dt_link.c revision 260670
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 */ 26 27#pragma ident "%Z%%M% %I% %E% SMI" 28 29#define ELF_TARGET_ALL 30#include <elf.h> 31 32#include <sys/types.h> 33#if defined(sun) 34#include <sys/sysmacros.h> 35#else 36#define P2ROUNDUP(x, align) (-(-(x) & -(align))) 37#endif 38 39#include <unistd.h> 40#include <strings.h> 41#if defined(sun) 42#include <alloca.h> 43#endif 44#include <limits.h> 45#include <stddef.h> 46#include <stdlib.h> 47#include <stdio.h> 48#include <fcntl.h> 49#include <errno.h> 50#if defined(sun) 51#include <wait.h> 52#else 53#include <sys/wait.h> 54#include <libelf.h> 55#include <gelf.h> 56#include <sys/mman.h> 57#endif 58#include <assert.h> 59#include <sys/ipc.h> 60 61#include <dt_impl.h> 62#include <dt_provider.h> 63#include <dt_program.h> 64#include <dt_string.h> 65 66#define ESHDR_NULL 0 67#define ESHDR_SHSTRTAB 1 68#define ESHDR_DOF 2 69#define ESHDR_STRTAB 3 70#define ESHDR_SYMTAB 4 71#define ESHDR_REL 5 72#define ESHDR_NUM 6 73 74#define PWRITE_SCN(index, data) \ 75 (lseek64(fd, (off64_t)elf_file.shdr[(index)].sh_offset, SEEK_SET) != \ 76 (off64_t)elf_file.shdr[(index)].sh_offset || \ 77 dt_write(dtp, fd, (data), elf_file.shdr[(index)].sh_size) != \ 78 elf_file.shdr[(index)].sh_size) 79 80static const char DTRACE_SHSTRTAB32[] = "\0" 81".shstrtab\0" /* 1 */ 82".SUNW_dof\0" /* 11 */ 83".strtab\0" /* 21 */ 84".symtab\0" /* 29 */ 85#ifdef __sparc 86".rela.SUNW_dof"; /* 37 */ 87#else 88".rel.SUNW_dof"; /* 37 */ 89#endif 90 91static const char DTRACE_SHSTRTAB64[] = "\0" 92".shstrtab\0" /* 1 */ 93".SUNW_dof\0" /* 11 */ 94".strtab\0" /* 21 */ 95".symtab\0" /* 29 */ 96".rela.SUNW_dof"; /* 37 */ 97 98static const char DOFSTR[] = "__SUNW_dof"; 99static const char DOFLAZYSTR[] = "___SUNW_dof"; 100 101typedef struct dt_link_pair { 102 struct dt_link_pair *dlp_next; /* next pair in linked list */ 103 void *dlp_str; /* buffer for string table */ 104 void *dlp_sym; /* buffer for symbol table */ 105} dt_link_pair_t; 106 107typedef struct dof_elf32 { 108 uint32_t de_nrel; /* relocation count */ 109#ifdef __sparc 110 Elf32_Rela *de_rel; /* array of relocations for sparc */ 111#else 112 Elf32_Rel *de_rel; /* array of relocations for x86 */ 113#endif 114 uint32_t de_nsym; /* symbol count */ 115 Elf32_Sym *de_sym; /* array of symbols */ 116 uint32_t de_strlen; /* size of of string table */ 117 char *de_strtab; /* string table */ 118 uint32_t de_global; /* index of the first global symbol */ 119} dof_elf32_t; 120 121static int 122prepare_elf32(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf32_t *dep) 123{ 124 dof_sec_t *dofs, *s; 125 dof_relohdr_t *dofrh; 126 dof_relodesc_t *dofr; 127 char *strtab; 128 int i, j, nrel; 129 size_t strtabsz = 1; 130 uint32_t count = 0; 131 size_t base; 132 Elf32_Sym *sym; 133#ifdef __sparc 134 Elf32_Rela *rel; 135#else 136 Elf32_Rel *rel; 137#endif 138 139 /*LINTED*/ 140 dofs = (dof_sec_t *)((char *)dof + dof->dofh_secoff); 141 142 /* 143 * First compute the size of the string table and the number of 144 * relocations present in the DOF. 145 */ 146 for (i = 0; i < dof->dofh_secnum; i++) { 147 if (dofs[i].dofs_type != DOF_SECT_URELHDR) 148 continue; 149 150 /*LINTED*/ 151 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset); 152 153 s = &dofs[dofrh->dofr_strtab]; 154 strtab = (char *)dof + s->dofs_offset; 155 assert(strtab[0] == '\0'); 156 strtabsz += s->dofs_size - 1; 157 158 s = &dofs[dofrh->dofr_relsec]; 159 /*LINTED*/ 160 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset); 161 count += s->dofs_size / s->dofs_entsize; 162 } 163 164 dep->de_strlen = strtabsz; 165 dep->de_nrel = count; 166 dep->de_nsym = count + 1; /* the first symbol is always null */ 167 168 if (dtp->dt_lazyload) { 169 dep->de_strlen += sizeof (DOFLAZYSTR); 170 dep->de_nsym++; 171 } else { 172 dep->de_strlen += sizeof (DOFSTR); 173 dep->de_nsym++; 174 } 175 176 if ((dep->de_rel = calloc(dep->de_nrel, 177 sizeof (dep->de_rel[0]))) == NULL) { 178 return (dt_set_errno(dtp, EDT_NOMEM)); 179 } 180 181 if ((dep->de_sym = calloc(dep->de_nsym, sizeof (Elf32_Sym))) == NULL) { 182 free(dep->de_rel); 183 return (dt_set_errno(dtp, EDT_NOMEM)); 184 } 185 186 if ((dep->de_strtab = calloc(dep->de_strlen, 1)) == NULL) { 187 free(dep->de_rel); 188 free(dep->de_sym); 189 return (dt_set_errno(dtp, EDT_NOMEM)); 190 } 191 192 count = 0; 193 strtabsz = 1; 194 dep->de_strtab[0] = '\0'; 195 rel = dep->de_rel; 196 sym = dep->de_sym; 197 dep->de_global = 1; 198 199 /* 200 * The first symbol table entry must be zeroed and is always ignored. 201 */ 202 bzero(sym, sizeof (Elf32_Sym)); 203 sym++; 204 205 /* 206 * Take a second pass through the DOF sections filling in the 207 * memory we allocated. 208 */ 209 for (i = 0; i < dof->dofh_secnum; i++) { 210 if (dofs[i].dofs_type != DOF_SECT_URELHDR) 211 continue; 212 213 /*LINTED*/ 214 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset); 215 216 s = &dofs[dofrh->dofr_strtab]; 217 strtab = (char *)dof + s->dofs_offset; 218 bcopy(strtab + 1, dep->de_strtab + strtabsz, s->dofs_size); 219 base = strtabsz; 220 strtabsz += s->dofs_size - 1; 221 222 s = &dofs[dofrh->dofr_relsec]; 223 /*LINTED*/ 224 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset); 225 nrel = s->dofs_size / s->dofs_entsize; 226 227 s = &dofs[dofrh->dofr_tgtsec]; 228 229 for (j = 0; j < nrel; j++) { 230#if defined(__arm__) 231/* XXX */ 232printf("%s:%s(%d): DOODAD\n",__FUNCTION__,__FILE__,__LINE__); 233#elif defined(__ia64__) 234/* XXX */ 235printf("%s:%s(%d): DOODAD\n",__FUNCTION__,__FILE__,__LINE__); 236#elif defined(__i386) || defined(__amd64) 237 rel->r_offset = s->dofs_offset + 238 dofr[j].dofr_offset; 239 rel->r_info = ELF32_R_INFO(count + dep->de_global, 240 R_386_32); 241#elif defined(__mips__) 242/* XXX */ 243printf("%s:%s(%d): DOODAD\n",__FUNCTION__,__FILE__,__LINE__); 244#elif defined(__powerpc__) 245 /* 246 * Add 4 bytes to hit the low half of this 64-bit 247 * big-endian address. 248 */ 249 rel->r_offset = s->dofs_offset + 250 dofr[j].dofr_offset + 4; 251 rel->r_info = ELF32_R_INFO(count + dep->de_global, 252 R_PPC_REL32); 253#elif defined(__sparc) 254 /* 255 * Add 4 bytes to hit the low half of this 64-bit 256 * big-endian address. 257 */ 258 rel->r_offset = s->dofs_offset + 259 dofr[j].dofr_offset + 4; 260 rel->r_info = ELF32_R_INFO(count + dep->de_global, 261 R_SPARC_32); 262#else 263#error unknown ISA 264#endif 265 266 sym->st_name = base + dofr[j].dofr_name - 1; 267 sym->st_value = 0; 268 sym->st_size = 0; 269 sym->st_info = ELF32_ST_INFO(STB_GLOBAL, STT_FUNC); 270 sym->st_other = 0; 271 sym->st_shndx = SHN_UNDEF; 272 273 rel++; 274 sym++; 275 count++; 276 } 277 } 278 279 /* 280 * Add a symbol for the DOF itself. We use a different symbol for 281 * lazily and actively loaded DOF to make them easy to distinguish. 