Linux's security measures against executing shellcode

Question

I'm learning the basics of computer security and I'm trying to execute some shellcode I've written. I followed the steps given here

http://dl.packetstormsecurity.net/papers/shellcode/own-shellcode.pdf

http://webcache.googleusercontent.com/search?q=cache:O3uJcNhsksAJ:dl.packetstormsecurity.net/papers/shellcode/own-shellcode.pdf+own+shellcode&cd=1&hl=nl&ct=clnk&gl=nl

$ cat pause.s
xor %eax,%eax
mov $29,%al     
int $0x80       
$ as -o pause.o pause.s
$ ld -o pause pause.o
ld: warning: cannot find entry symbol _start; defaulting to <<some address here>>
$ ./pause 
^C
$ objdump -d ./pause
pause:     file format elf64-x86_64
Disassembly of section .text:
      08048054 <.text>:
      8048054: 31 c0     xor    %eax,%eax
      8048056: b0 1d     mov    $0x1d,%al
      8048058: cd 80     int    $0x8
$

Since I got my pause program to work, I just copied the objdump output to a c file.

test.c:

int main()
{
    char s[] = "\x31\xc0\xb0\x1d\xcd\x80";
    (*(void(*)())s)();
}

But this produces a segfault. Now, this can only be due to security measures of Arch Linux (?). So how can I get this to work?