1 /*
2 * Non-libc syscall hello world for Aarch64 BE
3 *
4 * SPDX-License-Identifier: GPL-2.0-or-later
5 */
6
7 #define __NR_write 64
8 #define __NR_exit 93
9
write(int fd,char * buf,int len)10 int write(int fd, char *buf, int len)
11 {
12 register int x0 __asm__("x0") = fd;
13 register char *x1 __asm__("x1") = buf;
14 register int x2 __asm__("x2") = len;
15 register int x8 __asm__("x8") = __NR_write;
16
17 asm volatile("svc #0" : : "r"(x0), "r"(x1), "r"(x2), "r"(x8));
18
19 return len;
20 }
21
exit(int ret)22 void exit(int ret)
23 {
24 register int x0 __asm__("x0") = ret;
25 register int x8 __asm__("x8") = __NR_exit;
26
27 asm volatile("svc #0" : : "r"(x0), "r"(x8));
28 __builtin_unreachable();
29 }
30
_start(void)31 void _start(void)
32 {
33 write(1, "Hello World\n", 12);
34 exit(0);
35 }
36