1 /* 2 * Copyright (c) 2003, 2009, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, 20 * CA 94065 USA or visit www.oracle.com if you need additional information or 21 * have any questions. 22 * 23 */ 24 25 #include <jni.h> 26 #include <unistd.h> 27 #include <fcntl.h> 28 #include <string.h> 29 #include <stdlib.h> 30 #include <stddef.h> 31 #include <elf.h> 32 #include <link.h> 33 #include "libproc_impl.h" 34 #include "salibelf.h" 35 36 // This file has the libproc implementation to read core files. 37 // For live processes, refer to ps_proc.c. Portions of this is adapted 38 // /modelled after Solaris libproc.so (in particular Pcore.c) 39 40 //---------------------------------------------------------------------- 41 // ps_prochandle cleanup helper functions 42 43 // close all file descriptors 44 static void close_elf_files(struct ps_prochandle* ph) { 45 lib_info* lib = NULL; 46 47 // close core file descriptor 48 if (ph->core->core_fd >= 0) 49 close(ph->core->core_fd); 50 51 // close exec file descriptor 52 if (ph->core->exec_fd >= 0) 53 close(ph->core->exec_fd); 54 55 // close interp file descriptor 56 if (ph->core->interp_fd >= 0) 57 close(ph->core->interp_fd); 58 59 // close class share archive file 60 if (ph->core->classes_jsa_fd >= 0) 61 close(ph->core->classes_jsa_fd); 62 63 // close all library file descriptors 64 lib = ph->libs; 65 while (lib) { 66 int fd = lib->fd; 67 if (fd >= 0 && fd != ph->core->exec_fd) close(fd); 68 lib = lib->next; 69 } 70 } 71 72 // clean all map_info stuff 73 static void destroy_map_info(struct ps_prochandle* ph) { 74 map_info* map = ph->core->maps; 75 while (map) { 76 map_info* next = map->next; 77 free(map); 78 map = next; 79 } 80 81 if (ph->core->map_array) { 82 free(ph->core->map_array); 83 } 84 85 // Part of the class sharing workaround 86 map = ph->core->class_share_maps; 87 while (map) { 88 map_info* next = map->next; 89 free(map); 90 map = next; 91 } 92 } 93 94 // ps_prochandle operations 95 static void core_release(struct ps_prochandle* ph) { 96 if (ph->core) { 97 close_elf_files(ph); 98 destroy_map_info(ph); 99 free(ph->core); 100 } 101 } 102 103 static map_info* allocate_init_map(int fd, off_t offset, uintptr_t vaddr, size_t memsz) { 104 map_info* map; 105 if ( (map = (map_info*) calloc(1, sizeof(map_info))) == NULL) { 106 print_debug("can't allocate memory for map_info\n"); 107 return NULL; 108 } 109 110 // initialize map 111 map->fd = fd; 112 map->offset = offset; 113 map->vaddr = vaddr; 114 map->memsz = memsz; 115 return map; 116 } 117 118 // add map info with given fd, offset, vaddr and memsz 119 static map_info* add_map_info(struct ps_prochandle* ph, int fd, off_t offset, 120 uintptr_t vaddr, size_t memsz) { 121 map_info* map; 122 if ((map = allocate_init_map(fd, offset, vaddr, memsz)) == NULL) { 123 return NULL; 124 } 125 126 // add this to map list 127 map->next = ph->core->maps; 128 ph->core->maps = map; 129 ph->core->num_maps++; 130 131 return map; 132 } 133 134 // Part of the class sharing workaround 135 static map_info* add_class_share_map_info(struct ps_prochandle* ph, off_t offset, 136 uintptr_t vaddr, size_t memsz) { 137 map_info* map; 138 if ((map = allocate_init_map(ph->core->classes_jsa_fd, 139 offset, vaddr, memsz)) == NULL) { 140 return NULL; 141 } 142 143 map->next = ph->core->class_share_maps; 144 ph->core->class_share_maps = map; 145 } 146 147 // Return the map_info for the given virtual address. We keep a sorted 148 // array of pointers in ph->map_array, so we can binary search. 149 static map_info* core_lookup(struct ps_prochandle *ph, uintptr_t addr) 150 { 151 int mid, lo = 0, hi = ph->core->num_maps - 1; 152 map_info *mp; 153 154 while (hi - lo > 1) { 155 mid = (lo + hi) / 2; 156 if (addr >= ph->core->map_array[mid]->vaddr) 157 lo = mid; 158 else 159 hi = mid; 160 } 161 162 if (addr < ph->core->map_array[hi]->vaddr) 163 mp = ph->core->map_array[lo]; 164 else 165 mp = ph->core->map_array[hi]; 166 167 if (addr >= mp->vaddr && addr < mp->vaddr + mp->memsz) 168 return (mp); 169 170 171 // Part of the class sharing workaround 172 // Unfortunately, we have no way of detecting -Xshare state. 