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 2016 Mark Johnston. 26 */ 27 28 #define ELF_TARGET_ALL 29 #include <elf.h> 30 31 #include <sys/types.h> 32 #include <sys/sysmacros.h> 33 34 #include <unistd.h> 35 #include <strings.h> 36 #include <alloca.h> 37 #include <limits.h> 38 #include <stddef.h> 39 #include <stdlib.h> 40 #include <stdio.h> 41 #include <fcntl.h> 42 #include <errno.h> 43 #include <wait.h> 44 #include <assert.h> 45 #include <sys/ipc.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 #ifdef __sparc 72 ".rela.SUNW_dof"; /* 37 */ 73 #else 74 ".rel.SUNW_dof"; /* 37 */ 75 #endif 76 77 static const char DTRACE_SHSTRTAB64[] = "\0" 78 ".shstrtab\0" /* 1 */ 79 ".SUNW_dof\0" /* 11 */ 80 ".strtab\0" /* 21 */ 81 ".symtab\0" /* 29 */ 82 ".rela.SUNW_dof"; /* 37 */ 83 84 static const char DOFSTR[] = "__SUNW_dof"; 85 static const char DOFLAZYSTR[] = "___SUNW_dof"; 86 87 typedef struct dt_link_pair { 88 struct dt_link_pair *dlp_next; /* next pair in linked list */ 89 void *dlp_str; /* buffer for string table */ 90 void *dlp_sym; /* buffer for symbol table */ 91 } dt_link_pair_t; 92 93 typedef struct dof_elf32 { 94 uint32_t de_nrel; /* relocation count */ 95 #ifdef __sparc 96 Elf32_Rela *de_rel; /* array of relocations for sparc */ 97 #else 98 Elf32_Rel *de_rel; /* array of relocations for x86 */ 99 #endif 100 uint32_t de_nsym; /* symbol count */ 101 Elf32_Sym *de_sym; /* array of symbols */ 102 uint32_t de_strlen; /* size of of string table */ 103 char *de_strtab; /* string table */ 104 uint32_t de_global; /* index of the first global symbol */ 105 } dof_elf32_t; 106 107 static int prepare_elf32(dtrace_hdl_t * dtp,const dof_hdr_t * dof,dof_elf32_t * dep)108 prepare_elf32(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf32_t *dep) 109 { 110 dof_sec_t *dofs, *s; 111 dof_relohdr_t *dofrh; 112 dof_relodesc_t *dofr; 113 char *strtab; 114 int i, j, nrel; 115 size_t strtabsz = 1; 116 uint32_t count = 0; 117 size_t base; 118 Elf32_Sym *sym; 119 #ifdef __sparc 120 Elf32_Rela *rel; 121 #else 122 Elf32_Rel *rel; 123 #endif 124 125 /*LINTED*/ 126 dofs = (dof_sec_t *)((char *)dof + dof->dofh_secoff); 127 128 /* 129 * First compute the size of the string table and the number of 130 * relocations present in the DOF. 131 */ 132 for (i = 0; i < dof->dofh_secnum; i++) { 133 if (dofs[i].dofs_type != DOF_SECT_URELHDR) 134 continue; 135 136 /*LINTED*/ 137 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset); 138 139 s = &dofs[dofrh->dofr_strtab]; 140 strtab = (char *)dof + s->dofs_offset; 141 assert(strtab[0] == '\0'); 142 strtabsz += s->dofs_size - 1; 143 144 s = &dofs[dofrh->dofr_relsec]; 145 /*LINTED*/ 146 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset); 147 count += s->dofs_size / s->dofs_entsize; 148 } 149 150 dep->de_strlen = strtabsz; 151 dep->de_nrel = count; 152 dep->de_nsym = count + 1; /* the first symbol is always null */ 153 154 if (dtp->dt_lazyload) { 155 dep->de_strlen += sizeof (DOFLAZYSTR); 156 dep->de_nsym++; 157 } else { 158 dep->de_strlen += sizeof (DOFSTR); 159 dep->de_nsym++; 160 } 161 162 if ((dep->de_rel = calloc(dep->de_nrel, 163 sizeof (dep->de_rel[0]))) == NULL) { 164 return (dt_set_errno(dtp, EDT_NOMEM)); 165 } 166 167 if ((dep->de_sym = calloc(dep->de_nsym, sizeof (Elf32_Sym))) == NULL) { 168 free(dep->de_rel); 169 return (dt_set_errno(dtp, EDT_NOMEM)); 170 } 171 172 if ((dep->de_strtab = calloc(dep->de_strlen, 1)) == NULL) { 173 free(dep->de_rel); 174 free(dep->de_sym); 175 return (dt_set_errno(dtp, EDT_NOMEM)); 176 } 177 178 count = 0; 179 strtabsz = 1; 180 dep->de_strtab[0] = '\0'; 181 rel = dep->de_rel; 182 sym = dep->de_sym; 183 dep->de_global = 1; 184 185 /* 186 * The first symbol table entry must be zeroed and is always ignored. 187 */ 188 bzero(sym, sizeof (Elf32_Sym)); 189 sym++; 190 191 /* 192 * Take a second pass through the DOF sections filling in the 193 * memory we allocated. 194 */ 195 for (i = 0; i < dof->dofh_secnum; i++) { 196 if (dofs[i].dofs_type != DOF_SECT_URELHDR) 197 continue; 198 199 /*LINTED*/ 200 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset); 201 202 s = &dofs[dofrh->dofr_strtab]; 203 strtab = (char *)dof + s->dofs_offset; 204 bcopy(strtab + 1, dep->de_strtab + strtabsz, s->dofs_size); 205 base = strtabsz; 206 strtabsz += s->dofs_size - 1; 207 208 s = &dofs[dofrh->dofr_relsec]; 209 /*LINTED*/ 210 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset); 211 nrel = s->dofs_size / s->dofs_entsize; 212 213 s = &dofs[dofrh->dofr_tgtsec]; 214 215 for (j = 0; j < nrel; j++) { 216 #if defined(__i386) || defined(__amd64) 217 rel->r_offset = s->dofs_offset + 218 dofr[j].dofr_offset; 219 rel->r_info = ELF32_R_INFO(count + dep->de_global, 220 R_386_32); 221 #elif defined(__sparc) 222 /* 223 * Add 4 bytes to hit the low half of this 64-bit 224 * big-endian address. 225 */ 226 rel->r_offset = s->dofs_offset + 227 dofr[j].dofr_offset + 4; 228 rel->r_info = ELF32_R_INFO(count + dep->de_global, 229 R_SPARC_32); 230 #else 231 #error unknown ISA 232 #endif 233 234 sym->st_name = base + dofr[j].dofr_name - 1; 235 sym->st_value = 0; 236 sym->st_size = 0; 237 sym->st_info = ELF32_ST_INFO(STB_GLOBAL, STT_FUNC); 238 sym->st_other = 0; 239 sym->st_shndx = SHN_UNDEF; 240 241 rel++; 242 sym++; 243 count++; 244 } 245 } 246 247 /* 248 * Add a symbol for the DOF itself. We use a different symbol for 249 * lazily and actively loaded DOF to make them easy to distinguish. 