1 /* Generate a core file for the inferior process.
3 Copyright (C) 2001-2020 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 "gdbsupport/gdb_unlinker.h"
39 #include "gdbsupport/byte-vector.h"
40 #include "gdbsupport/scope-exit.h"
42 /* The largest amount of memory to read from the target at once. We
43 must throttle it to limit the amount of memory used by GDB during
44 generate-core-file for programs with large resident data. */
45 #define MAX_COPY_BYTES (1024 * 1024)
47 static const char *default_gcore_target (void);
48 static enum bfd_architecture
default_gcore_arch (void);
49 static unsigned long default_gcore_mach (void);
50 static int gcore_memory_sections (bfd
*);
52 /* create_gcore_bfd -- helper for gcore_command (exported).
53 Open a new bfd core file for output, and return the handle. */
56 create_gcore_bfd (const char *filename
)
58 gdb_bfd_ref_ptr
obfd (gdb_bfd_openw (filename
, default_gcore_target ()));
61 error (_("Failed to open '%s' for output."), filename
);
62 bfd_set_format (obfd
.get (), bfd_core
);
63 bfd_set_arch_mach (obfd
.get (), default_gcore_arch (), default_gcore_mach ());
67 /* write_gcore_file_1 -- do the actual work of write_gcore_file. */
70 write_gcore_file_1 (bfd
*obfd
)
72 gdb::unique_xmalloc_ptr
<char> note_data
;
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
.reset (target_make_corefile_notes (obfd
, ¬e_size
));
83 note_data
.reset (gdbarch_make_corefile_notes (target_gdbarch (), obfd
,
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 (note_sec
, 0);
99 bfd_set_section_alignment (note_sec
, 0);
100 bfd_set_section_size (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
.get (), 0,
109 warning (_("writing note section (%s)"), bfd_errmsg (bfd_get_error ()));
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 target_prepare_to_generate_core ();
119 SCOPE_EXIT
{ target_done_generating_core (); };
120 write_gcore_file_1 (obfd
);
123 /* gcore_command -- implements the 'gcore' command.
124 Generate a core file from the inferior process. */
127 gcore_command (const char *args
, int from_tty
)
129 gdb::unique_xmalloc_ptr
<char> corefilename
;
131 /* No use generating a corefile without a target process. */
132 if (!target_has_execution ())
136 corefilename
.reset (tilde_expand (args
));
139 /* Default corefile name is "core.PID". */
140 corefilename
.reset (xstrprintf ("core.%d", inferior_ptid
.pid ()));
144 fprintf_filtered (gdb_stdout
,
145 "Opening corefile '%s' for output.\n",
146 corefilename
.get ());
148 if (target_supports_dumpcore ())
149 target_dumpcore (corefilename
.get ());
152 /* Open the output file. */
153 gdb_bfd_ref_ptr
obfd (create_gcore_bfd (corefilename
.get ()));
155 /* Arrange to unlink the file on failure. */
156 gdb::unlinker
unlink_file (corefilename
.get ());
158 /* Call worker function. */
159 write_gcore_file (obfd
.get ());
165 fprintf_filtered (gdb_stdout
, "Saved corefile %s\n", corefilename
.get ());
