1 /* Generate a core file for the inferior process.
3 Copyright (C) 2001-2016 Free Software Foundation, Inc.
5 This file is part of GDB.
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.
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.
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/>. */
28 #include "arch-utils.h"
29 #include "completer.h"
31 #include "cli/cli-decode.h"
36 #include "readline/tilde.h"
39 /* The largest amount of memory to read from the target at once. We
40 must throttle it to limit the amount of memory used by GDB during
41 generate-core-file for programs with large resident data. */
42 #define MAX_COPY_BYTES (1024 * 1024)
44 static const char *default_gcore_target (void);
45 static enum bfd_architecture default_gcore_arch (void);
46 static unsigned long default_gcore_mach (void);
47 static int gcore_memory_sections (bfd *);
49 /* create_gcore_bfd -- helper for gcore_command (exported).
50 Open a new bfd core file for output, and return the handle. */
53 create_gcore_bfd (const char *filename)
55 bfd *obfd = gdb_bfd_openw (filename, default_gcore_target ());
58 error (_("Failed to open '%s' for output."), filename);
59 bfd_set_format (obfd, bfd_core);
60 bfd_set_arch_mach (obfd, default_gcore_arch (), default_gcore_mach ());
64 /* write_gcore_file_1 -- do the actual work of write_gcore_file. */
67 write_gcore_file_1 (bfd *obfd)
69 struct cleanup *cleanup;
70 void *note_data = NULL;
72 asection *note_sec = NULL;
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);
81 note_data = gdbarch_make_corefile_notes (target_gdbarch (), obfd, ¬e_size);
83 cleanup = make_cleanup (xfree, note_data);
85 if (note_data == NULL || note_size == 0)
86 error (_("Target does not support core file generation."));
88 /* Create the note section. */
89 note_sec = bfd_make_section_anyway_with_flags (obfd, "note0",
94 error (_("Failed to create 'note' section for corefile: %s"),
95 bfd_errmsg (bfd_get_error ()));
97 bfd_set_section_vma (obfd, note_sec, 0);
98 bfd_set_section_alignment (obfd, note_sec, 0);
99 bfd_set_section_size (obfd, note_sec, note_size);
101 /* Now create the memory/load sections. */
102 if (gcore_memory_sections (obfd) == 0)
103 error (_("gcore: failed to get corefile memory sections from target."));
105 /* Write out the contents of the note section. */
106 if (!bfd_set_section_contents (obfd, note_sec, note_data, 0, note_size))
107 warning (_("writing note section (%s)"), bfd_errmsg (bfd_get_error ()));
109 do_cleanups (cleanup);
112 /* write_gcore_file -- helper for gcore_command (exported).
113 Compose and write the corefile data to the core file. */
116 write_gcore_file (bfd *obfd)
118 struct gdb_exception except = exception_none;
120 target_prepare_to_generate_core ();
124 write_gcore_file_1 (obfd);
126 CATCH (e, RETURN_MASK_ALL)
132 target_done_generating_core ();
134 if (except.reason < 0)
135 throw_exception (except);
139 do_bfd_delete_cleanup (void *arg)
141 bfd *obfd = (bfd *) arg;
142 const char *filename = obfd->filename;
144 gdb_bfd_unref ((bfd *) arg);
148 /* gcore_command -- implements the 'gcore' command.