250 */ 251 sym->st_name = strtabsz; 252 sym->st_value = 0; 253 sym->st_size = dof->dofh_filesz; 254 sym->st_info = ELF32_ST_INFO(STB_GLOBAL, STT_OBJECT); 255 sym->st_other = 0; 256 sym->st_shndx = ESHDR_DOF; 257 sym++; 258 259 if (dtp->dt_lazyload) { 260 bcopy(DOFLAZYSTR, dep->de_strtab + strtabsz, 261 sizeof (DOFLAZYSTR)); 262 strtabsz += sizeof (DOFLAZYSTR); 263 } else { 264 bcopy(DOFSTR, dep->de_strtab + strtabsz, sizeof (DOFSTR)); 265 strtabsz += sizeof (DOFSTR); 266 } 267 268 assert(count == dep->de_nrel); 269 assert(strtabsz == dep->de_strlen); 270 271 return (0); 272 } 273 274 275 typedef struct dof_elf64 { 276 uint32_t de_nrel; 277 Elf64_Rela *de_rel; 278 uint32_t de_nsym; 279 Elf64_Sym *de_sym; 280 281 uint32_t de_strlen; 282 char *de_strtab; 283 284 uint32_t de_global; 285 } dof_elf64_t; 286 287 static int prepare_elf64(dtrace_hdl_t * dtp,const dof_hdr_t * dof,dof_elf64_t * dep)288 prepare_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf64_t *dep) 289 { 290 dof_sec_t *dofs, *s; 291 dof_relohdr_t *dofrh; 292 dof_relodesc_t *dofr; 293 char *strtab; 294 int i, j, nrel; 295 size_t strtabsz = 1; 296 uint32_t count = 0; 297 size_t base; 298 Elf64_Sym *sym; 299 Elf64_Rela *rel; 300 301 /*LINTED*/ 302 dofs = (dof_sec_t *)((char *)dof + dof->dofh_secoff); 303 304 /* 305 * First compute the size of the string table and the number of 306 * relocations present in the DOF. 307 */ 308 for (i = 0; i < dof->dofh_secnum; i++) { 309 if (dofs[i].dofs_type != DOF_SECT_URELHDR) 310 continue; 311 312 /*LINTED*/ 313 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset); 314 315 s = &dofs[dofrh->dofr_strtab]; 316 strtab = (char *)dof + s->dofs_offset; 317 assert(strtab[0] == '\0'); 318 strtabsz += s->dofs_size - 1; 319 320 s = &dofs[dofrh->dofr_relsec]; 321 /*LINTED*/ 322 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset); 323 count += s->dofs_size / s->dofs_entsize; 324 } 325 326 dep->de_strlen = strtabsz; 327 dep->de_nrel = count; 328 dep->de_nsym = count + 1; /* the first symbol is always null */ 329 330 if (dtp->dt_lazyload) { 331 dep->de_strlen += sizeof (DOFLAZYSTR); 332 dep->de_nsym++; 333 } else { 334 dep->de_strlen += sizeof (DOFSTR); 335 dep->de_nsym++; 336 } 337 338 if ((dep->de_rel = calloc(dep->de_nrel, 339 sizeof (dep->de_rel[0]))) == NULL) { 340 return (dt_set_errno(dtp, EDT_NOMEM)); 341 } 342 343 if ((dep->de_sym = calloc(dep->de_nsym, sizeof (Elf64_Sym))) == NULL) { 344 free(dep->de_rel); 345 return (dt_set_errno(dtp, EDT_NOMEM)); 346 } 347 348 if ((dep->de_strtab = calloc(dep->de_strlen, 1)) == NULL) { 349 free(dep->de_rel); 350 free(dep->de_sym); 351 return (dt_set_errno(dtp, EDT_NOMEM)); 352 } 353 354 count = 0; 355 strtabsz = 1; 356 dep->de_strtab[0] = '\0'; 357 rel = dep->de_rel; 358 sym = dep->de_sym; 359 dep->de_global = 1; 360 361 /* 362 * The first symbol table entry must be zeroed and is always ignored. 363 */ 364 bzero(sym, sizeof (Elf64_Sym)); 365 sym++; 366 367 /* 368 * Take a second pass through the DOF sections filling in the 369 * memory we allocated. 370 */ 371 for (i = 0; i < dof->dofh_secnum; i++) { 372 if (dofs[i].dofs_type != DOF_SECT_URELHDR) 373 continue; 374 375 /*LINTED*/ 376 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset); 377 378 s = &dofs[dofrh->dofr_strtab]; 379 strtab = (char *)dof + s->dofs_offset; 380 bcopy(strtab + 1, dep->de_strtab + strtabsz, s->dofs_size); 381 base = strtabsz; 382 strtabsz += s->dofs_size - 1; 383 384 s = &dofs[dofrh->dofr_relsec]; 385 /*LINTED*/ 386 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset); 387 nrel = s->dofs_size / s->dofs_entsize; 388 389 s = &dofs[dofrh->dofr_tgtsec]; 390 391 for (j = 0; j < nrel; j++) { 392 #if defined(__i386) || defined(__amd64) 393 rel->r_offset = s->dofs_offset + 394 dofr[j].dofr_offset; 395 rel->r_info = ELF64_R_INFO(count + dep->de_global, 396 R_AMD64_64); 397 #elif defined(__sparc) 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_SPARC_64); 402 #else 403 #error unknown ISA 404 #endif 405 406 sym->st_name = base + dofr[j].dofr_name - 1; 407 sym->st_value = 0; 408 sym->st_size = 0; 409 sym->st_info = GELF_ST_INFO(STB_GLOBAL, STT_FUNC); 410 sym->st_other = 0; 411 sym->st_shndx = SHN_UNDEF; 412 413 rel++; 414 sym++; 415 count++; 416 } 417 } 418 419 /* 420 * Add a symbol for the DOF itself. We use a different symbol for 421 * lazily and actively loaded DOF to make them easy to distinguish. 422 */ 423 sym->st_name = strtabsz; 424 sym->st_value = 0; 425 sym->st_size = dof->dofh_filesz; 426 sym->st_info = GELF_ST_INFO(STB_GLOBAL, STT_OBJECT); 427 sym->st_other = 0; 428 sym->st_shndx = ESHDR_DOF; 429 sym++; 430 431 if (dtp->dt_lazyload) { 432 bcopy(DOFLAZYSTR, dep->de_strtab + strtabsz, 433 sizeof (DOFLAZYSTR)); 434 strtabsz += sizeof (DOFLAZYSTR); 435 } else { 436 bcopy(DOFSTR, dep->de_strtab + strtabsz, sizeof (DOFSTR)); 437 strtabsz += sizeof (DOFSTR); 438 } 439 440 assert(count == dep->de_nrel); 441 assert(strtabsz == dep->de_strlen); 442 443 return (0); 444 } 445 446 /* 447 * Write out an ELF32 file prologue consisting of a header, section headers, 448 * and a section header string table. The DOF data will follow this prologue 449 * and complete the contents of the given ELF file. 450 */ 451 static int dump_elf32(dtrace_hdl_t * dtp,const dof_hdr_t * dof,int fd)452 dump_elf32(dtrace_hdl_t *dtp, const dof_hdr_t *dof, int fd) 453 { 454 struct { 455 Elf32_Ehdr ehdr; 456 Elf32_Shdr shdr[ESHDR_NUM]; 457 } elf_file; 458 459 Elf32_Shdr *shp; 460 Elf32_Off off; 461 dof_elf32_t de; 462 int ret = 0; 463 uint_t nshdr; 464 465 if (prepare_elf32(dtp, dof, &de) != 0) 466 return (-1); /* errno is set for us */ 467 468 /* 469 * If there are no relocations, we only need enough sections for 470 * the shstrtab and the DOF. 471 */ 472 nshdr = de.de_nrel == 0 ? ESHDR_SYMTAB + 1 : ESHDR_NUM; 473 474 bzero(&elf_file, sizeof (elf_file)); 475 476 elf_file.ehdr.e_ident[EI_MAG0] = ELFMAG0; 477 elf_file.ehdr.e_ident[EI_MAG1] = ELFMAG1; 478 elf_file.ehdr.e_ident[EI_MAG2] = ELFMAG2; 479 elf_file.ehdr.e_ident[EI_MAG3] = ELFMAG3; 480 elf_file.ehdr.e_ident[EI_VERSION] = EV_CURRENT; 481 elf_file.ehdr.e_ident[EI_CLASS] = ELFCLASS32; 482 #if defined(_BIG_ENDIAN) 483 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2MSB; 484 #elif defined(_LITTLE_ENDIAN) 485 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2LSB; 486 #endif 487 elf_file.ehdr.e_type = ET_REL; 488 #if defined(__sparc) 489 elf_file.ehdr.e_machine = EM_SPARC; 490 #elif defined(__i386) || defined(__amd64) 491 elf_file.ehdr.e_machine = EM_386; 492 #endif 493 elf_file.ehdr.e_version = EV_CURRENT; 494 elf_file.ehdr.e_shoff = sizeof (Elf32_Ehdr); 495 elf_file.ehdr.e_ehsize = sizeof (Elf32_Ehdr); 496 elf_file.ehdr.e_phentsize = sizeof (Elf32_Phdr); 497 elf_file.ehdr.e_shentsize = sizeof (Elf32_Shdr); 498 elf_file.ehdr.e_shnum = nshdr; 499 elf_file.ehdr.e_shstrndx = ESHDR_SHSTRTAB; 500 off = sizeof (elf_file) + nshdr * sizeof (Elf32_Shdr); 501 502 shp = &elf_file.shdr[ESHDR_SHSTRTAB]; 503 shp->sh_name = 1; /* DTRACE_SHSTRTAB32[1] = ".shstrtab" */ 504 shp->sh_type = SHT_STRTAB; 505 shp->sh_offset = off; 506 shp->sh_size = sizeof (DTRACE_SHSTRTAB32); 507 shp->sh_addralign = sizeof (char); 508 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8); 509 510 shp = &elf_file.shdr[ESHDR_DOF]; 511 shp->sh_name = 11; /* DTRACE_SHSTRTAB32[11] = ".SUNW_dof" */ 512 shp->sh_flags = SHF_ALLOC; 513 shp->sh_type = SHT_SUNW_dof; 514 shp->sh_offset = off; 515 shp->sh_size = dof->dofh_filesz; 516 shp->sh_addralign = 8; 517 off = shp->sh_offset + shp->sh_size; 518 519 shp = &elf_file.shdr[ESHDR_STRTAB]; 520 shp->sh_name = 21; /* DTRACE_SHSTRTAB32[21] = ".strtab" */ 521 shp->sh_flags = SHF_ALLOC; 522 shp->sh_type = SHT_STRTAB; 523 shp->sh_offset = off; 524 shp->sh_size = de.de_strlen; 525 shp->sh_addralign = sizeof (char); 526 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 4); 527 528 shp = &elf_file.shdr[ESHDR_SYMTAB]; 529 shp->sh_name = 29; /* DTRACE_SHSTRTAB32[29] = ".symtab" */ 530 shp->sh_flags = SHF_ALLOC; 531 shp->sh_type = SHT_SYMTAB; 532 shp->sh_entsize = sizeof (Elf32_Sym); 533 shp->sh_link = ESHDR_STRTAB; 534 shp->sh_offset = off; 535 shp->sh_info = de.de_global; 536 shp->sh_size = de.de_nsym * sizeof (Elf32_Sym); 537 shp->sh_addralign = 4; 538 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 4); 539 540 if (de.de_nrel == 0) { 541 if (dt_write(dtp, fd, &elf_file, 542 sizeof (elf_file)) != sizeof (elf_file) || 543 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB32) || 544 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) || 545 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) || 546 PWRITE_SCN(ESHDR_DOF, dof)) { 547 ret = dt_set_errno(dtp, errno); 548 } 549 } else { 550 shp = &elf_file.shdr[ESHDR_REL]; 551 shp->sh_name = 37; /* DTRACE_SHSTRTAB32[37] = ".rel.SUNW_dof" */ 552 shp->sh_flags = SHF_ALLOC; 553 #ifdef __sparc 554 shp->sh_type = SHT_RELA; 555 #else 556 shp->sh_type = SHT_REL; 557 #endif 558 shp->sh_entsize = sizeof (de.de_rel[0]); 559 shp->sh_link = ESHDR_SYMTAB; 560 shp->sh_info = ESHDR_DOF; 561 shp->sh_offset = off; 562 shp->sh_size = de.de_nrel * sizeof (de.de_rel[0]); 563 shp->sh_addralign = 4; 564 565 if (dt_write(dtp, fd, &elf_file, 566 sizeof (elf_file)) != sizeof (elf_file) || 567 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB32) || 568 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) || 569 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) || 570 PWRITE_SCN(ESHDR_REL, de.de_rel) || 571 PWRITE_SCN(ESHDR_DOF, dof)) { 572 ret = dt_set_errno(dtp, errno); 573 } 574 } 575 576 free(de.de_strtab); 577 free(de.de_sym); 578 free(de.de_rel); 579 580 return (ret); 581 } 582 583 /* 584 * Write out an ELF64 file prologue consisting of a header, section headers, 585 * and a section header string table. The DOF data will follow this prologue 586 * and complete the contents of the given ELF file. 587 */ 588 static int dump_elf64(dtrace_hdl_t * dtp,const dof_hdr_t * dof,int fd)589 dump_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, int fd) 590 { 591 struct { 592 Elf64_Ehdr ehdr; 593 Elf64_Shdr shdr[ESHDR_NUM]; 594 } elf_file; 595 596 Elf64_Shdr *shp; 597 Elf64_Off off; 598 dof_elf64_t de; 599 int ret = 0; 600 uint_t nshdr; 601 602 if (prepare_elf64(dtp, dof, &de) != 0) 603 return (-1); /* errno is set for us */ 604 605 /* 606 * If there are no relocations, we only need enough sections for 607 * the shstrtab and the DOF. 608 */ 609 nshdr = de.de_nrel == 0 ? ESHDR_SYMTAB + 1 : ESHDR_NUM; 610 611 bzero(&elf_file, sizeof (elf_file)); 612 613 elf_file.ehdr.e_ident[EI_MAG0] = ELFMAG0; 614 elf_file.ehdr.e_ident[EI_MAG1] = ELFMAG1; 615 elf_file.ehdr.e_ident[EI_MAG2] = ELFMAG2; 616 elf_file.ehdr.e_ident[EI_MAG3] = ELFMAG3; 617 elf_file.ehdr.e_ident[EI_VERSION] = EV_CURRENT; 618 elf_file.ehdr.e_ident[EI_CLASS] = ELFCLASS64; 619 #if defined(_BIG_ENDIAN) 620 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2MSB; 621 #elif defined(_LITTLE_ENDIAN) 622 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2LSB; 623 #endif 624 elf_file.ehdr.e_type = ET_REL; 625 #if defined(__sparc) 626 elf_file.ehdr.e_machine = EM_SPARCV9; 627 #elif defined(__i386) || defined(__amd64) 628 elf_file.ehdr.e_machine = EM_AMD64; 629 #endif 630 elf_file.ehdr.e_version = EV_CURRENT; 631 elf_file.ehdr.e_shoff = sizeof (Elf64_Ehdr); 632 elf_file.ehdr.e_ehsize = sizeof (Elf64_Ehdr); 633 elf_file.ehdr.e_phentsize = sizeof (Elf64_Phdr); 634 elf_file.ehdr.e_shentsize = sizeof (Elf64_Shdr); 635 elf_file.ehdr.e_shnum = nshdr; 636 elf_file.ehdr.e_shstrndx = ESHDR_SHSTRTAB; 637 off = sizeof (elf_file) + nshdr * sizeof (Elf64_Shdr); 638 639 shp = &elf_file.shdr[ESHDR_SHSTRTAB]; 640 shp->sh_name = 1; /* DTRACE_SHSTRTAB64[1] = ".shstrtab" */ 641 shp->sh_type = SHT_STRTAB; 642 shp->sh_offset = off; 643 shp->sh_size = sizeof (DTRACE_SHSTRTAB64); 644 shp->sh_addralign = sizeof (char); 645 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8); 646 647 shp = &elf_file.shdr[ESHDR_DOF]; 648 shp->sh_name = 11; /* DTRACE_SHSTRTAB64[11] = ".SUNW_dof" */ 649 shp->sh_flags = SHF_ALLOC; 650 shp->sh_type = SHT_SUNW_dof; 651 shp->sh_offset = off; 652 shp->sh_size = dof->dofh_filesz; 653 shp->sh_addralign = 8; 654 off = shp->sh_offset + shp->sh_size; 655 656 shp = &elf_file.shdr[ESHDR_STRTAB]; 657 shp->sh_name = 21; /* DTRACE_SHSTRTAB64[21] = ".strtab" */ 658 shp->sh_flags = SHF_ALLOC; 659 shp->sh_type = SHT_STRTAB; 660 shp->sh_offset = off; 661 shp->sh_size = de.de_strlen; 662 shp->sh_addralign = sizeof (char); 663 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8); 664 665 shp = &elf_file.shdr[ESHDR_SYMTAB]; 666 shp->sh_name = 29; /* DTRACE_SHSTRTAB64[29] = ".symtab" */ 667 shp->sh_flags = SHF_ALLOC; 668 shp->sh_type = SHT_SYMTAB; 669 shp->sh_entsize = sizeof (Elf64_Sym); 670 shp->sh_link = ESHDR_STRTAB; 671 shp->sh_offset = off; 672 shp->sh_info = de.de_global; 673 shp->sh_size = de.de_nsym * sizeof (Elf64_Sym); 674 shp->sh_addralign = 8; 675 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8); 676 677 if (de.de_nrel == 0) { 678 if (dt_write(dtp, fd, &elf_file, 679 sizeof (elf_file)) != sizeof (elf_file) || 680 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB64) || 681 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) || 682 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) || 683 PWRITE_SCN(ESHDR_DOF, dof)) { 684 ret = dt_set_errno(dtp, errno); 685 } 686 } else { 687 shp = &elf_file.shdr[ESHDR_REL]; 688 shp->sh_name = 37; /* DTRACE_SHSTRTAB64[37] = ".rel.SUNW_dof" */ 689 shp->sh_flags = SHF_ALLOC; 690 shp->sh_type = SHT_RELA; 691 shp->sh_entsize = sizeof (de.de_rel[0]); 692 shp->sh_link = ESHDR_SYMTAB; 693 shp->sh_info = ESHDR_DOF; 694 shp->sh_offset = off; 695 shp->sh_size = de.de_nrel * sizeof (de.de_rel[0]); 696 shp->sh_addralign = 8; 697 698 if (dt_write(dtp, fd, &elf_file, 699 sizeof (elf_file)) != sizeof (elf_file) || 700 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB64) || 701 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) || 702 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) || 703 PWRITE_SCN(ESHDR_REL, de.de_rel) || 704 PWRITE_SCN(ESHDR_DOF, dof)) { 705 ret = dt_set_errno(dtp, errno); 706 } 707 } 708 709 free(de.de_strtab); 710 free(de.de_sym); 711 free(de.de_rel); 712 713 return (ret); 714 } 715 716 static int dt_symtab_lookup(Elf_Data * data_sym,int nsym,uintptr_t addr,uint_t shn,GElf_Sym * sym)717 dt_symtab_lookup(Elf_Data *data_sym, int nsym, uintptr_t addr, uint_t shn, 718 GElf_Sym *sym) 719 { 720 int i, ret = -1; 721 GElf_Sym s; 722 723 for (i = 0; i < nsym && gelf_getsym(data_sym, i, sym) != NULL; i++) { 724 if (GELF_ST_TYPE(sym->st_info) == STT_FUNC && 725 shn == sym->st_shndx && 726 sym->st_value <= addr && 727 addr < sym->st_value + sym->st_size) { 728 if (GELF_ST_BIND(sym->st_info) == STB_GLOBAL) 729 return (0); 730 731 ret = 0; 732 s = *sym; 733 } 734 } 735 736 if (ret == 0) 737 *sym = s; 738 return (ret); 739 } 740 741 #if defined(__sparc) 742 743 #define DT_OP_RET 0x81c7e008 744 #define DT_OP_NOP 0x01000000 745 #define DT_OP_CALL 0x40000000 746 #define DT_OP_CLR_O0 0x90102000 747 748 #define DT_IS_MOV_O7(inst) (((inst) & 0xffffe000) == 0x9e100000) 749 #define DT_IS_RESTORE(inst) (((inst) & 0xc1f80000) == 0x81e80000) 750 #define DT_IS_RETL(inst) (((inst) & 0xfff83fff) == 0x81c02008) 751 752 #define DT_RS2(inst) ((inst) & 0x1f) 753 #define DT_MAKE_RETL(reg) (0x81c02008 | ((reg) << 14)) 754 755 /*ARGSUSED*/ 756 static int dt_modtext(dtrace_hdl_t * dtp,char * p,int isenabled,GElf_Rela * rela,uint32_t * off)757 dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela, 758 uint32_t *off) 759 { 760 uint32_t *ip; 761 762 if ((rela->r_offset & (sizeof (uint32_t) - 1)) != 0) 763 return (-1); 764 765 /*LINTED*/ 766 ip = (uint32_t *)(p + rela->r_offset); 767 768 /* 769 * We only know about some specific relocation types. 770 */ 771 if (GELF_R_TYPE(rela->r_info) != R_SPARC_WDISP30 && 772 GELF_R_TYPE(rela->r_info) != R_SPARC_WPLT30) 773 return (-1); 774 775 /* 776 * We may have already processed this object file in an earlier linker 777 * invocation. Check to see if the present instruction sequence matches 778 * the one we would install below. 779 */ 780 if (isenabled) { 781 if (ip[0] == DT_OP_NOP) { 782 (*off) += sizeof (ip[0]); 783 return (0); 784 } 785 } else { 786 if (DT_IS_RESTORE(ip[1])) { 787 if (ip[0] == DT_OP_RET) { 788 (*off) += sizeof (ip[0]); 789 return (0); 790 } 791 } else if (DT_IS_MOV_O7(ip[1])) { 792 if (DT_IS_RETL(ip[0])) 793 return (0); 794 } else { 795 if (ip[0] == DT_OP_NOP) { 796 (*off) += sizeof (ip[0]); 797 return (0); 798 } 799 } 800 } 801 802 /* 803 * We only expect call instructions with a displacement of 0. 804 */ 805 if (ip[0] != DT_OP_CALL) { 806 dt_dprintf("found %x instead of a call instruction at %llx\n", 807 ip[0], (u_longlong_t)rela->r_offset); 808 return (-1); 809 } 810 811 if (isenabled) { 812 /* 813 * It would necessarily indicate incorrect usage if an is- 814 * enabled probe were tail-called so flag that as an error. 815 * It's also potentially (very) tricky to handle gracefully, 816 * but could be done if this were a desired use scenario. 817 */ 818 if (DT_IS_RESTORE(ip[1]) || DT_IS_MOV_O7(ip[1])) { 819 dt_dprintf("tail call to is-enabled probe at %llx\n", 820 (u_longlong_t)rela->r_offset); 821 return (-1); 822 } 823 824 825 /* 826 * On SPARC, we take advantage of the fact that the first 827 * argument shares the same register as for the return value. 828 * The macro handles the work of zeroing that register so we 829 * don't need to do anything special here. We instrument the 830 * instruction in the delay slot as we'll need to modify the 831 * return register after that instruction has been emulated. 