1 /* Generate a core file for the inferior process. 2 3 Copyright (C) 2001-2013 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 #include "gdb_bfd.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 43 static const char *default_gcore_target (void); 44 static enum bfd_architecture default_gcore_arch (void); 45 static unsigned long default_gcore_mach (void); 46 static 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 51 bfd * 52 create_gcore_bfd (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 -- helper for gcore_command (exported). 64 Compose and write the corefile data to the core file. */ 65 66 67 void 68 write_gcore_file (bfd *obfd) 69 { 70 void *note_data = NULL; 71 int note_size = 0; 72 asection *note_sec = NULL; 73 74 /* An external target method must build the notes section. */ 75 /* FIXME: uweigand/2011-10-06: All architectures that support core file 76 generation should be converted to gdbarch_make_corefile_notes; at that 77 point, the target vector method can be removed. */ 78 if (!gdbarch_make_corefile_notes_p (target_gdbarch ())) 79 note_data = target_make_corefile_notes (obfd, ¬e_size); 80 else 81 note_data = gdbarch_make_corefile_notes (target_gdbarch (), obfd, ¬e_size); 82 83 if (note_data == NULL || note_size == 0) 84 error (_("Target does not support core file generation.")); 85 86 /* Create the note section. */ 87 note_sec = bfd_make_section_anyway_with_flags (obfd, "note0", 88 SEC_HAS_CONTENTS 89 | SEC_READONLY 90 | SEC_ALLOC); 91 if (note_sec == NULL) 92 error (_("Failed to create 'note' section for corefile: %s"), 93 bfd_errmsg (bfd_get_error ())); 94 95 bfd_set_section_vma (obfd, note_sec, 0); 96 bfd_set_section_alignment (obfd, note_sec, 0); 97 bfd_set_section_size (obfd, note_sec, note_size); 98 99 /* Now create the memory/load sections. */ 100 if (gcore_memory_sections (obfd) == 0) 101 error (_("gcore: failed to get corefile memory sections from target.")); 102 103 /* Write out the contents of the note section. */ 104 if (!bfd_set_section_contents (obfd, note_sec, note_data, 0, note_size)) 105 warning (_("writing note section (%s)"), bfd_errmsg (bfd_get_error ())); 106 } 107 108 static void 109 do_bfd_delete_cleanup (void *arg) 110 { 111 bfd *obfd = arg; 112 const char *filename = obfd->filename; 113 114 gdb_bfd_unref (arg); 115 unlink (filename); 116 } 117 118 /* gcore_command -- implements the 'gcore' command. 119 Generate a core file from the inferior process. */ 120 121 static void 122 gcore_command (char *args, int from_tty) 123 { 124 struct cleanup *old_chain; 125 char *corefilename, corefilename_buffer[40]; 126 bfd *obfd; 127 128 /* No use generating a corefile without a target process. */ 129 if (!target_has_execution) 130 noprocess (); 131 132 if (args && *args) 133 corefilename = args; 134 else 135 { 136 /* Default corefile name is "core.PID". */ 137 xsnprintf (corefilename_buffer, sizeof (corefilename_buffer), 138 "core.%d", PIDGET (inferior_ptid)); 139 corefilename = corefilename_buffer; 140 } 141 142 if (info_verbose) 143 fprintf_filtered (gdb_stdout, 144 "Opening corefile '%s' for output.