1 /* Generate a core file for the inferior process. 2 3 Copyright (C) 2001-2012 Free Software Foundation, Inc. 4 5 This file is part of GDB. 6 7 This program is free software; you can redistribute it and/or modify 8 it under the terms of the GNU General Public License as published by 9 the Free Software Foundation; either version 3 of the License, or 10 (at your option) any later version. 11 12 This program is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 GNU General Public License for more details. 16 17 You should have received a copy of the GNU General Public License 18 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 19 20 #include "defs.h" 21 #include "elf-bfd.h" 22 #include "infcall.h" 23 #include "inferior.h" 24 #include "gdbcore.h" 25 #include "objfiles.h" 26 #include "solib.h" 27 #include "symfile.h" 28 #include "arch-utils.h" 29 #include "completer.h" 30 #include "gcore.h" 31 #include "cli/cli-decode.h" 32 #include "gdb_assert.h" 33 #include <fcntl.h> 34 #include "regcache.h" 35 #include "regset.h" 36 37 /* The largest amount of memory to read from the target at once. We 38 must throttle it to limit the amount of memory used by GDB during 39 generate-core-file for programs with large resident data. */ 40 #define MAX_COPY_BYTES (1024 * 1024) 41 42 static const char *default_gcore_target (void); 43 static enum bfd_architecture default_gcore_arch (void); 44 static unsigned long default_gcore_mach (void); 45 static int gcore_memory_sections (bfd *); 46 47 /* create_gcore_bfd -- helper for gcore_command (exported). 48 Open a new bfd core file for output, and return the handle. */ 49 50 bfd * 51 create_gcore_bfd (char *filename) 52 { 53 bfd *obfd = bfd_openw (filename, default_gcore_target ()); 54 55 if (!obfd) 56 error (_("Failed to open '%s' for output."), filename); 57 bfd_set_format (obfd, bfd_core); 58 bfd_set_arch_mach (obfd, default_gcore_arch (), default_gcore_mach ()); 59 return obfd; 60 } 61 62 /* write_gcore_file -- helper for gcore_command (exported). 63 Compose and write the corefile data to the core file. */ 64 65 66 void 67 write_gcore_file (bfd *obfd) 68 { 69 void *note_data = NULL; 70 int note_size = 0; 71 asection *note_sec = NULL; 72 73 /* An external target method must build the notes section. */ 74 note_data = target_make_corefile_notes (obfd, ¬e_size); 75 76 /* Create the note section. */ 77 if (note_data != NULL && note_size != 0) 78 { 79 note_sec = bfd_make_section_anyway_with_flags (obfd, "note0", 80 SEC_HAS_CONTENTS 81 | SEC_READONLY 82 | SEC_ALLOC); 83 if (note_sec == NULL) 84 error (_("Failed to create 'note' section for corefile: %s"), 85 bfd_errmsg (bfd_get_error ())); 86 87 bfd_set_section_vma (obfd, note_sec, 0); 88 bfd_set_section_alignment (obfd, note_sec, 0); 89 bfd_set_section_size (obfd, note_sec, note_size); 90 } 91 92 /* Now create the memory/load sections. */ 93 if (gcore_memory_sections (obfd) == 0) 94 error (_("gcore: failed to get corefile memory sections from target.")); 95 96 /* Write out the contents of the note section. */ 97 if (note_data != NULL && note_size != 0) 98 { 99 if (!bfd_set_section_contents (obfd, note_sec, note_data, 0, note_size)) 100 warning (_("writing note section (%s)"), 101 bfd_errmsg (bfd_get_error ())); 102 } 103 } 104 105 static void 106 do_bfd_delete_cleanup (void *arg) 107 { 108 bfd *obfd = arg; 109 const char *filename = obfd->filename; 110 111 bfd_close (arg); 112 unlink (filename); 113 } 114 115 /* gcore_command -- implements the 'gcore' command. 