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"
40 /* The largest amount of memory to read from the target at once. We
41 must throttle it to limit the amount of memory used by GDB during
42 generate-core-file for programs with large resident data. */
43 #define MAX_COPY_BYTES (1024 * 1024)
45 static const char *default_gcore_target (void);
46 static enum bfd_architecture
default_gcore_arch (void);
47 static unsigned long default_gcore_mach (void);
48 static int gcore_memory_sections (bfd
*);
50 /* create_gcore_bfd -- helper for gcore_command (exported).
51 Open a new bfd core file for output, and return the handle. */
54 create_gcore_bfd (const char *filename
)
56 gdb_bfd_ref_ptr
obfd (gdb_bfd_openw (filename
, default_gcore_target ()));
59 error (_("Failed to open '%s' for output."), filename
);
60 bfd_set_format (obfd
.get (), bfd_core
);
61 bfd_set_arch_mach (obfd
.get (), default_gcore_arch (), default_gcore_mach ());
65 /* write_gcore_file_1 -- do the actual work of write_gcore_file. */
68 write_gcore_file_1 (bfd
*obfd
)
70 struct cleanup
*cleanup
;
71 void *note_data
= NULL
;
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
= target_make_corefile_notes (obfd
, ¬e_size
);
82 note_data
= gdbarch_make_corefile_notes (target_gdbarch (), obfd
, ¬e_size
);
84 cleanup
= make_cleanup (xfree
, note_data
);
86 if (note_data
== NULL
|| note_size
== 0)
87 error (_("Target does not support core file generation."));
89 /* Create the note section. */
90 note_sec
= bfd_make_section_anyway_with_flags (obfd
, "note0",
95 error (_("Failed to create 'note' section for corefile: %s"),
96 bfd_errmsg (bfd_get_error ()));
98 bfd_set_section_vma (obfd
, note_sec
, 0);
99 bfd_set_section_alignment (obfd
, note_sec
, 0);
100 bfd_set_section_size (obfd
, note_sec
, note_size
);
102 /* Now create the memory/load sections. */
103 if (gcore_memory_sections (obfd
) == 0)
104 error (_("gcore: failed to get corefile memory sections from target."));
106 /* Write out the contents of the note section. */
107 if (!bfd_set_section_contents (obfd
, note_sec
, note_data
, 0, note_size
))
108 warning (_("writing note section (%s)"), bfd_errmsg (bfd_get_error ()));
110 do_cleanups (cleanup
);
113 /* write_gcore_file -- helper for gcore_command (exported).
114 Compose and write the corefile data to the core file. */
117 write_gcore_file (bfd
*obfd
)
119 struct gdb_exception except
= exception_none
;
121 target_prepare_to_generate_core ();
125 write_gcore_file_1 (obfd
);
127 CATCH (e
, RETURN_MASK_ALL
)
133 target_done_generating_core ();
135 if (except
.reason
< 0)
136 throw_exception (except
);
139 /* gcore_command -- implements the 'gcore' command.
140 Generate a core file from the inferior process. */
143 gcore_command (char *args
, int from_tty
)
145 gdb::unique_xmalloc_ptr
<char> corefilename
;
147 /* No use generating a corefile without a target process. */
148 if (!target_has_execution
)
152 corefilename
.reset (tilde_expand (args
));
155 /* Default corefile name is "core.PID". */
156 corefilename
.reset (xstrprintf ("core.%d", ptid_get_pid (inferior_ptid
)));
160 fprintf_filtered (gdb_stdout
,
161 "Opening corefile '%s' for output.\n",
162 corefilename
.get ());
164 /* Open the output file. */
165 gdb_bfd_ref_ptr
