1 /* $NetBSD: ppc_reloc.c,v 1.57 2018/04/03 21:10:27 joerg Exp $ */ 2 3 /*- 4 * Copyright (C) 1998 Tsubai Masanari 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 28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #include <sys/cdefs.h> 32 #ifndef lint 33 __RCSID("$NetBSD: ppc_reloc.c,v 1.57 2018/04/03 21:10:27 joerg Exp $"); 34 #endif /* not lint */ 35 36 #include <stdarg.h> 37 #include <stdio.h> 38 #include <stdlib.h> 39 #include <string.h> 40 #include <sys/types.h> 41 #include <machine/cpu.h> 42 43 #include "debug.h" 44 #include "rtld.h" 45 46 void _rtld_powerpc_pltcall(Elf_Word); 47 void _rtld_powerpc_pltresolve(Elf_Word, Elf_Word); 48 49 #define __u64(x) ((uint64_t)(x)) 50 #define __u32(x) ((uint32_t)(x)) 51 #define __ha48 __u64(0xffffffff8000) 52 #define __ha32 __u64(0xffff8000) 53 #define __ha16 __u32(0x8000) 54 #define __ha(x,n) ((((x) >> (n)) + (((x) & __ha##n) == __ha##n)) & 0xffff) 55 #define __hi(x,n) (((x) >> (n)) & 0xffff) 56 #ifdef __LP64 57 #define highesta(x) __ha(__u64(x), 48) 58 #define highest(x) __hi(__u64(x), 48) 59 #define higher(x) __ha(__u64(x), 32) 60 #define higher(x) __hi(__u64(x), 32) 61 #endif 62 #define ha(x) __ha(__u32(x), 16) 63 #define hi(x) __hi(__u32(x), 16) 64 #define lo(x) (__u32(x) & 0xffff) 65 66 #ifdef _LP64 67 /* function descriptor for _rtld_bind_start */ 68 extern const uint64_t _rtld_bind_start[3]; 69 #else 70 void _rtld_bind_bssplt_start(void); 71 void _rtld_bind_secureplt_start(void); 72 #endif 73 Elf_Addr _rtld_bind(const Obj_Entry *, Elf_Word); 74 void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr); 75 static int _rtld_relocate_plt_object(const Obj_Entry *, 76 const Elf_Rela *, int, Elf_Addr *); 77 78 /* 79 * The PPC32 PLT format consists of three sections: 80 * (1) The "pltcall" and "pltresolve" glue code. This is always 18 words. 81 * (2) The code part of the PLT entries. There are 2 words per entry for 82 * up to 8192 entries, then 4 words per entry for any additional entries. 83 * (3) The data part of the PLT entries, comprising a jump table. 84 * This section is half the size of the second section (ie. 1 or 2 words 85 * per entry). 86 */ 87 88 void 89 _rtld_setup_pltgot(const Obj_Entry *obj) 90 { 91 #ifdef _LP64 92 /* 93 * For powerpc64, just copy the function descriptor to pltgot[0]. 94 */ 95 if (obj->pltgot != NULL) { 96 obj->pltgot[0] = (Elf_Addr) _rtld_bind_start[0]; 97 obj->pltgot[1] = (Elf_Addr) _rtld_bind_start[1]; 98 obj->pltgot[2] = (Elf_Addr) obj; 99 } 100 #else 101 /* 102 * Secure-PLT is much more sane. 103 */ 104 if (obj->gotptr != NULL) { 105 obj->gotptr[1] = (Elf_Addr) _rtld_bind_secureplt_start; 106 obj->gotptr[2] = (Elf_Addr) obj; 107 dbg(("obj %s secure-plt gotptr=%p start=%p obj=%p", 108 obj->path, obj->gotptr, 109 (void *) obj->gotptr[1], (void *) obj->gotptr[2])); 110 } else { 111 /* 112 * Setup the plt glue routines (for bss-plt). 113 */ 114 #define BSSPLTCALL_SIZE 20 115 #define BSSPLTRESOLVE_SIZE 24 116 117 Elf_Word *pltcall, *pltresolve; 118 Elf_Word *jmptab; 119 int N = obj->pltrelalim - obj->pltrela; 120 121 /* Entries beyond 8192 take twice as much space. */ 122 if (N > 8192) 123 N += N-8192; 124 125 dbg(("obj %s bss-plt pltgot=%p jmptab=%u start=%p obj=%p", 126 obj->path, obj->pltgot, 18 + N * 2, 127 _rtld_bind_bssplt_start, obj)); 128 129 pltcall = obj->pltgot; 130 jmptab = pltcall + 18 + N * 2; 131 132 memcpy(pltcall, _rtld_powerpc_pltcall, BSSPLTCALL_SIZE); 133 pltcall[1] |= ha(jmptab); 134 pltcall[2] |= lo(jmptab); 135 136 pltresolve = obj->pltgot + 8; 137 138 memcpy(pltresolve, _rtld_powerpc_pltresolve, BSSPLTRESOLVE_SIZE); 139 pltresolve[0] |= ha(_rtld_bind_bssplt_start); 140 pltresolve[1] |= lo(_rtld_bind_bssplt_start); 141 pltresolve[3] |= ha(obj); 142 pltresolve[4] |= lo(obj); 143 144 /* 145 * Invalidate the icache for only the code part of the PLT 146 * (and not the jump table at the end). 