libexec/ld.elf_so/arch/mips/mips_reloc.c

   1 /*      $NetBSD: mips_reloc.c,v 1.63 2014/08/25 20:40:52 joerg Exp $    */
   2
   3 /*
   4  * Copyright 1997 Michael L. Hitch <mhitch@montana.edu>
   5  * Portions copyright 2002 Charles M. Hannum <root@ihack.net>
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. The name of the author may not be used to endorse or promote products
  17  *    derived from this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  */
  30
  31 #include <sys/cdefs.h>
  32 #ifndef lint
  33 __RCSID("$NetBSD: mips_reloc.c,v 1.63 2014/08/25 20:40:52 joerg Exp $");
  34 #endif /* not lint */
  35
  36 #include <sys/types.h>
  37 #include <sys/endian.h>
  38 #include <sys/tls.h>
  39
  40 #include <stdlib.h>
  41 #include <string.h>
  42
  43 #include "debug.h"
  44 #include "rtld.h"
  45
  46 #ifdef __mips_o32
  47 #define SUPPORT_OLD_BROKEN_LD
  48 #endif
  49
  50 void _rtld_bind_start(void);
  51 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
  52 caddr_t _rtld_bind(Elf_Word, Elf_Addr, Elf_Addr, Elf_Addr);
  53
  54 /*
  55  * It is possible for the compiler to emit relocations for unaligned data.
  56  * We handle this situation with these inlines.
  57  */
  58
  59 #if ELFSIZE == 64
  60 /*
  61  * ELF64 MIPS encodes the relocs uniquely.  The first 32-bits of info contain
  62  * the symbol index.  The top 32-bits contain three relocation types encoded
  63  * in big-endian integer with first relocation in LSB.  This means for little
  64  * endian we have to byte swap that interger (r_type).
  65  */
  66 #define Elf_Sxword                      Elf64_Sxword
  67 #define ELF_R_NXTTYPE_64_P(r_type)      ((((r_type) >> 8) & 0xff) == R_TYPE(64))
  68 #if BYTE_ORDER == LITTLE_ENDIAN
  69 #undef ELF_R_SYM
  70 #undef ELF_R_TYPE
  71 #define ELF_R_SYM(r_info)               ((r_info) & 0xffffffff)
  72 #define ELF_R_TYPE(r_info)              bswap32((r_info) >> 32)
  73 #endif
  74 #else
  75 #define ELF_R_NXTTYPE_64_P(r_type)      (0)
  76 #define Elf_Sxword                      Elf32_Sword
  77 #endif
  78 #define GOT1_MASK                       (~(Elf_Addr)0 >> 1)
  79
  80 static inline Elf_Sxword
  81 load_ptr(void *where, size_t len)
  82 {
  83         Elf_Sxword val;
  84
  85         if (__predict_true(((uintptr_t)where & (len - 1)) == 0)) {
  86 #if ELFSIZE == 64
  87                 if (len == sizeof(Elf_Sxword))
  88                         return *(Elf_Sxword *)where;
  89 #endif
  90                 return *(Elf_Sword *)where;
  91         }
  92
  93         val = 0;
  94 #if BYTE_ORDER == LITTLE_ENDIAN
  95         (void)memcpy(&val, where, len);
  96 #endif
  97 #if BYTE_ORDER == BIG_ENDIAN
  98         (void)memcpy((uint8_t *)((&val)+1) - len, where, len);
  99 #endif
 100         return (len == sizeof(Elf_Sxword)) ? val : (Elf_Sword)val;
 101 }
 102
 103 static inline void
 104 store_ptr(void *where, Elf_Sxword val, size_t len)
 105 {
 106         if (__predict_true(((uintptr_t)where & (len - 1)) == 0)) {
 107 #if ELFSIZE == 64
 108                 if (len == sizeof(Elf_Sxword)) {
 109                         *(Elf_Sxword *)where = val;
 110                         return;
 111                 }
 112 #endif
 113                 *(Elf_Sword *)where = val;
 114                 return;
 115         }
 116 #if BYTE_ORDER == LITTLE_ENDIAN
 117         (void)memcpy(where, &val, len);
 118 #endif
 119 #if BYTE_ORDER == BIG_ENDIAN
 120         (void)memcpy(where, (const uint8_t *)((&val)+1) - len, len);
 121 #endif
 122 }
 123
 124
 125 void
 126 _rtld_setup_pltgot(const Obj_Entry *obj)
 127 {
 128         obj->pltgot[0] = (Elf_Addr) &_rtld_bind_start;
 129         /* XXX only if obj->pltgot[1] & 0x80000000 ?? */
 130         obj->pltgot[1] |= (Elf_Addr) obj;
 131 }
 132
 133 void
 134 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
 135 {
 136         const Elf_Rel *rel = 0, *rellim;
 137         Elf_Addr relsz = 0;
 138         void *where;
 139         const Elf_Sym *symtab = NULL, *sym;
 140         Elf_Addr *got = NULL;
 141         Elf_Word local_gotno = 0, symtabno = 0, gotsym = 0;
 142         size_t i;
 143
 144         for (; dynp->d_tag != DT_NULL; dynp++) {
 145                 switch (dynp->d_tag) {
 146                 case DT_REL:
 147                         rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr);
 148                         break;
 149                 case DT_RELSZ:
 150                         relsz = dynp->d_un.d_val;
 151                         break;
 152                 case DT_SYMTAB:
