gcore.c revision 1.6
1/* Generate a core file for the inferior process. 2 3 Copyright (C) 2001-2016 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 <fcntl.h> 33#include "regcache.h" 34#include "regset.h" 35#include "gdb_bfd.h" 36#include "readline/tilde.h" 37 38/* The largest amount of memory to read from the target at once. We 39 must throttle it to limit the amount of memory used by GDB during 40 generate-core-file for programs with large resident data. */ 41#define MAX_COPY_BYTES (1024 * 1024) 42 43static const char *default_gcore_target (void); 44static enum bfd_architecture default_gcore_arch (void); 45static unsigned long default_gcore_mach (void); 46static int gcore_memory_sections (bfd *); 47 48/* create_gcore_bfd -- helper for gcore_command (exported). 49 Open a new bfd core file for output, and return the handle. */ 50 51bfd * 52create_gcore_bfd (const char *filename) 53{ 54 bfd *obfd = gdb_bfd_openw (filename, default_gcore_target ()); 55 56 if (!obfd) 57 error (_("Failed to open '%s' for output."), filename); 58 bfd_set_format (obfd, bfd_core); 59 bfd_set_arch_mach (obfd, default_gcore_arch (), default_gcore_mach ()); 60 return obfd; 61} 62 63/* write_gcore_file_1 -- do the actual work of write_gcore_file. */ 64 65static void 66write_gcore_file_1 (bfd *obfd) 67{ 68 struct cleanup *cleanup; 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 /* FIXME: uweigand/2011-10-06: All architectures that support core file 75 generation should be converted to gdbarch_make_corefile_notes; at that 76 point, the target vector method can be removed. */ 77 if (!gdbarch_make_corefile_notes_p (target_gdbarch ())) 78 note_data = target_make_corefile_notes (obfd, ¬e_size); 79 else 80 note_data = gdbarch_make_corefile_notes (target_gdbarch (), obfd, ¬e_size); 81 82 cleanup = make_cleanup (xfree, note_data); 83 84 if (note_data == NULL || note_size == 0) 85 error (_("Target does not support core file generation.")); 86 87 /* Create the note section. */ 88 note_sec = bfd_make_section_anyway_with_flags (obfd, "note0", 89 SEC_HAS_CONTENTS 90 | SEC_READONLY 91 | SEC_ALLOC); 92 if (note_sec == NULL) 93 error (_("Failed to create 'note' section for corefile: %s"), 94 bfd_errmsg (bfd_get_error ())); 95 96 bfd_set_section_vma (obfd, note_sec, 0); 97 bfd_set_section_alignment (obfd, note_sec, 0); 98 bfd_set_section_size (obfd, note_sec, note_size); 99 100 /* Now create the memory/load sections. */ 101 if (gcore_memory_sections (obfd) == 0) 102 error (_("gcore: failed to get corefile memory sections from target.")); 103 104 /* Write out the contents of the note section. */ 105 if (!bfd_set_section_contents (obfd, note_sec, note_data, 0, note_size)) 106 warning (_("writing note section (%s)"), bfd_errmsg (bfd_get_error ())); 107 108 do_cleanups (cleanup); 109} 110 111/* write_gcore_file -- helper for gcore_command (exported). 112 Compose and write the corefile data to the core file. */ 113 114void 115write_gcore_file (bfd *obfd) 116{ 117 struct gdb_exception except = exception_none; 118 119 target_prepare_to_generate_core (); 120 121 TRY 122 { 123 write_gcore_file_1 (obfd); 124 } 125 CATCH (e, RETURN_MASK_ALL) 126 { 127 except = e; 128 } 129 END_CATCH 130 131 target_done_generating_core (); 132 133 if (except.reason < 0) 134 throw_exception (except); 135} 136 137static void 138do_bfd_delete_cleanup (void *arg) 139{ 140 bfd *obfd = (bfd *) arg; 141 const char *filename = obfd->filename; 142 143 gdb_bfd_unref ((bfd *) arg); 144 unlink (filename); 145} 146 147/* gcore_command -- implements the 'gcore' command. 