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 = r + MIN (nrelative, relsize / sizeof (ElfW(Rel)));
  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 # if !defined DO_RELA || defined ELF_MACHINE_REL_RELATIVE
  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 or rela relocations if they are computed as
  91            memory_loc += l_addr...  */
  92         if (l_addr != 0)
  93 # else
  94         /* ...or we know the object has been prelinked.  */
  95         if (l_addr != 0 || ! map->l_info[VALIDX(DT_GNU_PRELINKED)])
  96 # endif
  97 #endif
  98           for (; relative < r; ++relative)
  99             elf_machine_rel_relative (l_addr, relative,
 100                                       (void *) (l_addr + relative->r_offset));
 101
 102 #ifdef RTLD_BOOTSTRAP
 103       /* The dynamic linker always uses versioning.  */
 104       assert (map->l_info[VERSYMIDX (DT_VERSYM)] != NULL);
 105 #else
 106       if (map->l_info[VERSYMIDX (DT_VERSYM)])
 107 #endif
 108         {
 109           const ElfW(Half) *const version =
 110             (const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]);
 111
 112           for (; r < end; ++r)
 113             {
 114               ElfW(Half) ndx = version[ELFW(R_SYM) (r->r_info)];
 115               elf_machine_rel (map, r, &symtab[ELFW(R_SYM) (r->r_info)],
 116                                &map->l_versions[ndx],
 117                                (void *) (l_addr + r->r_offset));
 118             }
 119         }
 120 #ifndef RTLD_BOOTSTRAP
 121       else
 122         for (; r < end; ++r)
 123           elf_machine_rel (map, r, &symtab[ELFW(R_SYM) (r->r_info)], NULL,
 124                            (void *) (l_addr + r->r_offset));
 125 #endif
 126     }
 127 }
 128
 129 #undef elf_dynamic_do_rel
 130 #undef Rel
 131 #undef elf_machine_rel
 132 #undef elf_machine_rel_relative
 133 #undef RELCOUNT_IDX