elf/do-rel.h

   1 /* Do relocations for ELF dynamic linking.
   2    Copyright (C) 1995,96,97,98,99,2000,2001 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 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 RELCOUNT_IDX                   VERSYMIDX (DT_RELACOUNT)
  26 # define Rel                            Rela
  27 # define elf_machine_rel                elf_machine_rela
  28 # define elf_machine_rel_relative       elf_machine_rela_relative
  29 #else
  30 # define RELCOUNT_IDX                   VERSYMIDX (DT_RELCOUNT)
  31 #endif
  32
  33 #ifndef VERSYMIDX
  34 # define VERSYMIDX(sym) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (sym))
  35 #endif
  36
  37 /* Perform the relocations in MAP on the running program image as specified
  38    by RELTAG, SZTAG.  If LAZY is nonzero, this is the first pass on PLT
  39    relocations; they should be set up to call _dl_runtime_resolve, rather
  40    than fully resolved now.  */
  41
  42 static inline void
  43 elf_dynamic_do_rel (struct link_map *map,
  44                     ElfW(Addr) reladdr, ElfW(Addr) relsize,
  45                     int lazy)
  46 {
  47   const ElfW(Rel) *r = (const void *) reladdr;
  48   const ElfW(Rel) *end = (const void *) (reladdr + relsize);
  49   ElfW(Addr) l_addr = map->l_addr;
  50
  51 #ifndef RTLD_BOOTSTRAP
  52   /* We never bind lazily during ld.so bootstrap.  Unfortunately gcc is
  53      not clever enough to see through all the function calls to realize
  54      that.  */
  55   if (lazy)
  56     {
  57       /* Doing lazy PLT relocations; they need very little info.  */
  58       for (; r < end; ++r)
  59         elf_machine_lazy_rel (map, l_addr, r);
  60     }
  61   else
  62 #endif
  63     {
  64       const ElfW(Sym) *const symtab =
  65         (const void *) D_PTR (map, l_info[DT_SYMTAB]);
  66       ElfW(Word) nrelative = (map->l_info[RELCOUNT_IDX] == NULL
  67                               ? 0 : map->l_info[RELCOUNT_IDX]->d_un.d_val);
  68       const ElfW(Rel) *relative = r;
  69       r = MIN (r + nrelative, end);
  70
  71 #ifndef RTLD_BOOTSTRAP
  72       /* This is defined in rtld.c, but nowhere in the static libc.a; make
  73          the reference weak so static programs can still link.  This
  74          declaration cannot be done when compiling rtld.c (i.e. #ifdef
  75          RTLD_BOOTSTRAP) because rtld.c contains the common defn for
  76          _dl_rtld_map, which is incompatible with a weak decl in the same
  77          file.  */
  78       weak_extern (_dl_rtld_map);
  79       if (map != &_dl_rtld_map) /* Already done in rtld itself.  */
  80 # ifndef DO_RELA
  81         /* Rela platforms get the offset from r_addend and this must
  82            be copied in the relocation address.  Therefore we can skip
  83            the relative relocations only if this is for rel
  84            relocations.  */
  85         if (l_addr != 0)
  86 # endif
  87 #endif
  88           for (; relative < r; ++relative)
  89             elf_machine_rel_relative (l_addr, relative,
  90                                       (void *) (l_addr + relative->r_offset));
  91
  92       if (map->l_info[VERSYMIDX (DT_VERSYM)])
  93         {
  94           const ElfW(Half) *const version =
  95             (const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]);
  96
  97           for (; r < end; ++r)
  98             {
  99               ElfW(Half) ndx = version[ELFW(R_SYM) (r->r_info)];
 100               elf_machine_rel (map, r, &symtab[ELFW(R_SYM) (r->r_info)],
 101                                &map->l_versions[ndx],
 102                                (void *) (l_addr + r->r_offset));
 103             }
 104         }
 105       else
 106         for (; r < end; ++r)
 107           elf_machine_rel (map, r, &symtab[ELFW(R_SYM) (r->r_info)], NULL,
 108                            (void *) (l_addr + r->r_offset));
 109     }
 110 }
 111
 112 #undef elf_dynamic_do_rel
 113 #undef Rel
 114 #undef elf_machine_rel
 115 #undef elf_machine_rel_relative
 116 #undef RELCOUNT_IDX