sysdeps/m68k/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  m68k version.
   2    Copyright (C) 1996-2017 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, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef dl_machine_h
  20 #define dl_machine_h
  21
  22 #define ELF_MACHINE_NAME "m68k"
  23
  24 #include <sys/param.h>
  25 #include <sysdep.h>
  26 #include <dl-tls.h>
  27
  28 /* Return nonzero iff ELF header is compatible with the running host.  */
  29 static inline int
  30 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
  31 {
  32   return ehdr->e_machine == EM_68K;
  33 }
  34
  35
  36 /* Return the link-time address of _DYNAMIC.
  37    This must be inlined in a function which uses global data.  */
  38 static inline Elf32_Addr
  39 elf_machine_dynamic (void)
  40 {
  41   Elf32_Addr addr;
  42
  43   asm ("move.l _DYNAMIC@GOT.w(%%a5), %0"
  44        : "=a" (addr));
  45   return addr;
  46 }
  47
  48
  49 /* Return the run-time load address of the shared object.  */
  50 static inline Elf32_Addr
  51 elf_machine_load_address (void)
  52 {
  53   Elf32_Addr addr;
  54   asm (PCREL_OP ("lea", "_dl_start", "%0", "%0", "%%pc") "\n\t"
  55        "sub.l _dl_start@GOT.w(%%a5), %0"
  56        : "=a" (addr));
  57   return addr;
  58 }
  59
  60
  61 /* Set up the loaded object described by L so its unrelocated PLT
  62    entries will jump to the on-demand fixup code in dl-runtime.c.  */
  63
  64 static inline int __attribute__ ((always_inline))
  65 elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
  66 {
  67   Elf32_Addr *got;
  68   extern void _dl_runtime_resolve (Elf32_Word);
  69   extern void _dl_runtime_profile (Elf32_Word);
  70
  71   if (l->l_info[DT_JMPREL] && lazy)
  72     {
  73       /* The GOT entries for functions in the PLT have not yet been
  74          filled in.  Their initial contents will arrange when called
  75          to push an offset into the .rela.plt section, push
  76          _GLOBAL_OFFSET_TABLE_[1], and then jump to
  77          _GLOBAL_OFFSET_TABLE_[2].  */
  78       got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
  79       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
  80
  81       /* The got[2] entry contains the address of a function which gets
  82          called to get the address of a so far unresolved function and
  83          jump to it.  The profiling extension of the dynamic linker allows
  84          to intercept the calls to collect information.  In this case we
  85          don't store the address in the GOT so that all future calls also
  86          end in this function.  */
  87       if (profile)
  88         {
  89           got[2] = (Elf32_Addr) &_dl_runtime_profile;
  90
  91           if (GLRO(dl_profile) != NULL
  92               && _dl_name_match_p (GLRO(dl_profile), l))
  93             {
  94               /* This is the object we are looking for.  Say that we really
  95                  want profiling and the timers are started.  */
  96               GL(dl_profile_map) = l;
  97             }
  98         }
  99       else
 100         /* This function will get called to fix up the GOT entry indicated by
 101            the offset on the stack, and then jump to the resolved address.  */
 102         got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 103     }
 104
 105   return lazy;
 106 }
 107
 108 #define ELF_MACHINE_RUNTIME_FIXUP_ARGS long int save_a0, long int save_a1
 109 #define ELF_MACHINE_RUNTIME_FIXUP_PARAMS save_a0, save_a1
 110
 111
 112 /* Mask identifying addresses reserved for the user program,
 113    where the dynamic linker should not map anything.  */
 114 #define ELF_MACHINE_USER_ADDRESS_MASK   0x80000000UL
 115
 116 /* Initial entry point code for the dynamic linker.
