nasm hello world segmentation fault

rblampain · 05-27-2014, 05:00 AM

I have the following code which works but gives a segmentation fault after printing the message to STDOUT, I have no idea what the problem could be.

Could someone help? (I do not know C)

Code:

[bits 64]
section .data
message:
    db      'hello, world!', 0
section .text
global _start
_start:
    mov     rax, 4
    mov     rdi, 1
    mov     rsi, message
    mov     rdx, 13
    syscall

    mov     rax, 1
    xor     rdi, rdi
    syscall

Here are the commands used:
nasm -f elf64 -o hello.o hello.asm
ld -o hello hello.o
./hello

Debian 7
gcc 4.7.2-5
yasm 1.1.0-1
nasm 2.10.01-1
linker ???

Thank you for your help.

smallpond · 05-27-2014, 12:43 PM

Your syscall interface seems wrong. syscall requires call number in rax, args in rbx, rcx, rdx ...

rblampain · 06-07-2014, 04:05 AM

Thank you for your answer but arguments go in rax, rdi, rsi, rdx, rcx, r8, r9 in that order.

ntubski · 06-07-2014, 09:11 AM

According to this x64 hello world example (which works), you have your syscall numbers wrong.