1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 * Copyright 2017-2018 Mark Johnston <markj@FreeBSD.org> 26 */ 27 28 #include <sys/param.h> 29 #include <sys/mman.h> 30 #include <sys/wait.h> 31 32 #include <assert.h> 33 #include <elf.h> 34 #include <sys/types.h> 35 #include <fcntl.h> 36 #include <gelf.h> 37 #include <limits.h> 38 #include <stddef.h> 39 #include <stdio.h> 40 #include <stdlib.h> 41 #include <strings.h> 42 #include <errno.h> 43 #include <unistd.h> 44 45 #include <libelf.h> 46 47 #include <dt_impl.h> 48 #include <dt_provider.h> 49 #include <dt_program.h> 50 #include <dt_string.h> 51 52 #define ESHDR_NULL 0 53 #define ESHDR_SHSTRTAB 1 54 #define ESHDR_DOF 2 55 #define ESHDR_STRTAB 3 56 #define ESHDR_SYMTAB 4 57 #define ESHDR_REL 5 58 #define ESHDR_NUM 6 59 60 #define PWRITE_SCN(index, data) \ 61 (lseek64(fd, (off64_t)elf_file.shdr[(index)].sh_offset, SEEK_SET) != \ 62 (off64_t)elf_file.shdr[(index)].sh_offset || \ 63 dt_write(dtp, fd, (data), elf_file.shdr[(index)].sh_size) != \ 64 elf_file.shdr[(index)].sh_size) 65 66 static const char DTRACE_SHSTRTAB32[] = "\0" 67 ".shstrtab\0" /* 1 */ 68 ".SUNW_dof\0" /* 11 */ 69 ".strtab\0" /* 21 */ 70 ".symtab\0" /* 29 */ 71 ".rel.SUNW_dof"; /* 37 */ 72 73 static const char DTRACE_SHSTRTAB64[] = "\0" 74 ".shstrtab\0" /* 1 */ 75 ".SUNW_dof\0" /* 11 */ 76 ".strtab\0" /* 21 */ 77 ".symtab\0" /* 29 */ 78 ".rela.SUNW_dof"; /* 37 */ 79 80 static const char DOFSTR[] = "__SUNW_dof"; 81 static const char DOFLAZYSTR[] = "___SUNW_dof"; 82 83 typedef struct dt_link_pair { 84 struct dt_link_pair *dlp_next; /* next pair in linked list */ 85 void *dlp_str; /* buffer for string table */ 86 void *dlp_sym; /* buffer for symbol table */ 87 } dt_link_pair_t; 88 89 typedef struct dof_elf32 { 90 uint32_t de_nrel; /* relocation count */ 91 Elf32_Rel *de_rel; /* array of relocations for x86 */ 92 uint32_t de_nsym; /* symbol count */ 93 Elf32_Sym *de_sym; /* array of symbols */ 94 uint32_t de_strlen; /* size of of string table */ 95 char *de_strtab; /* string table */ 96 uint32_t de_global; /* index of the first global symbol */ 97 } dof_elf32_t; 98 99 static int 100 prepare_elf32(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf32_t *dep) 101 { 102 dof_sec_t *dofs, *s; 103 dof_relohdr_t *dofrh; 104 dof_relodesc_t *dofr; 105 char *strtab; 106 int i, j, nrel; 107 size_t strtabsz = 1; 108 uint32_t count = 0; 109 size_t base; 110 Elf32_Sym *sym; 111 Elf32_Rel *rel; 112 113 /*LINTED*/ 114 dofs = (dof_sec_t *)((char *)dof + dof->dofh_secoff); 115 116 /* 117 * First compute the size of the string table and the number of 118 * relocations present in the DOF. 119 */ 120 for (i = 0; i < dof->dofh_secnum; i++) { 121 if (dofs[i].dofs_type != DOF_SECT_URELHDR) 122 continue; 123 124 /*LINTED*/ 125 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset); 126 127 s = &dofs[dofrh->dofr_strtab]; 128 strtab = (char *)dof + s->dofs_offset; 129 assert(strtab[0] == '\0'); 130 strtabsz += s->dofs_size - 1; 131 132 s = &dofs[dofrh->dofr_relsec]; 133 /*LINTED*/ 134 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset); 135 count += s->dofs_size / s->dofs_entsize; 136 } 137 138 dep->de_strlen = strtabsz; 139 dep->de_nrel = count; 140 dep->de_nsym = count + 1; /* the first symbol is always null */ 141 142 if (dtp->dt_lazyload) { 143 dep->de_strlen += sizeof (DOFLAZYSTR); 144 dep->de_nsym++; 145 } else { 146 dep->de_strlen += sizeof (DOFSTR); 147 dep->de_nsym++; 148 } 149 150 if ((dep->de_rel = calloc(dep->de_nrel, 151 sizeof (dep->de_rel[0]))) == NULL) { 152 return (dt_set_errno(dtp, EDT_NOMEM)); 153 } 154 155 if ((dep->de_sym = calloc(dep->de_nsym, sizeof (Elf32_Sym))) == NULL) { 156 free(dep->de_rel); 157 return (dt_set_errno(dtp, EDT_NOMEM)); 158 } 159 160 if ((dep->de_strtab = calloc(dep->de_strlen, 1)) == NULL) { 161 free(dep->de_rel); 162 free(dep->de_sym); 163 return (dt_set_errno(dtp, EDT_NOMEM)); 164 } 165 166 count = 0; 167 strtabsz = 1; 168 dep->de_strtab[0] = '\0'; 169 rel = dep->de_rel; 170 sym = dep->de_sym; 171 dep->de_global = 1; 172 173 /* 174 * The first symbol table entry must be zeroed and is always ignored. 175 */ 176 bzero(sym, sizeof (Elf32_Sym)); 177 sym++; 178 179 /* 180 * Take a second pass through the DOF sections filling in the 181 * memory we allocated. 182 */ 183 for (i = 0; i < dof->dofh_secnum; i++) { 184 if (dofs[i].dofs_type != DOF_SECT_URELHDR) 185 continue; 186 187 /*LINTED*/ 188 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset); 189 190 s = &dofs[dofrh->dofr_strtab]; 191 strtab = (char *)dof + s->dofs_offset; 192 bcopy(strtab + 1, dep->de_strtab + strtabsz, s->dofs_size); 193 base = strtabsz; 194 strtabsz += s->dofs_size - 1; 195 196 s = &dofs[dofrh->dofr_relsec]; 197 /*LINTED*/ 198 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset); 199 nrel = s->dofs_size / s->dofs_entsize; 200 201 s = &dofs[dofrh->dofr_tgtsec]; 202 203 for (j = 0; j < nrel; j++) { 204 #if defined(__aarch64__) 205 rel->r_offset = s->dofs_offset + 206 dofr[j].dofr_offset; 207 rel->r_info = ELF32_R_INFO(count + dep->de_global, 208 R_ARM_REL32); 209 #elif defined(__arm__) 210 /* XXX */ 211 printf("%s:%s(%d): arm not implemented\n", 212 __FUNCTION__, __FILE__, __LINE__); 213 #elif defined(__i386) || defined(__amd64) 214 rel->r_offset = s->dofs_offset + 215 dofr[j].dofr_offset; 216 rel->r_info = ELF32_R_INFO(count + dep->de_global, 217 R_386_PC32); 218 #elif defined(__mips__) 219 /* XXX */ 220 printf("%s:%s(%d): MIPS not implemented\n", 221 __FUNCTION__, __FILE__, __LINE__); 222 #elif defined(__powerpc__) 223 /* 224 * Add 4 bytes to hit the low half of this 64-bit 225 * big-endian address. 226 */ 227 rel->r_offset = s->dofs_offset + 228 dofr[j].dofr_offset + 4; 229 rel->r_info = ELF32_R_INFO(count + dep->de_global, 230 R_PPC_REL32); 231 #elif defined(__riscv) 232 /* XXX */ 233 printf("%s:%s(%d): RISC-V not implemented\n", 234 __FUNCTION__, __FILE__, __LINE__); 235 #else 236 #error unknown ISA 237 #endif 238 239 sym->st_name = base + dofr[j].dofr_name - 1; 240 sym->st_value = 0; 241 sym->st_size = 0; 242 sym->st_info = ELF32_ST_INFO(STB_GLOBAL, STT_FUNC); 243 sym->st_other = ELF32_ST_VISIBILITY(STV_HIDDEN); 244 sym->st_shndx = SHN_UNDEF; 245 246 rel++; 247 sym++; 248 count++; 249 } 250 } 251 252 /* 253 * Add a symbol for the DOF itself. We use a different symbol for 254 * lazily and actively loaded DOF to make them easy to distinguish. 