obfd (create_gcore_bfd (corefilename
.get ()));
167 /* Arrange to unlink the file on failure. */
168 gdb::unlinker
unlink_file (corefilename
.get ());
170 /* Call worker function. */
171 write_gcore_file (obfd
.get ());
176 fprintf_filtered (gdb_stdout
, "Saved corefile %s\n", corefilename
.get ());
180 default_gcore_mach (void)
182 #if 1 /* See if this even matters... */
186 const struct bfd_arch_info
*bfdarch
= gdbarch_bfd_arch_info (target_gdbarch ());
189 return bfdarch
->mach
;
190 if (exec_bfd
== NULL
)
191 error (_("Can't find default bfd machine type (need execfile)."));
193 return bfd_get_mach (exec_bfd
);
197 static enum bfd_architecture
198 default_gcore_arch (void)
200 const struct bfd_arch_info
*bfdarch
= gdbarch_bfd_arch_info (target_gdbarch ());
203 return bfdarch
->arch
;
204 if (exec_bfd
== NULL
)
205 error (_("Can't find bfd architecture for corefile (need execfile)."));
207 return bfd_get_arch (exec_bfd
);
211 default_gcore_target (void)
213 /* The gdbarch may define a target to use for core files. */
214 if (gdbarch_gcore_bfd_target_p (target_gdbarch ()))
215 return gdbarch_gcore_bfd_target (target_gdbarch ());
217 /* Otherwise, try to fall back to the exec_bfd target. This will probably
218 not work for non-ELF targets. */
219 if (exec_bfd
== NULL
)
222 return bfd_get_target (exec_bfd
);
225 /* Derive a reasonable stack segment by unwinding the target stack,
226 and store its limits in *BOTTOM and *TOP. Return non-zero if
230 derive_stack_segment (bfd_vma
*bottom
, bfd_vma
*top
)
232 struct frame_info
*fi
, *tmp_fi
;
237 /* Can't succeed without stack and registers. */
238 if (!target_has_stack
|| !target_has_registers
)
241 /* Can't succeed without current frame. */
242 fi
= get_current_frame ();
246 /* Save frame pointer of TOS frame. */
247 *top
= get_frame_base (fi
);
248 /* If current stack pointer is more "inner", use that instead. */
249 if (gdbarch_inner_than (get_frame_arch (fi
), get_frame_sp (fi
), *top
))
250 *top
= get_frame_sp (fi
);
252 /* Find prev-most frame. */
253 while ((tmp_fi
= get_prev_frame (fi
)) != NULL
)
256 /* Save frame pointer of prev-most frame. */
257 *bottom
= get_frame_base (fi
);
259 /* Now canonicalize their order, so that BOTTOM is a lower address
260 (as opposed to a lower stack frame). */
273 /* call_target_sbrk --
274 helper function for derive_heap_segment. */
277 call_target_sbrk (int sbrk_arg
)
279 struct objfile
*sbrk_objf
;
280 struct gdbarch
*gdbarch
;
282 struct value
*target_sbrk_arg
;
283 struct value
*sbrk_fn
, *ret
;
286 if (lookup_minimal_symbol ("sbrk", NULL
, NULL
).minsym
!= NULL
)
288 sbrk_fn
= find_function_in_inferior ("sbrk", &sbrk_objf
);
292 else if (lookup_minimal_symbol ("_sbrk", NULL
, NULL
).minsym
!= NULL
)
294 sbrk_fn
= find_function_in_inferior ("_sbrk", &sbrk_objf
);
301 gdbarch
= get_objfile_arch (sbrk_objf
);
302 target_sbrk_arg
= value_from_longest (builtin_type (gdbarch
)->builtin_int
,
304 gdb_assert (target_sbrk_arg
);
305 ret
= call_function_by_hand (sbrk_fn
, 1, &target_sbrk_arg
);
309 tmp
= value_as_long (ret
);
310 if ((LONGEST
) tmp
<= 0 || (LONGEST
) tmp
== 0xffffffff)
317 /* Derive a reasonable heap segment for ABFD by looking at sbrk and
318 the static data sections. Store its limits in *BOTTOM and *TOP.