148 Generate a core file from the inferior process. */ 149 150static void 151gcore_command (char *args, int from_tty) 152{ 153 struct cleanup *filename_chain; 154 struct cleanup *bfd_chain; 155 char *corefilename; 156 bfd *obfd; 157 158 /* No use generating a corefile without a target process. */ 159 if (!target_has_execution) 160 noprocess (); 161 162 if (args && *args) 163 corefilename = tilde_expand (args); 164 else 165 { 166 /* Default corefile name is "core.PID". */ 167 corefilename = xstrprintf ("core.%d", ptid_get_pid (inferior_ptid)); 168 } 169 filename_chain = make_cleanup (xfree, corefilename); 170 171 if (info_verbose) 172 fprintf_filtered (gdb_stdout, 173 "Opening corefile '%s' for output.\n", corefilename); 174 175 /* Open the output file. */ 176 obfd = create_gcore_bfd (corefilename); 177 178 /* Need a cleanup that will close and delete the file. */ 179 bfd_chain = make_cleanup (do_bfd_delete_cleanup, obfd); 180 181 /* Call worker function. */ 182 write_gcore_file (obfd); 183 184 /* Succeeded. */ 185 discard_cleanups (bfd_chain); 186 gdb_bfd_unref (obfd); 187 188 fprintf_filtered (gdb_stdout, "Saved corefile %s\n", corefilename); 189 do_cleanups (filename_chain); 190} 191 192static unsigned long 193default_gcore_mach (void) 194{ 195#if 1 /* See if this even matters... */ 196 return 0; 197#else 198 199 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch ()); 200 201 if (bfdarch != NULL) 202 return bfdarch->mach; 203 if (exec_bfd == NULL) 204 error (_("Can't find default bfd machine type (need execfile).")); 205 206 return bfd_get_mach (exec_bfd); 207#endif /* 1 */ 208} 209 210static enum bfd_architecture 211default_gcore_arch (void) 212{ 213 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch ()); 214 215 if (bfdarch != NULL) 216 return bfdarch->arch; 217 if (exec_bfd == NULL) 218 error (_("Can't find bfd architecture for corefile (need execfile).")); 219 220 return bfd_get_arch (exec_bfd); 221} 222 223static const char * 224default_gcore_target (void) 225{ 226 /* The gdbarch may define a target to use for core files. */ 227 if (gdbarch_gcore_bfd_target_p (target_gdbarch ())) 228 return gdbarch_gcore_bfd_target (target_gdbarch ()); 229 230 /* Otherwise, try to fall back to the exec_bfd target. This will probably 231 not work for non-ELF targets. */ 232 if (exec_bfd == NULL) 233 return NULL; 234 else 235 return bfd_get_target (exec_bfd); 236} 237 238/* Derive a reasonable stack segment by unwinding the target stack, 239 and store its limits in *BOTTOM and *TOP. Return non-zero if 240 successful. */ 241 242static int 243derive_stack_segment (bfd_vma *bottom, bfd_vma *top) 244{ 245 struct frame_info *fi, *tmp_fi; 246 247 gdb_assert (bottom); 248 gdb_assert (top); 249 250 /* Can't succeed without stack and registers. */ 251 if (!target_has_stack || !target_has_registers) 252 return 0; 253 254 /* Can't succeed without current frame. */ 255 fi = get_current_frame (); 256 if (fi == NULL) 257 return 0; 258 259 /* Save frame pointer of TOS frame. */ 260 *top = get_frame_base (fi); 261 /* If current stack pointer is more "inner", use that instead. */ 262 if (gdbarch_inner_than (get_frame_arch (fi), get_frame_sp (fi), *top)) 263 *top = get_frame_sp (fi); 264 265 /* Find prev-most frame. */ 266 while ((tmp_fi = get_prev_frame (fi)) != NULL) 267 fi = tmp_fi; 268 269 /* Save frame pointer of prev-most frame. */ 270 *bottom = get_frame_base (fi); 271 272 /* Now canonicalize their order, so that BOTTOM is a lower address 273 (as opposed to a lower stack frame). */ 274 if (*bottom > *top) 275 { 276 bfd_vma