 153                         symtab = (const Elf_Sym *)(relocbase + dynp->d_un.d_ptr);
 154                         break;
 155                 case DT_PLTGOT:
 156                         got = (Elf_Addr *)(relocbase + dynp->d_un.d_ptr);
 157                         break;
 158                 case DT_MIPS_LOCAL_GOTNO:
 159                         local_gotno = dynp->d_un.d_val;
 160                         break;
 161                 case DT_MIPS_SYMTABNO:
 162                         symtabno = dynp->d_un.d_val;
 163                         break;
 164                 case DT_MIPS_GOTSYM:
 165                         gotsym = dynp->d_un.d_val;
 166                         break;
 167                 }
 168         }
 169
 170         i = (got[1] & 0x80000000) ? 2 : 1;
 171         /* Relocate the local GOT entries */
 172         got += i;
 173         for (; i < local_gotno; i++)
 174                 *got++ += relocbase;
 175         sym = symtab + gotsym;
 176         /* Now do the global GOT entries */
 177         for (i = gotsym; i < symtabno; i++) {
 178                 *got = sym->st_value + relocbase;
 179                 ++sym;
 180                 ++got;
 181         }
 182
 183         rellim = (const Elf_Rel *)((uintptr_t)rel + relsz);
 184         for (; rel < rellim; rel++) {
 185                 Elf_Word r_symndx, r_type;
 186
 187                 where = (void *)(relocbase + rel->r_offset);
 188
 189                 r_symndx = ELF_R_SYM(rel->r_info);
 190                 r_type = ELF_R_TYPE(rel->r_info);
 191
 192                 switch (r_type & 0xff) {
 193                 case R_TYPE(REL32): {
 194                         const size_t rlen =
 195                             ELF_R_NXTTYPE_64_P(r_type)
 196                                 ? sizeof(Elf_Sxword)
 197                                 : sizeof(Elf_Sword);
 198                         Elf_Sxword old = load_ptr(where, rlen);
 199                         Elf_Sxword val = old;
 200 #if ELFSIZE == 64
 201                         assert(r_type == R_TYPE(REL32)
 202                             || r_type == (R_TYPE(REL32)|(R_TYPE(64) << 8)));
 203 #endif
 204                         assert(r_symndx < gotsym);
 205                         sym = symtab + r_symndx;
 206                         assert(ELF_ST_BIND(sym->st_info) == STB_LOCAL);
 207                         val += relocbase;
 208                         store_ptr(where, val, sizeof(Elf_Sword));
 209                         rdbg(("REL32/L(%p) %p -> %p in <self>",
 210                             where, (void *)old, (void *)val));
 211                         store_ptr(where, val, rlen);
 212                         break;
 213                 }
 214
 215                 case R_TYPE(GPREL32):
 216                 case R_TYPE(NONE):
 217                         break;
 218
 219
 220                 default:
 221                         abort();
 222                 }
 223         }
 224 }
 225
 226 int
 227 _rtld_relocate_nonplt_objects(Obj_Entry *obj)
 228 {
 229         const Elf_Rel *rel;
 230         Elf_Addr *got = obj->pltgot;
 231         const Elf_Sym *sym, *def;
 232         const Obj_Entry *defobj;
 233         Elf_Word i;
 234 #ifdef SUPPORT_OLD_BROKEN_LD
 235         int broken;
 236 #endif
 237
 238 #ifdef SUPPORT_OLD_BROKEN_LD
 239         broken = 0;
 240         sym = obj->symtab;
 241         for (i = 1; i < 12; i++)
 242                 if (sym[i].st_info == ELF_ST_INFO(STB_LOCAL, STT_NOTYPE))
 243                         broken = 1;
 244         dbg(("%s: broken=%d", obj->path, broken));
 245 #endif
 246
 247         i = (got[1] & 0x80000000) ? 2 : 1;
 248         /* Relocate the local GOT entries */
 249         got += i;
 250         for (; i < obj->local_gotno; i++)
 251                 *got++ += (Elf_Addr)obj->relocbase;
 252         sym = obj->symtab + obj->gotsym;
 253         /* Now do the global GOT entries */
 254         for (i = obj->gotsym; i < obj->symtabno; i++) {
 255                 rdbg((" doing got %d sym %p (%s, %lx)", i - obj->gotsym, sym,
 256                     sym->st_name + obj->strtab, (u_long) *got));
 257
 258 #ifdef SUPPORT_OLD_BROKEN_LD
 259                 if (ELF_ST_TYPE(sym->st_info) == STT_FUNC &&
 260                     broken && sym->st_shndx == SHN_UNDEF) {
 261                         /*
 262                          * XXX DANGER WILL ROBINSON!
 263                          * You might think this is stupid, as it intentionally
 264                          * defeats lazy binding -- and you'd be right.