\n", corefilename); 145 146 /* Open the output file. */ 147 obfd = create_gcore_bfd (corefilename); 148 149 /* Need a cleanup that will close and delete the file. */ 150 old_chain = make_cleanup (do_bfd_delete_cleanup, obfd); 151 152 /* Call worker function. */ 153 write_gcore_file (obfd); 154 155 /* Succeeded. */ 156 fprintf_filtered (gdb_stdout, "Saved corefile %s\n", corefilename); 157 158 discard_cleanups (old_chain); 159 gdb_bfd_unref (obfd); 160 } 161 162 static unsigned long 163 default_gcore_mach (void) 164 { 165 #if 1 /* See if this even matters... */ 166 return 0; 167 #else 168 169 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch ()); 170 171 if (bfdarch != NULL) 172 return bfdarch->mach; 173 if (exec_bfd == NULL) 174 error (_("Can't find default bfd machine type (need execfile).")); 175 176 return bfd_get_mach (exec_bfd); 177 #endif /* 1 */ 178 } 179 180 static enum bfd_architecture 181 default_gcore_arch (void) 182 { 183 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch ()); 184 185 if (bfdarch != NULL) 186 return bfdarch->arch; 187 if (exec_bfd == NULL) 188 error (_("Can't find bfd architecture for corefile (need execfile).")); 189 190 return bfd_get_arch (exec_bfd); 191 } 192 193 static const char * 194 default_gcore_target (void) 195 { 196 /* The gdbarch may define a target to use for core files. */ 197 if (gdbarch_gcore_bfd_target_p (target_gdbarch ())) 198 return gdbarch_gcore_bfd_target (target_gdbarch ()); 199 200 /* Otherwise, try to fall back to the exec_bfd target. This will probably 201 not work for non-ELF targets. */ 202 if (exec_bfd == NULL) 203 return NULL; 204 else 205 return bfd_get_target (exec_bfd); 206 } 207 208 /* Derive a reasonable stack segment by unwinding the target stack, 209 and store its limits in *BOTTOM and *TOP. Return non-zero if 210 successful. */ 211 212 static int 213 derive_stack_segment (bfd_vma *bottom, bfd_vma *top) 214 { 215 struct frame_info *fi, *tmp_fi; 216 217 gdb_assert (bottom); 218 gdb_assert (top); 219 220 /* Can't succeed without stack and registers. */ 221 if (!target_has_stack || !target_has_registers) 222 return 0; 223 224 /* Can't succeed without current frame. */ 225 fi = get_current_frame (); 226 if (fi == NULL) 227 return 0; 228 229 /* Save frame pointer of TOS frame. */ 230 *top = get_frame_base (fi); 231 /* If current stack pointer is more "inner", use that instead. */ 232 if (gdbarch_inner_than (get_frame_arch (fi), get_frame_sp (fi), *top)) 233 *top = get_frame_sp (fi); 234 235 /* Find prev-most frame. */ 236 while ((tmp_fi = get_prev_frame (fi)) != NULL) 237 fi = tmp_fi; 238 239 /* Save frame pointer of prev-most frame. */ 240 *bottom = get_frame_base (fi); 241 242 /* Now canonicalize their order, so that BOTTOM is a lower address 243 (as opposed to a lower stack frame). */ 244 if (*bottom > *top) 245 { 246 bfd_vma tmp_vma; 247 248 tmp_vma = *top; 249 *top = *bottom; 250 *bottom = tmp_vma; 251 } 252 253 return 1; 254 } 255 256 /* call_target_sbrk -- 257 helper function for derive_heap_segment. */ 258 259 static bfd_vma 260 call_target_sbrk (int sbrk_arg) 261 { 262 struct objfile *sbrk_objf; 263 struct gdbarch *gdbarch; 264 bfd_vma top_of_heap; 265 struct value *target_sbrk_arg; 266 struct value *sbrk_fn, *ret; 267 bfd_vma tmp; 268 269 if (lookup_minimal_symbol ("sbrk", NULL, NULL) != NULL) 270 { 271 sbrk_fn = find_function_in_inferior ("sbrk", &sbrk_objf); 272 if (sbrk_fn == NULL) 273 return (bfd_vma) 0; 274 } 275 else if (lookup_minimal_symbol ("_sbrk", NULL, NULL) != NULL) 276 { 277 sbrk_fn = find_function_in_inferior ("_sbrk", &sbrk_objf); 278 if (sbrk_fn == NULL) 279 return (bfd_vma) 0; 280 } 281 else 282 return (bfd_vma) 0; 283 284 gdbarch = get_objfile_arch (sbrk_objf); 285 target_sbrk_arg = value_from_longest (builtin_type (gdbarch)->builtin_int, 286 sbrk_arg); 287 gdb_assert (target_sbrk_arg); 288 ret = call_function_by_hand (sbrk_fn, 1, &target_sbrk_arg); 289 if (ret == NULL) 290 return (bfd_vma) 0; 291 292 tmp = value_as_long (ret); 293 if ((LONGEST) tmp <= 0 || (LONGEST) tmp == 0xffffffff) 294 return (bfd_vma) 0; 295 296 top_of_heap = tmp; 297 return top_of_heap; 298 } 299 300 /* Derive a reasonable heap segment for ABFD by looking at sbrk and 301 the static data sections. Store its limits in *BOTTOM and *TOP. 302 Return non-zero if successful. */ 303 304 static int 305 derive_heap_segment (bfd *abfd, bfd_vma *bottom, bfd_vma *top) 306 { 307 bfd_vma top_of_data_memory = 0; 308 bfd_vma top_of_heap = 0; 309 bfd_size_type sec_size; 310 bfd_vma sec_vaddr; 311 asection *sec; 312 313 gdb_assert (bottom); 314 gdb_assert (top); 315 316 /* This function depends on being able to call a function in the 317 inferior. */ 318 if (!target_has_execution) 319 return 0; 320 321 /* The following code assumes that the link map is arranged as 322 follows (low to high addresses): 323 324 --------------------------------- 325 | text sections | 326 --------------------------------- 327 | data sections (including bss) | 328 --------------------------------- 329 | heap | 330 --------------------------------- */ 331 332 for (sec = abfd->sections; sec; sec = sec->next) 333 { 334 if (bfd_get_section_flags (abfd, sec) & SEC_DATA 335 || strcmp (".bss", bfd_section_name (abfd, sec)) == 0) 336 { 337 sec_vaddr = bfd_get_section_vma (abfd, sec); 338 sec_size = bfd_get_section_size (sec); 339 if (sec_vaddr + sec_size > top_of_data_memory) 340 top_of_data_memory = sec_vaddr + sec_size; 341 } 342 } 343 344 top_of_heap = call_target_sbrk (0); 345 if (top_of_heap == (bfd_vma) 0) 346 return 0; 347 348 /* Return results. */ 349 if (top_of_heap > top_of_data_memory) 350 { 351 *bottom = top_of_data_memory; 352 *top = top_of_heap; 353 return 1; 354 } 355 356 /* No additional heap space needs to be saved. */ 357 return 0; 358 } 359 360 static void 361 make_output_phdrs (bfd *obfd, asection *osec, void *ignored) 362 { 363 int p_flags = 0; 364 int p_type = 0; 365 366 /* FIXME: these constants may only be applicable for ELF. */ 367 if (strncmp (bfd_section_name (obfd, osec), "load", 4) == 0) 368 p_type = PT_LOAD; 369 else if (strncmp (bfd_section_name (obfd, osec), "note", 4) == 0) 370 p_type = PT_NOTE; 371 else 372 p_type = PT_NULL; 373 374 p_flags |= PF_R; /* Segment is readable. */ 375 if (!(bfd_get_section_flags (obfd, osec) & SEC_READONLY)) 376 p_flags |= PF_W; /* Segment is writable. */ 377 if (bfd_get_section_flags (obfd, osec) & SEC_CODE) 378 p_flags |= PF_X; /* Segment is executable. */ 379 380 bfd_record_phdr (obfd, p_type, 1, p_flags, 0, 0, 0, 0, 1, &osec); 381 } 382 383 /* find_memory_region_ftype implementation. DATA is 'bfd *' for the core file 384 GDB is creating. */ 385 386 static int 387 gcore_create_callback (CORE_ADDR vaddr, unsigned long size, int read, 388 int write, int exec, int modified, void *data) 389 { 390 bfd *obfd = data; 391 asection *osec; 392 flagword flags = SEC_ALLOC | SEC_HAS_CONTENTS | SEC_LOAD; 393 394 /* If the memory segment has no permissions set, ignore it, otherwise 395 when we later try to access it for read/write, we'll get an error 396 or jam the kernel. */ 397 if (read == 0 && write == 0 && exec == 0 && modified == 0) 398 { 399 if (info_verbose) 400 { 401 fprintf_filtered (gdb_stdout, "Ignore segment, %s bytes at %s\n", 402 plongest (size), paddress (target_gdbarch (), vaddr)); 403 } 404 405 return 0; 406 } 407 408 if (write == 0 && modified == 0 && !solib_keep_data_in_core (vaddr, size)) 409 { 410 /* See if this region of memory lies inside a known file on disk. 411 If so, we can avoid copying its contents by clearing SEC_LOAD. */ 412 struct objfile *objfile; 413 struct obj_section *objsec; 414 415 ALL_OBJSECTIONS (objfile, objsec) 416 { 417 bfd *abfd = objfile->obfd; 418 asection *asec = objsec->the_bfd_section; 419 bfd_vma align = (bfd_vma) 1 << bfd_get_section_alignment (abfd, 420 asec); 421 bfd_vma start = obj_section_addr (objsec) & -align; 422 bfd_vma end = (obj_section_endaddr (objsec) + align - 1) & -align; 423 424 /* Match if either the entire memory region lies inside the 425 section (i.e. a mapping covering some pages of a large 426 segment) or the entire section lies inside the memory region 427 (i.e. a mapping covering multiple small sections). 428 429 This BFD was synthesized from reading target memory, 430 we don't want to omit that. */ 431 if (((vaddr >= start && vaddr + size <= end) 432 || (start >= vaddr && end <= vaddr + size)) 433 && !(bfd_get_file_flags (abfd) & BFD_IN_MEMORY)) 434 { 435 flags &= ~(SEC_LOAD | SEC_HAS_CONTENTS); 436 goto keep; /* Break out of two nested for loops. */ 437 } 438 } 439 440 keep:; 441 } 442 443 if (write == 0) 444 flags |= SEC_READONLY; 445 446 if (exec) 447 flags |= SEC_CODE; 448 else 449 flags |= SEC_DATA; 450 451 osec = bfd_make_section_anyway_with_flags (obfd, "load", flags); 452 if (osec == NULL) 453 { 454 warning (_("Couldn't make gcore segment: %s"), 455 bfd_errmsg (bfd_get_error ())); 456 return 1; 457 } 458 459 if (info_verbose) 460 { 461 fprintf_filtered (gdb_stdout, "Save segment, %s bytes at %s\n", 462 plongest (size), paddress (target_gdbarch (), vaddr)); 463 } 464 465 bfd_set_section_size (obfd, osec, size); 466 bfd_set_section_vma (obfd, osec, vaddr); 467 bfd_section_lma (obfd, osec) = 0; /* ??? bfd_set_section_lma? */ 468 return 0; 469 } 470 471 static int 472 objfile_find_memory_regions (find_memory_region_ftype func, void *obfd) 473 { 474 /* Use objfile data to create memory sections. */ 475 struct objfile *objfile; 476 struct obj_section *objsec; 477 bfd_vma temp_bottom, temp_top; 478 479 /* Call callback function for each objfile section. */ 480 ALL_OBJSECTIONS (objfile, objsec) 481 { 482 bfd *ibfd = objfile->obfd; 483 asection *isec = objsec->the_bfd_section; 484 flagword flags = bfd_get_section_flags (ibfd, isec); 485 486 /* Separate debug info files are irrelevant for gcore. */ 487 if (objfile->separate_debug_objfile_backlink != NULL) 488 continue; 489 490 if ((flags & SEC_ALLOC) || (flags & SEC_LOAD)) 491 { 492 int size = bfd_section_size (ibfd, isec); 493 int ret; 494 495 ret = (*func) (obj_section_addr (objsec), size, 496 1, /* All sections will be readable. */ 497 (flags & SEC_READONLY) == 0, /* Writable. */ 498 (flags & SEC_CODE) != 0, /* Executable. */ 499 