The stack, heap, registers and instructions

cs.md

Stack, Heap, Registers and Instructions

1. Stack (push, pop, stack pointer, stack frame pointer)
2. Heap (malloc, calloc, global, static)
3. Registers (addresses, values)
4. Instructions (mov, add, jmp, jne)

The Stack (LIFO)

• push adds an element to the top of the stack
• pop removes the top element from the stack
• each element has a stack address
• the stack grows towards lower memory addresses (windows)
  • elements near the top of the stack have a lower address
  • elements near the bottom of the stack have a higher address
• whenever a function is called that function is set up with a stack frame
• all the local variables of the function are stored in that function's stack frame
  • ebp register, aka the base pointer, contains the address for the current stack frame
  • esp register, aka the stack pointer, points to the top element of the current stack frame

The Heap

TBC

Registers

• 6 General Purpose Registers (eax ebx ecx edx esi edi)
• 3 Reserved Registers (ebp esp eip)
  • eip - instruction pointer
  • esp - stack pointer
  • ebp - (frame) base pointer

Instructions

• mov, push, pop
• add, sub
• cmp
• jmp
• nop
• call
• inc
• ret
• lea
• je, jne, jle, jg