255 */ 256 sym->st_name = strtabsz; 257 sym->st_value = 0; 258 sym->st_size = dof->dofh_filesz; 259 sym->st_info = ELF32_ST_INFO(STB_GLOBAL, STT_OBJECT); 260 sym->st_other = ELF32_ST_VISIBILITY(STV_HIDDEN); 261 sym->st_shndx = ESHDR_DOF; 262 sym++; 263 264 if (dtp->dt_lazyload) { 265 bcopy(DOFLAZYSTR, dep->de_strtab + strtabsz, 266 sizeof (DOFLAZYSTR)); 267 strtabsz += sizeof (DOFLAZYSTR); 268 } else { 269 bcopy(DOFSTR, dep->de_strtab + strtabsz, sizeof (DOFSTR)); 270 strtabsz += sizeof (DOFSTR); 271 } 272 273 assert(count == dep->de_nrel); 274 assert(strtabsz == dep->de_strlen); 275 276 return (0); 277 } 278 279 280 typedef struct dof_elf64 { 281 uint32_t de_nrel; 282 Elf64_Rela *de_rel; 283 uint32_t de_nsym; 284 Elf64_Sym *de_sym; 285 286 uint32_t de_strlen; 287 char *de_strtab; 288 289 uint32_t de_global; 290 } dof_elf64_t; 291 292 static int 293 prepare_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf64_t *dep) 294 { 295 dof_sec_t *dofs, *s; 296 dof_relohdr_t *dofrh; 297 dof_relodesc_t *dofr; 298 char *strtab; 299 int i, j, nrel; 300 size_t strtabsz = 1; 301 uint64_t count = 0; 302 size_t base; 303 Elf64_Sym *sym; 304 Elf64_Rela *rel; 305 306 /*LINTED*/ 307 dofs = (dof_sec_t *)((char *)dof + dof->dofh_secoff); 308 309 /* 310 * First compute the size of the string table and the number of 311 * relocations present in the DOF. 312 */ 313 for (i = 0; i < dof->dofh_secnum; i++) { 314 if (dofs[i].dofs_type != DOF_SECT_URELHDR) 315 continue; 316 317 /*LINTED*/ 318 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset); 319 320 s = &dofs[dofrh->dofr_strtab]; 321 strtab = (char *)dof + s->dofs_offset; 322 assert(strtab[0] == '\0'); 323 strtabsz += s->dofs_size - 1; 324 325 s = &dofs[dofrh->dofr_relsec]; 326 /*LINTED*/ 327 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset); 328 count += s->dofs_size / s->dofs_entsize; 329 } 330 331 dep->de_strlen = strtabsz; 332 dep->de_nrel = count; 333 dep->de_nsym = count + 1; /* the first symbol is always null */ 334 335 if (dtp->dt_lazyload) { 336 dep->de_strlen += sizeof (DOFLAZYSTR); 337 dep->de_nsym++; 338 } else { 339 dep->de_strlen += sizeof (DOFSTR); 340 dep->de_nsym++; 341 } 342 343 if ((dep->de_rel = calloc(dep->de_nrel, 344 sizeof (dep->de_rel[0]))) == NULL) { 345 return (dt_set_errno(dtp, EDT_NOMEM)); 346 } 347 348 if ((dep->de_sym = calloc(dep->de_nsym, sizeof (Elf64_Sym))) == NULL) { 349 free(dep->de_rel); 350 return (dt_set_errno(dtp, EDT_NOMEM)); 351 } 352 353 if ((dep->de_strtab = calloc(dep->de_strlen, 1)) == NULL) { 354 free(dep->de_rel); 355 free(dep->de_sym); 356 return (dt_set_errno(dtp, EDT_NOMEM)); 357 } 358 359 count = 0; 360 strtabsz = 1; 361 dep->de_strtab[0] = '\0'; 362 rel = dep->de_rel; 363 sym = dep->de_sym; 364 dep->de_global = 1; 365 366 /* 367 * The first symbol table entry must be zeroed and is always ignored. 368 */ 369 bzero(sym, sizeof (Elf64_Sym)); 370 sym++; 371 372 /* 373 * Take a second pass through the DOF sections filling in the 374 * memory we allocated. 375 */ 376 for (i = 0; i < dof->dofh_secnum; i++) { 377 if (dofs[i].dofs_type != DOF_SECT_URELHDR) 378 continue; 379 380 /*LINTED*/ 381 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset); 382 383 s = &dofs[dofrh->dofr_strtab]; 384 strtab = (char *)dof + s->dofs_offset; 385 bcopy(strtab + 1, dep->de_strtab + strtabsz, s->dofs_size); 386 base = strtabsz; 387 strtabsz += s->dofs_size - 1; 388 389 s = &dofs[dofrh->dofr_relsec]; 390 /*LINTED*/ 391 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset); 392 nrel = s->dofs_size / s->dofs_entsize; 393 394 s = &dofs[dofrh->dofr_tgtsec]; 395 396 for (j = 0; j < nrel; j++) { 397 #if defined(__aarch64__) 398 rel->r_offset = s->dofs_offset + 399 dofr[j].dofr_offset; 400 rel->r_info = ELF64_R_INFO(count + dep->de_global, 401 R_AARCH64_PREL64); 402 #elif defined(__arm__) 403 /* XXX */ 404 #elif defined(__mips__) 405 /* XXX */ 406 #elif defined(__powerpc__) 407 rel->r_offset = s->dofs_offset + 408 dofr[j].dofr_offset; 409 rel->r_info = ELF64_R_INFO(count + dep->de_global, 410 R_PPC64_REL64); 411 #elif defined(__riscv) 412 /* XXX */ 413 #elif defined(__i386) || defined(__amd64) 414 rel->r_offset = s->dofs_offset + 415 dofr[j].dofr_offset; 416 rel->r_info = ELF64_R_INFO(count + dep->de_global, 417 R_X86_64_PC64); 418 #else 419 #error unknown ISA 420 #endif 421 422 sym->st_name = base + dofr[j].dofr_name - 1; 423 sym->st_value = 0; 424 sym->st_size = 0; 425 sym->st_info = GELF_ST_INFO(STB_GLOBAL, STT_FUNC); 426 sym->st_other = ELF64_ST_VISIBILITY(STV_HIDDEN); 427 sym->st_shndx = SHN_UNDEF; 428 429 rel++; 430 sym++; 431 count++; 432 } 433 } 434 435 /* 436 * Add a symbol for the DOF itself. We use a different symbol for 437 * lazily and actively loaded DOF to make them easy to distinguish. 438 */ 439 sym->st_name = strtabsz; 440 sym->st_value = 0; 441 sym->st_size = dof->dofh_filesz; 442 sym->st_info = GELF_ST_INFO(STB_GLOBAL, STT_OBJECT); 443 sym->st_other = ELF64_ST_VISIBILITY(STV_HIDDEN); 444 sym->st_shndx = ESHDR_DOF; 445 sym++; 446 447 if (dtp->dt_lazyload) { 448 bcopy(DOFLAZYSTR, dep->de_strtab + strtabsz, 449 sizeof (DOFLAZYSTR)); 450 strtabsz += sizeof (DOFLAZYSTR); 451 } else { 452 bcopy(DOFSTR, dep->de_strtab + strtabsz, sizeof (DOFSTR)); 453 strtabsz += sizeof (DOFSTR); 454 } 455 456 assert(count == dep->de_nrel); 457 assert(strtabsz == dep->de_strlen); 458 459 return (0); 460 } 461 462 /* 463 * Write out an ELF32 file prologue consisting of a header, section headers, 464 * and a section header string table. The DOF data will follow this prologue 465 * and complete the contents of the given ELF file. 466 */ 467 static int 468 dump_elf32(dtrace_hdl_t *dtp, const dof_hdr_t *dof, int fd) 469 { 470 struct { 471 Elf32_Ehdr ehdr; 472 Elf32_Shdr shdr[ESHDR_NUM]; 473 } elf_file; 474 475 Elf32_Shdr *shp; 476 Elf32_Off off; 477 dof_elf32_t de; 478 int ret = 0; 479 uint_t nshdr; 480 481 if (prepare_elf32(dtp, dof, &de) != 0) 482 return (-1); /* errno is set for us */ 483 484 /* 485 * If there are no relocations, we only need enough sections for 486 * the shstrtab and the DOF. 487 */ 488 nshdr = de.de_nrel == 0 ? ESHDR_SYMTAB + 1 : ESHDR_NUM; 489 490 bzero(&elf_file, sizeof (elf_file)); 491 492 elf_file.ehdr.e_ident[EI_MAG0] = ELFMAG0; 493 elf_file.ehdr.e_ident[EI_MAG1] = ELFMAG1; 494 elf_file.ehdr.e_ident[EI_MAG2] = ELFMAG2; 495 elf_file.ehdr.e_ident[EI_MAG3] = ELFMAG3; 496 elf_file.ehdr.e_ident[EI_VERSION] = EV_CURRENT; 497 elf_file.ehdr.e_ident[EI_CLASS] = ELFCLASS32; 498 #if BYTE_ORDER == _BIG_ENDIAN 499 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2MSB; 500 #else 501 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2LSB; 502 #endif 503 elf_file.ehdr.e_ident[EI_OSABI] = ELFOSABI_FREEBSD; 504 elf_file.ehdr.e_type = ET_REL; 505 #if defined(__arm__) 506 elf_file.ehdr.e_machine = EM_ARM; 507 #elif defined(__mips__) 508 elf_file.ehdr.e_machine = EM_MIPS; 509 #elif defined(__powerpc__) 510 elf_file.ehdr.e_machine = EM_PPC; 511 #elif defined(__i386) || defined(__amd64) 512 