root/tools/testing/selftests/vDSO/vdso_test.c

DEFINITIONS

1. main

   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 
  20 extern void *vdso_sym(const char *version, const char *name);
  21 extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
  22 extern 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__)
  30 const char *version = "LINUX_2.6.39";
  31 const char *name = "__kernel_gettimeofday";
  32 #else
  33 const char *version = "LINUX_2.6";
  34 const char *name = "__vdso_gettimeofday";
  35 #endif
  36 
  37 int 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 }