147 */ 148 __syncicache(pltcall, (char *)jmptab - (char *)pltcall); 149 } 150 #endif 151 } 152 153 void 154 _rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase) 155 { 156 const Elf_Rela *rela = 0, *relalim; 157 Elf_Addr relasz = 0; 158 Elf_Addr *where; 159 160 for (; dynp->d_tag != DT_NULL; dynp++) { 161 switch (dynp->d_tag) { 162 case DT_RELA: 163 rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr); 164 break; 165 case DT_RELASZ: 166 relasz = dynp->d_un.d_val; 167 break; 168 } 169 } 170 relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz); 171 for (; rela < relalim; rela++) { 172 where = (Elf_Addr *)(relocbase + rela->r_offset); 173 *where = (Elf_Addr)(relocbase + rela->r_addend); 174 } 175 } 176 177 int 178 _rtld_relocate_nonplt_objects(Obj_Entry *obj) 179 { 180 const Elf_Rela *rela; 181 const Elf_Sym *def = NULL; 182 const Obj_Entry *defobj = NULL; 183 unsigned long last_symnum = ULONG_MAX; 184 185 for (rela = obj->rela; rela < obj->relalim; rela++) { 186 Elf_Addr *where; 187 Elf_Addr tmp; 188 unsigned long symnum; 189 190 where = (Elf_Addr *)(obj->relocbase + rela->r_offset); 191 192 switch (ELF_R_TYPE(rela->r_info)) { 193 #ifdef _LP64 194 case R_TYPE(ADDR64): /* <address> S + A */ 195 #else 196 case R_TYPE(ADDR32): /* <address> S + A */ 197 #endif 198 case R_TYPE(GLOB_DAT): /* <address> S + A */ 199 case R_TYPE(DTPMOD): 200 case R_TYPE(DTPREL): 201 case R_TYPE(TPREL): 202 symnum = ELF_R_SYM(rela->r_info); 203 if (last_symnum != symnum) { 204 last_symnum = symnum; 205 def = _rtld_find_symdef(symnum, obj, &defobj, 206 false); 207 if (def == NULL) 208 return -1; 209 } 210 break; 211 default: 212 break; 213 } 214 215 switch (ELF_R_TYPE(rela->r_info)) { 216 #if 1 /* XXX Should not be necessary. */ 217 case R_TYPE(JMP_SLOT): 218 #endif 219 case R_TYPE(NONE): 220 break; 221 222 #ifdef _LP64 223 case R_TYPE(ADDR64): /* <address> S + A */ 224 #else 225 case R_TYPE(ADDR32): /* <address> S + A */ 226 #endif 227 case R_TYPE(GLOB_DAT): /* <address> S + A */ 228 tmp = (Elf_Addr)(defobj->relocbase + def->st_value + 229 rela->r_addend); 230 if (*where != tmp) 231 *where = tmp; 232 rdbg(("32/GLOB_DAT %s in %s --> %p in %s", 233 obj->strtab + obj->symtab[symnum].st_name, 234 obj->path, (void *)*where, defobj->path)); 235 break; 236 237 case R_TYPE(RELATIVE): /* <address> B + A */ 238 *where = (Elf_Addr)(obj->relocbase + rela->r_addend); 239 rdbg(("RELATIVE in %s --> %p", obj->path, 240 (void *)*where)); 241 break; 242 243 case R_TYPE(COPY): 244 /* 245 * These are deferred until all other relocations have 246 * been done. All we do here is make sure that the 247 * COPY relocation is not in a shared library. They 248 * are allowed only in executable files. 