mdreloc.c revision 1.47
1/* $NetBSD: mdreloc.c,v 1.47 2011/03/31 12:47:01 nakayama Exp $ */ 2 3/*- 4 * Copyright (c) 1999, 2002 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Paul Kranenburg and by Charles M. Hannum. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32#include <sys/cdefs.h> 33#ifndef lint 34__RCSID("$NetBSD: mdreloc.c,v 1.47 2011/03/31 12:47:01 nakayama Exp $"); 35#endif /* not lint */ 36 37#include <errno.h> 38#include <stdio.h> 39#include <stdlib.h> 40#include <string.h> 41#include <unistd.h> 42 43#include "rtldenv.h" 44#include "debug.h" 45#include "rtld.h" 46 47/* 48 * The following table holds for each relocation type: 49 * - the width in bits of the memory location the relocation 50 * applies to (not currently used) 51 * - the number of bits the relocation value must be shifted to the 52 * right (i.e. discard least significant bits) to fit into 53 * the appropriate field in the instruction word. 54 * - flags indicating whether 55 * * the relocation involves a symbol 56 * * the relocation is relative to the current position 57 * * the relocation is for a GOT entry 58 * * the relocation is relative to the load address 59 * 60 */ 61#define _RF_S 0x80000000 /* Resolve symbol */ 62#define _RF_A 0x40000000 /* Use addend */ 63#define _RF_P 0x20000000 /* Location relative */ 64#define _RF_G 0x10000000 /* GOT offset */ 65#define _RF_B 0x08000000 /* Load address relative */ 66#define _RF_U 0x04000000 /* Unaligned */ 67#define _RF_SZ(s) (((s) & 0xff) << 8) /* memory target size */ 68#define _RF_RS(s) ( (s) & 0xff) /* right shift */ 69static const int reloc_target_flags[R_TYPE(TLS_TPOFF64)+1] = { 70 0, /* NONE */ 71 _RF_S|_RF_A| _RF_SZ(8) | _RF_RS(0), /* RELOC_8 */ 72 _RF_S|_RF_A| _RF_SZ(16) | _RF_RS(0), /* RELOC_16 */ 73 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* RELOC_32 */ 74 _RF_S|_RF_A|_RF_P| _RF_SZ(8) | _RF_RS(0), /* DISP_8 */ 75 _RF_S|_RF_A|_RF_P| _RF_SZ(16) | _RF_RS(0), /* DISP_16 */ 76 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* DISP_32 */ 77 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WDISP_30 */ 78 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WDISP_22 */ 79 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(10), /* HI22 */ 80 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 22 */ 81 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 13 */ 82 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* LO10 */ 83 _RF_G| _RF_SZ(32) | _RF_RS(0), /* GOT10 */ 84 _RF_G| _RF_SZ(32) | _RF_RS(0), /* GOT13 */ 85 _RF_G| _RF_SZ(32) | _RF_RS(10), /* GOT22 */ 86 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* PC10 */ 87 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(10), /* PC22 */ 88 _RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WPLT30 */ 89 _RF_SZ(32) | _RF_RS(0), /* COPY */ 90 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* GLOB_DAT */ 91 _RF_SZ(32) | _RF_RS(0), /* JMP_SLOT */ 92 _RF_A| _RF_B| _RF_SZ(32) | _RF_RS(0), /* RELATIVE */ 93 _RF_S|_RF_A| _RF_U| _RF_SZ(32) | _RF_RS(0), /* UA_32 */ 94 95 /* TLS and 64 bit relocs not listed here... */ 96}; 97 98#ifdef RTLD_DEBUG_RELOC 99static const char *reloc_names[] = { 100 "NONE", "RELOC_8", "RELOC_16", "RELOC_32", "DISP_8", 101 "DISP_16", "DISP_32", "WDISP_30", "WDISP_22", "HI22", 102 "22", "13", "LO10", "GOT10", "GOT13", 103 "GOT22", "PC10", "PC22", "WPLT30", "COPY", 104 "GLOB_DAT", "JMP_SLOT", "RELATIVE", "UA_32", 105 106 /* not used with 32bit userland, besides a few of the TLS ones */ 107 "PLT32", 