libexec/rtld-elf/mips/reloc.c

   1 /*      $NetBSD: mips_reloc.c,v 1.58 2010/01/14 11:57:06 skrll 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 __FBSDID("$FreeBSD$");
  33
  34 #include <sys/types.h>
  35 #include <sys/stat.h>
  36 #include <sys/endian.h>
  37
  38 #include <stdlib.h>
  39 #include <string.h>
  40
  41 #include "debug.h"
  42 #include "rtld.h"
  43
  44 #ifdef __mips_n64
  45 #define GOT1_MASK       0x8000000000000000UL
  46 #else
  47 #define GOT1_MASK       0x80000000UL
  48 #endif
  49
  50 void
  51 init_pltgot(Obj_Entry *obj)
  52 {
  53         if (obj->pltgot != NULL) {
  54                 obj->pltgot[0] = (Elf_Addr) &_rtld_bind_start;
  55                 if (obj->pltgot[1] & 0x80000000)
  56                         obj->pltgot[1] = (Elf_Addr) obj | GOT1_MASK;
  57         }
  58 }
  59
  60 int
  61 do_copy_relocations(Obj_Entry *dstobj)
  62 {
  63         /* Do nothing */
  64         return 0;
  65 }
  66
  67 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
  68
  69 /*
  70  * It is possible for the compiler to emit relocations for unaligned data.
  71  * We handle this situation with these inlines.
  72  */
  73 #ifdef __mips_n64
  74 /*
  75  * ELF64 MIPS encodes the relocs uniquely.  The first 32-bits of info contain
  76  * the symbol index.  The top 32-bits contain three relocation types encoded
  77  * in big-endian integer with first relocation in LSB.  This means for little
  78  * endian we have to byte swap that integer (r_type).
  79  */
  80 #define Elf_Sxword                      Elf64_Sxword
  81 #define ELF_R_NXTTYPE_64_P(r_type)      ((((r_type) >> 8) & 0xff) == R_TYPE(64))
  82 #if BYTE_ORDER == LITTLE_ENDIAN
  83 #undef ELF_R_SYM
  84 #undef ELF_R_TYPE
  85 #define ELF_R_SYM(r_info)               ((r_info) & 0xffffffff)
  86 #define ELF_R_TYPE(r_info)              bswap32(((r_info) >> 32))
  87 #endif
  88 #else
  89 #define ELF_R_NXTTYPE_64_P(r_type)      (0)
  90 #define Elf_Sxword                      Elf32_Sword
  91 #endif
  92
  93 static __inline Elf_Sxword
  94 load_ptr(void *where, size_t len)
  95 {
  96         Elf_Sxword val;
  97
  98         if (__predict_true(((uintptr_t)where & (len - 1)) == 0)) {
  99 #ifdef __mips_n64
 100                 if (len == sizeof(Elf_Sxword))
 101                         return *(Elf_Sxword *)where;
 102 #endif
 103                 return *(Elf_Sword *)where;
 104         }
 105
 106         val = 0;
 107 #if BYTE_ORDER == LITTLE_ENDIAN
 108         (void)memcpy(&val, where, len);
 109 #endif
 110 #if BYTE_ORDER == BIG_ENDIAN
 111         (void)memcpy((uint8_t *)((&val)+1) - len, where, len);
 112 #endif
 113         return (len == sizeof(Elf_Sxword)) ? val : (Elf_Sword)val;
 114 }
 115
 116 static __inline void
 117 store_ptr(void *where, Elf_Sxword val, size_t len)
 118 {
 119         if (__predict_true(((uintptr_t)where & (len - 1)) == 0)) {
 120 #ifdef __mips_n64
 121                 if (len == sizeof(Elf_Sxword)) {
 122                         *(Elf_Sxword *)where = val;
 123                         return;
 124                 }
 125 #endif
 126                 *(Elf_Sword *)where = val;
 127                 return;
 128         }
 129 #if BYTE_ORDER == LITTLE_ENDIAN
 130         (void)memcpy(where, &val, len);
 131 #endif
 132 #if BYTE_ORDER == BIG_ENDIAN
 133         (void)memcpy(where, (const uint8_t *)((&val)+1) - len, len);
 134 #endif
 135 }
 136
 137 void
 138 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
 139 {
 140         const Elf_Rel *rel = 0, *rellim;
 141         Elf_Addr relsz = 0;
 142         const Elf_Sym *symtab = NULL, *sym;
 143         Elf_Addr *where;
 144         Elf_Addr *got = NULL;
 145         Elf_Word local_gotno = 0, symtabno = 0, gotsym = 0;
 146         size_t i;
 147