173 // Check out the share maps atlast, if we don't find anywhere. 174 // This is done this way so to avoid reading share pages 175 // ahead of other normal maps. For eg. with -Xshare:off we don't 176 // want to prefer class sharing data to data from core. 177 mp = ph->core->class_share_maps; 178 if (mp) { 179 print_debug("can't locate map_info at 0x%lx, trying class share maps\n", 180 addr); 181 } 182 while (mp) { 183 if (addr >= mp->vaddr && addr < mp->vaddr + mp->memsz) { 184 print_debug("located map_info at 0x%lx from class share maps\n", 185 addr); 186 return (mp); 187 } 188 mp = mp->next; 189 } 190 191 print_debug("can't locate map_info at 0x%lx\n", addr); 192 return (NULL); 193 } 194 195 //--------------------------------------------------------------- 196 // Part of the class sharing workaround: 197 // 198 // With class sharing, pages are mapped from classes[_g].jsa file. 199 // The read-only class sharing pages are mapped as MAP_SHARED, 200 // PROT_READ pages. These pages are not dumped into core dump. 201 // With this workaround, these pages are read from classes[_g].jsa. 202 203 // FIXME: !HACK ALERT! 204 // The format of sharing achive file header is needed to read shared heap 205 // file mappings. For now, I am hard coding portion of FileMapHeader here. 206 // Refer to filemap.hpp. 207 208 // FileMapHeader describes the shared space data in the file to be 209 // mapped. This structure gets written to a file. It is not a class, 210 // so that the compilers don't add any compiler-private data to it. 211 212 // Refer to CompactingPermGenGen::n_regions in compactingPermGenGen.hpp 213 #define NUM_SHARED_MAPS 4 214 215 // Refer to FileMapInfo::_current_version in filemap.hpp 216 #define CURRENT_ARCHIVE_VERSION 1 217 218 struct FileMapHeader { 219 int _magic; // identify file type. 220 int _version; // (from enum, above.) 221 size_t _alignment; // how shared archive should be aligned 222 223 struct space_info { 224 int _file_offset; // sizeof(this) rounded to vm page size 225 char* _base; // copy-on-write base address 226 size_t _capacity; // for validity checking 227 size_t _used; // for setting space top on read 228 229 // 4991491 NOTICE These are C++ bool's in filemap.hpp and must match up with 230 // the C type matching the C++ bool type on any given platform. For 231 // Hotspot on Linux we assume the corresponding C type is char but 232 // licensees on Linux versions may need to adjust the type of these fields. 233 char _read_only; // read only space? 234 char _allow_exec; // executable code in space? 235 236 } _space[NUM_SHARED_MAPS]; // was _space[CompactingPermGenGen::n_regions]; 237 238 // Ignore the rest of the FileMapHeader. We don't need those fields here. 239 }; 240 241 static bool read_jboolean(struct ps_prochandle* ph, uintptr_t addr, jboolean* pvalue) { 242 jboolean i; 243 if (ps_pdread(ph, (psaddr_t) addr, &i, sizeof(i)) == PS_OK) { 244 *pvalue = i; 245 return true; 246 } else { 247 return false; 248 } 249 } 250 251 static bool read_pointer(struct ps_prochandle* ph, uintptr_t addr, uintptr_t* pvalue) { 252 uintptr_t uip; 253 if (ps_pdread(ph, (psaddr_t) addr, &uip, sizeof(uip)) == PS_OK) { 254 *pvalue = uip; 255 return true; 256 } else { 257 return false; 258 } 259 } 260 261 // used to read strings from debuggee 262 static bool read_string(struct ps_prochandle* ph, uintptr_t addr, char* buf, size_t size) { 263 size_t i = 0; 264 char c = ' '; 265 266 while (c != '\0') { 267 if (ps_pdread(ph, (psaddr_t) addr, &c, sizeof(char)) != PS_OK) 268 return false; 269 if (i < size - 1) 270 buf[i] = c; 271 else // smaller buffer 272 return false; 273 i++; addr++; 274 } 275 276 buf[i] = '\0'; 277 return true; 278 } 279 280 #define USE_SHARED_SPACES_SYM "UseSharedSpaces" 281 // mangled name of Arguments::SharedArchivePath 282 #define SHARED_ARCHIVE_PATH_SYM "_ZN9Arguments17SharedArchivePathE" 283 284 static bool init_classsharing_workaround(struct ps_prochandle* ph) { 