sysdeps/generic/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  Stub version.
   2    Copyright (C) 1995, 1996, 1997, 1999, 2000, 2001, 2005
   3    Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #define ELF_MACHINE_NAME "stub"
  22
  23 #include <string.h>
  24 #include <link.h>
  25
  26
  27 /* Return nonzero iff ELF header is compatible with the running host.  */
  28 static inline int
  29 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
  30 {
  31   switch (ehdr->e_machine)
  32     {
  33     default:
  34       return 0;
  35     }
  36 }
  37
  38
  39 /* Return the link-time address of _DYNAMIC.  */
  40 static inline Elf32_Addr
  41 elf_machine_dynamic (void)
  42 {
  43 #error "Damn, no _DYNAMIC"
  44 }
  45
  46
  47 /* Return the run-time load address of the shared object.  */
  48 static inline Elf32_Addr
  49 elf_machine_load_address (void)
  50 {
  51 #error "Where am I?"
  52 }
  53
  54 /* Fixup a PLT entry to bounce directly to the function at VALUE.  */
  55
  56 static inline Elf32_Addr
  57 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
  58                        const Elf32_Rel *reloc,
  59                        Elf32_Addr *reloc_addr, Elf32_Addr value)
  60 {
  61   return *reloc_addr = value;
  62 }
  63
  64 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
  65    LOADADDR is the load address of the object; INFO is an array indexed
  66    by DT_* of the .dynamic section info.  */
  67
  68 auto inline void
  69 __attribute__ ((always_inline))
  70 elf_machine_rel (Elf32_Addr loadaddr, Elf32_Dyn *info[DT_NUM],
  71                  const Elf32_Rel *reloc, const Elf32_Sym *sym,
  72                  Elf32_Addr (*resolve) (const Elf32_Sym **ref,
  73                                         Elf32_Addr reloc_addr,
  74                                         int noplt))
  75 {
  76   Elf32_Addr *const reloc_addr = (Elf32_Addr *) reloc->r_offset;
  77   Elf32_Addr loadbase;
  78
  79   switch (ELF32_R_TYPE (reloc->r_info))
  80     {
  81     case R_MACHINE_COPY:
  82       loadbase = (*resolve) (&sym, (Elf32_Addr) reloc_addr, 0);
  83       memcpy (reloc_addr, (void *) (loadbase + sym->st_value), sym->st_size);
  84       break;
  85     default:
  86       _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 0);
  87       break;
  88     }
  89 }
  90
  91
  92 auto inline Elf32_Addr
  93 __attribute__ ((always_inline))
  94 elf_machine_rela (Elf32_Addr loadaddr, Elf32_Dyn *info[DT_NUM],
  95                   const Elf32_Rel *reloc, const Elf32_Sym *sym,
  96                   Elf32_Addr (*resolve) (const Elf32_Sym **ref,
  97                                          Elf32_Addr reloc_addr,
  98                                          int noplt))
  99 {
 100   _dl_signal_error (0, "Elf32_Rela relocation requested -- unused on "
 101                     NULL, ELF_MACHINE_NAME);
 102 }
 103
 104
 105 /* Set up the loaded object described by L so its unrelocated PLT
 106    entries will jump to the on-demand fixup code in dl-runtime.c.  */
 107
 108 static inline int
 109 elf_machine_runtime_setup (struct link_map *l, int lazy)
 110 {
 111   extern void _dl_runtime_resolve (Elf32_Word);
 112
 113   if (lazy)
 114     {
 115       /* The GOT entries for functions in the PLT have not yet been filled
 116          in.  Their initial contents will arrange when called to push an
 117          offset into the .rel.plt section, push _GLOBAL_OFFSET_TABLE_[1],
 118          and then jump to _GLOBAL_OFFSET_TABLE[2].  */
 119       Elf32_Addr *got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
 120       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
 121
 122       /* This function will get called to fix up the GOT entry indicated by
 123          the offset on the stack, and then jump to the resolved address.  */
 124       got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 125     }
 126
 127   return lazy;
 128 }
 129
 130
 131 /* Initial entry point code for the dynamic linker.
 132    The C function `_dl_start' is the real entry point;
 133    its return value is the user program's entry point.  */
 134
 135 #define RTLD_START #error need some startup code