sysdeps/m68k/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  m68k version.
   2    Copyright (C) 1996-2001, 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 #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
  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 (_dl_name_match_p (GL(dl_profile), l))
  89             {
  90               /* This is the object we are looking for.  Say that we really
  91                  want profiling and the timers are started.  */
  92               GL(dl_profile_map) = l;
  93             }
  94         }
  95       else
  96         /* This function will get called to fix up the GOT entry indicated by
  97            the offset on the stack, and then jump to the resolved address.  */
  98         got[2] = (Elf32_Addr) &_dl_runtime_resolve;
  99     }
 100
 101   return lazy;
 102 }
 103
 104 /* This code is used in dl-runtime.c to call the `fixup' function
 105    and then redirect to the address it returns.  */
 106 #define TRAMPOLINE_TEMPLATE(tramp_name, fixup_name) \
 107 "| Trampoline for " #fixup_name "\n\
 108         .globl " #tramp_name "\n\
 109         .type " #tramp_name ", @function\n\
 110 " #tramp_name ":\n\
 111         | Save %a0 (struct return address) and %a1.\n\
 112         move.l %a0, -(%sp)\n\
 113         move.l %a1, -(%sp)\n\
 114         | Call the real address resolver.\n\
 115         jbsr " #fixup_name "\n\
 116         | Restore register %a0 and %a1.\n\
 117         move.l (%sp)+, %a1\n\
 118         move.l (%sp)+, %a0\n\
 119         | Pop parameters\n\
 120         addq.l #8, %sp\n\
 121         | Call real function.\n\
 122         jmp (%d0)\n\
 123         .size " #tramp_name ", . - " #tramp_name "\n"
 124 #ifndef PROF
 125 #define ELF_MACHINE_RUNTIME_TRAMPOLINE \
 126 asm (TRAMPOLINE_TEMPLATE (_dl_runtime_resolve, fixup) \
 127      TRAMPOLINE_TEMPLATE (_dl_runtime_profile, profile_fixup));
 128 #else
 129 #define ELF_MACHINE_RUNTIME_TRAMPOLINE \
 130 asm (TRAMPOLINE_TEMPLATE (_dl_runtime_resolve, fixup) \
 131      ".globl _dl_runtime_profile\n" \
 132      ".set _dl_runtime_profile, _dl_runtime_resolve");
 133 #endif
 134 #define ELF_MACHINE_RUNTIME_FIXUP_ARGS long int save_a0, long int save_a1
 135
 136
 137 /* Mask identifying addresses reserved for the user program,
 138    where the dynamic linker should not map anything.  */
 139 #define ELF_MACHINE_USER_ADDRESS_MASK   0x80000000UL
 140
 141 /* Initial entry point code for the dynamic linker.
 142    The C function `_dl_start' is the real entry point;
 143    its return value is the user program's entry point.  */
 144
 145 #define RTLD_START asm ("\
 146         .text\n\
 147         .globl _start\n\
 148         .type _start,@function\n\
 149 _start:\n\
 150         move.l %sp, -(%sp)\n\
 151         jbsr _dl_start\n\
 152         addq.l #4, %sp\n\
 153         /* FALLTHRU */\n\
 154 \n\
 155         .globl _dl_start_user\n\
 156         .type _dl_start_user,@function\n\
 157 _dl_start_user:\n\
 158         | Save the user entry point address in %a4.\n\
 159         move.l %d0, %a4\n\
 160         | Point %a5 at the GOT.\n\
 161         lea _GLOBAL_OFFSET_TABLE_@GOTPC(%pc), %a5\n\
 162         | Remember the highest stack address.\n\
 163         move.l %sp, ([__libc_stack_end@GOT.w, %a5])\n\
 164         | See if we were run as a command with the executable file\n\
 165         | name as an extra leading argument.\n\
 166         move.l ([_dl_skip_args@GOT.w, %a5]), %d0\n\
 167         | Pop the original argument count\n\
 168         move.l (%sp)+, %d1\n\
 169         | Subtract _dl_skip_args from it.\n\
 170         sub.l %d0, %d1\n\
 171         | Adjust the stack pointer to skip _dl_skip_args words.\n\
 172         lea (%sp, %d0*4), %sp\n\
 173         | Push back the modified argument count.\n\
 174         move.l %d1, -(%sp)\n\
 175         # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
 176         pea 8(%sp, %d1*4)\n\
 177         pea 8(%sp)\n\
 178         move.l %d1, -(%sp)\n\
 179         move.l ([_rtld_global@GOT.w, %a5]), -(%sp)\n\
 180         jbsr _dl_init_internal@PLTPC\n\
 181         addq.l #8, %sp\n\
 182         addq.l #8, %sp\n\
 183         | Pass our finalizer function to the user in %a1.\n\
 184         move.l _dl_fini@GOT.w(%a5), %a1\n\
 185         | Initialize %fp with the stack pointer.\n\
 186         move.l %sp, %fp\n\
 187         | Jump to the user's entry point.\n\
 188         jmp (%a4)\n\
 189         .size _dl_start_user, . - _dl_start_user\n\
 190         .previous");