tmp_vma; 277 278 tmp_vma = *top; 279 *top = *bottom; 280 *bottom = tmp_vma; 281 } 282 283 return 1; 284} 285 286/* call_target_sbrk -- 287 helper function for derive_heap_segment. */ 288 289static bfd_vma 290call_target_sbrk (int sbrk_arg) 291{ 292 struct objfile *sbrk_objf; 293 struct gdbarch *gdbarch; 294 bfd_vma top_of_heap; 295 struct value *target_sbrk_arg; 296 struct value *sbrk_fn, *ret; 297 bfd_vma tmp; 298 299 if (lookup_minimal_symbol ("sbrk", NULL, NULL).minsym != NULL) 300 { 301 sbrk_fn = find_function_in_inferior ("sbrk", &sbrk_objf); 302 if (sbrk_fn == NULL) 303 return (bfd_vma) 0; 304 } 305 else if (lookup_minimal_symbol ("_sbrk", NULL, NULL).minsym != NULL) 306 { 307 sbrk_fn = find_function_in_inferior ("_sbrk", &sbrk_objf); 308 if (sbrk_fn == NULL) 309 return (bfd_vma) 0; 310 } 311 else 312 return (bfd_vma) 0; 313 314 gdbarch = get_objfile_arch (sbrk_objf); 315 target_sbrk_arg = value_from_longest (builtin_type (gdbarch)->builtin_int, 316 sbrk_arg); 317 gdb_assert (target_sbrk_arg); 318 ret = call_function_by_hand (sbrk_fn, 1, &target_sbrk_arg); 319 if (ret == NULL) 320 return (bfd_vma) 0; 321 322 tmp = value_as_long (ret); 323 if ((LONGEST) tmp <= 0 || (LONGEST) tmp == 0xffffffff) 324 return (bfd_vma) 0; 325 326 top_of_heap = tmp; 327 return top_of_heap; 328} 329 330/* Derive a reasonable heap segment for ABFD by looking at sbrk and 331 the static data sections. Store its limits in *BOTTOM and *TOP. 332 Return non-zero if successful. */ 333 334static int 335derive_heap_segment (bfd *abfd, bfd_vma *bottom, bfd_vma *top) 336{ 337 bfd_vma top_of_data_memory = 0; 338 bfd_vma top_of_heap = 0; 339 bfd_size_type sec_size; 340 bfd_vma sec_vaddr; 341 asection *sec; 342 343 gdb_assert (bottom); 344 gdb_assert (top); 345 346 /* This function depends on being able to call a function in the 347 inferior. */ 348 if (!target_has_execution) 349 return 0; 350 351 /* The following code assumes that the link map is arranged as 352 follows (low to high addresses): 353 354 --------------------------------- 355 | text sections | 356 --------------------------------- 357 | data sections (including bss) | 358 --------------------------------- 359 | heap | 360 --------------------------------- */ 361 362 for (sec = abfd->sections; sec; sec = sec->next) 363 { 364 if (bfd_get_section_flags (abfd, sec) & SEC_DATA 365 || strcmp (".bss", bfd_section_name (abfd, sec)) == 0) 366 { 367 sec_vaddr = bfd_get_section_vma (abfd, sec); 368 sec_size = bfd_get_section_size (sec); 369 if (sec_vaddr + sec_size > top_of_data_memory) 370 top_of_data_memory = sec_vaddr + sec_size; 371 } 372 } 373 374 top_of_heap = call_target_sbrk (0); 375 if (top_of_heap == (bfd_vma) 0) 376 return 0; 377 378 /* Return results. */ 379 if (top_of_heap > top_of_data_memory) 380 { 381 *bottom = top_of_data_memory; 382 *top = top_of_heap; 383 return 1; 384 } 385 386 /* No additional heap space needs to be saved. */ 387 return 0; 388} 389 390static void 391make_output_phdrs (bfd *obfd, asection *osec, void *ignored) 392{ 393 int p_flags = 0; 394 int p_type = 0; 395 396 /* FIXME: these constants may only be applicable for ELF. */ 397 if (startswith (bfd_section_name (obfd, osec), "load")) 398 p_type = PT_LOAD; 399 else if (startswith (bfd_section_name (obfd, osec), "note")) 400 p_type = PT_NOTE; 401 else 402 p_type = PT_NULL; 403 404 p_flags |= PF_R; /* Segment is readable. */ 405 if (!