sysdeps/unix/sysv/linux/dl-parse_auxv.h

   1 /* Parse the Linux auxiliary vector.
   2    Copyright (C) 1995-2024 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 <elf.h>
  20 #include <entry.h>
  21 #include <fpu_control.h>
  22 #include <ldsodefs.h>
  23 #include <link.h>
  24
  25 typedef ElfW(Addr) dl_parse_auxv_t[AT_MINSIGSTKSZ + 1];
  26
  27 /* Copy the auxiliary vector into AUXV_VALUES and set up GLRO
  28    variables.  */
  29 static inline
  30 void _dl_parse_auxv (ElfW(auxv_t) *av, dl_parse_auxv_t auxv_values)
  31 {
  32   auxv_values[AT_ENTRY] = (ElfW(Addr)) ENTRY_POINT;
  33   auxv_values[AT_PAGESZ] = EXEC_PAGESIZE;
  34   auxv_values[AT_FPUCW] = _FPU_DEFAULT;
  35
  36   /* NB: Default to a constant CONSTANT_MINSIGSTKSZ.  */
  37   _Static_assert (__builtin_constant_p (CONSTANT_MINSIGSTKSZ),
  38                   "CONSTANT_MINSIGSTKSZ is constant");
  39   auxv_values[AT_MINSIGSTKSZ] = CONSTANT_MINSIGSTKSZ;
  40
  41   for (; av->a_type != AT_NULL; av++)
  42     if (av->a_type <= AT_MINSIGSTKSZ)
  43       auxv_values[av->a_type] = av->a_un.a_val;
  44
  45   GLRO(dl_pagesize) = auxv_values[AT_PAGESZ];
  46   __libc_enable_secure = auxv_values[AT_SECURE];
  47   GLRO(dl_platform) = (void *) auxv_values[AT_PLATFORM];
  48   GLRO(dl_hwcap) = auxv_values[AT_HWCAP];
  49   GLRO(dl_hwcap2) = auxv_values[AT_HWCAP2];
  50   GLRO(dl_clktck) = auxv_values[AT_CLKTCK];
  51   GLRO(dl_fpu_control) = auxv_values[AT_FPUCW];
  52   _dl_random = (void *) auxv_values[AT_RANDOM];
  53   GLRO(dl_minsigstacksize) = auxv_values[AT_MINSIGSTKSZ];
  54   GLRO(dl_sysinfo_dso) = (void *) auxv_values[AT_SYSINFO_EHDR];
  55 #ifdef NEED_DL_SYSINFO
  56   if (GLRO(dl_sysinfo_dso) != NULL)
  57     GLRO(dl_sysinfo) = auxv_values[AT_SYSINFO];
  58 #endif
  59
  60   DL_PLATFORM_AUXV
  61 }