sysdeps/m68k/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  m68k version.
   2    Copyright (C) 1996, 1997 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 #include <assert.h>
  28
  29 /* Return nonzero iff E_MACHINE is compatible with the running host.  */
  30 static inline int
  31 elf_machine_matches_host (Elf32_Half e_machine)
  32 {
  33   switch (e_machine)
  34     {
  35     case EM_68K:
  36       return 1;
  37     default:
  38       return 0;
  39     }
  40 }
  41
  42
  43 /* Return the link-time address of _DYNAMIC.  Conveniently, this is the
  44    first element of the GOT.  This must be inlined in a function which
  45    uses global data.  */
  46 static inline Elf32_Addr
  47 elf_machine_dynamic (void)
  48 {
  49   register Elf32_Addr *got asm ("%a5");
  50   return *got;
  51 }
  52
  53
  54 /* Return the run-time load address of the shared object.  */
  55 static inline Elf32_Addr
  56 elf_machine_load_address (void)
  57 {
  58   Elf32_Addr addr;
  59   asm ("1: lea 1b(%%pc), %0\n"
  60        "   sub.l 1b@GOTPC(%%pc), %0"
  61        : "=a" (addr));
  62   return addr;
  63 }
  64
  65
  66 /* Set up the loaded object described by L so its unrelocated PLT
  67    entries will jump to the on-demand fixup code in dl-runtime.c.  */
  68
  69 static inline int
  70 elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
  71 {
  72   Elf32_Addr *got;
  73   extern void _dl_runtime_resolve (Elf32_Word);
  74   extern void _dl_runtime_profile (Elf32_Word);
  75
  76   if (l->l_info[DT_JMPREL] && lazy)
  77     {
  78       /* The GOT entries for functions in the PLT have not yet been
  79          filled in.  Their initial contents will arrange when called
  80          to push an offset into the .rela.plt section, push
  81          _GLOBAL_OFFSET_TABLE_[1], and then jump to
  82          _GLOBAL_OFFSET_TABLE_[2].  */
  83       got = (Elf32_Addr *) (l->l_addr + l->l_info[DT_PLTGOT]->d_un.d_ptr);
  84       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
  85
  86       /* The got[2] entry contains the address of a function which gets
  87          called to get the address of a so far unresolved function and
  88          jump to it.  The profiling extension of the dynamic linker allows
  89          to intercept the calls to collect information.  In this case we
  90          don't store the address in the GOT so that all future calls also
  91          end in this function.  */
  92       if (profile)
  93         {
  94           got[2] = (Elf32_Addr) &_dl_runtime_profile;
  95           /* Say that we really want profiling and the timers are started.  */
  96           _dl_profile_map = l;
  97         }
  98       else
  99         /* This function will get called to fix up the GOT entry indicated by
 100            the offset on the stack, and then jump to the resolved address.  */
 101         got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 102     }
 103
 104   return lazy;
 105 }
 106
 107 /* This code is used in dl-runtime.c to call the `fixup' function
 108    and then redirect to the address it returns.  */
 109 #define TRAMPOLINE_TEMPLATE(tramp_name, fixup_name) \
 110 "| Trampoline for " #fixup_name "
 111         .globl " #tramp_name "
 112         .type " #tramp_name ", @function
 113 " #tramp_name ":
 114         | Save %a0 (struct return address) and %a1.
 115         move.l %a0, -(%sp)
 116         move.l %a1, -(%sp)
 117         | Call the real address resolver.
 118         jbsr " #fixup_name "
 119         | Restore register %a0 and %a1.
 120         move.l (%sp)+, %a1
 121         move.l (%sp)+, %a0
 122         | Pop parameters
 123         addq.l #8, %sp
 124         | Call real function.
 125         jmp (%d0)
 126         .size " #tramp_name ", . - " #tramp_name "\n"
 127 #ifndef PROF
 128 #define ELF_MACHINE_RUNTIME_TRAMPOLINE \
 129 asm (TRAMPOLINE_TEMPLATE (_dl_runtime_resolve, fixup) \
 130      TRAMPOLINE_TEMPLATE (_dl_runtime_profile, profile_fixup));
 131 #else
 132 #define ELF_MACHINE_RUNTIME_TRAMPOLINE \
 133 asm (TRAMPOLINE_TEMPLATE (_dl_runtime_resolve, fixup) \
 134      ".globl _dl_runtime_profile\n" \
 135      ".set _dl_runtime_profile, _dl_runtime_resolve");
 136 #endif
 137 #define ELF_MACHINE_RUNTIME_FIXUP_ARGS long int save_a0, long int save_a1
 138 /* The PLT uses Elf32_Rela relocs.  */
 139 #define elf_machine_relplt elf_machine_rela
 140
 141
 142 /* Mask identifying addresses reserved for the user program,
 143    where the dynamic linker should not map anything.  */
 144 #define ELF_MACHINE_USER_ADDRESS_MASK   0x80000000UL
 145
 146 /* Initial entry point code for the dynamic linker.
 147    The C function `_dl_start' is the real entry point;
 148    its return value is the user program's entry point.  */
 149
 150 #define RTLD_START asm ("\
 151         .text
 152         .globl _start
 153         .type _start,@function
 154 _start:
 155         move.l %sp, -(%sp)
 156         jbsr _dl_start
 157         addq.l #4, %sp
 158
 159         .globl _dl_start_user
 160         .type _dl_start_user,@function
 161 _dl_start_user:
 162         | Save the user entry point address in %a4.