108 "HIPLT22", "LOPLT10", "LOPLT10", "PCPLT22", "PCPLT32", 109 "10", "11", "64", "OLO10", "HH22", 110 "HM10", "LM22", "PC_HH22", "PC_HM10", "PC_LM22", 111 "WDISP16", "WDISP19", "GLOB_JMP", "7", "5", "6", 112 "DISP64", "PLT64", "HIX22", "LOX10", "H44", "M44", 113 "L44", "REGISTER", "UA64", "UA16", 114 "TLS_GD_HI22", "TLS_GD_LO10", "TLS_GD_ADD", "TLS_GD_CALL", 115 "TLS_LDM_HI22", "TLS_LDM_LO10", "TLS_LDM_ADD", "TLS_LDM_CALL", 116 "TLS_LDO_HIX22", "TLS_LDO_LOX10", "TLS_LDO_ADD", "TLS_IE_HI22", 117 "TLS_IE_LO10", "TLS_IE_LD", "TLS_IE_LDX", "TLS_IE_ADD", "TLS_LE_HIX22", 118 "TLS_LE_LOX10", "TLS_DTPMOD32", "TLS_DTPMOD64", "TLS_DTPOFF32", 119 "TLS_DTPOFF64", "TLS_TPOFF32", "TLS_TPOFF64", 120}; 121#endif 122 123#define RELOC_RESOLVE_SYMBOL(t) ((reloc_target_flags[t] & _RF_S) != 0) 124#define RELOC_PC_RELATIVE(t) ((reloc_target_flags[t] & _RF_P) != 0) 125#define RELOC_BASE_RELATIVE(t) ((reloc_target_flags[t] & _RF_B) != 0) 126#define RELOC_UNALIGNED(t) ((reloc_target_flags[t] & _RF_U) != 0) 127#define RELOC_USE_ADDEND(t) ((reloc_target_flags[t] & _RF_A) != 0) 128#define RELOC_TARGET_SIZE(t) ((reloc_target_flags[t] >> 8) & 0xff) 129#define RELOC_VALUE_RIGHTSHIFT(t) (reloc_target_flags[t] & 0xff) 130#define RELOC_TLS(t) (t >= R_TYPE(TLS_GD_HI22)) 131 132static const int reloc_target_bitmask[] = { 133#define _BM(x) (~(-(1ULL << (x)))) 134 0, /* NONE */ 135 _BM(8), _BM(16), _BM(32), /* RELOC_8, _16, _32 */ 136 _BM(8), _BM(16), _BM(32), /* DISP8, DISP16, DISP32 */ 137 _BM(30), _BM(22), /* WDISP30, WDISP22 */ 138 _BM(22), _BM(22), /* HI22, _22 */ 139 _BM(13), _BM(10), /* RELOC_13, _LO10 */ 140 _BM(10), _BM(13), _BM(22), /* GOT10, GOT13, GOT22 */ 141 _BM(10), _BM(22), /* _PC10, _PC22 */ 142 _BM(30), 0, /* _WPLT30, _COPY */ 143 -1, -1, -1, /* _GLOB_DAT, JMP_SLOT, _RELATIVE */ 144 _BM(32) /* _UA32 */ 145#undef _BM 146}; 147#define RELOC_VALUE_BITMASK(t) (reloc_target_bitmask[t]) 148 149void _rtld_bind_start(void); 150void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 151caddr_t _rtld_bind(const Obj_Entry *, Elf_Word); 152static inline int _rtld_relocate_plt_object(const Obj_Entry *, 153 const Elf_Rela *, Elf_Addr *); 154 155void 156_rtld_setup_pltgot(const Obj_Entry *obj) 157{ 158 /* 159 * PLTGOT is the PLT on the sparc. 160 * The first entry holds the call the dynamic linker. 161 * We construct a `call' sequence that transfers 162 * to `_rtld_bind_start()'. 163 * The second entry holds the object identification. 164 * Note: each PLT entry is three words long. 165 */ 166#define SAVE 0x9de3bfa0 /* i.e. `save %sp,-96,%sp' */ 167#define CALL 0x40000000 168#define NOP 0x01000000 169 obj->pltgot[0] = SAVE; 170 obj->pltgot[1] = CALL | 171 ((Elf_Addr) &_rtld_bind_start - (Elf_Addr) &obj->pltgot[1]) >> 2; 172 obj->pltgot[2] = NOP; 173 obj->pltgot[3] = (Elf_Addr) obj; 174} 175 176void 177_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 178{ 179 const Elf_Rela *rela = 0, *relalim; 180 Elf_Addr relasz = 0; 181 Elf_Addr *where; 182 183 for (; dynp->d_tag != DT_NULL; dynp++) { 184 switch (dynp->d_tag) { 185 case DT_RELA: 186 rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr); 187 break; 188 case DT_RELASZ: 189 relasz = dynp->d_un.d_val; 190 break; 191 } 192 } 193 relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz); 194 for (; rela < relalim; rela++) { 195 where = (Elf_Addr *)(relocbase + rela->r_offset); 196 *where += (Elf_Addr)(relocbase + rela->r_addend); 197 } 198} 199 200int 201_rtld_relocate_nonplt_objects(Obj_Entry *obj) 202{ 203 const