Gain insights into using GDB for debugging in Linux. Explore disassembly, memory investigation, and register updates. Learn about pointers, stack, and function parameters in x64 architecture.

gdb.tar.gz

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GNU Debugger (GDB) is used for debugging C/C++ programs in LINUX/UNIX environments. It is a good tool to investigate what is happening inside a program, and how the contents inside the memory are changed with the execution of the program.

The main focus of the course is the disassembly of the program, where we'll use simple operations in C. With the help of GDB, we'll examine the contents of the registers and memory. We'll also learn how they are changed while executing basic operations. We’ll then explore the use of pointers, stack, and function parameters, and analyze how different registers update their values. With the help of disassembly output, we’ll learn how a simple C program can be reconstructed. The disassembly output is important for debugging and core dump analysis. We’ll use assembly language for x64 architecture.

By the end of this course, you should be able to debug the programs and memory contents at assembly level when a program executes or probe into the problem when a program crashes.

Debugging, Disassembly & Reversing in Linux for x64 Architecture

# Granularity
Memory is divided into **granule**s, or chunks of different sizes, to store data fields. Granules help us manage and access data in an organized way. 

Fine and coarse granularity both have advantages and disadvantages. On one hand, **fine granularity** _may cause input and storage overheads_, but on the other, **coarse granularity** _offers less flexibility in changing parts of the data_.

Memory space is generally divided into bytes, halfwords, words, and double words.

# Using hexadecimal numbers
The **hexadecimal** number system has a base value of $16$.

## Hexadecimal representation in C/C++
To indicate that we are using hexadecimal numbers in C/C++ language, we prefix them with `0x`. For example:


Learn how to compare bytes, halfwords, words, and double words in terms of granularity.

Granularity

Introduction to the Course

Memory, Registers, and Simple Arithmetic

Code Optimization

Number Representations

Pointers

Bytes, Words, Double, and Quad Words

Pointers to Memory

Logical Instructions and RIP

Reconstructing a Program with Pointers

Memory and Stacks

Frame Pointer and Local Variables

Function Parameters

More Instructions

Function Pointer Parameters

Summary of Code Disassembly Patterns

x64 Debugging, Disassembly & Reversing Exam

Granularity

Granularity