sysdeps/m68k/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  m68k version.
   2    Copyright (C) 1996-2001, 2002, 2003, 2004, 2005 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 #ifndef dl_machine_h
  21 #define dl_machine_h
  22
  23 #define ELF_MACHINE_NAME "m68k"
  24
  25 #include <sys/param.h>
  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   return ehdr->e_machine == EM_68K;
  32 }
  33
  34
  35 /* Return the link-time address of _DYNAMIC.  Conveniently, this is the
  36    first element of the GOT.  This must be inlined in a function which
  37    uses global data.  */
  38 static inline Elf32_Addr
  39 elf_machine_dynamic (void)
  40 {
  41   register Elf32_Addr *got asm ("%a5");
  42   return *got;
  43 }
  44
  45
  46 /* Return the run-time load address of the shared object.  */
  47 static inline Elf32_Addr
  48 elf_machine_load_address (void)
  49 {
  50   Elf32_Addr addr;
  51   asm ("lea _dl_start(%%pc), %0\n\t"
  52        "sub.l _dl_start@GOT.w(%%a5), %0"
  53        : "=a" (addr));
  54   return addr;
  55 }
  56
  57
  58 /* Set up the loaded object described by L so its unrelocated PLT
  59    entries will jump to the on-demand fixup code in dl-runtime.c.  */
  60
  61 static inline int __attribute__ ((always_inline))
  62 elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
  63 {
  64   Elf32_Addr *got;
  65   extern void _dl_runtime_resolve (Elf32_Word);
  66   extern void _dl_runtime_profile (Elf32_Word);
  67
  68   if (l->l_info[DT_JMPREL] && lazy)
  69     {
  70       /* The GOT entries for functions in the PLT have not yet been
  71          filled in.  Their initial contents will arrange when called
  72          to push an offset into the .rela.plt section, push
  73          _GLOBAL_OFFSET_TABLE_[1], and then jump to
  74          _GLOBAL_OFFSET_TABLE_[2].  */
  75       got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
  76       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
  77
  78       /* The got[2] entry contains the address of a function which gets
  79          called to get the address of a so far unresolved function and
  80          jump to it.  The profiling extension of the dynamic linker allows
  81          to intercept the calls to collect information.  In this case we
  82          don't store the address in the GOT so that all future calls also
  83          end in this function.  */
  84       if (profile)
  85         {
  86           got[2] = (Elf32_Addr) &_dl_runtime_profile;
  87
  88           if (GLRO(dl_profile) != NULL
  89               && _dl_name_match_p (GLRO(dl_profile), l))
  90             {
  91               /* This is the object we are looking for.  Say that we really
  92                  want profiling and the timers are started.  */
  93               GL(dl_profile_map) = l;
  94             }
  95         }
  96       else
  97         /* This function will get called to fix up the GOT entry indicated by
  98            the offset on the stack, and then jump to the resolved address.  */
  99         got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 100     }
 101
 102   return lazy;
 103 }
 104
 105 #define ELF_MACHINE_RUNTIME_FIXUP_ARGS long int save_a0, long int save_a1
 106
 107
 108 /* Mask identifying addresses reserved for the user program,
 109    where the dynamic linker should not map anything.  */
 110 #define ELF_MACHINE_USER_ADDRESS_MASK   0x80000000UL
 111
 112 /* Initial entry point code for the dynamic linker.
 113    The C function `_dl_start' is the real entry point;
 114    its return value is the user program's entry point.  */
 115
 116 #define RTLD_START asm ("\
 117         .text\n\
 118         .globl _start\n\
 119         .type _start,@function\n\
 120 _start:\n\
 121         move.l %sp, -(%sp)\n\
 122         jbsr _dl_start\n\
 123         addq.l #4, %sp\n\
 124         /* FALLTHRU */\n\
 125 \n\
 126         .globl _dl_start_user\n\
 127         .type _dl_start_user,@function\n\
 128 _dl_start_user:\n\
 129         | Save the user entry point address in %a4.\n\
 130         move.l %d0, %a4\n\
 131         | See if we were run as a command with the executable file\n\
 132         | name as an extra leading argument.\n\
 133         move.l _dl_skip_args(%pc), %d0\n\
 134         | Pop the original argument count\n\
 135         move.l (%sp)+, %d1\n\
 136         | Subtract _dl_skip_args from it.\n\
 137         sub.l %d0, %d1\n\
 138         | Adjust the stack pointer to skip _dl_skip_args words.\n\
 139         lea (%sp, %d0*4), %sp\n\
 140         | Push back the modified argument count.\n\
 141         move.l %d1, -(%sp)\n\
 142         # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
 143         pea 8(%sp, %d1*4)\n\
 144         pea 8(%sp)\n\
 145         move.l %d1, -(%sp)\n\
 146         move.l _rtld_local(%pc), -(%sp)\n\
 147         jbsr _dl_init_internal@PLTPC\n\
 148         addq.l #8, %sp\n\
 149         addq.l #8, %sp\n\
 150         | Pass our finalizer function to the user in %a1.\n\
 151         lea _dl_fini(%pc), %a1\n\
 152         | Initialize %fp with the stack pointer.\n\
 153         move.l %sp, %fp\n\
 154         | Jump to the user's entry point.\n\
 155         jmp (%a4)\n\
 156         .size _dl_start_user, . - _dl_start_user\n\
 157         .previous");
