1 /* Cache and manage frames for GDB, the GNU debugger.
3 Copyright (C) 1986-2021 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/>. */
24 #include "inferior.h" /* for inferior_ptid */
26 #include "user-regs.h"
27 #include "gdb_obstack.h"
28 #include "dummy-frame.h"
29 #include "sentinel-frame.h"
33 #include "frame-unwind.h"
34 #include "frame-base.h"
37 #include "observable.h"
39 #include "gdbthread.h"
41 #include "inline-frame.h"
42 #include "tracepoint.h"
45 #include "cli/cli-option.h"
47 /* The sentinel frame terminates the innermost end of the frame chain.
48 If unwound, it returns the information needed to construct an
51 The current frame, which is the innermost frame, can be found at
52 sentinel_frame->prev. */
54 static struct frame_info
*sentinel_frame
;
56 /* Number of calls to reinit_frame_cache. */
57 static unsigned int frame_cache_generation
= 0;
62 get_frame_cache_generation ()
64 return frame_cache_generation
;
67 /* The values behind the global "set backtrace ..." settings. */
68 set_backtrace_options user_set_backtrace_options
;
70 static struct frame_info
*get_prev_frame_raw (struct frame_info
*this_frame
);
71 static const char *frame_stop_reason_symbol_string (enum unwind_stop_reason reason
);
73 /* Status of some values cached in the frame_info object. */
75 enum cached_copy_status
77 /* Value is unknown. */
80 /* We have a value. */
83 /* Value was not saved. */
86 /* Value is unavailable. */
90 enum class frame_id_status
92 /* Frame id is not computed. */
95 /* Frame id is being computed (compute_frame_id is active). */
98 /* Frame id has been computed. */
102 /* We keep a cache of stack frames, each of which is a "struct
103 frame_info". The innermost one gets allocated (in
104 wait_for_inferior) each time the inferior stops; sentinel_frame
105 points to it. Additional frames get allocated (in get_prev_frame)
106 as needed, and are chained through the next and prev fields. Any
107 time that the frame cache becomes invalid (most notably when we
108 execute something, but also if we change how we interpret the
109 frames (e.g. "set heuristic-fence-post" in mips-tdep.c, or anything
110 which reads new symbols)), we should call reinit_frame_cache. */
114 /* Return a string representation of this frame. */
115 std::string
to_string () const;
117 /* Level of this frame. The inner-most (youngest) frame is at level
118 0. As you move towards the outer-most (oldest) frame, the level
119 increases. This is a cached value. It could just as easily be
120 computed by counting back from the selected frame to the inner
122 /* NOTE: cagney/2002-04-05: Perhaps a level of ``-1'' should be
123 reserved to indicate a bogus frame - one that has been created
124 just to keep GDB happy (GDB always needs a frame). For the
125 moment leave this as speculation. */
128 /* The frame's program space. */
129 struct program_space
*pspace
;
131 /* The frame's address space. */
132 const address_space
*aspace
;
134 /* The frame's low-level unwinder and corresponding cache. The
135 low-level unwinder is responsible for unwinding register values
136 for the previous frame. The low-level unwind methods are
137 selected based on the presence, or otherwise, of register unwind
138 information such as CFI. */
139 void *prologue_cache
;
140 const struct frame_unwind
*unwind
;
142 /* Cached copy of the previous frame's architecture. */
146 struct gdbarch
*arch
;
149 /* Cached copy of the previous frame's resume address. */
151 cached_copy_status status
;
152 /* Did VALUE require unmasking when being read. */
157 /* Cached copy of the previous frame's function address. */
161 cached_copy_status status
;
164 /* This frame's ID. */
168 struct frame_id value
;
171 /* The frame's high-level base methods, and corresponding cache.
172 The high level base methods are selected based on the frame's
174 const struct frame_base
*base
;
177 /* Pointers to the next (down, inner, younger) and previous (up,
178 outer, older) frame_info's in the frame cache. */
179 struct frame_info
*next
; /* down, inner, younger */
181 struct frame_info
*prev
; /* up, outer, older */
183 /* The reason why we could not set PREV, or UNWIND_NO_REASON if we
184 could. Only valid when PREV_P is set. */
185 enum unwind_stop_reason stop_reason
;
187 /* A frame specific string describing the STOP_REASON in more detail.
188 Only valid when PREV_P is set, but even then may still be NULL. */
189 const char *stop_string
;
195 set_frame_previous_pc_masked (struct frame_info
*frame
)
197 frame
->prev_pc
.masked
= true;
203 get_frame_pc_masked (const struct frame_info
*frame
)
205 gdb_assert (frame
->next
!= nullptr);
206 gdb_assert (frame
->next
->prev_pc
.status
== CC_VALUE
);
208 return frame
->next
->prev_pc
.masked
;
211 /* A frame stash used to speed up frame lookups. Create a hash table
212 to stash frames previously accessed from the frame cache for
213 quicker subsequent retrieval. The hash table is emptied whenever
214 the frame cache is invalidated. */
216 static htab_t frame_stash
;
218 /* Internal function to calculate a hash from the frame_id addresses,
219 using as many valid addresses as possible. Frames below level 0
220 are not stored in the hash table. */
223 frame_addr_hash (const void *ap
)
225 const struct frame_info
*frame
= (const struct frame_info
*) ap
;
226 const struct frame_id f_id
= frame
->this_id
.value
;
229 gdb_assert (f_id
.stack_status
!= FID_STACK_INVALID
231 || f_id
.special_addr_p
);
233 if (f_id
.stack_status
== FID_STACK_VALID
)
234 hash
= iterative_hash (&f_id
.stack_addr
,
235 sizeof (f_id
.stack_addr
), hash
);
236 if (f_id
.code_addr_p
)
237 hash
= iterative_hash (&f_id
.code_addr
,
238 sizeof (f_id
.code_addr
), hash
);
239 if (f_id
.special_addr_p
)
240 hash
= iterative_hash (&f_id
.special_addr
,
241 sizeof (f_id
.special_addr
), hash
);
246 /* Internal equality function for the hash table. This function
247 defers equality operations to frame_id_eq. */
250 frame_addr_hash_eq (const void *a
, const void *b
)
252 const struct frame_info
*f_entry
= (const struct frame_info
*) a
;
253 const struct frame_info
*f_element
= (const struct frame_info
*) b
;
255 return frame_id_eq (f_entry
->this_id
.value
,
256 f_element
->this_id
.value
);
259 /* Internal function to create the frame_stash hash table. 100 seems
260 to be a good compromise to start the hash table at. */
263 frame_stash_create (void)
265 frame_stash
= htab_create (100,
271 /* Internal function to add a frame to the frame_stash hash table.