 265                          * Unfortunately, for lazy binding to work right, we
 266                          * need to a way to force the GOT slots used for
 267                          * function pointers to be resolved immediately.  This
 268                          * is supposed to be done automatically by the linker,
 269                          * by not outputting a PLT slot and setting st_value
 270                          * to 0 if there are non-PLT references, but older
 271                          * versions of GNU ld do not do this.
 272                          */
 273                         def = _rtld_find_symdef(i, obj, &defobj, false);
 274                         if (def == NULL)
 275                                 return -1;
 276                         *got = def->st_value + (Elf_Addr)defobj->relocbase;
 277                 } else
 278 #endif
 279                 if (ELF_ST_TYPE(sym->st_info) == STT_FUNC &&
 280                     sym->st_value != 0 && sym->st_shndx == SHN_UNDEF) {
 281                         /*
 282                          * If there are non-PLT references to the function,
 283                          * st_value should be 0, forcing us to resolve the
 284                          * address immediately.
 285                          *
 286                          * XXX DANGER WILL ROBINSON!
 287                          * The linker is not outputting PLT slots for calls to
 288                          * functions that are defined in the same shared
 289                          * library.  This is a bug, because it can screw up
 290                          * link ordering rules if the symbol is defined in
 291                          * more than one module.  For now, if there is a
 292                          * definition, we fail the test above and force a full
 293                          * symbol lookup.  This means that all intra-module
 294                          * calls are bound immediately.  - mycroft, 2003/09/24
 295                          */
 296                         *got = sym->st_value + (Elf_Addr)obj->relocbase;
 297                 } else if (sym->st_info == ELF_ST_INFO(STB_GLOBAL, STT_SECTION)) {
 298                         /* Symbols with index SHN_ABS are not relocated. */
 299                         if (sym->st_shndx != SHN_ABS)
 300                                 *got = sym->st_value +
 301                                     (Elf_Addr)obj->relocbase;
 302                 } else {
 303                         def = _rtld_find_symdef(i, obj, &defobj, false);
 304                         if (def == NULL)
 305                                 return -1;
 306                         *got = def->st_value + (Elf_Addr)defobj->relocbase;
 307                 }
 308
 309                 rdbg(("  --> now %lx", (u_long) *got));
 310                 ++sym;
 311                 ++got;
 312         }
 313
 314         got = obj->pltgot;
 315         for (rel = obj->rel; rel < obj->rellim; rel++) {
 316                 Elf_Word        r_symndx, r_type;
 317                 void            *where;
 318
 319                 where = obj->relocbase + rel->r_offset;
 320                 r_symndx = ELF_R_SYM(rel->r_info);
 321                 r_type = ELF_R_TYPE(rel->r_info);
 322
 323                 switch (r_type & 0xff) {
 324                 case R_TYPE(NONE):
 325                         break;
 326
 327                 case R_TYPE(REL32): {
 328                         /* 32-bit PC-relative reference */
 329                         const size_t rlen =
 330                             ELF_R_NXTTYPE_64_P(r_type)
 331                                 ? sizeof(Elf_Sxword)
 332                                 : sizeof(Elf_Sword);
 333                         Elf_Sxword old = load_ptr(where, rlen);
 334                         Elf_Sxword val = old;
 335
 336                         def = obj->symtab + r_symndx;
 337
 338                         if (r_symndx >= obj->gotsym) {
 339                                 val += got[obj->local_gotno + r_symndx - obj->gotsym];
 340                                 rdbg(("REL32/G(%p) %p --> %p (%s) in %s",
 341                                     where, (void *)old, (void *)val,
 342                                     obj->strtab + def->st_name,
 343                                     obj->path));
 344                         } else {
 345                                 /*
 346                                  * XXX: ABI DIFFERENCE!
