1/*
2 * vdso_test.c: Sample code to test parse_vdso.c
3 * Copyright (c) 2014 Andy Lutomirski
4 * Subject to the GNU General Public License, version 2
5 *
6 * Compile with:
7 * gcc -std=gnu99 vdso_test.c parse_vdso.c
8 *
9 * Tested on x86, 32-bit and 64-bit.  It may work on other architectures, too.
10 */
11
12#include <stdint.h>
13#include <elf.h>
14#include <stdio.h>
15#include <sys/auxv.h>
16#include <sys/time.h>
17
18extern void *vdso_sym(const char *version, const char *name);
19extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
20extern void vdso_init_from_auxv(void *auxv);
21
22int main(int argc, char **argv)
23{
24	unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR);
25	if (!sysinfo_ehdr) {
26		printf("AT_SYSINFO_EHDR is not present!\n");
27		return 0;
28	}
29
30	vdso_init_from_sysinfo_ehdr(getauxval(AT_SYSINFO_EHDR));
31
32	/* Find gettimeofday. */
33	typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
34	gtod_t gtod = (gtod_t)vdso_sym("LINUX_2.6", "__vdso_gettimeofday");
35
36	if (!gtod) {
37		printf("Could not find __vdso_gettimeofday\n");
38		return 1;
39	}
40
41	struct timeval tv;
42	long ret = gtod(&tv, 0);
43
44	if (ret == 0) {
45		printf("The time is %lld.%06lld\n",
46		       (long long)tv.tv_sec, (long long)tv.tv_usec);
47	} else {
48		printf("__vdso_gettimeofday failed\n");
49	}
50
51	return 0;
52}
53