sysdeps/cris/dl-machine.h

   1 /* Machine-dependent ELF dynamic relocation inline functions.  CRIS version.
   2    Copyright (C) 1996-2001, 2002, 2003, 2011 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 "CRIS"
  24
  25 #include <sys/param.h>
  26
  27 #ifdef __PIC__
  28 # define CALL_FN(x)                                                           \
  29         "move.d $pc,$r9\n\t"                                                  \
  30         "add.d  " #x " - .,$r9\n\t"                                           \
  31         "jsr    $r9"
  32 #else
  33 # define CALL_FN(x) "jsr " #x
  34 #endif
  35
  36 /* Return nonzero iff ELF header is compatible with the running host.  */
  37
  38 static inline int
  39 elf_machine_matches_host (const Elf32_Ehdr *ehdr)
  40 {
  41   return ehdr->e_machine == EM_CRIS;
  42 }
  43
  44 /* Return the link-time address of _DYNAMIC.  Conveniently, this is the
  45    first element of the GOT.  This must be inlined in a function which
  46    uses global data.  */
  47
  48 static inline Elf32_Addr
  49 elf_machine_dynamic (void)
  50 {
  51   /* Don't just set this to an asm variable "r0" since that's not logical
  52      (like, the variable is uninitialized and the register is fixed) and
  53      may make GCC trip over itself doing register allocation.  Yes, I'm
  54      paranoid.  Why do you ask?  */
  55   Elf32_Addr *got;
  56
  57   __asm__ ("move.d $r0,%0" : "=rm" (got));
  58   return *got;
  59 }
  60
  61 /* Return the run-time load address of the shared object.  We do it like
  62    m68k and i386, by taking an arbitrary local symbol, forcing a GOT entry
  63    for it, and peeking into the GOT table, which is set to the link-time
  64    file-relative symbol value (regardless of whether the target is REL or
  65    RELA).  We subtract this link-time file-relative value from the "local"
  66    value we calculate from GOT position and GOT offset.  FIXME: Perhaps
  67    there's some other symbol we could use, that we don't *have* to force a
  68    GOT entry for.  */
  69
  70 static inline Elf32_Addr
  71 elf_machine_load_address (void)
  72 {
  73   Elf32_Addr gotaddr_diff;
  74   __asm__ ("sub.d [$r0+_dl_start:GOT16],$r0,%0\n\t"
  75            "add.d _dl_start:GOTOFF,%0" : "=r" (gotaddr_diff));
  76   return gotaddr_diff;
  77 }
  78
  79 /* Set up the loaded object described by L so its unrelocated PLT
  80    entries will jump to the on-demand fixup code in dl-runtime.c.  */
  81
  82 static inline int
  83 elf_machine_runtime_setup (struct link_map *l, int lazy, int profile)
  84 {
  85   Elf32_Addr *got;
  86   extern void _dl_runtime_resolve (Elf32_Word);
  87   extern void _dl_runtime_profile (Elf32_Word);
  88
  89   if (l->l_info[DT_JMPREL] && lazy)
  90     {
  91       /* The GOT entries for functions in the PLT have not yet been
  92          filled in.  Their initial contents will arrange when called
  93          to push an offset into the .rela.plt section, push
  94          _GLOBAL_OFFSET_TABLE_[1], and then jump to
  95          _GLOBAL_OFFSET_TABLE_[2].  */
  96       got = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
  97       got[1] = (Elf32_Addr) l;  /* Identify this shared object.  */
  98
  99       /* The got[2] entry contains the address of a function which gets
 100          called to get the address of a so far unresolved function and
 101          jump to it.  The profiling extension of the dynamic linker allows
 102          to intercept the calls to collect information.  In this case we
 103          don't store the address in the GOT so that all future calls also
 104          end in this function.  */
 105       if (__builtin_expect (profile, 0))
 106         {
 107           got[2] = (Elf32_Addr) &_dl_runtime_profile;
 108
 109           if (_dl_name_match_p (GL(dl_profile), l))
 110             {
 111               /* This is the object we are looking for.  Say that we really
 112                  want profiling and the timers are started.  */
 113               GL(dl_profile_map) = l;
 114             }
 115         }
 116       else
 117         /* This function will get called to fix up the GOT entry indicated by
 118            the offset on the stack, and then jump to the resolved address.  */
 119         got[2] = (Elf32_Addr) &_dl_runtime_resolve;
 120     }
 121
 122   return lazy;
 123 }
 124
 125 /* This code is used in dl-runtime.c to call the `fixup' function
 126    and then redirect to the address it returns.
