sysdeps/m68k/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  m68k version.
   2    Copyright (C) 1996-2001, 2002, 2003, 2004, 2005, 2010
   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 #ifndef dl_machine_h
  22 #define dl_machine_h
  23
  24 #define ELF_MACHINE_NAME "m68k"
  25
  26 #include <sys/param.h>
  27 #include <sysdep.h>
  28 #include <dl-tls.h>
  29
  30 /* Return nonzero iff ELF header is compatible with the running host.  */
  31 static inline int
  32 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
  33 {
  34   return ehdr->e_machine == EM_68K;
  35 }
  36
  37
  38 /* Return the link-time address of _DYNAMIC.
  39    This must be inlined in a function which uses global data.  */
  40 static inline Elf32_Addr
  41 elf_machine_dynamic (void)
  42 {
  43   Elf32_Addr addr;
  44
  45   asm ("move.l _DYNAMIC@GOT.w(%%a5), %0"
  46        : "=a" (addr));
  47   return addr;
  48 }
  49
  50
  51 /* Return the run-time load address of the shared object.  */
  52 static inline Elf32_Addr
  53 elf_machine_load_address (void)
  54 {
  55   Elf32_Addr addr;
  56   asm (PCREL_OP ("lea", "_dl_start", "%0", "%0", "%%pc") "\n\t"
  57        "sub.l _dl_start@GOT.w(%%a5), %0"
  58        : "=a" (addr));
  59   return addr;
  60 }
  61
  62
  63 /* Set up the loaded object described by L so its unrelocated PLT
  64    entries will jump to the on-demand fixup code in dl-runtime.c.  */
  65
  66 static inline int __attribute__ ((always_inline))
  67 elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
  68 {
  69   Elf32_Addr *got;
  70   extern void _dl_runtime_resolve (Elf32_Word);
  71   extern void _dl_runtime_profile (Elf32_Word);
  72
  73   if (l->l_info[DT_JMPREL] && lazy)
  74     {
  75       /* The GOT entries for functions in the PLT have not yet been
  76          filled in.  Their initial contents will arrange when called
  77          to push an offset into the .rela.plt section, push
  78          _GLOBAL_OFFSET_TABLE_[1], and then jump to
  79          _GLOBAL_OFFSET_TABLE_[2].  */
  80       got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
  81       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
  82
  83       /* The got[2] entry contains the address of a function which gets
  84          called to get the address of a so far unresolved function and
  85          jump to it.  The profiling extension of the dynamic linker allows
  86          to intercept the calls to collect information.  In this case we
  87          don't store the address in the GOT so that all future calls also
  88          end in this function.  */
  89       if (profile)
  90         {
  91           got[2] = (Elf32_Addr) &_dl_runtime_profile;
  92
  93           if (GLRO(dl_profile) != NULL
  94               && _dl_name_match_p (GLRO(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               GL(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 #define ELF_MACHINE_RUNTIME_FIXUP_ARGS long int save_a0, long int save_a1
 111
 112
 113 /* Mask identifying addresses reserved for the user program,
 114    where the dynamic linker should not map anything.  */
 115 #define ELF_MACHINE_USER_ADDRESS_MASK   0x80000000UL
 116
 117 /* Initial entry point code for the dynamic linker.
 118    The C function `_dl_start' is the real entry point;
 119    its return value is the user program's entry point.  */
 120
 121 #define RTLD_START asm ("\
 122         .text\n\
 123         .globl _start\n\
 124         .type _start,@function\n\
 125 _start:\n\
 126         sub.l %fp, %fp\n\
 127         move.l %sp, -(%sp)\n\
 128         jbsr _dl_start\n\
 129         addq.l #4, %sp\n\
 130         /* FALLTHRU */\n\
 131 \n\
 132         .globl _dl_start_user\n\
 133         .type _dl_start_user,@function\n\
 134 _dl_start_user:\n\
 135         | Save the user entry point address in %a4.\n\
 136         move.l %d0, %a4\n\
 137         | See if we were run as a command with the executable file\n\
 138         | name as an extra leading argument.\n\
 139         " PCREL_OP ("move.l", "_dl_skip_args", "%d0", "%d0", "%pc") "\n\
 140         | Pop the original argument count\n\
 141         move.l (%sp)+, %d1\n\
 142         | Subtract _dl_skip_args from it.\n\
 143         sub.l %d0, %d1\n\
 144         | Adjust the stack pointer to skip _dl_skip_args words.\n\
 145         lea (%sp, %d0*4), %sp\n\
 146         | Push back the modified argument count.\n\
 147         move.l %d1, -(%sp)\n\
 148         # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
 149         pea 8(%sp, %d1*4)\n\
 150         pea 8(%sp)\n\
 151         move.l %d1, -(%sp)\n\
 152         " PCREL_OP ("move.l", "_rtld_local", "-(%sp)", "%d0", "%pc") "\n\
 153         jbsr _dl_init_internal@PLTPC\n\
 154         addq.l #8, %sp\n\
 155         addq.l #8, %sp\n\
 156         | Pass our finalizer function to the user in %a1.\n\
 157         " PCREL_OP ("lea", "_dl_fini", "%a1", "%a1", "%pc") "\n\
 158         | Initialize %fp with the stack pointer.\n\
 159         move.l %sp, %fp\n\
 160         | Jump to the user's entry point.\n\
 161         jmp (%a4)\n\
 162         .size _dl_start_user, . - _dl_start_user\n\
 163         .previous");
 164
 165 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
 166    TLS variable, so undefined references should not be allowed to
 167    define the value.