149 Generate a core file from the inferior process. */
152 gcore_command (char *args, int from_tty)
154 struct cleanup *filename_chain;
155 struct cleanup *bfd_chain;
159 /* No use generating a corefile without a target process. */
160 if (!target_has_execution)
164 corefilename = tilde_expand (args);
167 /* Default corefile name is "core.PID". */
168 corefilename = xstrprintf ("core.%d", ptid_get_pid (inferior_ptid));
170 filename_chain = make_cleanup (xfree, corefilename);
173 fprintf_filtered (gdb_stdout,
174 "Opening corefile '%s' for output.\n", corefilename);
176 /* Open the output file. */
177 obfd = create_gcore_bfd (corefilename);
179 /* Need a cleanup that will close and delete the file. */
180 bfd_chain = make_cleanup (do_bfd_delete_cleanup, obfd);
182 /* Call worker function. */
183 write_gcore_file (obfd);
186 discard_cleanups (bfd_chain);
187 gdb_bfd_unref (obfd);
189 fprintf_filtered (gdb_stdout, "Saved corefile %s\n", corefilename);
190 do_cleanups (filename_chain);
194 default_gcore_mach (void)
196 #if 1 /* See if this even matters... */
200 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch ());
203 return bfdarch->mach;
204 if (exec_bfd == NULL)
205 error (_("Can't find default bfd machine type (need execfile)."));
207 return bfd_get_mach (exec_bfd);
211 static enum bfd_architecture
212 default_gcore_arch (void)
214 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch ());
217 return bfdarch->arch;
218 if (exec_bfd == NULL)
219 error (_("Can't find bfd architecture for corefile (need execfile)."));
221 return bfd_get_arch (exec_bfd);
225 default_gcore_target (void)
227 /* The gdbarch may define a target to use for core files. */
228 if (gdbarch_gcore_bfd_target_p (target_gdbarch ()))
229 return gdbarch_gcore_bfd_target (target_gdbarch ());
231 /* Otherwise, try to fall back to the exec_bfd target. This will probably
232 not work for non-ELF targets. */
233 if (exec_bfd == NULL)
236 return bfd_get_target (exec_bfd);
239 /* Derive a reasonable stack segment by unwinding the target stack,
240 and store its limits in *BOTTOM and *TOP. Return non-zero if
244 derive_stack_segment (bfd_vma *bottom, bfd_vma *top)
246 struct frame_info *fi, *tmp_fi;
251 /* Can't succeed without stack and registers. */
252 if (!target_has_stack || !target_has_registers)
255 /* Can't succeed without current frame. */
256 fi = get_current_frame ();
260 /* Save frame pointer of TOS frame. */
261 *top = get_frame_base (fi);
262 /* If current stack pointer is more "inner", use that instead. */
263 if (gdbarch_inner_than (get_frame_arch (fi), get_frame_sp (fi), *top))
264 *top = get_frame_sp (fi);
266 /* Find prev-most frame. */
267 while ((tmp_fi = get_prev_frame (fi)) != NULL)
270 /* Save frame pointer of prev-most frame. */
271 *bottom = get_frame_base (fi);
273 /* Now canonicalize their order, so that BOTTOM is a lower address
274 (as opposed to a lower stack frame). */
287 /* call_target_sbrk --
288 helper function for derive_heap_segment. */
291 call_target_sbrk (int sbrk_arg)
293 struct objfile *sbrk_objf;
294 struct gdbarch *gdbarch;
296 struct value *target_sbrk_arg;
297 struct value *sbrk_fn, *ret;
300 if (lookup_minimal_symbol ("sbrk", NULL, NULL).minsym != NULL)
302 sbrk_fn = find_function_in_inferior ("sbrk", &sbrk_objf);
306 else if (lookup_minimal_symbol ("_sbrk", NULL, NULL).minsym != NULL)
308 sbrk_fn = find_function_in_inferior ("_sbrk", &sbrk_objf);
315 gdbarch = get_objfile_arch (sbrk_objf);
316 target_sbrk_arg = value_from_longest (builtin_type (gdbarch)->builtin_int,
318 gdb_assert (target_sbrk_arg);
319 ret = call_function_by_hand (sbrk_fn, 1, &target_sbrk_arg);
323 tmp = value_as_long (ret);
324 if ((LONGEST) tmp <= 0 || (LONGEST) tmp == 0xffffffff)
331 /* Derive a reasonable heap segment for ABFD by looking at sbrk and
332 the static data sections. Store its limits in *BOTTOM and *TOP.