 127
 128    We get here with the offset into the relocation table pushed on stack,
 129    and the link map in MOF.  */
 130
 131 #define TRAMPOLINE_TEMPLATE(tramp_name, fixup_name) \
 132 "; Trampoline for " #fixup_name "\n\
 133         .globl " #tramp_name "\n\
 134         .type " #tramp_name ", @function\n\
 135 " #tramp_name ":\n\
 136         push    $r13\n\
 137         push    $r12\n\
 138         push    $r11\n\
 139         push    $r10\n\
 140         push    $r9\n\
 141         push    $srp\n\
 142         move.d  [$sp+6*4],$r11\n\
 143         move    $mof,$r10\n\
 144         " CALL_FN (fixup_name) "\n\
 145         move.d  $r10,[$sp+6*4]\n\
 146         pop     $srp\n\
 147         pop     $r9\n\
 148         pop     $r10\n\
 149         pop     $r11\n\
 150         pop     $r12\n\
 151         pop     $r13\n\
 152         jump    [$sp+]\n\
 153         .size " #tramp_name ", . - " #tramp_name "\n"
 154 #ifndef PROF
 155 #define ELF_MACHINE_RUNTIME_TRAMPOLINE \
 156 asm (TRAMPOLINE_TEMPLATE (_dl_runtime_resolve, fixup) \
 157      TRAMPOLINE_TEMPLATE (_dl_runtime_profile, profile_fixup));
 158 #else
 159 #define ELF_MACHINE_RUNTIME_TRAMPOLINE \
 160 asm (TRAMPOLINE_TEMPLATE (_dl_runtime_resolve, fixup) \
 161      ".globl _dl_runtime_profile\n" \
 162      ".set _dl_runtime_profile, _dl_runtime_resolve");
 163 #endif
 164
 165
 166 /* Mask identifying addresses reserved for the user program,
 167    where the dynamic linker should not map anything.  */
 168 #define ELF_MACHINE_USER_ADDRESS_MASK   0xf8000000UL
 169
 170 /* Initial entry point code for the dynamic linker.
 171    The C function `_dl_start' is the real entry point;
 172    its return value is the user program's entry point.  */
 173
 174 #define RTLD_START asm ("\
 175         .text\n\
 176         .globl  _start\n\
 177         .type   _start,@function\n\
 178 _start:\n\
 179         move.d  $sp,$r10\n\
 180         " CALL_FN (_dl_start) "\n\
 181         /* FALLTHRU */\n\
 182 \n\
 183         .globl _dl_start_user\n\
 184         .type _dl_start_user,@function\n\
 185 _dl_start_user:\n\
 186         ; Save the user entry point address in R1.\n\
 187         move.d  $r10,$r1\n\
 188         ; Point R0 at the GOT.\n\
 189         move.d  $pc,$r0\n\
 190         sub.d   .:GOTOFF,$r0\n\
 191         ; See if we were run as a command with the executable file\n\
 192         ; name as an extra leading argument.\n\
 193         move.d  [$r0+_dl_skip_args:GOT16],$r13\n\
 194         move.d  [$r13],$r9\n\
 195         ; Get the original argument count\n\
 196         move.d  [$sp],$r11\n\
 197         ; Subtract _dl_skip_args from it.\n\
 198         sub.d   $r9,$r11\n\
 199         ; Adjust the stack pointer to skip _dl_skip_args words.\n\
 200         addi    $r9.d,$sp\n\
 201         ; Put the new argc in place as expected by the user entry.\n\
 202         move.d  $r11,[$sp]\n\
 203         ; Call _dl_init (struct link_map *main_map, int argc, char **argv, char **env)\n\
 204         ;  env: skip scaled argc and skip stored argc and NULL at end of argv[].\n\