832 */ 833 ip[0] = DT_OP_NOP; 834 (*off) += sizeof (ip[0]); 835 } else { 836 /* 837 * If the call is followed by a restore, it's a tail call so 838 * change the call to a ret. If the call if followed by a mov 839 * of a register into %o7, it's a tail call in leaf context 840 * so change the call to a retl-like instruction that returns 841 * to that register value + 8 (rather than the typical %o7 + 842 * 8); the delay slot instruction is left, but should have no 843 * effect. Otherwise we change the call to be a nop. We 844 * identify the subsequent instruction as the probe point in 845 * all but the leaf tail-call case to ensure that arguments to 846 * the probe are complete and consistent. An astute, though 847 * largely hypothetical, observer would note that there is the 848 * possibility of a false-positive probe firing if the function 849 * contained a branch to the instruction in the delay slot of 850 * the call. Fixing this would require significant in-kernel 851 * modifications, and isn't worth doing until we see it in the 852 * wild. 853 */ 854 if (DT_IS_RESTORE(ip[1])) { 855 ip[0] = DT_OP_RET; 856 (*off) += sizeof (ip[0]); 857 } else if (DT_IS_MOV_O7(ip[1])) { 858 ip[0] = DT_MAKE_RETL(DT_RS2(ip[1])); 859 } else { 860 ip[0] = DT_OP_NOP; 861 (*off) += sizeof (ip[0]); 862 } 863 } 864 865 return (0); 866 } 867 868 #elif defined(__i386) || defined(__amd64) 869 870 #define DT_OP_NOP 0x90 871 #define DT_OP_RET 0xc3 872 #define DT_OP_CALL 0xe8 873 #define DT_OP_JMP32 0xe9 874 #define DT_OP_REX_RAX 0x48 875 #define DT_OP_XOR_EAX_0 0x33 876 #define DT_OP_XOR_EAX_1 0xc0 877 878 static int dt_modtext(dtrace_hdl_t * dtp,char * p,int isenabled,GElf_Rela * rela,uint32_t * off)879 dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela, 880 uint32_t *off) 881 { 882 uint8_t *ip = (uint8_t *)(p + rela->r_offset - 1); 883 uint8_t ret; 884 885 /* 886 * On x86, the first byte of the instruction is the call opcode and 887 * the next four bytes are the 32-bit address; the relocation is for 888 * the address operand. We back up the offset to the first byte of 889 * the instruction. For is-enabled probes, we later advance the offset 890 * so that it hits the first nop in the instruction sequence. 891 */ 892 (*off) -= 1; 893 894 /* 895 * We only know about some specific relocation types. Luckily 896 * these types have the same values on both 32-bit and 64-bit 897 * x86 architectures. 898 */ 899 if (GELF_R_TYPE(rela->r_info) != R_386_PC32 && 900 GELF_R_TYPE(rela->r_info) != R_386_PLT32) 901 return (-1); 902 903 /* 904 * We may have already processed this object file in an earlier linker 905 * invocation. Check to see if the present instruction sequence matches 906 * the one we would install. For is-enabled probes, we advance the 907 * offset to the first nop instruction in the sequence to match the 908 * text modification code below. 909 */ 910 if (!isenabled) { 911 if ((ip[0] == DT_OP_NOP || ip[0] == DT_OP_RET) && 912 ip[1] == DT_OP_NOP && ip[2] == DT_OP_NOP && 913 ip[3] == DT_OP_NOP && ip[4] == DT_OP_NOP) 914 return (0); 915 } else if (dtp->dt_oflags & DTRACE_O_LP64) { 916 if (ip[0] == DT_OP_REX_RAX && 917 ip[1] == DT_OP_XOR_EAX_0 && ip[2] == DT_OP_XOR_EAX_1 && 918 (ip[3] == DT_OP_NOP || ip[3] == DT_OP_RET) && 919 ip[4] == DT_OP_NOP) { 920 (*off) += 3; 921 return (0); 922 } 923 } else { 924 if (ip[0] == DT_OP_XOR_EAX_0 && ip[1] == DT_OP_XOR_EAX_1 && 925 (ip[2] == DT_OP_NOP || ip[2] == DT_OP_RET) && 926 ip[3] == DT_OP_NOP && ip[4] == DT_OP_NOP) { 927 (*off) += 2; 928 return (0); 929 } 930 } 931 932 /* 933 * We expect either a call instrution with a 32-bit displacement or a 934 * jmp instruction with a 32-bit displacement acting as a tail-call. 935 */ 936 if (ip[0] != DT_OP_CALL && ip[0] != DT_OP_JMP32) { 937 dt_dprintf("found %x instead of a call or jmp instruction at " 938 "%llx\n", ip[0], (u_longlong_t)rela->r_offset); 939 return (-1); 940 } 941 942 ret = (ip[0] == DT_OP_JMP32) ? DT_OP_RET : DT_OP_NOP; 943 944 /* 945 * Establish the instruction sequence -- all nops for probes, and an 946 * instruction to clear the return value register (%eax/%rax) followed 947 * by nops for is-enabled probes. For is-enabled probes, we advance 948 * the offset to the first nop. This isn't stricly necessary but makes 949 * for more readable disassembly when the probe is enabled. 950 */ 951 if (!isenabled) { 952 ip[0] = ret; 953 ip[1] = DT_OP_NOP; 954 ip[2] = DT_OP_NOP; 955 ip[3] = DT_OP_NOP; 956 ip[4] = DT_OP_NOP; 957 } else if (dtp->dt_oflags & DTRACE_O_LP64) { 958 ip[0] = DT_OP_REX_RAX; 959 ip[1] = DT_OP_XOR_EAX_0; 960 ip[2] = DT_OP_XOR_EAX_1; 961 ip[3] = ret; 962 ip[4] = DT_OP_NOP; 963 (*off) += 3; 964 } else { 965 ip[0] = DT_OP_XOR_EAX_0; 966 ip[1] = DT_OP_XOR_EAX_1; 967 ip[2] = ret; 968 ip[3] = DT_OP_NOP; 969 ip[4] = DT_OP_NOP; 970 (*off) += 2; 971 } 972 973 return (0); 974 } 975 976 #else 977 #error unknown ISA 978 #endif 979 980 /*PRINTFLIKE5*/ 981 static int dt_link_error(dtrace_hdl_t * dtp,Elf * elf,int fd,dt_link_pair_t * bufs,const char * format,...)982 dt_link_error(dtrace_hdl_t *dtp, Elf *elf, int fd, dt_link_pair_t *bufs, 983 const char *format, ...) 984 { 985 va_list ap; 986 dt_link_pair_t *pair; 987 988 va_start(ap, format); 989 dt_set_errmsg(dtp, NULL, NULL, NULL, 0, format, ap); 990 va_end(ap); 991 992 if (elf != NULL) 993 (void) elf_end(elf); 994 995 if (fd >= 0) 996 (void) close(fd); 997 998 while ((pair = bufs) != NULL) { 999 bufs = pair->dlp_next; 1000 dt_free(dtp, pair->dlp_str); 1001 dt_free(dtp, pair->dlp_sym); 1002 dt_free(dtp, pair); 1003 } 1004 1005 return (dt_set_errno(dtp, EDT_COMPILER)); 1006 } 1007 1008 static int process_obj(dtrace_hdl_t * dtp,const char * obj,int * eprobesp)1009 process_obj(dtrace_hdl_t *dtp, const char *obj, int *eprobesp) 1010 { 1011 static const char dt_prefix[] = "__dtrace"; 1012 static const char dt_enabled[] = "enabled"; 1013 static const char dt_symprefix[] = "$dtrace"; 1014 static const char dt_symfmt[] = "%s%d.