1 /* Generate a core file for the inferior process.
3 Copyright (C) 2001-2017 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 struct cleanup *cleanup;
72 void *note_data = NULL;
74 asection *note_sec = NULL;
76 /* An external target method must build the notes section. */
77 /* FIXME: uweigand/2011-10-06: All architectures that support core file
78 generation should be converted to gdbarch_make_corefile_notes; at that
79 point, the target vector method can be removed. */
80 if (!gdbarch_make_corefile_notes_p (target_gdbarch ()))
81 note_data = target_make_corefile_notes (obfd, ¬e_size);
83 note_data = gdbarch_make_corefile_notes (target_gdbarch (), obfd, ¬e_size);
85 cleanup = make_cleanup (xfree, note_data);
87 if (note_data == NULL || note_size == 0)
88 error (_("Target does not support core file generation."));
90 /* Create the note section. */
91 note_sec = bfd_make_section_anyway_with_flags (obfd, "note0",
96 error (_("Failed to create 'note' section for corefile: %s"),
97 bfd_errmsg (bfd_get_error ()));
99 bfd_set_section_vma (obfd, note_sec, 0);
100 bfd_set_section_alignment (obfd, note_sec, 0);
101 bfd_set_section_size (obfd, note_sec, note_size);
103 /* Now create the memory/load sections. */
104 if (gcore_memory_sections (obfd) == 0)
105 error (_("gcore: failed to get corefile memory sections from target."));
107 /* Write out the contents of the note section. */
108 if (!bfd_set_section_contents (obfd, note_sec, note_data, 0, note_size))
109 warning (_("writing note section (%s)"), bfd_errmsg (bfd_get_error ()));
111 do_cleanups (cleanup);
114 /* write_gcore_file -- helper for gcore_command (exported).
115 Compose and write the corefile data to the core file. */
118 write_gcore_file (bfd *obfd)
120 struct gdb_exception except = exception_none;
122 target_prepare_to_generate_core ();
126 write_gcore_file_1 (obfd);
128 CATCH (e, RETURN_MASK_ALL)
134 target_done_generating_core ();
136 if (except.reason < 0)
137 throw_exception (except);
140 /* gcore_command -- implements the 'gcore' command.
141 Generate a core file from the inferior process. */
144 gcore_command (char *args, int from_tty)
146 gdb::unique_xmalloc_ptr<char> corefilename;
148 /* No use generating a corefile without a target process. */
149 if (!target_has_execution)
153 corefilename.reset (tilde_expand (args));
156 /* Default corefile name is "core.PID". */
157 corefilename.reset (xstrprintf ("core.%d", ptid_get_pid (inferior_ptid)));
161 fprintf_filtered (gdb_stdout,
162 "Opening corefile '%s' for output.\n",
163 corefilename.get ());
165 /* Open the output file. */
166 gdb_bfd_ref_ptr obfd (create_gcore_bfd (corefilename.get ()));
168 /* Arrange to unlink the file on failure. */
169 gdb::unlinker unlink_file (corefilename.get ());
171 /* Call worker function. */
172 write_gcore_file (obfd.get ());
177 fprintf_filtered (gdb_stdout, "Saved corefile %s\n", corefilename.get ());