elf_file.ehdr.e_machine = EM_386; 513 #elif defined(__aarch64__) 514 elf_file.ehdr.e_machine = EM_AARCH64; 515 #endif 516 elf_file.ehdr.e_version = EV_CURRENT; 517 elf_file.ehdr.e_shoff = sizeof (Elf32_Ehdr); 518 elf_file.ehdr.e_ehsize = sizeof (Elf32_Ehdr); 519 elf_file.ehdr.e_phentsize = sizeof (Elf32_Phdr); 520 elf_file.ehdr.e_shentsize = sizeof (Elf32_Shdr); 521 elf_file.ehdr.e_shnum = nshdr; 522 elf_file.ehdr.e_shstrndx = ESHDR_SHSTRTAB; 523 off = sizeof (elf_file) + nshdr * sizeof (Elf32_Shdr); 524 525 shp = &elf_file.shdr[ESHDR_SHSTRTAB]; 526 shp->sh_name = 1; /* DTRACE_SHSTRTAB32[1] = ".shstrtab" */ 527 shp->sh_type = SHT_STRTAB; 528 shp->sh_offset = off; 529 shp->sh_size = sizeof (DTRACE_SHSTRTAB32); 530 shp->sh_addralign = sizeof (char); 531 off = roundup2(shp->sh_offset + shp->sh_size, 8); 532 533 shp = &elf_file.shdr[ESHDR_DOF]; 534 shp->sh_name = 11; /* DTRACE_SHSTRTAB32[11] = ".SUNW_dof" */ 535 shp->sh_flags = SHF_ALLOC; 536 shp->sh_type = SHT_SUNW_dof; 537 shp->sh_offset = off; 538 shp->sh_size = dof->dofh_filesz; 539 shp->sh_addralign = 8; 540 off = shp->sh_offset + shp->sh_size; 541 542 shp = &elf_file.shdr[ESHDR_STRTAB]; 543 shp->sh_name = 21; /* DTRACE_SHSTRTAB32[21] = ".strtab" */ 544 shp->sh_flags = SHF_ALLOC; 545 shp->sh_type = SHT_STRTAB; 546 shp->sh_offset = off; 547 shp->sh_size = de.de_strlen; 548 shp->sh_addralign = sizeof (char); 549 off = roundup2(shp->sh_offset + shp->sh_size, 4); 550 551 shp = &elf_file.shdr[ESHDR_SYMTAB]; 552 shp->sh_name = 29; /* DTRACE_SHSTRTAB32[29] = ".symtab" */ 553 shp->sh_flags = SHF_ALLOC; 554 shp->sh_type = SHT_SYMTAB; 555 shp->sh_entsize = sizeof (Elf32_Sym); 556 shp->sh_link = ESHDR_STRTAB; 557 shp->sh_offset = off; 558 shp->sh_info = de.de_global; 559 shp->sh_size = de.de_nsym * sizeof (Elf32_Sym); 560 shp->sh_addralign = 4; 561 off = roundup2(shp->sh_offset + shp->sh_size, 4); 562 563 if (de.de_nrel == 0) { 564 if (dt_write(dtp, fd, &elf_file, 565 sizeof (elf_file)) != sizeof (elf_file) || 566 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB32) || 567 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) || 568 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) || 569 PWRITE_SCN(ESHDR_DOF, dof)) { 570 ret = dt_set_errno(dtp, errno); 571 } 572 } else { 573 shp = &elf_file.shdr[ESHDR_REL]; 574 shp->sh_name = 37; /* DTRACE_SHSTRTAB32[37] = ".rel.SUNW_dof" */ 575 shp->sh_flags = SHF_ALLOC; 576 shp->sh_type = SHT_REL; 577 shp->sh_entsize = sizeof (de.de_rel[0]); 578 shp->sh_link = ESHDR_SYMTAB; 579 shp->sh_info = ESHDR_DOF; 580 shp->sh_offset = off; 581 shp->sh_size = de.de_nrel * sizeof (de.de_rel[0]); 582 shp->sh_addralign = 4; 583 584 if (dt_write(dtp, fd, &elf_file, 585 sizeof (elf_file)) != sizeof (elf_file) || 586 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB32) || 587 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) || 588 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) || 589 PWRITE_SCN(ESHDR_REL, de.de_rel) || 590 PWRITE_SCN(ESHDR_DOF, dof)) { 591 ret = dt_set_errno(dtp, errno); 592 } 593 } 594 595 free(de.de_strtab); 596 free(de.de_sym); 597 free(de.de_rel); 598 599 return (ret); 600 } 601 602 /* 603 * Write out an ELF64 file prologue consisting of a header, section headers, 604 * and a section header string table. The DOF data will follow this prologue 605 * and complete the contents of the given ELF file. 606 */ 607 static int 608 dump_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, int fd) 609 { 610 struct { 611 Elf64_Ehdr ehdr; 612 Elf64_Shdr shdr[ESHDR_NUM]; 613 } elf_file; 614 615 Elf64_Shdr *shp; 616 Elf64_Off off; 617 dof_elf64_t de; 618 int ret = 0; 619 uint_t nshdr; 620 621 if (prepare_elf64(dtp, dof, &de) != 0) 622 return (-1); /* errno is set for us */ 623 624 /* 625 * If there are no relocations, we only need enough sections for 626 * the shstrtab and the DOF. 627 */ 628 nshdr = de.de_nrel == 0 ? ESHDR_SYMTAB + 1 : ESHDR_NUM; 629 630 bzero(&elf_file, sizeof (elf_file)); 631 632 elf_file.ehdr.e_ident[EI_MAG0] = ELFMAG0; 633 elf_file.ehdr.e_ident[EI_MAG1] = ELFMAG1; 634 elf_file.ehdr.e_ident[EI_MAG2] = ELFMAG2; 635 elf_file.ehdr.e_ident[EI_MAG3] = ELFMAG3; 636 elf_file.ehdr.e_ident[EI_VERSION] = EV_CURRENT; 637 elf_file.ehdr.e_ident[EI_CLASS] = ELFCLASS64; 638 #if BYTE_ORDER == _BIG_ENDIAN 639 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2MSB; 640 #else 641 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2LSB; 642 #endif 643 elf_file.ehdr.e_ident[EI_OSABI] = ELFOSABI_FREEBSD; 644 elf_file.ehdr.e_type = ET_REL; 645 #if defined(__arm__) 646 elf_file.ehdr.e_machine = EM_ARM; 647 #elif defined(__mips__) 648 elf_file.ehdr.e_machine = EM_MIPS; 649 #elif defined(__powerpc64__) 650 #if defined(_CALL_ELF) && _CALL_ELF == 2 651 elf_file.ehdr.e_flags = 2; 652 #endif 653 elf_file.ehdr.e_machine = EM_PPC64; 654 #elif defined(__i386) || defined(__amd64) 655 elf_file.ehdr.e_machine = EM_AMD64; 656 #elif defined(__aarch64__) 657 elf_file.ehdr.e_machine = EM_AARCH64; 658 #endif 659 elf_file.ehdr.e_version = EV_CURRENT; 660 elf_file.ehdr.e_shoff = sizeof (Elf64_Ehdr); 661 elf_file.ehdr.e_ehsize = sizeof (Elf64_Ehdr); 662 elf_file.ehdr.e_phentsize = sizeof (Elf64_Phdr); 663 elf_file.ehdr.e_shentsize = sizeof (Elf64_Shdr); 664 elf_file.ehdr.e_shnum = nshdr; 665 elf_file.ehdr.e_shstrndx = ESHDR_SHSTRTAB; 666 off = sizeof (elf_file) + nshdr * sizeof (Elf64_Shdr); 667 668 shp = &elf_file.shdr[ESHDR_SHSTRTAB]; 669 shp->sh_name = 1; /* DTRACE_SHSTRTAB64[1] = ".shstrtab" */ 670 shp->sh_type = SHT_STRTAB; 671 shp->sh_offset = off; 672 shp->sh_size = sizeof (DTRACE_SHSTRTAB64); 673 shp->sh_addralign = sizeof (char); 674 off = roundup2(shp->sh_offset + shp->sh_size, 8); 675 676 shp = &elf_file.shdr[ESHDR_DOF]; 677 shp->sh_name = 11; /* DTRACE_SHSTRTAB64[11] = ".SUNW_dof" */ 678 shp->sh_flags = SHF_ALLOC; 679 shp->sh_type = SHT_SUNW_dof; 680 shp->sh_offset = off; 681 shp->sh_size = dof->dofh_filesz; 682 shp->sh_addralign = 8; 683 off = shp->sh_offset + shp->sh_size; 684 685 shp = &elf_file.shdr[ESHDR_STRTAB]; 686 shp->sh_name = 21; /* DTRACE_SHSTRTAB64[21] = ".strtab" */ 687 shp->sh_flags = SHF_ALLOC; 688 shp->sh_type = SHT_STRTAB; 689 shp->sh_offset = off; 690 shp->sh_size = de.de_strlen; 691 shp->sh_addralign = sizeof (char); 692 off = roundup2(shp->sh_offset + shp->sh_size, 8); 693 694 shp = &elf_file.shdr[ESHDR_SYMTAB]; 695 shp->sh_name = 29; /* DTRACE_SHSTRTAB64[29] = ".symtab" */ 696 shp->sh_flags = SHF_ALLOC; 697 shp->sh_type = SHT_SYMTAB; 698 shp->sh_entsize = sizeof (Elf64_Sym); 699 shp->sh_link = ESHDR_STRTAB; 700 shp->sh_offset = off; 701 shp->sh_info = de.de_global; 702 shp->sh_size = de.de_nsym * sizeof (Elf64_Sym); 703 shp->sh_addralign = 8; 704 off = roundup2(shp->sh_offset + shp->sh_size, 8); 705 706 if (de.de_nrel == 0) { 707 if (dt_write(dtp, fd, &elf_file, 708 sizeof (elf_file)) != sizeof (elf_file) || 709 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB64) || 710 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) || 711 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) || 712 PWRITE_SCN(ESHDR_DOF, dof)) { 713 ret = dt_set_errno(dtp, errno); 714 } 715 } else { 716 shp = &elf_file.shdr[ESHDR_REL]; 717 shp->sh_name = 37; /* DTRACE_SHSTRTAB64[37] = ".rel.SUNW_dof" */ 718 shp->sh_flags = SHF_ALLOC; 719 shp->sh_type = SHT_RELA; 720 shp->sh_entsize = sizeof (de.de_rel[0]); 721 shp->sh_link = ESHDR_SYMTAB; 722 shp->sh_info = ESHDR_DOF; 723 shp->sh_offset = off; 724 shp->sh_size = de.de_nrel * sizeof (de.de_rel[0]); 725 shp->sh_addralign = 8; 726 727 if (dt_write(dtp, fd, &elf_file, 728 sizeof (elf_file)) != sizeof (elf_file) || 729 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB64) || 730 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) || 731 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) || 732 PWRITE_SCN(ESHDR_REL, de.de_rel) || 733 PWRITE_SCN(ESHDR_DOF, dof)) { 734 ret = dt_set_errno(dtp, errno); 735 } 736 } 737 738 free(de.de_strtab); 739 free(de.de_sym); 740 free(de.de_rel); 741 742 return (ret); 743 } 744 745 static int 746 dt_symtab_lookup(Elf_Data *data_sym, int start, int end, uintptr_t addr, 747 uint_t shn, GElf_Sym *sym, int uses_funcdesc, Elf *elf) 748 { 749 Elf64_Addr symval; 750 Elf_Scn *opd_scn; 751 Elf_Data *opd_desc; 752 int i; 753 754 for (i = start; i < end && gelf_getsym(data_sym, i, sym) != NULL; i++) { 755 if (GELF_ST_TYPE(sym->st_info) == STT_FUNC) { 756 symval = sym->st_value; 757 if (uses_funcdesc) { 758 opd_scn = elf_getscn(elf, sym->st_shndx); 759 opd_desc = elf_rawdata(opd_scn, NULL); 760 symval = 761 *(uint64_t*)((char *)opd_desc->d_buf + symval); 762 } 763 if ((uses_funcdesc || shn == sym->st_shndx) && 764 symval <= addr && addr < symval + sym->st_size) 765 return (0); 766 } 767 } 768 769 return (-1); 770 } 771 772 #if defined(__aarch64__) 773 #define DT_OP_NOP 0xd503201f 774 #define DT_OP_RET 0xd65f03c0 775 #define DT_OP_CALL26 0x94000000 776 #define DT_OP_JUMP26 0x14000000 777 #define DT_REL_NONE R_AARCH64_NONE 778 779 static int 780 dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela, 781 uint32_t *off) 782 { 783 uint32_t *ip; 784 785 /* 786 * Ensure that the offset is aligned on an instruction boundary. 787 */ 788 if ((rela->r_offset & (sizeof (uint32_t) - 1)) != 0) 789 return (-1); 790 791 /* 792 * We only know about some specific relocation types. 793 * We also recognize relocation type NONE, since that gets used for 794 * relocations of USDT probes, and we might be re-processing a file. 795 */ 796 if (GELF_R_TYPE(rela->r_info) != R_AARCH64_CALL26 && 797 GELF_R_TYPE(rela->r_info) != R_AARCH64_JUMP26 && 798 GELF_R_TYPE(rela->r_info) != R_AARCH64_NONE) 799 return (-1); 800 801 ip = (uint32_t *)(p + rela->r_offset); 802 803 /* 804 * We may have already processed this object file in an earlier linker 805 * invocation. Check to see if the present instruction sequence matches 806 * the one we would install below. 807 */ 808 if (ip[0] == DT_OP_NOP || ip[0] == DT_OP_RET) 809 return (0); 810 811 /* 812 * We only expect call instructions with a displacement of 0, or a jump 813 * instruction acting as a tail call. 814 */ 815 if (ip[0] != DT_OP_CALL26 && ip[0] != DT_OP_JUMP26) { 816 dt_dprintf("found %x instead of a call or jmp instruction at " 817 "%llx\n", ip[0], (u_longlong_t)rela->r_offset); 818 return (-1); 819 } 820 821 /* 822 * On arm64, we do not have to differentiate between regular probes and 823 * is-enabled probes. Both cases are encoded as a regular branch for 824 * non-tail call locations, and a jump for tail call locations. Calls 825 * are to be converted into a no-op whereas jumps should become a 826 * return. 827 */ 828 if (ip[0] == DT_OP_CALL26) 829 ip[0] = DT_OP_NOP; 830 else 831 ip[0] = DT_OP_RET; 832 833 return (0); 834 } 835 #elif defined(__arm__) 836 #define DT_REL_NONE R_ARM_NONE 837 838 static int 839 dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela, 840 uint32_t *off) 841 { 842 printf("%s:%s(%d): arm not implemented\n", __FUNCTION__, __FILE__, 843 __LINE__); 844 return (-1); 845 } 846 #elif defined(__mips__) 847 #define DT_REL_NONE R_MIPS_NONE 848 849 static int 850 dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela, 851 uint32_t *off) 852 { 853 printf("%s:%s(%d): MIPS not implemented\n", __FUNCTION__, __FILE__, 854 __LINE__); 855 return (-1); 856 } 857 #elif defined(__powerpc__) 858 /* The sentinel is 'xor r3,r3,r3'. */ 859 #define DT_OP_XOR_R3 0x7c631a78 860 861 #define DT_OP_NOP 0x60000000 862 #define DT_OP_BLR 0x4e800020 863 864 /* This captures all forms of branching to address. */ 865 #define DT_IS_BRANCH(inst) ((inst & 0xfc000000) == 0x48000000) 866 #define DT_IS_BL(inst) (DT_IS_BRANCH(inst) && (inst & 0x01)) 867 868 #define DT_REL_NONE R_PPC_NONE 869 870 static int 871 dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela, 872 uint32_t *off) 873 { 874 uint32_t *ip; 875 876 if ((rela->r_offset & (sizeof (uint32_t) - 1)) != 0) 877 return (-1); 878 879 /*LINTED*/ 880 ip = (uint32_t *)(p + rela->r_offset); 881 882 /* 883 * We only know about some specific relocation types. 884 */ 885 if (GELF_R_TYPE(rela->r_info) != R_PPC_REL24 && 886 GELF_R_TYPE(rela->r_info) != R_PPC_PLTREL24 && 887 GELF_R_TYPE(rela->r_info) != R_PPC_NONE) 888 return (-1); 889 890 /* 891 * We may have already processed this object file in an earlier linker 892 * invocation. Check to see if the present instruction sequence matches 893 * the one we would install below. 894 */ 895 if (isenabled) { 896 if (ip[0] == DT_OP_XOR_R3) { 897 (*off) += sizeof (ip[0]); 898 return (0); 899 } 900 } else { 901 if (ip[0] == DT_OP_NOP) { 902 (*off) += sizeof (ip[0]); 903 return (0); 904 } 905 } 906 907 /* 908 * We only expect branch to address instructions. 909 */ 910 if (!DT_IS_BRANCH(ip[0])) { 911 dt_dprintf("found %x instead of a branch instruction at %llx\n", 912 ip[0], (u_longlong_t)rela->r_offset); 913 return (-1); 914 } 915 916 if (isenabled) { 917 /* 918 * It would necessarily indicate incorrect usage if an is- 919 * enabled probe were tail-called so flag that as an error. 920 * It's also potentially (very) tricky to handle gracefully, 921 * but could be done if this were a desired use scenario. 