 148         for (; dynp->d_tag != DT_NULL; dynp++) {
 149                 switch (dynp->d_tag) {
 150                 case DT_REL:
 151                         rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr);
 152                         break;
 153                 case DT_RELSZ:
 154                         relsz = dynp->d_un.d_val;
 155                         break;
 156                 case DT_SYMTAB:
 157                         symtab = (const Elf_Sym *)(relocbase + dynp->d_un.d_ptr);
 158                         break;
 159                 case DT_PLTGOT:
 160                         got = (Elf_Addr *)(relocbase + dynp->d_un.d_ptr);
 161                         break;
 162                 case DT_MIPS_LOCAL_GOTNO:
 163                         local_gotno = dynp->d_un.d_val;
 164                         break;
 165                 case DT_MIPS_SYMTABNO:
 166                         symtabno = dynp->d_un.d_val;
 167                         break;
 168                 case DT_MIPS_GOTSYM:
 169                         gotsym = dynp->d_un.d_val;
 170                         break;
 171                 }
 172         }
 173
 174         i = (got[1] & GOT1_MASK) ? 2 : 1;
 175         /* Relocate the local GOT entries */
 176         got += i;
 177         for (; i < local_gotno; i++) {
 178                 *got++ += relocbase;
 179         }
 180
 181         sym = symtab + gotsym;
 182         /* Now do the global GOT entries */
 183         for (i = gotsym; i < symtabno; i++) {
 184                 *got = sym->st_value + relocbase;
 185                 ++sym;
 186                 ++got;
 187         }
 188
 189         rellim = (const Elf_Rel *)((caddr_t)rel + relsz);
 190         for (; rel < rellim; rel++) {
 191                 Elf_Word r_symndx, r_type;
 192
 193                 where = (void *)(relocbase + rel->r_offset);
 194
 195                 r_symndx = ELF_R_SYM(rel->r_info);
 196                 r_type = ELF_R_TYPE(rel->r_info);
 197
 198                 switch (r_type & 0xff) {
 199                 case R_TYPE(REL32): {
 200                         const size_t rlen =
 201                             ELF_R_NXTTYPE_64_P(r_type)
 202                                 ? sizeof(Elf_Sxword)
 203                                 : sizeof(Elf_Sword);
 204                         Elf_Sxword old = load_ptr(where, rlen);
 205                         Elf_Sxword val = old;
 206 #ifdef __mips_n64
 207                         assert(r_type == R_TYPE(REL32)
 208                             || r_type == (R_TYPE(REL32)|(R_TYPE(64) << 8)));
 209 #endif
 210                         assert(r_symndx < gotsym);
 211                         sym = symtab + r_symndx;
 212                         assert(ELF_ST_BIND(sym->st_info) == STB_LOCAL);
 213                         val += relocbase;
 214                         store_ptr(where, val, sizeof(Elf_Sword));
 215                         dbg("REL32/L(%p) %p -> %p in <self>",
 216                             where, (void *)old, (void *)val);
 217                         store_ptr(where, val, rlen);
 218                         break;
 219                 }
 220
 221                 case R_TYPE(GPREL32):
 222                 case R_TYPE(NONE):
 223                         break;
 224
 225
 226                 default:
 227                         abort();
 228                         break;
 229                 }
 230         }
 231 }
 232
 233 Elf_Addr
 234 _mips_rtld_bind(Obj_Entry *obj, Elf_Size reloff)
 235 {
 236         Elf_Addr *got = obj->pltgot;
 237         const Elf_Sym *def;
 238         const Obj_Entry *defobj;
 239         Elf_Addr target;
 240
 241         def = find_symdef(reloff, obj, &defobj, SYMLOOK_IN_PLT, NULL);
 242         if (def == NULL)
 243                 _rtld_error("bind failed no symbol");