 168    ELF_RTYPE_CLASS_NOCOPY iff TYPE should not be allowed to resolve to one
 169    of the main executable's symbols, as for a COPY reloc.  */
 170 #define elf_machine_type_class(type) \
 171   ((((type) == R_68K_JMP_SLOT        \
 172      || (type) == R_68K_TLS_DTPMOD32 \
 173      || (type) == R_68K_TLS_DTPREL32 \
 174      || (type) == R_68K_TLS_TPREL32) * ELF_RTYPE_CLASS_PLT)     \
 175    | (((type) == R_68K_COPY) * ELF_RTYPE_CLASS_COPY))
 176
 177 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 178 #define ELF_MACHINE_JMP_SLOT    R_68K_JMP_SLOT
 179
 180 /* The m68k never uses Elf32_Rel relocations.  */
 181 #define ELF_MACHINE_NO_REL 1
 182
 183 static inline Elf32_Addr
 184 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 185                        const Elf32_Rela *reloc,
 186                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 187 {
 188   return *reloc_addr = value;
 189 }
 190
 191 /* Return the final value of a plt relocation.  On the m68k the JMP_SLOT
 192    relocation ignores the addend.  */
 193 static inline Elf32_Addr
 194 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 195                        Elf32_Addr value)
 196 {
 197   return value;
 198 }
 199
 200 /* Names of the architecture-specific auditing callback functions.  */
 201 #define ARCH_LA_PLTENTER m68k_gnu_pltenter
 202 #define ARCH_LA_PLTEXIT m68k_gnu_pltexit
 203
 204 #endif /* !dl_machine_h */
 205
 206 #ifdef RESOLVE_MAP
 207
 208 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 209    MAP is the object containing the reloc.  */
 210
 211 auto inline void __attribute__ ((unused, always_inline))
 212 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 213                   const Elf32_Sym *sym, const struct r_found_version *version,
 214                   void *const reloc_addr_arg)
 215 {
 216   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 217   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 218
 219   if (__builtin_expect (r_type == R_68K_RELATIVE, 0))
 220     *reloc_addr = map->l_addr + reloc->r_addend;
 221   else
 222     {
 223       const Elf32_Sym *const refsym = sym;
 224       struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
 225       Elf32_Addr value = sym == NULL ? 0 : sym_map->l_addr + sym->st_value;
 226
 227       switch (r_type)
 228         {
 229         case R_68K_COPY:
 230           if (sym == NULL)
 231             /* This can happen in trace mode if an object could not be
 232                found.  */
 233             break;
 234           if (sym->st_size > refsym->st_size
 235               || (sym->st_size < refsym->st_size && GLRO(dl_verbose)))
 236             {
 237               const char *strtab;
 238
 239               strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
 240               _dl_error_printf ("\
 241 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 242                                 rtld_progname ?: "<program name unknown>",
 243                                 strtab + refsym->st_name);
 244             }
 245           memcpy (reloc_addr_arg, (void *) value,
 246                   MIN (sym->st_size, refsym->st_size));
 247           break;
 248         case R_68K_GLOB_DAT:
 249         case R_68K_JMP_SLOT:
 250           *reloc_addr = value;
 251           break;
 252         case R_68K_8:
 253           *(char *) reloc_addr = value + reloc->r_addend;
 254           break;
 255         case R_68K_16:
 256           *(short *) reloc_addr = value + reloc->r_addend;
 257           break;
 258         case R_68K_32:
 259           *reloc_addr = value + reloc->r_addend;
 260           break;
 261         case R_68K_PC8:
 262           *(char *) reloc_addr
 263             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 264           break;
 265         case R_68K_PC16:
 266           *(short *) reloc_addr
 267             = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 268           break;
 269         case R_68K_PC32:
 270           *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr;
 271           break;
 272 #if defined USE_TLS && !defined RTLD_BOOTSTRAP
 273         case R_68K_TLS_DTPMOD32:
 274           /* Get the information from the link map returned by the
 275              resolv function.  */
 276           if (sym_map != NULL)
 277             *reloc_addr = sym_map->l_tls_modid;
 278           break;
 279         case R_68K_TLS_DTPREL32:
 280           if (sym != NULL)
 281             *reloc_addr = TLS_DTPREL_VALUE (sym, reloc);
 282           break;
 283         case R_68K_TLS_TPREL32:
 284           if (sym != NULL)
 285             {
 286               CHECK_STATIC_TLS (map, sym_map);
 287               *reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
 288             }
 289           break;
 290 #endif /* defined USE_TLS && !defined RTLD_BOOTSTRAP */
 291         case R_68K_NONE:                /* Alright, Wilbur.  */
 292           break;
 293         default:
 294           _dl_reloc_bad_type (map, r_type, 0);
 295           break;
 296         }
 297     }
 298 }
 299
 300 auto inline void __attribute__ ((unused, always_inline))
 301 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
 302                            void *const reloc_addr_arg)
 303 {
 304   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 305   *reloc_addr = l_addr + reloc->r_addend;
 306 }
 307
 308 auto inline void __attribute__ ((unused, always_inline))
 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_MAP */