1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * vdso_test_gettimeofday.c: Sample code to test parse_vdso.c and
4  *                           vDSO gettimeofday()
5  * Copyright (c) 2014 Andy Lutomirski
6  *
7  * Compile with:
8  * gcc -std=gnu99 vdso_test_gettimeofday.c parse_vdso_gettimeofday.c
9  *
10  * Tested on x86, 32-bit and 64-bit.  It may work on other architectures, too.
11  */
12 
13 #include <stdint.h>
14 #include <elf.h>
15 #include <stdio.h>
16 #include <sys/auxv.h>
17 #include <sys/time.h>
18 
19 #include "../kselftest.h"
20 #include "parse_vdso.h"
21 
22 /*
23  * ARM64's vDSO exports its gettimeofday() implementation with a different
24  * name and version from other architectures, so we need to handle it as
25  * a special case.
26  */
27 #if defined(__aarch64__)
28 const char *version = "LINUX_2.6.39";
29 const char *name = "__kernel_gettimeofday";
30 #else
31 const char *version = "LINUX_2.6";
32 const char *name = "__vdso_gettimeofday";
33 #endif
34 
35 int main(int argc, char **argv)
36 {
37 	unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR);
38 	if (!sysinfo_ehdr) {
39 		printf("AT_SYSINFO_EHDR is not present!\n");
40 		return KSFT_SKIP;
41 	}
42 
43 	vdso_init_from_sysinfo_ehdr(getauxval(AT_SYSINFO_EHDR));
44 
45 	/* Find gettimeofday. */
46 	typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
47 	gtod_t gtod = (gtod_t)vdso_sym(version, name);
48 
49 	if (!gtod) {
50 		printf("Could not find %s\n", name);
51 		return KSFT_SKIP;
52 	}
53 
54 	struct timeval tv;
55 	long ret = gtod(&tv, 0);
56 
57 	if (ret == 0) {
58 		printf("The time is %lld.%06lld\n",
59 		       (long long)tv.tv_sec, (long long)tv.tv_usec);
60 	} else {
61 		printf("%s failed\n", name);
62 		return KSFT_FAIL;
63 	}
64 
65 	return 0;
66 }
67