922 */ 923 if (!DT_IS_BL(ip[0])) { 924 dt_dprintf("tail call to is-enabled probe at %llx\n", 925 (u_longlong_t)rela->r_offset); 926 return (-1); 927 } 928 929 ip[0] = DT_OP_XOR_R3; 930 (*off) += sizeof (ip[0]); 931 } else { 932 if (DT_IS_BL(ip[0])) 933 ip[0] = DT_OP_NOP; 934 else 935 ip[0] = DT_OP_BLR; 936 } 937 938 return (0); 939 } 940 #elif defined(__riscv) 941 #define DT_REL_NONE R_RISCV_NONE 942 static int 943 dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela, 944 uint32_t *off) 945 { 946 printf("%s:%s(%d): RISC-V implementation required\n", __FUNCTION__, 947 __FILE__, __LINE__); 948 return (-1); 949 } 950 951 #elif defined(__i386) || defined(__amd64) 952 953 #define DT_OP_NOP 0x90 954 #define DT_OP_RET 0xc3 955 #define DT_OP_CALL 0xe8 956 #define DT_OP_JMP32 0xe9 957 #define DT_OP_REX_RAX 0x48 958 #define DT_OP_XOR_EAX_0 0x33 959 #define DT_OP_XOR_EAX_1 0xc0 960 961 #define DT_REL_NONE R_386_NONE 962 963 static int 964 dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela, 965 uint32_t *off) 966 { 967 uint8_t *ip = (uint8_t *)(p + rela->r_offset - 1); 968 uint8_t ret; 969 970 /* 971 * On x86, the first byte of the instruction is the call opcode and 972 * the next four bytes are the 32-bit address; the relocation is for 973 * the address operand. We back up the offset to the first byte of 974 * the instruction. For is-enabled probes, we later advance the offset 975 * so that it hits the first nop in the instruction sequence. 976 */ 977 (*off) -= 1; 978 979 /* 980 * We only know about some specific relocation types. Luckily 981 * these types have the same values on both 32-bit and 64-bit 982 * x86 architectures. 983 */ 984 if (GELF_R_TYPE(rela->r_info) != R_386_PC32 && 985 GELF_R_TYPE(rela->r_info) != R_386_PLT32 && 986 GELF_R_TYPE(rela->r_info) != R_386_NONE) 987 return (-1); 988 989 /* 990 * We may have already processed this object file in an earlier linker 991 * invocation. Check to see if the present instruction sequence matches 992 * the one we would install. For is-enabled probes, we advance the 993 * offset to the first nop instruction in the sequence to match the 994 * text modification code below. 995 */ 996 if (!isenabled) { 997 if ((ip[0] == DT_OP_NOP || ip[0] == DT_OP_RET) && 998 ip[1] == DT_OP_NOP && ip[2] == DT_OP_NOP && 999 ip[3] == DT_OP_NOP && ip[4] == DT_OP_NOP) 1000 return (0); 1001 } else if (dtp->dt_oflags & DTRACE_O_LP64) { 1002 if (ip[0] == DT_OP_REX_RAX && 1003 ip[1] == DT_OP_XOR_EAX_0 && ip[2] == DT_OP_XOR_EAX_1 && 1004 (ip[3] == DT_OP_NOP || ip[3] == DT_OP_RET) && 1005 ip[4] == DT_OP_NOP) { 1006 (*off) += 3; 1007 return (0); 1008 } 1009 } else { 1010 if (ip[0] == DT_OP_XOR_EAX_0 && ip[1] == DT_OP_XOR_EAX_1 && 1011 (ip[2] == DT_OP_NOP || ip[2] == DT_OP_RET) && 1012 ip[3] == DT_OP_NOP && ip[4] == DT_OP_NOP) { 1013 (*off) += 2; 1014 return (0); 1015 } 1016 } 1017 1018 /* 1019 * We expect either a call instrution with a 32-bit displacement or a 1020 * jmp instruction with a 32-bit displacement acting as a tail-call. 1021 */ 1022 if (ip[0] != DT_OP_CALL && ip[0] != DT_OP_JMP32) { 1023 dt_dprintf("found %x instead of a call or jmp instruction at " 1024 "%llx\n", ip[0], (u_longlong_t)rela->r_offset); 1025 return (-1); 1026 } 1027 1028 ret = (ip[0] == DT_OP_JMP32) ? DT_OP_RET : DT_OP_NOP; 1029 1030 /* 1031 * Establish the instruction sequence -- all nops for probes, and an 1032 * instruction to clear the return value register (%eax/%rax) followed 1033 * by nops for is-enabled probes. For is-enabled probes, we advance 1034 * the offset to the first nop. This isn't stricly necessary but makes 1035 * for more readable disassembly when the probe is enabled. 1036 */ 1037 if (!isenabled) { 1038 ip[0] = ret; 1039 ip[1] = DT_OP_NOP; 1040 ip[2] = DT_OP_NOP; 1041 ip[3] = DT_OP_NOP; 1042 ip[4] = DT_OP_NOP; 1043 } else if (dtp->dt_oflags & DTRACE_O_LP64) { 1044 ip[0] = DT_OP_REX_RAX; 1045 ip[1] = DT_OP_XOR_EAX_0; 1046 ip[2] = DT_OP_XOR_EAX_1; 1047 ip[3] = ret; 1048 ip[4] = DT_OP_NOP; 1049 (*off) += 3; 1050 } else { 1051 ip[0] = DT_OP_XOR_EAX_0; 1052 ip[1] = DT_OP_XOR_EAX_1; 1053 ip[2] = ret; 1054 ip[3] = DT_OP_NOP; 1055 ip[4] = DT_OP_NOP; 1056 (*off) += 2; 1057 } 1058 1059 return (0); 1060 } 1061 1062 #else 1063 #error unknown ISA 1064 #endif 1065 1066 /*PRINTFLIKE5*/ 1067 static int 1068 dt_link_error(dtrace_hdl_t *dtp, Elf *elf, int fd, dt_link_pair_t *bufs, 1069 const char *format, ...) 1070 { 1071 va_list ap; 1072 dt_link_pair_t *pair; 1073 1074 va_start(ap, format); 1075 dt_set_errmsg(dtp, NULL, NULL, NULL, 0, format, ap); 1076 va_end(ap); 1077 1078 if (elf != NULL) 1079 (void) elf_end(elf); 1080 1081 if (fd >= 0) 1082 (void) close(fd); 1083 1084 while ((pair = bufs) != NULL) { 1085 bufs = pair->dlp_next; 1086 dt_free(dtp, pair->dlp_str); 1087 dt_free(dtp, pair->dlp_sym); 1088 dt_free(dtp, pair); 1089 } 1090 1091 return (dt_set_errno(dtp, EDT_COMPILER)); 1092 } 1093 1094 /* 1095 * Provide a unique identifier used when adding global symbols to an object. 1096 * This is the FNV-1a hash of an absolute path for the file. 1097 */ 1098 static unsigned int 1099 hash_obj(const char *obj, int fd) 1100 { 1101 char path[PATH_MAX]; 1102 unsigned int h; 1103 1104 if (realpath(obj, path) == NULL) 1105 return (-1); 1106 1107 for (h = 2166136261u, obj = &path[0]; *obj != '\0'; obj++) 1108 h = (h ^ *obj) * 16777619; 1109 h &= 0x7fffffff; 1110 return (h); 1111 } 1112 1113 static int 1114 process_obj(dtrace_hdl_t *dtp, const char *obj, int *eprobesp) 1115 { 1116 static const char dt_prefix[] = "__dtrace"; 1117 static const char dt_enabled[] = "enabled"; 1118 static const char dt_symprefix[] = "$dtrace"; 1119 static const char dt_symfmt[] = "%s%u.%s"; 1120 static const char dt_weaksymfmt[] = "%s.%s"; 1121 char probename[DTRACE_NAMELEN]; 1122 int fd, i, ndx, eprobe, uses_funcdesc = 0, mod = 0; 1123 Elf *elf = NULL; 1124 GElf_Ehdr ehdr; 1125 Elf_Scn *scn_rel, *scn_sym, *scn_str, *scn_tgt; 1126 Elf_Data *data_rel, *data_sym, *data_str, *data_tgt; 1127 GElf_Shdr shdr_rel, shdr_sym, shdr_str, shdr_tgt; 1128 GElf_Sym rsym, fsym, dsym; 1129 GElf_Rela rela; 1130 char *s, *p, *r; 1131 char pname[DTRACE_PROVNAMELEN]; 1132 dt_provider_t *pvp; 1133 dt_probe_t *prp; 1134 uint32_t off, eclass, emachine1, emachine2; 1135 size_t symsize, osym, nsym, isym, istr, len; 1136 unsigned int objkey; 1137 dt_link_pair_t *pair, *bufs = NULL; 1138 dt_strtab_t *strtab; 1139 void *tmp; 1140 1141 if ((fd = open64(obj, O_RDWR)) == -1) { 1142 return (dt_link_error(dtp, elf, fd, bufs, 1143 "failed to open %s: %s", obj, strerror(errno))); 1144 } 1145 1146 if ((elf = elf_begin(fd, ELF_C_RDWR, NULL)) == NULL) { 1147 return (dt_link_error(dtp, elf, fd, bufs, 1148 "failed to process %s: %s", obj, elf_errmsg(elf_errno()))); 1149 } 1150 1151 switch (elf_kind(elf)) { 1152 case ELF_K_ELF: 1153 break; 1154 case ELF_K_AR: 1155 return (dt_link_error(dtp, elf, fd, bufs, "archives are not " 1156 "permitted; use the contents of the archive instead: %s", 