116 Generate a core file from the inferior process. */ 117 118 static void 119 gcore_command (char *args, int from_tty) 120 { 121 struct cleanup *old_chain; 122 char *corefilename, corefilename_buffer[40]; 123 bfd *obfd; 124 125 /* No use generating a corefile without a target process. */ 126 if (!target_has_execution) 127 noprocess (); 128 129 if (args && *args) 130 corefilename = args; 131 else 132 { 133 /* Default corefile name is "core.PID". */ 134 sprintf (corefilename_buffer, "core.%d", PIDGET (inferior_ptid)); 135 corefilename = corefilename_buffer; 136 } 137 138 if (info_verbose) 139 fprintf_filtered (gdb_stdout, 140 "Opening corefile '%s' for output.\n", corefilename); 141 142 /* Open the output file. */ 143 obfd = create_gcore_bfd (corefilename); 144 145 /* Need a cleanup that will close and delete the file. */ 146 old_chain = make_cleanup (do_bfd_delete_cleanup, obfd); 147 148 /* Call worker function. */ 149 write_gcore_file (obfd); 150 151 /* Succeeded. */ 152 fprintf_filtered (gdb_stdout, "Saved corefile %s\n", corefilename); 153 154 discard_cleanups (old_chain); 155 bfd_close (obfd); 156 } 157 158 static unsigned long 159 default_gcore_mach (void) 160 { 161 #if 1 /* See if this even matters... */ 162 return 0; 163 #else 164 165 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch); 166 167 if (bfdarch != NULL) 168 return bfdarch->mach; 169 if (exec_bfd == NULL) 170 error (_("Can't find default bfd machine type (need execfile).")); 171 172 return bfd_get_mach (exec_bfd); 173 #endif /* 1 */ 174 } 175 176 static enum bfd_architecture 177 default_gcore_arch (void) 178 { 179 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch); 180 181 if (bfdarch != NULL) 182 return bfdarch->arch; 183 if (exec_bfd == NULL) 184 error (_("Can't find bfd architecture for corefile (need execfile).")); 185 186 return bfd_get_arch (exec_bfd); 187 } 188 189 static const char * 190 default_gcore_target (void) 191 { 192 /* The gdbarch may define a target to use for core files. */ 193 if (gdbarch_gcore_bfd_target_p (target_gdbarch)) 194 return gdbarch_gcore_bfd_target (target_gdbarch); 195 196 /* Otherwise, try to fall back to the exec_bfd target. This will probably 197 not work for non-ELF targets. */ 198 if (exec_bfd == NULL) 199 return NULL; 200 else 201 return bfd_get_target (exec_bfd); 202 } 203 204 /* Derive a reasonable stack segment by unwinding the target stack, 205 and store its limits in *BOTTOM and *TOP. Return non-zero if 206 successful. */ 207 208 static int 209 derive_stack_segment (bfd_vma *bottom, bfd_vma *top) 210 { 211 struct frame_info *fi, *tmp_fi; 212 213 gdb_assert (bottom); 214 gdb_assert (top); 215 216 /* Can't succeed without stack and registers. */ 217 if (!target_has_stack || !target_has_registers) 218 return 0; 219 220 /* Can't succeed without current frame. */ 221 fi = get_current_frame (); 222 if (fi == NULL) 223 return 0; 224 225 /* Save frame pointer of TOS frame. */ 226 *top = get_frame_base (fi); 227 /* If current stack pointer is more "inner", use that instead. */ 228 if (gdbarch_inner_than (get_frame_arch (fi), get_frame_sp (fi), *top)) 229 *top = get_frame_sp (fi); 230 231 /* Find prev-most frame. */ 232 while ((tmp_fi = get_prev_frame (fi)) != NULL) 233 fi = tmp_fi; 234 235 /* Save frame pointer of prev-most