181 default_gcore_mach (void)
183 #if 1 /* See if this even matters... */
187 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch ());
190 return bfdarch->mach;
191 if (exec_bfd == NULL)
192 error (_("Can't find default bfd machine type (need execfile)."));
194 return bfd_get_mach (exec_bfd);
198 static enum bfd_architecture
199 default_gcore_arch (void)
201 const struct bfd_arch_info *bfdarch = gdbarch_bfd_arch_info (target_gdbarch ());
204 return bfdarch->arch;
205 if (exec_bfd == NULL)
206 error (_("Can't find bfd architecture for corefile (need execfile)."));
208 return bfd_get_arch (exec_bfd);
212 default_gcore_target (void)
214 /* The gdbarch may define a target to use for core files. */
215 if (gdbarch_gcore_bfd_target_p (target_gdbarch ()))
216 return gdbarch_gcore_bfd_target (target_gdbarch ());
218 /* Otherwise, try to fall back to the exec_bfd target. This will probably
219 not work for non-ELF targets. */
220 if (exec_bfd == NULL)
223 return bfd_get_target (exec_bfd);
226 /* Derive a reasonable stack segment by unwinding the target stack,
227 and store its limits in *BOTTOM and *TOP. Return non-zero if
231 derive_stack_segment (bfd_vma *bottom, bfd_vma *top)
233 struct frame_info *fi, *tmp_fi;
238 /* Can't succeed without stack and registers. */
239 if (!target_has_stack || !target_has_registers)
242 /* Can't succeed without current frame. */
243 fi = get_current_frame ();
247 /* Save frame pointer of TOS frame. */
248 *top = get_frame_base (fi);
249 /* If current stack pointer is more "inner", use that instead. */
250 if (gdbarch_inner_than (get_frame_arch (fi), get_frame_sp (fi), *top))
251 *top = get_frame_sp (fi);
253 /* Find prev-most frame. */
254 while ((tmp_fi = get_prev_frame (fi)) != NULL)
257 /* Save frame pointer of prev-most frame. */
258 *bottom = get_frame_base (fi);
260 /* Now canonicalize their order, so that BOTTOM is a lower address
261 (as opposed to a lower stack frame). */
274 /* call_target_sbrk --
275 helper function for derive_heap_segment. */
278 call_target_sbrk (int sbrk_arg)
280 struct objfile *sbrk_objf;
281 struct gdbarch *gdbarch;
283 struct value *target_sbrk_arg;
284 struct value *sbrk_fn, *ret;
287 if (lookup_minimal_symbol ("sbrk", NULL, NULL).minsym != NULL)
289 sbrk_fn = find_function_in_inferior ("sbrk", &sbrk_objf);
293 else if (lookup_minimal_symbol ("_sbrk", NULL, NULL).minsym != NULL)
295 sbrk_fn = find_function_in_inferior ("_sbrk", &sbrk_objf);
302 gdbarch = get_objfile_arch (sbrk_objf);
303 target_sbrk_arg = value_from_longest (builtin_type (gdbarch)->builtin_int,
305 gdb_assert (target_sbrk_arg);
306 ret = call_function_by_hand (sbrk_fn, NULL, 1, &target_sbrk_arg);
310 tmp = value_as_long (ret);
311 if ((LONGEST) tmp <= 0 || (LONGEST) tmp == 0xffffffff)
318 /* Derive a reasonable heap segment for ABFD by looking at sbrk and
319 the static data sections. Store its limits in *BOTTOM and *TOP.