285 lib_info* lib = ph->libs; 286 while (lib != NULL) { 287 // we are iterating over shared objects from the core dump. look for 288 // libjvm[_g].so. 289 const char *jvm_name = 0; 290 if ((jvm_name = strstr(lib->name, "/libjvm.so")) != 0 || 291 (jvm_name = strstr(lib->name, "/libjvm_g.so")) != 0) { 292 char classes_jsa[PATH_MAX]; 293 struct FileMapHeader header; 294 size_t n = 0; 295 int fd = -1, m = 0; 296 uintptr_t base = 0, useSharedSpacesAddr = 0; 297 uintptr_t sharedArchivePathAddrAddr = 0, sharedArchivePathAddr = 0; 298 jboolean useSharedSpaces = 0; 299 map_info* mi = 0; 300 301 memset(classes_jsa, 0, sizeof(classes_jsa)); 302 jvm_name = lib->name; 303 useSharedSpacesAddr = lookup_symbol(ph, jvm_name, USE_SHARED_SPACES_SYM); 304 if (useSharedSpacesAddr == 0) { 305 print_debug("can't lookup 'UseSharedSpaces' flag\n"); 306 return false; 307 } 308 309 // Hotspot vm types are not exported to build this library. So 310 // using equivalent type jboolean to read the value of 311 // UseSharedSpaces which is same as hotspot type "bool". 312 if (read_jboolean(ph, useSharedSpacesAddr, &useSharedSpaces) != true) { 313 print_debug("can't read the value of 'UseSharedSpaces' flag\n"); 314 return false; 315 } 316 317 if ((int)useSharedSpaces == 0) { 318 print_debug("UseSharedSpaces is false, assuming -Xshare:off!\n"); 319 return true; 320 } 321 322 sharedArchivePathAddrAddr = lookup_symbol(ph, jvm_name, SHARED_ARCHIVE_PATH_SYM); 323 if (sharedArchivePathAddrAddr == 0) { 324 print_debug("can't lookup shared archive path symbol\n"); 325 return false; 326 } 327 328 if (read_pointer(ph, sharedArchivePathAddrAddr, &sharedArchivePathAddr) != true) { 329 print_debug("can't read shared archive path pointer\n"); 330 return false; 331 } 332 333 if (read_string(ph, sharedArchivePathAddr, classes_jsa, sizeof(classes_jsa)) != true) { 334 print_debug("can't read shared archive path value\n"); 335 return false; 336 } 337 338 print_debug("looking for %s\n", classes_jsa); 339 // open the class sharing archive file 340 fd = pathmap_open(classes_jsa); 341 if (fd < 0) { 342 print_debug("can't open %s!\n", classes_jsa); 343 ph->core->classes_jsa_fd = -1; 344 return false; 345 } else { 346 print_debug("opened %s\n", classes_jsa); 347 } 348 349 // read FileMapHeader from the file 350 memset(&header, 0, sizeof(struct FileMapHeader)); 351 if ((n = read(fd, &header, sizeof(struct FileMapHeader))) 352 != sizeof(struct FileMapHeader)) { 353 print_debug("can't read shared archive file map header from %s\n", classes_jsa); 354 close(fd); 355 return false; 356 } 357 358 // check file magic 359 if (header._magic != 0xf00baba2) { 360 print_debug("%s has bad shared archive file magic number 0x%x, expecing 0xf00baba2\n", 361 classes_jsa, header._magic); 362 close(fd); 363 return false; 364 } 365 366 // check version 367 if (header._version != CURRENT_ARCHIVE_VERSION) { 368 print_debug("%s has wrong shared archive file version %d, expecting %d\n", 369 classes_jsa, header._version, CURRENT_ARCHIVE_VERSION); 370 close(fd); 371 return false; 372 } 373 374 ph->core->classes_jsa_fd = fd; 375 // add read-only maps from classes[_g].jsa to the list of maps 376 for (m = 0; m < NUM_SHARED_MAPS; m++) { 377 if (header._space[m]._read_only) { 378 base = (uintptr_t) header._space[m]._base; 379 // no need to worry about the fractional pages at-the-end. 380 // possible fractional pages are handled by core_read_data. 381 add_class_share_map_info(ph, (off_t) header._space[m]._file_offset, 382 base, (size_t) header._space[m]._used); 383 print_debug("added a share archive map at 0x%lx\n", base); 384 } 385 } 386 return true; 387 } 388 lib = lib->next; 389 } 390 return true; 391 } 392 393 394 //--------------------------------------------------------------------------- 395 // functions to handle map_info 396 397 // Order mappings based on virtual address. We use this function as the 398 // callback for sorting the array of map_info pointers. 