282 */ 283 sym->st_name = strtabsz; 284 sym->st_value = 0; 285 sym->st_size = dof->dofh_filesz; 286 sym->st_info = ELF32_ST_INFO(STB_GLOBAL, STT_OBJECT); 287 sym->st_other = 0; 288 sym->st_shndx = ESHDR_DOF; 289 sym++; 290 291 if (dtp->dt_lazyload) { 292 bcopy(DOFLAZYSTR, dep->de_strtab + strtabsz, 293 sizeof (DOFLAZYSTR)); 294 strtabsz += sizeof (DOFLAZYSTR); 295 } else { 296 bcopy(DOFSTR, dep->de_strtab + strtabsz, sizeof (DOFSTR)); 297 strtabsz += sizeof (DOFSTR); 298 } 299 300 assert(count == dep->de_nrel); 301 assert(strtabsz == dep->de_strlen); 302 303 return (0); 304} 305 306 307typedef struct dof_elf64 { 308 uint32_t de_nrel; 309 Elf64_Rela *de_rel; 310 uint32_t de_nsym; 311 Elf64_Sym *de_sym; 312 313 uint32_t de_strlen; 314 char *de_strtab; 315 316 uint32_t de_global; 317} dof_elf64_t; 318 319static int 320prepare_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf64_t *dep) 321{ 322 dof_sec_t *dofs, *s; 323 dof_relohdr_t *dofrh; 324 dof_relodesc_t *dofr; 325 char *strtab; 326 int i, j, nrel; 327 size_t strtabsz = 1; 328 uint32_t count = 0; 329 size_t base; 330 Elf64_Sym *sym; 331 Elf64_Rela *rel; 332 333 /*LINTED*/ 334 dofs = (dof_sec_t *)((char *)dof + dof->dofh_secoff); 335 336 /* 337 * First compute the size of the string table and the number of 338 * relocations present in the DOF. 339 */ 340 for (i = 0; i < dof->dofh_secnum; i++) { 341 if (dofs[i].dofs_type != DOF_SECT_URELHDR) 342 continue; 343 344 /*LINTED*/ 345 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset); 346 347 s = &dofs[dofrh->dofr_strtab]; 348 strtab = (char *)dof + s->dofs_offset; 349 assert(strtab[0] == '\0'); 350 strtabsz += s->dofs_size - 1; 351 352 s = &dofs[dofrh->dofr_relsec]; 353 /*LINTED*/ 354 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset); 355 count += s->dofs_size / s->dofs_entsize; 356 } 357 358 dep->de_strlen = strtabsz; 359 dep->de_nrel = count; 360 dep->de_nsym = count + 1; /* the first symbol is always null */ 361 362 if (dtp->dt_lazyload) { 363 dep->de_strlen += sizeof (DOFLAZYSTR); 364 dep->de_nsym++; 365 } else { 366 dep->de_strlen += sizeof (DOFSTR); 367 dep->de_nsym++; 368 } 369 370 if ((dep->de_rel = calloc(dep->de_nrel, 371 sizeof (dep->de_rel[0]))) == NULL) { 372 return (dt_set_errno(dtp, EDT_NOMEM)); 373 } 374 375 if ((dep->de_sym = calloc(dep->de_nsym, sizeof (Elf64_Sym))) == NULL) { 376 free(dep->de_rel); 377 return (dt_set_errno(dtp, EDT_NOMEM)); 378 } 379 380 if ((dep->de_strtab = calloc(dep->de_strlen, 1)) == NULL) { 381 free(dep->de_rel); 382 free(dep->de_sym); 383 return (dt_set_errno(dtp, EDT_NOMEM)); 384 } 385 386 count = 0; 387 strtabsz = 1; 388 dep->de_strtab[0] = '\0'; 389 rel = dep->de_rel; 390 sym = dep->de_sym; 391 dep->de_global = 1; 392 393 /* 394 * The first symbol table entry must be zeroed and is always ignored. 395 */ 396 bzero(sym, sizeof (Elf64_Sym)); 397 sym++; 398 399 /* 400 * Take a second pass through the DOF sections filling in the 401 * memory we allocated. 402 */ 403 for (i = 0; i < dof->dofh_secnum; i++) { 404 if (dofs[i].dofs_type != DOF_SECT_URELHDR) 405 continue; 406 407 /*LINTED*/ 408 dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset); 409 410 s = &dofs[dofrh->dofr_strtab]; 411 strtab = (char *)dof + s->dofs_offset; 412 bcopy(strtab + 1, dep->de_strtab + strtabsz, s->dofs_size); 413 base = strtabsz; 414 strtabsz += s->dofs_size - 1; 415 416 s = &dofs[dofrh->dofr_relsec]; 417 /*LINTED*/ 418 dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset); 419 nrel = s->dofs_size / s->dofs_entsize; 420 421 s = &dofs[dofrh->dofr_tgtsec]; 422 423 for (j = 0; j < nrel; j++) { 424#ifdef DOODAD 425#if defined(__arm__) 426/* XXX */ 427#elif defined(__ia64__) 428/* XXX */ 429#elif defined(__mips__) 430/* XXX */ 431#elif defined(__powerpc__) 432 rel->r_offset = s->dofs_offset + 433 dofr[j].dofr_offset; 434 rel->r_info = ELF64_R_INFO(count + dep->de_global, 435 R_PPC64_REL64); 436#elif defined(__i386) || defined(__amd64) 437 rel->r_offset = s->dofs_offset + 438 dofr[j].dofr_offset; 439 rel->r_info = ELF64_R_INFO(count + dep->de_global, 440 R_AMD64_64); 441#elif defined(__sparc) 442 rel->r_offset = s->dofs_offset + 443 dofr[j].dofr_offset; 444 rel->r_info = ELF64_R_INFO(count + dep->de_global, 445 R_SPARC_64); 446#else 447#error unknown ISA 448#endif 449#endif 450 451 sym->st_name = base + dofr[j].dofr_name - 1; 452 sym->st_value = 0; 453 sym->st_size = 0; 454 sym->st_info = GELF_ST_INFO(STB_GLOBAL, STT_FUNC); 455 sym->st_other = 0; 456 sym->st_shndx = SHN_UNDEF; 457 458 rel++; 459 sym++; 460 count++; 461 } 462 } 463 464 /* 465 * Add a symbol for the DOF itself. We use a different symbol for 466 * lazily and actively loaded DOF to make them easy to distinguish. 467 */ 468 sym->st_name = strtabsz; 469 sym->st_value = 0; 470 sym->st_size = dof->dofh_filesz; 471 sym->st_info = GELF_ST_INFO(STB_GLOBAL, STT_OBJECT); 472 sym->st_other = 0; 473 sym->st_shndx = ESHDR_DOF; 474 sym++; 475 476 if (dtp->dt_lazyload) { 477 bcopy(DOFLAZYSTR, dep->de_strtab + strtabsz, 478 sizeof (DOFLAZYSTR)); 479 strtabsz += sizeof (DOFLAZYSTR); 480 } else { 481 bcopy(DOFSTR, dep->de_strtab + strtabsz, sizeof (DOFSTR)); 482 strtabsz += sizeof (DOFSTR); 483 } 484 485 assert(count == dep->de_nrel); 486 assert(strtabsz == dep->de_strlen); 487 488 return (0); 489} 490 491/* 492 * Write out an ELF32 file prologue consisting of a header, section headers, 493 * and a section header string table. The DOF data will follow this prologue 494 * and complete the contents of the given ELF file. 495 */ 496static int 497dump_elf32(dtrace_hdl_t *dtp, const dof_hdr_t *dof, int fd) 498{ 499 struct { 500 Elf32_Ehdr ehdr; 501 Elf32_Shdr shdr[ESHDR_NUM]; 502 } elf_file; 503 504 Elf32_Shdr *shp; 505 Elf32_Off off; 506 dof_elf32_t de; 507 int ret = 0; 508 uint_t nshdr; 509 510 if (prepare_elf32(dtp, dof, &de) != 0) 511 return (-1); /* errno is set for us */ 512 513 /* 514 * If there are no relocations, we only need enough sections for 515 * the shstrtab and the DOF. 516 */ 517 nshdr = de.de_nrel == 0 ? ESHDR_SYMTAB + 1 : ESHDR_NUM; 518 519 bzero(&elf_file, sizeof (elf_file)); 520 521 elf_file.ehdr.e_ident[EI_MAG0] = ELFMAG0; 522 elf_file.ehdr.e_ident[EI_MAG1] = ELFMAG1; 523 elf_file.ehdr.e_ident[EI_MAG2] = ELFMAG2; 524 elf_file.ehdr.e_ident[EI_MAG3] = ELFMAG3; 525 elf_file.ehdr.e_ident[EI_VERSION] = EV_CURRENT; 526 elf_file.ehdr.e_ident[EI_CLASS] = ELFCLASS32; 527#if BYTE_ORDER == _BIG_ENDIAN 528 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2MSB; 529#else 530 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2LSB; 531#endif 532#if defined(__FreeBSD__) 533 elf_file.ehdr.e_ident[EI_OSABI] = ELFOSABI_FREEBSD; 534#endif 535 elf_file.ehdr.e_type = ET_REL; 536#if defined(__arm__) 537 elf_file.ehdr.e_machine = EM_ARM; 538#elif defined(__ia64__) 539 elf_file.ehdr.e_machine = EM_IA_64; 540#elif defined(__mips__) 541 elf_file.ehdr.e_machine = EM_MIPS; 542#elif defined(__powerpc__) 543 elf_file.ehdr.e_machine = EM_PPC; 544#elif defined(__sparc) 545 elf_file.ehdr.e_machine = EM_SPARC; 546#elif defined(__i386) || defined(__amd64) 547 elf_file.ehdr.e_machine = EM_386; 548#endif 549 elf_file.ehdr.e_version = EV_CURRENT; 550 elf_file.ehdr.e_shoff = sizeof (Elf32_Ehdr); 551 elf_file.ehdr.e_ehsize = sizeof (Elf32_Ehdr); 552 elf_file.ehdr.e_phentsize = sizeof (Elf32_Phdr); 553 elf_file.ehdr.e_shentsize = sizeof (Elf32_Shdr); 554 elf_file.ehdr.e_shnum = nshdr; 555 elf_file.ehdr.e_shstrndx = ESHDR_SHSTRTAB; 556 off = sizeof (elf_file) + nshdr * sizeof (Elf32_Shdr); 557 558 shp = &elf_file.shdr[ESHDR_SHSTRTAB]; 559 shp->sh_name = 1; /* DTRACE_SHSTRTAB32[1] = ".shstrtab" */ 560 shp->sh_type = SHT_STRTAB; 561 shp->sh_offset = off; 562 shp->sh_size = sizeof (DTRACE_SHSTRTAB32); 563 shp->sh_addralign = sizeof (char); 564 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8); 565 566 shp = &elf_file.shdr[ESHDR_DOF]; 567 shp->sh_name = 11; /* DTRACE_SHSTRTAB32[11] = ".SUNW_dof" */ 568 shp->sh_flags = SHF_ALLOC; 569 shp->sh_type = SHT_SUNW_dof; 570 shp->sh_offset = off; 571 shp->sh_size = dof->dofh_filesz; 572 shp->sh_addralign = 8; 573 off = shp->sh_offset + shp->sh_size; 574 575 shp = &elf_file.shdr[ESHDR_STRTAB]; 576 shp->sh_name = 21; /* DTRACE_SHSTRTAB32[21] = ".strtab" */ 577 shp->sh_flags = SHF_ALLOC; 578 shp->sh_type = SHT_STRTAB; 579 shp->sh_offset = off; 580 shp->sh_size = de.de_strlen; 581 shp->sh_addralign = sizeof (char); 582 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 4); 583 584 shp = &elf_file.shdr[ESHDR_SYMTAB]; 585 shp->sh_name = 29; /* DTRACE_SHSTRTAB32[29] = ".symtab" */ 586 shp->sh_flags = SHF_ALLOC; 587 shp->sh_type = SHT_SYMTAB; 588 shp->sh_entsize = sizeof (Elf32_Sym); 589 shp->sh_link = ESHDR_STRTAB; 590 shp->sh_offset = off; 591 shp->sh_info = de.de_global; 592 shp->sh_size = de.de_nsym * sizeof (Elf32_Sym); 593 shp->sh_addralign = 4; 594 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 4); 595 596 if (de.de_nrel == 0) { 597 if (dt_write(dtp, fd, &elf_file, 598 sizeof (elf_file)) != sizeof (elf_file) || 599 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB32) || 600 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) || 601 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) || 602 PWRITE_SCN(ESHDR_DOF, dof)) { 603 ret = dt_set_errno(dtp, errno); 604 } 605 } else { 606 shp = &elf_file.shdr[ESHDR_REL]; 607 shp->sh_name = 37; /* DTRACE_SHSTRTAB32[37] = ".rel.SUNW_dof" */ 608 shp->sh_flags = SHF_ALLOC; 609#ifdef __sparc 610 shp->sh_type = SHT_RELA; 611#else 612 shp->sh_type = SHT_REL; 613#endif 614 shp->sh_entsize = sizeof (de.de_rel[0]); 615 shp->sh_link = ESHDR_SYMTAB; 616 shp->sh_info = ESHDR_DOF; 617 shp->sh_offset = off; 618 shp->sh_size = de.de_nrel * sizeof (de.de_rel[0]); 619 shp->sh_addralign = 4; 620 621 if (dt_write(dtp, fd, &elf_file, 622 sizeof (elf_file)) != sizeof (elf_file) || 623 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB32) || 624 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) || 625 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) || 626 PWRITE_SCN(ESHDR_REL, de.de_rel) || 627 PWRITE_SCN(ESHDR_DOF, dof)) { 628 ret = dt_set_errno(dtp, errno); 629 } 630 } 631 632 free(de.de_strtab); 633 free(de.de_sym); 634 free(de.de_rel); 635 636 return (ret); 637} 638 639/* 640 * Write out an ELF64 file prologue consisting of a header, section headers, 641 * and a section header string table. The DOF data will follow this prologue 642 * and complete the contents of the given ELF file. 643 */ 644static int 645dump_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, int fd) 646{ 647 struct { 648 Elf64_Ehdr ehdr; 649 Elf64_Shdr shdr[ESHDR_NUM]; 650 } elf_file; 651 652 Elf64_Shdr *shp; 653 Elf64_Off off; 654 dof_elf64_t de; 655 int ret = 0; 656 uint_t nshdr; 657 658 if (prepare_elf64(dtp, dof, &de) != 0) 659 return (-1); /* errno is set for us */ 660 661 /* 662 * If there are no relocations, we only need enough sections for 663 * the shstrtab and the DOF. 664 */ 665 nshdr = de.de_nrel == 0 ? ESHDR_SYMTAB + 1 : ESHDR_NUM; 666 667 bzero(&elf_file, sizeof (elf_file)); 668 669 elf_file.ehdr.e_ident[EI_MAG0] = ELFMAG0; 670 elf_file.ehdr.e_ident[EI_MAG1] = ELFMAG1; 671 elf_file.ehdr.e_ident[EI_MAG2] = ELFMAG2; 672 elf_file.ehdr.e_ident[EI_MAG3] = ELFMAG3; 673 elf_file.ehdr.e_ident[EI_VERSION] = EV_CURRENT; 674 elf_file.ehdr.e_ident[EI_CLASS] = ELFCLASS64; 675#if BYTE_ORDER == _BIG_ENDIAN 676 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2MSB; 677#else 678 elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2LSB; 679#endif 680#if defined(__FreeBSD__) 681 elf_file.ehdr.e_ident[EI_OSABI] = ELFOSABI_FREEBSD; 682#endif 683 elf_file.ehdr.e_type = ET_REL; 684#if defined(__arm__) 685 elf_file.ehdr.e_machine = EM_ARM; 686#elif defined(__ia64__) 687 elf_file.ehdr.e_machine = EM_IA_64; 688#elif defined(__mips__) 689 elf_file.ehdr.e_machine = EM_MIPS; 690#elif defined(__powerpc__) 691 elf_file.ehdr.e_machine = EM_PPC; 692#elif defined(__sparc) 693 elf_file.ehdr.e_machine = EM_SPARCV9; 694#elif defined(__i386) || defined(__amd64) 695 elf_file.ehdr.e_machine = EM_AMD64; 696#endif 697 elf_file.ehdr.e_version = EV_CURRENT; 698 elf_file.ehdr.e_shoff = sizeof (Elf64_Ehdr); 699 elf_file.ehdr.e_ehsize = sizeof (Elf64_Ehdr); 700 elf_file.ehdr.e_phentsize = sizeof (Elf64_Phdr); 701 elf_file.ehdr.e_shentsize = sizeof (Elf64_Shdr); 702 elf_file.ehdr.e_shnum = nshdr; 703 elf_file.ehdr.e_shstrndx = ESHDR_SHSTRTAB; 704 off = sizeof (elf_file) + nshdr * sizeof (Elf64_Shdr); 705 706 shp = &elf_file.shdr[ESHDR_SHSTRTAB]; 707 shp->sh_name = 1; /* DTRACE_SHSTRTAB64[1] = ".shstrtab" */ 708 shp->sh_type = SHT_STRTAB; 709 shp->sh_offset = off; 710 shp->sh_size = sizeof (DTRACE_SHSTRTAB64); 711 shp->sh_addralign = sizeof (char); 712 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8); 713 714 shp = &elf_file.shdr[ESHDR_DOF]; 715 shp->sh_name = 11; /* DTRACE_SHSTRTAB64[11] = ".SUNW_dof" */ 716 shp->sh_flags = SHF_ALLOC; 717 shp->sh_type = SHT_SUNW_dof; 718 shp->sh_offset = off; 719 shp->sh_size = dof->dofh_filesz; 720 shp->sh_addralign = 8; 721 off = shp->sh_offset + shp->sh_size; 722 723 shp = &elf_file.shdr[ESHDR_STRTAB]; 724 shp->sh_name = 21; /* DTRACE_SHSTRTAB64[21] = ".strtab" */ 725 shp->sh_flags = SHF_ALLOC; 726 shp->sh_type = SHT_STRTAB; 727 shp->sh_offset = off; 728 shp->sh_size = de.de_strlen; 729 shp->sh_addralign = sizeof (char); 730 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8); 731 732 shp = &elf_file.shdr[ESHDR_SYMTAB]; 733 shp->sh_name = 29; /* DTRACE_SHSTRTAB64[29] = ".symtab" */ 734 shp->sh_flags = SHF_ALLOC; 735 shp->sh_type = SHT_SYMTAB; 736 shp->sh_entsize = sizeof (Elf64_Sym); 737 shp->sh_link = ESHDR_STRTAB; 738 shp->sh_offset = off; 739 shp->sh_info = de.de_global; 740 shp->sh_size = de.de_nsym * sizeof (Elf64_Sym); 741 shp->sh_addralign = 8; 742 off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8); 743 744 if (de.de_nrel == 0) { 745 if (dt_write(dtp, fd, &elf_file, 746 sizeof (elf_file)) != sizeof (elf_file) || 747 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB64) || 748 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) || 749 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) || 750 PWRITE_SCN(ESHDR_DOF, dof)) { 751 ret = dt_set_errno(dtp, errno); 752 } 753 } else { 754 shp = &elf_file.shdr[ESHDR_REL]; 755 shp->sh_name = 37; /* DTRACE_SHSTRTAB64[37] = ".rel.SUNW_dof" */ 756 shp->sh_flags = SHF_ALLOC; 757 shp->sh_type = SHT_RELA; 758 shp->sh_entsize = sizeof (de.de_rel[0]); 759 shp->sh_link = ESHDR_SYMTAB; 760 shp->sh_info = ESHDR_DOF; 761 shp->sh_offset = off; 762 shp->sh_size = de.de_nrel * sizeof (de.de_rel[0]); 763 shp->sh_addralign = 8; 764 765 if (dt_write(dtp, fd, &elf_file, 766 sizeof (elf_file)) != sizeof (elf_file) || 767 PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB64) || 768 PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) || 769 PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) || 770 PWRITE_SCN(ESHDR_REL, de.de_rel) || 771 PWRITE_SCN(ESHDR_DOF, dof)) { 772 ret = dt_set_errno(dtp, errno); 773 } 774 } 775 776 free(de.de_strtab); 777 free(de.de_sym); 778 free(de.de_rel); 779 780 return (ret); 781} 782 783static int 784dt_symtab_lookup(Elf_Data *data_sym, int nsym, uintptr_t addr, uint_t shn, 785 GElf_Sym *sym) 786{ 787 int i, ret = -1; 788 GElf_Sym s; 789 790 for (i = 0; i < nsym && gelf_getsym(data_sym, i, sym) != NULL; i++) { 