# as why.asm -o why.o # ld why.o -e start -static -o why .global start
.equ SYS_EXIT, 0x01 .equ SYS_WRITE, 0x04 .equ STD_OUT, 0x01 # this example works in linux (with changed syscalls) # also in netbsd, but not in openbsd. why? .macro sys syscall .endm .text start: # print first message leaq msg1 (%rip), %rsi call print # print second message leaq msg2 (%rip), %rsi call print # print first message, but # this time from the array movq array (%rip), %rsi call print exit: movl $SYS_EXIT, %eax subl %edi, %edi sys # prints 9-char string # in %rsi address of string print: push %rax push %rcx push %rdx push %rdi push %r11 movl $9, %edx # string length movl $STD_OUT, %edi movl $SYS_WRITE, %eax sys pop %r11 pop %rdi pop %rdx pop %rcx pop %rax ret .data msg1: .ascii "string 1\n" msg2: .ascii "string 2\n" array: .quad msg1, msg2 .section ".note.openbsd.ident", "a" .align 2 .long 8, 4, 1 .asciz "OpenBSD" .long 0 .align 2