249 */ 250 if (obj->isdynamic) { 251 _rtld_error( 252 "%s: Unexpected R_COPY relocation in shared library", 253 obj->path); 254 return -1; 255 } 256 rdbg(("COPY (avoid in main)")); 257 break; 258 259 case R_TYPE(DTPMOD): 260 *where = (Elf_Addr)defobj->tlsindex; 261 rdbg(("DTPMOD32 %s in %s --> %p in %s", 262 obj->strtab + obj->symtab[symnum].st_name, 263 obj->path, (void *)*where, defobj->path)); 264 break; 265 266 case R_TYPE(DTPREL): 267 if (!defobj->tls_done && _rtld_tls_offset_allocate(obj)) 268 return -1; 269 270 *where = (Elf_Addr)(def->st_value + rela->r_addend 271 - TLS_DTV_OFFSET); 272 rdbg(("DTPREL32 %s in %s --> %p in %s", 273 obj->strtab + obj->symtab[symnum].st_name, 274 obj->path, (void *)*where, defobj->path)); 275 break; 276 277 case R_TYPE(TPREL): 278 if (!defobj->tls_done && _rtld_tls_offset_allocate(obj)) 279 return -1; 280 281 *where = (Elf_Addr)(def->st_value + rela->r_addend 282 + defobj->tlsoffset - TLS_TP_OFFSET); 283 rdbg(("TPREL32 %s in %s --> %p in %s", 284 obj->strtab + obj->symtab[symnum].st_name, 285 obj->path, (void *)*where, defobj->path)); 286 break; 287 288 case R_TYPE(IRELATIVE): 289 /* IFUNC relocations are handled in _rtld_call_ifunc */ 290 if (obj->ifunc_remaining_nonplt == 0) { 291 obj->ifunc_remaining_nonplt = 292 obj->relalim - rela; 293 } 294 break; 295 296 default: 297 rdbg(("sym = %lu, type = %lu, offset = %p, " 298 "addend = %p, contents = %p, symbol = %s", 299 (u_long)ELF_R_SYM(rela->r_info), 300 (u_long)ELF_R_TYPE(rela->r_info), 301 (void *)rela->r_offset, (void *)rela->r_addend, 302 (void *)*where, 303 obj->strtab + obj->symtab[symnum].st_name)); 304 _rtld_error("%s: Unsupported relocation type %ld " 305 "in non-PLT relocations", 306 obj->path, (u_long) ELF_R_TYPE(rela->r_info)); 307 return -1; 308 } 309 } 310 return 0; 311 } 312 313 int 314 _rtld_relocate_plt_lazy(Obj_Entry *obj) 315 { 316 #ifdef _LP64 317 /* 318 * For PowerPC64, the plt stubs handle an empty function descriptor 319 * so there's nothing to do. 320 */ 321 /* XXX ifunc support */ 322 #else 323 Elf_Addr * const pltresolve = obj->pltgot + 8; 324 const Elf_Rela *rela; 325 326 for (rela = obj->pltrelalim; rela-- > obj->pltrela;) { 327 size_t reloff = rela - obj->pltrela; 328 Elf_Word *where = (Elf_Word *)(obj->relocbase + rela->r_offset); 329 330 assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JUMP_SLOT) || 331 ELF_R_TYPE(rela->r_info) == R_TYPE(IRELATIVE)); 332 333 if (ELF_R_TYPE(rela->r_info) == R_TYPE(IRELATIVE)) { 334 /* No ifunc support for old-style insecure PLT. */ 335 assert(obj->gotptr != NULL); 336 obj->ifunc_remaining = obj->pltrelalim - rela; 337 } 338 339 if (obj->gotptr != NULL) { 340 /* 341 * For now, simply treat then as relative. 342 */ 343 *where += (Elf_Addr)obj->relocbase; 344 } else { 345 int distance; 346 347 if (reloff < 32768) { 348 /* li r11,reloff */ 349 *where++ = 0x39600000 | reloff; 350 } else { 351 /* lis r11,ha(reloff) */ 352 /* addi r11,lo(reloff) */ 353 *where++ = 0x3d600000 | ha(reloff); 354 *where++ = 0x396b0000 | lo(reloff); 355 } 356 /* b pltresolve */ 357 distance = (Elf_Addr)pltresolve - (Elf_Addr)where; 358 *where++ = 0x48000000 | (distance & 0x03fffffc); 359 360 /* 361 * Icache invalidation is not done for each entry here 362 * because we sync the entire code part of the PLT once 363 * in _rtld_setup_pltgot() after all the entries have been 364 * initialized. 365 */ 366 /* __syncicache(where - 3, 12); */ 367 } 368 } 369 #endif /* !