gcore.c revision 1.3
1/* Generate a core file for the inferior process. 2 3 Copyright (C) 2001-2015 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 volatile struct gdb_exception except; 118 119 target_prepare_to_generate_core (); 120 121 TRY_CATCH (except, RETURN_MASK_ALL) 122 write_gcore_file_1 (obfd); 123 124 target_done_generating_core (); 125 126 if (except.reason < 0) 127 throw_exception (except); 128} 129 130static void 131do_bfd_delete_cleanup (void *arg) 132{ 133 bfd *obfd = arg; 134 const char *filename = obfd->filename; 135 136 gdb_bfd_unref (arg); 137 unlink (filename); 138} 139 140/* gcore_command -- implements the 'gcore' command. 141 Generate a core file from the inferior process. */ 142 143static void 144gcore_command (char *args, int from_tty) 145{ 146 struct cleanup *filename_chain; 147 struct cleanup *bfd_chain; 148 char *corefilename; 149 bfd *obfd; 150 151 /* No use generating a corefile without a target process. */ 152 if (!target_has_execution) 153 noprocess (); 154 155 if (args && *args) 156 corefilename = tilde_expand (args); 157 else 158 { 159 /* Default corefile name is "core.PID". */ 160 corefilename = xstrprintf ("core.%d", ptid_get_pid (inferior_ptid)); 161 } 162 filename_chain = make_cleanup (xfree, corefilename); 163 164 if (info_verbose) 165 fprintf_filtered (gdb_stdout, 166 "Opening corefile '%s' for output.\n", corefilename); 167 168 /* Open the output file. */ 169 obfd = create_gcore_bfd (corefilename); 170 171 /* Need a cleanup that will close and delete the file. */ 172 bfd_chain = make_cleanup (do_bfd_delete_cleanup, obfd); 173 174 /* Call worker function. */ 175 write_gcore_file (obfd); 176 177 /* Succeeded. */ 178 discard_cleanups (bfd_chain); 179 gdb_bfd_unref (obfd); 180 181 fprintf_filtered (gdb_stdout, "Saved corefile %s\n", corefilename); 182 do_cleanups (filename_chain); 183} 184 185static unsigned long 186default_gcore_mach (void) 187{ 188#if 1 /* See if this even matters... */ 189 return 0; 190#else 191 192 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch ()); 193 194 if (bfdarch != NULL) 195 return bfdarch->mach; 196 if (exec_bfd == NULL) 197 error (_("Can't find default bfd machine type (need execfile).")); 198 199 return bfd_get_mach (exec_bfd); 200#endif /* 1 */ 201} 202 203static enum bfd_architecture 204default_gcore_arch (void) 205{ 206 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch ()); 207 208 if (bfdarch != NULL) 209 return bfdarch->arch; 210 if (exec_bfd == NULL) 211 error (_("Can't find bfd architecture for corefile (need execfile).")); 212 213 return bfd_get_arch (exec_bfd); 214} 215 216static const char * 217default_gcore_target (void) 218{ 219 /* The gdbarch may define a target to use for core files. */ 220 if (gdbarch_gcore_bfd_target_p (target_gdbarch ())) 221 return gdbarch_gcore_bfd_target (target_gdbarch ()); 222 223 /* Otherwise, try to fall back to the exec_bfd target. This will probably 224 not work for non-ELF targets. */ 225 if (exec_bfd == NULL) 226 return NULL; 227 else 228 return bfd_get_target (exec_bfd); 229} 230 231/* Derive a reasonable stack segment by unwinding the target stack, 232 and store its limits in *BOTTOM and *TOP. Return non-zero if 233 successful. */ 234 235static int 236derive_stack_segment (bfd_vma *bottom, bfd_vma *top) 237{ 238 struct frame_info *fi, *tmp_fi; 239 240 gdb_assert (bottom); 241 gdb_assert (top); 242 243 /* Can't succeed without stack and registers. */ 244 if (!target_has_stack || !target_has_registers) 245 return 0; 246 247 /* Can't succeed without current frame. */ 248 fi = get_current_frame (); 249 if (fi == NULL) 250 return 0; 251 252 /* Save frame pointer of TOS frame. */ 253 *top = get_frame_base (fi); 254 /* If current stack