(bfd_get_section_flags (obfd, osec) & SEC_READONLY)) 406 p_flags |= PF_W; /* Segment is writable. */ 407 if (bfd_get_section_flags (obfd, osec) & SEC_CODE) 408 p_flags |= PF_X; /* Segment is executable. */ 409 410 bfd_record_phdr (obfd, p_type, 1, p_flags, 0, 0, 0, 0, 1, &osec); 411} 412 413/* find_memory_region_ftype implementation. DATA is 'bfd *' for the core file 414 GDB is creating. */ 415 416static int 417gcore_create_callback (CORE_ADDR vaddr, unsigned long size, int read, 418 int write, int exec, int modified, void *data) 419{ 420 bfd *obfd = (bfd *) data; 421 asection *osec; 422 flagword flags = SEC_ALLOC | SEC_HAS_CONTENTS | SEC_LOAD; 423 424 /* If the memory segment has no permissions set, ignore it, otherwise 425 when we later try to access it for read/write, we'll get an error 426 or jam the kernel. */ 427 if (read == 0 && write == 0 && exec == 0 && modified == 0) 428 { 429 if (info_verbose) 430 { 431 fprintf_filtered (gdb_stdout, "Ignore segment, %s bytes at %s\n", 432 plongest (size), paddress (target_gdbarch (), vaddr)); 433 } 434 435 return 0; 436 } 437 438 if (write == 0 && modified == 0 && !solib_keep_data_in_core (vaddr, size)) 439 { 440 /* See if this region of memory lies inside a known file on disk. 441 If so, we can avoid copying its contents by clearing SEC_LOAD. */ 442 struct objfile *objfile; 443 struct obj_section *objsec; 444 445 ALL_OBJSECTIONS (objfile, objsec) 446 { 447 bfd *abfd = objfile->obfd; 448 asection *asec = objsec->the_bfd_section; 449 bfd_vma align = (bfd_vma) 1 << bfd_get_section_alignment (abfd, 450 asec); 451 bfd_vma start = obj_section_addr (objsec) & -align; 452 bfd_vma end = (obj_section_endaddr (objsec) + align - 1) & -align; 453 454 /* Match if either the entire memory region lies inside the 455 section (i.e. a mapping covering some pages of a large 456 segment) or the entire section lies inside the memory region 457 (i.e. a mapping covering multiple small sections). 458 459 This BFD was synthesized from reading target memory, 460 we don't want to omit that. */ 461 if (objfile->separate_debug_objfile_backlink == NULL 462 && ((vaddr >= start && vaddr + size <= end) 463 || (start >= vaddr && end <= vaddr + size)) 464 && !(bfd_get_file_flags (abfd) & BFD_IN_MEMORY)) 465 { 466 flags &= ~(SEC_LOAD | SEC_HAS_CONTENTS); 467 goto keep; /* Break out of two nested for loops. */ 468 } 469 } 470 471 keep:; 472 } 473 474 if (write == 0) 475 flags |= SEC_READONLY; 476 477 if (exec) 478 flags |= SEC_CODE; 479 else 480 flags |= SEC_DATA; 481 482 osec = bfd_make_section_anyway_with_flags (obfd, "load", flags); 483 if (osec == NULL) 484 { 485 warning (_("Couldn't make gcore segment: %s"), 486 bfd_errmsg (bfd_get_error ())); 487 return 1; 488 } 489 490 if (info_verbose) 491 { 492 fprintf_filtered (gdb_stdout, "Save segment, %s bytes at %s\n", 493 plongest (size), paddress (target_gdbarch (), vaddr)); 494 } 495 496 bfd_set_section_size (obfd, osec, size); 497 bfd_set_section_vma (obfd, osec, vaddr); 498 bfd_section_lma (obfd, osec) = 0; /* ??? bfd_set_section_lma? */ 499 return 0; 500} 501 502int 503objfile_find_memory_regions (struct target_ops *self, 504 find_memory_region_ftype func, void *obfd) 505{ 506 /* Use objfile data to create memory sections. */ 507 struct objfile *objfile; 508 struct obj_section *objsec; 509 bfd_vma temp_bottom, temp_top; 510 511 /* Call callback function for each objfile section. */ 512 ALL_OBJSECTIONS (objfile, objsec) 513 { 514 bfd *ibfd = objfile->obfd; 515 asection *isec = objsec->the_bfd_section; 516 flagword flags = bfd_get_section_flags (ibfd, isec); 517 518 /* Separate debug info files are irrelevant for gcore. */ 519 if (objfile->separate_debug_objfile_backlink != NULL) 520 continue; 521 522 if ((flags & SEC_ALLOC) || (flags & SEC_LOAD)) 523 { 524 int size = bfd_section_size (ibfd, isec); 525 int ret; 526 527 ret = (*func) (obj_section_addr (objsec), size, 528 1, /* All sections will be readable. */ 529 (flags & SEC_READONLY) == 0, /* Writable. */ 530 (flags & SEC_CODE) != 0, /* Executable. */ 531 1, /* MODIFIED is unknown, pass it as true. */ 532 obfd); 533 if (ret != 0) 534 return ret; 535 } 536 } 537 538 /* Make a stack segment. */ 539 if (derive_stack_segment (&temp_bottom, &temp_top)) 540 (*func) (temp_bottom, temp_top - temp_bottom, 541 1, /* Stack section will be readable. */ 542 1, /* Stack section will be writable. */ 543 0, /* Stack section will not be executable. */ 544 1, /* Stack section will be modified. */ 545 obfd); 546 547 /* Make a heap segment. */ 548 if (derive_heap_segment (exec_bfd, &temp_bottom, &temp_top)) 549 (*func) (temp_bottom, temp_top - temp_bottom, 550 1, /* Heap section will be readable. */ 551 1, /* Heap section will be writable. */ 552 0, /* Heap section will not be executable. */ 553 1, /* Heap section will be modified. */ 554 obfd); 555 556 return 0; 557} 558 559static void 560gcore_copy_callback (bfd *obfd, asection *osec, void *ignored) 561{ 562 bfd_size_type size, total_size = bfd_section_size (obfd, osec); 563 file_ptr offset = 0; 564 struct cleanup *old_chain = NULL; 565 gdb_byte *memhunk; 566 567 /* Read-only sections are marked; we don't have to copy their contents. */ 568 if ((bfd_get_section_flags (obfd, osec) & SEC_LOAD) == 0) 569 return; 570 571 /* Only interested in "load" sections. */ 572 if (!startswith (bfd_section_name (obfd, osec), "load")) 573 return; 574 575 size = min (total_size, MAX_COPY_BYTES); 576 memhunk = (gdb_byte *) xmalloc (size); 577 old_chain = make_cleanup (xfree, memhunk); 578 579 while (total_size > 0) 580 { 581 if (size > total_size) 582 size = total_size; 583 584 if (target_read_memory (bfd_section_vma (obfd, osec) + offset, 585 memhunk, size) != 0) 586 { 587 warning (_("Memory read failed for corefile " 588 "section, %s bytes at %s."), 589 plongest (size), 590 paddress (target_gdbarch (), bfd_section_vma (obfd, osec))); 591 break; 592 } 593 if (!bfd_set_section_contents (obfd, osec, memhunk, offset, size)) 594 { 595 warning (_("Failed to write corefile contents (%s)."), 596 bfd_errmsg (bfd_get_error ())); 597 break; 598 } 599 600 total_size -= size; 601 offset += size; 602 } 603 604 do_cleanups (old_chain); /* Frees MEMHUNK. */ 605} 606 607static int 608gcore_memory_sections (bfd *obfd) 609{ 610 /* Try gdbarch method first, then fall back to target method. */ 611 if (!gdbarch_find_memory_regions_p (target_gdbarch ()) 612 || gdbarch_find_memory_regions (target_gdbarch (), 613 gcore_create_callback, obfd) != 0) 614 { 615 if (target_find_memory_regions (gcore_create_callback, obfd) != 0) 616 return 0; /* FIXME: error return/msg? */ 617 } 618 619 /* Record phdrs for section-to-segment mapping. */ 620 bfd_map_over_sections (obfd, make_output_phdrs, NULL); 621 622 /* Copy memory region contents. */ 623 bfd_map_over_sections (obfd, gcore_copy_callback, NULL); 624 625 return 1; 626} 627 628/* Provide a prototype to silence -Wmissing-prototypes. */ 629extern initialize_file_ftype _initialize_gcore; 630 631void 632_initialize_gcore (void) 633{ 634 add_com ("generate-core-file", class_files, gcore_command, _("\ 635Save a core file with the current state of the debugged process.\n\ 636Argument is optional filename. Default filename is 'core.<process_id>'.")); 637 638 add_com_alias ("gcore", "generate-core-file", class_files, 1); 639} 640