 163         move.l %d0, %a4
 164         | Point %a5 at the GOT.
 165         lea _GLOBAL_OFFSET_TABLE_@GOTPC(%pc), %a5
 166         | See if we were run as a command with the executable file
 167         | name as an extra leading argument.
 168         move.l ([_dl_skip_args@GOT, %a5]), %d0
 169         jeq 0f
 170         | Pop the original argument count
 171         move.l (%sp)+, %d1
 172         | Subtract _dl_skip_args from it.
 173         sub.l %d0, %d1
 174         | Adjust the stack pointer to skip _dl_skip_args words.
 175         lea (%sp, %d0*4), %sp
 176         | Push back the modified argument count.
 177         move.l %d1, -(%sp)
 178 0:      | Push _dl_default_scope[2] as argument in _dl_init_next call below.
 179         move.l ([_dl_default_scope@GOT, %a5], 8), %d2
 180 0:      move.l %d2, -(%sp)
 181         | Call _dl_init_next to return the address of an initializer
 182         | function to run.
 183         bsr.l _dl_init_next@PLTPC
 184         add.l #4, %sp | Pop argument.
 185         | Check for zero return, when out of initializers.
 186         tst.l %d0
 187         jeq 1f
 188         | Call the shared object initializer function.
 189         | NOTE: We depend only on the registers (%d2, %a4 and %a5)
 190         | and the return address pushed by this call;
 191         | the initializer is called with the stack just
 192         | as it appears on entry, and it is free to move
 193         | the stack around, as long as it winds up jumping to
 194         | the return address on the top of the stack.
 195         move.l %d0, %a0
 196         jsr (%a0)
 197         | Loop to call _dl_init_next for the next initializer.
 198         jra 0b
 199 1:      | Clear the startup flag.
 200         clr.l _dl_starting_up@GOT(%a5)
 201         | Pass our finalizer function to the user in %a1.
 202         move.l _dl_fini@GOT(%a5), %a1
 203         | Initialize %fp with the stack pointer.
 204         move.l %sp, %fp
 205         | Jump to the user's entry point.
 206         jmp (%a4)
 207         .size _dl_start_user, . - _dl_start_user
 208         .previous");
 209
 210 /* Nonzero iff TYPE describes a relocation that should
 211    skip the executable when looking up the symbol value.  */
 212 #define elf_machine_lookup_noexec_p(type) ((type) == R_68K_COPY)
 213
 214 /* Nonzero iff TYPE describes relocation of a PLT entry, so
 215    PLT entries should not be allowed to define the value.  */
 216 #define elf_machine_lookup_noplt_p(type) ((type) == R_68K_JMP_SLOT)
 217
 218 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 219 #define ELF_MACHINE_RELOC_NOPLT R_68K_JMP_SLOT
 220
 221 /* The m68k never uses Elf32_Rel relocations.  */
 222 #define ELF_MACHINE_NO_REL 1
 223
 224 #endif /* !dl_machine_h */
 225
 226 #ifdef RESOLVE
 227
 228 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 229    MAP is the object containing the reloc.  */
 230
 231 static inline void
 232 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 233                   const Elf32_Sym *sym, const struct r_found_version *version,
 234                   Elf32_Addr *const reloc_addr)
 235 {
 236   if (ELF32_R_TYPE (reloc->r_info) == R_68K_RELATIVE)
 237     *reloc_addr = map->l_addr + reloc->r_addend;
 238   else
 239     {
 240       const Elf32_Sym *const refsym = sym;
 241       Elf32_Addr value = RESOLVE (&sym, version, ELF32_R_TYPE (reloc->r_info));
 242       if (sym)
 243         value += sym->st_value;
 244
 245       switch (ELF32_R_TYPE (reloc->r_info))
 246         {
 247         case R_68K_COPY:
 248           if (sym == NULL)
 249             /* This can happen in trace mode if an object could not be
 250                found.  */
 251             break;
 252           if (sym->st_size > refsym->st_size
 253               || (_dl_verbose && sym->st_size < refsym->st_size))
 254             {
 255               extern char **_dl_argv;
 256               const char *strtab;
 257
 258               strtab = ((void *) map->l_addr
 259                         + map->l_info[DT_STRTAB]->d_un.d_ptr);
 260               _dl_sysdep_error (_dl_argv[0] ?: "<program name unknown>",
 261                                 ": Symbol `", strtab + refsym->st_name,
 262                                 "' has different size in shared object, "
 263                                 "consider re-linking\n", NULL);
 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           assert (! "unexpected dynamic reloc type");
 296           break;
 297         }
 298     }
 299 }
 300
 301 static inline void
 302 elf_machine_lazy_rel (struct link_map *map, const Elf32_Rela *reloc)
 303 {
 304   Elf32_Addr *const reloc_addr = (void *) (map->l_addr + reloc->r_offset);
 305   switch (ELF32_R_TYPE (reloc->r_info))
 306     {
 307     case R_68K_JMP_SLOT:
 308       *reloc_addr += map->l_addr;
 309       break;
 310     default:
 311       assert (! "unexpected PLT reloc type");
 312       break;
 313     }
 314 }
 315
 316 #endif /* RESOLVE */