791 if (GELF_ST_TYPE(sym->st_info) == STT_FUNC && 792 shn == sym->st_shndx && 793 sym->st_value <= addr && 794 addr < sym->st_value + sym->st_size) { 795 if (GELF_ST_BIND(sym->st_info) == STB_GLOBAL) 796 return (0); 797 798 ret = 0; 799 s = *sym; 800 } 801 } 802 803 if (ret == 0) 804 *sym = s; 805 return (ret); 806} 807 808#if defined(__arm__) 809/* XXX */ 810static int 811dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela, 812 uint32_t *off) 813{ 814printf("%s:%s(%d): DOODAD\n",__FUNCTION__,__FILE__,__LINE__); 815 return (0); 816} 817#elif defined(__ia64__) 818/* XXX */ 819static int 820dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela, 821 uint32_t *off) 822{ 823printf("%s:%s(%d): DOODAD\n",__FUNCTION__,__FILE__,__LINE__); 824 return (0); 825} 826#elif defined(__mips__) 827/* XXX */ 828static int 829dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela, 830 uint32_t *off) 831{ 832printf("%s:%s(%d): DOODAD\n",__FUNCTION__,__FILE__,__LINE__); 833 return (0); 834} 835#elif defined(__powerpc__) 836/* The sentinel is 'xor r3,r3,r3'. */ 837#define DT_OP_XOR_R3 0x7c631a78 838 839#define DT_OP_NOP 0x60000000 840#define DT_OP_BLR 0x4e800020 841 842/* This captures all forms of branching to address. */ 843#define DT_IS_BRANCH(inst) ((inst & 0xfc000000) == 0x48000000) 844#define DT_IS_BL(inst) (DT_IS_BRANCH(inst) && (inst & 0x01)) 845 846/* XXX */ 847static int 848dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela, 849 uint32_t *off) 850{ 851 uint32_t *ip; 852 853 if ((rela->r_offset & (sizeof (uint32_t) - 1)) != 0) 854 return (-1); 855 856 /*LINTED*/ 857 ip = (uint32_t *)(p + rela->r_offset); 858 859 /* 860 * We only know about some specific relocation types. 861 */ 862 if (GELF_R_TYPE(rela->r_info) != R_PPC_REL24 && 863 GELF_R_TYPE(rela->r_info) != R_PPC_PLTREL24) 864 return (-1); 865 866 /* 867 * We may have already processed this object file in an earlier linker 868 * invocation. Check to see if the present instruction sequence matches 869 * the one we would install below. 870 */ 871 if (isenabled) { 872 if (ip[0] == DT_OP_XOR_R3) { 873 (*off) += sizeof (ip[0]); 874 return (0); 875 } 876 } else { 877 if (ip[0] == DT_OP_NOP) { 878 (*off) += sizeof (ip[0]); 879 return (0); 880 } 881 } 882 883 /* 884 * We only expect branch to address instructions. 885 */ 886 if (!DT_IS_BRANCH(ip[0])) { 887 dt_dprintf("found %x instead of a branch instruction at %llx\n", 888 ip[0], (u_longlong_t)rela->r_offset); 889 return (-1); 890 } 891 892 if (isenabled) { 893 /* 894 * It would necessarily indicate incorrect usage if an is- 895 * enabled probe were tail-called so flag that as an error. 896 * It's also potentially (very) tricky to handle gracefully, 897 * but could be done if this were a desired use scenario. 898 */ 899 if (!DT_IS_BL(ip[0])) { 900 dt_dprintf("tail call to is-enabled probe at %llx\n", 901 (u_longlong_t)rela->r_offset); 902 return (-1); 903 } 904 905 ip[0] = DT_OP_XOR_R3; 906 (*off) += sizeof (ip[0]); 907 } else { 908 if (DT_IS_BL(ip[0])) 909 ip[0] = DT_OP_NOP; 910 else 911 ip[0] = DT_OP_BLR; 912 } 913 914 return (0); 915} 916 917#elif defined(__sparc) 918 919#define DT_OP_RET 0x81c7e008 920#define DT_OP_NOP 0x01000000 921#define DT_OP_CALL 0x40000000 922#define DT_OP_CLR_O0 0x90102000 923 924#define DT_IS_MOV_O7(inst) (((inst) & 0xffffe000) == 0x9e100000) 925#define DT_IS_RESTORE(inst) (((inst) & 0xc1f80000) == 0x81e80000) 926#define DT_IS_RETL(inst) (((inst) & 0xfff83fff) == 0x81c02008) 927 928#define DT_RS2(inst) ((inst) & 0x1f) 929#define DT_MAKE_RETL(reg) (0x81c02008 | ((reg) << 14)) 930 931/*ARGSUSED*/ 932static int 933dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela, 934 uint32_t *off) 935{ 936 uint32_t *ip; 937 938 if ((rela->r_offset & (sizeof (uint32_t) - 1)) != 0) 939 return (-1); 940 941 /*LINTED*/ 942 ip = (uint32_t *)(p + rela->r_offset); 943 944 /* 945 * We only know about some specific relocation types. 946 */ 947 if (GELF_R_TYPE(rela->r_info) != R_SPARC_WDISP30 && 948 GELF_R_TYPE(rela->r_info) != R_SPARC_WPLT30) 949 return (-1); 950 951 /* 952 * We may have already processed this object file in an earlier linker 953 * invocation. Check to see if the present instruction sequence matches 954 * the one we would install below. 955 */ 956 if (isenabled) { 957 if (ip[0] == DT_OP_NOP) { 958 (*off) += sizeof (ip[0]); 959 return (0); 960 } 961 } else { 962 if (DT_IS_RESTORE(ip[1])) { 963 if (ip[0] == DT_OP_RET) { 964 (*off) += sizeof (ip[0]); 965 return (0); 966 } 967 } else if (DT_IS_MOV_O7(ip[1])) { 968 if (DT_IS_RETL(ip[0])) 969 return (0); 970 } else { 971 if (ip[0] == DT_OP_NOP) { 972 (*off) += sizeof (ip[0]); 973 return (0); 974 } 975 } 976 } 977 978 /* 979 * We only expect call instructions with a displacement of 0. 980 */ 981 if (ip[0] != DT_OP_CALL) { 982 dt_dprintf("found %x instead of a call instruction at %llx\n", 983 ip[0], (u_longlong_t)rela->r_offset); 984 return (-1); 985 } 986 987 if (isenabled) { 988 /* 989 * It would necessarily indicate incorrect usage if an is- 990 * enabled probe were tail-called so flag that as an error. 991 * It's also potentially (very) tricky to handle gracefully, 992 * but could be done if this were a desired use scenario. 993 */ 994 if (DT_IS_RESTORE(ip[1]) || DT_IS_MOV_O7(ip[1])) { 995 dt_dprintf("tail call to is-enabled probe at %llx\n", 996 (u_longlong_t)rela->r_offset); 997 return (-1); 998 } 999 1000 1001 /* 1002 * On SPARC, we take advantage of the fact that the first 1003 * argument shares the same register as for the return value. 1004 * The macro handles the work of zeroing that register so we 1005 * don't need to do anything special here. We instrument the 1006 * instruction in the delay slot as we'll need to modify the 1007 * return register after that instruction has been emulated. 1008 */ 1009 ip[0] = DT_OP_NOP; 1010 (*off) += sizeof (ip[0]); 1011 } else { 1012 /* 1013 * If the call is followed by a restore, it's a tail call so 1014 * change the call to a ret. If the call if followed by a mov 1015 * of a register into %o7, it's a tail call in leaf context 1016 * so change the call to a retl-like instruction that returns 1017 * to that register value + 8 (rather than the typical %o7 + 1018 * 8); the delay slot instruction is left, but should have no 1019 * effect. Otherwise we change the call to be a nop. We 1020 * identify the subsequent instruction as the probe point in 1021 * all but the leaf tail-call case to ensure that arguments to 1022 * the probe are complete and consistent. An astute, though 1023 * largely hypothetical, observer would note that there is the 1024 * possibility of a false-positive probe firing if the function 1025 * contained a branch to the instruction in the delay slot of 1026 * the call. Fixing this would require significant in-kernel 1027 * modifications, and isn't worth doing until we see it in the 1028 * wild. 1029 */ 1030 if (DT_IS_RESTORE(ip[1])) { 1031 ip[0] = DT_OP_RET; 1032 (*off) += sizeof (ip[0]); 1033 } else if (DT_IS_MOV_O7(ip[1])) { 1034 ip[0] = DT_MAKE_RETL(DT_RS2(ip[1])); 1035 } else { 1036 ip[0] = DT_OP_NOP; 1037 (*off) += sizeof (ip[0]); 1038 } 1039 } 1040 1041 return (0); 1042} 1043 1044#elif defined(__i386) || defined(__amd64) 1045 1046#define DT_OP_NOP 0x90 1047#define DT_OP_RET 0xc3 1048#define DT_OP_CALL 0xe8 1049#define DT_OP_JMP32 0xe9 1050#define DT_OP_REX_RAX 0x48 1051#define DT_OP_XOR_EAX_0 0x33 1052#define DT_OP_XOR_EAX_1 0xc0 1053 1054static int 1055dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela, 1056 uint32_t *off) 1057{ 1058 uint8_t *ip = (uint8_t *)(p + rela->r_offset - 1); 1059 uint8_t ret; 1060 1061 /* 1062 * On x86, the first byte of the instruction is the call opcode and 1063 * the next four bytes are the 32-bit address; the relocation is for 1064 * the address operand. We back up the offset to the first byte of 1065 * the instruction. For is-enabled probes, we later advance the offset 1066 * so that it hits the first nop in the instruction sequence. 