1 /* Generate a core file for the inferior process.
3 Copyright (C) 2001-2019 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"
38 #include "common/gdb_unlinker.h"
39 #include "byte-vector.h"
41 /* The largest amount of memory to read from the target at once. We
42 must throttle it to limit the amount of memory used by GDB during
43 generate-core-file for programs with large resident data. */
44 #define MAX_COPY_BYTES (1024 * 1024)
46 static const char *default_gcore_target (void);
47 static enum bfd_architecture default_gcore_arch (void);
48 static unsigned long default_gcore_mach (void);
49 static int gcore_memory_sections (bfd *);
51 /* create_gcore_bfd -- helper for gcore_command (exported).
52 Open a new bfd core file for output, and return the handle. */
55 create_gcore_bfd (const char *filename)
57 gdb_bfd_ref_ptr obfd (gdb_bfd_openw (filename, default_gcore_target ()));
60 error (_("Failed to open '%s' for output."), filename);
61 bfd_set_format (obfd.get (), bfd_core);
62 bfd_set_arch_mach (obfd.get (), default_gcore_arch (), default_gcore_mach ());
66 /* write_gcore_file_1 -- do the actual work of write_gcore_file. */
69 write_gcore_file_1 (bfd *obfd)
71 gdb::unique_xmalloc_ptr<char> note_data;
73 asection *note_sec = NULL;
75 /* An external target method must build the notes section. */
76 /* FIXME: uweigand/2011-10-06: All architectures that support core file
77 generation should be converted to gdbarch_make_corefile_notes; at that
78 point, the target vector method can be removed. */
79 if (!gdbarch_make_corefile_notes_p (target_gdbarch ()))
80 note_data.reset (target_make_corefile_notes (obfd, ¬e_size));
82 note_data.reset (gdbarch_make_corefile_notes (target_gdbarch (), obfd,
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.get (), 0,
108 warning (_("writing note section (%s)"), bfd_errmsg (bfd_get_error ()));
111 /* write_gcore_file -- helper for gcore_command (exported).
112 Compose and write the corefile data to the core file. */
115 write_gcore_file (bfd *obfd)
117 struct gdb_exception except = exception_none;
119 target_prepare_to_generate_core ();
123 write_gcore_file_1 (obfd);
125 CATCH (e, RETURN_MASK_ALL)
131 target_done_generating_core ();
133 if (except.reason < 0)
134 throw_exception (except);
137 /* gcore_command -- implements the 'gcore' command.
138 Generate a core file from the inferior process. */
141 gcore_command (const char *args, int from_tty)
143 gdb::unique_xmalloc_ptr<char> corefilename;
145 /* No use generating a corefile without a target process. */
146 if (!target_has_execution)
150 corefilename.reset (tilde_expand (args));
153 /* Default corefile name is "core.PID". */
154 corefilename.reset (xstrprintf ("core.%d", inferior_ptid.pid ()));
158 fprintf_filtered (gdb_stdout,
159 "Opening corefile '%s' for output.\n",
160 corefilename.get ());
162 /* Open the output file. */
163 gdb_bfd_ref_ptr obfd (create_gcore_bfd (corefilename.get ()));
165 /* Arrange to unlink the file on failure. */
166 gdb::unlinker unlink_file (corefilename.get ());
