elf/dynamic-link.h

   1 /* Inline functions for 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 #include <elf.h>
  21 #include <dl-machine.h>
  22 #include <assert.h>
  23
  24 #ifndef VERSYMIDX
  25 # define VERSYMIDX(sym) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (sym))
  26 #endif
  27
  28
  29 /* Read the dynamic section at DYN and fill in INFO with indices DT_*.  */
  30
  31 static inline void __attribute__ ((unused))
  32 elf_get_dynamic_info (struct link_map *l)
  33 {
  34   ElfW(Dyn) *dyn = l->l_ld;
  35   ElfW(Dyn) **info;
  36
  37 #ifndef RTLD_BOOTSTRAP
  38   if (dyn == NULL)
  39     return;
  40 #endif
  41
  42   info = l->l_info;
  43
  44   while (dyn->d_tag != DT_NULL)
  45     {
  46       if (dyn->d_tag < DT_NUM)
  47         info[dyn->d_tag] = dyn;
  48       else if (dyn->d_tag >= DT_LOPROC &&
  49                dyn->d_tag < DT_LOPROC + DT_THISPROCNUM)
  50         info[dyn->d_tag - DT_LOPROC + DT_NUM] = dyn;
  51       else if ((Elf32_Word) DT_VERSIONTAGIDX (dyn->d_tag) < DT_VERSIONTAGNUM)
  52         info[VERSYMIDX (dyn->d_tag)] = dyn;
  53       else if ((Elf32_Word) DT_EXTRATAGIDX (dyn->d_tag) < DT_EXTRANUM)
  54         info[DT_EXTRATAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM
  55              + DT_VERSIONTAGNUM] = dyn;
  56       else if ((Elf32_Word) DT_VALTAGIDX (dyn->d_tag) < DT_VALNUM)
  57         info[DT_VALTAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM
  58              + DT_VERSIONTAGNUM + DT_EXTRANUM] = dyn;
  59       else if ((Elf32_Word) DT_ADDRTAGIDX (dyn->d_tag) < DT_ADDRNUM)
  60         info[DT_ADDRTAGIDX (dyn->d_tag) + DT_NUM + DT_THISPROCNUM
  61              + DT_VERSIONTAGNUM + DT_EXTRANUM + DT_VALNUM] = dyn;
  62       else
  63         assert (! "bad dynamic tag");
  64       ++dyn;
  65     }
  66 #ifndef DL_RO_DYN_SECTION
  67   /* Don't adjust .dynamic unnecessarily.  */
  68   if (l->l_addr != 0)
  69     {
  70       ElfW(Addr) l_addr = l->l_addr;
  71
  72       if (info[DT_PLTGOT] != NULL)
  73         info[DT_PLTGOT]->d_un.d_ptr += l_addr;
  74       if (info[DT_STRTAB] != NULL)
  75         info[DT_STRTAB]->d_un.d_ptr += l_addr;
  76       if (info[DT_SYMTAB] != NULL)
  77         info[DT_SYMTAB]->d_un.d_ptr += l_addr;
  78 # if ! ELF_MACHINE_NO_RELA
  79       if (info[DT_RELA] != NULL)
  80         info[DT_RELA]->d_un.d_ptr += l_addr;
  81 # endif
  82 # if ! ELF_MACHINE_NO_REL
  83       if (info[DT_REL] != NULL)
  84         info[DT_REL]->d_un.d_ptr += l_addr;
  85 # endif
  86       if (info[DT_JMPREL] != NULL)
  87         info[DT_JMPREL]->d_un.d_ptr += l_addr;
  88       if (info[VERSYMIDX (DT_VERSYM)] != NULL)
  89         info[VERSYMIDX (DT_VERSYM)]->d_un.d_ptr += l_addr;
  90     }
  91 #endif
  92   if (info[DT_PLTREL] != NULL)
  93     {
  94 #if ELF_MACHINE_NO_RELA
  95       assert (info[DT_PLTREL]->d_un.d_val == DT_REL);
  96 #elif ELF_MACHINE_NO_REL
  97       assert (info[DT_PLTREL]->d_un.d_val == DT_RELA);
  98 #else
  99       assert (info[DT_PLTREL]->d_un.d_val == DT_REL
 100               || info[DT_PLTREL]->d_un.d_val == DT_RELA);
 101 #endif
 102     }
 103 #if ! ELF_MACHINE_NO_RELA
 104   if (info[DT_RELA] != NULL)
 105     assert (info[DT_RELAENT]->d_un.d_val == sizeof (ElfW(Rela)));
 106 # endif
 107 # if ! ELF_MACHINE_NO_REL
 108   if (info[DT_REL] != NULL)
 109     assert (info[DT_RELENT]->d_un.d_val == sizeof (ElfW(Rel)));
 110 #endif
 111   if (info[DT_FLAGS] != NULL)
 112     {
 113       /* Flags are used.  Translate to the old form where available.