1157 obj)); 1158 default: 1159 return (dt_link_error(dtp, elf, fd, bufs, 1160 "invalid file type: %s", obj)); 1161 } 1162 1163 if (gelf_getehdr(elf, &ehdr) == NULL) { 1164 return (dt_link_error(dtp, elf, fd, bufs, "corrupt file: %s", 1165 obj)); 1166 } 1167 1168 if (dtp->dt_oflags & DTRACE_O_LP64) { 1169 eclass = ELFCLASS64; 1170 #if defined(__mips__) 1171 emachine1 = emachine2 = EM_MIPS; 1172 #elif defined(__powerpc__) 1173 emachine1 = emachine2 = EM_PPC64; 1174 #if !defined(_CALL_ELF) || _CALL_ELF == 1 1175 uses_funcdesc = 1; 1176 #endif 1177 #elif defined(__i386) || defined(__amd64) 1178 emachine1 = emachine2 = EM_AMD64; 1179 #elif defined(__aarch64__) 1180 emachine1 = emachine2 = EM_AARCH64; 1181 #endif 1182 symsize = sizeof (Elf64_Sym); 1183 } else { 1184 eclass = ELFCLASS32; 1185 #if defined(__arm__) 1186 emachine1 = emachine2 = EM_ARM; 1187 #elif defined(__mips__) 1188 emachine1 = emachine2 = EM_MIPS; 1189 #elif defined(__powerpc__) 1190 emachine1 = emachine2 = EM_PPC; 1191 #elif defined(__i386) || defined(__amd64) 1192 emachine1 = emachine2 = EM_386; 1193 #endif 1194 symsize = sizeof (Elf32_Sym); 1195 } 1196 1197 if (ehdr.e_ident[EI_CLASS] != eclass) { 1198 return (dt_link_error(dtp, elf, fd, bufs, 1199 "incorrect ELF class for object file: %s", obj)); 1200 } 1201 1202 if (ehdr.e_machine != emachine1 && ehdr.e_machine != emachine2) { 1203 return (dt_link_error(dtp, elf, fd, bufs, 1204 "incorrect ELF machine type for object file: %s", obj)); 1205 } 1206 1207 /* 1208 * We use this token as a relatively unique handle for this file on the 1209 * system in order to disambiguate potential conflicts between files of 1210 * the same name which contain identially named local symbols. 1211 */ 1212 if ((objkey = hash_obj(obj, fd)) == (unsigned int)-1) 1213 return (dt_link_error(dtp, elf, fd, bufs, 1214 "failed to generate unique key for object file: %s", obj)); 1215 1216 scn_rel = NULL; 1217 while ((scn_rel = elf_nextscn(elf, scn_rel)) != NULL) { 1218 if (gelf_getshdr(scn_rel, &shdr_rel) == NULL) 1219 goto err; 1220 1221 /* 1222 * Skip any non-relocation sections. 1223 */ 1224 if (shdr_rel.sh_type != SHT_RELA && shdr_rel.sh_type != SHT_REL) 1225 continue; 1226 1227 if ((data_rel = elf_getdata(scn_rel, NULL)) == NULL) 1228 goto err; 1229 1230 /* 1231 * Grab the section, section header and section data for the 1232 * symbol table that this relocation section references. 1233 */ 1234 if ((scn_sym = elf_getscn(elf, shdr_rel.sh_link)) == NULL || 1235 gelf_getshdr(scn_sym, &shdr_sym) == NULL || 1236 (data_sym = elf_getdata(scn_sym, NULL)) == NULL) 1237 goto err; 1238 1239 /* 1240 * Ditto for that symbol table's string table. 1241 */ 1242 if ((scn_str = elf_getscn(elf, shdr_sym.sh_link)) == NULL || 1243 gelf_getshdr(scn_str, &shdr_str) == NULL || 1244 (data_str = elf_getdata(scn_str, NULL)) == NULL) 1245 goto err; 1246 1247 /* 1248 * Grab the section, section header and section data for the 1249 * target section for the relocations. For the relocations 1250 * we're looking for -- this will typically be the text of the 1251 * object file. 1252 */ 1253 if ((scn_tgt = elf_getscn(elf, shdr_rel.sh_info)) == NULL || 1254 gelf_getshdr(scn_tgt, &shdr_tgt) == NULL || 1255 (data_tgt = elf_getdata(scn_tgt, NULL)) == NULL) 1256 goto err; 1257 1258 /* 1259 * We're looking for relocations to symbols matching this form: 1260 * 1261 * __dtrace[enabled]_<prov>___<probe> 1262 * 1263 * For the generated object, we need to record the location 1264 * identified by the relocation, and create a new relocation 1265 * in the generated object that will be resolved at link time 1266 * to the location of the function in which the probe is 1267 * embedded. In the target object, we change the matched symbol 1268 * so that it will be ignored at link time, and we modify the 1269 * target (text) section to replace the call instruction with 1270 * one or more nops. 1271 * 1272 * To avoid runtime overhead, the relocations added to the 1273 * generated object should be resolved at static link time. We 1274 * therefore create aliases for the functions that contain 1275 * probes. An alias is global (so that the relocation from the 1276 * generated object can be resolved), and hidden (so that its 1277 * address is known at static link time). Such aliases have this 1278 * form: 1279 * 1280 * $dtrace<key>.<function> 1281 * 1282 * We take a first pass through all the relocations to 1283 * populate our string table and count the number of extra 1284 * symbols we'll require. 1285 * 1286 * We also handle the case where the object has already been 1287 * processed, to support incremental rebuilds. Relocations 1288 * of interest are converted to type NONE, but all information 1289 * needed to reconstruct the output DOF is retained. 1290 */ 1291 strtab = dt_strtab_create(1); 1292 nsym = 0; 1293 isym = data_sym->d_size / symsize; 1294 istr = data_str->d_size; 1295 1296 for (i = 0; i < shdr_rel.sh_size / shdr_rel.sh_entsize; i++) { 1297 if (shdr_rel.sh_type == SHT_RELA) { 1298 if (gelf_getrela(data_rel, i, &rela) == NULL) 1299 continue; 1300 } else { 1301 GElf_Rel rel; 1302 if (gelf_getrel(data_rel, i, &rel) == NULL) 1303 continue; 1304 rela.r_offset = rel.r_offset; 1305 rela.r_info = rel.r_info; 1306 rela.r_addend = 0; 1307 } 1308 1309 if (gelf_getsym(data_sym, GELF_R_SYM(rela.r_info), 1310 &rsym) == NULL) { 1311 dt_strtab_destroy(strtab); 1312 goto err; 1313 } 1314 1315 s = (char *)data_str->d_buf + rsym.st_name; 1316 1317 if (strncmp(s, dt_prefix, sizeof (dt_prefix) - 1) != 0) 1318 continue; 1319 1320 if (dt_symtab_lookup(data_sym, 0, isym, rela.r_offset, 1321 shdr_rel.sh_info, &fsym, uses_funcdesc, 1322 elf) != 0) { 1323 dt_strtab_destroy(strtab); 1324 goto err; 1325 } 1326 1327 if (fsym.st_name > data_str->d_size) { 1328 dt_strtab_destroy(strtab); 1329 goto err; 1330 } 1331 1332 s = (char *)data_str->d_buf + fsym.st_name; 1333 1334 /* 1335 * If this symbol isn't of type function, we've really 1336 * driven off the rails or the object file is corrupt. 1337 */ 1338 if (GELF_ST_TYPE(fsym.st_info) != STT_FUNC) { 1339 dt_strtab_destroy(strtab); 1340 return (dt_link_error(dtp, elf, fd, bufs, 1341 "expected %s to be of type function", s)); 1342 } 1343 1344 /* 1345 * Aliases of weak symbols don't get a uniquifier. 1346 */ 1347 if (GELF_ST_BIND(fsym.st_info) == STB_WEAK) 1348 len = snprintf(NULL, 0, dt_weaksymfmt, 1349 dt_symprefix, s) + 1; 1350 else 1351 len = snprintf(NULL, 0, dt_symfmt, dt_symprefix, 1352 objkey, s) + 1; 1353 if ((p = dt_alloc(dtp, len)) == NULL) { 1354 dt_strtab_destroy(strtab); 1355 goto err; 1356 } 1357 (void) snprintf(p, len, dt_symfmt, dt_symprefix, 1358 objkey, s); 1359 1360 if (dt_strtab_index(strtab, p) == -1) { 1361 /* 1362 * Do not add new symbols if this object file 1363 * has already been processed. 