1 /* Generate a core file for the inferior process. 2 3 Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 4 Free Software Foundation, Inc. 5 6 This file is part of GDB. 7 8 This program is free software; you can redistribute it and/or modify 9 it under the terms of the GNU General Public License as published by 10 the Free Software Foundation; either version 3 of the License, or 11 (at your option) any later version. 12 13 This program is distributed in the hope that it will be useful, 14 but WITHOUT ANY WARRANTY; without even the implied warranty of 15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 GNU General Public License for more details. 17 18 You should have received a copy of the GNU General Public License 19 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 20 21 #include "defs.h" 22 #include "elf-bfd.h" 23 #include "infcall.h" 24 #include "inferior.h" 25 #include "gdbcore.h" 26 #include "objfiles.h" 27 #include "solib.h" 28 #include "symfile.h" 29 #include "arch-utils.h" 30 #include "completer.h" 31 #include "gcore.h" 32 #include "cli/cli-decode.h" 33 #include "gdb_assert.h" 34 #include <fcntl.h> 35 #include "regcache.h" 36 #include "regset.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 = 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 note_data = target_make_corefile_notes (obfd, ¬e_size); 76 77 /* Create the note section. */ 78 if (note_data != NULL && note_size != 0) 79 { 80 note_sec = bfd_make_section_anyway_with_flags (obfd, "note0", 81 SEC_HAS_CONTENTS 82 | SEC_READONLY 83 | SEC_ALLOC); 84 if (note_sec == NULL) 85 error (_("Failed to create 'note' section for corefile: %s"), 86 bfd_errmsg (bfd_get_error ())); 87 88 bfd_set_section_vma (obfd, note_sec, 0); 89 bfd_set_section_alignment (obfd, note_sec, 0); 90 bfd_set_section_size (obfd, note_sec, note_size); 91 } 92 93 /* Now create the memory/load sections. */ 94 if (gcore_memory_sections (obfd) == 0) 95 error (_("gcore: failed to get corefile memory sections from target.")); 96 97 /* Write out the contents of the note section. */ 98 if (note_data != NULL && note_size != 0) 99 { 100 if (!bfd_set_section_contents (obfd, note_sec, note_data, 0, note_size)) 101 warning (_("writing note section (%s)"), 102 bfd_errmsg (bfd_get_error ())); 103 } 104 } 105 106 static void 107 do_bfd_delete_cleanup (void *arg) 108 { 109 bfd *obfd = arg; 110 const char *filename = obfd->filename; 111 112 bfd_close (arg); 113 unlink (filename); 114 } 115 116 /* gcore_command -- implements the 'gcore' command. 117 Generate a core file from the inferior process. */ 118 119 static void 120 gcore_command (char *args, int from_tty) 121 { 122 struct cleanup *old_chain; 123 char *corefilename, corefilename_buffer[40]; 124 bfd *obfd; 125 126 /* No use generating a corefile without a target process. */ 127 if (!target_has_execution) 128 noprocess (); 129 130 if (args && *args) 131 corefilename = args; 132 else 133 { 134 /* Default corefile name is "core.PID". */ 135 sprintf (corefilename_buffer, "core.%d", PIDGET (inferior_ptid)); 136 corefilename = corefilename_buffer; 137 } 138 139 if (info_verbose) 140 fprintf_filtered (gdb_stdout, 141 "Opening corefile '%s' for output.\n", corefilename); 142 143 /* Open the output file. */ 144 obfd = create_gcore_bfd (corefilename); 145 146 /* Need a cleanup that will close and delete the file. */ 147 old_chain = make_cleanup (do_bfd_delete_cleanup, obfd); 148 149 /* Call worker function. */ 150 write_gcore_file (obfd); 151 152 /* Succeeded. */ 153 fprintf_filtered (gdb_stdout, "Saved corefile %s\n", corefilename); 154 155 discard_cleanups (old_chain); 156 bfd_close (obfd); 157 } 158 159 static unsigned long 160 default_gcore_mach (void) 161 { 162 #if 1 /* See if this even matters... */ 163 return 0; 164 #else 165 166 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch); 167 168 if (bfdarch != NULL) 169 return bfdarch->mach; 170 if (exec_bfd == NULL) 171 error (_("Can't find default bfd machine type (need execfile).")); 172 173 return bfd_get_mach (exec_bfd); 174 #endif /* 1 */ 175 } 176 177 static enum bfd_architecture 178 default_gcore_arch (void) 179 { 180 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch); 181 182 if (bfdarch != NULL) 183 return bfdarch->arch; 184 if (exec_bfd == NULL) 185 error (_("Can't find bfd architecture for corefile (need execfile).")); 186 187 return bfd_get_arch (exec_bfd); 188 } 189 190 static const char * 191 default_gcore_target (void) 192 { 193 /* The gdbarch may define a target to use for core files. */ 194 if (gdbarch_gcore_bfd_target_p (target_gdbarch)) 195 return gdbarch_gcore_bfd_target (target_gdbarch); 196 197 /* Otherwise, try to fall back to the exec_bfd target. This will probably 198 not work for non-ELF targets. */ 199 if (exec_bfd == NULL) 200 return NULL; 201 else 202 return bfd_get_target (exec_bfd); 203 } 204 205 /* Derive a reasonable stack segment by unwinding the target stack, 206 and store its limits in *BOTTOM and *TOP. Return non-zero if 207 successful. */ 208 209 static int 210 derive_stack_segment (bfd_vma *bottom, bfd_vma *top) 211 { 212 struct frame_info *fi, *tmp_fi; 213 214 gdb_assert (bottom); 215 gdb_assert (top); 216 217 /* Can't succeed without stack and registers. */ 218 if (!target_has_stack || !target_has_registers) 219 return 0; 220 221 /* Can't succeed without current frame. */ 222 fi = get_current_frame (); 223 if (fi == NULL) 224 return 0; 225 226 /* Save frame pointer of TOS frame. */ 227 *top = get_frame_base (fi); 228 /* If current stack pointer is more "inner", use that instead. */ 229 if (gdbarch_inner_than (get_frame_arch (fi), get_frame_sp (fi), *top)) 230 *top = get_frame_sp (fi); 231 232 /* Find prev-most frame. */ 233 while ((tmp_fi = get_prev_frame (fi)) != NULL) 234 fi = tmp_fi; 235 236 /* Save frame pointer of prev-most frame. */ 237 *bottom = get_frame_base (fi); 238 239 /* Now canonicalize their order, so that BOTTOM is a lower address 240 (as opposed to a lower stack frame). */ 241 if (*bottom > *top) 242 { 243 bfd_vma tmp_vma; 244 245 tmp_vma = *top; 246 *top = *bottom; 247 *bottom = tmp_vma; 248 } 249 250 return 1; 251 } 252 253 /* call_target_sbrk -- 254 helper function for derive_heap_segment. */ 255 256 static bfd_vma 257 call_target_sbrk (int sbrk_arg) 258 { 259 struct objfile *sbrk_objf; 260 struct gdbarch *gdbarch; 261 bfd_vma top_of_heap; 262 struct value *target_sbrk_arg; 263 struct value *sbrk_fn, *ret; 264 bfd_vma tmp; 265 266 if (lookup_minimal_symbol ("sbrk", NULL, NULL) != NULL) 267 { 268 sbrk_fn = find_function_in_inferior ("sbrk", &sbrk_objf); 269 if (sbrk_fn == NULL) 270 return (bfd_vma) 0; 271 } 272 else if (lookup_minimal_symbol ("_sbrk", NULL, NULL) != NULL) 273 { 274 sbrk_fn = find_function_in_inferior ("_sbrk", &sbrk_objf); 275 if (sbrk_fn == NULL) 276 return (bfd_vma) 0; 277 } 278 else 279 return (bfd_vma) 0; 280 281 gdbarch = get_objfile_arch (sbrk_objf); 282 target_sbrk_arg = value_from_longest (builtin_type (gdbarch)->builtin_int, 283 sbrk_arg); 284 gdb_assert (target_sbrk_arg); 285 ret = call_function_by_hand (sbrk_fn, 1, &target_sbrk_arg); 286 if (ret == NULL) 287 return (bfd_vma) 0; 288 289 tmp = value_as_long (ret); 290 if ((LONGEST) tmp <= 0 || (LONGEST) tmp == 0xffffffff) 291 return (bfd_vma) 0; 292 293 top_of_heap = tmp; 294 return top_of_heap; 295 } 296 297 /* Derive a reasonable heap segment for ABFD by looking at sbrk and 298 the static data sections. Store its limits in *BOTTOM and *TOP. 299 Return non-zero if successful. */ 300 301 static int 302 derive_heap_segment (bfd *abfd, bfd_vma *bottom, bfd_vma *top) 303 { 304 bfd_vma top_of_data_memory = 0; 305 bfd_vma top_of_heap = 0; 306 bfd_size_type sec_size; 307 bfd_vma sec_vaddr; 308 asection *sec; 309 310 gdb_assert (bottom); 311 gdb_assert (top); 312 313 /* This function depends on being able to call a function in the 314 inferior. */ 315 if (!target_has_execution) 316 return 0; 317 318 /* The following code assumes that the link map is arranged as 319 follows (low to high addresses): 320 321 --------------------------------- 322 | text sections | 323 --------------------------------- 324 | data sections (including bss) | 325 --------------------------------- 326 | heap | 327 --------------------------------- */ 328 329 for (sec = abfd->sections; sec; sec = sec->next) 330 { 331 if (bfd_get_section_flags (abfd, sec) & SEC_DATA 332 || strcmp (".bss", bfd_section_name (abfd, sec)) == 0) 333 { 334 sec_vaddr = bfd_get_section_vma (abfd, sec); 335 sec_size = bfd_get_section_size (sec); 336 if (sec_vaddr + sec_size > top_of_data_memory) 337 top_of_data_memory = sec_vaddr + sec_size; 338 } 339 } 340 341 top_of_heap = call_target_sbrk (0); 342 if (top_of_heap == (bfd_vma) 0) 343 return 0; 344 345 /* Return results. */ 346 if (top_of_heap > top_of_data_memory) 347 { 348 *bottom = top_of_data_memory; 349 *top = top_of_heap; 350 return 1; 351 } 352 353 /* No additional heap space needs to be saved. */ 354 return 0; 355 } 356 357 static void 358 make_output_phdrs (bfd *obfd, asection *osec, void *ignored) 359 { 360 int p_flags = 0; 361 int p_type = 0; 362 363 /* FIXME: these constants may only be applicable for ELF. */ 364 if (strncmp (bfd_section_name (obfd, osec), "load", 4) == 0) 365 p_type = PT_LOAD; 366 else if (strncmp (bfd_section_name (obfd, osec), "note", 4) == 0) 367 p_type = PT_NOTE; 368 else 369 p_type = PT_NULL; 370 371 p_flags |= PF_R; /* Segment is readable. */ 372 if (!(bfd_get_section_flags (obfd, osec) & SEC_READONLY)) 373 p_flags |= PF_W; /* Segment is writable. */ 374 if (bfd_get_section_flags (obfd, osec) & SEC_CODE) 375 p_flags |= PF_X; /* Segment is executable. */ 376 377 bfd_record_phdr (obfd, p_type, 1, p_flags, 0, 0, 0, 0, 1, &osec); 378 } 379 380 static int 381 gcore_create_callback (CORE_ADDR vaddr, unsigned long size, 382 int read, int write, int exec, void *data) 383 { 384 bfd *obfd = data; 385 asection *osec; 386 flagword flags = SEC_ALLOC | SEC_HAS_CONTENTS | SEC_LOAD; 387 388 /* If the memory segment has no permissions set, ignore it, otherwise 389 when we later try to access it for read/write, we'll get an error 390 or jam the kernel. */ 391 if (read == 0 && write == 0 && exec == 0) 392 { 393 if (info_verbose) 394 { 395 fprintf_filtered (gdb_stdout, "Ignore segment, %s bytes at %s\n", 396 plongest (size), paddress (target_gdbarch, vaddr)); 397 } 398 399 return 0; 400 } 401 402 if (write == 0 && !solib_keep_data_in_core (vaddr, size)) 403 { 404 /* See if this region of memory lies inside a known file on disk. 405 If so, we can avoid copying its contents by clearing SEC_LOAD. */ 406 struct objfile *objfile; 407 struct obj_section *objsec; 408 409 ALL_OBJSECTIONS (objfile, objsec) 410 { 411 bfd *abfd = objfile->obfd; 412 asection *asec = objsec->the_bfd_section; 413 bfd_vma align = (bfd_vma) 1 << bfd_get_section_alignment (abfd, 414 asec); 415 bfd_vma start = obj_section_addr (objsec) & -align; 416 bfd_vma end = (obj_section_endaddr (objsec) + align - 1) & -align; 417 418 /* Match if either the entire memory region lies inside the 419 section (i.e. a mapping covering some pages of a large 420 segment) or the entire section lies inside the memory region 421 (i.e. a mapping covering multiple small sections). 422 423 This BFD was synthesized from reading target memory, 424 we don't want to omit that. */ 425 if (((vaddr >= start && vaddr + size <= end) 426 || (start >= vaddr && end <= vaddr + size)) 427 && !(bfd_get_file_flags (abfd) & BFD_IN_MEMORY)) 428 { 429 flags &= ~SEC_LOAD; 430 flags |= SEC_NEVER_LOAD; 431 goto keep; /* break out of two nested for loops */ 432 } 433 } 434 435 keep: 436 flags |= SEC_READONLY; 437 } 438 439 if (exec) 440 flags |= SEC_CODE; 441 else 442 flags |= SEC_DATA; 443 444 osec = bfd_make_section_anyway_with_flags (obfd, "load", flags); 445 if (osec == NULL) 446 { 447 warning (_("Couldn't make gcore segment: %s"), 448 bfd_errmsg (bfd_get_error ())); 449 return 1; 450 } 451 452 if (info_verbose) 453 { 454 fprintf_filtered (gdb_stdout, "Save segment, %s bytes at %s\n", 455 plongest (size), paddress (target_gdbarch, vaddr)); 456 } 457 458 bfd_set_section_size (obfd, osec, size); 459 bfd_set_section_vma (obfd, osec, vaddr); 460 bfd_section_lma (obfd, osec) = 0; /* ??? bfd_set_section_lma? */ 461 return 0; 462 } 463 464 static int 465 objfile_find_memory_regions (int (*func) (CORE_ADDR, unsigned long, 466 int, int, int, void *), 467 void *obfd) 468 { 469 /* Use objfile data to create memory sections. */ 470 struct objfile *objfile; 471 struct obj_section *objsec; 472 bfd_vma temp_bottom, temp_top; 473 474 /* Call callback function for each objfile section. */ 475 ALL_OBJSECTIONS (objfile, objsec) 476 { 477 bfd *ibfd = objfile->obfd; 478 asection *isec = objsec->the_bfd_section; 479 flagword flags = bfd_get_section_flags (ibfd, isec); 480 481 if ((flags & SEC_ALLOC) || (flags & SEC_LOAD)) 482 { 483 int size = bfd_section_size (ibfd, isec); 484 int ret; 485 486 ret = (*func) (obj_section_addr (objsec), size, 487 1, /* All sections will be readable. */ 488 (flags & SEC_READONLY) == 0, /* Writable. */ 489 (flags & SEC_CODE) != 0, /* Executable. */ 490 obfd); 491 if (ret != 0) 492 return ret; 493 } 494 } 495 496 /* Make a stack segment. */ 497 if (derive_stack_segment (&temp_bottom, &temp_top)) 498 (*func) (temp_bottom, temp_top - temp_bottom, 499 1, /* Stack section will be readable. */ 500 1, /* Stack section will be writable. */ 501 0, /* Stack section will not be executable. */ 502 obfd); 503 504 /* Make a heap segment. */ 505 if (derive_heap_segment (exec_bfd, &temp_bottom, &temp_top)) 506 (*func) (temp_bottom, temp_top - temp_bottom, 507 1, /* Heap section will be readable. */ 508 1, /* Heap section will be writable. */ 509 0, /* Heap section will not be executable. */ 510 obfd); 511 512 return 0; 513 } 514 515 static void 516 gcore_copy_callback (bfd *obfd, asection *osec, void *ignored) 517 { 518 bfd_size_type size, total_size = bfd_section_size (obfd, osec); 519 file_ptr offset = 0; 520 struct cleanup *old_chain = NULL; 521 void *memhunk; 522 523 /* Read-only sections are marked; we don't have to copy their contents. */ 524 if ((bfd_get_section_flags (obfd, osec) & SEC_LOAD) == 0) 525 return; 526 527 /* Only interested in "load" sections. */ 528 if (strncmp ("load", bfd_section_name (obfd, osec), 4) != 0) 529 return; 530 531 size = min (total_size, MAX_COPY_BYTES); 532 memhunk = xmalloc (size); 533 old_chain = make_cleanup (xfree, memhunk); 534 535 while (total_size > 0) 536 { 537 if (size > total_size) 538 size = total_size; 539 540 if (target_read_memory (bfd_section_vma (obfd, osec) + offset, 541 memhunk, size) != 0) 542 { 543 warning (_("Memory read failed for corefile section, %s bytes at %s."), 544 plongest (size), 545 paddress (target_gdbarch, bfd_section_vma (obfd, osec))); 546 break; 547 } 548 if (!bfd_set_section_contents (obfd, osec, memhunk, offset, size)) 549 { 550 warning (_("Failed to write corefile contents (%s)."), 551 bfd_errmsg (bfd_get_error ())); 552 break; 553 } 554 555 total_size -= size; 556 offset += size; 557 } 558 559 do_cleanups (old_chain); /* Frees MEMHUNK. */ 560 } 561 562 static int 563 gcore_memory_sections (bfd *obfd) 564 { 565 if (target_find_memory_regions (gcore_create_callback, obfd) != 0) 566 return 0; /* FIXME: error return/msg? */ 567 568 /* Record phdrs for section-to-segment mapping. */ 569 bfd_map_over_sections (obfd, make_output_phdrs, NULL); 570 571 /* Copy memory region contents. */ 572 bfd_map_over_sections (obfd, gcore_copy_callback, NULL); 573 574 return 1; 575 } 576 577 /* Provide a prototype to silence -Wmissing-prototypes. */ 578 extern initialize_file_ftype _initialize_gcore; 579 580 void 581 _initialize_gcore (void) 582 { 583 add_com ("generate-core-file", class_files, gcore_command, _("\ 584 Save a core file with the current state of the debugged process.\n\ 585 Argument is optional filename. Default filename is 'core.<process_id>'.")); 586 587 add_com_alias ("gcore", "generate-core-file", class_files, 1); 588 exec_set_find_memory_regions (objfile_find_memory_regions); 589 } 590