168 /* Call worker function. */
169 write_gcore_file (obfd.get ());
174 fprintf_filtered (gdb_stdout, "Saved corefile %s\n", corefilename.get ());
178 default_gcore_mach (void)
180 #if 1 /* See if this even matters... */
184 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch ());
187 return bfdarch->mach;
188 if (exec_bfd == NULL)
189 error (_("Can't find default bfd machine type (need execfile)."));
191 return bfd_get_mach (exec_bfd);
195 static enum bfd_architecture
196 default_gcore_arch (void)
198 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch ());
201 return bfdarch->arch;
202 if (exec_bfd == NULL)
203 error (_("Can't find bfd architecture for corefile (need execfile)."));
205 return bfd_get_arch (exec_bfd);
209 default_gcore_target (void)
211 /* The gdbarch may define a target to use for core files. */
212 if (gdbarch_gcore_bfd_target_p (target_gdbarch ()))
213 return gdbarch_gcore_bfd_target (target_gdbarch ());
215 /* Otherwise, try to fall back to the exec_bfd target. This will probably
216 not work for non-ELF targets. */
217 if (exec_bfd == NULL)
220 return bfd_get_target (exec_bfd);
223 /* Derive a reasonable stack segment by unwinding the target stack,
224 and store its limits in *BOTTOM and *TOP. Return non-zero if
228 derive_stack_segment (bfd_vma *bottom, bfd_vma *top)
230 struct frame_info *fi, *tmp_fi;
235 /* Can't succeed without stack and registers. */
236 if (!target_has_stack || !target_has_registers)
239 /* Can't succeed without current frame. */
240 fi = get_current_frame ();
244 /* Save frame pointer of TOS frame. */
245 *top = get_frame_base (fi);
246 /* If current stack pointer is more "inner", use that instead. */
247 if (gdbarch_inner_than (get_frame_arch (fi), get_frame_sp (fi), *top))
248 *top = get_frame_sp (fi);
250 /* Find prev-most frame. */
251 while ((tmp_fi = get_prev_frame (fi)) != NULL)
254 /* Save frame pointer of prev-most frame. */
255 *bottom = get_frame_base (fi);
257 /* Now canonicalize their order, so that BOTTOM is a lower address
258 (as opposed to a lower stack frame). */
271 /* call_target_sbrk --
272 helper function for derive_heap_segment. */
275 call_target_sbrk (int sbrk_arg)
277 struct objfile *sbrk_objf;
278 struct gdbarch *gdbarch;
280 struct value *target_sbrk_arg;
281 struct value *sbrk_fn, *ret;
284 if (lookup_minimal_symbol ("sbrk", NULL, NULL).minsym != NULL)
286 sbrk_fn = find_function_in_inferior ("sbrk", &sbrk_objf);
290 else if (lookup_minimal_symbol ("_sbrk", NULL, NULL).minsym != NULL)
292 sbrk_fn = find_function_in_inferior ("_sbrk", &sbrk_objf);
299 gdbarch = get_objfile_arch (sbrk_objf);
300 target_sbrk_arg = value_from_longest (builtin_type (gdbarch)->builtin_int,
302 gdb_assert (target_sbrk_arg);
303 ret = call_function_by_hand (sbrk_fn, NULL, target_sbrk_arg);
307 tmp = value_as_long (ret);
308 if ((LONGEST) tmp <= 0 || (LONGEST) tmp == 0xffffffff)
315 /* Derive a reasonable heap segment for ABFD by looking at sbrk and
316 the static data sections. Store its limits in *BOTTOM and *TOP.
