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__)
28const char *version = "LINUX_2.6.39";
29const char *name = "__kernel_gettimeofday";
30#elif defined(__riscv)
31const char *version = "LINUX_4.15";
32const char *name = "__vdso_gettimeofday";
33#else
34const char *version = "LINUX_2.6";
35const char *name = "__vdso_gettimeofday";
36#endif
37
38int main(int argc, char **argv)
39{
40 unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR);
41 if (!sysinfo_ehdr) {
42 printf("AT_SYSINFO_EHDR is not present!\n");
43 return KSFT_SKIP;
44 }
45
46 vdso_init_from_sysinfo_ehdr(getauxval(AT_SYSINFO_EHDR));
47
48 /* Find gettimeofday. */
49 typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
50 gtod_t gtod = (gtod_t)vdso_sym(version, name);
51
52 if (!gtod) {
53 printf("Could not find %s\n", name);
54 return KSFT_SKIP;
55 }
56
57 struct timeval tv;
58 long ret = gtod(&tv, 0);
59
60 if (ret == 0) {
61 printf("The time is %lld.%06lld\n",
62 (long long)tv.tv_sec, (long long)tv.tv_usec);
63 } else {
64 printf("%s failed\n", name);
65 return KSFT_FAIL;
66 }
67
68 return 0;
69}
70

source code of linux/tools/testing/selftests/vDSO/vdso_test_gettimeofday.c