%s"; 1015 char probename[DTRACE_NAMELEN]; 1016 int fd, i, ndx, eprobe, mod = 0; 1017 Elf *elf = NULL; 1018 GElf_Ehdr ehdr; 1019 Elf_Scn *scn_rel, *scn_sym, *scn_str, *scn_tgt; 1020 Elf_Data *data_rel, *data_sym, *data_str, *data_tgt; 1021 GElf_Shdr shdr_rel, shdr_sym, shdr_str, shdr_tgt; 1022 GElf_Sym rsym, fsym, dsym; 1023 GElf_Rela rela; 1024 char *s, *p, *r; 1025 char pname[DTRACE_PROVNAMELEN]; 1026 dt_provider_t *pvp; 1027 dt_probe_t *prp; 1028 uint32_t off, eclass, emachine1, emachine2; 1029 size_t symsize, nsym, isym, istr, len; 1030 key_t objkey; 1031 dt_link_pair_t *pair, *bufs = NULL; 1032 dt_strtab_t *strtab; 1033 1034 if ((fd = open64(obj, O_RDWR)) == -1) { 1035 return (dt_link_error(dtp, elf, fd, bufs, 1036 "failed to open %s: %s", obj, strerror(errno))); 1037 } 1038 1039 if ((elf = elf_begin(fd, ELF_C_RDWR, NULL)) == NULL) { 1040 return (dt_link_error(dtp, elf, fd, bufs, 1041 "failed to process %s: %s", obj, elf_errmsg(elf_errno()))); 1042 } 1043 1044 switch (elf_kind(elf)) { 1045 case ELF_K_ELF: 1046 break; 1047 case ELF_K_AR: 1048 return (dt_link_error(dtp, elf, fd, bufs, "archives are not " 1049 "permitted; use the contents of the archive instead: %s", 1050 obj)); 1051 default: 1052 return (dt_link_error(dtp, elf, fd, bufs, 1053 "invalid file type: %s", obj)); 1054 } 1055 1056 if (gelf_getehdr(elf, &ehdr) == NULL) { 1057 return (dt_link_error(dtp, elf, fd, bufs, "corrupt file: %s", 1058 obj)); 1059 } 1060 1061 if (dtp->dt_oflags & DTRACE_O_LP64) { 1062 eclass = ELFCLASS64; 1063 #if defined(__sparc) 1064 emachine1 = emachine2 = EM_SPARCV9; 1065 #elif defined(__i386) || defined(__amd64) 1066 emachine1 = emachine2 = EM_AMD64; 1067 #endif 1068 symsize = sizeof (Elf64_Sym); 1069 } else { 1070 eclass = ELFCLASS32; 1071 #if defined(__sparc) 1072 emachine1 = EM_SPARC; 1073 emachine2 = EM_SPARC32PLUS; 1074 #elif defined(__i386) || defined(__amd64) 1075 emachine1 = emachine2 = EM_386; 1076 #endif 1077 symsize = sizeof (Elf32_Sym); 1078 } 1079 1080 if (ehdr.e_ident[EI_CLASS] != eclass) { 1081 return (dt_link_error(dtp, elf, fd, bufs, 1082 "incorrect ELF class for object file: %s", obj)); 1083 } 1084 1085 if (ehdr.e_machine != emachine1 && ehdr.e_machine != emachine2) { 1086 return (dt_link_error(dtp, elf, fd, bufs, 1087 "incorrect ELF machine type for object file: %s", obj)); 1088 } 1089 1090 /* 1091 * We use this token as a relatively unique handle for this file on the 1092 * system in order to disambiguate potential conflicts between files of 1093 * the same name which contain identially named local symbols. 1094 */ 1095 if ((objkey = ftok(obj, 0)) == (key_t)-1) { 1096 return (dt_link_error(dtp, elf, fd, bufs, 1097 "failed to generate unique key for object file: %s", obj)); 1098 } 1099 1100 scn_rel = NULL; 1101 while ((scn_rel = elf_nextscn(elf, scn_rel)) != NULL) { 1102 if (gelf_getshdr(scn_rel, &shdr_rel) == NULL) 1103 goto err; 1104 1105 /* 1106 * Skip any non-relocation sections. 1107 */ 1108 if (shdr_rel.sh_type != SHT_RELA && shdr_rel.sh_type != SHT_REL) 1109 continue; 1110 1111 if ((data_rel = elf_getdata(scn_rel, NULL)) == NULL) 1112 goto err; 1113 1114 /* 1115 * Grab the section, section header and section data for the 1116 * symbol table that this relocation section references. 1117 */ 1118 if ((scn_sym = elf_getscn(elf, shdr_rel.sh_link)) == NULL || 1119 gelf_getshdr(scn_sym, &shdr_sym) == NULL || 1120 (data_sym = elf_getdata(scn_sym, NULL)) == NULL) 1121 goto err; 1122 1123 /* 1124 * Ditto for that symbol table's string table. 1125 */ 1126 if ((scn_str = elf_getscn(elf, shdr_sym.sh_link)) == NULL || 1127 gelf_getshdr(scn_str, &shdr_str) == NULL || 1128 (data_str = elf_getdata(scn_str, NULL)) == NULL) 1129 goto err; 1130 1131 /* 1132 * Grab the section, section header and section data for the 1133 * target section for the relocations. For the relocations 1134 * we're looking for -- this will typically be the text of the 1135 * object file. 1136 */ 1137 if ((scn_tgt = elf_getscn(elf, shdr_rel.sh_info)) == NULL || 1138 gelf_getshdr(scn_tgt, &shdr_tgt) == NULL || 1139 (data_tgt = elf_getdata(scn_tgt, NULL)) == NULL) 1140 goto err; 1141 1142 /* 1143 * We're looking for relocations to symbols matching this form: 1144 * 1145 * __dtrace[enabled]_<prov>___<probe> 1146 * 1147 * For the generated object, we need to record the location 1148 * identified by the relocation, and create a new relocation 1149 * in the generated object that will be resolved at link time 1150 * to the location of the function in which the probe is 1151 * embedded. In the target object, we change the matched symbol 1152 * so that it will be ignored at link time, and we modify the 1153 * target (text) section to replace the call instruction with 1154 * one or more nops. 1155 * 1156 * If the function containing the probe is locally scoped 1157 * (static), we create an alias used by the relocation in the 1158 * generated object. The alias, a new symbol, will be global 1159 * (so that the relocation from the generated object can be 1160 * resolved), and hidden (so that it is converted to a local 1161 * symbol at link time). Such aliases have this form: 1162 * 1163 * $dtrace<key>.<function> 1164 * 1165 * We take a first pass through all the relocations to 1166 * populate our string table and count the number of extra 1167 * symbols we'll require. 1168 */ 1169 strtab = dt_strtab_create(1); 1170 nsym = 0; 1171 isym = data_sym->d_size / symsize; 1172 istr = data_str->d_size; 1173 1174 for (i = 0; i < shdr_rel.sh_size / shdr_rel.sh_entsize; i++) { 1175 1176 if (shdr_rel.sh_type == SHT_RELA) { 1177 if (gelf_getrela(data_rel, i, &rela) == NULL) 1178 continue; 1179 } else { 1180 GElf_Rel rel; 1181 if (gelf_getrel(data_rel, i, &rel) == NULL) 1182 continue; 1183 rela.r_offset = rel.r_offset; 1184 rela.r_info = rel.r_info; 1185 rela.r_addend = 0; 1186 } 1187 1188 if (gelf_getsym(data_sym, GELF_R_SYM(rela.r_info), 1189 &rsym) == NULL) { 1190 dt_strtab_destroy(strtab); 1191 goto err; 1192 } 1193 1194 s = (char *)data_str->d_buf + rsym.st_name; 1195 1196 if (strncmp(s, dt_prefix, sizeof (dt_prefix) - 1) != 0) 1197 continue; 1198 1199 if (dt_symtab_lookup(data_sym, isym, rela.r_offset, 1200 shdr_rel.sh_info, &fsym) != 0) { 1201 dt_strtab_destroy(strtab); 1202 goto err; 1203 } 1204 1205 if (GELF_ST_BIND(fsym.st_info) != STB_LOCAL) 1206 continue; 1207 1208 if (fsym.st_name > data_str->d_size) { 1209 dt_strtab_destroy(strtab); 1210 goto err; 1211 } 1212 1213 s = (char *)data_str->d_buf + fsym.st_name; 1214 1215 /* 1216 * If this symbol isn't of type function, we've really 1217 * driven off the rails or the object file is corrupt. 