1067 */ 1068 (*off) -= 1; 1069 1070 /* 1071 * We only know about some specific relocation types. Luckily 1072 * these types have the same values on both 32-bit and 64-bit 1073 * x86 architectures. 1074 */ 1075 if (GELF_R_TYPE(rela->r_info) != R_386_PC32 && 1076 GELF_R_TYPE(rela->r_info) != R_386_PLT32) 1077 return (-1); 1078 1079 /* 1080 * We may have already processed this object file in an earlier linker 1081 * invocation. Check to see if the present instruction sequence matches 1082 * the one we would install. For is-enabled probes, we advance the 1083 * offset to the first nop instruction in the sequence to match the 1084 * text modification code below. 1085 */ 1086 if (!isenabled) { 1087 if ((ip[0] == DT_OP_NOP || ip[0] == DT_OP_RET) && 1088 ip[1] == DT_OP_NOP && ip[2] == DT_OP_NOP && 1089 ip[3] == DT_OP_NOP && ip[4] == DT_OP_NOP) 1090 return (0); 1091 } else if (dtp->dt_oflags & DTRACE_O_LP64) { 1092 if (ip[0] == DT_OP_REX_RAX && 1093 ip[1] == DT_OP_XOR_EAX_0 && ip[2] == DT_OP_XOR_EAX_1 && 1094 (ip[3] == DT_OP_NOP || ip[3] == DT_OP_RET) && 1095 ip[4] == DT_OP_NOP) { 1096 (*off) += 3; 1097 return (0); 1098 } 1099 } else { 1100 if (ip[0] == DT_OP_XOR_EAX_0 && ip[1] == DT_OP_XOR_EAX_1 && 1101 (ip[2] == DT_OP_NOP || ip[2] == DT_OP_RET) && 1102 ip[3] == DT_OP_NOP && ip[4] == DT_OP_NOP) { 1103 (*off) += 2; 1104 return (0); 1105 } 1106 } 1107 1108 /* 1109 * We expect either a call instrution with a 32-bit displacement or a 1110 * jmp instruction with a 32-bit displacement acting as a tail-call. 1111 */ 1112 if (ip[0] != DT_OP_CALL && ip[0] != DT_OP_JMP32) { 1113 dt_dprintf("found %x instead of a call or jmp instruction at " 1114 "%llx\n", ip[0], (u_longlong_t)rela->r_offset); 1115 return (-1); 1116 } 1117 1118 ret = (ip[0] == DT_OP_JMP32) ? DT_OP_RET : DT_OP_NOP; 1119 1120 /* 1121 * Establish the instruction sequence -- all nops for probes, and an 1122 * instruction to clear the return value register (%eax/%rax) followed 1123 * by nops for is-enabled probes. For is-enabled probes, we advance 1124 * the offset to the first nop. This isn't stricly necessary but makes 1125 * for more readable disassembly when the probe is enabled. 1126 */ 1127 if (!isenabled) { 1128 ip[0] = ret; 1129 ip[1] = DT_OP_NOP; 1130 ip[2] = DT_OP_NOP; 1131 ip[3] = DT_OP_NOP; 1132 ip[4] = DT_OP_NOP; 1133 } else if (dtp->dt_oflags & DTRACE_O_LP64) { 1134 ip[0] = DT_OP_REX_RAX; 1135 ip[1] = DT_OP_XOR_EAX_0; 1136 ip[2] = DT_OP_XOR_EAX_1; 1137 ip[3] = ret; 1138 ip[4] = DT_OP_NOP; 1139 (*off) += 3; 1140 } else { 1141 ip[0] = DT_OP_XOR_EAX_0; 1142 ip[1] = DT_OP_XOR_EAX_1; 1143 ip[2] = ret; 1144 ip[3] = DT_OP_NOP; 1145 ip[4] = DT_OP_NOP; 1146 (*off) += 2; 1147 } 1148 1149 return (0); 1150} 1151 1152#else 1153#error unknown ISA 1154#endif 1155 1156/*PRINTFLIKE5*/ 1157static int 1158dt_link_error(dtrace_hdl_t *dtp, Elf *elf, int fd, dt_link_pair_t *bufs, 1159 const char *format, ...) 1160{ 1161 va_list ap; 1162 dt_link_pair_t *pair; 1163 1164 va_start(ap, format); 1165 dt_set_errmsg(dtp, NULL, NULL, NULL, 0, format, ap); 1166 va_end(ap); 1167 1168 if (elf != NULL) 1169 (void) elf_end(elf); 1170 1171 if (fd >= 0) 1172 (void) close(fd); 1173 1174 while ((pair = bufs) != NULL) { 1175 bufs = pair->dlp_next; 1176 dt_free(dtp, pair->dlp_str); 1177 dt_free(dtp, pair->dlp_sym); 1178 dt_free(dtp, pair); 1179 } 1180 1181 return (dt_set_errno(dtp, EDT_COMPILER)); 1182} 1183 1184static int 1185process_obj(dtrace_hdl_t *dtp, const char *obj, int *eprobesp) 1186{ 1187 static const char dt_prefix[] = "__dtrace"; 1188 static const char dt_enabled[] = "enabled"; 1189 static const char dt_symprefix[] = "$dtrace"; 1190 static const char dt_symfmt[] = "%s%ld.%s"; 1191 int fd, i, ndx, eprobe, mod = 0; 1192 Elf *elf = NULL; 1193 GElf_Ehdr ehdr; 1194 Elf_Scn *scn_rel, *scn_sym, *scn_str, *scn_tgt; 1195 Elf_Data *data_rel, *data_sym, *data_str, *data_tgt; 1196 GElf_Shdr shdr_rel, shdr_sym, shdr_str, shdr_tgt; 1197 GElf_Sym rsym, fsym, dsym; 1198 GElf_Rela rela; 1199 char *s, *p, *r; 1200 char pname[DTRACE_PROVNAMELEN]; 1201 dt_provider_t *pvp; 1202 dt_probe_t *prp; 1203 uint32_t off, eclass, emachine1, emachine2; 1204 size_t symsize, nsym, isym, istr, len; 1205 key_t objkey; 1206 dt_link_pair_t *pair, *bufs = NULL; 1207 dt_strtab_t *strtab; 1208 1209 if ((fd = open64(obj, O_RDWR)) == -1) { 1210 return (dt_link_error(dtp, elf, fd, bufs, 1211 "failed to open %s: %s", obj, strerror(errno))); 1212 } 1213 1214 if ((elf = elf_begin(fd, ELF_C_RDWR, NULL)) == NULL) { 1215 return (dt_link_error(dtp, elf, fd, bufs, 1216 "failed to process %s: %s", obj, elf_errmsg(elf_errno()))); 1217 } 1218 1219 switch (elf_kind(elf)) { 1220 case ELF_K_ELF: 1221 break; 1222 case ELF_K_AR: 1223 return (dt_link_error(dtp, elf, fd, bufs, "archives are not " 1224 "permitted; use the contents of the archive instead: %s", 1225 obj)); 1226 default: 1227 return (dt_link_error(dtp, elf, fd, bufs, 1228 "invalid file type: %s", obj)); 1229 } 1230 1231 if (gelf_getehdr(elf, &ehdr) == NULL) { 1232 return (dt_link_error(dtp, elf, fd, bufs, "corrupt file: %s", 1233 obj)); 1234 } 1235 1236 if (dtp->dt_oflags & DTRACE_O_LP64) { 1237 eclass = ELFCLASS64; 1238#if defined(__ia64__) 1239 emachine1 = emachine2 = EM_IA_64; 1240#elif defined(__mips__) 1241 emachine1 = emachine2 = EM_MIPS; 1242#elif defined(__powerpc__) 1243 emachine1 = emachine2 = EM_PPC64; 1244#elif defined(__sparc) 1245 emachine1 = emachine2 = EM_SPARCV9; 1246#elif defined(__i386) || defined(__amd64) 1247 emachine1 = emachine2 = EM_AMD64; 1248#endif 1249 symsize = sizeof (Elf64_Sym); 1250 } else { 1251 eclass = ELFCLASS32; 1252#if defined(__arm__) 1253 emachine1 = emachine2 = EM_ARM; 1254#elif defined(__mips__) 1255 emachine1 = emachine2 = EM_MIPS; 1256#elif defined(__powerpc__) 1257 emachine1 = emachine2 = EM_PPC; 1258#elif defined(__sparc) 1259 emachine1 = EM_SPARC; 1260 emachine2 = EM_SPARC32PLUS; 1261#elif defined(__i386) || defined(__amd64) || defined(__ia64__) 1262 emachine1 = emachine2 = EM_386; 1263#endif 1264 symsize = sizeof (Elf32_Sym); 1265 } 1266 1267 if (ehdr.e_ident[EI_CLASS] != eclass) { 1268 return (dt_link_error(dtp, elf, fd, bufs, 1269 "incorrect ELF class for object file: %s", obj)); 1270 } 1271 1272 if (ehdr.e_machine != emachine1 && ehdr.e_machine != emachine2) { 1273 return (dt_link_error(dtp, elf, fd, bufs, 1274 "incorrect ELF machine type for object file: %s", obj)); 1275 } 1276 1277 /* 1278 * We use this token as a relatively unique handle for this file on the 1279 * system in order to disambiguate potential conflicts between files of 1280 * the same name which contain identially named local symbols. 