 244
 245         target = (Elf_Addr)(defobj->relocbase + def->st_value);
 246         dbg("bind now/fixup at %s sym # %d in %s --> was=%p new=%p",
 247             obj->path,
 248             reloff, defobj->strtab + def->st_name,
 249             (void *)got[obj->local_gotno + reloff - obj->gotsym],
 250             (void *)target);
 251         got[obj->local_gotno + reloff - obj->gotsym] = target;
 252         return (Elf_Addr)target;
 253 }
 254
 255 int
 256 reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld)
 257 {
 258         const Elf_Rel *rel;
 259         const Elf_Rel *rellim;
 260         Elf_Addr *got = obj->pltgot;
 261         const Elf_Sym *sym, *def;
 262         const Obj_Entry *defobj;
 263         Elf_Word i;
 264 #ifdef SUPPORT_OLD_BROKEN_LD
 265         int broken;
 266 #endif
 267
 268         /* The relocation for the dynamic loader has already been done. */
 269         if (obj == obj_rtld)
 270                 return (0);
 271
 272 #ifdef SUPPORT_OLD_BROKEN_LD
 273         broken = 0;
 274         sym = obj->symtab;
 275         for (i = 1; i < 12; i++)
 276                 if (sym[i].st_info == ELF_ST_INFO(STB_LOCAL, STT_NOTYPE))
 277                         broken = 1;
 278         dbg("%s: broken=%d", obj->path, broken);
 279 #endif
 280
 281         i = (got[1] & GOT1_MASK) ? 2 : 1;
 282
 283         /* Relocate the local GOT entries */
 284         got += i;
 285         dbg("got:%p for %d entries adding %x",
 286             got, obj->local_gotno, (uint32_t)obj->relocbase);
 287         for (; i < obj->local_gotno; i++) {
 288                 *got += (Elf_Addr)obj->relocbase;
 289                 got++;
 290         }
 291         sym = obj->symtab + obj->gotsym;
 292
 293         dbg("got:%p for %d entries",
 294             got, obj->symtabno);
 295         /* Now do the global GOT entries */
 296         for (i = obj->gotsym; i < obj->symtabno; i++) {
 297                 dbg(" doing got %d sym %p (%s, %lx)", i - obj->gotsym, sym,
 298                     sym->st_name + obj->strtab, (u_long) *got);
 299
 300 #ifdef SUPPORT_OLD_BROKEN_LD
 301                 if (ELF_ST_TYPE(sym->st_info) == STT_FUNC &&
 302                     broken && sym->st_shndx == SHN_UNDEF) {
 303                         /*
 304                          * XXX DANGER WILL ROBINSON!
 305                          * You might think this is stupid, as it intentionally
 306                          * defeats lazy binding -- and you'd be right.
 307                          * Unfortunately, for lazy binding to work right, we
 308                          * need to a way to force the GOT slots used for
 309                          * function pointers to be resolved immediately.  This
 310                          * is supposed to be done automatically by the linker,
 311                          * by not outputting a PLT slot and setting st_value
 312                          * to 0 if there are non-PLT references, but older
 313                          * versions of GNU ld do not do this.
 314                          */
 315                         def = find_symdef(i, obj, &defobj, false, NULL);
 316                         if (def == NULL)
 317                                 return -1;
 318                         *got = def->st_value + (Elf_Addr)defobj->relocbase;
 319                 } else
 320 #endif
 321                 if (ELF_ST_TYPE(sym->st_info) == STT_FUNC &&
 322                     sym->st_value != 0 && sym->st_shndx == SHN_UNDEF) {
 323                         /*
 324                          * If there are non-PLT references to the function,
 325                          * st_value should be 0, forcing us to resolve the
 326                          * address immediately.