1218 */ 1219 if (GELF_ST_TYPE(fsym.st_info) != STT_FUNC) { 1220 dt_strtab_destroy(strtab); 1221 return (dt_link_error(dtp, elf, fd, bufs, 1222 "expected %s to be of type function", s)); 1223 } 1224 1225 len = snprintf(NULL, 0, dt_symfmt, dt_symprefix, 1226 objkey, s) + 1; 1227 if ((p = dt_alloc(dtp, len)) == NULL) { 1228 dt_strtab_destroy(strtab); 1229 goto err; 1230 } 1231 (void) snprintf(p, len, dt_symfmt, dt_symprefix, 1232 objkey, s); 1233 1234 if (dt_strtab_index(strtab, p) == -1) { 1235 nsym++; 1236 (void) dt_strtab_insert(strtab, p); 1237 } 1238 1239 dt_free(dtp, p); 1240 } 1241 1242 /* 1243 * If needed, allocate the additional space for the symbol 1244 * table and string table copying the old data into the new 1245 * buffers, and marking the buffers as dirty. We inject those 1246 * newly allocated buffers into the libelf data structures, but 1247 * are still responsible for freeing them once we're done with 1248 * the elf handle. 1249 */ 1250 if (nsym > 0) { 1251 /* 1252 * The first byte of the string table is reserved for 1253 * the \0 entry. 1254 */ 1255 len = dt_strtab_size(strtab) - 1; 1256 1257 assert(len > 0); 1258 assert(dt_strtab_index(strtab, "") == 0); 1259 1260 dt_strtab_destroy(strtab); 1261 1262 if ((pair = dt_alloc(dtp, sizeof (*pair))) == NULL) 1263 goto err; 1264 1265 if ((pair->dlp_str = dt_alloc(dtp, data_str->d_size + 1266 len)) == NULL) { 1267 dt_free(dtp, pair); 1268 goto err; 1269 } 1270 1271 if ((pair->dlp_sym = dt_alloc(dtp, data_sym->d_size + 1272 nsym * symsize)) == NULL) { 1273 dt_free(dtp, pair->dlp_str); 1274 dt_free(dtp, pair); 1275 goto err; 1276 } 1277 1278 pair->dlp_next = bufs; 1279 bufs = pair; 1280 1281 bcopy(data_str->d_buf, pair->dlp_str, data_str->d_size); 1282 data_str->d_buf = pair->dlp_str; 1283 data_str->d_size += len; 1284 (void) elf_flagdata(data_str, ELF_C_SET, ELF_F_DIRTY); 1285 1286 shdr_str.sh_size += len; 1287 (void) gelf_update_shdr(scn_str, &shdr_str); 1288 1289 bcopy(data_sym->d_buf, pair->dlp_sym, data_sym->d_size); 1290 data_sym->d_buf = pair->dlp_sym; 1291 data_sym->d_size += nsym * symsize; 1292 (void) elf_flagdata(data_sym, ELF_C_SET, ELF_F_DIRTY); 1293 1294 shdr_sym.sh_size += nsym * symsize; 1295 (void) gelf_update_shdr(scn_sym, &shdr_sym); 1296 1297 nsym += isym; 1298 } else { 1299 dt_strtab_destroy(strtab); 1300 } 1301 1302 /* 1303 * Now that the tables have been allocated, perform the 1304 * modifications described above. 1305 */ 1306 for (i = 0; i < shdr_rel.sh_size / shdr_rel.sh_entsize; i++) { 1307 1308 if (shdr_rel.sh_type == SHT_RELA) { 1309 if (gelf_getrela(data_rel, i, &rela) == NULL) 1310 continue; 1311 } else { 1312 GElf_Rel rel; 1313 if (gelf_getrel(data_rel, i, &rel) == NULL) 1314 continue; 1315 rela.r_offset = rel.r_offset; 1316 rela.r_info = rel.r_info; 1317 rela.r_addend = 0; 1318 } 1319 1320 ndx = GELF_R_SYM(rela.r_info); 1321 1322 if (gelf_getsym(data_sym, ndx, &rsym) == NULL || 1323 rsym.st_name > data_str->d_size) 1324 goto err; 1325 1326 s = (char *)data_str->d_buf + rsym.st_name; 1327 1328 if (strncmp(s, dt_prefix, sizeof (dt_prefix) - 1) != 0) 1329 continue; 1330 1331 s += sizeof (dt_prefix) - 1; 1332 1333 /* 1334 * Check to see if this is an 'is-enabled' check as 1335 * opposed to a normal probe. 1336 */ 1337 if (strncmp(s, dt_enabled, 1338 sizeof (dt_enabled) - 1) == 0) { 1339 s += sizeof (dt_enabled) - 1; 1340 eprobe = 1; 1341 *eprobesp = 1; 1342 dt_dprintf("is-enabled probe\n"); 1343 } else { 1344 eprobe = 0; 1345 dt_dprintf("normal probe\n"); 1346 } 1347 1348 if (*s++ != '_') 1349 goto err; 1350 1351 if ((p = strstr(s, "___")) == NULL || 1352 p - s >= sizeof (pname)) 1353 goto err; 1354 1355 bcopy(s, pname, p - s); 1356 pname[p - s] = '\0'; 1357 1358 if (dt_symtab_lookup(data_sym, isym, rela.r_offset, 1359 shdr_rel.sh_info, &fsym) != 0) 1360 goto err; 1361 1362 if (fsym.st_name > data_str->d_size) 1363 goto err; 1364 1365 assert(GELF_ST_TYPE(fsym.st_info) == STT_FUNC); 1366 1367 /* 1368 * If a NULL relocation name is passed to 1369 * dt_probe_define(), the function name is used for the 1370 * relocation. The relocation needs to use a mangled 1371 * name if the symbol is locally scoped; the function 1372 * name may need to change if we've found the global 1373 * alias for the locally scoped symbol (we prefer 1374 * global symbols to locals in dt_symtab_lookup()). 1375 */ 1376 s = (char *)data_str->d_buf + fsym.st_name; 1377 r = NULL; 1378 1379 if (GELF_ST_BIND(fsym.st_info) == STB_LOCAL) { 1380 dsym = fsym; 1381 dsym.st_name = istr; 1382 dsym.st_info = GELF_ST_INFO(STB_GLOBAL, 1383 STT_FUNC); 1384 dsym.st_other = 1385 ELF64_ST_VISIBILITY(STV_ELIMINATE); 1386 (void) gelf_update_sym(data_sym, isym, &dsym); 1387 1388 r = (char *)data_str->d_buf + istr; 1389 istr += 1 + sprintf(r, dt_symfmt, 1390 dt_symprefix, objkey, s); 1391 isym++; 1392 assert(isym <= nsym); 1393 1394 } else if (strncmp(s, dt_symprefix, 1395 strlen(dt_symprefix)) == 0) { 1396 r = s; 1397 if ((s = strchr(s, '.')) == NULL) 1398 goto err; 1399 s++; 1400 } 1401 1402 if ((pvp = dt_provider_lookup(dtp, pname)) == NULL) { 1403 return (dt_link_error(dtp, elf, fd, bufs, 1404 "no such provider %s", pname)); 1405 } 1406 1407 /* strlen("___") */ 1408 if (strlcpy(probename, p + 3, sizeof (probename)) >= 1409 sizeof (probename)) 1410 return (dt_link_error(dtp, elf, fd, bufs, 1411 "probe name too long %s", probename)); 1412 1413 (void) strhyphenate(probename); 1414 1415 if ((prp = dt_probe_lookup(pvp, probename)) == NULL) { 1416 return (dt_link_error(dtp, elf, fd, bufs, 1417 "no such probe %s", probename)); 1418 } 1419 1420 assert(fsym.st_value <= rela.r_offset); 1421 1422 off = rela.r_offset - fsym.st_value; 1423 if (dt_modtext(dtp, data_tgt->d_buf, eprobe, 1424 &rela, &off) != 0) { 1425 goto err; 1426 } 1427 1428 if (dt_probe_define(pvp, prp, s, r, off, eprobe) != 0) { 1429 return (dt_link_error(dtp, elf, fd, bufs, 1430 "failed to allocate space for probe")); 1431 } 1432 1433 mod = 1; 1434 (void) elf_flagdata(data_tgt, ELF_C_SET, ELF_F_DIRTY); 1435 1436 /* 1437 * This symbol may already have been marked to 1438 * be ignored by another relocation referencing 1439 * the same symbol or if this object file has 1440 * already been processed by an earlier link 1441 * invocation. 