elf/do-rel.h

   1 /* Do relocations for ELF dynamic linking.
   2 Copyright (C) 1995, 1996 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 Library General Public License as
   7 published by the Free Software Foundation; either version 2 of the
   8 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 Library General Public License for more details.
  14
  15 You should have received a copy of the GNU Library General Public
  16 License along with the GNU C Library; see the file COPYING.LIB.  If
  17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  18 Cambridge, MA 02139, USA.  */
  19
  20 /* This file may be included twice, to define both
  21    `elf_dynamic_do_rel' and `elf_dynamic_do_rela'.  */
  22
  23 #ifdef DO_RELA
  24 #define elf_dynamic_do_rel      elf_dynamic_do_rela
  25 #define Elf32_Rel               Elf32_Rela
  26 #define elf_machine_rel         elf_machine_rela
  27 #endif
  28
  29
  30 /* Perform the relocations in MAP on the running program image as specified
  31    by RELTAG, SZTAG.  *RESOLVE is called to resolve symbol values; it
  32    modifies its argument pointer to point to the defining symbol, and
  33    returns the base load address of the defining object.  If LAZY is
  34    nonzero, this is the first pass on PLT relocations; they should be set
  35    up to call _dl_runtime_resolve, rather than fully resolved now.  */
  36
  37 static inline void
  38 elf_dynamic_do_rel (struct link_map *map,
  39                     int reltag, int sztag,
  40                     Elf32_Addr (*resolve) (const Elf32_Sym **symbol,
  41                                            Elf32_Addr r_offset),
  42                     int lazy)
  43 {
  44   const Elf32_Sym *const symtab
  45     = (const Elf32_Sym *) (map->l_addr + map->l_info[DT_SYMTAB]->d_un.d_ptr);
  46   const Elf32_Rel *r
  47     = (const Elf32_Rel *) (map->l_addr + map->l_info[reltag]->d_un.d_ptr);
  48   const Elf32_Rel *end = &r[map->l_info[sztag]->d_un.d_val / sizeof *r];
  49
  50   if (lazy)
  51     /* Doing lazy PLT relocations; they need very little info.  */
  52     for (; r < end; ++r)
  53       elf_machine_lazy_rel (map, r);
  54   else
  55     for (; r < end; ++r)
  56       {
  57         const Elf32_Sym *definer = &symtab[ELF32_R_SYM (r->r_info)];
  58         Elf32_Addr loadbase;
  59
  60         if (ELF32_R_SYM (r->r_info) == STN_UNDEF)
  61           loadbase = 0;         /* This value will not be consulted.  */
  62         else if (ELF32_ST_BIND (definer->st_info) == STB_LOCAL)
  63           /* Local symbols always refer to the containing object.  */
  64           loadbase = map->l_addr;
  65         else
  66           {
  67             if (resolve)
  68               loadbase = (*resolve) (&definer, r->r_offset);
  69             else
  70               {
  71                 assert (definer->st_shndx != SHN_UNDEF);
  72                 loadbase = map->l_addr;
  73               }
  74           }
  75         elf_machine_rel (map, r, loadbase, definer);
  76       }
  77 }
  78
  79 #undef elf_dynamic_do_rel
  80 #undef Elf32_Rel
  81 #undef elf_machine_rel