399 static int core_cmp_mapping(const void *lhsp, const void *rhsp) 400 { 401 const map_info *lhs = *((const map_info **)lhsp); 402 const map_info *rhs = *((const map_info **)rhsp); 403 404 if (lhs->vaddr == rhs->vaddr) 405 return (0); 406 407 return (lhs->vaddr < rhs->vaddr ? -1 : 1); 408 } 409 410 // we sort map_info by starting virtual address so that we can do 411 // binary search to read from an address. 412 static bool sort_map_array(struct ps_prochandle* ph) { 413 size_t num_maps = ph->core->num_maps; 414 map_info* map = ph->core->maps; 415 int i = 0; 416 417 // allocate map_array 418 map_info** array; 419 if ( (array = (map_info**) malloc(sizeof(map_info*) * num_maps)) == NULL) { 420 print_debug("can't allocate memory for map array\n"); 421 return false; 422 } 423 424 // add maps to array 425 while (map) { 426 array[i] = map; 427 i++; 428 map = map->next; 429 } 430 431 // sort is called twice. If this is second time, clear map array 432 if (ph->core->map_array) free(ph->core->map_array); 433 ph->core->map_array = array; 434 // sort the map_info array by base virtual address. 435 qsort(ph->core->map_array, ph->core->num_maps, sizeof (map_info*), 436 core_cmp_mapping); 437 438 // print map 439 if (is_debug()) { 440 int j = 0; 441 print_debug("---- sorted virtual address map ----\n"); 442 for (j = 0; j < ph->core->num_maps; j++) { 443 print_debug("base = 0x%lx\tsize = %d\n", ph->core->map_array[j]->vaddr, 444 ph->core->map_array[j]->memsz); 445 } 446 } 447 448 return true; 449 } 450 451 #ifndef MIN 452 #define MIN(x, y) (((x) < (y))? (x): (y)) 453 #endif 454 455 static bool core_read_data(struct ps_prochandle* ph, uintptr_t addr, char *buf, size_t size) { 456 ssize_t resid = size; 457 int page_size=sysconf(_SC_PAGE_SIZE); 458 while (resid != 0) { 459 map_info *mp = core_lookup(ph, addr); 460 uintptr_t mapoff; 461 ssize_t len, rem; 462 off_t off; 463 int fd; 464 465 if (mp == NULL) 466 break; /* No mapping for this address */ 467 468 fd = mp->fd; 469 mapoff = addr - mp->vaddr; 470 len = MIN(resid, mp->memsz - mapoff); 471 off = mp->offset + mapoff; 472 473 if ((len = pread(fd, buf, len, off)) <= 0) 474 break; 475 476 resid -= len; 477 addr += len; 478 buf = (char *)buf + len; 479 480 // mappings always start at page boundary. But, may end in fractional 481 // page. fill zeros for possible fractional page at the end of a mapping. 482 rem = mp->memsz % page_size; 483 if (rem > 0) { 484 rem = page_size - rem; 485 len = MIN(resid, rem); 486 resid -= len; 487 addr += len; 488 // we are not assuming 'buf' to be zero initialized. 489 memset(buf, 0, len); 490 buf += len; 491 } 492 } 493 494 if (resid) { 495 print_debug("core read failed for %d byte(s) @ 0x%lx (%d more bytes)\n", 496 size, addr, resid); 497 return false; 498 } else { 499 return true; 500 } 501 } 502 503 // null implementation for write 504 static bool core_write_data(struct ps_prochandle* ph, 505 uintptr_t addr, const char *buf , size_t size) { 506 return false; 507 } 508 509 static bool core_get_lwp_regs(struct ps_prochandle* ph, lwpid_t lwp_id, 510 struct user_regs_struct* regs) { 511 // for core we have cached the lwp regs from NOTE section 512 thread_info* thr = ph->threads; 513 while (thr) { 514 if (thr->lwp_id == lwp_id) { 515 memcpy(regs, &thr->regs, sizeof(struct user_regs_struct)); 516 return true; 517 } 518 thr = thr->next; 519 } 520 return false; 521 } 522 523 static ps_prochandle_ops core_ops = { 524 .release= core_release, 525 .p_pread= core_read_data, 526 .p_pwrite= core_write_data, 527 .get_lwp_regs= core_get_lwp_regs 528 }; 529 530 // read regs and create thread from NT_PRSTATUS entries from core file 531 static bool core_handle_prstatus(struct ps_prochandle* ph, const char* buf, size_t nbytes) { 532 // we have to read prstatus_t from buf 533 // assert(nbytes == sizeof(prstaus_t), "size mismatch on prstatus_t"); 534 prstatus_t* prstat = (prstatus_t*) buf; 535 thread_info* newthr; 536 print_debug("got integer regset for lwp %d\n", prstat->pr_pid); 537 // we set pthread_t to -1 for core dump 538 if((newthr = add_thread_info(ph, (pthread_t) -1, prstat->pr_pid)) == NULL) 539 return