Elf_Rela *rela; 204 205 for (rela = obj->rela; rela < obj->relalim; rela++) { 206 Elf_Addr *where; 207 Elf_Word type, value, mask; 208 const Elf_Sym *def = NULL; 209 const Obj_Entry *defobj = NULL; 210 unsigned long symnum; 211 212 where = (Elf_Addr *) (obj->relocbase + rela->r_offset); 213 symnum = ELF_R_SYM(rela->r_info); 214 215 type = ELF_R_TYPE(rela->r_info); 216 if (type == R_TYPE(NONE)) 217 continue; 218 219 /* We do JMP_SLOTs in _rtld_bind() below */ 220 if (type == R_TYPE(JMP_SLOT)) 221 continue; 222 223 /* COPY relocs are also handled elsewhere */ 224 if (type == R_TYPE(COPY)) 225 continue; 226 227 /* 228 * We use the fact that relocation types are an `enum' 229 * Note: R_SPARC_TLS_TPOFF64 is currently numerically largest. 230 */ 231 if (type > R_TYPE(TLS_TPOFF64)) 232 return (-1); 233 234 value = rela->r_addend; 235 236 /* 237 * Handle TLS relocations here, they are different. 238 */ 239 if (RELOC_TLS(type)) { 240 switch (type) { 241 case R_TYPE(TLS_DTPMOD32): 242 def = _rtld_find_symdef(symnum, obj, 243 &defobj, false); 244 if (def == NULL) 245 return -1; 246 247 *where = (Elf_Addr)defobj->tlsindex; 248 249 rdbg(("TLS_DTPMOD32 %s in %s --> %p", 250 obj->strtab + 251 obj->symtab[symnum].st_name, 252 obj->path, (void *)*where)); 253 254 break; 255 256 case R_TYPE(TLS_DTPOFF32): 257 def = _rtld_find_symdef(symnum, obj, 258 &defobj, false); 259 if (def == NULL) 260 return -1; 261 262 *where = (Elf_Addr)(def->st_value 263 + rela->r_addend); 264 265 rdbg(("TLS_DTPOFF32 %s in %s --> %p", 266 obj->strtab + 267 obj->symtab[symnum].st_name, 268 obj->path, (void *)*where)); 269 270 break; 271 272 case R_TYPE(TLS_TPOFF32): 273 def = _rtld_find_symdef(symnum, obj, 274 &defobj, false); 275 if (def == NULL) 276 return -1; 277 278 if (!defobj->tls_done && 279 _rtld_tls_offset_allocate(obj)) 280 return -1; 281 282 *where = (Elf_Addr)(def->st_value - 283 defobj->tlsoffset + 284 rela->r_addend); 285 286 rdbg(("TLS_TPOFF32 %s in %s --> %p", 287 obj->strtab + 288 obj->symtab[symnum].st_name, 289 obj->path, (void *)*where)); 290 291 break; 292 } 293 continue; 294 } 295 296 /* 297 * If it is no TLS relocation (handled above), we can not 298 * deal with it if it is beyound R_SPARC_6. 299 */ 300 if (type > R_TYPE(6)) 301 return (-1); 302 303 /* 304 * Handle relative relocs here, as an optimization. 305 */ 306 if (type == R_TYPE(RELATIVE)) { 307 *where += (Elf_Addr)(obj->relocbase + value); 308 rdbg(("RELATIVE in %s --> %p", obj->path, 309 (void *)*where)); 310 continue; 311 } 312 313 if (RELOC_RESOLVE_SYMBOL(type)) { 314 315 /* Find the symbol */ 316 def = _rtld_find_symdef(symnum, obj, &defobj, false); 317 if (def == NULL) 318 return (-1); 319 320 /* Add in the symbol's absolute address */ 321 value += (Elf_Word)(defobj->relocbase + def->st_value); 322 } 323 324 if (RELOC_PC_RELATIVE(type)) { 325 value -= (Elf_Word)where; 326 } 327 328 if (RELOC_BASE_RELATIVE(type)) { 329 /* 330 * Note that even though sparcs use `Elf_rela' 331 * exclusively we still need the implicit memory addend 332 * in relocations referring to GOT entries. 333 * Undoubtedly, someone f*cked this up in the distant 334 * past, and now we're stuck with it in the name of 335 * compatibility for all eternity.. 