272 Returns false if a frame with the same ID was already stashed, true
276 frame_stash_add (frame_info
*frame
)
278 /* Do not try to stash the sentinel frame. */
279 gdb_assert (frame
->level
>= 0);
281 frame_info
**slot
= (struct frame_info
**) htab_find_slot (frame_stash
,
284 /* If we already have a frame in the stack with the same id, we
285 either have a stack cycle (corrupted stack?), or some bug
286 elsewhere in GDB. In any case, ignore the duplicate and return
287 an indication to the caller. */
288 if (*slot
!= nullptr)
295 /* Internal function to search the frame stash for an entry with the
296 given frame ID. If found, return that frame. Otherwise return
299 static struct frame_info
*
300 frame_stash_find (struct frame_id id
)
302 struct frame_info dummy
;
303 struct frame_info
*frame
;
305 dummy
.this_id
.value
= id
;
306 frame
= (struct frame_info
*) htab_find (frame_stash
, &dummy
);
310 /* Internal function to invalidate the frame stash by removing all
311 entries in it. This only occurs when the frame cache is
315 frame_stash_invalidate (void)
317 htab_empty (frame_stash
);
321 scoped_restore_selected_frame::scoped_restore_selected_frame ()
323 m_lang
= current_language
->la_language
;
324 save_selected_frame (&m_fid
, &m_level
);
328 scoped_restore_selected_frame::~scoped_restore_selected_frame ()
330 restore_selected_frame (m_fid
, m_level
);
331 set_language (m_lang
);
334 /* Flag to control debugging. */
339 show_frame_debug (struct ui_file
*file
, int from_tty
,
340 struct cmd_list_element
*c
, const char *value
)
342 fprintf_filtered (file
, _("Frame debugging is %s.\n"), value
);
345 /* Implementation of "show backtrace past-main". */
348 show_backtrace_past_main (struct ui_file
*file
, int from_tty
,
349 struct cmd_list_element
*c
, const char *value
)
351 fprintf_filtered (file
,
352 _("Whether backtraces should "
353 "continue past \"main\" is %s.\n"),
357 /* Implementation of "show backtrace past-entry". */
360 show_backtrace_past_entry (struct ui_file
*file
, int from_tty
,
361 struct cmd_list_element
*c
, const char *value
)
363 fprintf_filtered (file
, _("Whether backtraces should continue past the "
364 "entry point of a program is %s.\n"),
368 /* Implementation of "show backtrace limit". */
371 show_backtrace_limit (struct ui_file
*file
, int from_tty
,
372 struct cmd_list_element
*c
, const char *value
)
374 fprintf_filtered (file
,
375 _("An upper bound on the number "
376 "of backtrace levels is %s.\n"),
383 frame_id::to_string () const
385 const struct frame_id
&id
= *this;
387 std::string res
= "{";
389 if (id
.stack_status
== FID_STACK_INVALID
)
391 else if (id
.stack_status
== FID_STACK_UNAVAILABLE
)
392 res
+= "stack=<unavailable>";
393 else if (id
.stack_status
== FID_STACK_SENTINEL
)
394 res
+= "stack=<sentinel>";
395 else if (id
.stack_status
== FID_STACK_OUTER
)
396 res
+= "stack=<outer>";
398 res
+= std::string ("stack=") + hex_string (id
.stack_addr
);
400 /* Helper function to format 'N=A' if P is true, otherwise '!N'. */
401 auto field_to_string
= [] (const char *n
, bool p
, CORE_ADDR a
) -> std::string
404 return std::string (n
) + "=" + core_addr_to_string (a
);
406 return std::string ("!") + std::string (n
);
409 res
+= (std::string (",")
410 + field_to_string ("code", id
.code_addr_p
, id
.code_addr
)
412 + field_to_string ("special", id
.special_addr_p
, id
.special_addr
));
414 if (id
.artificial_depth
)
415 res
+= ",artificial=" + std::to_string (id
.artificial_depth
);
420 /* Return a string representation of TYPE. */
423 frame_type_str (frame_type type
)
428 return "NORMAL_FRAME";
431 return "DUMMY_FRAME";
434 return "INLINE_FRAME";
437 return "TAILCALL_FRAME";
440 return "SIGTRAMP_FRAME";
446 return "SENTINEL_FRAME";
449 return "<unknown type>";
453 /* See struct frame_info. */
456 frame_info::to_string () const
458 const frame_info
*fi
= this;
462 res
+= string_printf ("{level=%d,", fi
->level
);
464 if (fi
->unwind
!= NULL
)
465 res
+= string_printf ("type=%s,", frame_type_str (fi
->unwind
->type
));
467 res
+= "type=<unknown>,";
469 if (fi
->unwind
!= NULL
)
470 res
+= string_printf ("unwind=%p,", host_address_to_string (fi
->unwind
));
472 res
+= "unwind=<unknown>,";
474 if (fi
->next
== NULL
|| fi
->next
->prev_pc
.status
== CC_UNKNOWN
)
475 res
+= "pc=<unknown>,";
476 else if (fi
->next
->prev_pc
.status
== CC_VALUE
)
477 res
+= string_printf ("pc=%s%s,", hex_string (fi
->next
->prev_pc
.value
),
478 fi
->next
->prev_pc
.masked
? "[PAC]" : "");
479 else if (fi
->next
->prev_pc
.status
== CC_NOT_SAVED
)
480 res
+= "pc=<not saved>,";
481 else if (fi
->next
->prev_pc
.status
== CC_UNAVAILABLE
)
482 res
+= "pc=<unavailable>,";
484 if (fi
->this_id
.p
== frame_id_status::NOT_COMPUTED
)
485 res
+= "id=<not computed>,";
486 else if (fi
->this_id
.p
== frame_id_status::COMPUTING
)
487 res
+= "id=<computing>,";
489 res
+= string_printf ("id=%s,", fi
->this_id
.value
.to_string ().c_str ());
491 if (fi
->next
!= NULL
&& fi
->next
->prev_func
.status
== CC_VALUE
)
492 res
+= string_printf ("func=%s", hex_string (fi
->next
->prev_func
.addr
));
494 res
+= "func=<unknown>";
501 /* Given FRAME, return the enclosing frame as found in real frames read-in from
502 inferior memory. Skip any previous frames which were made up by GDB.
503 Return FRAME if FRAME is a non-artificial frame.
504 Return NULL if FRAME is the start of an artificial-only chain. */
506 static struct frame_info
*
507 skip_artificial_frames (struct frame_info
*frame
)
509 /* Note we use get_prev_frame_always, and not get_prev_frame. The
510 latter will truncate the frame chain, leading to this function
511 unintentionally returning a null_frame_id (e.g., when the user
512 sets a backtrace limit).