319 Return non-zero if successful. */
322 derive_heap_segment (bfd
*abfd
, bfd_vma
*bottom
, bfd_vma
*top
)
324 bfd_vma top_of_data_memory
= 0;
325 bfd_vma top_of_heap
= 0;
326 bfd_size_type sec_size
;
333 /* This function depends on being able to call a function in the
335 if (!target_has_execution
)
338 /* The following code assumes that the link map is arranged as
339 follows (low to high addresses):
341 ---------------------------------
343 ---------------------------------
344 | data sections (including bss) |
345 ---------------------------------
347 --------------------------------- */
349 for (sec
= abfd
->sections
; sec
; sec
= sec
->next
)
351 if (bfd_get_section_flags (abfd
, sec
) & SEC_DATA
352 || strcmp (".bss", bfd_section_name (abfd
, sec
)) == 0)
354 sec_vaddr
= bfd_get_section_vma (abfd
, sec
);
355 sec_size
= bfd_get_section_size (sec
);
356 if (sec_vaddr
+ sec_size
> top_of_data_memory
)
357 top_of_data_memory
= sec_vaddr
+ sec_size
;
361 top_of_heap
= call_target_sbrk (0);
362 if (top_of_heap
== (bfd_vma
) 0)
365 /* Return results. */
366 if (top_of_heap
> top_of_data_memory
)
368 *bottom
= top_of_data_memory
;
373 /* No additional heap space needs to be saved. */
378 make_output_phdrs (bfd
*obfd
, asection
*osec
, void *ignored
)
383 /* FIXME: these constants may only be applicable for ELF. */
384 if (startswith (bfd_section_name (obfd
, osec
), "load"))
386 else if (startswith (bfd_section_name (obfd
, osec
), "note"))
391 p_flags
|= PF_R
; /* Segment is readable. */
392 if (!(bfd_get_section_flags (obfd
, osec
) & SEC_READONLY
))
393 p_flags
|= PF_W
; /* Segment is writable. */
394 if (bfd_get_section_flags (obfd
, osec
) & SEC_CODE
)
395 p_flags
|= PF_X
; /* Segment is executable. */
397 bfd_record_phdr (obfd
, p_type
, 1, p_flags
, 0, 0, 0, 0, 1, &osec
);
400 /* find_memory_region_ftype implementation. DATA is 'bfd *' for the core file
404 gcore_create_callback (CORE_ADDR vaddr
, unsigned long size
, int read
,
405 int write
, int exec
, int modified
, void *data
)
407 bfd
*obfd
= (bfd
*) data
;
409 flagword flags
= SEC_ALLOC
| SEC_HAS_CONTENTS
| SEC_LOAD
;
411 /* If the memory segment has no permissions set, ignore it, otherwise
412 when we later try to access it for read/write, we'll get an error
413 or jam the kernel. */
414 if (read
== 0 && write
== 0 && exec
== 0 && modified
== 0)
418 fprintf_filtered (gdb_stdout
, "Ignore segment, %s bytes at %s\n",
419 plongest (size
), paddress (target_gdbarch (), vaddr
));
425 if (write
== 0 && modified
== 0 && !solib_keep_data_in_core (vaddr
, size
))
427 /* See if this region of memory lies inside a known file on disk.
428 If so, we can avoid copying its contents by clearing SEC_LOAD. */
429 struct objfile
*objfile
;
430 struct obj_section
*objsec
;
432 ALL_OBJSECTIONS (objfile
, objsec
)
434 bfd
*abfd
= objfile
->obfd
;
435 asection
*asec
= objsec
->the_bfd_section
;
436 bfd_vma align
= (bfd_vma
) 1 << bfd_get_section_alignment (abfd
,
438 bfd_vma start
= obj_section_addr (objsec
) & -align
;
439 bfd_vma end
= (obj_section_endaddr (objsec
) + align
- 1) & -align
;
441 /* Match if either the entire memory region lies inside the
442 section (i.e. a mapping covering some pages of a large
443 segment) or the entire section lies inside the memory region
444 (i.e. a mapping covering multiple small sections).
446 This BFD was synthesized from reading target memory,
447 we don't want to omit that. */
448 if (objfile
->separate_debug_objfile_backlink
== NULL
449 && ((vaddr
>= start
&& vaddr
+ size
<= end
)
450 || (start
>= vaddr
&& end
<= vaddr
+ size
))
451 && !(bfd_get_file_flags (abfd
) & BFD_IN_MEMORY
))
453 flags
&= ~(SEC_LOAD
| SEC_HAS_CONTENTS
);
454 goto keep
; /* Break out of two nested for loops. */
462 flags
|= SEC_READONLY
;
469 osec
= bfd_make_section_anyway_with_flags (obfd
, "load", flags
);
472 warning (_("Couldn't make gcore segment: %s"),
473 bfd_errmsg (bfd_get_error ()));
479 fprintf_filtered (gdb_stdout
, "Save segment, %s bytes at %s\n",