1281 */ 1282 if ((objkey = ftok(obj, 0)) == (key_t)-1) { 1283 return (dt_link_error(dtp, elf, fd, bufs, 1284 "failed to generate unique key for object file: %s", obj)); 1285 } 1286 1287 scn_rel = NULL; 1288 while ((scn_rel = elf_nextscn(elf, scn_rel)) != NULL) { 1289 if (gelf_getshdr(scn_rel, &shdr_rel) == NULL) 1290 goto err; 1291 1292 /* 1293 * Skip any non-relocation sections. 1294 */ 1295 if (shdr_rel.sh_type != SHT_RELA && shdr_rel.sh_type != SHT_REL) 1296 continue; 1297 1298 if ((data_rel = elf_getdata(scn_rel, NULL)) == NULL) 1299 goto err; 1300 1301 /* 1302 * Grab the section, section header and section data for the 1303 * symbol table that this relocation section references. 1304 */ 1305 if ((scn_sym = elf_getscn(elf, shdr_rel.sh_link)) == NULL || 1306 gelf_getshdr(scn_sym, &shdr_sym) == NULL || 1307 (data_sym = elf_getdata(scn_sym, NULL)) == NULL) 1308 goto err; 1309 1310 /* 1311 * Ditto for that symbol table's string table. 1312 */ 1313 if ((scn_str = elf_getscn(elf, shdr_sym.sh_link)) == NULL || 1314 gelf_getshdr(scn_str, &shdr_str) == NULL || 1315 (data_str = elf_getdata(scn_str, NULL)) == NULL) 1316 goto err; 1317 1318 /* 1319 * Grab the section, section header and section data for the 1320 * target section for the relocations. For the relocations 1321 * we're looking for -- this will typically be the text of the 1322 * object file. 1323 */ 1324 if ((scn_tgt = elf_getscn(elf, shdr_rel.sh_info)) == NULL || 1325 gelf_getshdr(scn_tgt, &shdr_tgt) == NULL || 1326 (data_tgt = elf_getdata(scn_tgt, NULL)) == NULL) 1327 goto err; 1328 1329 /* 1330 * We're looking for relocations to symbols matching this form: 1331 * 1332 * __dtrace[enabled]_<prov>___<probe> 1333 * 1334 * For the generated object, we need to record the location 1335 * identified by the relocation, and create a new relocation 1336 * in the generated object that will be resolved at link time 1337 * to the location of the function in which the probe is 1338 * embedded. In the target object, we change the matched symbol 1339 * so that it will be ignored at link time, and we modify the 1340 * target (text) section to replace the call instruction with 1341 * one or more nops. 1342 * 1343 * If the function containing the probe is locally scoped 1344 * (static), we create an alias used by the relocation in the 1345 * generated object. The alias, a new symbol, will be global 1346 * (so that the relocation from the generated object can be 1347 * resolved), and hidden (so that it is converted to a local 1348 * symbol at link time). Such aliases have this form: 1349 * 1350 * $dtrace<key>.<function> 1351 * 1352 * We take a first pass through all the relocations to 1353 * populate our string table and count the number of extra 1354 * symbols we'll require. 1355 */ 1356 strtab = dt_strtab_create(1); 1357 nsym = 0; 1358 isym = data_sym->d_size / symsize; 1359 istr = data_str->d_size; 1360 1361 for (i = 0; i < shdr_rel.sh_size / shdr_rel.sh_entsize; i++) { 1362 1363 if (shdr_rel.sh_type == SHT_RELA) { 1364 if (gelf_getrela(data_rel, i, &rela) == NULL) 1365 continue; 1366 } else { 1367 GElf_Rel rel; 1368 if (gelf_getrel(data_rel, i, &rel) == NULL) 1369 continue; 1370 rela.r_offset = rel.r_offset; 1371 rela.r_info = rel.r_info; 1372 rela.r_addend = 0; 1373 } 1374 1375 if (gelf_getsym(data_sym, GELF_R_SYM(rela.r_info), 1376 &rsym) == NULL) { 1377 dt_strtab_destroy(strtab); 1378 goto err; 1379 } 1380 1381 s = (char *)data_str->d_buf + rsym.st_name; 1382 1383 if (strncmp(s, dt_prefix, sizeof (dt_prefix) - 1) != 0) 1384 continue; 1385 1386 if (dt_symtab_lookup(data_sym, isym, rela.r_offset, 1387 shdr_rel.sh_info, &fsym) != 0) { 1388 dt_strtab_destroy(strtab); 1389 goto err; 1390 } 1391 1392 if (GELF_ST_BIND(fsym.st_info) != STB_LOCAL) 1393 continue; 1394 1395 if (fsym.st_name > data_str->d_size) { 1396 dt_strtab_destroy(strtab); 1397 goto err; 1398 } 1399 1400 s = (char *)data_str->d_buf + fsym.st_name; 1401 1402 /* 1403 * If this symbol isn't of type function, we've really 1404 * driven off the rails or the object file is corrupt. 1405 */ 1406 if (GELF_ST_TYPE(fsym.st_info) != STT_FUNC) { 1407 dt_strtab_destroy(strtab); 1408 return (dt_link_error(dtp, elf, fd, bufs, 1409 "expected %s to be of type function", s)); 1410 } 1411 1412 len = snprintf(NULL, 0, dt_symfmt, dt_symprefix, 1413 objkey, s) + 1; 1414 if ((p = dt_alloc(dtp, len)) == NULL) { 1415 dt_strtab_destroy(strtab); 1416 goto err; 1417 } 1418 (void) snprintf(p, len, dt_symfmt, dt_symprefix, 1419 objkey, s); 1420 1421 if (dt_strtab_index(strtab, p) == -1) { 1422 nsym++; 1423 (void) dt_strtab_insert(strtab, p); 1424 } 1425 1426 dt_free(dtp, p); 1427 } 1428 1429 /* 1430 * If needed, allocate the additional space for the symbol 1431 * table and string table copying the old data into the new 1432 * buffers, and marking the buffers as dirty. We inject those 1433 * newly allocated buffers into the libelf data structures, but 1434 * are still responsible for freeing them once we're done with 1435 * the elf handle. 1436 */ 1437 if (nsym > 0) { 1438 /* 1439 * The first byte of the string table is reserved for 1440 * the \0 entry. 1441 */ 1442 len = dt_strtab_size(strtab) - 1; 1443 1444 assert(len > 0); 1445 assert(dt_strtab_index(strtab, "") == 0); 1446 1447 dt_strtab_destroy(strtab); 1448 1449 if ((pair = dt_alloc(dtp, sizeof (*pair))) == NULL) 1450 goto err; 1451 1452 if ((pair->dlp_str = dt_alloc(dtp, data_str->d_size + 1453 len)) == NULL) { 1454 dt_free(dtp, pair); 1455 goto err; 1456 } 1457 1458 if ((pair->dlp_sym = dt_alloc(dtp, data_sym->d_size + 1459 nsym * symsize)) == NULL) { 1460 dt_free(dtp, pair->dlp_str); 1461 dt_free(dtp, pair); 1462 goto err; 1463 } 1464 1465 pair->dlp_next = bufs; 1466 bufs = pair; 1467 1468 bcopy(data_str->d_buf, pair->dlp_str, data_str->d_size); 1469 data_str->d_buf = pair->dlp_str; 1470 data_str->d_size += len; 1471 (void) elf_flagdata(data_str, ELF_C_SET, ELF_F_DIRTY); 1472 1473 shdr_str.sh_size += len; 1474 (void) gelf_update_shdr(scn_str, &shdr_str); 1475 1476 bcopy(data_sym->d_buf, pair->dlp_sym, data_sym->d_size); 1477 data_sym->d_buf = pair->dlp_sym; 1478 data_sym->d_size += nsym * symsize; 1479 (void) elf_flagdata(data_sym, ELF_C_SET, ELF_F_DIRTY); 1480 1481 shdr_sym.sh_size += nsym * symsize; 1482 (void) gelf_update_shdr(scn_sym, &shdr_sym); 1483 1484 nsym += isym; 1485 } else { 1486 dt_strtab_destroy(strtab); 1487 } 1488 1489 /* 1490 * Now that the tables have been allocated, perform the 1491 * modifications described above. 1492 */ 1493 for (i = 0; i < shdr_rel.sh_size / shdr_rel.sh_entsize; i++) { 1494 1495 if (shdr_rel.sh_type == SHT_RELA) { 1496 if (gelf_getrela(data_rel, i, &rela) == NULL) 1497 continue; 1498 } else { 1499 GElf_Rel rel; 1500 if (gelf_getrel(data_rel, i, &rel) == NULL) 1501 continue; 1502 rela.r_offset = rel.r_offset; 1503 rela.r_info = rel.r_info; 1504 rela.r_addend = 0; 1505 } 1506 1507 ndx = GELF_R_SYM(rela.r_info); 1508 1509 if (gelf_getsym(data_sym, ndx, &rsym) == NULL || 1510 rsym.st_name > data_str->d_size) 1511 goto err; 1512 1513 s = (char *)data_str->d_buf + rsym.st_name; 1514 1515 if (strncmp(s, dt_prefix, sizeof (dt_prefix) - 1) != 0) 1516 continue; 1517 1518 s += sizeof (dt_prefix) - 1; 1519 1520 /* 1521 * Check to see if this is an 'is-enabled' check as 1522 * opposed to a normal probe. 