514 Note that for record targets we may get a frame chain that consists
515 of artificial frames only. */
516 while (get_frame_type (frame
) == INLINE_FRAME
517 || get_frame_type (frame
) == TAILCALL_FRAME
)
519 frame
= get_prev_frame_always (frame
);
528 skip_unwritable_frames (struct frame_info
*frame
)
530 while (gdbarch_code_of_frame_writable (get_frame_arch (frame
), frame
) == 0)
532 frame
= get_prev_frame (frame
);
543 skip_tailcall_frames (struct frame_info
*frame
)
545 while (get_frame_type (frame
) == TAILCALL_FRAME
)
547 /* Note that for record targets we may get a frame chain that consists of
548 tailcall frames only. */
549 frame
= get_prev_frame (frame
);
557 /* Compute the frame's uniq ID that can be used to, later, re-find the
561 compute_frame_id (struct frame_info
*fi
)
563 FRAME_SCOPED_DEBUG_ENTER_EXIT
;
565 gdb_assert (fi
->this_id
.p
== frame_id_status::NOT_COMPUTED
);
567 unsigned int entry_generation
= get_frame_cache_generation ();
571 /* Mark this frame's id as "being computed. */
572 fi
->this_id
.p
= frame_id_status::COMPUTING
;
574 frame_debug_printf ("fi=%d", fi
->level
);
576 /* Find the unwinder. */
577 if (fi
->unwind
== NULL
)
578 frame_unwind_find_by_frame (fi
, &fi
->prologue_cache
);
580 /* Find THIS frame's ID. */
581 /* Default to outermost if no ID is found. */
582 fi
->this_id
.value
= outer_frame_id
;
583 fi
->unwind
->this_id (fi
, &fi
->prologue_cache
, &fi
->this_id
.value
);
584 gdb_assert (frame_id_p (fi
->this_id
.value
));
586 /* Mark this frame's id as "computed". */
587 fi
->this_id
.p
= frame_id_status::COMPUTED
;
589 frame_debug_printf (" -> %s", fi
->this_id
.value
.to_string ().c_str ());
591 catch (const gdb_exception
&ex
)
593 /* On error, revert the frame id status to not computed. If the frame
594 cache generation changed, the frame object doesn't exist anymore, so
596 if (get_frame_cache_generation () == entry_generation
)
597 fi
->this_id
.p
= frame_id_status::NOT_COMPUTED
;
603 /* Return a frame uniq ID that can be used to, later, re-find the
607 get_frame_id (struct frame_info
*fi
)
610 return null_frame_id
;
612 /* It's always invalid to try to get a frame's id while it is being
614 gdb_assert (fi
->this_id
.p
!= frame_id_status::COMPUTING
);
616 if (fi
->this_id
.p
== frame_id_status::NOT_COMPUTED
)
618 /* If we haven't computed the frame id yet, then it must be that
619 this is the current frame. Compute it now, and stash the
620 result. The IDs of other frames are computed as soon as
621 they're created, in order to detect cycles. See
622 get_prev_frame_if_no_cycle. */
623 gdb_assert (fi
->level
== 0);
626 compute_frame_id (fi
);
628 /* Since this is the first frame in the chain, this should
630 bool stashed
= frame_stash_add (fi
);
631 gdb_assert (stashed
);
634 return fi
->this_id
.value
;
638 get_stack_frame_id (struct frame_info
*next_frame
)
640 return get_frame_id (skip_artificial_frames (next_frame
));
644 frame_unwind_caller_id (struct frame_info
*next_frame
)
646 struct frame_info
*this_frame
;
648 /* Use get_prev_frame_always, and not get_prev_frame. The latter
649 will truncate the frame chain, leading to this function
650 unintentionally returning a null_frame_id (e.g., when a caller
651 requests the frame ID of "main()"s caller. */
653 next_frame
= skip_artificial_frames (next_frame
);
654 if (next_frame
== NULL
)
655 return null_frame_id
;
657 this_frame
= get_prev_frame_always (next_frame
);
659 return get_frame_id (skip_artificial_frames (this_frame
));
661 return null_frame_id
;
664 const struct frame_id null_frame_id
= { 0 }; /* All zeros. */
665 const struct frame_id sentinel_frame_id
= { 0, 0, 0, FID_STACK_SENTINEL
, 0, 1, 0 };
666 const struct frame_id outer_frame_id
= { 0, 0, 0, FID_STACK_OUTER
, 0, 1, 0 };
669 frame_id_build_special (CORE_ADDR stack_addr
, CORE_ADDR code_addr
,
670 CORE_ADDR special_addr
)
672 struct frame_id id
= null_frame_id
;
674 id
.stack_addr
= stack_addr
;
675 id
.stack_status
= FID_STACK_VALID
;
676 id
.code_addr
= code_addr
;
677 id
.code_addr_p
= true;
678 id
.special_addr
= special_addr
;
679 id
.special_addr_p
= true;
686 frame_id_build_unavailable_stack (CORE_ADDR code_addr
)
688 struct frame_id id
= null_frame_id
;
690 id
.stack_status
= FID_STACK_UNAVAILABLE
;
691 id
.code_addr
= code_addr
;
692 id
.code_addr_p
= true;
699 frame_id_build_unavailable_stack_special (CORE_ADDR code_addr
,
700 CORE_ADDR special_addr
)
702 struct frame_id id
= null_frame_id
;
704 id
.stack_status
= FID_STACK_UNAVAILABLE
;
705 id
.code_addr
= code_addr
;
706 id
.code_addr_p
= true;
707 id
.special_addr
= special_addr
;
708 id
.special_addr_p
= true;
713 frame_id_build (CORE_ADDR stack_addr
, CORE_ADDR code_addr
)
715 struct frame_id id
= null_frame_id
;
717 id
.stack_addr
= stack_addr
;
718 id
.stack_status
= FID_STACK_VALID
;
719 id
.code_addr
= code_addr
;
720 id
.code_addr_p
= true;
725 frame_id_build_wild (CORE_ADDR stack_addr
)
727 struct frame_id id
= null_frame_id
;
729 id
.stack_addr
= stack_addr
;
730 id
.stack_status
= FID_STACK_VALID
;
735 frame_id_p (frame_id l
)
737 /* The frame is valid iff it has a valid stack address. */
738 bool p
= l
.stack_status
!= FID_STACK_INVALID
;
740 frame_debug_printf ("l=%s -> %d", l
.to_string ().c_str (), p
);
746 frame_id_artificial_p (frame_id l
)
751 return l
.artificial_depth
!= 0;
755 frame_id_eq (frame_id l
, frame_id r
)
759 if (l
.stack_status
== FID_STACK_INVALID
760 || r
.stack_status
== FID_STACK_INVALID
)
761 /* Like a NaN, if either ID is invalid, the result is false.
762 Note that a frame ID is invalid iff it is the null frame ID. */
764 else if (l
.stack_status
!= r
.stack_status
|| l
.stack_addr
!= r
.stack_addr
)
765 /* If .stack addresses are different, the frames are different. */
767 else if (l
.code_addr_p
&& r
.code_addr_p
&& l
.code_addr
!= r
.code_addr
)
768 /* An invalid code addr is a wild card. If .code addresses are
769 different, the frames are different. */
771 else if (l
.special_addr_p
&& r
.special_addr_p
772 && l
.special_addr
!= r
.special_addr
)
773 /* An invalid special addr is a wild card (or unused). Otherwise
774 if special addresses are different, the frames are different. */
776 else if (l
.artificial_depth
!= r
.artificial_depth
)
777 /* If artificial depths are different, the frames must be different. */
780 /* Frames are equal. */
783 frame_debug_printf ("l=%s, r=%s -> %d",
784 l
.to_string ().c_str (), r
.to_string ().c_str (), eq
);
789 /* Safety net to check whether frame ID L should be inner to
790 frame ID R, according to their stack addresses.
792 This method cannot be used to compare arbitrary frames, as the
793 ranges of valid stack addresses may be discontiguous (e.g. due
796 However, it can be used as safety net to discover invalid frame
797 IDs in certain circumstances. Assuming that NEXT is the immediate
798 inner frame to THIS and that NEXT and THIS are both NORMAL frames:
800 * The stack address of NEXT must be inner-than-or-equal to the stack
803 Therefore, if frame_id_inner (THIS, NEXT) holds, some unwind
806 * If NEXT and THIS have different stack addresses, no other frame
807 in the frame chain may have a stack address in between.
809 Therefore, if frame_id_inner (TEST, THIS) holds, but
810 frame_id_inner (TEST, NEXT) does not hold, TEST cannot refer
811 to a valid frame in the frame chain.
