1 /* $OpenBSD: rtld_machine.c,v 1.68 2019/12/07 22:57:48 guenther Exp $ */ 2 3 /* 4 * Copyright (c) 1999 Dale Rahn 5 * Copyright (c) 2001 Niklas Hallqvist 6 * Copyright (c) 2001 Artur Grabowski 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 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 18 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY 21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 /*- 30 * Copyright (c) 2000 Eduardo Horvath. 31 * Copyright (c) 1999 The NetBSD Foundation, Inc. 32 * All rights reserved. 33 * 34 * This code is derived from software contributed to The NetBSD Foundation 35 * by Paul Kranenburg. 36 * 37 * Redistribution and use in source and binary forms, with or without 38 * modification, are permitted provided that the following conditions 39 * are met: 40 * 1. Redistributions of source code must retain the above copyright 41 * notice, this list of conditions and the following disclaimer. 42 * 2. Redistributions in binary form must reproduce the above copyright 43 * notice, this list of conditions and the following disclaimer in the 44 * documentation and/or other materials provided with the distribution. 45 * 3. All advertising materials mentioning features or use of this software 46 * must display the following acknowledgement: 47 * This product includes software developed by the NetBSD 48 * Foundation, Inc. and its contributors. 49 * 4. Neither the name of The NetBSD Foundation nor the names of its 50 * contributors may be used to endorse or promote products derived 51 * from this software without specific prior written permission. 52 * 53 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 54 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 55 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 56 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 57 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 58 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 59 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 60 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 61 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 62 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 63 * POSSIBILITY OF SUCH DAMAGE. 64 */ 65 66 #define _DYN_LOADER 67 68 #include <sys/types.h> 69 #include <sys/mman.h> 70 #include <sys/syscall.h> 71 #include <sys/unistd.h> 72 #include <machine/trap.h> 73 74 #include <nlist.h> 75 #include <link.h> 76 77 #include "syscall.h" 78 #include "archdep.h" 79 #include "resolve.h" 80 81 int64_t pcookie __attribute__((section(".openbsd.randomdata"))) __dso_hidden; 82 83 /* 84 * The following table holds for each relocation type: 85 * - the width in bits of the memory location the relocation 86 * applies to (not currently used) 87 * - the number of bits the relocation value must be shifted to the 88 * right (i.e. discard least significant bits) to fit into 89 * the appropriate field in the instruction word. 90 * - flags indicating whether 91 * * the relocation involves a symbol 92 * * the relocation is relative to the current position 93 * * the relocation is for a GOT entry 94 * * the relocation is relative to the load address 95 * 96 */ 97 #define _RF_S 0x80000000 /* Resolve symbol */ 