 347                                  *
 348                                  * Old NetBSD binutils would generate shared
 349                                  * libs with section-relative relocations being
 350                                  * already adjusted for the start address of
 351                                  * the section.
 352                                  *
 353                                  * New binutils, OTOH, generate shared libs
 354                                  * with the same relocations being based at
 355                                  * zero, so we need to add in the start address
 356                                  * of the section.
 357                                  *
 358                                  * --rkb, Oct 6, 2001
 359                                  */
 360
 361                                 if (def->st_info ==
 362                                     ELF_ST_INFO(STB_LOCAL, STT_SECTION)
 363 #ifdef SUPPORT_OLD_BROKEN_LD
 364                                     && !broken
 365 #endif
 366                                     )
 367                                         val += (Elf_Addr)def->st_value;
 368
 369                                 val += (Elf_Addr)obj->relocbase;
 370
 371                                 rdbg(("REL32/L(%p) %p -> %p (%s) in %s",
 372                                     where, (void *)old, (void *)val,
 373                                     obj->strtab + def->st_name, obj->path));
 374                         }
 375                         store_ptr(where, val, rlen);
 376                         break;
 377                 }
 378
 379 #if ELFSIZE == 64
 380                 case R_TYPE(TLS_DTPMOD64):
 381 #else
 382                 case R_TYPE(TLS_DTPMOD32):
 383 #endif
 384                 {
 385                         Elf_Addr old = load_ptr(where, ELFSIZE / 8);
 386                         Elf_Addr val = old;
 387
 388                         def = _rtld_find_symdef(r_symndx, obj, &defobj, false);
 389                         if (def == NULL)
 390                                 return -1;
 391
 392                         val += (Elf_Addr)defobj->tlsindex;
 393
 394                         store_ptr(where, val, ELFSIZE / 8);
 395                         rdbg(("DTPMOD %s in %s --> %p in %s",
 396                             obj->strtab + obj->symtab[r_symndx].st_name,
 397                             obj->path, (void *)old, defobj->path));
 398                         break;
 399                 }
 400
 401 #if ELFSIZE == 64
 402                 case R_TYPE(TLS_DTPREL64):
 403 #else
 404                 case R_TYPE(TLS_DTPREL32):
 405 #endif
 406                 {
 407                         Elf_Addr old = load_ptr(where, ELFSIZE / 8);
 408                         Elf_Addr val = old;
 409
 410                         def = _rtld_find_symdef(r_symndx, obj, &defobj, false);
 411                         if (def == NULL)
 412                                 return -1;
 413
 414                         if (!defobj->tls_done && _rtld_tls_offset_allocate(obj))
 415                                 return -1;
 416
 417                         val += (Elf_Addr)def->st_value - TLS_DTV_OFFSET;
 418                         store_ptr(where, val, ELFSIZE / 8);
 419
 420                         rdbg(("DTPREL %s in %s --> %p in %s",
 421                             obj->strtab + obj->symtab[r_symndx].st_name,
 422                             obj->path, (void *)old, defobj->path));
 423                         break;
 424                 }
 425
 426 #if ELFSIZE == 64
 427                 case R_TYPE(TLS_TPREL64):
 428 #else
 429                 case R_TYPE(TLS_TPREL32):
 430 #endif
 431                 {
 432                         Elf_Addr old = load_ptr(where, ELFSIZE / 8);
 433                         Elf_Addr val = old;
 434