813 The sanity checks above cannot be performed when a SIGTRAMP frame
814 is involved, because signal handlers might be executed on a different
815 stack than the stack used by the routine that caused the signal
816 to be raised. This can happen for instance when a thread exceeds
817 its maximum stack size. In this case, certain compilers implement
818 a stack overflow strategy that cause the handler to be run on a
822 frame_id_inner (struct gdbarch
*gdbarch
, struct frame_id l
, struct frame_id r
)
826 if (l
.stack_status
!= FID_STACK_VALID
|| r
.stack_status
!= FID_STACK_VALID
)
827 /* Like NaN, any operation involving an invalid ID always fails.
828 Likewise if either ID has an unavailable stack address. */
830 else if (l
.artificial_depth
> r
.artificial_depth
831 && l
.stack_addr
== r
.stack_addr
832 && l
.code_addr_p
== r
.code_addr_p
833 && l
.special_addr_p
== r
.special_addr_p
834 && l
.special_addr
== r
.special_addr
)
836 /* Same function, different inlined functions. */
837 const struct block
*lb
, *rb
;
839 gdb_assert (l
.code_addr_p
&& r
.code_addr_p
);
841 lb
= block_for_pc (l
.code_addr
);
842 rb
= block_for_pc (r
.code_addr
);
844 if (lb
== NULL
|| rb
== NULL
)
845 /* Something's gone wrong. */
848 /* This will return true if LB and RB are the same block, or
849 if the block with the smaller depth lexically encloses the
850 block with the greater depth. */
851 inner
= contained_in (lb
, rb
);
854 /* Only return non-zero when strictly inner than. Note that, per
855 comment in "frame.h", there is some fuzz here. Frameless
856 functions are not strictly inner than (same .stack but
857 different .code and/or .special address). */
858 inner
= gdbarch_inner_than (gdbarch
, l
.stack_addr
, r
.stack_addr
);
860 frame_debug_printf ("is l=%s inner than r=%s? %d",
861 l
.to_string ().c_str (), r
.to_string ().c_str (),
868 frame_find_by_id (struct frame_id id
)
870 struct frame_info
*frame
, *prev_frame
;
872 /* ZERO denotes the null frame, let the caller decide what to do
873 about it. Should it instead return get_current_frame()? */
874 if (!frame_id_p (id
))
877 /* Check for the sentinel frame. */
878 if (frame_id_eq (id
, sentinel_frame_id
))
879 return sentinel_frame
;
881 /* Try using the frame stash first. Finding it there removes the need
882 to perform the search by looping over all frames, which can be very
883 CPU-intensive if the number of frames is very high (the loop is O(n)
884 and get_prev_frame performs a series of checks that are relatively
885 expensive). This optimization is particularly useful when this function
886 is called from another function (such as value_fetch_lazy, case
887 VALUE_LVAL (val) == lval_register) which already loops over all frames,
888 making the overall behavior O(n^2). */
889 frame
= frame_stash_find (id
);
893 for (frame
= get_current_frame (); ; frame
= prev_frame
)
895 struct frame_id self
= get_frame_id (frame
);
897 if (frame_id_eq (id
, self
))
898 /* An exact match. */
901 prev_frame
= get_prev_frame (frame
);
905 /* As a safety net to avoid unnecessary backtracing while trying
906 to find an invalid ID, we check for a common situation where
907 we can detect from comparing stack addresses that no other
908 frame in the current frame chain can have this ID. See the
909 comment at frame_id_inner for details. */
910 if (get_frame_type (frame
) == NORMAL_FRAME
911 && !frame_id_inner (get_frame_arch (frame
), id
, self
)
912 && frame_id_inner (get_frame_arch (prev_frame
), id
,
913 get_frame_id (prev_frame
)))
920 frame_unwind_pc (struct frame_info
*this_frame
)
922 if (this_frame
->prev_pc
.status
== CC_UNKNOWN
)
924 struct gdbarch
*prev_gdbarch
;
928 /* The right way. The `pure' way. The one true way. This
929 method depends solely on the register-unwind code to
930 determine the value of registers in THIS frame, and hence
931 the value of this frame's PC (resume address). A typical
932 implementation is no more than:
934 frame_unwind_register (this_frame, ISA_PC_REGNUM, buf);
935 return extract_unsigned_integer (buf, size of ISA_PC_REGNUM);
937 Note: this method is very heavily dependent on a correct
938 register-unwind implementation, it pays to fix that
939 method first; this method is frame type agnostic, since
940 it only deals with register values, it works with any
941 frame. This is all in stark contrast to the old
942 FRAME_SAVED_PC which would try to directly handle all the
943 different ways that a PC could be unwound. */
944 prev_gdbarch
= frame_unwind_arch (this_frame
);
948 pc
= gdbarch_unwind_pc (prev_gdbarch
, this_frame
);
951 catch (const gdb_exception_error
&ex
)
953 if (ex
.error
== NOT_AVAILABLE_ERROR
)
955 this_frame
->prev_pc
.status
= CC_UNAVAILABLE
;
957 frame_debug_printf ("this_frame=%d -> <unavailable>",
960 else if (ex
.error
== OPTIMIZED_OUT_ERROR
)
962 this_frame
->prev_pc
.status
= CC_NOT_SAVED
;
964 frame_debug_printf ("this_frame=%d -> <not saved>",
973 this_frame
->prev_pc
.value
= pc
;
974 this_frame
->prev_pc
.status
= CC_VALUE
;
976 frame_debug_printf ("this_frame=%d -> %s",
978 hex_string (this_frame
->prev_pc
.value
));
982 if (this_frame
->prev_pc
.status
== CC_VALUE
)
983 return this_frame
->prev_pc
.value
;
984 else if (this_frame
->prev_pc
.status
== CC_UNAVAILABLE
)
985 throw_error (NOT_AVAILABLE_ERROR
, _("PC not available"));
986 else if (this_frame
->prev_pc
.status
== CC_NOT_SAVED
)
987 throw_error (OPTIMIZED_OUT_ERROR
, _("PC not saved"));
989 internal_error (__FILE__
, __LINE__
,
990 "unexpected prev_pc status: %d",
991 (int) this_frame
->prev_pc
.status
);
995 frame_unwind_caller_pc (struct frame_info
*this_frame
)
997 this_frame
= skip_artificial_frames (this_frame
);
999 /* We must have a non-artificial frame. The caller is supposed to check
1000 the result of frame_unwind_caller_id (), which returns NULL_FRAME_ID
1002 gdb_assert (this_frame
!= NULL
);
1004 return frame_unwind_pc (this_frame
);
1008 get_frame_func_if_available (frame_info
*this_frame
, CORE_ADDR
*pc
)
1010 struct frame_info
*next_frame
= this_frame
->next
;
1012 if (next_frame
->prev_func
.status
== CC_UNKNOWN
)
1014 CORE_ADDR addr_in_block
;
1016 /* Make certain that this, and not the adjacent, function is
1018 if (!get_frame_address_in_block_if_available (this_frame
, &addr_in_block
))
1020 next_frame
->prev_func
.status
= CC_UNAVAILABLE
;
1022 frame_debug_printf ("this_frame=%d -> unavailable",
1027 next_frame
->prev_func
.status
= CC_VALUE
;
1028 next_frame
->prev_func
.addr
= get_pc_function_start (addr_in_block
);
1030 frame_debug_printf ("this_frame=%d -> %s",
1032 hex_string (next_frame
->prev_func
.addr
));
1036 if (next_frame
->prev_func
.status
== CC_UNAVAILABLE
)
1043 gdb_assert (next_frame
->prev_func
.status
== CC_VALUE
);
1045 *pc
= next_frame
->prev_func
.addr
;
1051 get_frame_func (struct frame_info
*this_frame
)
1055 if (!get_frame_func_if_available (this_frame
, &pc
))
1056 throw_error (NOT_AVAILABLE_ERROR
, _("PC not available"));
1061 std::unique_ptr
<readonly_detached_regcache
>
1062 frame_save_as_regcache (struct frame_info
*this_frame
)
1064 auto cooked_read
= [this_frame
] (int regnum
, gdb_byte
*buf
)
1066 if (!deprecated_frame_register_read (this_frame
, regnum
, buf
))
1067 return REG_UNAVAILABLE
;
1072 std::unique_ptr
<readonly_detached_regcache
> regcache
1073 (new readonly_detached_regcache (get_frame_arch (this_frame
), cooked_read
));
1079 frame_pop (struct frame_info
*this_frame
)
1081 struct frame_info
*prev_frame
;
1083 if (get_frame_type (this_frame
) == DUMMY_FRAME
)
1085 /* Popping a dummy frame involves restoring more than just registers.