 191
 192 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so
 193    PLT entries should not be allowed to define the value.
 194    ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one
 195    of the main executable's symbols, as for a COPY reloc.  */
 196 #define elf_machine_type_class(type) \
 197   ((((type) == R_68K_JMP_SLOT) * ELF_RTYPE_CLASS_PLT)   \
 198    | (((type) == R_68K_COPY) * ELF_RTYPE_CLASS_COPY))
 199
 200 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 201 #define ELF_MACHINE_JMP_SLOT    R_68K_JMP_SLOT
 202
 203 /* The m68k never uses Elf32_Rel relocations.  */
 204 #define ELF_MACHINE_NO_REL 1
 205
 206 static inline Elf32_Addr
 207 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 208                        const Elf32_Rela *reloc,
 209                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 210 {
 211   return *reloc_addr = value;
 212 }
 213
 214 /* Return the final value of a plt relocation.  On the m68k the JMP_SLOT
 215    relocation ignores the addend.  */
 216 static inline Elf32_Addr
 217 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 218                        Elf32_Addr value)
 219 {
 220   return value;
 221 }
 222
 223 #endif /* !dl_machine_h */
 224
 225 #ifdef RESOLVE
 226
 227 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 228    MAP is the object containing the reloc.  */
 229
 230 static inline void
 231 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 232                   const Elf32_Sym *sym, const struct r_found_version *version,
 233                   Elf32_Addr *const reloc_addr)
 234 {
 235   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 236
 237   if (__builtin_expect (r_type == R_68K_RELATIVE, 0))
 238     *reloc_addr = map->l_addr + reloc->r_addend;
 239   else
 240     {
 241       const Elf32_Sym *const refsym = sym;
 242       Elf32_Addr value = RESOLVE (&sym, version, r_type);
 243       if (sym)
 244         value += sym->st_value;
 245
 246       switch (r_type)
 247         {
 248         case R_68K_COPY:
 249           if (sym == NULL)
 250             /* This can happen in trace mode if an object could not be
 251                found.  */
 252             break;
 253           if (sym->st_size > refsym->st_size
 254               || (sym->st_size < refsym->st_size && GL(dl_verbose)))
 255             {
 256               extern char **_dl_argv;
 257               const char *strtab;
 258
 259               strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
 260               _dl_error_printf ("\
 261 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 262                                 _dl_argv[0] ?: "<program name unknown>",
 263                                 strtab + refsym->st_name);
 264             }
 265           memcpy (reloc_addr, (void *) value, MIN (sym->st_size,
 266                                                    refsym->st_size));
 267           break;
 268         case R_68K_GLOB_DAT:
 269         case R_68K_JMP_SLOT:
 270           *reloc_addr = value;
 271           break;
 272         case R_68K_8:
 273           *(char *) reloc_addr = value + reloc->r_addend;
 274           break;
 275         case R_68K_16:
 276           *(short *) reloc_addr = value + reloc->r_addend;
 277           break;
 278         case R_68K_32:
 279           *reloc_addr = value + reloc->r_addend;
 280           break;
 281         case R_68K_PC8:
 282           *(char *) reloc_addr
 283             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 284           break;
 285         case R_68K_PC16:
 286           *(short *) reloc_addr
 287             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 288           break;
 289         case R_68K_PC32:
 290           *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 291           break;
 292         case R_68K_NONE:                /* Alright, Wilbur.  */
 293           break;
 294         default:
 295           _dl_reloc_bad_type (map, r_type, 0);
 296           break;
 297         }
 298     }
 299 }
 300
 301 static inline void
 302 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
 303                            Elf32_Addr *const reloc_addr)
 304 {
 305   *reloc_addr = l_addr + reloc->r_addend;
 306 }
 307
 308 static inline void
 309 elf_machine_lazy_rel (struct link_map *map,
 310                       Elf32_Addr l_addr, const Elf32_Rela *reloc)
 311 {
 312   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 313   if (ELF32_R_TYPE (reloc->r_info) == R_68K_JMP_SLOT)
 314     *reloc_addr += l_addr;
 315   else
 316     _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 1);
 317 }
 318
 319 #endif /* RESOLVE */