98 #define _RF_A 0x40000000 /* Use addend */ 99 #define _RF_P 0x20000000 /* Location relative */ 100 #define _RF_G 0x10000000 /* GOT offset */ 101 #define _RF_B 0x08000000 /* Load address relative */ 102 #define _RF_U 0x04000000 /* Unaligned */ 103 #define _RF_SZ(s) (((s) & 0xff) << 8) /* memory target size */ 104 #define _RF_RS(s) ((s) & 0xff) /* right shift */ 105 static const int reloc_target_flags[] = { 106 0, /* NONE */ 107 _RF_S|_RF_A| _RF_SZ(8) | _RF_RS(0), /* RELOC_8 */ 108 _RF_S|_RF_A| _RF_SZ(16) | _RF_RS(0), /* RELOC_16 */ 109 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* RELOC_32 */ 110 _RF_S|_RF_A|_RF_P| _RF_SZ(8) | _RF_RS(0), /* DISP_8 */ 111 _RF_S|_RF_A|_RF_P| _RF_SZ(16) | _RF_RS(0), /* DISP_16 */ 112 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* DISP_32 */ 113 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WDISP_30 */ 114 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WDISP_22 */ 115 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(10), /* HI22 */ 116 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 22 */ 117 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 13 */ 118 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* LO10 */ 119 _RF_G| _RF_SZ(32) | _RF_RS(0), /* GOT10 */ 120 _RF_G| _RF_SZ(32) | _RF_RS(0), /* GOT13 */ 121 _RF_G| _RF_SZ(32) | _RF_RS(10), /* GOT22 */ 122 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* PC10 */ 123 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(10), /* PC22 */ 124 _RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WPLT30 */ 125 _RF_S| _RF_SZ(32) | _RF_RS(0), /* COPY */ 126 _RF_S|_RF_A| _RF_SZ(64) | _RF_RS(0), /* GLOB_DAT */ 127 _RF_S| _RF_SZ(32) | _RF_RS(0), /* JMP_SLOT */ 128 _RF_A| _RF_B| _RF_SZ(64) | _RF_RS(0), /* RELATIVE */ 129 _RF_S|_RF_A| _RF_U| _RF_SZ(32) | _RF_RS(0), /* UA_32 */ 130 131 _RF_A| _RF_SZ(32) | _RF_RS(0), /* PLT32 */ 132 _RF_A| _RF_SZ(32) | _RF_RS(10), /* HIPLT22 */ 133 _RF_A| _RF_SZ(32) | _RF_RS(0), /* LOPLT10 */ 134 _RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* PCPLT32 */ 135 _RF_A|_RF_P| _RF_SZ(32) | _RF_RS(10), /* PCPLT22 */ 136 _RF_A|_RF_P| _RF_SZ(32) | _RF_RS(0), /* PCPLT10 */ 137 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 10 */ 138 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 11 */ 139 _RF_S|_RF_A| _RF_SZ(64) | _RF_RS(0), /* 64 */ 140 _RF_S|_RF_A|/*extra*/ _RF_SZ(32) | _RF_RS(0), /* OLO10 */ 141 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(42), /* HH22 */ 142 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(32), /* HM10 */ 143 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(10), /* LM22 */ 144 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(42), /* PC_HH22 */ 145 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(32), /* PC_HM10 */ 146 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(10), /* PC_LM22 */ 147 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WDISP16 */ 148 _RF_S|_RF_A|_RF_P| _RF_SZ(32) | _RF_RS(2), /* WDISP19 */ 149 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* GLOB_JMP */ 150 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 7 */ 151 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 5 */ 152 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* 