1086 dummy_frame_pop does all the work. */
1087 dummy_frame_pop (get_frame_id (this_frame
), inferior_thread ());
1091 /* Ensure that we have a frame to pop to. */
1092 prev_frame
= get_prev_frame_always (this_frame
);
1095 error (_("Cannot pop the initial frame."));
1097 /* Ignore TAILCALL_FRAME type frames, they were executed already before
1098 entering THISFRAME. */
1099 prev_frame
= skip_tailcall_frames (prev_frame
);
1101 if (prev_frame
== NULL
)
1102 error (_("Cannot find the caller frame."));
1104 /* Make a copy of all the register values unwound from this frame.
1105 Save them in a scratch buffer so that there isn't a race between
1106 trying to extract the old values from the current regcache while
1107 at the same time writing new values into that same cache. */
1108 std::unique_ptr
<readonly_detached_regcache
> scratch
1109 = frame_save_as_regcache (prev_frame
);
1111 /* FIXME: cagney/2003-03-16: It should be possible to tell the
1112 target's register cache that it is about to be hit with a burst
1113 register transfer and that the sequence of register writes should
1114 be batched. The pair target_prepare_to_store() and
1115 target_store_registers() kind of suggest this functionality.
1116 Unfortunately, they don't implement it. Their lack of a formal
1117 definition can lead to targets writing back bogus values
1118 (arguably a bug in the target code mind). */
1119 /* Now copy those saved registers into the current regcache. */
1120 get_current_regcache ()->restore (scratch
.get ());
1122 /* We've made right mess of GDB's local state, just discard
1124 reinit_frame_cache ();
1128 frame_register_unwind (frame_info
*next_frame
, int regnum
,
1129 int *optimizedp
, int *unavailablep
,
1130 enum lval_type
*lvalp
, CORE_ADDR
*addrp
,
1131 int *realnump
, gdb_byte
*bufferp
)
1133 struct value
*value
;
1135 /* Require all but BUFFERP to be valid. A NULL BUFFERP indicates
1136 that the value proper does not need to be fetched. */
1137 gdb_assert (optimizedp
!= NULL
);
1138 gdb_assert (lvalp
!= NULL
);
1139 gdb_assert (addrp
!= NULL
);
1140 gdb_assert (realnump
!= NULL
);
1141 /* gdb_assert (bufferp != NULL); */
1143 value
= frame_unwind_register_value (next_frame
, regnum
);
1145 gdb_assert (value
!= NULL
);
1147 *optimizedp
= value_optimized_out (value
);
1148 *unavailablep
= !value_entirely_available (value
);
1149 *lvalp
= VALUE_LVAL (value
);
1150 *addrp
= value_address (value
);
1151 if (*lvalp
== lval_register
)
1152 *realnump
= VALUE_REGNUM (value
);
1158 if (!*optimizedp
&& !*unavailablep
)
1159 memcpy (bufferp
, value_contents_all (value
),
1160 TYPE_LENGTH (value_type (value
)));
1162 memset (bufferp
, 0, TYPE_LENGTH (value_type (value
)));
1165 /* Dispose of the new value. This prevents watchpoints from
1166 trying to watch the saved frame pointer. */
1167 release_value (value
);
1171 frame_register (struct frame_info
*frame
, int regnum
,
1172 int *optimizedp
, int *unavailablep
, enum lval_type
*lvalp
,
1173 CORE_ADDR
*addrp
, int *realnump
, gdb_byte
*bufferp
)
1175 /* Require all but BUFFERP to be valid. A NULL BUFFERP indicates
1176 that the value proper does not need to be fetched. */
1177 gdb_assert (optimizedp
!= NULL
);
1178 gdb_assert (lvalp
!= NULL
);
1179 gdb_assert (addrp
!= NULL
);
1180 gdb_assert (realnump
!= NULL
);
1181 /* gdb_assert (bufferp != NULL); */
1183 /* Obtain the register value by unwinding the register from the next
1184 (more inner frame). */
1185 gdb_assert (frame
!= NULL
&& frame
->next
!= NULL
);
1186 frame_register_unwind (frame
->next
, regnum
, optimizedp
, unavailablep
,
1187 lvalp
, addrp
, realnump
, bufferp
);
1191 frame_unwind_register (frame_info
*next_frame
, int regnum
, gdb_byte
*buf
)
1197 enum lval_type lval
;
1199 frame_register_unwind (next_frame
, regnum
, &optimized
, &unavailable
,
1200 &lval
, &addr
, &realnum
, buf
);
1203 throw_error (OPTIMIZED_OUT_ERROR
,
1204 _("Register %d was not saved"), regnum
);
1206 throw_error (NOT_AVAILABLE_ERROR
,
1207 _("Register %d is not available"), regnum
);
1211 get_frame_register (struct frame_info
*frame
,
1212 int regnum
, gdb_byte
*buf
)
1214 frame_unwind_register (frame
->next
, regnum
, buf
);
1218 frame_unwind_register_value (frame_info
*next_frame
, int regnum
)
1220 FRAME_SCOPED_DEBUG_ENTER_EXIT
;
1222 gdb_assert (next_frame
!= NULL
);
1223 gdbarch
*gdbarch
= frame_unwind_arch (next_frame
);
1224 frame_debug_printf ("frame=%d, regnum=%d(%s)",
1225 next_frame
->level
, regnum
,
1226 user_reg_map_regnum_to_name (gdbarch
, regnum
));
1228 /* Find the unwinder. */
1229 if (next_frame
->unwind
== NULL
)
1230 frame_unwind_find_by_frame (next_frame
, &next_frame
->prologue_cache
);
1232 /* Ask this frame to unwind its register. */
1233 value
*value
= next_frame
->unwind
->prev_register (next_frame
,
1234 &next_frame
->prologue_cache
,
1239 string_file debug_file
;
1241 fprintf_unfiltered (&debug_file
, " ->");
1242 if (value_optimized_out (value
))
1244 fprintf_unfiltered (&debug_file
, " ");
1245 val_print_not_saved (&debug_file
);
1249 if (VALUE_LVAL (value
) == lval_register
)
1250 fprintf_unfiltered (&debug_file
, " register=%d",
1251 VALUE_REGNUM (value
));
1252 else if (VALUE_LVAL (value
) == lval_memory
)
1253 fprintf_unfiltered (&debug_file
, " address=%s",
1255 value_address (value
)));
1257 fprintf_unfiltered (&debug_file
, " computed");
1259 if (value_lazy (value
))
1260 fprintf_unfiltered (&debug_file
, " lazy");
1264 const gdb_byte
*buf
= value_contents (value
);
1266 fprintf_unfiltered (&debug_file
, " bytes=");
1267 fprintf_unfiltered (&debug_file
, "[");
1268 for (i
= 0; i
< register_size (gdbarch
, regnum
); i
++)
1269 fprintf_unfiltered (&debug_file
, "%02x", buf
[i
]);
1270 fprintf_unfiltered (&debug_file
, "]");
1274 frame_debug_printf ("%s", debug_file
.c_str ());
1281 get_frame_register_value (struct frame_info
*frame
, int regnum
)
1283 return frame_unwind_register_value (frame
->next
, regnum
);
1287 frame_unwind_register_signed (frame_info
*next_frame
, int regnum
)
1289 struct gdbarch
*gdbarch
= frame_unwind_arch (next_frame
);
1290 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
1291 int size
= register_size (gdbarch
, regnum
);
1292 struct value
*value
= frame_unwind_register_value (next_frame
, regnum
);
1294 gdb_assert (value
!= NULL
);
1296 if (value_optimized_out (value
))
1298 throw_error (OPTIMIZED_OUT_ERROR
,
1299 _("Register %d was not saved"), regnum
);
1301 if (!value_entirely_available (value
))
1303 throw_error (NOT_AVAILABLE_ERROR
,
1304 _("Register %d is not available"), regnum
);
1307 LONGEST r
= extract_signed_integer (value_contents_all (value
), size
,
