section .data
    msg db "Hello world!", 0ah

section .text
    global _start

_start:
    mov rax, 15
    mov rbx, 2
    add rax, rbx
    mov rdi, rax
  mov rbx, 6
  sub rax, rbx
   mov rbx, 2
   imul rbx
  mov rdi, rax
   mov rax, 60         ; Codice della sys_exit in Linux x86_64
    syscall