333 Return non-zero if successful. */
336 derive_heap_segment (bfd *abfd, bfd_vma *bottom, bfd_vma *top)
338 bfd_vma top_of_data_memory = 0;
339 bfd_vma top_of_heap = 0;
340 bfd_size_type sec_size;
347 /* This function depends on being able to call a function in the
349 if (!target_has_execution)
352 /* The following code assumes that the link map is arranged as
353 follows (low to high addresses):
355 ---------------------------------
357 ---------------------------------
358 | data sections (including bss) |
359 ---------------------------------
361 --------------------------------- */
363 for (sec = abfd->sections; sec; sec = sec->next)
365 if (bfd_get_section_flags (abfd, sec) & SEC_DATA
366 || strcmp (".bss", bfd_section_name (abfd, sec)) == 0)
368 sec_vaddr = bfd_get_section_vma (abfd, sec);
369 sec_size = bfd_get_section_size (sec);
370 if (sec_vaddr + sec_size > top_of_data_memory)
371 top_of_data_memory = sec_vaddr + sec_size;
375 top_of_heap = call_target_sbrk (0);
376 if (top_of_heap == (bfd_vma) 0)
379 /* Return results. */
380 if (top_of_heap > top_of_data_memory)
382 *bottom = top_of_data_memory;
387 /* No additional heap space needs to be saved. */
392 make_output_phdrs (bfd *obfd, asection *osec, void *ignored)
397 /* FIXME: these constants may only be applicable for ELF. */
398 if (startswith (bfd_section_name (obfd, osec), "load"))
400 else if (startswith (bfd_section_name (obfd, osec), "note"))
405 p_flags |= PF_R; /* Segment is readable. */
406 if (!(bfd_get_section_flags (obfd, osec) & SEC_READONLY))
407 p_flags |= PF_W; /* Segment is writable. */
408 if (bfd_get_section_flags (obfd, osec) & SEC_CODE)
409 p_flags |= PF_X; /* Segment is executable. */
411 bfd_record_phdr (obfd, p_type, 1, p_flags, 0, 0, 0, 0, 1, &osec);
414 /* find_memory_region_ftype implementation. DATA is 'bfd *' for the core file
418 gcore_create_callback (CORE_ADDR vaddr, unsigned long size, int read,
419 int write, int exec, int modified, void *data)
421 bfd *obfd = (bfd *) data;
423 flagword flags = SEC_ALLOC | SEC_HAS_CONTENTS | SEC_LOAD;
425 /* If the memory segment has no permissions set, ignore it, otherwise
426 when we later try to access it for read/write, we'll get an error
427 or jam the kernel. */
428 if (read == 0 && write == 0 && exec == 0 && modified == 0)
432 fprintf_filtered (gdb_stdout, "Ignore segment, %s bytes at %s\n",
433 plongest (size), paddress (target_gdbarch (), vaddr));
439 if (write == 0 && modified == 0 && !solib_keep_data_in_core (vaddr, size))
441 /* See if this region of memory lies inside a known file on disk.
442 If so, we can avoid copying its contents by clearing SEC_LOAD. */
443 struct objfile *objfile;
444 struct obj_section *objsec;
446 ALL_OBJSECTIONS (objfile, objsec)
448 bfd *abfd = objfile->obfd;
449 asection *asec = objsec->the_bfd_section;
450 bfd_vma align = (bfd_vma) 1 << bfd_get_section_alignment (abfd,
452 bfd_vma start = obj_section_addr (objsec) & -align;
453 bfd_vma end = (obj_section_endaddr (objsec) + align - 1) & -align;
455 /* Match if either the entire memory region lies inside the
456 section (i.e. a mapping covering some pages of a large
457 segment) or the entire section lies inside the memory region
458 (i.e. a mapping covering multiple small sections).