169 default_gcore_mach (void)
171 #if 1 /* See if this even matters... */
175 const struct bfd_arch_info
*bfdarch
= gdbarch_bfd_arch_info (target_gdbarch ());
178 return bfdarch
->mach
;
179 if (exec_bfd
== NULL
)
180 error (_("Can't find default bfd machine type (need execfile)."));
182 return bfd_get_mach (exec_bfd
);
186 static enum bfd_architecture
187 default_gcore_arch (void)
189 const struct bfd_arch_info
*bfdarch
= gdbarch_bfd_arch_info (target_gdbarch ());
192 return bfdarch
->arch
;
193 if (exec_bfd
== NULL
)
194 error (_("Can't find bfd architecture for corefile (need execfile)."));
196 return bfd_get_arch (exec_bfd
);
200 default_gcore_target (void)
202 /* The gdbarch may define a target to use for core files. */
203 if (gdbarch_gcore_bfd_target_p (target_gdbarch ()))
204 return gdbarch_gcore_bfd_target (target_gdbarch ());
206 /* Otherwise, try to fall back to the exec_bfd target. This will probably
207 not work for non-ELF targets. */
208 if (exec_bfd
== NULL
)
211 return bfd_get_target (exec_bfd
);
214 /* Derive a reasonable stack segment by unwinding the target stack,
215 and store its limits in *BOTTOM and *TOP. Return non-zero if
219 derive_stack_segment (bfd_vma
*bottom
, bfd_vma
*top
)
221 struct frame_info
*fi
, *tmp_fi
;
226 /* Can't succeed without stack and registers. */
227 if (!target_has_stack () || !target_has_registers ())
230 /* Can't succeed without current frame. */
231 fi
= get_current_frame ();
235 /* Save frame pointer of TOS frame. */
236 *top
= get_frame_base (fi
);
237 /* If current stack pointer is more "inner", use that instead. */
238 if (gdbarch_inner_than (get_frame_arch (fi
), get_frame_sp (fi
), *top
))
239 *top
= get_frame_sp (fi
);
241 /* Find prev-most frame. */
242 while ((tmp_fi
= get_prev_frame (fi
)) != NULL
)
245 /* Save frame pointer of prev-most frame. */
246 *bottom
= get_frame_base (fi
);
248 /* Now canonicalize their order, so that BOTTOM is a lower address
249 (as opposed to a lower stack frame). */
262 /* call_target_sbrk --
263 helper function for derive_heap_segment. */
266 call_target_sbrk (int sbrk_arg
)
268 struct objfile
*sbrk_objf
;
269 struct gdbarch
*gdbarch
;
271 struct value
*target_sbrk_arg
;
272 struct value
*sbrk_fn
, *ret
;
275 if (lookup_minimal_symbol ("sbrk", NULL
, NULL
).minsym
!= NULL
)
277 sbrk_fn
= find_function_in_inferior ("sbrk", &sbrk_objf
);
281 else if (lookup_minimal_symbol ("_sbrk", NULL
, NULL
).minsym
!= NULL
)
283 sbrk_fn
= find_function_in_inferior ("_sbrk", &sbrk_objf
);
290 gdbarch
= sbrk_objf
->arch ();
291 target_sbrk_arg
= value_from_longest (builtin_type (gdbarch
)->builtin_int
,
293 gdb_assert (target_sbrk_arg
);
294 ret
= call_function_by_hand (sbrk_fn
, NULL
, target_sbrk_arg
);
298 tmp
= value_as_long (ret
);
299 if ((LONGEST
) tmp
<= 0 || (LONGEST
) tmp
== 0xffffffff)
306 /* Derive a reasonable heap segment for ABFD by looking at sbrk and
307 the static data sections. Store its limits in *BOTTOM and *TOP.