320 Return non-zero if successful. */
323 derive_heap_segment (bfd *abfd, bfd_vma *bottom, bfd_vma *top)
325 bfd_vma top_of_data_memory = 0;
326 bfd_vma top_of_heap = 0;
327 bfd_size_type sec_size;
334 /* This function depends on being able to call a function in the
336 if (!target_has_execution)
339 /* The following code assumes that the link map is arranged as
340 follows (low to high addresses):
342 ---------------------------------
344 ---------------------------------
345 | data sections (including bss) |
346 ---------------------------------
348 --------------------------------- */
350 for (sec = abfd->sections; sec; sec = sec->next)
352 if (bfd_get_section_flags (abfd, sec) & SEC_DATA
353 || strcmp (".bss", bfd_section_name (abfd, sec)) == 0)
355 sec_vaddr = bfd_get_section_vma (abfd, sec);
356 sec_size = bfd_get_section_size (sec);
357 if (sec_vaddr + sec_size > top_of_data_memory)
358 top_of_data_memory = sec_vaddr + sec_size;
362 top_of_heap = call_target_sbrk (0);
363 if (top_of_heap == (bfd_vma) 0)
366 /* Return results. */
367 if (top_of_heap > top_of_data_memory)
369 *bottom = top_of_data_memory;
374 /* No additional heap space needs to be saved. */
379 make_output_phdrs (bfd *obfd, asection *osec, void *ignored)
384 /* FIXME: these constants may only be applicable for ELF. */
385 if (startswith (bfd_section_name (obfd, osec), "load"))
387 else if (startswith (bfd_section_name (obfd, osec), "note"))
392 p_flags |= PF_R; /* Segment is readable. */
393 if (!(bfd_get_section_flags (obfd, osec) & SEC_READONLY))
394 p_flags |= PF_W; /* Segment is writable. */
395 if (bfd_get_section_flags (obfd, osec) & SEC_CODE)
396 p_flags |= PF_X; /* Segment is executable. */
398 bfd_record_phdr (obfd, p_type, 1, p_flags, 0, 0, 0, 0, 1, &osec);
401 /* find_memory_region_ftype implementation. DATA is 'bfd *' for the core file
405 gcore_create_callback (CORE_ADDR vaddr, unsigned long size, int read,
406 int write, int exec, int modified, void *data)
408 bfd *obfd = (bfd *) data;
410 flagword flags = SEC_ALLOC | SEC_HAS_CONTENTS | SEC_LOAD;
412 /* If the memory segment has no permissions set, ignore it, otherwise
413 when we later try to access it for read/write, we'll get an error
414 or jam the kernel. */
415 if (read == 0 && write == 0 && exec == 0 && modified == 0)
419 fprintf_filtered (gdb_stdout, "Ignore segment, %s bytes at %s\n",
420 plongest (size), paddress (target_gdbarch (), vaddr));
426 if (write == 0 && modified == 0 && !solib_keep_data_in_core (vaddr, size))
428 /* See if this region of memory lies inside a known file on disk.
429 If so, we can avoid copying its contents by clearing SEC_LOAD. */
430 struct objfile *objfile;
431 struct obj_section *objsec;
433 ALL_OBJSECTIONS (objfile, objsec)
435 bfd *abfd = objfile->obfd;
436 asection *asec = objsec->the_bfd_section;
437 bfd_vma align = (bfd_vma) 1 << bfd_get_section_alignment (abfd,
439 bfd_vma start = obj_section_addr (objsec) & -align;
440 bfd_vma end = (obj_section_endaddr (objsec) + align - 1) & -align;
442 /* Match if either the entire memory region lies inside the
443 section (i.e. a mapping covering some pages of a large
444 segment) or the entire section lies inside the memory region
445 (i.e. a mapping covering multiple small sections).
447 This BFD was synthesized from reading target memory,
448 we don't want to omit that. */
449 if (objfile->separate_debug_objfile_backlink == NULL
450 && ((vaddr >= start && vaddr + size <= end)
451 || (start >= vaddr && end <= vaddr + size))
452 && !(bfd_get_file_flags (abfd) & BFD_IN_MEMORY))
454 flags &= ~(SEC_LOAD | SEC_HAS_CONTENTS);
455 goto keep; /* Break out of two nested for loops. */
463 flags |= SEC_READONLY;
470 osec = bfd_make_section_anyway_with_flags (obfd, "load", flags);
473 warning (_("Couldn't make gcore segment: %s"),