6 */ 153 _RF_S|_RF_A|_RF_P| _RF_SZ(64) | _RF_RS(0), /* DISP64 */ 154 _RF_A| _RF_SZ(64) | _RF_RS(0), /* PLT64 */ 155 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(10), /* HIX22 */ 156 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* LOX10 */ 157 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(22), /* H44 */ 158 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(12), /* M44 */ 159 _RF_S|_RF_A| _RF_SZ(32) | _RF_RS(0), /* L44 */ 160 _RF_S|_RF_A| _RF_SZ(64) | _RF_RS(0), /* REGISTER */ 161 _RF_S|_RF_A| _RF_U| _RF_SZ(64) | _RF_RS(0), /* UA64 */ 162 _RF_S|_RF_A| _RF_U| _RF_SZ(16) | _RF_RS(0), /* UA16 */ 163 }; 164 165 #define RELOC_RESOLVE_SYMBOL(t) ((reloc_target_flags[t] & _RF_S) != 0) 166 #define RELOC_PC_RELATIVE(t) ((reloc_target_flags[t] & _RF_P) != 0) 167 #define RELOC_BASE_RELATIVE(t) ((reloc_target_flags[t] & _RF_B) != 0) 168 #define RELOC_UNALIGNED(t) ((reloc_target_flags[t] & _RF_U) != 0) 169 #define RELOC_USE_ADDEND(t) ((reloc_target_flags[t] & _RF_A) != 0) 170 #define RELOC_TARGET_SIZE(t) ((reloc_target_flags[t] >> 8) & 0xff) 171 #define RELOC_VALUE_RIGHTSHIFT(t) (reloc_target_flags[t] & 0xff) 172 173 static const long reloc_target_bitmask[] = { 174 #define _BM(x) (~(-(1ULL << (x)))) 175 0, /* NONE */ 176 _BM(8), _BM(16), _BM(32), /* RELOC_8, _16, _32 */ 177 _BM(8), _BM(16), _BM(32), /* DISP8, DISP16, DISP32 */ 178 _BM(30), _BM(22), /* WDISP30, WDISP22 */ 179 _BM(22), _BM(22), /* HI22, _22 */ 180 _BM(13), _BM(10), /* RELOC_13, _LO10 */ 181 _BM(10), _BM(13), _BM(22), /* GOT10, GOT13, GOT22 */ 182 _BM(10), _BM(22), /* _PC10, _PC22 */ 183 _BM(30), 0, /* _WPLT30, _COPY */ 184 -1, _BM(32), -1, /* _GLOB_DAT, JMP_SLOT, _RELATIVE */ 185 _BM(32), _BM(32), /* _UA32, PLT32 */ 186 _BM(22), _BM(10), /* _HIPLT22, LOPLT10 */ 187 _BM(32), _BM(22), _BM(10), /* _PCPLT32, _PCPLT22, _PCPLT10 */ 188 _BM(10), _BM(11), -1, /* _10, _11, _64 */ 189 _BM(10), _BM(22), /* _OLO10, _HH22 */ 190 _BM(10), _BM(22), /* _HM10, _LM22 */ 191 _BM(22), _BM(10), _BM(22), /* _PC_HH22, _PC_HM10, _PC_LM22 */ 192 _BM(16), _BM(19), /* _WDISP16, _WDISP19 */ 193 -1, /* GLOB_JMP */ 194 _BM(7), _BM(5), _BM(6) /* _7, _5, _6 */ 195 -1, -1, /* DISP64, PLT64 */ 196 _BM(22), _BM(13), /* HIX22, LOX10 */ 197 _BM(22), _BM(10), _BM(13), /* H44, M44, L44 */ 198 -1, -1, _BM(16), /* REGISTER, UA64, UA16 */ 199 #undef _BM 200 }; 201 #define RELOC_VALUE_BITMASK(t) (reloc_target_bitmask[t]) 202 203 int _dl_reloc_plt(Elf_Word *where1, Elf_Word *where2, Elf_Word *pltaddr, 204 Elf_Addr value); 205 void _dl_install_plt(Elf_Word *pltgot, Elf_Addr proc); 206 207 int 208 _dl_md_reloc(elf_object_t *object, int rel, int relasz) 209 { 210 long i; 211 long numrela; 212 long relrel; 213 int fails = 0; 214 Elf_Addr loff; 215 Elf_Addr prev_value = 0; 216 const Elf_Sym *prev_sym = NULL; 217 Elf_RelA *relas; 218 219 loff = object->obj_base; 220 numrela = object->Dyn.info[relasz] / sizeof(Elf_RelA); 221 relrel = rel == DT_RELA ? object->relacount : 0; 222 relas = (Elf_RelA *)(object->Dyn.info[rel]); 223 224 if (relas == NULL) 225 return 0; 226 227 if (relrel > numrela) 228 _dl_die("relacount > numrel: %ld > %ld", relrel, numrela); 229 230 /* tight loop for leading RELATIVE relocs */ 231 for (i = 0; i < relrel; i++, relas++) { 232 Elf_Addr *where; 233 234 where = (Elf_Addr *)(relas->r_offset + loff); 235 *where = relas->r_addend + loff; 236 } 237 for (; i < numrela; i++, relas++) { 238 Elf_Addr *where, value, mask; 239 Elf_Word type; 240 const Elf_Sym *sym; 241 const char *symn; 242 243 type = ELF_R_TYPE(relas->r_info); 244 245 if (type == R_TYPE(NONE) || type == R_TYPE(JMP_SLOT)) 246 continue; 247 248 where = (Elf_Addr *)(relas->r_offset + loff); 249 250 if (RELOC_USE_ADDEND(type)) 251 value = relas->r_addend; 252 else 253 value = 0; 254 255 sym = NULL; 256 symn = NULL; 257 if (RELOC_RESOLVE_SYMBOL(type)) { 258 sym = object->dyn.symtab; 259 sym += ELF_R_SYM(relas->r_info); 260 symn = object->dyn.strtab + sym->st_name; 261 262 if (sym->st_shndx != SHN_UNDEF && 263 ELF_ST_BIND(sym->st_info) == STB_LOCAL) { 264 value += loff; 265 } else if (sym == prev_sym) { 266 value += prev_value; 267 } else { 268 struct sym_res sr; 269 270 sr = _dl_find_symbol(symn, 271 SYM_SEARCH_ALL|SYM_WARNNOTFOUND|SYM_NOTPLT, 272 sym, object); 273 if (sr.sym == NULL) { 274 resolve_failed: 275 if (ELF_ST_BIND(sym->st_info) != 276 STB_WEAK) 277 fails++; 278 continue; 279 } 280 prev_sym = sym; 281 prev_value = (Elf_Addr)(sr.obj->obj_base + 282 sr.sym->st_value); 283 value += prev_value; 284 } 285 } 286 287 if (type == R_TYPE(COPY)) { 288 void *dstaddr = where; 289 const void *srcaddr; 290 const Elf_Sym *dstsym = sym; 291 struct sym_res sr; 292 293 sr = _dl_find_symbol(symn, 294 SYM_SEARCH_OTHER|SYM_WARNNOTFOUND|SYM_NOTPLT, 295 dstsym, object); 296 if (sr.sym == NULL) 297 goto resolve_failed; 298 299 srcaddr = (void *)(sr.obj->obj_base + sr.sym->st_value); 300 _dl_bcopy(srcaddr, dstaddr, dstsym->st_size); 301 continue; 302 } 303 304 if (RELOC_PC_RELATIVE(type)) 305 value -= (Elf_Addr)where; 306 if (RELOC_BASE_RELATIVE(type)) 307 value += loff; 308 309 mask = RELOC_VALUE_BITMASK(type); 310 value >>= RELOC_VALUE_RIGHTSHIFT(type); 311 value &= mask; 312 313 if (RELOC_UNALIGNED(type)) { 314 /* Handle unaligned relocations. */ 315 Elf_Addr tmp = 0; 316 char *ptr = (char *)where; 317 int i, size = RELOC_TARGET_SIZE(type)/8; 318 319 /* Read it in one byte at a time. */ 320 for (i=0; i<size; i++) 321 tmp = (tmp << 8) | ptr[i]; 322 323 tmp &= ~mask; 324 tmp |= value; 325 326 /* Write it back out. */ 327 for (i=0; i<size; i++) 328 ptr[i] = ((tmp >> (8*i)) & 0xff); 329 } else if (RELOC_TARGET_SIZE(type) > 32) { 330 *where &= ~mask; 331 *where |= value; 332 } else { 333 Elf32_Addr *where32 = (Elf32_Addr *)where; 334 335 *where32 &= ~mask; 336 *where32 |= value; 337 } 338 } 339 340 return fails; 341 } 342 343 /* 344 * Instruction templates: 345 */ 346 347 #define BAA 0x30680000 /* ba,a %xcc, 0 */ 348 #define SETHI 0x03000000 /* sethi %hi(0), %g1 */ 349 #define JMP 0x81c06000 /* jmpl %g1+%lo(0), %g0 <-- simm13 */ 350 #define NOP 0x01000000 /* sethi %hi(0), %g0 */ 351 #define OR 0x82106000 /* or %g1, 0, %g1 */ 352 #define ORG5 0x8a116000 /* or %g5, 0, %g5 */ 353 #define XOR 0x82186000 /* xor %g1, 0, %g1 */ 354 #define MOV71 0x8210000f /* or %o7, 0, %g1 */ 355 #define MOV17 0x9e100001 /* or %g1, 0, %o7 */ 356 #define CALL 0x40000000 /* call 0 <-- disp30 */ 357 #define SLLX 0x83287000 /* sllx %g1, 0, %g1 */ 358 #define SLLXG5 0x8b297000 /* sllx %g5, 0, %g5 */ 359 #define SRAX 0x83387000 /* srax %g1, 0, %g1 */ 360 #define SETHIG5 0x0b000000 /* sethi %hi(0), %g5 */ 361 #define ORG15 0x82804005 /* or %g1, %g5, %g1 */ 362 363 364 /* %hi(v) with variable shift */ 365 #define HIVAL(v, s) (((v) >> (s)) & 0x003fffff) 366 #define LOVAL(v) ((v) & 0x000003ff) 367 368 int 369 _dl_reloc_plt(Elf_Word *where1, Elf_Word *where2, Elf_Word *pltaddr, 370 Elf_Addr value) 371 { 372 Elf_Addr offset; 373 374 /* 375 * At the PLT entry pointed at by `where', we now construct 376 * a direct transfer to the now fully resolved function 377 * address. 378 * 379 * A PLT entry is supposed to start by looking like this: 380 * 381 * sethi %hi(. - .PLT0), %g1 382 * ba,a,pt %xcc, .PLT1 383 * nop 384 * nop 385 * nop 386 * nop 387 * nop 388 * nop 389 * 390 * When we replace these entries we either (a) only replace 391 * the second word (the ba,a,pt), or (b) replace multiple 392 * words: one or more nops, then finally the ba,a,pt. By 393 * replacing the ba,a,pt last, we guarantee that the PLT can 394 * be used by other threads even while it's being updated. 395 * This is made slightly more complicated by kbind, for which 396 * we need to pass them to the kernel in the order they get 397 * written. To that end, we store the word to overwrite the 398 * ba,a,pt at *where1, and the words to overwrite the nops at 399 * where2[0], where2[1], ... 400 * 401 * We now need to find out how far we need to jump. We 402 * have a choice of several different relocation techniques 403 * which are increasingly expensive. 404 */ 405 406 offset = value - ((Elf_Addr)pltaddr); 407 if ((int64_t)(offset-4) <= (1L<<20) && 408 (int64_t)(offset-4) >= -(1L<<20)) { 409 /* 410 * We're within 1MB -- we can use a direct branch insn. 411 * 412 * We can generate this pattern: 413 * 414 * sethi %hi(. - .PLT0), %g1 415 * ba,a,pt %xcc, addr 416 * nop 417 * nop 418 * nop 419 * nop 420 * nop 421 * nop 422 * 423 */ 424 *where1 = BAA | (((offset-4) >> 2) &0x7ffff); 425 return 0; 426 } else if (value < (1UL<<32)) { 427 /* 428 * We're within 32-bits of address zero. 429 * 430 * The resulting code in the jump slot is: 431 * 432 * sethi %hi(. - .PLT0), %g1 433 * sethi %hi(addr), %g1 434 * jmp %g1+%lo(addr) 435 * nop 436 * nop 437 * nop 438 * nop 439 * nop 440 * 441 */ 442 *where1 = SETHI | HIVAL(value, 10); 443 where2[0] = JMP | LOVAL(value); 444 return 1; 445 } else if (value > -(1UL<<32)) { 446 /* 447 * We're within 32-bits of address -1. 448 * 449 * The resulting code in the jump slot is: 450 * 451 * sethi %hi(. - .PLT0), %g1 452 * sethi %hix(~addr), %g1 453 * xor %g1, %lox(~addr), %g1 454 * jmp %g1 455 * nop 456 * nop 457 * nop 458 * nop 459 * 460 */ 461 *where1 = SETHI | HIVAL(~value, 10); 462 where2[0] = XOR | ((~value) & 0x00001fff); 463 where2[1] = JMP; 464 return 2; 465 } else if ((int64_t)(offset-8) <= (1L<<31) && 466 (int64_t)(offset-8) >= -((1L<<31) - 4)) { 467 /* 468 * We're within 32-bits -- we can use a direct call insn 469 * 470 * The resulting code in the jump slot is: 471 * 472 * sethi %hi(. - .PLT0), %g1 473 * mov %o7, %g1 474 * call (.