480 plongest (size
), paddress (target_gdbarch (), vaddr
));
483 bfd_set_section_size (obfd
, osec
, size
);
484 bfd_set_section_vma (obfd
, osec
, vaddr
);
485 bfd_section_lma (obfd
, osec
) = 0; /* ??? bfd_set_section_lma? */
490 objfile_find_memory_regions (struct target_ops
*self
,
491 find_memory_region_ftype func
, void *obfd
)
493 /* Use objfile data to create memory sections. */
494 struct objfile
*objfile
;
495 struct obj_section
*objsec
;
496 bfd_vma temp_bottom
, temp_top
;
498 /* Call callback function for each objfile section. */
499 ALL_OBJSECTIONS (objfile
, objsec
)
501 bfd
*ibfd
= objfile
->obfd
;
502 asection
*isec
= objsec
->the_bfd_section
;
503 flagword flags
= bfd_get_section_flags (ibfd
, isec
);
505 /* Separate debug info files are irrelevant for gcore. */
506 if (objfile
->separate_debug_objfile_backlink
!= NULL
)
509 if ((flags
& SEC_ALLOC
) || (flags
& SEC_LOAD
))
511 int size
= bfd_section_size (ibfd
, isec
);
514 ret
= (*func
) (obj_section_addr (objsec
), size
,
515 1, /* All sections will be readable. */
516 (flags
& SEC_READONLY
) == 0, /* Writable. */
517 (flags
& SEC_CODE
) != 0, /* Executable. */
518 1, /* MODIFIED is unknown, pass it as true. */
525 /* Make a stack segment. */
526 if (derive_stack_segment (&temp_bottom
, &temp_top
))
527 (*func
) (temp_bottom
, temp_top
- temp_bottom
,
528 1, /* Stack section will be readable. */
529 1, /* Stack section will be writable. */
530 0, /* Stack section will not be executable. */
531 1, /* Stack section will be modified. */
534 /* Make a heap segment. */
535 if (derive_heap_segment (exec_bfd
, &temp_bottom
, &temp_top
))
536 (*func
) (temp_bottom
, temp_top
- temp_bottom
,
537 1, /* Heap section will be readable. */
538 1, /* Heap section will be writable. */
539 0, /* Heap section will not be executable. */
540 1, /* Heap section will be modified. */
547 gcore_copy_callback (bfd
*obfd
, asection
*osec
, void *ignored
)
549 bfd_size_type size
, total_size
= bfd_section_size (obfd
, osec
);
551 struct cleanup
*old_chain
= NULL
;
554 /* Read-only sections are marked; we don't have to copy their contents. */
555 if ((bfd_get_section_flags (obfd
, osec
) & SEC_LOAD
) == 0)
558 /* Only interested in "load" sections. */
559 if (!startswith (bfd_section_name (obfd
, osec
), "load"))
562 size
= std::min (total_size
, (bfd_size_type
) MAX_COPY_BYTES
);
563 memhunk
= (gdb_byte
*) xmalloc (size
);
564 old_chain
= make_cleanup (xfree
, memhunk
);
566 while (total_size
> 0)
568 if (size
> total_size
)
571 if (target_read_memory (bfd_section_vma (obfd
, osec
) + offset
,
574 warning (_("Memory read failed for corefile "
575 "section, %s bytes at %s."),
577 paddress (target_gdbarch (), bfd_section_vma (obfd
, osec
)));
580 if (!bfd_set_section_contents (obfd
, osec
, memhunk
, offset
, size
))
582 warning (_("Failed to write corefile contents (%s)."),
583 bfd_errmsg (bfd_get_error ()));
591 do_cleanups (old_chain
); /* Frees MEMHUNK. */
595 gcore_memory_sections (bfd
*obfd
)
597 /* Try gdbarch method first, then fall back to target method. */
598 if (!gdbarch_find_memory_regions_p (target_gdbarch ())
599 || gdbarch_find_memory_regions (target_gdbarch (),
600 gcore_create_callback
, obfd
) != 0)
602 if (target_find_memory_regions (gcore_create_callback
, obfd
) != 0)
603 return 0; /* FIXME: error return/msg? */
606 /* Record phdrs for section-to-segment mapping. */
607 bfd_map_over_sections (obfd
, make_output_phdrs
, NULL
);
609 /* Copy memory region contents. */
610 bfd_map_over_sections (obfd
, gcore_copy_callback
, NULL
);
615 /* Provide a prototype to silence -Wmissing-prototypes. */
616 extern initialize_file_ftype _initialize_gcore
;
619 _initialize_gcore (void)
621 add_com ("generate-core-file", class_files
, gcore_command
, _("\
622 Save a core file with the current state of the debugged process.\n\
623 Argument is optional filename. Default filename is 'core.<process_id>'."));
625 add_com_alias ("gcore", "generate-core-file", class_files
, 1);