frame. */ 236 *bottom = get_frame_base (fi); 237 238 /* Now canonicalize their order, so that BOTTOM is a lower address 239 (as opposed to a lower stack frame). */ 240 if (*bottom > *top) 241 { 242 bfd_vma tmp_vma; 243 244 tmp_vma = *top; 245 *top = *bottom; 246 *bottom = tmp_vma; 247 } 248 249 return 1; 250 } 251 252 /* call_target_sbrk -- 253 helper function for derive_heap_segment. */ 254 255 static bfd_vma 256 call_target_sbrk (int sbrk_arg) 257 { 258 struct objfile *sbrk_objf; 259 struct gdbarch *gdbarch; 260 bfd_vma top_of_heap; 261 struct value *target_sbrk_arg; 262 struct value *sbrk_fn, *ret; 263 bfd_vma tmp; 264 265 if (lookup_minimal_symbol ("sbrk", NULL, NULL) != NULL) 266 { 267 sbrk_fn = find_function_in_inferior ("sbrk", &sbrk_objf); 268 if (sbrk_fn == NULL) 269 return (bfd_vma) 0; 270 } 271 else if (lookup_minimal_symbol ("_sbrk", NULL, NULL) != NULL) 272 { 273 sbrk_fn = find_function_in_inferior ("_sbrk", &sbrk_objf); 274 if (sbrk_fn == NULL) 275 return (bfd_vma) 0; 276 } 277 else 278 return (bfd_vma) 0; 279 280 gdbarch = get_objfile_arch (sbrk_objf); 281 target_sbrk_arg = value_from_longest (builtin_type (gdbarch)->builtin_int, 282 sbrk_arg); 283 gdb_assert (target_sbrk_arg); 284 ret = call_function_by_hand (sbrk_fn, 1, &target_sbrk_arg); 285 if (ret == NULL) 286 return (bfd_vma) 0; 287 288 tmp = value_as_long (ret); 289 if ((LONGEST) tmp <= 0 || (LONGEST) tmp == 0xffffffff) 290 return (bfd_vma) 0; 291 292 top_of_heap = tmp; 293 return top_of_heap; 294 } 295 296 /* Derive a reasonable heap segment for ABFD by looking at sbrk and 297 the static data sections. Store its limits in *BOTTOM and *TOP. 298 Return non-zero if successful. */ 299 300 static int 301 derive_heap_segment (bfd *abfd, bfd_vma *bottom, bfd_vma *top) 302 { 303 bfd_vma top_of_data_memory = 0; 304 bfd_vma top_of_heap = 0; 305 bfd_size_type sec_size; 306 bfd_vma sec_vaddr; 307 asection *sec; 308 309 gdb_assert (bottom); 310 gdb_assert (top); 311 312 /* This function depends on being able to call a function in the 313 inferior. */ 314 if (!target_has_execution) 315 return 0; 316 317 /* The following code assumes that the link map is arranged as 318 follows (low to high addresses): 319 320 --------------------------------- 321 | text sections | 322 --------------------------------- 323 | data sections (including bss) | 324 --------------------------------- 325 | heap | 326 --------------------------------- */ 327 328 for (sec = abfd->sections; sec; sec = sec->next) 329 { 330 if (bfd_get_section_flags (abfd, sec) & SEC_DATA 331 || strcmp (".bss", bfd_section_name (abfd, sec)) == 0) 332 { 333 sec_vaddr = bfd_get_section_vma (abfd, sec); 334 sec_size = bfd_get_section_size (sec); 335 if (sec_vaddr + sec_size > top_of_data_memory) 336 top_of_data_memory = sec_vaddr + sec_size; 337 } 338 } 339 340 top_of_heap = call_target_sbrk (0); 341 if (top_of_heap == (bfd_vma) 0) 342 return 0; 343 344 /* Return results. */ 345 if (top_of_heap > top_of_data_memory) 346 { 347 *bottom = top_of_data_memory; 348 *top = top_of_heap; 349 return 1; 350 } 351 352 /* No additional heap space needs to be saved. */ 353 return 0; 354 } 355 356 static void 357 make_output_phdrs (bfd *obfd, asection *osec, void *ignored) 358 { 359 int p_flags = 0; 360 int p_type = 0; 361 362 /* FIXME: these constants may only be applicable for ELF. */ 363 if (strncmp (bfd_section_name (obfd, osec), "load", 4) == 0) 364 p_type = PT_LOAD; 365 else if (strncmp (bfd_section_name (obfd, osec), "note", 4) == 0) 366 p_type = PT_NOTE; 367 else 368 p_type = PT_NULL; 369 370 p_flags |= PF_R; /* Segment is readable. */ 371 if (!