sysdeps/m68k/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  m68k version.
   2    Copyright (C) 1996, 1997, 1998, 1999, 2000 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 Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If
  17    not, write to the Free Software Foundation, Inc.,
  18    59 Temple Place - Suite 330, Boston, MA 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 E_MACHINE is compatible with the running host.  */
  28 static inline int
  29 elf_machine_matches_host (Elf32_Half e_machine)
  30 {
  31   switch (e_machine)
  32     {
  33     case EM_68K:
  34       return 1;
  35     default:
  36       return 0;
  37     }
  38 }
  39
  40
  41 /* Return the link-time address of _DYNAMIC.  Conveniently, this is the
  42    first element of the GOT.  This must be inlined in a function which
  43    uses global data.  */
  44 static inline Elf32_Addr
  45 elf_machine_dynamic (void)
  46 {
  47   register Elf32_Addr *got asm ("%a5");
  48   return *got;
  49 }
  50
  51
  52 /* Return the run-time load address of the shared object.  */
  53 static inline Elf32_Addr
  54 elf_machine_load_address (void)
  55 {
  56   Elf32_Addr addr;
  57   asm ("lea _dl_start(%%pc), %0\n\t"
  58        "sub.l _dl_start@GOT.w(%%a5), %0"
  59        : "=a" (addr));
  60   return addr;
  61 }
  62
  63
  64 /* Set up the loaded object described by L so its unrelocated PLT
  65    entries will jump to the on-demand fixup code in dl-runtime.c.  */
  66
  67 static inline int
  68 elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
  69 {
  70   Elf32_Addr *got;
  71   extern void _dl_runtime_resolve (Elf32_Word);
  72   extern void _dl_runtime_profile (Elf32_Word);
  73
  74   if (l->l_info[DT_JMPREL] && lazy)
  75     {
  76       /* The GOT entries for functions in the PLT have not yet been
  77          filled in.  Their initial contents will arrange when called
  78          to push an offset into the .rela.plt section, push
  79          _GLOBAL_OFFSET_TABLE_[1], and then jump to
  80          _GLOBAL_OFFSET_TABLE_[2].  */
  81       got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
  82       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
  83
  84       /* The got[2] entry contains the address of a function which gets
  85          called to get the address of a so far unresolved function and
  86          jump to it.  The profiling extension of the dynamic linker allows
  87          to intercept the calls to collect information.  In this case we
  88          don't store the address in the GOT so that all future calls also
  89          end in this function.  */
  90       if (profile)
  91         {
  92           got[2] = (Elf32_Addr) &_dl_runtime_profile;
  93
  94           if (_dl_name_match_p (_dl_profile, l))
  95             {
  96               /* This is the object we are looking for.  Say that we really
  97                  want profiling and the timers are started.  */
  98               _dl_profile_map = l;
  99             }
 100         }
 101       else
 102         /* This function will get called to fix up the GOT entry indicated by
 103            the offset on the stack, and then jump to the resolved address.  */
 104         got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 105     }
 106
 107   return lazy;
 108 }
 109
 110 /* This code is used in dl-runtime.c to call the `fixup' function
 111    and then redirect to the address it returns.  */
 112 #define TRAMPOLINE_TEMPLATE(tramp_name, fixup_name) \
 113 "| Trampoline for " #fixup_name "
 114         .globl " #tramp_name "
 115         .type " #tramp_name ", @function
 116 " #tramp_name ":
 117         | Save %a0 (struct return address) and %a1.
 118         move.l %a0, -(%sp)
 119         move.l %a1, -(%sp)
 120         | Call the real address resolver.
 121         jbsr " #fixup_name "
 122         | Restore register %a0 and %a1.
 123         move.l (%sp)+, %a1
 124         move.l (%sp)+, %a0
 125         | Pop parameters
 126         addq.l #8, %sp
 127         | Call real function.
 128         jmp (%d0)
 129         .size " #tramp_name ", . - " #tramp_name "\n"
 130 #ifndef PROF
 131 #define ELF_MACHINE_RUNTIME_TRAMPOLINE \
 132 asm (TRAMPOLINE_TEMPLATE (_dl_runtime_resolve, fixup) \
 133      TRAMPOLINE_TEMPLATE (_dl_runtime_profile, profile_fixup));
 134 #else
 135 #define ELF_MACHINE_RUNTIME_TRAMPOLINE \
 136 asm (TRAMPOLINE_TEMPLATE (_dl_runtime_resolve, fixup) \
 137      ".globl _dl_runtime_profile\n" \
 138      ".set _dl_runtime_profile, _dl_runtime_resolve");
 139 #endif
 140 #define ELF_MACHINE_RUNTIME_FIXUP_ARGS long int save_a0, long int save_a1
 141
 142
 143 /* Mask identifying addresses reserved for the user program,
 144    where the dynamic linker should not map anything.  */
 145 #define ELF_MACHINE_USER_ADDRESS_MASK   0x80000000UL
 146
 147 /* Initial entry point code for the dynamic linker.
 148    The C function `_dl_start' is the real entry point;
 149    its return value is the user program's entry point.  */
 150
 151 #define RTLD_START asm ("\
 152         .text
 153         .globl _start
 154         .type _start,@function
 155 _start:
 156         move.l %sp, -(%sp)
 157         jbsr _dl_start
 158         addq.l #4, %sp
 159         /* FALLTHRU */
 160
 161         .globl _dl_start_user
 162         .type _dl_start_user,@function
 163 _dl_start_user:
 164         | Save the user entry point address in %a4.
 165         move.l %d0, %a4
 166         | Point %a5 at the GOT.