1364 */ 1365 if (GELF_R_TYPE(rela.r_info) != DT_REL_NONE) 1366 nsym++; 1367 (void) dt_strtab_insert(strtab, p); 1368 } 1369 1370 dt_free(dtp, p); 1371 } 1372 1373 /* 1374 * If any new probes were found, allocate the additional space 1375 * for the symbol table and string table, copying the old data 1376 * into the new buffers, and marking the buffers as dirty. We 1377 * inject those newly allocated buffers into the libelf data 1378 * structures, but are still responsible for freeing them once 1379 * we're done with the elf handle. 1380 */ 1381 osym = isym; 1382 if (nsym > 0) { 1383 /* 1384 * The first byte of the string table is reserved for 1385 * the \0 entry. 1386 */ 1387 len = dt_strtab_size(strtab) - 1; 1388 1389 assert(len > 0); 1390 assert(dt_strtab_index(strtab, "") == 0); 1391 1392 dt_strtab_destroy(strtab); 1393 1394 if ((pair = dt_alloc(dtp, sizeof (*pair))) == NULL) 1395 goto err; 1396 1397 if ((pair->dlp_str = dt_alloc(dtp, data_str->d_size + 1398 len)) == NULL) { 1399 dt_free(dtp, pair); 1400 goto err; 1401 } 1402 1403 if ((pair->dlp_sym = dt_alloc(dtp, data_sym->d_size + 1404 nsym * symsize)) == NULL) { 1405 dt_free(dtp, pair->dlp_str); 1406 dt_free(dtp, pair); 1407 goto err; 1408 } 1409 1410 pair->dlp_next = bufs; 1411 bufs = pair; 1412 1413 bcopy(data_str->d_buf, pair->dlp_str, data_str->d_size); 1414 tmp = data_str->d_buf; 1415 data_str->d_buf = pair->dlp_str; 1416 pair->dlp_str = tmp; 1417 data_str->d_size += len; 1418 (void) elf_flagdata(data_str, ELF_C_SET, ELF_F_DIRTY); 1419 1420 shdr_str.sh_size += len; 1421 (void) gelf_update_shdr(scn_str, &shdr_str); 1422 1423 bcopy(data_sym->d_buf, pair->dlp_sym, data_sym->d_size); 1424 tmp = data_sym->d_buf; 1425 data_sym->d_buf = pair->dlp_sym; 1426 pair->dlp_sym = tmp; 1427 data_sym->d_size += nsym * symsize; 1428 (void) elf_flagdata(data_sym, ELF_C_SET, ELF_F_DIRTY); 1429 1430 shdr_sym.sh_size += nsym * symsize; 1431 (void) gelf_update_shdr(scn_sym, &shdr_sym); 1432 1433 nsym += isym; 1434 } else if (dt_strtab_empty(strtab)) { 1435 dt_strtab_destroy(strtab); 1436 continue; 1437 } 1438 1439 /* 1440 * Now that the tables have been allocated, perform the 1441 * modifications described above. 1442 */ 1443 for (i = 0; i < shdr_rel.sh_size / shdr_rel.sh_entsize; i++) { 1444 if (shdr_rel.sh_type == SHT_RELA) { 1445 if (gelf_getrela(data_rel, i, &rela) == NULL) 1446 continue; 1447 } else { 1448 GElf_Rel rel; 1449 if (gelf_getrel(data_rel, i, &rel) == NULL) 1450 continue; 1451 rela.r_offset = rel.r_offset; 1452 rela.r_info = rel.r_info; 1453 rela.r_addend = 0; 1454 } 1455 1456 ndx = GELF_R_SYM(rela.r_info); 1457 1458 if (gelf_getsym(data_sym, ndx, &rsym) == NULL || 1459 rsym.st_name > data_str->d_size) 1460 goto err; 1461 1462 s = (char *)data_str->d_buf + rsym.st_name; 1463 1464 if (strncmp(s, dt_prefix, sizeof (dt_prefix) - 1) != 0) 1465 continue; 1466 1467 s += sizeof (dt_prefix) - 1; 1468 1469 /* 1470 * Check to see if this is an 'is-enabled' check as 1471 * opposed to a normal probe. 1472 */ 1473 if (strncmp(s, dt_enabled, 1474 sizeof (dt_enabled) - 1) == 0) { 1475 s += sizeof (dt_enabled) - 1; 1476 eprobe = 1; 1477 *eprobesp = 1; 1478 dt_dprintf("is-enabled probe\n"); 1479 } else { 1480 eprobe = 0; 1481 dt_dprintf("normal probe\n"); 1482 } 1483 1484 if (*s++ != '_') 1485 goto err; 1486 1487 if ((p = strstr(s, "___")) == NULL || 1488 p - s >= sizeof (pname)) 1489 goto err; 1490 1491 bcopy(s, pname, p - s); 1492 pname[p - s] = '\0'; 1493 1494 if (dt_symtab_lookup(data_sym, osym, isym, 1495 rela.r_offset, shdr_rel.sh_info, &fsym, 1496 uses_funcdesc, elf) == 0) { 1497 if (fsym.st_name > data_str->d_size) 1498 goto err; 1499 1500 r = s = (char *) data_str->d_buf + fsym.st_name; 1501 assert(strstr(s, dt_symprefix) == s); 1502 s = strchr(s, '.') + 1; 1503 } else if (dt_symtab_lookup(data_sym, 0, osym, 1504 rela.r_offset, shdr_rel.sh_info, &fsym, 1505 uses_funcdesc, elf) == 0) { 1506 u_int bind; 1507 1508 bind = GELF_ST_BIND(fsym.st_info) == STB_WEAK ? 1509 STB_WEAK : STB_GLOBAL; 1510 s = (char *) data_str->d_buf + fsym.st_name; 1511 if (GELF_R_TYPE(rela.r_info) != DT_REL_NONE) { 1512 /* 1513 * Emit an alias for the symbol. It 1514 * needs to be non-preemptible so that 1515 * .SUNW_dof relocations may be resolved 1516 * at static link time. Aliases of weak 1517 * symbols are given a non-unique name 1518 * so that they may be merged by the 1519 * linker. 1520 */ 1521 dsym = fsym; 1522 dsym.st_name = istr; 1523 dsym.st_info = GELF_ST_INFO(bind, 1524 STT_FUNC); 1525 dsym.st_other = 1526 GELF_ST_VISIBILITY(STV_HIDDEN); 1527 (void) gelf_update_sym(data_sym, isym, 1528 &dsym); 1529 isym++; 1530 assert(isym <= nsym); 1531 1532 r = (char *) data_str->d_buf + istr; 1533 if (bind == STB_WEAK) { 1534 istr += sprintf(r, 1535 dt_weaksymfmt, dt_symprefix, 1536 s); 1537 } else { 1538 istr += sprintf(r, dt_symfmt, 1539 dt_symprefix, objkey, s); 1540 } 1541 istr++; 1542 } else { 1543 if (bind == STB_WEAK) { 1544 (void) asprintf(&r, 1545 dt_weaksymfmt, dt_symprefix, 1546 s); 1547 } else { 1548 (void) asprintf(&r, dt_symfmt, 1549 dt_symprefix, objkey, s); 1550 } 1551 } 1552 } else { 1553 goto err; 1554 } 1555 1556 if ((pvp = dt_provider_lookup(dtp, pname)) == NULL) { 1557 return (dt_link_error(dtp, elf, fd, bufs, 1558 "no such provider %s", pname)); 1559 } 1560 1561 if (strlcpy(probename, p + 3, sizeof (probename)) >= 1562 sizeof (probename)) 1563 return (dt_link_error(dtp, elf, fd, bufs, 1564 "invalid probe name %s", probename)); 1565 (void) strhyphenate(probename); 1566 if ((prp = dt_probe_lookup(pvp, probename)) == NULL) 1567 return (dt_link_error(dtp, elf, fd, bufs, 1568 "no such probe %s", probename)); 1569 1570 assert(fsym.st_value <= rela.r_offset); 1571 1572 off = rela.r_offset - fsym.st_value; 1573 if (dt_modtext(dtp, data_tgt->d_buf, eprobe, 1574 &rela, &off) != 0) 1575 goto err; 1576 1577 if (dt_probe_define(pvp, prp, s, r, off, eprobe) != 0) { 1578 return (dt_link_error(dtp, elf, fd, bufs, 1579 "failed to allocate space for probe")); 1580 } 1581 1582 /* 1583 * We are done with this relocation, but it must be 1584 * preserved in order to support incremental rebuilds. 1585 */ 1586 if (shdr_rel.sh_type == SHT_RELA) { 1587 rela.r_info = GELF_R_INFO( 1588 GELF_R_SYM(rela.r_info), DT_REL_NONE); 1589 (void) gelf_update_rela(data_rel, i, &rela); 1590 } else { 1591 GElf_Rel rel; 1592 rel.r_offset = rela.r_offset; 1593 rel.r_info = GELF_R_INFO( 1594 GELF_R_SYM(rela.r_info), DT_REL_NONE); 1595 (void) gelf_update_rel(data_rel, i, &rel); 1596 } 1597 1598 mod = 1; 1599 (void) elf_flagdata(data_tgt, ELF_C_SET, ELF_F_DIRTY); 1600 1601 /* 1602 * This symbol may already have been marked to 1603 * be ignored by another relocation referencing 1604 * the same symbol or if this object file has 1605 * already been processed by an earlier link 1606 * invocation. 