 114          Since these l_info entries are only tested for NULL pointers it
 115          is ok if they point to the DT_FLAGS entry.  */
 116       l->l_flags = info[DT_FLAGS]->d_un.d_val;
 117 #ifdef RTLD_BOOTSTRAP
 118       /* These three flags must not be set for ld.so.  */
 119       assert ((l->l_flags & (DF_SYMBOLIC | DF_TEXTREL | DF_BIND_NOW)) == 0);
 120 #else
 121       if (l->l_flags & DF_SYMBOLIC)
 122         info[DT_SYMBOLIC] = info[DT_FLAGS];
 123       if (l->l_flags & DF_TEXTREL)
 124         info[DT_TEXTREL] = info[DT_FLAGS];
 125       if (l->l_flags & DF_BIND_NOW)
 126         info[DT_BIND_NOW] = info[DT_FLAGS];
 127 #endif
 128     }
 129   if (info[VERSYMIDX (DT_FLAGS_1)] != NULL)
 130     l->l_flags_1 = info[VERSYMIDX (DT_FLAGS_1)]->d_un.d_val;
 131 #ifdef RTLD_BOOTSTRAP
 132   /* The dynamic linker should have none of these set.  */
 133   assert (info[DT_RUNPATH] == NULL);
 134   assert (info[DT_RPATH] == NULL);
 135 #else
 136   if (info[DT_RUNPATH] != NULL)
 137     /* If both RUNPATH and RPATH are given, the latter is ignored.  */
 138     info[DT_RPATH] = NULL;
 139 #endif
 140 }
 141
 142 #ifdef RESOLVE
 143
 144 # ifdef RTLD_BOOTSTRAP
 145 #  define ELF_DURING_STARTUP (1)
 146 # else
 147 #  define ELF_DURING_STARTUP (0)
 148 # endif
 149
 150 /* Get the definitions of `elf_dynamic_do_rel' and `elf_dynamic_do_rela'.
 151    These functions are almost identical, so we use cpp magic to avoid
 152    duplicating their code.  It cannot be done in a more general function
 153    because we must be able to completely inline.  */
 154
 155 /* On some machines, notably SPARC, DT_REL* includes DT_JMPREL in its
 156    range.  Note that according to the ELF spec, this is completely legal!
 157    But conditionally define things so that on machines we know this will
 158    not happen we do something more optimal.  */
 159
 160 # ifdef ELF_MACHINE_PLTREL_OVERLAP
 161 #  define _ELF_DYNAMIC_DO_RELOC(RELOC, reloc, map, do_lazy, test_rel) \
 162   do {                                                                        \
 163     struct { ElfW(Addr) start, size; int lazy; } ranges[3];                   \
 164     int ranges_index;                                                         \
 165                                                                               \
 166     ranges[0].lazy = ranges[2].lazy = 0;                                      \
 167     ranges[1].lazy = 1;                                                       \
 168     ranges[0].size = ranges[1].size = ranges[2].size = 0;                     \
 169                                                                               \
 170     if ((map)->l_info[DT_##RELOC])                                            \
 171       {                                                                       \
 172         ranges[0].start = D_PTR ((map), l_info[DT_##RELOC]);                  \
 173         ranges[0].size = (map)->l_info[DT_##RELOC##SZ]->d_un.d_val;           \
 174       }                                                                       \
 175                                                                               \
 176     if ((do_lazy)                                                             \
 177         && (map)->l_info[DT_PLTREL]                                           \
 178         && (!test_rel || (map)->l_info[DT_PLTREL]->d_un.d_val == DT_##RELOC)) \
 179       {                                                                       \
 180         ranges[1].start = D_PTR ((map), l_info[DT_JMPREL]);                   \
 181         ranges[1].size = (map)->l_info[DT_PLTRELSZ]->d_un.d_val;              \
 182         ranges[2].start = ranges[1].start + ranges[1].size;                   \
 183         ranges[2].size = ranges[0].start + ranges[0].size - ranges[2].start;  \
 184         ranges[0].size = ranges[1].start - ranges[0].start;                   \
 185       }                                                                       \
 186                                                                               \
 187     for (ranges_index = 0; ranges_index < 3; ++ranges_index)                  \
 188       elf_dynamic_do_##reloc ((map),                                          \
 189                               ranges[ranges_index].start,                     \
 190                               ranges[ranges_index].size,                      \
 191                               ranges[ranges_index].lazy);                     \
 192   } while (0)
 193 # else
 194 #  define _ELF_DYNAMIC_DO_RELOC(RELOC, reloc, map, do_lazy, test_rel) \
 195   do {                                                                        \
 196     struct { ElfW(Addr) start, size; int lazy; } ranges[2];                   \
 197     ranges[0].lazy = 0;                                                       \
 198     ranges[0].size = ranges[1].size = 0;                                      \