1523 */ 1524 if (strncmp(s, dt_enabled, 1525 sizeof (dt_enabled) - 1) == 0) { 1526 s += sizeof (dt_enabled) - 1; 1527 eprobe = 1; 1528 *eprobesp = 1; 1529 dt_dprintf("is-enabled probe\n"); 1530 } else { 1531 eprobe = 0; 1532 dt_dprintf("normal probe\n"); 1533 } 1534 1535 if (*s++ != '_') 1536 goto err; 1537 1538 if ((p = strstr(s, "___")) == NULL || 1539 p - s >= sizeof (pname)) 1540 goto err; 1541 1542 bcopy(s, pname, p - s); 1543 pname[p - s] = '\0'; 1544 1545 p = strhyphenate(p + 3); /* strlen("___") */ 1546 1547 if (dt_symtab_lookup(data_sym, isym, rela.r_offset, 1548 shdr_rel.sh_info, &fsym) != 0) 1549 goto err; 1550 1551 if (fsym.st_name > data_str->d_size) 1552 goto err; 1553 1554 assert(GELF_ST_TYPE(fsym.st_info) == STT_FUNC); 1555 1556 /* 1557 * If a NULL relocation name is passed to 1558 * dt_probe_define(), the function name is used for the 1559 * relocation. The relocation needs to use a mangled 1560 * name if the symbol is locally scoped; the function 1561 * name may need to change if we've found the global 1562 * alias for the locally scoped symbol (we prefer 1563 * global symbols to locals in dt_symtab_lookup()). 1564 */ 1565 s = (char *)data_str->d_buf + fsym.st_name; 1566 r = NULL; 1567 1568 if (GELF_ST_BIND(fsym.st_info) == STB_LOCAL) { 1569 dsym = fsym; 1570 dsym.st_name = istr; 1571 dsym.st_info = GELF_ST_INFO(STB_GLOBAL, 1572 STT_FUNC); 1573 dsym.st_other = 1574 ELF64_ST_VISIBILITY(STV_ELIMINATE); 1575 (void) gelf_update_sym(data_sym, isym, &dsym); 1576 1577 r = (char *)data_str->d_buf + istr; 1578 istr += 1 + sprintf(r, dt_symfmt, 1579 dt_symprefix, objkey, s); 1580 isym++; 1581 assert(isym <= nsym); 1582 1583 } else if (strncmp(s, dt_symprefix, 1584 strlen(dt_symprefix)) == 0) { 1585 r = s; 1586 if ((s = strchr(s, '.')) == NULL) 1587 goto err; 1588 s++; 1589 } 1590 1591 if ((pvp = dt_provider_lookup(dtp, pname)) == NULL) { 1592 return (dt_link_error(dtp, elf, fd, bufs, 1593 "no such provider %s", pname)); 1594 } 1595 1596 if ((prp = dt_probe_lookup(pvp, p)) == NULL) { 1597 return (dt_link_error(dtp, elf, fd, bufs, 1598 "no such probe %s", p)); 1599 } 1600 1601 assert(fsym.st_value <= rela.r_offset); 1602 1603 off = rela.r_offset - fsym.st_value; 1604 if (dt_modtext(dtp, data_tgt->d_buf, eprobe, 1605 &rela, &off) != 0) 1606 goto err; 1607 1608 if (dt_probe_define(pvp, prp, s, r, off, eprobe) != 0) { 1609 return (dt_link_error(dtp, elf, fd, bufs, 1610 "failed to allocate space for probe")); 1611 } 1612#if !defined(sun) 1613 /* 1614 * Our linker doesn't understand the SUNW_IGNORE ndx and 1615 * will try to use this relocation when we build the 1616 * final executable. Since we are done processing this 1617 * relocation, mark it as inexistant and let libelf 1618 * remove it from the file. 1619 * If this wasn't done, we would have garbage added to 1620 * the executable file as the symbol is going to be 1621 * change from UND to ABS. 1622 */ 1623 rela.r_offset = 0; 1624 rela.r_info = 0; 1625 rela.r_addend = 0; 1626 (void) gelf_update_rela(data_rel, i, &rela); 1627#endif 1628 1629 mod = 1; 1630 (void) elf_flagdata(data_tgt, ELF_C_SET, ELF_F_DIRTY); 1631 1632 /* 1633 * This symbol may already have been marked to 1634 * be ignored by another relocation referencing 1635 * the same symbol or if this object file has 1636 * already been processed by an earlier link 1637 * invocation. 1638 */ 1639#if !defined(sun) 1640#define SHN_SUNW_IGNORE SHN_ABS 1641#endif 1642 if (rsym.st_shndx != SHN_SUNW_IGNORE) { 1643 rsym.st_shndx = SHN_SUNW_IGNORE; 1644 (void) gelf_update_sym(data_sym, ndx, &rsym); 1645 } 1646 } 1647 } 1648 1649 if (mod && elf_update(elf, ELF_C_WRITE) == -1) 1650 goto err; 1651 1652 (void) elf_end(elf); 1653 (void) close(fd); 1654 1655#if !defined(sun) 1656 if (nsym > 0) 1657#endif 1658 while ((pair = bufs) != NULL) { 1659 bufs = pair->dlp_next; 1660 dt_free(dtp, pair->dlp_str); 1661 dt_free(dtp, pair->dlp_sym); 1662 dt_free(dtp, pair); 1663 } 1664 1665 return (0); 1666 1667err: 1668 return (dt_link_error(dtp, elf, fd, bufs, 1669 "an error was encountered while processing %s", obj)); 1670} 1671 1672int 1673dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags, 1674 const char *file, int objc, char *const objv[]) 1675{ 1676#if !defined(sun) 1677 char tfile[PATH_MAX]; 1678 Elf *e; 1679 Elf_Scn *scn; 1680 Elf_Data *data; 1681 GElf_Shdr shdr; 1682 int efd; 1683 size_t stridx; 1684 unsigned char *buf; 1685 char *s; 1686 int loc; 1687 GElf_Ehdr ehdr; 1688 Elf_Scn *scn0; 1689 GElf_Shdr shdr0; 1690 uint64_t off, rc; 1691#endif 1692 char drti[PATH_MAX]; 1693 dof_hdr_t *dof; 1694 int fd, status, i, cur; 1695 char *cmd, tmp; 1696 size_t len; 1697 int eprobes = 0, ret = 0; 1698 1699#if !defined(sun) 1700 if (access(file, R_OK) == 0) { 1701 fprintf(stderr, "dtrace: target object (%s) already exists. " 1702 "Please remove the target\ndtrace: object and rebuild all " 1703 "the source objects if you wish to run the DTrace\n" 1704 "dtrace: linking process again\n", file); 1705 /* 1706 * Several build infrastructures run DTrace twice (e.g. 1707 * postgres) and we don't want the build to fail. Return 1708 * 0 here since this isn't really a fatal error. 1709 */ 1710 return (0); 1711 } 1712 /* XXX Should get a temp file name here. */ 1713 snprintf(tfile, sizeof(tfile), "%s.tmp", file); 1714#endif 1715 1716 /* 1717 * A NULL program indicates a special use in which we just link 1718 * together a bunch of object files specified in objv and then 1719 * unlink(2) those object files. 1720 */ 1721 if (pgp == NULL) { 1722 const char *fmt = "%s -o %s -r"; 1723 1724 len = snprintf(&tmp, 1, fmt, dtp->dt_ld_path, file) + 1; 1725 1726 for (i = 0; i < objc; i++) 1727 len += strlen(objv[i]) + 1; 1728 1729 cmd = alloca(len); 1730 1731 cur = snprintf(cmd, len, fmt, dtp->dt_ld_path, file); 1732 1733 for (i = 0; i < objc; i++) 1734 cur += snprintf(cmd + cur, len - cur, " %s", objv[i]); 1735 1736 if ((status = system(cmd)) == -1) { 1737 return (dt_link_error(dtp, NULL, -1, NULL, 1738 "failed to run %s: %s", dtp->dt_ld_path, 1739 strerror(errno))); 1740 } 1741 1742 if (WIFSIGNALED(status)) { 1743 return (dt_link_error(dtp, NULL, -1, NULL, 1744 "failed to link %s: %s failed due to signal %d", 1745 file, dtp->dt_ld_path, WTERMSIG(status))); 1746 } 1747 1748 if (WEXITSTATUS(status) != 0) { 1749 return (dt_link_error(dtp, NULL, -1, NULL, 1750 "failed to link %s: %s exited with status %d\n", 1751 file, dtp->dt_ld_path, WEXITSTATUS(status))); 1752 } 1753 1754 for (i = 0; i < objc; i++) { 1755 if (strcmp(objv[i], file) != 0) 1756 (void) unlink(objv[i]); 1757 } 1758 1759 return (0); 1760 } 1761 1762 for (i = 0; i < objc; i++) { 1763 if (process_obj(dtp, objv[i], &eprobes) != 0) 1764 return (-1); /* errno is set for us */ 1765 } 1766 1767 /* 1768 * If there are is-enabled probes then we need to force use of DOF 1769 * version 2. 1770 */ 1771 if (eprobes && pgp->dp_dofversion < DOF_VERSION_2) 1772 pgp->dp_dofversion = DOF_VERSION_2; 1773 1774 if ((dof = dtrace_dof_create(dtp, pgp, dflags)) == NULL) 1775 return (-1); /* errno is set for us */ 1776 1777#if defined(sun) 1778 /* 1779 * Create a temporary file and then unlink it if we're going to 1780 * combine it with drti.o later. We can still refer to it in child 1781 * processes as /dev/fd/<fd>. 