elf/do-rel.h

   1 /* Do relocations for ELF dynamic linking.
   2    Copyright (C) 1995-2003, 2004 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 DO_ELF_MACHINE_REL_RELATIVE
  34 # define DO_ELF_MACHINE_REL_RELATIVE(map, l_addr, relative) \
  35   elf_machine_rel_relative (l_addr, relative,                                 \
  36                             (void *) (l_addr + relative->r_offset))
  37 #endif
  38
  39 #ifndef VERSYMIDX
  40 # define VERSYMIDX(sym) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (sym))
  41 #endif
  42 #ifndef VALIDX
  43 # define VALIDX(tag) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM \
  44                       + DT_EXTRANUM + DT_VALTAGIDX (tag))
  45 #endif
  46
  47 /* Perform the relocations in MAP on the running program image as specified
  48    by RELTAG, SZTAG.  If LAZY is nonzero, this is the first pass on PLT
  49    relocations; they should be set up to call _dl_runtime_resolve, rather
  50    than fully resolved now.  */
  51
  52 auto inline void __attribute__ ((always_inline))
  53 elf_dynamic_do_rel (struct link_map *map,
  54                     ElfW(Addr) reladdr, ElfW(Addr) relsize,
  55                     int lazy)
  56 {
  57   const ElfW(Rel) *r = (const void *) reladdr;
  58   const ElfW(Rel) *end = (const void *) (reladdr + relsize);
  59   ElfW(Addr) l_addr = map->l_addr;
  60
  61 #if (!defined DO_RELA || !defined ELF_MACHINE_PLT_REL) && !defined RTLD_BOOTSTRAP
  62   /* We never bind lazily during ld.so bootstrap.  Unfortunately gcc is
  63      not clever enough to see through all the function calls to realize
  64      that.  */
  65   if (lazy)
  66     {
  67       /* Doing lazy PLT relocations; they need very little info.  */
  68       for (; r < end; ++r)
  69         elf_machine_lazy_rel (map, l_addr, r);
  70     }
  71   else
  72 #endif
  73     {
  74       const ElfW(Sym) *const symtab =
  75         (const void *) D_PTR (map, l_info[DT_SYMTAB]);
  76       ElfW(Word) nrelative = (map->l_info[RELCOUNT_IDX] == NULL
  77                               ? 0 : map->l_info[RELCOUNT_IDX]->d_un.d_val);
  78       const ElfW(Rel) *relative = r;
  79       r = r + MIN (nrelative, relsize / sizeof (ElfW(Rel)));
  80
  81 #ifndef RTLD_BOOTSTRAP
  82       /* This is defined in rtld.c, but nowhere in the static libc.a; make
  83          the reference weak so static programs can still link.  This
  84          declaration cannot be done when compiling rtld.c (i.e. #ifdef
  85          RTLD_BOOTSTRAP) because rtld.c contains the common defn for
  86          _dl_rtld_map, which is incompatible with a weak decl in the same
  87          file.  */
  88 # ifndef SHARED
  89       weak_extern (GL(dl_rtld_map));
  90 # endif
  91       if (map != &GL(dl_rtld_map)) /* Already done in rtld itself.  */
  92 # if !defined DO_RELA || defined ELF_MACHINE_REL_RELATIVE
  93         /* Rela platforms get the offset from r_addend and this must
  94            be copied in the relocation address.  Therefore we can skip
  95            the relative relocations only if this is for rel
  96            relocations or rela relocations if they are computed as
  97            memory_loc += l_addr...  */
  98         if (l_addr != 0)
  99 # else
 100         /* ...or we know the object has been prelinked.  */
 101         if (l_addr != 0 || ! map->l_info[VALIDX(DT_GNU_PRELINKED)])
 102 # endif
 103 #endif
 104           for (; relative < r; ++relative)
 105             DO_ELF_MACHINE_REL_RELATIVE (map, l_addr, relative);
 106
 107 #ifdef RTLD_BOOTSTRAP
 108       /* The dynamic linker always uses versioning.  */
 109       assert (map->l_info[VERSYMIDX (DT_VERSYM)] != NULL);
 110 #else
 111       if (map->l_info[VERSYMIDX (DT_VERSYM)])
 112 #endif
 113         {
 114           const ElfW(Half) *const version =
 115             (const void *) D_PTR (map, l_info[VERSYMIDX (DT_VERSYM)]);
 116
 117           for (; r < end; ++r)
 118             {
 119               ElfW(Half) ndx = version[ELFW(R_SYM) (r->r_info)] & 0x7fff;
 120               elf_machine_rel (map, r, &symtab[ELFW(R_SYM) (r->r_info)],
 121                                &map->l_versions[ndx],
 122                                (void *) (l_addr + r->r_offset));
 123             }
 124         }
 125 #ifndef RTLD_BOOTSTRAP
 126       else
 127         for (; r < end; ++r)
 128           elf_machine_rel (map, r, &symtab[ELFW(R_SYM) (r->r_info)], NULL,
 129                            (void *) (l_addr + r->r_offset));
 130 #endif
 131     }
 132 }
 133
 134 #undef elf_dynamic_do_rel
 135 #undef Rel
 136 #undef elf_machine_rel
 137 #undef elf_machine_rel_relative
 138 #undef DO_ELF_MACHINE_REL_RELATIVE
 139 #undef RELCOUNT_IDX