pointer is more "inner", use that instead. */ 255 if (gdbarch_inner_than (get_frame_arch (fi), get_frame_sp (fi), *top)) 256 *top = get_frame_sp (fi); 257 258 /* Find prev-most frame. */ 259 while ((tmp_fi = get_prev_frame (fi)) != NULL) 260 fi = tmp_fi; 261 262 /* Save frame pointer of prev-most frame. */ 263 *bottom = get_frame_base (fi); 264 265 /* Now canonicalize their order, so that BOTTOM is a lower address 266 (as opposed to a lower stack frame). */ 267 if (*bottom > *top) 268 { 269 bfd_vma tmp_vma; 270 271 tmp_vma = *top; 272 *top = *bottom; 273 *bottom = tmp_vma; 274 } 275 276 return 1; 277} 278 279/* call_target_sbrk -- 280 helper function for derive_heap_segment. */ 281 282static bfd_vma 283call_target_sbrk (int sbrk_arg) 284{ 285 struct objfile *sbrk_objf; 286 struct gdbarch *gdbarch; 287 bfd_vma top_of_heap; 288 struct value *target_sbrk_arg; 289 struct value *sbrk_fn, *ret; 290 bfd_vma tmp; 291 292 if (lookup_minimal_symbol ("sbrk", NULL, NULL).minsym != NULL) 293 { 294 sbrk_fn = find_function_in_inferior ("sbrk", &sbrk_objf); 295 if (sbrk_fn == NULL) 296 return (bfd_vma) 0; 297 } 298 else if (lookup_minimal_symbol ("_sbrk", NULL, NULL).minsym != NULL) 299 { 300 sbrk_fn = find_function_in_inferior ("_sbrk", &sbrk_objf); 301 if (sbrk_fn == NULL) 302 return (bfd_vma) 0; 303 } 304 else 305 return (bfd_vma) 0; 306 307 gdbarch = get_objfile_arch (sbrk_objf); 308 target_sbrk_arg = value_from_longest (builtin_type (gdbarch)->builtin_int, 309 sbrk_arg); 310 gdb_assert (target_sbrk_arg); 311 ret = call_function_by_hand (sbrk_fn, 1, &target_sbrk_arg); 312 if (ret == NULL) 313 return (bfd_vma) 0; 314 315 tmp = value_as_long (ret); 316 if ((LONGEST) tmp <= 0 || (LONGEST) tmp == 0xffffffff) 317 return (bfd_vma) 0; 318 319 top_of_heap = tmp; 320 return top_of_heap; 321} 322 323/* Derive a reasonable heap segment for ABFD by looking at sbrk and 324 the static data sections. Store its limits in *BOTTOM and *TOP. 325 Return non-zero if successful. */ 326 327static int 328derive_heap_segment (bfd *abfd, bfd_vma *bottom, bfd_vma *top) 329{ 330 bfd_vma top_of_data_memory = 0; 331 bfd_vma top_of_heap = 0; 332 bfd_size_type sec_size; 333 bfd_vma sec_vaddr; 334 asection *sec; 335 336 gdb_assert (bottom); 337 gdb_assert (top); 338 339 /* This function depends on being able to call a function in the 340 inferior. */ 341 if (!target_has_execution) 342 return 0; 343 344 /* The following code assumes that the link map is arranged as 345 follows (low to high addresses): 346 347 --------------------------------- 348 | text sections | 349 --------------------------------- 350 | data sections (including bss) | 351 --------------------------------- 352 | heap | 353 --------------------------------- */ 354 355 for (sec = abfd->sections; sec; sec = sec->next) 356 { 357 if (bfd_get_section_flags (abfd, sec) & SEC_DATA 358 || strcmp (".bss", bfd_section_name (abfd, sec)) == 0) 359 { 360 sec_vaddr = bfd_get_section_vma (abfd, sec); 361 sec_size = bfd_get_section_size (sec); 362 if (sec_vaddr + sec_size > top_of_data_memory) 363 top_of_data_memory = sec_vaddr + sec_size; 364 } 365 } 366 367 top_of_heap = call_target_sbrk (0); 368 if (top_of_heap == (bfd_vma) 0) 369 return 0; 370 371 /* Return results. */ 372 if (top_of_heap > top_of_data_memory) 373 { 374 *bottom = top_of_data_memory; 375 *top = top_of_heap; 376 return 1; 377 } 378 379 /* No additional heap space needs to be saved. */ 380 return 0; 381} 382 383static void 384make_output_phdrs (bfd *obfd, asection *osec, void *ignored) 385{ 386 int p_flags = 0; 387 int p_type = 0; 388 389 /* FIXME: these constants may only be applicable for ELF. */ 390 if (strncmp (bfd_section_name (obfd, osec), "load", 4) == 0) 391 p_type = PT_LOAD; 392 else if (strncmp (bfd_section_name (obfd, osec), "note", 4) == 0) 393 p_type = PT_NOTE; 394 else 395 p_type = PT_NULL; 396 397 p_flags |= PF_R; /* Segment is readable. */ 398 if (!