 327                          *
 328                          * XXX DANGER WILL ROBINSON!
 329                          * The linker is not outputting PLT slots for calls to
 330                          * functions that are defined in the same shared
 331                          * library.  This is a bug, because it can screw up
 332                          * link ordering rules if the symbol is defined in
 333                          * more than one module.  For now, if there is a
 334                          * definition, we fail the test above and force a full
 335                          * symbol lookup.  This means that all intra-module
 336                          * calls are bound immediately.  - mycroft, 2003/09/24
 337                          */
 338                         *got = sym->st_value + (Elf_Addr)obj->relocbase;
 339                         if ((Elf_Addr)(*got) == (Elf_Addr)obj->relocbase) {
 340                                 dbg("Warning2, i:%d maps to relocbase address:%x",
 341                                     i, (uint32_t)obj->relocbase);
 342                         }
 343
 344                 } else if (sym->st_info == ELF_ST_INFO(STB_GLOBAL, STT_SECTION)) {
 345                         /* Symbols with index SHN_ABS are not relocated. */
 346                         if (sym->st_shndx != SHN_ABS) {
 347                                 *got = sym->st_value +
 348                                     (Elf_Addr)obj->relocbase;
 349                                 if ((Elf_Addr)(*got) == (Elf_Addr)obj->relocbase) {
 350                                         dbg("Warning3, i:%d maps to relocbase address:%x",
 351                                             i, (uint32_t)obj->relocbase);
 352                                 }
 353                         }
 354                 } else {
 355                         /* TODO: add cache here */
 356                         def = find_symdef(i, obj, &defobj, false, NULL);
 357                         if (def == NULL) {
 358                                 dbg("Warning4, cant find symbole %d", i);
 359                                 return -1;
 360                         }
 361                         *got = def->st_value + (Elf_Addr)defobj->relocbase;
 362                         if ((Elf_Addr)(*got) == (Elf_Addr)obj->relocbase) {
 363                                 dbg("Warning4, i:%d maps to relocbase address:%x",
 364                                     i, (uint32_t)obj->relocbase);
 365                                 dbg("via first obj symbol %s",
 366                                     obj->strtab + obj->symtab[i].st_name);
 367                                 dbg("found in obj %p:%s",
 368                                     defobj, defobj->path);
 369                         }
 370                 }
 371
 372                 dbg("  --> now %lx", (u_long) *got);
 373                 ++sym;
 374                 ++got;
 375         }
 376
 377         got = obj->pltgot;
 378         rellim = (const Elf_Rel *)((caddr_t)obj->rel + obj->relsize);
 379         for (rel = obj->rel; rel < rellim; rel++) {
 380                 Elf_Word        r_symndx, r_type;
 381                 void            *where;
 382
 383                 where = obj->relocbase + rel->r_offset;
 384                 r_symndx = ELF_R_SYM(rel->r_info);
 385                 r_type = ELF_R_TYPE(rel->r_info);
 386
 387                 switch (r_type & 0xff) {
 388                 case R_TYPE(NONE):
 389                         break;
 390
 391                 case R_TYPE(REL32): {
 392                         /* 32-bit PC-relative reference */
 393                         const size_t rlen =
 394                             ELF_R_NXTTYPE_64_P(r_type)
 395                                 ? sizeof(Elf_Sxword)
 396                                 : sizeof(Elf_Sword);
 397                         Elf_Sxword old = load_ptr(where, rlen);
 398                         Elf_Sxword val = old;
 399
 400                         def = obj->symtab + r_symndx;
 401
 402                         if (r_symndx >= obj->gotsym) {
 403                                 val += got[obj->local_gotno + r_symndx - obj->gotsym];
 404                                 dbg("REL32/G(%p) %p --> %p (%s) in %s",
 405                                     where, (void *)old, (void *)val,
 406                                     obj->strtab + def->st_name,
 407                                     obj->path);
 408                         } else {
 409                                 /*
 410                                  * XXX: ABI DIFFERENCE!