1310 release_value (value
);
1315 get_frame_register_signed (struct frame_info
*frame
, int regnum
)
1317 return frame_unwind_register_signed (frame
->next
, regnum
);
1321 frame_unwind_register_unsigned (frame_info
*next_frame
, int regnum
)
1323 struct gdbarch
*gdbarch
= frame_unwind_arch (next_frame
);
1324 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
1325 int size
= register_size (gdbarch
, regnum
);
1326 struct value
*value
= frame_unwind_register_value (next_frame
, regnum
);
1328 gdb_assert (value
!= NULL
);
1330 if (value_optimized_out (value
))
1332 throw_error (OPTIMIZED_OUT_ERROR
,
1333 _("Register %d was not saved"), regnum
);
1335 if (!value_entirely_available (value
))
1337 throw_error (NOT_AVAILABLE_ERROR
,
1338 _("Register %d is not available"), regnum
);
1341 ULONGEST r
= extract_unsigned_integer (value_contents_all (value
), size
,
1344 release_value (value
);
1349 get_frame_register_unsigned (struct frame_info
*frame
, int regnum
)
1351 return frame_unwind_register_unsigned (frame
->next
, regnum
);
1355 read_frame_register_unsigned (frame_info
*frame
, int regnum
,
1358 struct value
*regval
= get_frame_register_value (frame
, regnum
);
1360 if (!value_optimized_out (regval
)
1361 && value_entirely_available (regval
))
1363 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
1364 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
1365 int size
= register_size (gdbarch
, VALUE_REGNUM (regval
));
1367 *val
= extract_unsigned_integer (value_contents (regval
), size
, byte_order
);
1375 put_frame_register (struct frame_info
*frame
, int regnum
,
1376 const gdb_byte
*buf
)
1378 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
1382 enum lval_type lval
;
1385 frame_register (frame
, regnum
, &optim
, &unavail
,
1386 &lval
, &addr
, &realnum
, NULL
);
1388 error (_("Attempt to assign to a register that was not saved."));
1393 write_memory (addr
, buf
, register_size (gdbarch
, regnum
));
1397 get_current_regcache ()->cooked_write (realnum
, buf
);
1400 error (_("Attempt to assign to an unmodifiable value."));
1404 /* This function is deprecated. Use get_frame_register_value instead,
1405 which provides more accurate information.
1407 Find and return the value of REGNUM for the specified stack frame.
1408 The number of bytes copied is REGISTER_SIZE (REGNUM).
1410 Returns 0 if the register value could not be found. */
1413 deprecated_frame_register_read (frame_info
*frame
, int regnum
,
1418 enum lval_type lval
;
1422 frame_register (frame
, regnum
, &optimized
, &unavailable
,
1423 &lval
, &addr
, &realnum
, myaddr
);
1425 return !optimized
&& !unavailable
;
1429 get_frame_register_bytes (frame_info
*frame
, int regnum
,
1431 gdb::array_view
<gdb_byte
> buffer
,
1432 int *optimizedp
, int *unavailablep
)
1434 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
1439 /* Skip registers wholly inside of OFFSET. */
1440 while (offset
>= register_size (gdbarch
, regnum
))
1442 offset
-= register_size (gdbarch
, regnum
);
1446 /* Ensure that we will not read beyond the end of the register file.
1447 This can only ever happen if the debug information is bad. */
1449 numregs
= gdbarch_num_cooked_regs (gdbarch
);
1450 for (i
= regnum
; i
< numregs
; i
++)
1452 int thissize
= register_size (gdbarch
, i
);
1455 break; /* This register is not available on this architecture. */
1456 maxsize
+= thissize
;
1459 int len
= buffer
.size ();
1461 error (_("Bad debug information detected: "
1462 "Attempt to read %d bytes from registers."), len
);
1464 /* Copy the data. */
1467 int curr_len
= register_size (gdbarch
, regnum
) - offset
;
1472 gdb_byte
*myaddr
= buffer
.data ();
1474 if (curr_len
== register_size (gdbarch
, regnum
))
1476 enum lval_type lval
;
1480 frame_register (frame
, regnum
, optimizedp
, unavailablep
,
1481 &lval
, &addr
, &realnum
, myaddr
);
1482 if (*optimizedp
|| *unavailablep
)
1487 struct value
*value
= frame_unwind_register_value (frame
->next
,
1489 gdb_assert (value
!= NULL
);
1490 *optimizedp
= value_optimized_out (value
);
1491 *unavailablep
= !value_entirely_available (value
);
1493 if (*optimizedp
|| *unavailablep
)
1495 release_value (value
);
1499 memcpy (myaddr
, value_contents_all (value
) + offset
, curr_len
);
1500 release_value (value
);
1516 put_frame_register_bytes (struct frame_info
*frame
, int regnum
,
1518 gdb::array_view
<const gdb_byte
> buffer
)
1520 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
1522 /* Skip registers wholly inside of OFFSET. */
1523 while (offset
>= register_size (gdbarch
, regnum
))
1525 offset
-= register_size (gdbarch
, regnum
);
1529 int len
= buffer
.size ();
1530 /* Copy the data. */
1533 int curr_len
= register_size (gdbarch
, regnum
) - offset
;
1538 const gdb_byte
*myaddr
= buffer
.data ();
1539 if (curr_len
== register_size (gdbarch
, regnum
))
1541 put_frame_register (frame
, regnum
, myaddr
);
1545 struct value
*value
= frame_unwind_register_value (frame
->next
,
1547 gdb_assert (value
!= NULL
);
1549 memcpy ((char *) value_contents_writeable (value
) + offset
, myaddr
,
1551 put_frame_register (frame
, regnum
, value_contents_raw (value
));
1552 release_value (value
);
1562 /* Create a sentinel frame. */
1564 static struct frame_info
*
1565 create_sentinel_frame (struct program_space
*pspace
, struct regcache
*regcache
)
1567 struct frame_info
*frame
= FRAME_OBSTACK_ZALLOC (struct frame_info
);
1570 frame
->pspace
= pspace
;
1571 frame
->aspace
= regcache
->aspace ();
1572 /* Explicitly initialize the sentinel frame's cache. Provide it
1573 with the underlying regcache. In the future additional
1574 information, such as the frame's thread will be added. */
1575 frame
->prologue_cache
= sentinel_frame_cache (regcache
);
1576 /* For the moment there is only one sentinel frame implementation. */
1577 frame
->unwind
= &sentinel_frame_unwind
;
1578 /* Link this frame back to itself. The frame is self referential
1579 (the unwound PC is the same as the pc), so make it so. */
1580 frame
->next
= frame
;
1581 /* The sentinel frame has a special ID. */
1582 frame
->this_id
.p
= frame_id_status::COMPUTED
;
1583 frame
->this_id
.value
= sentinel_frame_id
;
1585 frame_debug_printf (" -> %s", frame
->to_string ().c_str ());
1590 /* Cache for frame addresses already read by gdb. Valid only while
1591 inferior is stopped. Control variables for the frame cache should
1592 be local to this module. */
1594 static struct obstack frame_cache_obstack
;
1597 frame_obstack_zalloc (unsigned long size
)
1599 void *data
= obstack_alloc (&frame_cache_obstack
, size
);
1601 memset (data
, 0, size
);
1605 static struct frame_info