308 Return non-zero if successful. */
311 derive_heap_segment (bfd
*abfd
, bfd_vma
*bottom
, bfd_vma
*top
)
313 bfd_vma top_of_data_memory
= 0;
314 bfd_vma top_of_heap
= 0;
315 bfd_size_type sec_size
;
322 /* This function depends on being able to call a function in the
324 if (!target_has_execution ())
327 /* The following code assumes that the link map is arranged as
328 follows (low to high addresses):
330 ---------------------------------
332 ---------------------------------
333 | data sections (including bss) |
334 ---------------------------------
336 --------------------------------- */
338 for (sec
= abfd
->sections
; sec
; sec
= sec
->next
)
340 if (bfd_section_flags (sec
) & SEC_DATA
341 || strcmp (".bss", bfd_section_name (sec
)) == 0)
343 sec_vaddr
= bfd_section_vma (sec
);
344 sec_size
= bfd_section_size (sec
);
345 if (sec_vaddr
+ sec_size
> top_of_data_memory
)
346 top_of_data_memory
= sec_vaddr
+ sec_size
;
350 top_of_heap
= call_target_sbrk (0);
351 if (top_of_heap
== (bfd_vma
) 0)
354 /* Return results. */
355 if (top_of_heap
> top_of_data_memory
)
357 *bottom
= top_of_data_memory
;
362 /* No additional heap space needs to be saved. */
367 make_output_phdrs (bfd
*obfd
, asection
*osec
)
372 /* FIXME: these constants may only be applicable for ELF. */
373 if (startswith (bfd_section_name (osec
), "load"))
375 else if (startswith (bfd_section_name (osec
), "note"))
380 p_flags
|= PF_R
; /* Segment is readable. */
381 if (!(bfd_section_flags (osec
) & SEC_READONLY
))
382 p_flags
|= PF_W
; /* Segment is writable. */
383 if (bfd_section_flags (osec
) & SEC_CODE
)
384 p_flags
|= PF_X
; /* Segment is executable. */
386 bfd_record_phdr (obfd
, p_type
, 1, p_flags
, 0, 0, 0, 0, 1, &osec
);
389 /* find_memory_region_ftype implementation. DATA is 'bfd *' for the core file
393 gcore_create_callback (CORE_ADDR vaddr
, unsigned long size
, int read
,
394 int write
, int exec
, int modified
, void *data
)
396 bfd
*obfd
= (bfd
*) data
;
398 flagword flags
= SEC_ALLOC
| SEC_HAS_CONTENTS
| SEC_LOAD
;
400 /* If the memory segment has no permissions set, ignore it, otherwise
401 when we later try to access it for read/write, we'll get an error
402 or jam the kernel. */
403 if (read
== 0 && write
== 0 && exec
== 0 && modified
== 0)
407 fprintf_filtered (gdb_stdout
, "Ignore segment, %s bytes at %s\n",
408 plongest (size
), paddress (target_gdbarch (), vaddr
));
414 if (write
== 0 && modified
== 0 && !solib_keep_data_in_core (vaddr
, size
))
416 /* See if this region of memory lies inside a known file on disk.
417 If so, we can avoid copying its contents by clearing SEC_LOAD. */
418 struct obj_section
*objsec
;
420 for (objfile
*objfile
: current_program_space
->objfiles ())
421 ALL_OBJFILE_OSECTIONS (objfile
, objsec
)
423 bfd
*abfd
= objfile
->obfd
;
424 asection
*asec
= objsec
->the_bfd_section
;
425 bfd_vma align
= (bfd_vma
) 1 << bfd_section_alignment (asec
);
426 bfd_vma start
= obj_section_addr (objsec
) & -align
;
427 bfd_vma end
= (obj_section_endaddr (objsec
) + align
- 1) & -align
;
429 /* Match if either the entire memory region lies inside the
430 section (i.e. a mapping covering some pages of a large
431 segment) or the entire section lies inside the memory region
432 (i.e. a mapping covering multiple small sections).
434 This BFD was synthesized from reading target memory,
435 we don't want to omit that. */
436 if (objfile
->separate_debug_objfile_backlink
== NULL
437 && ((vaddr
>= start
&& vaddr
+ size
<= end
)
438 || (start
>= vaddr
&& end
<= vaddr
+ size
))
439 && !(bfd_get_file_flags (abfd
) & BFD_IN_MEMORY
))
441 flags
&= ~(SEC_LOAD
| SEC_HAS_CONTENTS
);
442 goto keep
; /* Break out of two nested for loops. */
450 flags
|= SEC_READONLY
;
457 osec
= bfd_make_section_anyway_with_flags (obfd
, "load", flags
);
460 warning (_("Couldn't make gcore segment: %s"),
