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
: all_objfiles (current_program_space
))
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
: all_objfiles (current_program_space
))
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);