Practical-Foundations-ARM64 Linus Debugging- Disassembly-Reversing.png

arm.tar.gz

Codeoptmization

Pointers_to_assign

Pointers

MemoryPointers

PointersAsVariables

PointersAsVariables-optimization

SimpleStack

LocalVariables

FunctionParameters

FunctionParameters-14

solution

FunctionParameters-14-copy

RawStack

MemoryPointers-copy

The 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. You’ll use the Linux ARM64 which is a popular RISC architecture. You’ll use simple operations in C/C++ such as assignment, increment, addition, multiplication. With the help of the GDB, you will probe into the contents of the registers and memory. You'll learn how they are changed while executing basic operations. With the help of the disassembly output, you’ll learn how a simple C/C++ program can be reconstructed. The disassembly output is important for debugging and core dump analysis.

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.

Foundations of Linux ARM64: Debug, Disassemble, and Reverse

## Register review
So far, we have seen and used general-purpose CPU registers:
* `x0`/`w0` 
* `x1`/`w1` 
* `x2`/`w2` 
* `x3`/`w3` 
* `x4`/`w4` 
* ...
* `x30`/`w30`

We also have special purpose registers:
* `XZR`/`WZR` (the zero register)
* `pc` (the instruction pointer)
* `sp` (the stack pointer)
## Application memory simplified
When an executable file is loaded into memory, we observe the following:
* Its header and sections are mapped to memory pages.
* Some data and code are copied unmodified, but some data is initialized and expanded. 
* The first stack is also created at this stage.
* A `pc` register is set to point to the first program instruction, and `sp` points to the top of the stack.

This simplified process is shown in the figure below:


# Register review
So far, we have seen and used general-purpose CPU registers:
* `x0`/`w0` 
* `x1`/`w1` 
* `x2`/`w2` 
* `x3`/`w3` 
* `x4`/`w4` 
* ...
* `x30`/`w30`

We also have special purpose registers:
* `XZR`/`WZR` (the zero register)
* `pc` (the instruction pointer)
* `sp` (the stack pointer)
# Application memory simplified
When an executable file is loaded into memory, we observe the following:
* Its header and sections are mapped to memory pages.
* Some data and code are copied unmodified, but some data is initialized and expanded. 
* The first stack is also created at this stage.
* A `pc` register is set to point to the first program instruction, and `sp` points to the top of the stack.

This simplified process is shown in the figure below:


Learn how to implement the stack, call stack, and jumps in memory and registers.

Stack in Memory and Registers

Introduction to the Course

Memory, Registers, and Simple Arithmetic

Code Optimization

Number Representations

Pointers

Bytes, Half Words, Words, and Double Words

Pointers to Memory

Logical Instructions and PC

Reconstructing a Program with Pointers

Memory and Stacks

Frame Pointer and Local Variables

Function Parameters

More Instructions

Function Pointer Parameters

Conclusion

ARM64 Linux Debugging, Disassembling, Reversing Exam

Stack in Memory and Registers

Register review

Application memory simplified