1782 */ 1783 if ((fd = open64(file, O_RDWR | O_CREAT | O_TRUNC, 0666)) == -1) { 1784 return (dt_link_error(dtp, NULL, -1, NULL, 1785 "failed to open %s: %s", file, strerror(errno))); 1786 } 1787#else 1788 if ((fd = open(tfile, O_RDWR | O_CREAT | O_TRUNC, 0666)) == -1) 1789 return (dt_link_error(dtp, NULL, -1, NULL, 1790 "failed to open %s: %s", tfile, strerror(errno))); 1791#endif 1792 1793 /* 1794 * If -xlinktype=DOF has been selected, just write out the DOF. 1795 * Otherwise proceed to the default of generating and linking ELF. 1796 */ 1797 switch (dtp->dt_linktype) { 1798 case DT_LTYP_DOF: 1799 if (dt_write(dtp, fd, dof, dof->dofh_filesz) < dof->dofh_filesz) 1800 ret = errno; 1801 1802 if (close(fd) != 0 && ret == 0) 1803 ret = errno; 1804 1805 if (ret != 0) { 1806 return (dt_link_error(dtp, NULL, -1, NULL, 1807 "failed to write %s: %s", file, strerror(ret))); 1808 } 1809 1810 return (0); 1811 1812 case DT_LTYP_ELF: 1813 break; /* fall through to the rest of dtrace_program_link() */ 1814 1815 default: 1816 return (dt_link_error(dtp, NULL, -1, NULL, 1817 "invalid link type %u\n", dtp->dt_linktype)); 1818 } 1819 1820 1821#if defined(sun) 1822 if (!dtp->dt_lazyload) 1823 (void) unlink(file); 1824#endif 1825 1826#if defined(sun) 1827 if (dtp->dt_oflags & DTRACE_O_LP64) 1828 status = dump_elf64(dtp, dof, fd); 1829 else 1830 status = dump_elf32(dtp, dof, fd); 1831 1832 if (status != 0 || lseek(fd, 0, SEEK_SET) != 0) { 1833#else 1834 /* We don't write the ELF header, just the DOF section */ 1835 if (dt_write(dtp, fd, dof, dof->dofh_filesz) < dof->dofh_filesz) { 1836#endif 1837 return (dt_link_error(dtp, NULL, -1, NULL, 1838 "failed to write %s: %s", file, strerror(errno))); 1839 } 1840 1841 if (!dtp->dt_lazyload) { 1842#if defined(sun) 1843 const char *fmt = "%s -o %s -r -Blocal -Breduce /dev/fd/%d %s"; 1844 1845 if (dtp->dt_oflags & DTRACE_O_LP64) { 1846 (void) snprintf(drti, sizeof (drti), 1847 "%s/64/drti.o", _dtrace_libdir); 1848 } else { 1849 (void) snprintf(drti, sizeof (drti), 1850 "%s/drti.o", _dtrace_libdir); 1851 } 1852 1853 len = snprintf(&tmp, 1, fmt, dtp->dt_ld_path, file, fd, 1854 drti) + 1; 1855 1856 cmd = alloca(len); 1857 1858 (void) snprintf(cmd, len, fmt, dtp->dt_ld_path, file, fd, drti); 1859#else 1860 const char *fmt = "%s -o %s -r %s"; 1861 1862#if defined(__amd64__) 1863 /* 1864 * Arches which default to 64-bit need to explicitly use 1865 * the 32-bit library path. 1866 */ 1867 int use_32 = !(dtp->dt_oflags & DTRACE_O_LP64); 1868#else 1869 /* 1870 * Arches which are 32-bit only just use the normal 1871 * library path. 1872 */ 1873 int use_32 = 0; 1874#endif 1875 1876 (void) snprintf(drti, sizeof (drti), "/usr/lib%s/dtrace/drti.o", 1877 use_32 ? "32":""); 1878 1879 len = snprintf(&tmp, 1, fmt, dtp->dt_ld_path, file, tfile, 1880 drti) + 1; 1881 1882#if !defined(sun) 1883 len *= 2; 1884#endif 1885 cmd = alloca(len); 1886 1887 (void) snprintf(cmd, len, fmt, dtp->dt_ld_path, file, 1888 drti); 1889#endif 1890 if ((status = system(cmd)) == -1) { 1891 ret = dt_link_error(dtp, NULL, -1, NULL, 1892 "failed to run %s: %s", dtp->dt_ld_path, 1893 strerror(errno)); 1894 goto done; 1895 } 1896 1897 if (WIFSIGNALED(status)) { 1898 ret = dt_link_error(dtp, NULL, -1, NULL, 1899 "failed to link %s: %s failed due to signal %d", 1900 file, dtp->dt_ld_path, WTERMSIG(status)); 1901 goto done; 1902 } 1903 1904 if (WEXITSTATUS(status) != 0) { 1905 ret = dt_link_error(dtp, NULL, -1, NULL, 1906 "failed to link %s: %s exited with status %d\n", 1907 file, dtp->dt_ld_path, WEXITSTATUS(status)); 1908 goto done; 1909 } 1910#if !defined(sun) 1911#define BROKEN_LIBELF 1912 /* 1913 * FreeBSD's ld(1) is not instructed to interpret and add 1914 * correctly the SUNW_dof section present in tfile. 1915 * We use libelf to add this section manually and hope the next 1916 * ld invocation won't remove it. 1917 */ 1918 elf_version(EV_CURRENT); 1919 if ((efd = open(file, O_RDWR, 0)) < 0) { 1920 ret = dt_link_error(dtp, NULL, -1, NULL, 1921 "failed to open file %s: %s", 1922 file, strerror(errno)); 1923 goto done; 1924 } 1925 if ((e = elf_begin(efd, ELF_C_RDWR, NULL)) == NULL) { 1926 close(efd); 1927 ret = dt_link_error(dtp, NULL, -1, NULL, 1928 "failed to open elf file: %s", 1929 elf_errmsg(elf_errno())); 1930 goto done; 1931 } 1932 /* 1933 * Add the string '.SUWN_dof' to the shstrtab section. 1934 */ 1935#ifdef BROKEN_LIBELF 1936 elf_flagelf(e, ELF_C_SET, ELF_F_LAYOUT); 1937#endif 1938 elf_getshdrstrndx(e, &stridx); 1939 scn = elf_getscn(e, stridx); 1940 gelf_getshdr(scn, &shdr); 1941 data = elf_newdata(scn); 1942 data->d_off = shdr.sh_size; 1943 data->d_buf = ".SUNW_dof"; 1944 data->d_size = 10; 1945 data->d_type = ELF_T_BYTE; 1946 loc = shdr.sh_size; 1947 shdr.sh_size += data->d_size; 1948 gelf_update_shdr(scn, &shdr); 1949#ifdef BROKEN_LIBELF 1950 off = shdr.sh_offset; 1951 rc = shdr.sh_offset + shdr.sh_size; 1952 gelf_getehdr(e, &ehdr); 1953 if (ehdr.e_shoff > off) { 1954 off = ehdr.e_shoff + ehdr.e_shnum * ehdr.e_shentsize; 1955 rc = roundup(rc, 8); 1956 ehdr.e_shoff = rc; 1957 gelf_update_ehdr(e, &ehdr); 1958 rc += ehdr.e_shnum * ehdr.e_shentsize; 1959 } 1960 for (;;) { 1961 scn0 = NULL; 1962 scn = NULL; 1963 while ((scn = elf_nextscn(e, scn)) != NULL) { 1964 gelf_getshdr(scn, &shdr); 1965 if (shdr.sh_type == SHT_NOBITS || 1966 shdr.sh_offset < off) 1967 continue; 1968 /* Find the immediately adjcent section. */ 1969 if (scn0 == NULL || 1970 shdr.sh_offset < shdr0.sh_offset) { 1971 scn0 = scn; 1972 gelf_getshdr(scn0, &shdr0); 1973 } 1974 } 1975 if (scn0 == NULL) 1976 break; 1977 /* Load section data to work around another bug */ 1978 elf_getdata(scn0, NULL); 1979 /* Update section header, assure section alignment */ 1980 off = shdr0.sh_offset + shdr0.sh_size; 1981 rc = roundup(rc, shdr0.sh_addralign); 1982 shdr0.sh_offset = rc; 1983 gelf_update_shdr(scn0, &shdr0); 1984 rc += shdr0.sh_size; 1985 } 1986 if (elf_update(e, ELF_C_WRITE) < 0) { 1987 ret = dt_link_error(dtp, NULL, -1, NULL, 1988 "failed to add append the shstrtab section: %s", 1989 elf_errmsg(elf_errno())); 1990 elf_end(e); 1991 close(efd); 1992 goto done; 1993 } 1994 elf_end(e); 1995 e = elf_begin(efd, ELF_C_RDWR, NULL); 1996#endif 1997 /* 1998 * Construct the .SUNW_dof section. 1999 */ 2000 scn = elf_newscn(e); 2001 data = elf_newdata(scn); 2002 buf = mmap(NULL, dof->dofh_filesz, PROT_READ, MAP_SHARED, 2003 fd, 0); 2004 if (buf == MAP_FAILED) { 2005 ret = dt_link_error(dtp, NULL, -1, NULL, 2006 "failed to mmap buffer %s", strerror(errno)); 2007 elf_end(e); 2008 close(efd); 2009 goto done; 2010 } 2011 data->d_buf = buf; 2012 data->d_align = 4; 2013 data->d_size = dof->dofh_filesz; 2014 data->d_version = EV_CURRENT; 2015 gelf_getshdr(scn, &shdr); 2016 shdr.sh_name = loc; 2017 shdr.sh_flags = SHF_ALLOC; 2018 /* 2019 * Actually this should be SHT_SUNW_dof, but FreeBSD's ld(1) 2020 * will remove this 'unknown' section when we try to create an 2021 * executable using the object we are modifying, so we stop 2022 * playing by the rules and use SHT_PROGBITS. 2023 * Also, note that our drti has modifications to handle this. 2024 */ 2025 shdr.sh_type = SHT_PROGBITS; 2026 shdr.sh_addralign = 4; 2027 gelf_update_shdr(scn, &shdr); 2028 if (elf_update(e, ELF_C_WRITE) < 0) { 2029 ret = dt_link_error(dtp, NULL, -1, NULL, 2030 "failed to add the SUNW_dof section: %s", 2031 elf_errmsg(elf_errno())); 2032 munmap(buf, dof->dofh_filesz); 2033 elf_end(e); 2034 close(efd); 2035 goto done; 2036 } 2037 munmap(buf, dof->dofh_filesz); 2038 elf_end(e); 2039 close(efd); 2040#endif 2041 (void) close(fd); /* release temporary file */ 2042 } else { 2043 (void) close(fd); 2044 } 2045 2046done: 2047 dtrace_dof_destroy(dtp, dof); 2048 2049#if !defined(sun) 2050 unlink(tfile); 2051#endif 2052 return (ret); 2053} 2054