 435                         def = _rtld_find_symdef(r_symndx, obj, &defobj, false);
 436                         if (def == NULL)
 437                                 return -1;
 438
 439                         if (!defobj->tls_done && _rtld_tls_offset_allocate(obj))
 440                                 return -1;
 441
 442                         val += (Elf_Addr)(def->st_value + defobj->tlsoffset
 443                             - TLS_TP_OFFSET);
 444                         store_ptr(where, val, ELFSIZE / 8);
 445
 446                         rdbg(("TPREL %s in %s --> %p in %s",
 447                             obj->strtab + obj->symtab[r_symndx].st_name,
 448                             obj->path, (void *)*where, defobj->path));
 449                         break;
 450                 }
 451
 452                 default:
 453                         rdbg(("sym = %lu, type = %lu, offset = %p, "
 454                             "contents = %p, symbol = %s",
 455                             (u_long)r_symndx, (u_long)ELF_R_TYPE(rel->r_info),
 456                             (void *)rel->r_offset,
 457                             (void *)load_ptr(where, sizeof(Elf_Sword)),
 458                             obj->strtab + obj->symtab[r_symndx].st_name));
 459                         _rtld_error("%s: Unsupported relocation type %ld "
 460                             "in non-PLT relocations",
 461                             obj->path, (u_long) ELF_R_TYPE(rel->r_info));
 462                         return -1;
 463                 }
 464         }
 465
 466         return 0;
 467 }
 468
 469 int
 470 _rtld_relocate_plt_lazy(const Obj_Entry *obj)
 471 {
 472         /* PLT fixups were done above in the GOT relocation. */
 473         return 0;
 474 }
 475
 476 static inline int
 477 _rtld_relocate_plt_object(const Obj_Entry *obj, Elf_Word sym, Elf_Addr *tp)
 478 {
 479         Elf_Addr *got = obj->pltgot;
 480         const Elf_Sym *def;
 481         const Obj_Entry *defobj;
 482         Elf_Addr new_value;
 483
 484         def = _rtld_find_plt_symdef(sym, obj, &defobj, tp != NULL);
 485         if (__predict_false(def == NULL))
 486                 return -1;
 487         if (__predict_false(def == &_rtld_sym_zero))
 488                 return 0;
 489
 490         if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
 491                 if (tp == NULL)
 492                         return 0;
 493                 new_value = _rtld_resolve_ifunc(defobj, def);
 494         } else {
 495                 new_value = (Elf_Addr)(defobj->relocbase + def->st_value);
 496         }
 497         rdbg(("bind now/fixup in %s --> new=%p",
 498             defobj->strtab + def->st_name, (void *)new_value));
 499         got[obj->local_gotno + sym - obj->gotsym] = new_value;
 500
 501         if (tp)
 502                 *tp = new_value;
 503         return 0;
 504 }
 505
 506 caddr_t
 507 _rtld_bind(Elf_Word a0, Elf_Addr a1, Elf_Addr a2, Elf_Addr a3)
 508 {
 509         Elf_Addr *got = (Elf_Addr *)(a2 - 0x7ff0);
 510         const Obj_Entry *obj = (Obj_Entry *)(got[1] & GOT1_MASK);
 511         Elf_Addr new_value = 0; /* XXX gcc */
 512         int err;
 513
 514         _rtld_shared_enter();
 515         err = _rtld_relocate_plt_object(obj, a0, &new_value);
 516         if (err)
 517                 _rtld_die();
 518         _rtld_shared_exit();
 519
 520         return (caddr_t)new_value;
 521 }
 522
 523 int
 524 _rtld_relocate_plt_objects(const Obj_Entry *obj)
 525 {
 526         const Elf_Sym *sym = obj->symtab + obj->gotsym;
 527         Elf_Word i;
 528
 529         for (i = obj->gotsym; i < obj->symtabno; i++, sym++) {
 530                 if (ELF_ST_TYPE(sym->st_info) == STT_FUNC)
 531                         if (_rtld_relocate_plt_object(obj, i, NULL) < 0)
 532                                 return -1;
 533         }
 534
 535         return 0;
 536 }