(bfd_get_section_flags (obfd, osec) & SEC_READONLY)) 372 p_flags |= PF_W; /* Segment is writable. */ 373 if (bfd_get_section_flags (obfd, osec) & SEC_CODE) 374 p_flags |= PF_X; /* Segment is executable. */ 375 376 bfd_record_phdr (obfd, p_type, 1, p_flags, 0, 0, 0, 0, 1, &osec); 377 } 378 379 static int 380 gcore_create_callback (CORE_ADDR vaddr, unsigned long size, 381 int read, int write, int exec, void *data) 382 { 383 bfd *obfd = data; 384 asection *osec; 385 flagword flags = SEC_ALLOC | SEC_HAS_CONTENTS | SEC_LOAD; 386 387 /* If the memory segment has no permissions set, ignore it, otherwise 388 when we later try to access it for read/write, we'll get an error 389 or jam the kernel. */ 390 if (read == 0 && write == 0 && exec == 0) 391 { 392 if (info_verbose) 393 { 394 fprintf_filtered (gdb_stdout, "Ignore segment, %s bytes at %s\n", 395 plongest (size), paddress (target_gdbarch, vaddr)); 396 } 397 398 return 0; 399 } 400 401 if (write == 0 && !solib_keep_data_in_core (vaddr, size)) 402 { 403 /* See if this region of memory lies inside a known file on disk. 404 If so, we can avoid copying its contents by clearing SEC_LOAD. */ 405 struct objfile *objfile; 406 struct obj_section *objsec; 407 408 ALL_OBJSECTIONS (objfile, objsec) 409 { 410 bfd *abfd = objfile->obfd; 411 asection *asec = objsec->the_bfd_section; 412 bfd_vma align = (bfd_vma) 1 << bfd_get_section_alignment (abfd, 413 asec); 414 bfd_vma start = obj_section_addr (objsec) & -align; 415 bfd_vma end = (obj_section_endaddr (objsec) + align - 1) & -align; 416 417 /* Match if either the entire memory region lies inside the 418 section (i.e. a mapping covering some pages of a large 419 segment) or the entire section lies inside the memory region 420 (i.e. a mapping covering multiple small sections). 421 422 This BFD was synthesized from reading target memory, 423 we don't want to omit that. */ 424 if (((vaddr >= start && vaddr + size <= end) 425 || (start >= vaddr && end <= vaddr + size)) 426 && !(bfd_get_file_flags (abfd) & BFD_IN_MEMORY)) 427 { 428 flags &= ~(SEC_LOAD | SEC_HAS_CONTENTS); 429 goto keep; /* Break out of two nested for loops. */ 430 } 431 } 432 433 keep: 434 flags |= SEC_READONLY; 435 } 436 437 if (exec) 438 flags |= SEC_CODE; 439 else 440 flags |= SEC_DATA; 441 442 osec = bfd_make_section_anyway_with_flags (obfd, "load", flags); 443 if (osec == NULL) 444 { 445 warning (_("Couldn't make gcore segment: %s"), 446 bfd_errmsg (bfd_get_error ())); 447 return 1; 448 } 449 450 if (info_verbose) 451 { 452 fprintf_filtered (gdb_stdout, "Save segment, %s bytes at %s\n", 453 plongest (size), paddress (target_gdbarch, vaddr)); 454 } 455 456 bfd_set_section_size (obfd, osec, size); 457 bfd_set_section_vma (obfd, osec, vaddr); 458 bfd_section_lma (obfd, osec) = 0; /* ??? bfd_set_section_lma? */ 459 return 0; 460 } 461 462 static int 463 objfile_find_memory_regions (find_memory_region_ftype func, void *obfd) 464 { 465 /* Use objfile data to create memory sections. */ 466 struct objfile *objfile; 467 struct obj_section *objsec; 468 bfd_vma temp_bottom, temp_top; 469 470 /* Call callback function for each objfile section. */ 471 ALL_OBJSECTIONS (objfile, objsec) 472 { 473 bfd *ibfd = objfile->obfd; 474 asection *isec = objsec->the_bfd_section; 475 flagword flags = bfd_get_section_flags (ibfd, isec); 476 477 if ((flags & SEC_ALLOC) || (flags & SEC_LOAD)) 478 { 479 int size = bfd_section_size (ibfd, isec); 480 int ret; 481 482 ret = (*func) (obj_section_addr (objsec), size, 483 1, /* All sections will be readable. */ 484 (flags & SEC_READONLY) == 0, /* Writable. */ 485 (flags & SEC_CODE) != 0, /* Executable. */ 486 obfd); 487 if (ret != 0) 488 return ret; 489 } 490 } 491 492 /* Make a stack segment. */ 493 if (derive_stack_segment (&temp_bottom, &temp_top)) 494 (*func) (temp_bottom, temp_top - temp_bottom, 495 1, /* Stack section will be readable. */ 496 1, /* Stack section will be writable. */ 497 0, /* Stack section will not be executable. */ 498 obfd); 499 500 /* Make a heap segment. */ 501 if (derive_heap_segment (exec_bfd, &temp_bottom, &temp_top)) 502 (*func) (temp_bottom, temp_top - temp_bottom, 503 1, /* Heap section will be readable. */ 504 1, /* Heap section will be writable. */ 505 0, /* Heap section will not be executable. */ 506 obfd); 507 508 return 0; 509 } 510 511 static void 512 gcore_copy_callback (bfd *obfd, asection *osec, void *ignored) 513 { 514 bfd_size_type size, total_size = bfd_section_size (obfd, osec); 515 file_ptr offset = 0; 516 struct cleanup *old_chain = NULL; 517 void *memhunk; 518 519 /* Read-only sections are marked; we don't have to copy their contents. */ 520 if ((bfd_get_section_flags (obfd, osec) & SEC_LOAD) == 0) 521 return; 522 523 /* Only interested in "load" sections. */ 524 if (strncmp ("load", bfd_section_name (obfd, osec), 4) != 0) 525 return; 526 527 size = min (total_size, MAX_COPY_BYTES); 528 memhunk = xmalloc (size); 529 old_chain = make_cleanup (xfree, memhunk); 530 531 while (total_size > 0) 532 { 533 if (size > total_size) 534 size = total_size; 535 536 if (target_read_memory (bfd_section_vma (obfd, osec) + offset, 537 memhunk, size) != 0) 538 { 539 warning (_("Memory read failed for corefile " 540 "section, %s bytes at %s."), 541 plongest (size), 542 paddress (target_gdbarch, bfd_section_vma (obfd, osec))); 543 break; 544 } 545 if (!bfd_set_section_contents (obfd, osec, memhunk, offset, size)) 546 { 547 warning (_("Failed to write corefile contents (%s)."), 548 bfd_errmsg (bfd_get_error ())); 549 break; 550 } 551 552 total_size -= size; 553 offset += size; 554 } 555 556 do_cleanups (old_chain); /* Frees MEMHUNK. */ 557 } 558 559 static int 560 gcore_memory_sections (bfd *obfd) 561 { 562 if (target_find_memory_regions (gcore_create_callback, obfd) != 0) 563 return 0; /* FIXME: error return/msg? */ 564 565 /* Record phdrs for section-to-segment mapping. */ 566 bfd_map_over_sections (obfd, make_output_phdrs, NULL); 567 568 /* Copy memory region contents. */ 569 bfd_map_over_sections (obfd, gcore_copy_callback, NULL); 570 571 return 1; 572 } 573 574 /* Provide a prototype to silence -Wmissing-prototypes. */ 575 extern initialize_file_ftype _initialize_gcore; 576 577 void 578 _initialize_gcore (void) 579 { 580 add_com ("generate-core-file", class_files, gcore_command, _("\ 581 Save a core file with the current state of the debugged process.\n\ 582 Argument is optional filename. Default filename is 'core.<process_id>'.")); 583 584 add_com_alias ("gcore", "generate-core-file", class_files, 1); 585 exec_set_find_memory_regions (objfile_find_memory_regions); 586 } 587