 158
 159 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so
 160    PLT entries should not be allowed to define the value.
 161    ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one
 162    of the main executable's symbols, as for a COPY reloc.  */
 163 #define elf_machine_type_class(type) \
 164   ((((type) == R_68K_JMP_SLOT) * ELF_RTYPE_CLASS_PLT)   \
 165    | (((type) == R_68K_COPY) * ELF_RTYPE_CLASS_COPY))
 166
 167 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 168 #define ELF_MACHINE_JMP_SLOT    R_68K_JMP_SLOT
 169
 170 /* The m68k never uses Elf32_Rel relocations.  */
 171 #define ELF_MACHINE_NO_REL 1
 172
 173 static inline Elf32_Addr
 174 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 175                        const Elf32_Rela *reloc,
 176                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 177 {
 178   return *reloc_addr = value;
 179 }
 180
 181 /* Return the final value of a plt relocation.  On the m68k the JMP_SLOT
 182    relocation ignores the addend.  */
 183 static inline Elf32_Addr
 184 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 185                        Elf32_Addr value)
 186 {
 187   return value;
 188 }
 189
 190 /* Names of the architecture-specific auditing callback functions.  */
 191 #define ARCH_LA_PLTENTER m68k_gnu_pltenter
 192 #define ARCH_LA_PLTEXIT m68k_gnu_pltexit
 193
 194 #endif /* !dl_machine_h */
 195
 196 #ifdef RESOLVE_MAP
 197
 198 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 199    MAP is the object containing the reloc.  */
 200
 201 auto inline void __attribute__ ((unused, always_inline))
 202 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 203                   const Elf32_Sym *sym, const struct r_found_version *version,
 204                   void *const reloc_addr_arg)
 205 {
 206   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 207   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 208
 209   if (__builtin_expect (r_type == R_68K_RELATIVE, 0))
 210     *reloc_addr = map->l_addr + reloc->r_addend;
 211   else
 212     {
 213       const Elf32_Sym *const refsym = sym;
 214       struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
 215       Elf32_Addr value = sym == NULL ? 0 : sym_map->l_addr + sym->st_value;
 216
 217       switch (r_type)
 218         {
 219         case R_68K_COPY:
 220           if (sym == NULL)
 221             /* This can happen in trace mode if an object could not be
 222                found.  */
 223             break;
 224           if (sym->st_size > refsym->st_size
 225               || (sym->st_size < refsym->st_size && GLRO(dl_verbose)))
 226             {
 227               const char *strtab;
 228
 229               strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
 230               _dl_error_printf ("\
 231 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 232                                 rtld_progname ?: "<program name unknown>",
 233                                 strtab + refsym->st_name);
 234             }
 235           memcpy (reloc_addr_arg, (void *) value,
 236                   MIN (sym->st_size, refsym->st_size));
 237           break;
 238         case R_68K_GLOB_DAT:
 239         case R_68K_JMP_SLOT:
 240           *reloc_addr = value;
 241           break;
 242         case R_68K_8:
 243           *(char *) reloc_addr = value + reloc->r_addend;
 244           break;
 245         case R_68K_16:
 246           *(short *) reloc_addr = value + reloc->r_addend;
 247           break;
 248         case R_68K_32:
 249           *reloc_addr = value + reloc->r_addend;
 250           break;
 251         case R_68K_PC8:
 252           *(char *) reloc_addr
 253             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 254           break;
 255         case R_68K_PC16:
 256           *(short *) reloc_addr
 257             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 258           break;
 259         case R_68K_PC32:
 260           *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 261           break;
 262         case R_68K_NONE:                /* Alright, Wilbur.  */
 263           break;
 264         default:
 265           _dl_reloc_bad_type (map, r_type, 0);
 266           break;
 267         }
 268     }
 269 }
 270
 271 auto inline void __attribute__ ((unused, always_inline))
 272 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
 273                            void *const reloc_addr_arg)
 274 {
 275   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 276   *reloc_addr = l_addr + reloc->r_addend;
 277 }
 278
 279 auto inline void __attribute__ ((unused, always_inline))
 280 elf_machine_lazy_rel (struct link_map *map,
 281                       Elf32_Addr l_addr, const Elf32_Rela *reloc)
 282 {
 283   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 284   if (ELF32_R_TYPE (reloc->r_info) == R_68K_JMP_SLOT)
 285     *reloc_addr += l_addr;
 286   else
 287     _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 1);
 288 }
 289
 290 #endif /* RESOLVE_MAP */