1, /* MODIFIED is unknown, pass it as true. */ 500 obfd); 501 if (ret != 0) 502 return ret; 503 } 504 } 505 506 /* Make a stack segment. */ 507 if (derive_stack_segment (&temp_bottom, &temp_top)) 508 (*func) (temp_bottom, temp_top - temp_bottom, 509 1, /* Stack section will be readable. */ 510 1, /* Stack section will be writable. */ 511 0, /* Stack section will not be executable. */ 512 1, /* Stack section will be modified. */ 513 obfd); 514 515 /* Make a heap segment. */ 516 if (derive_heap_segment (exec_bfd, &temp_bottom, &temp_top)) 517 (*func) (temp_bottom, temp_top - temp_bottom, 518 1, /* Heap section will be readable. */ 519 1, /* Heap section will be writable. */ 520 0, /* Heap section will not be executable. */ 521 1, /* Heap section will be modified. */ 522 obfd); 523 524 return 0; 525 } 526 527 static void 528 gcore_copy_callback (bfd *obfd, asection *osec, void *ignored) 529 { 530 bfd_size_type size, total_size = bfd_section_size (obfd, osec); 531 file_ptr offset = 0; 532 struct cleanup *old_chain = NULL; 533 void *memhunk; 534 535 /* Read-only sections are marked; we don't have to copy their contents. */ 536 if ((bfd_get_section_flags (obfd, osec) & SEC_LOAD) == 0) 537 return; 538 539 /* Only interested in "load" sections. */ 540 if (strncmp ("load", bfd_section_name (obfd, osec), 4) != 0) 541 return; 542 543 size = min (total_size, MAX_COPY_BYTES); 544 memhunk = xmalloc (size); 545 old_chain = make_cleanup (xfree, memhunk); 546 547 while (total_size > 0) 548 { 549 if (size > total_size) 550 size = total_size; 551 552 if (target_read_memory (bfd_section_vma (obfd, osec) + offset, 553 memhunk, size) != 0) 554 { 555 warning (_("Memory read failed for corefile " 556 "section, %s bytes at %s."), 557 plongest (size), 558 paddress (target_gdbarch (), bfd_section_vma (obfd, osec))); 559 break; 560 } 561 if (!bfd_set_section_contents (obfd, osec, memhunk, offset, size)) 562 { 563 warning (_("Failed to write corefile contents (%s)."), 564 bfd_errmsg (bfd_get_error ())); 565 break; 566 } 567 568 total_size -= size; 569 offset += size; 570 } 571 572 do_cleanups (old_chain); /* Frees MEMHUNK. */ 573 } 574 575 static int 576 gcore_memory_sections (bfd *obfd) 577 { 578 /* Try gdbarch method first, then fall back to target method. */ 579 if (!gdbarch_find_memory_regions_p (target_gdbarch ()) 580 || gdbarch_find_memory_regions (target_gdbarch (), 581 gcore_create_callback, obfd) != 0) 582 { 583 if (target_find_memory_regions (gcore_create_callback, obfd) != 0) 584 return 0; /* FIXME: error return/msg? */ 585 } 586 587 /* Record phdrs for section-to-segment mapping. */ 588 bfd_map_over_sections (obfd, make_output_phdrs, NULL); 589 590 /* Copy memory region contents. */ 591 bfd_map_over_sections (obfd, gcore_copy_callback, NULL); 592 593 return 1; 594 } 595 596 /* Provide a prototype to silence -Wmissing-prototypes. */ 597 extern initialize_file_ftype _initialize_gcore; 598 599 void 600 _initialize_gcore (void) 601 { 602 add_com ("generate-core-file", class_files, gcore_command, _("\ 603 Save a core file with the current state of the debugged process.\n\ 604 Argument is optional filename. Default filename is 'core.<process_id>'.")); 605 606 add_com_alias ("gcore", "generate-core-file", class_files, 1); 607 exec_set_find_memory_regions (objfile_find_memory_regions); 608 } 609