_LP64 */ 370 371 return 0; 372 } 373 374 static int 375 _rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, int reloff, Elf_Addr *tp) 376 { 377 Elf_Word *where = (Elf_Word *)(obj->relocbase + rela->r_offset); 378 Elf_Addr value; 379 const Elf_Sym *def; 380 const Obj_Entry *defobj; 381 unsigned long info = rela->r_info; 382 383 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT)); 384 385 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL); 386 if (__predict_false(def == NULL)) 387 return -1; 388 if (__predict_false(def == &_rtld_sym_zero)) 389 return 0; 390 391 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) { 392 if (tp == NULL) 393 return 0; 394 value = _rtld_resolve_ifunc(defobj, def); 395 } else { 396 value = (Elf_Addr)(defobj->relocbase + def->st_value); 397 } 398 rdbg(("bind now/fixup in %s --> new=%p", 399 defobj->strtab + def->st_name, (void *)value)); 400 401 #ifdef _LP64 402 /* 403 * For PowerPC64 we simply replace the function descriptor in the 404 * PLTGOT with the one from source object. 405 */ 406 assert(where >= (Elf_Word *)obj->pltgot); 407 assert(where < (Elf_Word *)obj->pltgot + (obj->pltrelalim - obj->pltrela)); 408 const Elf_Addr * const fdesc = (Elf_Addr *) value; 409 where[0] = fdesc[0]; 410 where[1] = fdesc[1]; 411 where[2] = fdesc[2]; 412 #else 413 ptrdiff_t distance = value - (Elf_Addr)where; 414 if (obj->gotptr != NULL) { 415 /* 416 * For Secure-PLT we simply replace the entry in GOT with the 417 * address of the routine. 418 */ 419 assert(where >= (Elf_Word *)obj->pltgot); 420 assert(where < (Elf_Word *)obj->pltgot + (obj->pltrelalim - obj->pltrela)); 421 *where = value; 422 } else if (labs(distance) < 32*1024*1024) { /* inside 32MB? */ 423 /* b value # branch directly */ 424 *where = 0x48000000 | (distance & 0x03fffffc); 425 __syncicache(where, 4); 426 } else { 427 Elf_Addr *pltcall, *jmptab; 428 int N = obj->pltrelalim - obj->pltrela; 429 430 /* Entries beyond 8192 take twice as much space. */ 431 if (N > 8192) 432 N += N-8192; 433 434 pltcall = obj->pltgot; 435 jmptab = pltcall + 18 + N * 2; 436 437 jmptab[reloff] = value; 438 439 if (reloff < 32768) { 440 /* li r11,reloff */ 441 *where++ = 0x39600000 | reloff; 442 } else { 443 #ifdef notyet 444 /* lis r11,ha(value) */ 445 /* addi r11,lo(value) */ 446 /* mtctr r11 */ 447 /* bctr */ 448 *where++ = 0x3d600000 | ha(value); 449 *where++ = 0x396b0000 | lo(value); 450 *where++ = 0x7d6903a6; 451 *where++ = 0x4e800420; 452 #else 453 /* lis r11,ha(reloff) */ 454 /* addi r11,lo(reloff) */ 455 *where++ = 0x3d600000 | ha(reloff); 456 *where++ = 0x396b0000 | lo(reloff); 457 #endif 458 } 459 /* b pltcall */ 460 distance = (Elf_Addr)pltcall - (Elf_Addr)where; 461 *where++ = 0x48000000 | (distance & 0x03fffffc); 462 __syncicache(where - 3, 12); 463 } 464 #endif /* _LP64 */ 465 466 if (tp) 467 *tp = value; 468 return 0; 469 } 470 471 Elf_Addr 472 _rtld_bind(const Obj_Entry *obj, Elf_Word reloff) 473 { 474 const Elf_Rela *rela = obj->pltrela + reloff; 475 Elf_Addr new_value; 476 int err; 477 478 new_value = 0; /* XXX gcc */ 479 480 _rtld_shared_enter(); 481 err = _rtld_relocate_plt_object(obj, rela, reloff, &new_value); 482 if (err) 483 _rtld_die(); 484 _rtld_shared_exit(); 485 486 #ifdef _LP64 487 return obj->glink; 488 #else 489 return new_value; 490 #endif 491 } 492 493 int 494 _rtld_relocate_plt_objects(const Obj_Entry *obj) 495 { 496 const Elf_Rela *rela; 497 int reloff; 498 499 for (rela = obj->pltrela, reloff = 0; rela < obj->pltrelalim; rela++, reloff++) { 500 if (_rtld_relocate_plt_object(obj, rela, reloff, NULL) < 0) 501 return -1; 502 } 503 return 0; 504 } 505