461 bfd_errmsg (bfd_get_error ()));
467 fprintf_filtered (gdb_stdout
, "Save segment, %s bytes at %s\n",
468 plongest (size
), paddress (target_gdbarch (), vaddr
));
471 bfd_set_section_size (osec
, size
);
472 bfd_set_section_vma (osec
, vaddr
);
473 bfd_set_section_lma (osec
, 0);
478 objfile_find_memory_regions (struct target_ops
*self
,
479 find_memory_region_ftype func
, void *obfd
)
481 /* Use objfile data to create memory sections. */
482 struct obj_section
*objsec
;
483 bfd_vma temp_bottom
, temp_top
;
485 /* Call callback function for each objfile section. */
486 for (objfile
*objfile
: current_program_space
->objfiles ())
487 ALL_OBJFILE_OSECTIONS (objfile
, objsec
)
489 asection
*isec
= objsec
->the_bfd_section
;
490 flagword flags
= bfd_section_flags (isec
);
492 /* Separate debug info files are irrelevant for gcore. */
493 if (objfile
->separate_debug_objfile_backlink
!= NULL
)
496 if ((flags
& SEC_ALLOC
) || (flags
& SEC_LOAD
))
498 int size
= bfd_section_size (isec
);
501 ret
= (*func
) (obj_section_addr (objsec
), size
,
502 1, /* All sections will be readable. */
503 (flags
& SEC_READONLY
) == 0, /* Writable. */
504 (flags
& SEC_CODE
) != 0, /* Executable. */
505 1, /* MODIFIED is unknown, pass it as true. */
512 /* Make a stack segment. */
513 if (derive_stack_segment (&temp_bottom
, &temp_top
))
514 (*func
) (temp_bottom
, temp_top
- temp_bottom
,
515 1, /* Stack section will be readable. */
516 1, /* Stack section will be writable. */
517 0, /* Stack section will not be executable. */
518 1, /* Stack section will be modified. */
521 /* Make a heap segment. */
522 if (derive_heap_segment (exec_bfd
, &temp_bottom
, &temp_top
))
523 (*func
) (temp_bottom
, temp_top
- temp_bottom
,
524 1, /* Heap section will be readable. */
525 1, /* Heap section will be writable. */
526 0, /* Heap section will not be executable. */
527 1, /* Heap section will be modified. */
534 gcore_copy_callback (bfd
*obfd
, asection
*osec
)
536 bfd_size_type size
, total_size
= bfd_section_size (osec
);
539 /* Read-only sections are marked; we don't have to copy their contents. */
540 if ((bfd_section_flags (osec
) & SEC_LOAD
) == 0)
543 /* Only interested in "load" sections. */
544 if (!startswith (bfd_section_name (osec
), "load"))
547 size
= std::min (total_size
, (bfd_size_type
) MAX_COPY_BYTES
);
548 gdb::byte_vector
memhunk (size
);
550 while (total_size
> 0)
552 if (size
> total_size
)
555 if (target_read_memory (bfd_section_vma (osec
) + offset
,
556 memhunk
.data (), size
) != 0)
558 warning (_("Memory read failed for corefile "
559 "section, %s bytes at %s."),
561 paddress (target_gdbarch (), bfd_section_vma (osec
)));
564 if (!bfd_set_section_contents (obfd
, osec
, memhunk
.data (),
567 warning (_("Failed to write corefile contents (%s)."),
568 bfd_errmsg (bfd_get_error ()));
578 gcore_memory_sections (bfd
*obfd
)
580 /* Try gdbarch method first, then fall back to target method. */
581 if (!gdbarch_find_memory_regions_p (target_gdbarch ())
582 || gdbarch_find_memory_regions (target_gdbarch (),
583 gcore_create_callback
, obfd
) != 0)
585 if (target_find_memory_regions (gcore_create_callback
, obfd
) != 0)
586 return 0; /* FIXME: error return/msg? */
589 /* Record phdrs for section-to-segment mapping. */
590 for (asection
*sect
: gdb_bfd_sections (obfd
))
591 make_output_phdrs (obfd
, sect
);
593 /* Copy memory region contents. */
594 for (asection
*sect
: gdb_bfd_sections (obfd
))
595 gcore_copy_callback (obfd
, sect
);
600 void _initialize_gcore ();
604 add_com ("generate-core-file", class_files
, gcore_command
, _("\
605 Save a core file with the current state of the debugged process.\n\
606 Usage: generate-core-file [FILENAME]\n\
607 Argument is optional filename. Default filename is 'core.PROCESS_ID'."));
609 add_com_alias ("gcore", "generate-core-file", class_files
, 1);