336 * 337 * In any case, the implicit and explicit should be 338 * mutually exclusive. We provide a check for that 339 * here. 340 */ 341#define DIAGNOSTIC 342#ifdef DIAGNOSTIC 343 if (value != 0 && *where != 0) { 344 xprintf("BASE_REL(%s): where=%p, *where 0x%x, " 345 "addend=0x%x, base %p\n", 346 obj->path, where, *where, 347 rela->r_addend, obj->relocbase); 348 } 349#endif 350 value += (Elf_Word)(obj->relocbase + *where); 351 } 352 353 mask = RELOC_VALUE_BITMASK(type); 354 value >>= RELOC_VALUE_RIGHTSHIFT(type); 355 value &= mask; 356 357 if (RELOC_UNALIGNED(type)) { 358 /* Handle unaligned relocations. */ 359 Elf_Addr tmp = 0; 360 char *ptr = (char *)where; 361 int i, size = RELOC_TARGET_SIZE(type)/8; 362 363 /* Read it in one byte at a time. */ 364 for (i=0; i<size; i++) 365 tmp = (tmp << 8) | ptr[i]; 366 367 tmp &= ~mask; 368 tmp |= value; 369 370 /* Write it back out. */ 371 for (i=0; i<size; i++) 372 ptr[i] = ((tmp >> (8*i)) & 0xff); 373#ifdef RTLD_DEBUG_RELOC 374 value = (Elf_Word)tmp; 375#endif 376 377 } else { 378 *where &= ~mask; 379 *where |= value; 380#ifdef RTLD_DEBUG_RELOC 381 value = (Elf_Word)*where; 382#endif 383 } 384#ifdef RTLD_DEBUG_RELOC 385 if (RELOC_RESOLVE_SYMBOL(type)) { 386 rdbg(("%s %s in %s --> %p in %s", reloc_names[type], 387 obj->strtab + obj->symtab[symnum].st_name, 388 obj->path, (void *)value, defobj->path)); 389 } else { 390 rdbg(("%s in %s --> %p", reloc_names[type], 391 obj->path, (void *)value)); 392 } 393#endif 394 } 395 return (0); 396} 397 398int 399_rtld_relocate_plt_lazy(const Obj_Entry *obj) 400{ 401 return (0); 402} 403 404caddr_t 405_rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 406{ 407 const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff); 408 Elf_Addr value; 409 int err; 410 411 value = 0; /* XXX gcc */ 412 413 _rtld_shared_enter(); 414 err = _rtld_relocate_plt_object(obj, rela, &value); 415 if (err) 416 _rtld_die(); 417 _rtld_shared_exit(); 418 419 return (caddr_t)value; 420} 421 422int 423_rtld_relocate_plt_objects(const Obj_Entry *obj) 424{ 425 const Elf_Rela *rela = obj->pltrela; 426 427 for (; rela < obj->pltrelalim; rela++) 428 if (_rtld_relocate_plt_object(obj, rela, NULL) < 0) 429 return -1; 430 431 return 0; 432} 433 434static inline int 435_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp) 436{ 437 const Elf_Sym *def; 438 const Obj_Entry *defobj; 439 Elf_Word *where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 440 Elf_Addr value; 441 unsigned long info = rela->r_info; 442 443 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT)); 444 445 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 446 if (__predict_false(def == NULL)) 447 return -1; 448 if (__predict_false(def == &_rtld_sym_zero)) 449 return 0; 450 451 value = (Elf_Addr)(defobj->relocbase + def->st_value); 452 rdbg(("bind now/fixup in %s --> new=%p", 453 defobj->strtab + def->st_name, (void *)value)); 454 455 /* 456 * At the PLT entry pointed at by `where', we now construct 457 * a direct transfer to the now fully resolved function 458 * address. The resulting code in the jump slot is: 459 * 460 * sethi %hi(roffset), %g1 461 * sethi %hi(addr), %g1 462 * jmp %g1+%lo(addr) 463 * 464 * We write the third instruction first, since that leaves the 465 * previous `b,a' at the second word in place. Hence the whole 466 * PLT slot can be atomically change to the new sequence by 467 * writing the `sethi' instruction at word 2. 468 */ 469#define SETHI 0x03000000 470#define JMP 0x81c06000 471#define NOP 0x01000000 472 where[2] = JMP | (value & 0x000003ff); 473 where[1] = SETHI | ((value >> 10) & 0x003fffff); 474 __asm volatile("iflush %0+8" : : "r" (where)); 475 __asm volatile("iflush %0+4" : : "r" (where)); 476 477 if (tp) 478 *tp = value; 479 480 return 0; 481} 482