317 Return non-zero if successful. */
320 derive_heap_segment (bfd *abfd, bfd_vma *bottom, bfd_vma *top)
322 bfd_vma top_of_data_memory = 0;
323 bfd_vma top_of_heap = 0;
324 bfd_size_type sec_size;
331 /* This function depends on being able to call a function in the
333 if (!target_has_execution)
336 /* The following code assumes that the link map is arranged as
337 follows (low to high addresses):
339 ---------------------------------
341 ---------------------------------
342 | data sections (including bss) |
343 ---------------------------------
345 --------------------------------- */
347 for (sec = abfd->sections; sec; sec = sec->next)
349 if (bfd_get_section_flags (abfd, sec) & SEC_DATA
350 || strcmp (".bss", bfd_section_name (abfd, sec)) == 0)
352 sec_vaddr = bfd_get_section_vma (abfd, sec);
353 sec_size = bfd_get_section_size (sec);
354 if (sec_vaddr + sec_size > top_of_data_memory)
355 top_of_data_memory = sec_vaddr + sec_size;
359 top_of_heap = call_target_sbrk (0);
360 if (top_of_heap == (bfd_vma) 0)
363 /* Return results. */
364 if (top_of_heap > top_of_data_memory)
366 *bottom = top_of_data_memory;
371 /* No additional heap space needs to be saved. */
376 make_output_phdrs (bfd *obfd, asection *osec, void *ignored)
381 /* FIXME: these constants may only be applicable for ELF. */
382 if (startswith (bfd_section_name (obfd, osec), "load"))
384 else if (startswith (bfd_section_name (obfd, osec), "note"))
389 p_flags |= PF_R; /* Segment is readable. */
390 if (!(bfd_get_section_flags (obfd, osec) & SEC_READONLY))
391 p_flags |= PF_W; /* Segment is writable. */
392 if (bfd_get_section_flags (obfd, osec) & SEC_CODE)
393 p_flags |= PF_X; /* Segment is executable. */
395 bfd_record_phdr (obfd, p_type, 1, p_flags, 0, 0, 0, 0, 1, &osec);
398 /* find_memory_region_ftype implementation. DATA is 'bfd *' for the core file
402 gcore_create_callback (CORE_ADDR vaddr, unsigned long size, int read,
403 int write, int exec, int modified, void *data)
405 bfd *obfd = (bfd *) data;
407 flagword flags = SEC_ALLOC | SEC_HAS_CONTENTS | SEC_LOAD;
409 /* If the memory segment has no permissions set, ignore it, otherwise
410 when we later try to access it for read/write, we'll get an error
411 or jam the kernel. */
412 if (read == 0 && write == 0 && exec == 0 && modified == 0)
416 fprintf_filtered (gdb_stdout, "Ignore segment, %s bytes at %s\n",
417 plongest (size), paddress (target_gdbarch (), vaddr));
423 if (write == 0 && modified == 0 && !solib_keep_data_in_core (vaddr, size))
425 /* See if this region of memory lies inside a known file on disk.
426 If so, we can avoid copying its contents by clearing SEC_LOAD. */
427 struct obj_section *objsec;
429 for (objfile *objfile : current_program_space->objfiles ())
430 ALL_OBJFILE_OSECTIONS (objfile, objsec)
432 bfd *abfd = objfile->obfd;
433 asection *asec = objsec->the_bfd_section;
434 bfd_vma align = (bfd_vma) 1 << bfd_get_section_alignment (abfd,
436 bfd_vma start = obj_section_addr (objsec) & -align;
437 bfd_vma end = (obj_section_endaddr (objsec) + align - 1) & -align;
439 /* Match if either the entire memory region lies inside the
440 section (i.e. a mapping covering some pages of a large
441 segment) or the entire section lies inside the memory region
442 (i.e. a mapping covering multiple small sections).
444 This BFD was synthesized from reading target memory,
445 we don't want to omit that. */
446 if (objfile->separate_debug_objfile_backlink == NULL
447 && ((vaddr >= start && vaddr + size <= end)
448 || (start >= vaddr && end <= vaddr + size))
449 && !(bfd_get_file_flags (abfd) & BFD_IN_MEMORY))
451 flags &= ~(SEC_LOAD | SEC_HAS_CONTENTS);
452 goto keep; /* Break out of two nested for loops. */
460 flags |= SEC_READONLY;
467 osec = bfd_make_section_anyway_with_flags (obfd, "load", flags);
470 warning (_("Couldn't make gcore segment: %s"),
