;name: elf64header.asm
;
;build: chmod -f elf64header && nasm -fbin -o elf64header elf64header.asm && chmod +x elf64header
;
;description: Small, self-contained 64-bit ELF executable for NASM
;
;adapted from: http://www.muppetlabs.com/~breadbox/software/tiny/teensy.html
;http://blog.markloiseau.com/2012/05/tiny-64-bit-elf-executables/
bits 64
[list -]
%include "unistd.inc"
[list +]
org 0x00400000 ;Program load offset
;64-bit ELF header
ehdr:
;ELF Magic + 2 (64-bit), 1 (LSB), 1 (ELF ver. 1), 0 (ABI ver.)
db 0x7F, "ELF", 2, 1, 1, 0 ;e_ident
times 8 db 0 ;reserved (zeroes)
dw 2 ;e_type: Executable file
dw 0x3e ;e_machine: AMD64
dd 1 ;e_version: current version
dq _start ;e_entry: program entry address (0x78)
dq phdr - $$ ;e_phoff program header offset (0x40)
dq 0 ;e_shoff no section headers
dd 0 ;e_flags no flags
dw ehdrsize ;e_ehsize: ELF header size (0x40)
dw phdrsize ;e_phentsize: program header size (0x38)
dw 1 ;e_phnum: one program header
dw 0 ;e_shentsize
dw 0 ;e_shnum
dw 0 ;e_shstrndx
ehdrsize equ $ - ehdr
;64-bit ELF program header
phdr:
dd 1 ;p_type: loadable segment
dd 5 ;p_flags read and execute
dq 0 ;p_offset
dq $$ ;p_vaddr: start of the current section
dq $$ ;p_paddr:
dq filesize ;p_filesz
dq filesize ;p_memsz
dq 0x200000 ;p_align: 2^11=200000=11 bit boundaries
;program header size
phdrsize equ $ - phdr
;Hello World!/your program here
_start:
xor rax,rax ;3 bytes
mov edi,1 ;5 bytes
mov esi,message ;5 bytes
mov edx,message.len ;5 bytes
inc rax ;3 bytes
syscll:
syscall ;2 bytes
dec rdi ;3 bytes
add al,0x3b ;2 bytes
jmp syscll ;2 bytes
;----------
;30 bytes
message: db 'Hello, world!',0x0A ;message and newline
.len: equ $-message ;message length calculation
; File size calculation
filesize equ $ - $$