 167         lea _GLOBAL_OFFSET_TABLE_@GOTPC(%pc), %a5
 168         | Remember the highest stack address.
 169         move.l %sp, ([__libc_stack_end@GOT.w, %a5])
 170         | See if we were run as a command with the executable file
 171         | name as an extra leading argument.
 172         move.l ([_dl_skip_args@GOT.w, %a5]), %d0
 173         | Pop the original argument count
 174         move.l (%sp)+, %d1
 175         | Subtract _dl_skip_args from it.
 176         sub.l %d0, %d1
 177         | Adjust the stack pointer to skip _dl_skip_args words.
 178         lea (%sp, %d0*4), %sp
 179         | Push back the modified argument count.
 180         move.l %d1, -(%sp)
 181         # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)
 182         pea 8(%sp, %d1*4)
 183         pea 4(%sp)
 184         move.l %d1, -(%sp)
 185         move.l _dl_loaded@GOT.w(%a5), -(%sp)
 186         jbsr _dl_init@PLTPC
 187         addq.l #8, %sp
 188         addq.l #8, %sp
 189         | Pass our finalizer function to the user in %a1.
 190         move.l _dl_fini@GOT.w(%a5), %a1
 191         | Initialize %fp with the stack pointer.
 192         move.l %sp, %fp
 193         | Jump to the user's entry point.
 194         jmp (%a4)
 195         .size _dl_start_user, . - _dl_start_user
 196         .previous");
 197
 198 /* Nonzero iff TYPE describes a relocation that should
 199    skip the executable when looking up the symbol value.  */
 200 #define elf_machine_lookup_noexec_p(type) ((type) == R_68K_COPY)
 201
 202 /* Nonzero iff TYPE describes relocation of a PLT entry, so
 203    PLT entries should not be allowed to define the value.  */
 204 #define elf_machine_lookup_noplt_p(type) ((type) == R_68K_JMP_SLOT)
 205
 206 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 207 #define ELF_MACHINE_JMP_SLOT    R_68K_JMP_SLOT
 208
 209 /* The m68k never uses Elf32_Rel relocations.  */
 210 #define ELF_MACHINE_NO_REL 1
 211
 212 static inline Elf32_Addr
 213 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 214                        const Elf32_Rela *reloc,
 215                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 216 {
 217   return *reloc_addr = value;
 218 }
 219
 220 /* Return the final value of a plt relocation.  On the m68k the JMP_SLOT
 221    relocation ignores the addend.  */
 222 static inline Elf32_Addr
 223 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 224                        Elf32_Addr value)
 225 {
 226   return value;
 227 }
 228
 229 #endif /* !dl_machine_h */
 230
 231 #ifdef RESOLVE
 232
 233 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 234    MAP is the object containing the reloc.  */
 235
 236 static inline void
 237 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 238                   const Elf32_Sym *sym, const struct r_found_version *version,
 239                   Elf32_Addr *const reloc_addr)
 240 {
 241   if (ELF32_R_TYPE (reloc->r_info) == R_68K_RELATIVE)
 242     *reloc_addr = map->l_addr + reloc->r_addend;
 243   else
 244     {
 245       const Elf32_Sym *const refsym = sym;
 246       Elf32_Addr value = RESOLVE (&sym, version, ELF32_R_TYPE (reloc->r_info));
 247       if (sym)
 248         value += sym->st_value;
 249
 250       switch (ELF32_R_TYPE (reloc->r_info))
 251         {
 252         case R_68K_COPY:
 253           if (sym == NULL)
 254             /* This can happen in trace mode if an object could not be
 255                found.  */
 256             break;
 257           if (sym->st_size > refsym->st_size
 258               || (sym->st_size < refsym->st_size && _dl_verbose))
 259             {
 260               extern char **_dl_argv;
 261               const char *strtab;
 262
 263               strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
 264               _dl_sysdep_error (_dl_argv[0] ?: "<program name unknown>",
 265                                 ": Symbol `", strtab + refsym->st_name,
 266                                 "' has different size in shared object, "
 267                                 "consider re-linking\n", NULL);
 268             }
 269           memcpy (reloc_addr, (void *) value, MIN (sym->st_size,
 270                                                    refsym->st_size));
 271           break;
 272         case R_68K_GLOB_DAT:
 273         case R_68K_JMP_SLOT:
 274           *reloc_addr = value;
 275           break;
 276         case R_68K_8:
 277           *(char *) reloc_addr = value + reloc->r_addend;
 278           break;
 279         case R_68K_16:
 280           *(short *) reloc_addr = value + reloc->r_addend;
 281           break;
 282         case R_68K_32:
 283           *reloc_addr = value + reloc->r_addend;
 284           break;
 285         case R_68K_PC8:
 286           *(char *) reloc_addr
 287             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 288           break;
 289         case R_68K_PC16:
 290           *(short *) reloc_addr
 291             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 292           break;
 293         case R_68K_PC32:
 294           *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 295           break;
 296         case R_68K_NONE:                /* Alright, Wilbur.  */
 297           break;
 298         default:
 299           _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 0);
 300           break;
 301         }
 302     }
 303 }
 304
 305 static inline void
 306 elf_machine_lazy_rel (struct link_map *map,
 307                       Elf32_Addr l_addr, const Elf32_Rela *reloc)
 308 {
 309   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 310   if (ELF32_R_TYPE (reloc->r_info) == R_68K_JMP_SLOT)
 311     *reloc_addr += l_addr;
 312   else
 313     _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 1);
 314 }
 315
 316 #endif /* RESOLVE */