471 bfd_errmsg (bfd_get_error ()));
477 fprintf_filtered (gdb_stdout, "Save segment, %s bytes at %s\n",
478 plongest (size), paddress (target_gdbarch (), vaddr));
481 bfd_set_section_size (obfd, osec, size);
482 bfd_set_section_vma (obfd, osec, vaddr);
483 bfd_section_lma (obfd, osec) = 0; /* ??? bfd_set_section_lma? */
488 objfile_find_memory_regions (struct target_ops *self,
489 find_memory_region_ftype func, void *obfd)
491 /* Use objfile data to create memory sections. */
492 struct obj_section *objsec;
493 bfd_vma temp_bottom, temp_top;
495 /* Call callback function for each objfile section. */
496 for (objfile *objfile : current_program_space->objfiles ())
497 ALL_OBJFILE_OSECTIONS (objfile, objsec)
499 bfd *ibfd = objfile->obfd;
500 asection *isec = objsec->the_bfd_section;
501 flagword flags = bfd_get_section_flags (ibfd, isec);
503 /* Separate debug info files are irrelevant for gcore. */
504 if (objfile->separate_debug_objfile_backlink != NULL)
507 if ((flags & SEC_ALLOC) || (flags & SEC_LOAD))
509 int size = bfd_section_size (ibfd, isec);
512 ret = (*func) (obj_section_addr (objsec), size,
513 1, /* All sections will be readable. */
514 (flags & SEC_READONLY) == 0, /* Writable. */
515 (flags & SEC_CODE) != 0, /* Executable. */
516 1, /* MODIFIED is unknown, pass it as true. */
523 /* Make a stack segment. */
524 if (derive_stack_segment (&temp_bottom, &temp_top))
525 (*func) (temp_bottom, temp_top - temp_bottom,
526 1, /* Stack section will be readable. */
527 1, /* Stack section will be writable. */
528 0, /* Stack section will not be executable. */
529 1, /* Stack section will be modified. */
532 /* Make a heap segment. */
533 if (derive_heap_segment (exec_bfd, &temp_bottom, &temp_top))
534 (*func) (temp_bottom, temp_top - temp_bottom,
535 1, /* Heap section will be readable. */
536 1, /* Heap section will be writable. */
537 0, /* Heap section will not be executable. */
538 1, /* Heap section will be modified. */
545 gcore_copy_callback (bfd *obfd, asection *osec, void *ignored)
547 bfd_size_type size, total_size = bfd_section_size (obfd, osec);
550 /* Read-only sections are marked; we don't have to copy their contents. */
551 if ((bfd_get_section_flags (obfd, osec) & SEC_LOAD) == 0)
554 /* Only interested in "load" sections. */
555 if (!startswith (bfd_section_name (obfd, osec), "load"))
558 size = std::min (total_size, (bfd_size_type) MAX_COPY_BYTES);
559 gdb::byte_vector memhunk (size);
561 while (total_size > 0)
563 if (size > total_size)
566 if (target_read_memory (bfd_section_vma (obfd, osec) + offset,
567 memhunk.data (), size) != 0)
569 warning (_("Memory read failed for corefile "
570 "section, %s bytes at %s."),
572 paddress (target_gdbarch (), bfd_section_vma (obfd, osec)));
575 if (!bfd_set_section_contents (obfd, osec, memhunk.data (),
578 warning (_("Failed to write corefile contents (%s)."),
579 bfd_errmsg (bfd_get_error ()));
589 gcore_memory_sections (bfd *obfd)
591 /* Try gdbarch method first, then fall back to target method. */
592 if (!gdbarch_find_memory_regions_p (target_gdbarch ())
593 || gdbarch_find_memory_regions (target_gdbarch (),
594 gcore_create_callback, obfd) != 0)
596 if (target_find_memory_regions (gcore_create_callback, obfd) != 0)
597 return 0; /* FIXME: error return/msg? */
600 /* Record phdrs for section-to-segment mapping. */
601 bfd_map_over_sections (obfd, make_output_phdrs, NULL);
603 /* Copy memory region contents. */
604 bfd_map_over_sections (obfd, gcore_copy_callback, NULL);
610 _initialize_gcore (void)
612 add_com ("generate-core-file", class_files, gcore_command, _("\
613 Save a core file with the current state of the debugged process.\n\
614 Usage: generate-core-file [FILENAME]\n\
615 Argument is optional filename. Default filename is 'core.PROCESS_ID'."));
617 add_com_alias ("gcore", "generate-core-file", class_files, 1);