Custom Exception Handlers
Explore how to write and register your own custom exception handlers to manage specific error conditions at the lowest level.
Intercepting System Errors
Custom exception handlers are special routines that take control when the CPU encounters an unexpected event, known as an exception. These events can range from programming errors like dividing by zero to memory access violations.
Instead of the system crashing, a custom handler allows you to intercept these events, diagnose the problem, or even recover gracefully. This is crucial for operating systems and low-level debugging.
CPU's Response to Exceptions
When an exception occurs, the CPU performs a series of critical steps before executing any handler code:
- It pushes the current EFLAGS, CS (Code Segment), and EIP (Instruction Pointer) onto the stack.
- For some exceptions (like page faults), an error code is also pushed.
- The CPU then looks up the corresponding entry in the Interrupt Descriptor Table (IDT) to find the address of the exception handler.
- Finally, it transfers control to that handler.