elf/do-rel.h

   1 /* Do relocations for ELF dynamic linking.
   2    Copyright (C) 1995,96,97,98,99,2000,2001,2002 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 #ifndef VALIDX
  37 # define VALIDX(tag) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM \
  38                       + DT_EXTRANUM + DT_VALTAGIDX (tag))
  39 #endif
  40
  41 /* Perform the relocations in MAP on the running program image as specified
  42    by RELTAG, SZTAG.  If LAZY is nonzero, this is the first pass on PLT
  43    relocations; they should be set up to call _dl_runtime_resolve, rather
  44    than fully resolved now.  */
  45
  46 static inline void
  47 elf_dynamic_do_rel (struct link_map *map,
  48                     ElfW(Addr) reladdr, ElfW(Addr) relsize,
  49                     int lazy)
  50 {
  51   const ElfW(Rel) *r = (const void *) reladdr;
  52   const ElfW(Rel) *end = (const void *) (reladdr + relsize);
  53   ElfW(Addr) l_addr = map->l_addr;
  54
  55 #if (!defined DO_RELA || !defined ELF_MACHINE_PLT_REL) && !defined RTLD_BOOTSTRAP
  56   /* We never bind lazily during ld.so bootstrap.  Unfortunately gcc is
  57      not clever enough to see through all the function calls to realize
  58      that.  */
  59   if (lazy)
  60     {
  61       /* Doing lazy PLT relocations; they need very little info.  */
  62       for (; r < end; ++r)
  63         elf_machine_lazy_rel (map, l_addr, r);
  64     }
  65   else
  66 #endif
  67     {
  68       const ElfW(Sym) *const symtab =
  69         (const void *) D_PTR (map, l_info[DT_SYMTAB]);
  70       ElfW(Word) nrelative = (map->l_info[RELCOUNT_IDX] == NULL
  71                               ? 0 : map->l_info[RELCOUNT_IDX]->d_un.d_val);
  72       const ElfW(Rel) *relative = r;
  73       r = MIN (r + nrelative, end);
  74
  75 #ifndef RTLD_BOOTSTRAP
  76       /* This is defined in rtld.c, but nowhere in the static libc.a; make
  77          the reference weak so static programs can still link.  This
  78          declaration cannot be done when compiling rtld.c (i.e. #ifdef
  79          RTLD_BOOTSTRAP) because rtld.c contains the common defn for
  80          _dl_rtld_map, which is incompatible with a weak decl in the same
  81          file.  */
  82 # ifndef SHARED
  83       weak_extern (GL(dl_rtld_map));
  84 # endif
  85       if (map != &GL(dl_rtld_map)) /* Already done in rtld itself.  */
  86 # ifndef DO_RELA
  87         /* Rela platforms get the offset from r_addend and this must
  88            be copied in the relocation address.  Therefore we can skip
  89            the relative relocations only if this is for rel
  90            relocations...  */
  91         if (l_addr != 0)
  92 # else
  93         /* ...or we know the object has been prelinked.  */
  94         if (l_addr != 0 || ! map->l_info[VALIDX(DT_GNU_PRELINKED)])
  95 # endif
  96 #endif
  97           for (; relative < r; ++relative)
  98             elf_machine_rel_relative (l_addr, relative,
  99                                       (void *) (l_addr + relative->r_offset));
 100
 101 #ifdef RTLD_BOOTSTRAP
 102       /* The dynamic linker always uses versioning.  */
 103       assert (map->l_info[VERSYMIDX (DT_VERSYM)] != NULL);
 104 #else
 105       if (map->l_info[VERSYMIDX (DT_VERSYM)])
 106 #endif
 107         {
 108           const ElfW(Half) *const version =
 109             (const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]);
 110
 111           for (; r < end; ++r)
 112             {
 113               ElfW(Half) ndx = version[ELFW(R_SYM) (r->r_info)];
 114               elf_machine_rel (map, r, &symtab[ELFW(R_SYM) (r->r_info)],
 115                                &map->l_versions[ndx],
 116                                (void *) (l_addr + r->r_offset));
 117             }
 118         }
 119 #ifndef RTLD_BOOTSTRAP
 120       else
 121         for (; r < end; ++r)
 122           elf_machine_rel (map, r, &symtab[ELFW(R_SYM) (r->r_info)], NULL,
 123                            (void *) (l_addr + r->r_offset));
 124 #endif
 125     }
 126 }
 127
 128 #undef elf_dynamic_do_rel
 129 #undef Rel
 130 #undef elf_machine_rel
 131 #undef elf_machine_rel_relative
 132 #undef RELCOUNT_IDX