false; 540 541 // copy regs 542 memcpy(&newthr->regs, prstat->pr_reg, sizeof(struct user_regs_struct)); 543 544 if (is_debug()) { 545 print_debug("integer regset\n"); 546 #ifdef i386 547 // print the regset 548 print_debug("\teax = 0x%x\n", newthr->regs.eax); 549 print_debug("\tebx = 0x%x\n", newthr->regs.ebx); 550 print_debug("\tecx = 0x%x\n", newthr->regs.ecx); 551 print_debug("\tedx = 0x%x\n", newthr->regs.edx); 552 print_debug("\tesp = 0x%x\n", newthr->regs.esp); 553 print_debug("\tebp = 0x%x\n", newthr->regs.ebp); 554 print_debug("\tesi = 0x%x\n", newthr->regs.esi); 555 print_debug("\tedi = 0x%x\n", newthr->regs.edi); 556 print_debug("\teip = 0x%x\n", newthr->regs.eip); 557 #endif 558 559 #if defined(amd64) || defined(x86_64) 560 // print the regset 561 print_debug("\tr15 = 0x%lx\n", newthr->regs.r15); 562 print_debug("\tr14 = 0x%lx\n", newthr->regs.r14); 563 print_debug("\tr13 = 0x%lx\n", newthr->regs.r13); 564 print_debug("\tr12 = 0x%lx\n", newthr->regs.r12); 565 print_debug("\trbp = 0x%lx\n", newthr->regs.rbp); 566 print_debug("\trbx = 0x%lx\n", newthr->regs.rbx); 567 print_debug("\tr11 = 0x%lx\n", newthr->regs.r11); 568 print_debug("\tr10 = 0x%lx\n", newthr->regs.r10); 569 print_debug("\tr9 = 0x%lx\n", newthr->regs.r9); 570 print_debug("\tr8 = 0x%lx\n", newthr->regs.r8); 571 print_debug("\trax = 0x%lx\n", newthr->regs.rax); 572 print_debug("\trcx = 0x%lx\n", newthr->regs.rcx); 573 print_debug("\trdx = 0x%lx\n", newthr->regs.rdx); 574 print_debug("\trsi = 0x%lx\n", newthr->regs.rsi); 575 print_debug("\trdi = 0x%lx\n", newthr->regs.rdi); 576 print_debug("\torig_rax = 0x%lx\n", newthr->regs.orig_rax); 577 print_debug("\trip = 0x%lx\n", newthr->regs.rip); 578 print_debug("\tcs = 0x%lx\n", newthr->regs.cs); 579 print_debug("\teflags = 0x%lx\n", newthr->regs.eflags); 580 print_debug("\trsp = 0x%lx\n", newthr->regs.rsp); 581 print_debug("\tss = 0x%lx\n", newthr->regs.ss); 582 print_debug("\tfs_base = 0x%lx\n", newthr->regs.fs_base); 583 print_debug("\tgs_base = 0x%lx\n", newthr->regs.gs_base); 584 print_debug("\tds = 0x%lx\n", newthr->regs.ds); 585 print_debug("\tes = 0x%lx\n", newthr->regs.es); 586 print_debug("\tfs = 0x%lx\n", newthr->regs.fs); 587 print_debug("\tgs = 0x%lx\n", newthr->regs.gs); 588 #endif 589 } 590 591 return true; 592 } 593 594 #define ROUNDUP(x, y) ((((x)+((y)-1))/(y))*(y)) 595 596 // read NT_PRSTATUS entries from core NOTE segment 597 static bool core_handle_note(struct ps_prochandle* ph, ELF_PHDR* note_phdr) { 598 char* buf = NULL; 599 char* p = NULL; 600 size_t size = note_phdr->p_filesz; 601 602 // we are interested in just prstatus entries. we will ignore the rest. 603 // Advance the seek pointer to the start of the PT_NOTE data 604 if (lseek(ph->core->core_fd, note_phdr->p_offset, SEEK_SET) == (off_t)-1) { 605 print_debug("failed to lseek to PT_NOTE data\n"); 606 return false; 607 } 608 609 // Now process the PT_NOTE structures. Each one is preceded by 610 // an Elf{32/64}_Nhdr structure describing its type and size. 611 if ( (buf = (char*) malloc(size)) == NULL) { 612 print_debug("can't allocate memory for reading core notes\n"); 613 goto err; 614 } 615 616 // read notes into buffer 617 if (read(ph->core->core_fd, buf, size) != size) { 618 print_debug("failed to read notes, core file must have been truncated\n"); 619 goto err; 620 } 621 622 p = buf; 623 while (p < buf + size) { 624 ELF_NHDR* notep = (ELF_NHDR*) p; 625 char* descdata = p + sizeof(ELF_NHDR) + ROUNDUP(notep->n_namesz, 4); 626 print_debug("Note header with n_type = %d and n_descsz = %u\n", 627 notep->n_type, notep->n_descsz); 628 629 if (notep->n_type == NT_PRSTATUS) { 630 if (core_handle_prstatus(ph, descdata, notep->n_descsz) != true) 631 return false; 632 } 633 p = descdata + ROUNDUP(notep->n_descsz, 4); 634 } 635 636 free(buf); 637 return true; 638 639 err: 640 if (buf) free(buf); 641 return false; 642 } 643 644 // read all segments from core file 645 static bool read_core_segments(struct ps_prochandle* ph, ELF_EHDR* core_ehdr) { 646 int i = 0; 647 ELF_PHDR* phbuf = NULL; 648 ELF_PHDR* core_php = NULL; 649 650 if ((phbuf = read_program_header_table(ph->core->core_fd, core_ehdr)) == NULL) 651 return false; 652 653 /* 654 * Now iterate through the program headers in the core file. 655 * We're interested in two types of Phdrs: PT_NOTE (which 656 * contains a set of saved /proc structures), and PT_LOAD (which 657 * represents a memory mapping from the process's address space). 