1442 */ 1443 if (rsym.st_shndx != SHN_SUNW_IGNORE) { 1444 rsym.st_shndx = SHN_SUNW_IGNORE; 1445 (void) gelf_update_sym(data_sym, ndx, &rsym); 1446 } 1447 } 1448 } 1449 1450 if (mod && elf_update(elf, ELF_C_WRITE) == -1) 1451 goto err; 1452 1453 (void) elf_end(elf); 1454 (void) close(fd); 1455 1456 while ((pair = bufs) != NULL) { 1457 bufs = pair->dlp_next; 1458 dt_free(dtp, pair->dlp_str); 1459 dt_free(dtp, pair->dlp_sym); 1460 dt_free(dtp, pair); 1461 } 1462 1463 return (0); 1464 1465 err: 1466 return (dt_link_error(dtp, elf, fd, bufs, 1467 "an error was encountered while processing %s", obj)); 1468 } 1469 1470 int dtrace_program_link(dtrace_hdl_t * dtp,dtrace_prog_t * pgp,uint_t dflags,const char * file,int objc,char * const objv[])1471 dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags, 1472 const char *file, int objc, char *const objv[]) 1473 { 1474 char drti[PATH_MAX]; 1475 dof_hdr_t *dof; 1476 int fd, status, i, cur; 1477 char *cmd, tmp; 1478 size_t len; 1479 int eprobes = 0, ret = 0; 1480 1481 /* 1482 * A NULL program indicates a special use in which we just link 1483 * together a bunch of object files specified in objv and then 1484 * unlink(2) those object files. 1485 */ 1486 if (pgp == NULL) { 1487 const char *fmt = "%s -o %s -r"; 1488 1489 len = snprintf(&tmp, 1, fmt, dtp->dt_ld_path, file) + 1; 1490 1491 for (i = 0; i < objc; i++) 1492 len += strlen(objv[i]) + 1; 1493 1494 cmd = alloca(len); 1495 1496 cur = snprintf(cmd, len, fmt, dtp->dt_ld_path, file); 1497 1498 for (i = 0; i < objc; i++) 1499 cur += snprintf(cmd + cur, len - cur, " %s", objv[i]); 1500 1501 if ((status = system(cmd)) == -1) { 1502 return (dt_link_error(dtp, NULL, -1, NULL, 1503 "failed to run %s: %s", dtp->dt_ld_path, 1504 strerror(errno))); 1505 } 1506 1507 if (WIFSIGNALED(status)) { 1508 return (dt_link_error(dtp, NULL, -1, NULL, 1509 "failed to link %s: %s failed due to signal %d", 1510 file, dtp->dt_ld_path, WTERMSIG(status))); 1511 } 1512 1513 if (WEXITSTATUS(status) != 0) { 1514 return (dt_link_error(dtp, NULL, -1, NULL, 1515 "failed to link %s: %s exited with status %d\n", 1516 file, dtp->dt_ld_path, WEXITSTATUS(status))); 1517 } 1518 1519 for (i = 0; i < objc; i++) { 1520 if (strcmp(objv[i], file) != 0) 1521 (void) unlink(objv[i]); 1522 } 1523 1524 return (0); 1525 } 1526 1527 for (i = 0; i < objc; i++) { 1528 if (process_obj(dtp, objv[i], &eprobes) != 0) 1529 return (-1); /* errno is set for us */ 1530 } 1531 1532 /* 1533 * If there are is-enabled probes then we need to force use of DOF 1534 * version 2. 1535 */ 1536 if (eprobes && pgp->dp_dofversion < DOF_VERSION_2) 1537 pgp->dp_dofversion = DOF_VERSION_2; 1538 1539 if ((dof = dtrace_dof_create(dtp, pgp, dflags)) == NULL) 1540 return (-1); /* errno is set for us */ 1541 1542 /* 1543 * Create a temporary file and then unlink it if we're going to 1544 * combine it with drti.o later. We can still refer to it in child 1545 * processes as /dev/fd/<fd>. 1546 */ 1547 if ((fd = open64(file, O_RDWR | O_CREAT | O_TRUNC, 0666)) == -1) { 1548 return (dt_link_error(dtp, NULL, -1, NULL, 1549 "failed to open %s: %s", file, strerror(errno))); 1550 } 1551 1552 /* 1553 * If -xlinktype=DOF has been selected, just write out the DOF. 1554 * Otherwise proceed to the default of generating and linking ELF. 1555 */ 1556 switch (dtp->dt_linktype) { 1557 case DT_LTYP_DOF: 1558 if (dt_write(dtp, fd, dof, dof->dofh_filesz) < dof->dofh_filesz) 1559 ret = errno; 1560 1561 if (close(fd) != 0 && ret == 0) 1562 ret = errno; 1563 1564 if (ret != 0) { 1565 return (dt_link_error(dtp, NULL, -1, NULL, 1566 "failed to write %s: %s", file, strerror(ret))); 1567 } 1568 1569 return (0); 1570 1571 case DT_LTYP_ELF: 1572 break; /* fall through to the rest of dtrace_program_link() */ 1573 1574 default: 1575 return (dt_link_error(dtp, NULL, -1, NULL, 1576 "invalid link type %u\n", dtp->dt_linktype)); 1577 } 1578 1579 1580 if (!dtp->dt_lazyload) 1581 (void) unlink(file); 1582 1583 if (dtp->dt_oflags & DTRACE_O_LP64) 1584 status = dump_elf64(dtp, dof, fd); 1585 else 1586 status = dump_elf32(dtp, dof, fd); 1587 1588 if (status != 0 || lseek(fd, 0, SEEK_SET) != 0) { 1589 return (dt_link_error(dtp, NULL, -1, NULL, 1590 "failed to write %s: %s", file, strerror(errno))); 1591 } 1592 1593 if (!dtp->dt_lazyload) { 1594 const char *fmt = "%s -o %s -r -Blocal -Breduce /dev/fd/%d %s"; 1595 1596 if (dtp->dt_oflags & DTRACE_O_LP64) { 1597 (void) snprintf(drti, sizeof (drti), 1598 "%s/64/drti.o", _dtrace_libdir); 1599 } else { 1600 (void) snprintf(drti, sizeof (drti), 1601 "%s/drti.o", _dtrace_libdir); 1602 } 1603 1604 len = snprintf(&tmp, 1, fmt, dtp->dt_ld_path, file, fd, 1605 drti) + 1; 1606 1607 cmd = alloca(len); 1608 1609 (void) snprintf(cmd, len, fmt, dtp->dt_ld_path, file, fd, drti); 1610 1611 if ((status = system(cmd)) == -1) { 1612 ret = dt_link_error(dtp, NULL, -1, NULL, 1613 "failed to run %s: %s", dtp->dt_ld_path, 1614 strerror(errno)); 1615 goto done; 1616 } 1617 1618 (void) close(fd); /* release temporary file */ 1619 1620 if (WIFSIGNALED(status)) { 1621 ret = dt_link_error(dtp, NULL, -1, NULL, 1622 "failed to link %s: %s failed due to signal %d", 1623 file, dtp->dt_ld_path, WTERMSIG(status)); 1624 goto done; 1625 } 1626 1627 if (WEXITSTATUS(status) != 0) { 1628 ret = dt_link_error(dtp, NULL, -1, NULL, 1629 "failed to link %s: %s exited with status %d\n", 1630 file, dtp->dt_ld_path, WEXITSTATUS(status)); 1631 goto done; 1632 } 1633 } else { 1634 (void) close(fd); 1635 } 1636 1637 done: 1638 dtrace_dof_destroy(dtp, dof); 1639 return (ret); 1640 } 1641