 411                                  *
 412                                  * Old NetBSD binutils would generate shared
 413                                  * libs with section-relative relocations being
 414                                  * already adjusted for the start address of
 415                                  * the section.
 416                                  *
 417                                  * New binutils, OTOH, generate shared libs
 418                                  * with the same relocations being based at
 419                                  * zero, so we need to add in the start address
 420                                  * of the section.
 421                                  *
 422                                  * --rkb, Oct 6, 2001
 423                                  */
 424
 425                                 if (def->st_info ==
 426                                     ELF_ST_INFO(STB_LOCAL, STT_SECTION)
 427 #ifdef SUPPORT_OLD_BROKEN_LD
 428                                     && !broken
 429 #endif
 430                                     )
 431                                         val += (Elf_Addr)def->st_value;
 432
 433                                 val += (Elf_Addr)obj->relocbase;
 434
 435                                 dbg("REL32/L(%p) %p -> %p (%s) in %s",
 436                                     where, (void *)old, (void *)val,
 437                                     obj->strtab + def->st_name, obj->path);
 438                         }
 439                         store_ptr(where, val, rlen);
 440                         break;
 441                 }
 442
 443                 default:
 444                         dbg("sym = %lu, type = %lu, offset = %p, "
 445                             "contents = %p, symbol = %s",
 446                             (u_long)r_symndx, (u_long)ELF_R_TYPE(rel->r_info),
 447                             (void *)rel->r_offset,
 448                             (void *)load_ptr(where, sizeof(Elf_Sword)),
 449                             obj->strtab + obj->symtab[r_symndx].st_name);
 450                         _rtld_error("%s: Unsupported relocation type %ld "
 451                             "in non-PLT relocations",
 452                             obj->path, (u_long) ELF_R_TYPE(rel->r_info));
 453                         return -1;
 454                 }
 455         }
 456
 457         return 0;
 458 }
 459
 460 /*
 461  *  Process the PLT relocations.
 462  */
 463 int
 464 reloc_plt(Obj_Entry *obj)
 465 {
 466 #if 0
 467         const Elf_Rel *rellim;
 468         const Elf_Rel *rel;
 469
 470         dbg("reloc_plt obj:%p pltrel:%p sz:%d", obj, obj->pltrel, (int)obj->pltrelsize);
 471         dbg("gottable %p num syms:%d", obj->pltgot, obj->symtabno );
 472         dbg("*****************************************************");
 473         rellim = (const Elf_Rel *)((char *)obj->pltrel +
 474             obj->pltrelsize);
 475         for (rel = obj->pltrel;  rel < rellim;  rel++) {
 476                 Elf_Addr *where;
 477                 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
 478                 *where += (Elf_Addr )obj->relocbase;
 479         }
 480
 481 #endif
 482         /* PLT fixups were done above in the GOT relocation. */
 483         return (0);
 484 }
 485
 486 /*
 487  * LD_BIND_NOW was set - force relocation for all jump slots
 488  */
 489 int
 490 reloc_jmpslots(Obj_Entry *obj)
 491 {
 492         /* Do nothing */
 493         obj->jmpslots_done = true;
 494
 495         return (0);
 496 }
 497
 498 Elf_Addr
 499 reloc_jmpslot(Elf_Addr *where, Elf_Addr target, const Obj_Entry *defobj,
 500                 const Obj_Entry *obj, const Elf_Rel *rel)
 501 {
 502
 503         /* Do nothing */
 504
 505         return target;
 506 }
 507
 508 void
 509 allocate_initial_tls(Obj_Entry *objs)
 510 {
 511
 512 }
 513
 514 void *
 515 __tls_get_addr(tls_index* ti)
 516 {
 517         return (NULL);
 518 }