658 * 659 * Difference b/w Solaris PT_NOTE and Linux PT_NOTE: 660 * 661 * In Solaris there are two PT_NOTE segments the first PT_NOTE (if present) 662 * contains /proc structs in the pre-2.6 unstructured /proc format. the last 663 * PT_NOTE has data in new /proc format. 664 * 665 * In Solaris, there is only one pstatus (process status). pstatus contains 666 * integer register set among other stuff. For each LWP, we have one lwpstatus 667 * entry that has integer regset for that LWP. 668 * 669 * Linux threads are actually 'clone'd processes. To support core analysis 670 * of "multithreaded" process, Linux creates more than one pstatus (called 671 * "prstatus") entry in PT_NOTE. Each prstatus entry has integer regset for one 672 * "thread". Please refer to Linux kernel src file 'fs/binfmt_elf.c', in particular 673 * function "elf_core_dump". 674 */ 675 676 for (core_php = phbuf, i = 0; i < core_ehdr->e_phnum; i++) { 677 switch (core_php->p_type) { 678 case PT_NOTE: 679 if (core_handle_note(ph, core_php) != true) goto err; 680 break; 681 682 case PT_LOAD: { 683 if (core_php->p_filesz != 0) { 684 if (add_map_info(ph, ph->core->core_fd, core_php->p_offset, 685 core_php->p_vaddr, core_php->p_filesz) == NULL) goto err; 686 } 687 break; 688 } 689 } 690 691 core_php++; 692 } 693 694 free(phbuf); 695 return true; 696 err: 697 free(phbuf); 698 return false; 699 } 700 701 // read segments of a shared object 702 static bool read_lib_segments(struct ps_prochandle* ph, int lib_fd, ELF_EHDR* lib_ehdr, uintptr_t lib_base) { 703 int i = 0; 704 ELF_PHDR* phbuf; 705 ELF_PHDR* lib_php = NULL; 706 707 if ((phbuf = read_program_header_table(lib_fd, lib_ehdr)) == NULL) 708 return false; 709 710 // we want to process only PT_LOAD segments that are not writable. 711 // i.e., text segments. The read/write/exec (data) segments would 712 // have been already added from core file segments. 713 for (lib_php = phbuf, i = 0; i < lib_ehdr->e_phnum; i++) { 714 if ((lib_php->p_type == PT_LOAD) && !(lib_php->p_flags & PF_W) && (lib_php->p_filesz != 0)) { 715 if (add_map_info(ph, lib_fd, lib_php->p_offset, lib_php->p_vaddr + lib_base, lib_php->p_filesz) == NULL) 716 goto err; 717 } 718 lib_php++; 719 } 720 721 free(phbuf); 722 return true; 723 err: 724 free(phbuf); 725 return false; 726 } 727 728 // process segments from interpreter (ld.so or ld-linux.so) 729 static bool read_interp_segments(struct ps_prochandle* ph) { 730 ELF_EHDR interp_ehdr; 731 732 if (read_elf_header(ph->core->interp_fd, &interp_ehdr) != true) { 733 print_debug("interpreter is not a valid ELF file\n"); 734 return false; 735 } 736 737 if (read_lib_segments(ph, ph->core->interp_fd, &interp_ehdr, ph->core->ld_base_addr) != true) { 738 print_debug("can't read segments of interpreter\n"); 739 return false; 740 } 741 742 return true; 743 } 744 745 // process segments of a a.out 746 static bool read_exec_segments(struct ps_prochandle* ph, ELF_EHDR* exec_ehdr) { 747 int i = 0; 748 ELF_PHDR* phbuf = NULL; 749 ELF_PHDR* exec_php = NULL; 750 751 if ((phbuf = read_program_header_table(ph->core->exec_fd, exec_ehdr)) == NULL) 752 return false; 753 754 for (exec_php = phbuf, i = 0; i < exec_ehdr->e_phnum; i++) { 755 switch (exec_php->p_type) { 756 757 // add mappings for PT_LOAD segments 758 case PT_LOAD: { 759 // add only non-writable segments of non-zero filesz 760 if (!