hello.S

    .section    .text
_start:
    sub $0xe, %rsp
    movb $0x48, 0x0(%rsp)
    movb $0x65, 0x1(%rsp)
    movb $0x6c, 0x2(%rsp)
    movb $0x6c, 0x3(%rsp)
    movb $0x6f, 0x4(%rsp)
    movb $0x20, 0x5(%rsp)
    movb $0x57, 0x6(%rsp)
    movb $0x6f, 0x7(%rsp)
    movb $0x72, 0x8(%rsp)
    movb $0x6c, 0x9(%rsp)
    movb $0x64, 0xa(%rsp)
    movb $0x21, 0xb(%rsp)
    movb $0x0a, 0xc(%rsp)
    movb $0x00, 0xd(%rsp)

    movb $0x20, 0xc(%rsp)
    mov %rsp, %rdi
    callq puts

    movb $0x0a, 0xc(%rsp)
    mov $0xe, %rdx
    mov %rsp, %rsi
    mov $0x2, %rdi
    mov $0x1, %rax
    syscall

    mov $0x0, %rdi
    callq fflush

    add $0xe, %rsp
    mov $0x3c, %rax
    syscall
    .global        _start
    .end