+offset) 475 * mov %g1, %o7 476 * nop 477 * nop 478 * nop 479 * nop 480 * 481 */ 482 *where1 = MOV71; 483 where2[0] = CALL | (((offset-8) >> 2) & 0x3fffffff); 484 where2[1] = MOV17; 485 return 2; 486 } else if (value < (1L<<42)) { 487 /* 488 * Target 42bits or smaller. 489 * We can generate this pattern: 490 * 491 * The resulting code in the jump slot is: 492 * 493 * sethi %hi(. - .PLT0), %g1 494 * sethi %hi(addr >> 20), %g1 495 * or %g1, %lo(addr >> 10), %g1 496 * sllx %g1, 10, %g1 497 * jmp %g1+%lo(addr) 498 * nop 499 * nop 500 * nop 501 * 502 * this can handle addresses 0 - 0x3fffffffffc 503 */ 504 *where1 = SETHI | HIVAL(value, 20); 505 where2[0] = OR | LOVAL(value >> 10); 506 where2[1] = SLLX | 10; 507 where2[2] = JMP | LOVAL(value); 508 return 3; 509 } else if (value > -(1UL<<41)) { 510 /* 511 * Large target >= 0xfffffe0000000000UL 512 * We can generate this pattern: 513 * 514 * The resulting code in the jump slot is: 515 * 516 * sethi %hi(. - .PLT0), %g1 517 * sethi %hi(addr >> 20), %g1 518 * or %g1, %lo(addr >> 10), %g1 519 * sllx %g1, 32, %g1 520 * srax %g1, 22, %g1 521 * jmp %g1+%lo(addr) 522 * nop 523 * nop 524 * nop 525 * 526 */ 527 *where1 = SETHI | HIVAL(value, 20); 528 where2[0] = OR | LOVAL(value >> 10); 529 where2[1] = SLLX | 32; 530 where2[2] = SRAX | 22; 531 where2[3] = JMP | LOVAL(value); 532 return 4; 533 } else { 534 /* 535 * We need to load all 64-bits 536 * 537 * The resulting code in the jump slot is: 538 * 539 * sethi %hi(. - .PLT0), %g1 540 * sethi %hi(addr >> 42), %g5 541 * sethi %hi(addr >> 10), %g1 542 * or %g1, %lo(addr >> 32), %g5 543 * sllx %g5, 32, %g5 544 * or %g1, %g5, %g1 545 * jmp %g1+%lo(addr) 546 * nop 547 * 548 */ 549 *where1 = SETHIG5 | HIVAL(value, 42); 550 where2[0] = SETHI | HIVAL(value, 10); 551 where2[1] = ORG5 | LOVAL(value >> 32); 552 where2[2] = SLLXG5 | 32; 553 where2[3] = ORG15; 554 where2[4] = JMP | LOVAL(value); 555 return 5; 556 } 557 } 558 559 /* 560 * Resolve a symbol at run-time. 561 */ 562 Elf_Addr 563 _dl_bind(elf_object_t *object, int index) 564 { 565 Elf_RelA *rela; 566 Elf_Word *addr; 567 Elf_Addr newvalue; 568 struct sym_res sr; 569 const Elf_Sym *sym; 570 const char *symn; 571 int64_t cookie = pcookie; 572 struct { 573 struct __kbind param[2]; 574 Elf_Word newval[6]; 575 } buf; 576 struct __kbind *param; 577 size_t psize; 578 int i; 579 580 rela = (Elf_RelA *)(object->Dyn.info[DT_JMPREL]); 581 if (ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT)) { 582 /* 583 * XXXX 584 * 585 * The first four PLT entries are reserved. There 586 * is some disagreement whether they should have 587 * associated relocation entries. Both the SPARC 588 * 32-bit and 64-bit ELF specifications say that 589 * they should have relocation entries, but the 590 * 32-bit SPARC binutils do not generate them, 591 * and now the 64-bit SPARC binutils have stopped 592 * generating them too. 593 * 594 * So, to provide binary compatibility, we will 595 * check the first entry, if it is reserved it 596 * should not be of the type JMP_SLOT. If it 597 * is JMP_SLOT, then the 4 reserved entries were 598 * not generated and our index is 4 entries too far. 599 */ 600 rela += index - 4; 601 } else 602 rela += index; 603 604 sym = object->dyn.symtab; 605 sym += ELF_R_SYM(rela->r_info); 606 symn = object->dyn.strtab + sym->st_name; 607 608 sr = _dl_find_symbol(symn, SYM_SEARCH_ALL|SYM_WARNNOTFOUND|SYM_PLT, 609 sym, object); 610 if (sr.sym == NULL) 611 _dl_die("lazy binding failed!"); 612 613 newvalue = sr.obj->obj_base + sr.sym->st_value; 614 615 if (__predict_false(sr.obj->traced) && _dl_trace_plt(sr.obj, symn)) 616 return newvalue; 617 618 /* 619 * While some relocations just need to write one word and 620 * can do that with kbind() with just one block, many 621 * require two blocks to be written: all but first word, 622 * then the first word. So, if we want to write 5 words 623 * in total, then the layout of the buffer we pass to 624 * kbind() needs to be one of these: 625 * +------------+ 626 * | kbind.addr | 627 * | """ | 628 * | kbind.size | 629 * | """ | +------------+ 630 * | kbind.addr | | kbind.addr | 631 * | """ | | """ | 632 * | kbind.size | | kbind.size | 633 * | """ | | """ | 634 * | word 2 | | word | 635 * | word 3 | +------------+ 636 * | word 4 | 637 * | word 5 | 638 * | word 1 | 639 * +------------+ 640 * 641 * We first handle the special case of relocations with a 642 * non-zero r_addend, which have one block to update whose 643 * address is the relocation address itself. This is only 644 * used for PLT entries after the 2^15th, i.e., truly monstrous 645 * programs, thus the __predict_false(). 646 */ 647 addr = (Elf_Word *)(object->obj_base + rela->r_offset); 648 _dl_memset(&buf, 0, sizeof(buf)); 649 if (__predict_false(rela->r_addend)) { 650 /* 651 * This entry is >32768. The relocation points to a 652 * PC-relative pointer to the _dl_bind_start_0 stub at 653 * the top of the PLT section. Update it to point to 654 * the target function. 655 */ 656 buf.newval[0] = rela->r_addend + newvalue 657 - object->Dyn.info[DT_PLTGOT]; 658 buf.param[1].kb_addr = addr; 659 buf.param[1].kb_size = sizeof(buf.newval[0]); 660 param = &buf.param[1]; 661 psize = sizeof(struct __kbind) + sizeof(buf.newval[0]); 662 } else { 663 Elf_Word first; 664 665 /* 666 * For the other relocations, the word at the relocation 667 * address will be left unchanged. Assume _dl_reloc_plt() 668 * will tell us to update multiple words, so save the first 669 * word to the side. 670 */ 671 i = _dl_reloc_plt(&first, &buf.newval[0], addr, newvalue); 672 673 /* 674 * _dl_reloc_plt() returns the number of words that must be 675 * written after the first word in location, but before it 676 * in time. If it returns zero, then only a single block 677 * with one word is needed, so we just put it in place per 678 * the right-hand diagram and just use param[1] and newval[0] 679 */ 680 if (i == 0) { 681 /* fill in the __kbind structure */ 682 buf.param[1].kb_addr = &addr[1]; 683 buf.param[1].kb_size = sizeof(Elf_Word); 684 buf.newval[0] = first; 685 param = &buf.param[1]; 686 psize = sizeof(struct __kbind) + sizeof(buf.newval[0]); 687 } else { 688 /* 689 * Two blocks are necessary. Save the first word 690 * after the other words. 