With version 2.1.37, a few of the kernel internals changed. The exception handling did not change, but the compiled code would be slightly different from the included examples.
Summary

The new user access scheme implemented in the 2.1 development kernels of Linux provides an efficient and easy-to-use way to copy data from and to the kernel address space. The added overhead for the average, error-free case is close to zero. Because access and test for accessibility are atomic, the original problem with multi-threaded applications is resolved. This solution meets all four of our requirements.

Figure 1. Execution Flow Chart

The name Jöerg Pommnitz can be found throughout the Linux kernel code. He recently changed jobs and moved without giving us his direction.

______________________

Webinar
One Click, Universal Protection: Implementing Centralized Security Policies on Linux Systems

As Linux continues to play an ever increasing role in corporate data centers and institutions, ensuring the integrity and protection of these systems must be a priority. With 60% of the world's websites and an increasing share of organization's mission-critical workloads running on Linux, failing to stop malware and other advanced threats on Linux can increasingly impact an organization's reputation and bottom line.

Learn More

Sponsored by Bit9

Webinar
Linux Backup and Recovery Webinar

Most companies incorporate backup procedures for critical data, which can be restored quickly if a loss occurs. However, fewer companies are prepared for catastrophic system failures, in which they lose all data, the entire operating system, applications, settings, patches and more, reducing their system(s) to “bare metal.” After all, before data can be restored to a system, there must be a system to restore it to.

In this one hour webinar, learn how to enhance your existing backup strategies for better disaster recovery preparedness using Storix System Backup Administrator (SBAdmin), a highly flexible bare-metal recovery solution for UNIX and Linux systems.

Learn More

Sponsored by Storix