 117    The C function `_dl_start' is the real entry point;
 118    its return value is the user program's entry point.  */
 119
 120 #define RTLD_START asm ("\
 121         .text\n\
 122         .globl _start\n\
 123         .type _start,@function\n\
 124 _start:\n\
 125         sub.l %fp, %fp\n\
 126         move.l %sp, -(%sp)\n\
 127         jbsr _dl_start\n\
 128         addq.l #4, %sp\n\
 129         /* FALLTHRU */\n\
 130 \n\
 131         .globl _dl_start_user\n\
 132         .type _dl_start_user,@function\n\
 133 _dl_start_user:\n\
 134         | Save the user entry point address in %a4.\n\
 135         move.l %d0, %a4\n\
 136         | See if we were run as a command with the executable file\n\
 137         | name as an extra leading argument.\n\
 138         " PCREL_OP ("move.l", "_dl_skip_args", "%d0", "%d0", "%pc") "\n\
 139         | Pop the original argument count\n\
 140         move.l (%sp)+, %d1\n\
 141         | Subtract _dl_skip_args from it.\n\
 142         sub.l %d0, %d1\n\
 143         | Adjust the stack pointer to skip _dl_skip_args words.\n\
 144         lea (%sp, %d0*4), %sp\n\
 145         | Push back the modified argument count.\n\
 146         move.l %d1, -(%sp)\n\
 147         # Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
 148         pea 8(%sp, %d1*4)\n\
 149         pea 8(%sp)\n\
 150         move.l %d1, -(%sp)\n\
 151         " PCREL_OP ("move.l", "_rtld_local", "-(%sp)", "%d0", "%pc") "\n\
 152         jbsr _dl_init\n\
 153         addq.l #8, %sp\n\
 154         addq.l #8, %sp\n\
 155         | Pass our finalizer function to the user in %a1.\n\
 156         " PCREL_OP ("lea", "_dl_fini", "%a1", "%a1", "%pc") "\n\
 157         | Initialize %fp with the stack pointer.\n\
 158         move.l %sp, %fp\n\
 159         | Jump to the user's entry point.\n\
 160         jmp (%a4)\n\
 161         .size _dl_start_user, . - _dl_start_user\n\
 162         .previous");
 163
 164 /* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry or
 165    TLS variable, so undefined references should not be allowed to
 166    define the value.
 167    ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
 168    of the main executable's symbols, as for a COPY reloc.  */
 169 #define elf_machine_type_class(type) \
 170   ((((type) == R_68K_JMP_SLOT        \
 171      || (type) == R_68K_TLS_DTPMOD32 \
 172      || (type) == R_68K_TLS_DTPREL32 \
 173      || (type) == R_68K_TLS_TPREL32) * ELF_RTYPE_CLASS_PLT)     \
 174    | (((type) == R_68K_COPY) * ELF_RTYPE_CLASS_COPY))
 175
 176 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 177 #define ELF_MACHINE_JMP_SLOT    R_68K_JMP_SLOT
 178
 179 /* The m68k never uses Elf32_Rel relocations.  */
 180 #define ELF_MACHINE_NO_REL 1
 181 #define ELF_MACHINE_NO_RELA 0
 182
 183 static inline Elf32_Addr
 184 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 185                        const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
 186                        const Elf32_Rela *reloc,
 187                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 188 {
 189   return *reloc_addr = value;
 190 }
 191
 192 /* Return the final value of a plt relocation.  On the m68k the JMP_SLOT
 193    relocation ignores the addend.  */
 194 static inline Elf32_Addr
 195 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 196                        Elf32_Addr value)
 197 {
 198   return value;
 199 }
 200
 201 /* Names of the architecture-specific auditing callback functions.  */
 202 #define ARCH_LA_PLTENTER m68k_gnu_pltenter
 203 #define ARCH_LA_PLTEXIT m68k_gnu_pltexit
 204
 205 #endif /* !dl_machine_h */
 206
 207 #ifdef RESOLVE_MAP
 208
 209 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 210    MAP is the object containing the reloc.  */
 211
 212 auto inline void __attribute__ ((unused, always_inline))
 213 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 214                   const Elf32_Sym *sym, const struct r_found_version *version,
 215                   void *const reloc_addr_arg, int skip_ifunc)
 216 {
 217   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 218   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 219
 220   if (__builtin_expect (r_type == R_68K_RELATIVE, 0))
 221     *reloc_addr = map->l_addr + reloc->r_addend;
 222   else
 223     {
 224       const Elf32_Sym *const refsym = sym;
 225       struct link_map *sym_map = RESOLVE_MAP (&sym, version, r_type);
 226       Elf32_Addr value = sym == NULL ? 0 : sym_map->l_addr + sym->st_value;
 227
 228       switch (r_type)
 229         {
 230         case R_68K_COPY:
 231           if (sym == NULL)
 232             /* This can happen in trace mode if an object could not be
 233                found.  */
 234             break;
 235           if (sym->st_size > refsym->st_size
 236               || (sym->st_size < refsym->st_size && GLRO(dl_verbose)))
 237             {
 238               const char *strtab;
 239
 240               strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
 241               _dl_error_printf ("\
 242 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 243                                 RTLD_PROGNAME, 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 #ifndef 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 /* !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                       int skip_ifunc)
 312 {
 313   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 314   if (ELF32_R_TYPE (reloc->r_info) == R_68K_JMP_SLOT)
 315     *reloc_addr += l_addr;
 316   else
 317     _dl_reloc_bad_type (map, ELF32_R_TYPE (reloc->r_info), 1);
 318 }
 319
 320 #endif /* RESOLVE_MAP */