474 bfd_errmsg (bfd_get_error ()));
480 fprintf_filtered (gdb_stdout, "Save segment, %s bytes at %s\n",
481 plongest (size), paddress (target_gdbarch (), vaddr));
484 bfd_set_section_size (obfd, osec, size);
485 bfd_set_section_vma (obfd, osec, vaddr);
486 bfd_section_lma (obfd, osec) = 0; /* ??? bfd_set_section_lma? */
491 objfile_find_memory_regions (struct target_ops *self,
492 find_memory_region_ftype func, void *obfd)
494 /* Use objfile data to create memory sections. */
495 struct objfile *objfile;
496 struct obj_section *objsec;
497 bfd_vma temp_bottom, temp_top;
499 /* Call callback function for each objfile section. */
500 ALL_OBJSECTIONS (objfile, objsec)
502 bfd *ibfd = objfile->obfd;
503 asection *isec = objsec->the_bfd_section;
504 flagword flags = bfd_get_section_flags (ibfd, isec);
506 /* Separate debug info files are irrelevant for gcore. */
507 if (objfile->separate_debug_objfile_backlink != NULL)
510 if ((flags & SEC_ALLOC) || (flags & SEC_LOAD))
512 int size = bfd_section_size (ibfd, isec);
515 ret = (*func) (obj_section_addr (objsec), size,
516 1, /* All sections will be readable. */
517 (flags & SEC_READONLY) == 0, /* Writable. */
518 (flags & SEC_CODE) != 0, /* Executable. */
519 1, /* MODIFIED is unknown, pass it as true. */
526 /* Make a stack segment. */
527 if (derive_stack_segment (&temp_bottom, &temp_top))
528 (*func) (temp_bottom, temp_top - temp_bottom,
529 1, /* Stack section will be readable. */
530 1, /* Stack section will be writable. */
531 0, /* Stack section will not be executable. */
532 1, /* Stack section will be modified. */
535 /* Make a heap segment. */
536 if (derive_heap_segment (exec_bfd, &temp_bottom, &temp_top))
537 (*func) (temp_bottom, temp_top - temp_bottom,
538 1, /* Heap section will be readable. */
539 1, /* Heap section will be writable. */
540 0, /* Heap section will not be executable. */
541 1, /* Heap section will be modified. */
548 gcore_copy_callback (bfd *obfd, asection *osec, void *ignored)
550 bfd_size_type size, total_size = bfd_section_size (obfd, osec);
553 /* Read-only sections are marked; we don't have to copy their contents. */
554 if ((bfd_get_section_flags (obfd, osec) & SEC_LOAD) == 0)
557 /* Only interested in "load" sections. */
558 if (!startswith (bfd_section_name (obfd, osec), "load"))
561 size = std::min (total_size, (bfd_size_type) MAX_COPY_BYTES);
562 gdb::byte_vector memhunk (size);
564 while (total_size > 0)
566 if (size > total_size)
569 if (target_read_memory (bfd_section_vma (obfd, osec) + offset,
570 memhunk.data (), size) != 0)
572 warning (_("Memory read failed for corefile "
573 "section, %s bytes at %s."),
575 paddress (target_gdbarch (), bfd_section_vma (obfd, osec)));
578 if (!bfd_set_section_contents (obfd, osec, memhunk.data (),
581 warning (_("Failed to write corefile contents (%s)."),
582 bfd_errmsg (bfd_get_error ()));
592 gcore_memory_sections (bfd *obfd)
594 /* Try gdbarch method first, then fall back to target method. */
595 if (!gdbarch_find_memory_regions_p (target_gdbarch ())
596 || gdbarch_find_memory_regions (target_gdbarch (),
597 gcore_create_callback, obfd) != 0)
599 if (target_find_memory_regions (gcore_create_callback, obfd) != 0)
600 return 0; /* FIXME: error return/msg? */
603 /* Record phdrs for section-to-segment mapping. */
604 bfd_map_over_sections (obfd, make_output_phdrs, NULL);
606 /* Copy memory region contents. */
607 bfd_map_over_sections (obfd, gcore_copy_callback, NULL);
613 _initialize_gcore (void)
615 add_com ("generate-core-file", class_files, gcore_command, _("\
616 Save a core file with the current state of the debugged process.\n\
617 Argument is optional filename. Default filename is 'core.<process_id>'."));
619 add_com_alias ("gcore", "generate-core-file", class_files, 1);