(bfd_get_section_flags (obfd, osec) & SEC_READONLY)) 399 p_flags |= PF_W; /* Segment is writable. */ 400 if (bfd_get_section_flags (obfd, osec) & SEC_CODE) 401 p_flags |= PF_X; /* Segment is executable. */ 402 403 bfd_record_phdr (obfd, p_type, 1, p_flags, 0, 0, 0, 0, 1, &osec); 404} 405 406/* find_memory_region_ftype implementation. DATA is 'bfd *' for the core file 407 GDB is creating. */ 408 409static int 410gcore_create_callback (CORE_ADDR vaddr, unsigned long size, int read, 411 int write, int exec, int modified, void *data) 412{ 413 bfd *obfd = data; 414 asection *osec; 415 flagword flags = SEC_ALLOC | SEC_HAS_CONTENTS | SEC_LOAD; 416 417 /* If the memory segment has no permissions set, ignore it, otherwise 418 when we later try to access it for read/write, we'll get an error 419 or jam the kernel. */ 420 if (read == 0 && write == 0 && exec == 0 && modified == 0) 421 { 422 if (info_verbose) 423 { 424 fprintf_filtered (gdb_stdout, "Ignore segment, %s bytes at %s\n", 425 plongest (size), paddress (target_gdbarch (), vaddr)); 426 } 427 428 return 0; 429 } 430 431 if (write == 0 && modified == 0 && !solib_keep_data_in_core (vaddr, size)) 432 { 433 /* See if this region of memory lies inside a known file on disk. 434 If so, we can avoid copying its contents by clearing SEC_LOAD. */ 435 struct objfile *objfile; 436 struct obj_section *objsec; 437 438 ALL_OBJSECTIONS (objfile, objsec) 439 { 440 bfd *abfd = objfile->obfd; 441 asection *asec = objsec->the_bfd_section; 442 bfd_vma align = (bfd_vma) 1 << bfd_get_section_alignment (abfd, 443 asec); 444 bfd_vma start = obj_section_addr (objsec) & -align; 445 bfd_vma end = (obj_section_endaddr (objsec) + align - 1) & -align; 446 447 /* Match if either the entire memory region lies inside the 448 section (i.e. a mapping covering some pages of a large 449 segment) or the entire section lies inside the memory region 450 (i.e. a mapping covering multiple small sections). 451 452 This BFD was synthesized from reading target memory, 453 we don't want to omit that. */ 454 if (objfile->separate_debug_objfile_backlink == NULL 455 && ((vaddr >= start && vaddr + size <= end) 456 || (start >= vaddr && end <= vaddr + size)) 457 && !(bfd_get_file_flags (abfd) & BFD_IN_MEMORY)) 458 { 459 flags &= ~(SEC_LOAD | SEC_HAS_CONTENTS); 460 goto keep; /* Break out of two nested for loops. */ 461 } 462 } 463 464 keep:; 465 } 466 467 if (write == 0) 468 flags |= SEC_READONLY; 469 470 if (exec) 471 flags |= SEC_CODE; 472 else 473 flags |= SEC_DATA; 474 475 osec = bfd_make_section_anyway_with_flags (obfd, "load", flags); 476 if (osec == NULL) 477 { 478 warning (_("Couldn't make gcore segment: %s"), 479 bfd_errmsg (bfd_get_error ())); 480 return 1; 481 } 482 483 if (info_verbose) 484 { 485 fprintf_filtered (gdb_stdout, "Save segment, %s bytes at %s\n", 486 plongest (size), paddress (target_gdbarch (), vaddr)); 487 } 488 489 bfd_set_section_size (obfd, osec, size); 490 bfd_set_section_vma (obfd, osec, vaddr); 491 bfd_section_lma (obfd, osec) = 0; /* ??? bfd_set_section_lma? */ 492 return 0; 493} 494 495int 496objfile_find_memory_regions (struct target_ops *self, 497 find_memory_region_ftype func, void *obfd) 498{ 499 /* Use objfile data to create memory sections. */ 500 struct objfile *objfile; 501 struct obj_section *objsec; 502 bfd_vma temp_bottom, temp_top; 503 504 /* Call callback function for each objfile section. */ 505 ALL_OBJSECTIONS (objfile, objsec) 506 { 507 bfd *ibfd = objfile->obfd; 508 asection *isec = objsec->the_bfd_section; 509 flagword flags = bfd_get_section_flags (ibfd, isec); 510 511 /* Separate debug info files are irrelevant for gcore. */ 512 if (objfile->separate_debug_objfile_backlink != NULL) 513 continue; 514 515 if ((flags & SEC_ALLOC) || (flags & SEC_LOAD)) 516 { 517 int size = bfd_section_size (ibfd, isec); 518 int ret; 519 520 ret = (*func) (obj_section_addr (objsec), size, 521 1, /* All sections will be readable. */ 522 (flags & SEC_READONLY) == 0, /* Writable. */ 523 (flags & SEC_CODE) != 0, /* Executable. */ 524 1, /* MODIFIED is unknown, pass it as true. */ 525 obfd); 526 if (ret != 0) 527 return ret; 528 } 529 } 530 531 /* Make a stack segment. */ 532 if (derive_stack_segment (&temp_bottom, &temp_top)) 533 (*func) (temp_bottom, temp_top - temp_bottom, 534 1, /* Stack section will be readable. */ 535 1, /* Stack section will be writable. */ 536 0, /* Stack section will not be executable. */ 537 1, /* Stack section will be modified. */ 538 obfd); 539 540 /* Make a heap segment. */ 541 if (derive_heap_segment (exec_bfd, &temp_bottom, &temp_top)) 542 (*func) (temp_bottom, temp_top - temp_bottom, 543 1, /* Heap section will be readable. */ 544 1, /* Heap section will be writable. */ 545 0, /* Heap section will not be executable. */ 546 1, /* Heap section will be modified. */ 547 obfd); 548 549 return 0; 550} 551 552static void 553gcore_copy_callback (bfd *obfd, asection *osec, void *ignored) 554{ 555 bfd_size_type size, total_size = bfd_section_size (obfd, osec); 556 file_ptr offset = 0; 557 struct cleanup *old_chain = NULL; 558 void *memhunk; 559 560 /* Read-only sections are marked; we don't have to copy their contents. */ 561 if ((bfd_get_section_flags (obfd, osec) & SEC_LOAD) == 0) 562 return; 563 564 /* Only interested in "load" sections. */ 565 if (strncmp ("load", bfd_section_name (obfd, osec), 4) != 0) 566 return; 567 568 size = min (total_size, MAX_COPY_BYTES); 569 memhunk = xmalloc (size); 570 old_chain = make_cleanup (xfree, memhunk); 571 572 while (total_size > 0) 573 { 574 if (size > total_size) 575 size = total_size; 576 577 if (target_read_memory (bfd_section_vma (obfd, osec) + offset, 578 memhunk, size) != 0) 579 { 580 warning (_("Memory read failed for corefile " 581 "section, %s bytes at %s."), 582 plongest (size), 583 paddress (target_gdbarch (), bfd_section_vma (obfd, osec))); 584 break; 585 } 586 if (!bfd_set_section_contents (obfd, osec, memhunk, offset, size)) 587 { 588 warning (_("Failed to write corefile contents (%s)."), 589 bfd_errmsg (bfd_get_error ())); 590 break; 591 } 592 593 total_size -= size; 594 offset += size; 595 } 596 597 do_cleanups (old_chain); /* Frees MEMHUNK. */ 598} 599 600static int 601gcore_memory_sections (bfd *obfd) 602{ 603 /* Try gdbarch method first, then fall back to target method. */ 604 if (!gdbarch_find_memory_regions_p (target_gdbarch ()) 605 || gdbarch_find_memory_regions (target_gdbarch (), 606 gcore_create_callback, obfd) != 0) 607 { 608 if (target_find_memory_regions (gcore_create_callback, obfd) != 0) 609 return 0; /* FIXME: error return/msg? */ 610 } 611 612 /* Record phdrs for section-to-segment mapping. */ 613 bfd_map_over_sections (obfd, make_output_phdrs, NULL); 614 615 /* Copy memory region contents. */ 616 bfd_map_over_sections (obfd, gcore_copy_callback, NULL); 617 618 return 1; 619} 620 621/* Provide a prototype to silence -Wmissing-prototypes. */ 622extern initialize_file_ftype _initialize_gcore; 623 624void 625_initialize_gcore (void) 626{ 627 add_com ("generate-core-file", class_files, gcore_command, _("\ 628Save a core file with the current state of the debugged process.\n\ 629Argument is optional filename. Default filename is 'core.<process_id>'.")); 630 631 add_com_alias ("gcore", "generate-core-file", class_files, 1); 632} 633