EteimZ / x86_asm

My introduction to the x86-64 architecture

x86_asm

This repo contains guides and resources I am using to learn x86 assembly 64 bit.

Registers

x86 has registers which are used to store values and addresses. They come in various sizes: 64 bits, 32 bits, 16 bits. My primary focus is the 64 bit registers.

General purpose registers

• rax
• rbx
• rcx
• rdx
• rsi

Special purpose registers

• rbp: This register stores the base pointer in the stack.
• rsp: This register stores the stack pointer. It represents the top of the stack.
• rip: This register stores the current working address.

Istruction set

• mov: Moves values to a register. mov rax, 0x2
• add: Performs addition. add arg1, arg2 == arg1 = arg1 + arg2
• sub: Performs subtraction. sub arg1, arg2 == arg1 = arg1 - arg2
• push: Decrements the stack pointer and add a value to the stack.
• pop: Increments the stack pointer and removes a value and adds it to a register.
• lea: Load effective address. Adds an address to a register.
• cmp: Compare its arguments and sets a flag.
• jmp: Jump to a particular address.
• je: Jump if equal to.
• jne: Jump not equal to.
• jg: JUmp if greater than.
• call: Call a function.
• ret
• leave

Tools for reverse engineering

• strings
• objdump
• radare2
• gdb
• l/strace
• hexdump

References

• x86 Assembly Guide
• registes in x86 assembly