*get_prev_frame_always_1 (struct frame_info
*this_frame
);
1608 get_current_frame (void)
1610 struct frame_info
*current_frame
;
1612 /* First check, and report, the lack of registers. Having GDB
1613 report "No stack!" or "No memory" when the target doesn't even
1614 have registers is very confusing. Besides, "printcmd.exp"
1615 explicitly checks that ``print $pc'' with no registers prints "No
1617 if (!target_has_registers ())
1618 error (_("No registers."));
1619 if (!target_has_stack ())
1620 error (_("No stack."));
1621 if (!target_has_memory ())
1622 error (_("No memory."));
1623 /* Traceframes are effectively a substitute for the live inferior. */
1624 if (get_traceframe_number () < 0)
1625 validate_registers_access ();
1627 if (sentinel_frame
== NULL
)
1629 create_sentinel_frame (current_program_space
, get_current_regcache ());
1631 /* Set the current frame before computing the frame id, to avoid
1632 recursion inside compute_frame_id, in case the frame's
1633 unwinder decides to do a symbol lookup (which depends on the
1634 selected frame's block).
1636 This call must always succeed. In particular, nothing inside
1637 get_prev_frame_always_1 should try to unwind from the
1638 sentinel frame, because that could fail/throw, and we always
1639 want to leave with the current frame created and linked in --
1640 we should never end up with the sentinel frame as outermost
1642 current_frame
= get_prev_frame_always_1 (sentinel_frame
);
1643 gdb_assert (current_frame
!= NULL
);
1645 return current_frame
;
1648 /* The "selected" stack frame is used by default for local and arg
1651 The "single source of truth" for the selected frame is the
1652 SELECTED_FRAME_ID / SELECTED_FRAME_LEVEL pair.
1654 Frame IDs can be saved/restored across reinitializing the frame
1655 cache, while frame_info pointers can't (frame_info objects are
1656 invalidated). If we know the corresponding frame_info object, it
1657 is cached in SELECTED_FRAME.
1659 If SELECTED_FRAME_ID / SELECTED_FRAME_LEVEL are null_frame_id / -1,
1660 and the target has stack and is stopped, the selected frame is the
1661 current (innermost) frame. This means that SELECTED_FRAME_LEVEL is
1662 never 0 and SELECTED_FRAME_ID is never the ID of the innermost
1665 If SELECTED_FRAME_ID / SELECTED_FRAME_LEVEL are null_frame_id / -1,
1666 and the target has no stack or is executing, then there's no
1668 static frame_id selected_frame_id
= null_frame_id
;
1669 static int selected_frame_level
= -1;
1671 /* The cached frame_info object pointing to the selected frame.
1672 Looked up on demand by get_selected_frame. */
1673 static struct frame_info
*selected_frame
;
1678 save_selected_frame (frame_id
*frame_id
, int *frame_level
)
1681 *frame_id
= selected_frame_id
;
1682 *frame_level
= selected_frame_level
;
1688 restore_selected_frame (frame_id frame_id
, int frame_level
)
1691 /* save_selected_frame never returns level == 0, so we shouldn't see
1693 gdb_assert (frame_level
!= 0);
1695 /* FRAME_ID can be null_frame_id only IFF frame_level is -1. */
1696 gdb_assert ((frame_level
== -1 && !frame_id_p (frame_id
))
1697 || (frame_level
!= -1 && frame_id_p (frame_id
)));
1699 selected_frame_id
= frame_id
;
1700 selected_frame_level
= frame_level
;
1702 /* Will be looked up later by get_selected_frame. */
1703 selected_frame
= nullptr;
1709 lookup_selected_frame (struct frame_id a_frame_id
, int frame_level
)
1711 struct frame_info
*frame
= NULL
;
1714 /* This either means there was no selected frame, or the selected
1715 frame was the current frame. In either case, select the current
1717 if (frame_level
== -1)
1719 select_frame (get_current_frame ());
1723 /* select_frame never saves 0 in SELECTED_FRAME_LEVEL, so we
1724 shouldn't see it here. */
1725 gdb_assert (frame_level
> 0);
1727 /* Restore by level first, check if the frame id is the same as
1728 expected. If that fails, try restoring by frame id. If that
1729 fails, nothing to do, just warn the user. */
1731 count
= frame_level
;
1732 frame
= find_relative_frame (get_current_frame (), &count
);
1735 /* The frame ids must match - either both valid or both
1736 outer_frame_id. The latter case is not failsafe, but since
1737 it's highly unlikely the search by level finds the wrong
1738 frame, it's 99.9(9)% of the time (for all practical purposes)
1740 && frame_id_eq (get_frame_id (frame
), a_frame_id
))
1742 /* Cool, all is fine. */
1743 select_frame (frame
);
1747 frame
= frame_find_by_id (a_frame_id
);
1750 /* Cool, refound it. */
1751 select_frame (frame
);
1755 /* Nothing else to do, the frame layout really changed. Select the
1756 innermost stack frame. */
1757 select_frame (get_current_frame ());
1759 /* Warn the user. */
1760 if (frame_level
> 0 && !current_uiout
->is_mi_like_p ())
1762 warning (_("Couldn't restore frame #%d in "
1763 "current thread. Bottom (innermost) frame selected:"),
1765 /* For MI, we should probably have a notification about current
1766 frame change. But this error is not very likely, so don't
1768 print_stack_frame (get_selected_frame (NULL
), 1, SRC_AND_LOC
, 1);
1775 if (!target_has_registers () || !target_has_stack ()
1776 || !target_has_memory ())
1779 /* Traceframes are effectively a substitute for the live inferior. */
1780 if (get_traceframe_number () < 0)
1782 /* No current inferior, no frame. */
1783 if (inferior_ptid
== null_ptid
)
1786 thread_info
*tp
= inferior_thread ();
1787 /* Don't try to read from a dead thread. */
1788 if (tp
->state
== THREAD_EXITED
)
1791 /* ... or from a spinning thread. */
1802 get_selected_frame (const char *message
)
1804 if (selected_frame
== NULL
)
1806 if (message
!= NULL
&& !has_stack_frames ())
1807 error (("%s"), message
);
1809 lookup_selected_frame (selected_frame_id
, selected_frame_level
);
1811 /* There is always a frame. */
1812 gdb_assert (selected_frame
!= NULL
);
1813 return selected_frame
;
1816 /* This is a variant of get_selected_frame() which can be called when
1817 the inferior does not have a frame; in that case it will return
1818 NULL instead of calling error(). */
1821 deprecated_safe_get_selected_frame (void)
1823 if (!has_stack_frames ())
1825 return get_selected_frame (NULL
);
1828 /* Select frame FI (or NULL - to invalidate the selected frame). */
1831 select_frame (struct frame_info
*fi
)
1833 selected_frame
= fi
;
1834 selected_frame_level
= frame_relative_level (fi
);
1835 if (selected_frame_level
== 0)
1837 /* Treat the current frame especially -- we want to always
1838 save/restore it without warning, even if the frame ID changes
1839 (see lookup_selected_frame). E.g.:
1841 // The current frame is selected, the target had just stopped.