(exec_php->p_flags & PF_W) && exec_php->p_filesz != 0) { 761 if (add_map_info(ph, ph->core->exec_fd, exec_php->p_offset, exec_php->p_vaddr, exec_php->p_filesz) == NULL) goto err; 762 } 763 break; 764 } 765 766 // read the interpreter and it's segments 767 case PT_INTERP: { 768 char interp_name[BUF_SIZE]; 769 770 pread(ph->core->exec_fd, interp_name, MIN(exec_php->p_filesz, BUF_SIZE), exec_php->p_offset); 771 print_debug("ELF interpreter %s\n", interp_name); 772 // read interpreter segments as well 773 if ((ph->core->interp_fd = pathmap_open(interp_name)) < 0) { 774 print_debug("can't open runtime loader\n"); 775 goto err; 776 } 777 break; 778 } 779 780 // from PT_DYNAMIC we want to read address of first link_map addr 781 case PT_DYNAMIC: { 782 ph->core->dynamic_addr = exec_php->p_vaddr; 783 print_debug("address of _DYNAMIC is 0x%lx\n", ph->core->dynamic_addr); 784 break; 785 } 786 787 } // switch 788 exec_php++; 789 } // for 790 791 free(phbuf); 792 return true; 793 err: 794 free(phbuf); 795 return false; 796 } 797 798 799 #define FIRST_LINK_MAP_OFFSET offsetof(struct r_debug, r_map) 800 #define LD_BASE_OFFSET offsetof(struct r_debug, r_ldbase) 801 #define LINK_MAP_ADDR_OFFSET offsetof(struct link_map, l_addr) 802 #define LINK_MAP_NAME_OFFSET offsetof(struct link_map, l_name) 803 #define LINK_MAP_NEXT_OFFSET offsetof(struct link_map, l_next) 804 805 // read shared library info from runtime linker's data structures. 806 // This work is done by librtlb_db in Solaris 807 static bool read_shared_lib_info(struct ps_prochandle* ph) { 808 uintptr_t addr = ph->core->dynamic_addr; 809 uintptr_t debug_base; 810 uintptr_t first_link_map_addr; 811 uintptr_t ld_base_addr; 812 uintptr_t link_map_addr; 813 uintptr_t lib_base_diff; 814 uintptr_t lib_base; 815 uintptr_t lib_name_addr; 816 char lib_name[BUF_SIZE]; 817 ELF_DYN dyn; 818 ELF_EHDR elf_ehdr; 819 int lib_fd; 820 821 // _DYNAMIC has information of the form 822 // [tag] [data] [tag] [data] ..... 823 // Both tag and data are pointer sized. 824 // We look for dynamic info with DT_DEBUG. This has shared object info. 825 // refer to struct r_debug in link.h 826 827 dyn.d_tag = DT_NULL; 828 while (dyn.d_tag != DT_DEBUG) { 829 if (ps_pdread(ph, (psaddr_t) addr, &dyn, sizeof(ELF_DYN)) != PS_OK) { 830 print_debug("can't read debug info from _DYNAMIC\n"); 831 return false; 832 } 833 addr += sizeof(ELF_DYN); 834 } 835 836 // we have got Dyn entry with DT_DEBUG 837 debug_base = dyn.d_un.d_ptr; 838 // at debug_base we have struct r_debug. This has first link map in r_map field 839 if (ps_pdread(ph, (psaddr_t) debug_base + FIRST_LINK_MAP_OFFSET, 840 &first_link_map_addr, sizeof(uintptr_t)) != PS_OK) { 841 print_debug("can't read first link map address\n"); 842 return false; 843 } 844 845 // read ld_base address from struct r_debug 846 if (ps_pdread(ph, (psaddr_t) debug_base + LD_BASE_OFFSET, &ld_base_addr, 847 sizeof(uintptr_t)) != PS_OK) { 848 print_debug("can't read ld base address\n"); 849 return false; 850 } 851 ph->core->ld_base_addr = ld_base_addr; 852 853 print_debug("interpreter base address is 0x%lx\n", ld_base_addr); 854 855 // now read segments from interp (i.e ld.so or ld-linux.so) 856 if (read_interp_segments(ph) != true) 857 return false; 858 859 // after adding interpreter (ld.so) mappings sort again 860 if (sort_map_array(ph) != true) 861 return false; 862 863 print_debug("first link map is at 0x%lx\n", first_link_map_addr); 864 865 link_map_addr = first_link_map_addr; 866 while (link_map_addr != 0) { 867 // read library base address of the .so. Note that even though <sys/link.h> calls 868 // link_map->l_addr as "base address", this is * not * really base virtual 869 // address of the shared object. This is actually the difference b/w the virtual 870 // address mentioned in shared object and the actual virtual base where runtime 871 // linker loaded it. We use "base diff" in read_lib_segments call below. 