 205         move.d  $sp,$r13\n\
 206         addi    $r11.d,$r13\n\
 207         addq    8,$r13\n\
 208         ;  argv: skip stored argc.\n\
 209         move.d  $sp,$r12\n\
 210         addq    4,$r12\n\
 211         ;  main_map: at _dl_loaded.\n\
 212         move.d  [$r0+_rtld_local:GOT16],$r9\n\
 213         move.d  [$r9],$r10\n\
 214         move.d  _dl_init_internal:PLTG,$r9\n\
 215         add.d   $r0,$r9\n\
 216         jsr     $r9\n\
 217         ; Pass our finalizer function to the user in R10.\n\
 218         move.d [$r0+_dl_fini:GOT16],$r10\n\
 219         ; Terminate the frame-pointer.\n\
 220         moveq   0,$r8\n\
 221         ; Cause SEGV if user entry returns.\n\
 222         move    $r8,$srp\n\
 223         ; Jump to the user's entry point.\n\
 224         jump    $r1\n\
 225         .size _dl_start_user, . - _dl_start_user\n\
 226         .previous");
 227
 228 /* The union of reloc-type-classes where the reloc TYPE is a member.
 229
 230    TYPE is in the class ELF_RTYPE_CLASS_PLT if it can describe a
 231    relocation for a PLT entry, that is, for which a PLT entry should not
 232    be allowed to define the value.  The GNU linker for CRIS can merge a
 233    .got.plt entry (R_CRIS_JUMP_SLOT) with a .got entry (R_CRIS_GLOB_DAT),
 234    so we need to match both these reloc types.
 235
 236    TYPE is in the class ELF_RTYPE_CLASS_NOCOPY if it should not be allowed
 237    to resolve to one of the main executable's symbols, as for a COPY
 238    reloc.  */
 239 #define elf_machine_type_class(type)                            \
 240   ((((((type) == R_CRIS_JUMP_SLOT))                             \
 241      || ((type) == R_CRIS_GLOB_DAT)) * ELF_RTYPE_CLASS_PLT)     \
 242    | (((type) == R_CRIS_COPY) * ELF_RTYPE_CLASS_COPY))
 243
 244 /* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
 245 #define ELF_MACHINE_JMP_SLOT    R_CRIS_JUMP_SLOT
 246
 247 /* CRIS never uses Elf32_Rel relocations.  */
 248 #define ELF_MACHINE_NO_REL 1
 249
 250 /* We define an initialization functions.  This is called very early in
 251    _dl_sysdep_start.  */
 252 #define DL_PLATFORM_INIT dl_platform_init ()
 253
 254 static inline void __attribute__ ((unused))
 255 dl_platform_init (void)
 256 {
 257   if (GL(dl_platform) != NULL && *GL(dl_platform) == '\0')
 258     /* Avoid an empty string which would disturb us.  */
 259     GL(dl_platform) = NULL;
 260 }
 261
 262 static inline Elf32_Addr
 263 elf_machine_fixup_plt (struct link_map *map, lookup_t t,
 264                        const Elf32_Rela *reloc,
 265                        Elf32_Addr *reloc_addr, Elf32_Addr value)
 266 {
 267   return *reloc_addr = value;
 268 }
 269
 270 /* Return the final value of a plt relocation.  */
 271 static inline Elf32_Addr
 272 elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
 273                        Elf32_Addr value)
 274 {
 275   return value + reloc->r_addend;
 276 }
 277
 278 #endif /* !dl_machine_h */
 279
 280 #ifdef RESOLVE
 281
 282 /* Perform the relocation specified by RELOC and SYM (which is fully resolved).