691 */ 692 buf.param[0].kb_addr = &addr[2]; 693 buf.param[0].kb_size = i * sizeof(Elf_Word); 694 buf.param[1].kb_addr = &addr[1]; 695 buf.param[1].kb_size = sizeof(Elf_Word); 696 buf.newval[i] = first; 697 param = &buf.param[0]; 698 psize = 2 * sizeof(struct __kbind) + 699 (i + 1) * sizeof(buf.newval[0]); 700 } 701 } 702 703 /* directly code the syscall, so that it's actually inline here */ 704 { 705 register long syscall_num __asm("g1") = SYS_kbind; 706 register void *arg1 __asm("o0") = param; 707 register long arg2 __asm("o1") = psize; 708 register long arg3 __asm("o2") = cookie; 709 710 __asm volatile("t %2" : "+r" (arg1), "+r" (arg2) 711 : "i" (ST_SYSCALL), "r" (syscall_num), "r" (arg3) 712 : "cc", "memory"); 713 } 714 715 return newvalue; 716 } 717 718 /* 719 * Install rtld function call into this PLT slot. 720 */ 721 #define SAVE 0x9de3bf50 722 #define SETHI_l0 0x21000000 723 #define SETHI_l1 0x23000000 724 #define OR_l0_l0 0xa0142000 725 #define SLLX_l0_32_l0 0xa12c3020 726 #define OR_l0_l1_l0 0xa0140011 727 #define JMPL_l0_o1 0x93c42000 728 #define MOV_g1_o0 0x90100001 729 730 void 731 _dl_install_plt(Elf_Word *pltgot, Elf_Addr proc) 732 { 733 pltgot[0] = SAVE; 734 pltgot[1] = SETHI_l0 | HIVAL(proc, 42); 735 pltgot[2] = SETHI_l1 | HIVAL(proc, 10); 736 pltgot[3] = OR_l0_l0 | LOVAL((proc) >> 32); 737 pltgot[4] = SLLX_l0_32_l0; 738 pltgot[5] = OR_l0_l1_l0; 739 pltgot[6] = JMPL_l0_o1 | LOVAL(proc); 740 pltgot[7] = MOV_g1_o0; 741 } 742 743 void _dl_bind_start_0(long, long); 744 void _dl_bind_start_1(long, long); 745 746 static int 747 _dl_md_reloc_all_plt(elf_object_t *object) 748 { 749 long i; 750 long numrela; 751 int fails = 0; 752 Elf_Addr loff; 753 Elf_RelA *relas; 754 755 loff = object->obj_base; 756 numrela = object->Dyn.info[DT_PLTRELSZ] / sizeof(Elf_RelA); 757 relas = (Elf_RelA *)(object->Dyn.info[DT_JMPREL]); 758 759 if (relas == NULL) 760 return 0; 761 762 for (i = 0; i < numrela; i++, relas++) { 763 Elf_Addr value; 764 Elf_Word *where; 765 struct sym_res sr; 766 const Elf_Sym *sym; 767 768 if (ELF_R_TYPE(relas->r_info) != R_TYPE(JMP_SLOT)) 769 continue; 770 771 sym = object->dyn.symtab + ELF_R_SYM(relas->r_info); 772 773 sr = _dl_find_symbol(object->dyn.strtab + sym->st_name, 774 SYM_SEARCH_ALL|SYM_WARNNOTFOUND|SYM_PLT, 775 sym, object); 776 if (sr.sym == NULL) { 777 if (ELF_ST_BIND(sym->st_info) != STB_WEAK) 778 fails++; 779 continue; 780 } 781 782 where = (Elf_Word *)(relas->r_offset + loff); 783 value = sr.obj->obj_base + sr.sym->st_value; 784 785 if (__predict_false(relas->r_addend)) { 786 /* 787 * This entry is >32768. The relocation points to a 788 * PC-relative pointer to the _dl_bind_start_0 stub at 789 * the top of the PLT section. Update it to point to 790 * the target function. 791 */ 792 *(Elf_Addr *)where = relas->r_addend + value - 793 object->Dyn.info[DT_PLTGOT]; 794 } else 795 _dl_reloc_plt(&where[1], &where[2], where, value); 796 } 797 798 return fails; 799 } 800 801 /* 802 * Relocate the Global Offset Table (GOT). 803 */ 804 int 805 _dl_md_reloc_got(elf_object_t *object, int lazy) 806 { 807 int fails = 0; 808 Elf_Addr *pltgot = (Elf_Addr *)object->Dyn.info[DT_PLTGOT]; 809 Elf_Word *entry = (Elf_Word *)pltgot; 810 811 if (object->Dyn.info[DT_PLTREL] != DT_RELA) 812 return 0; 813 814 if (!lazy) { 815 fails = _dl_md_reloc_all_plt(object); 816 } else { 817 _dl_install_plt(&entry[0], (Elf_Addr)&_dl_bind_start_0); 818 _dl_install_plt(&entry[8], (Elf_Addr)&_dl_bind_start_1); 819 820 pltgot[8] = (Elf_Addr)object; 821 } 822 823 return fails; 824 } 825