 199     ranges[0].start = 0;                                                      \
 200                                                                               \
 201     if ((map)->l_info[DT_##RELOC])                                            \
 202       {                                                                       \
 203         ranges[0].start = D_PTR ((map), l_info[DT_##RELOC]);                  \
 204         ranges[0].size = (map)->l_info[DT_##RELOC##SZ]->d_un.d_val;           \
 205       }                                                                       \
 206     if ((map)->l_info[DT_PLTREL]                                              \
 207         && (!test_rel || (map)->l_info[DT_PLTREL]->d_un.d_val == DT_##RELOC)) \
 208       {                                                                       \
 209         ElfW(Addr) start = D_PTR ((map), l_info[DT_JMPREL]);                  \
 210                                                                               \
 211         if (! ELF_DURING_STARTUP                                              \
 212             && ((do_lazy)                                                     \
 213                 /* This test does not only detect whether the relocation      \
 214                    sections are in the right order, it also checks whether    \
 215                    there is a DT_REL/DT_RELA section.  */                     \
 216                 || ranges[0].start + ranges[0].size != start))                \
 217           {                                                                   \
 218             ranges[1].start = start;                                          \
 219             ranges[1].size = (map)->l_info[DT_PLTRELSZ]->d_un.d_val;          \
 220             ranges[1].lazy = (do_lazy);                                       \
 221           }                                                                   \
 222         else                                                                  \
 223           {                                                                   \
 224             /* Combine processing the sections.  */                           \
 225             assert (ranges[0].start + ranges[0].size == start);               \
 226             ranges[0].size += (map)->l_info[DT_PLTRELSZ]->d_un.d_val;         \
 227           }                                                                   \
 228       }                                                                       \
 229                                                                               \
 230     if (ELF_DURING_STARTUP)                                                   \
 231       elf_dynamic_do_##reloc ((map), ranges[0].start, ranges[0].size, 0);     \
 232     else                                                                      \
 233       {                                                                       \
 234         int ranges_index;                                                     \
 235         for (ranges_index = 0; ranges_index < 2; ++ranges_index)              \
 236           elf_dynamic_do_##reloc ((map),                                      \
 237                                   ranges[ranges_index].start,                 \
 238                                   ranges[ranges_index].size,                  \
 239                                   ranges[ranges_index].lazy);                 \
 240       }                                                                       \
 241   } while (0)
 242 # endif
 243
 244 # if ELF_MACHINE_NO_REL || ELF_MACHINE_NO_RELA
 245 #  define _ELF_CHECK_REL 0
 246 # else
 247 #  define _ELF_CHECK_REL 1
 248 # endif
 249
 250 # if ! ELF_MACHINE_NO_REL
 251 #  include "do-rel.h"
 252 #  define ELF_DYNAMIC_DO_REL(map, lazy) \
 253   _ELF_DYNAMIC_DO_RELOC (REL, rel, map, lazy, _ELF_CHECK_REL)
 254 # else
 255 #  define ELF_DYNAMIC_DO_REL(map, lazy) /* Nothing to do.  */
 256 # endif
 257
 258 # if ! ELF_MACHINE_NO_RELA
 259 #  define DO_RELA
 260 #  include "do-rel.h"
 261 #  define ELF_DYNAMIC_DO_RELA(map, lazy) \
 262   _ELF_DYNAMIC_DO_RELOC (RELA, rela, map, lazy, _ELF_CHECK_REL)
 263 # else
 264 #  define ELF_DYNAMIC_DO_RELA(map, lazy) /* Nothing to do.  */
 265 # endif
 266
 267 /* This can't just be an inline function because GCC is too dumb
 268    to inline functions containing inlines themselves.  */
 269 # define ELF_DYNAMIC_RELOCATE(map, lazy, consider_profile) \
 270   do {                                                                        \
 271     int edr_lazy = elf_machine_runtime_setup ((map), (lazy),                  \
 272                                               (consider_profile));            \
 273     ELF_DYNAMIC_DO_REL ((map), edr_lazy);                                     \
 274     ELF_DYNAMIC_DO_RELA ((map), edr_lazy);                                    \
 275   } while (0)
 276
 277 #endif