 283    MAP is the object containing the reloc.  */
 284
 285 static inline void
 286 elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc,
 287                   const Elf32_Sym *sym, const struct r_found_version *version,
 288                   void *const reloc_addr_arg, int skip_ifunc)
 289 {
 290   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 291   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 292
 293   if (__builtin_expect (r_type == R_CRIS_RELATIVE, 0))
 294     *reloc_addr = map->l_addr + reloc->r_addend;
 295   else
 296     {
 297 #ifndef RTLD_BOOTSTRAP
 298       const Elf32_Sym *const refsym = sym;
 299 #endif
 300       Elf32_Addr value;
 301       if (sym->st_shndx != SHN_UNDEF
 302           && ELF32_ST_BIND (sym->st_info) == STB_LOCAL)
 303         value = map->l_addr;
 304       else
 305         {
 306           value = RESOLVE (&sym, version, r_type);
 307           if (sym)
 308             value += sym->st_value;
 309         }
 310       value += reloc->r_addend; /* Assume copy relocs have zero addend.  */
 311
 312       switch (r_type)
 313         {
 314 #ifndef RTLD_BOOTSTRAP
 315         case R_CRIS_COPY:
 316           if (sym == NULL)
 317             /* This can happen in trace mode if an object could not be
 318                found.  */
 319             break;
 320           if (sym->st_size > refsym->st_size
 321               || (GL(dl_verbose) && sym->st_size < refsym->st_size))
 322             {
 323               const char *strtab;
 324
 325               strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
 326               _dl_error_printf ("\
 327 %s: Symbol `%s' has different size in shared object, consider re-linking\n",
 328                                 rtld_progname ?: "<program name unknown>",
 329                                 strtab + refsym->st_name);
 330             }
 331           memcpy (reloc_addr_arg, (void *) value,
 332                   MIN (sym->st_size, refsym->st_size));
 333           break;
 334
 335         case R_CRIS_32:
 336 #endif
 337         case R_CRIS_GLOB_DAT:
 338         case R_CRIS_JUMP_SLOT:
 339           *reloc_addr = value;
 340           break;
 341 #ifndef RTLD_BOOTSTRAP
 342         case R_CRIS_8:
 343           *(char *) reloc_addr = value;
 344           break;
 345         case R_CRIS_16:
 346           *(short *) reloc_addr = value;
 347           break;
 348         case R_CRIS_8_PCREL:
 349           *(char *) reloc_addr
 350             = value + reloc->r_addend - (Elf32_Addr) reloc_addr - 1;
 351           break;
 352         case R_CRIS_16_PCREL:
 353           *(short *) reloc_addr
 354             = value + reloc->r_addend - (Elf32_Addr) reloc_addr - 2;
 355           break;
 356         case R_CRIS_32_PCREL:
 357           *reloc_addr = value + reloc->r_addend - (Elf32_Addr) reloc_addr - 4;
 358           break;
 359 #endif
 360         case R_CRIS_NONE:
 361           break;
 362 #if !defined RTLD_BOOTSTRAP || defined _NDEBUG
 363         default:
 364           _dl_reloc_bad_type (map, r_type, 0);
 365           break;
 366 #endif
 367         }
 368     }
 369 }
 370
 371 static inline void
 372 elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
 373                            void *const reloc_addr_arg)
 374 {
 375   Elf32_Addr *const reloc_addr = reloc_addr_arg;
 376   *reloc_addr = l_addr + reloc->r_addend;
 377 }
 378
 379 static inline void
 380 elf_machine_lazy_rel (struct link_map *map,
 381                       Elf32_Addr l_addr, const Elf32_Rela *reloc,
 382                       int skip_ifunc)
 383 {
 384   Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
 385   const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
 386   if (__builtin_expect (r_type == R_CRIS_JUMP_SLOT, 1))
 387     *reloc_addr += l_addr;
 388   else
 389     _dl_reloc_bad_type (map, r_type, 1);
 390 }
 391
 392 #endif /* RESOLVE */