1607 */ 1608 if (rsym.st_shndx != SHN_ABS) { 1609 rsym.st_shndx = SHN_ABS; 1610 (void) gelf_update_sym(data_sym, ndx, &rsym); 1611 } 1612 } 1613 } 1614 1615 if (mod && elf_update(elf, ELF_C_WRITE) == -1) 1616 goto err; 1617 1618 (void) elf_end(elf); 1619 (void) close(fd); 1620 1621 while ((pair = bufs) != NULL) { 1622 bufs = pair->dlp_next; 1623 dt_free(dtp, pair->dlp_str); 1624 dt_free(dtp, pair->dlp_sym); 1625 dt_free(dtp, pair); 1626 } 1627 1628 return (0); 1629 1630 err: 1631 return (dt_link_error(dtp, elf, fd, bufs, 1632 "an error was encountered while processing %s", obj)); 1633 } 1634 1635 int 1636 dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags, 1637 const char *file, int objc, char *const objv[]) 1638 { 1639 char tfile[PATH_MAX]; 1640 char drti[PATH_MAX]; 1641 dof_hdr_t *dof; 1642 int fd, status, i, cur; 1643 char *cmd, tmp; 1644 size_t len; 1645 int eprobes = 0, ret = 0; 1646 1647 /* 1648 * A NULL program indicates a special use in which we just link 1649 * together a bunch of object files specified in objv and then 1650 * unlink(2) those object files. 1651 */ 1652 if (pgp == NULL) { 1653 const char *fmt = "%s -o %s -r"; 1654 1655 len = snprintf(&tmp, 1, fmt, dtp->dt_ld_path, file) + 1; 1656 1657 for (i = 0; i < objc; i++) 1658 len += strlen(objv[i]) + 1; 1659 1660 cmd = alloca(len); 1661 1662 cur = snprintf(cmd, len, fmt, dtp->dt_ld_path, file); 1663 1664 for (i = 0; i < objc; i++) 1665 cur += snprintf(cmd + cur, len - cur, " %s", objv[i]); 1666 1667 if ((status = system(cmd)) == -1) { 1668 return (dt_link_error(dtp, NULL, -1, NULL, 1669 "failed to run %s: %s", dtp->dt_ld_path, 1670 strerror(errno))); 1671 } 1672 1673 if (WIFSIGNALED(status)) { 1674 return (dt_link_error(dtp, NULL, -1, NULL, 1675 "failed to link %s: %s failed due to signal %d", 1676 file, dtp->dt_ld_path, WTERMSIG(status))); 1677 } 1678 1679 if (WEXITSTATUS(status) != 0) { 1680 return (dt_link_error(dtp, NULL, -1, NULL, 1681 "failed to link %s: %s exited with status %d\n", 1682 file, dtp->dt_ld_path, WEXITSTATUS(status))); 1683 } 1684 1685 for (i = 0; i < objc; i++) { 1686 if (strcmp(objv[i], file) != 0) 1687 (void) unlink(objv[i]); 1688 } 1689 1690 return (0); 1691 } 1692 1693 for (i = 0; i < objc; i++) { 1694 if (process_obj(dtp, objv[i], &eprobes) != 0) 1695 return (-1); /* errno is set for us */ 1696 } 1697 1698 /* 1699 * If there are is-enabled probes then we need to force use of DOF 1700 * version 2. 1701 */ 1702 if (eprobes && pgp->dp_dofversion < DOF_VERSION_2) 1703 pgp->dp_dofversion = DOF_VERSION_2; 1704 1705 if ((dof = dtrace_dof_create(dtp, pgp, dflags)) == NULL) 1706 return (-1); /* errno is set for us */ 1707 1708 snprintf(tfile, sizeof(tfile), "%s.XXXXXX", file); 1709 if ((fd = mkostemp(tfile, O_CLOEXEC)) == -1) 1710 return (dt_link_error(dtp, NULL, -1, NULL, 1711 "failed to create temporary file %s: %s", 1712 tfile, strerror(errno))); 1713 1714 /* 1715 * If -xlinktype=DOF has been selected, just write out the DOF. 1716 * Otherwise proceed to the default of generating and linking ELF. 1717 */ 1718 switch (dtp->dt_linktype) { 1719 case DT_LTYP_DOF: 1720 if (dt_write(dtp, fd, dof, dof->dofh_filesz) < dof->dofh_filesz) 1721 ret = errno; 1722 1723 if (close(fd) != 0 && ret == 0) 1724 ret = errno; 1725 1726 if (ret != 0) { 1727 return (dt_link_error(dtp, NULL, -1, NULL, 1728 "failed to write %s: %s", file, strerror(ret))); 1729 } 1730 1731 return (0); 1732 1733 case DT_LTYP_ELF: 1734 break; /* fall through to the rest of dtrace_program_link() */ 1735 1736 default: 1737 return (dt_link_error(dtp, NULL, -1, NULL, 1738 "invalid link type %u\n", dtp->dt_linktype)); 1739 } 1740 1741 1742 if (dtp->dt_oflags & DTRACE_O_LP64) 1743 status = dump_elf64(dtp, dof, fd); 1744 else 1745 status = dump_elf32(dtp, dof, fd); 1746 1747 if (status != 0) 1748 return (dt_link_error(dtp, NULL, -1, NULL, 1749 "failed to write %s: %s", tfile, 1750 strerror(dtrace_errno(dtp)))); 1751 1752 if (!dtp->dt_lazyload) { 1753 const char *fmt = "%s -o %s -r %s %s"; 1754 dt_dirpath_t *dp = dt_list_next(&dtp->dt_lib_path); 1755 1756 (void) snprintf(drti, sizeof (drti), "%s/drti.o", dp->dir_path); 1757 1758 len = snprintf(&tmp, 1, fmt, dtp->dt_ld_path, file, tfile, 1759 drti) + 1; 1760 1761 cmd = alloca(len); 1762 1763 (void) snprintf(cmd, len, fmt, dtp->dt_ld_path, file, tfile, 1764 drti); 1765 if ((status = system(cmd)) == -1) { 1766 ret = dt_link_error(dtp, NULL, fd, NULL, 1767 "failed to run %s: %s", dtp->dt_ld_path, 1768 strerror(errno)); 1769 goto done; 1770 } 1771 1772 if (WIFSIGNALED(status)) { 1773 ret = dt_link_error(dtp, NULL, fd, NULL, 1774 "failed to link %s: %s failed due to signal %d", 1775 file, dtp->dt_ld_path, WTERMSIG(status)); 1776 goto done; 1777 } 1778 1779 if (WEXITSTATUS(status) != 0) { 1780 ret = dt_link_error(dtp, NULL, fd, NULL, 1781 "failed to link %s: %s exited with status %d\n", 1782 file, dtp->dt_ld_path, WEXITSTATUS(status)); 1783 goto done; 1784 } 1785 (void) close(fd); /* release temporary file */ 1786 1787 /* 1788 * Now that we've linked drti.o, reduce the global __SUNW_dof 1789 * symbol to a local symbol. This is needed to so that multiple 1790 * generated object files (for different providers, for 1791 * instance) can be linked together. This is accomplished using 1792 * the -Blocal flag with Sun's linker, but GNU ld doesn't appear 1793 * to have an equivalent option. 1794 */ 1795 asprintf(&cmd, "%s --localize-hidden %s", dtp->dt_objcopy_path, 1796 file); 1797 if ((status = system(cmd)) == -1) { 1798 ret = dt_link_error(dtp, NULL, -1, NULL, 1799 "failed to run %s: %s", dtp->dt_objcopy_path, 1800 strerror(errno)); 1801 free(cmd); 1802 goto done; 1803 } 1804 free(cmd); 1805 1806 if (WIFSIGNALED(status)) { 1807 ret = dt_link_error(dtp, NULL, -1, NULL, 1808 "failed to link %s: %s failed due to signal %d", 1809 file, dtp->dt_objcopy_path, WTERMSIG(status)); 1810 goto done; 1811 } 1812 1813 if (WEXITSTATUS(status) != 0) { 1814 ret = dt_link_error(dtp, NULL, -1, NULL, 1815 "failed to link %s: %s exited with status %d\n", 1816 file, dtp->dt_objcopy_path, WEXITSTATUS(status)); 1817 goto done; 1818 } 1819 } else { 1820 if (rename(tfile, file) != 0) { 1821 ret = dt_link_error(dtp, NULL, fd, NULL, 1822 "failed to rename %s to %s: %s", tfile, file, 1823 strerror(errno)); 1824 goto done; 1825 } 1826 (void) close(fd); 1827 } 1828 1829 done: 1830 dtrace_dof_destroy(dtp, dof); 1831 1832 if (!dtp->dt_lazyload) 1833 (void) unlink(tfile); 1834 return (ret); 1835 } 1836