LXR linux/tools/testing/selftests/vDSO/vdso

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * vdso_test.c: Sample code to test parse_vdso.c
   4 * Copyright (c) 2014 Andy Lutomirski
   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
  18#include "../kselftest.h"
  19
  20extern void *vdso_sym(const char *version, const char *name);
  21extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
  22extern void vdso_init_from_auxv(void *auxv);
  23
  24/*
  25 * ARM64's vDSO exports its gettimeofday() implementation with a different
  26 * name and version from other architectures, so we need to handle it as
  27 * a special case.
  28 */
  29#if defined(__aarch64__)
  30const char *version = "LINUX_2.6.39";
  31const char *name = "__kernel_gettimeofday";
  32#else
  33const char *version = "LINUX_2.6";
  34const char *name = "__vdso_gettimeofday";
  35#endif
  36
  37int main(int argc, char **argv)
  38{
  39        unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR);
  40        if (!sysinfo_ehdr) {
  41                printf("AT_SYSINFO_EHDR is not present!\n");
  42                return KSFT_SKIP;
  43        }
  44
  45        vdso_init_from_sysinfo_ehdr(getauxval(AT_SYSINFO_EHDR));
  46
  47        /* Find gettimeofday. */
  48        typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
  49        gtod_t gtod = (gtod_t)vdso_sym(version, name);
  50
  51        if (!gtod) {
  52                printf("Could not find %s\n", name);
  53                return KSFT_SKIP;
  54        }
  55
  56        struct timeval tv;
  57        long ret = gtod(&tv, 0);
  58
  59        if (ret == 0) {
  60                printf("The time is %lld.%06lld\n",
  61                       (long long)tv.tv_sec, (long long)tv.tv_usec);
  62        } else {
  63                printf("%s failed\n", name);
  64                return KSFT_FAIL;
  65        }
  66
  67        return 0;
  68}
  69