872 873 if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_ADDR_OFFSET, 874 &lib_base_diff, sizeof(uintptr_t)) != PS_OK) { 875 print_debug("can't read shared object base address diff\n"); 876 return false; 877 } 878 879 // read address of the name 880 if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_NAME_OFFSET, 881 &lib_name_addr, sizeof(uintptr_t)) != PS_OK) { 882 print_debug("can't read address of shared object name\n"); 883 return false; 884 } 885 886 // read name of the shared object 887 if (read_string(ph, (uintptr_t) lib_name_addr, lib_name, sizeof(lib_name)) != true) { 888 print_debug("can't read shared object name\n"); 889 return false; 890 } 891 892 if (lib_name[0] != '\0') { 893 // ignore empty lib names 894 lib_fd = pathmap_open(lib_name); 895 896 if (lib_fd < 0) { 897 print_debug("can't open shared object %s\n", lib_name); 898 // continue with other libraries... 899 } else { 900 if (read_elf_header(lib_fd, &elf_ehdr)) { 901 lib_base = lib_base_diff + find_base_address(lib_fd, &elf_ehdr); 902 print_debug("reading library %s @ 0x%lx [ 0x%lx ]\n", 903 lib_name, lib_base, lib_base_diff); 904 // while adding library mappings we need to use "base difference". 905 if (! read_lib_segments(ph, lib_fd, &elf_ehdr, lib_base_diff)) { 906 print_debug("can't read shared object's segments\n"); 907 close(lib_fd); 908 return false; 909 } 910 add_lib_info_fd(ph, lib_name, lib_fd, lib_base); 911 // Map info is added for the library (lib_name) so 912 // we need to re-sort it before calling the p_pdread. 913 if (sort_map_array(ph) != true) 914 return false; 915 } else { 916 print_debug("can't read ELF header for shared object %s\n", lib_name); 917 close(lib_fd); 918 // continue with other libraries... 919 } 920 } 921 } 922 923 // read next link_map address 924 if (ps_pdread(ph, (psaddr_t) link_map_addr + LINK_MAP_NEXT_OFFSET, 925 &link_map_addr, sizeof(uintptr_t)) != PS_OK) { 926 print_debug("can't read next link in link_map\n"); 927 return false; 928 } 929 } 930 931 return true; 932 } 933 934 // the one and only one exposed stuff from this file 935 struct ps_prochandle* Pgrab_core(const char* exec_file, const char* core_file) { 936 ELF_EHDR core_ehdr; 937 ELF_EHDR exec_ehdr; 938 ELF_EHDR lib_ehdr; 939 940 struct ps_prochandle* ph = (struct ps_prochandle*) calloc(1, sizeof(struct ps_prochandle)); 941 if (ph == NULL) { 942 print_debug("can't allocate ps_prochandle\n"); 943 return NULL; 944 } 945 946 if ((ph->core = (struct core_data*) calloc(1, sizeof(struct core_data))) == NULL) { 947 free(ph); 948 print_debug("can't allocate ps_prochandle\n"); 949 return NULL; 950 } 951 952 // initialize ph 953 ph->ops = &core_ops; 954 ph->core->core_fd = -1; 955 ph->core->exec_fd = -1; 956 ph->core->interp_fd = -1; 957 958 // open the core file 959 if ((ph->core->core_fd = open(core_file, O_RDONLY)) < 0) { 960 print_debug("can't open core file\n"); 961 goto err; 962 } 963 964 // read core file ELF header 965 if (read_elf_header(ph->core->core_fd, &core_ehdr) != true || core_ehdr.e_type != ET_CORE) { 966 print_debug("core file is not a valid ELF ET_CORE file\n"); 967 goto err; 968 } 969 970 if ((ph->core->exec_fd = open(exec_file, O_RDONLY)) < 0) { 971 print_debug("can't open executable file\n"); 972 goto err; 973 } 974 975 if (read_elf_header(ph->core->exec_fd, &exec_ehdr) != true || exec_ehdr.e_type != ET_EXEC) { 976 print_debug("executable file is not a valid ELF ET_EXEC file\n"); 977 goto err; 978 } 979 980 // process core file segments 981 if (read_core_segments(ph, &core_ehdr) != true) 982 goto err; 983 984 // process exec file segments 985 if (read_exec_segments(ph, &exec_ehdr) != true) 986 goto err; 987 988 // exec file is also treated like a shared object for symbol search 989 if (add_lib_info_fd(ph, exec_file, ph->core->exec_fd, 990 (uintptr_t)0 + find_base_address(ph->core->exec_fd, &exec_ehdr)) == NULL) 991 goto err; 992 993 // allocate and sort maps into map_array, we need to do this 994 // here because read_shared_lib_info needs to read from debuggee 995 // address space 996 if (sort_map_array(ph) != true) 997 goto err; 998 999 if (read_shared_lib_info(ph) != true) 1000 goto err; 1001 1002 // sort again because we have added more mappings from shared objects 1003 if (sort_map_array(ph) != true) 1004 goto err; 1005 1006 if (init_classsharing_workaround(ph) != true) 1007 goto err; 1008 1009 return ph; 1010 1011 err: 1012 Prelease(ph); 1013 return NULL; 1014 }