460 This BFD was synthesized from reading target memory,
461 we don't want to omit that. */
462 if (objfile->separate_debug_objfile_backlink == NULL
463 && ((vaddr >= start && vaddr + size <= end)
464 || (start >= vaddr && end <= vaddr + size))
465 && !(bfd_get_file_flags (abfd) & BFD_IN_MEMORY))
467 flags &= ~(SEC_LOAD | SEC_HAS_CONTENTS);
468 goto keep; /* Break out of two nested for loops. */
476 flags |= SEC_READONLY;
483 osec = bfd_make_section_anyway_with_flags (obfd, "load", flags);
486 warning (_("Couldn't make gcore segment: %s"),
487 bfd_errmsg (bfd_get_error ()));
493 fprintf_filtered (gdb_stdout, "Save segment, %s bytes at %s\n",
494 plongest (size), paddress (target_gdbarch (), vaddr));
497 bfd_set_section_size (obfd, osec, size);
498 bfd_set_section_vma (obfd, osec, vaddr);
499 bfd_section_lma (obfd, osec) = 0; /* ??? bfd_set_section_lma? */
504 objfile_find_memory_regions (struct target_ops *self,
505 find_memory_region_ftype func, void *obfd)
507 /* Use objfile data to create memory sections. */
508 struct objfile *objfile;
509 struct obj_section *objsec;
510 bfd_vma temp_bottom, temp_top;
512 /* Call callback function for each objfile section. */
513 ALL_OBJSECTIONS (objfile, objsec)
515 bfd *ibfd = objfile->obfd;
516 asection *isec = objsec->the_bfd_section;
517 flagword flags = bfd_get_section_flags (ibfd, isec);
519 /* Separate debug info files are irrelevant for gcore. */
520 if (objfile->separate_debug_objfile_backlink != NULL)
523 if ((flags & SEC_ALLOC) || (flags & SEC_LOAD))
525 int size = bfd_section_size (ibfd, isec);
528 ret = (*func) (obj_section_addr (objsec), size,
529 1, /* All sections will be readable. */
530 (flags & SEC_READONLY) == 0, /* Writable. */
531 (flags & SEC_CODE) != 0, /* Executable. */
532 1, /* MODIFIED is unknown, pass it as true. */
539 /* Make a stack segment. */
540 if (derive_stack_segment (&temp_bottom, &temp_top))
541 (*func) (temp_bottom, temp_top - temp_bottom,
542 1, /* Stack section will be readable. */
543 1, /* Stack section will be writable. */
544 0, /* Stack section will not be executable. */
545 1, /* Stack section will be modified. */
548 /* Make a heap segment. */
549 if (derive_heap_segment (exec_bfd, &temp_bottom, &temp_top))
550 (*func) (temp_bottom, temp_top - temp_bottom,
551 1, /* Heap section will be readable. */
552 1, /* Heap section will be writable. */
553 0, /* Heap section will not be executable. */
554 1, /* Heap section will be modified. */
561 gcore_copy_callback (bfd *obfd, asection *osec, void *ignored)
563 bfd_size_type size, total_size = bfd_section_size (obfd, osec);
565 struct cleanup *old_chain = NULL;
568 /* Read-only sections are marked; we don't have to copy their contents. */
569 if ((bfd_get_section_flags (obfd, osec) & SEC_LOAD) == 0)
572 /* Only interested in "load" sections. */
573 if (!startswith (bfd_section_name (obfd, osec), "load"))
576 size = std::min (total_size, (bfd_size_type) MAX_COPY_BYTES);
577 memhunk = (gdb_byte *) xmalloc (size);
578 old_chain = make_cleanup (xfree, memhunk);
580 while (total_size > 0)
582 if (size > total_size)
585 if (target_read_memory (bfd_section_vma (obfd, osec) + offset,
588 warning (_("Memory read failed for corefile "
589 "section, %s bytes at %s."),
591 paddress (target_gdbarch (), bfd_section_vma (obfd, osec)));
594 if (!bfd_set_section_contents (obfd, osec, memhunk, offset, size))
596 warning (_("Failed to write corefile contents (%s)."),
597 bfd_errmsg (bfd_get_error ()));
605 do_cleanups (old_chain); /* Frees MEMHUNK. */
609 gcore_memory_sections (bfd *obfd)
611 /* Try gdbarch method first, then fall back to target method. */
612 if (!gdbarch_find_memory_regions_p (target_gdbarch ())
613 || gdbarch_find_memory_regions (target_gdbarch (),
614 gcore_create_callback, obfd) != 0)
616 if (target_find_memory_regions (gcore_create_callback, obfd) != 0)
617 return 0; /* FIXME: error return/msg? */
620 /* Record phdrs for section-to-segment mapping. */
621 bfd_map_over_sections (obfd, make_output_phdrs, NULL);
623 /* Copy memory region contents. */
624 bfd_map_over_sections (obfd, gcore_copy_callback, NULL);
629 /* Provide a prototype to silence -Wmissing-prototypes. */
630 extern initialize_file_ftype _initialize_gcore;
633 _initialize_gcore (void)
635 add_com ("generate-core-file", class_files, gcore_command, _("\
636 Save a core file with the current state of the debugged process.\n\
637 Argument is optional filename. Default filename is 'core.<process_id>'."));
639 add_com_alias ("gcore", "generate-core-file", class_files, 1);