1  /* Check DTAUDIT and vDSO interaction.
       2     Copyright (C) 2021-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <link.h>
      20  #include <inttypes.h>
      21  #include <stdbool.h>
      22  #include <string.h>
      23  #include <stdio.h>
      24  #include <sys/auxv.h>
      25  
      26  static inline bool
      27  startswith (const char *str, const char *pre)
      28  {
      29    size_t lenpre = strlen (pre);
      30    size_t lenstr = strlen (str);
      31    return lenstr < lenpre ? false : memcmp (pre, str, lenpre) == 0;
      32  }
      33  
      34  unsigned int
      35  la_version (unsigned int version)
      36  {
      37    return LAV_CURRENT;
      38  }
      39  
      40  unsigned int
      41  la_objopen (struct link_map *map, Lmid_t lmid, uintptr_t *cookie)
      42  {
      43    /* The linux-gate.so is placed at a fixed address, thus l_addr being 0,
      44       and it might be the value reported as the AT_SYSINFO_EHDR.  */
      45    if (map->l_addr == 0 && startswith (map->l_name, "linux-gate.so"))
      46      fprintf (stderr, "vdso found: %p\n", NULL);
      47    else if (map->l_addr == getauxval (AT_SYSINFO_EHDR))
      48      fprintf (stderr, "vdso found: %p\n", (void*) map->l_addr);
      49  
      50    return 0;
      51  }