1843 scoped_restore_selected_frame restore_frame;
1844 some_operation_that_changes_the_stack ();
1846 // scoped_restore_selected_frame's dtor runs, but the
1847 // original frame_id can't be found. No matter whether it
1848 // is found or not, we still end up with the now-current
1849 // frame selected. Warning in lookup_selected_frame in this
1850 // case seems pointless.
1852 Also get_frame_id may access the target's registers/memory,
1853 and thus skipping get_frame_id optimizes the common case.
1855 Saving the selected frame this way makes get_selected_frame
1856 and restore_current_frame return/re-select whatever frame is
1857 the innermost (current) then. */
1858 selected_frame_level
= -1;
1859 selected_frame_id
= null_frame_id
;
1862 selected_frame_id
= get_frame_id (fi
);
1864 /* NOTE: cagney/2002-05-04: FI can be NULL. This occurs when the
1865 frame is being invalidated. */
1867 /* FIXME: kseitz/2002-08-28: It would be nice to call
1868 selected_frame_level_changed_event() right here, but due to limitations
1869 in the current interfaces, we would end up flooding UIs with events
1870 because select_frame() is used extensively internally.
1872 Once we have frame-parameterized frame (and frame-related) commands,
1873 the event notification can be moved here, since this function will only
1874 be called when the user's selected frame is being changed. */
1876 /* Ensure that symbols for this frame are read in. Also, determine the
1877 source language of this frame, and switch to it if desired. */
1882 /* We retrieve the frame's symtab by using the frame PC.
1883 However we cannot use the frame PC as-is, because it usually
1884 points to the instruction following the "call", which is
1885 sometimes the first instruction of another function. So we
1886 rely on get_frame_address_in_block() which provides us with a
1887 PC which is guaranteed to be inside the frame's code
1889 if (get_frame_address_in_block_if_available (fi
, &pc
))
1891 struct compunit_symtab
*cust
= find_pc_compunit_symtab (pc
);
1894 && compunit_language (cust
) != current_language
->la_language
1895 && compunit_language (cust
) != language_unknown
1896 && language_mode
== language_mode_auto
)
1897 set_language (compunit_language (cust
));
1902 /* Create an arbitrary (i.e. address specified by user) or innermost frame.
1903 Always returns a non-NULL value. */
1906 create_new_frame (CORE_ADDR addr
, CORE_ADDR pc
)
1908 struct frame_info
*fi
;
1910 frame_debug_printf ("addr=%s, pc=%s", hex_string (addr
), hex_string (pc
));
1912 fi
= FRAME_OBSTACK_ZALLOC (struct frame_info
);
1914 fi
->next
= create_sentinel_frame (current_program_space
,
1915 get_current_regcache ());
1917 /* Set/update this frame's cached PC value, found in the next frame.
1918 Do this before looking for this frame's unwinder. A sniffer is
1919 very likely to read this, and the corresponding unwinder is
1920 entitled to rely that the PC doesn't magically change. */
1921 fi
->next
->prev_pc
.value
= pc
;
1922 fi
->next
->prev_pc
.status
= CC_VALUE
;
1924 /* We currently assume that frame chain's can't cross spaces. */
1925 fi
->pspace
= fi
->next
->pspace
;
1926 fi
->aspace
= fi
->next
->aspace
;
1928 /* Select/initialize both the unwind function and the frame's type
1930 frame_unwind_find_by_frame (fi
, &fi
->prologue_cache
);
1932 fi
->this_id
.p
= frame_id_status::COMPUTED
;
1933 fi
->this_id
.value
= frame_id_build (addr
, pc
);
1935 frame_debug_printf (" -> %s", fi
->to_string ().c_str ());
1940 /* Return the frame that THIS_FRAME calls (NULL if THIS_FRAME is the
1941 innermost frame). Be careful to not fall off the bottom of the
1942 frame chain and onto the sentinel frame. */
1945 get_next_frame (struct frame_info
*this_frame
)
1947 if (this_frame
->level
> 0)
1948 return this_frame
->next
;
1953 /* Return the frame that THIS_FRAME calls. If THIS_FRAME is the
1954 innermost (i.e. current) frame, return the sentinel frame. Thus,
1955 unlike get_next_frame(), NULL will never be returned. */
1958 get_next_frame_sentinel_okay (struct frame_info
*this_frame
)
1960 gdb_assert (this_frame
!= NULL
);
1962 /* Note that, due to the manner in which the sentinel frame is
1963 constructed, this_frame->next still works even when this_frame
1964 is the sentinel frame. But we disallow it here anyway because
1965 calling get_next_frame_sentinel_okay() on the sentinel frame
1966 is likely a coding error. */
1967 gdb_assert (this_frame
!= sentinel_frame
);
1969 return this_frame
->next
;
1972 /* Observer for the target_changed event. */
1975 frame_observer_target_changed (struct target_ops
*target
)
1977 reinit_frame_cache ();
1980 /* Flush the entire frame cache. */
1983 reinit_frame_cache (void)
1985 struct frame_info
*fi
;
1987 ++frame_cache_generation
;
1989 /* Tear down all frame caches. */
1990 for (fi
= sentinel_frame
; fi
!= NULL
; fi
= fi
->prev
)
1992 if (fi
->prologue_cache
&& fi
->unwind
->dealloc_cache
)
1993 fi
->unwind
->dealloc_cache (fi
, fi
->prologue_cache
);
1994 if (fi
->base_cache
&& fi
->base
->unwind
->dealloc_cache
)
1995 fi
->base
->unwind
->dealloc_cache (fi
, fi
->base_cache
);
1998 /* Since we can't really be sure what the first object allocated was. */
1999 obstack_free (&frame_cache_obstack
, 0);
2000 obstack_init (&frame_cache_obstack
);
2002 if (sentinel_frame
!= NULL
)
2003 annotate_frames_invalid ();
2005 sentinel_frame
= NULL
; /* Invalidate cache */
2006 select_frame (NULL
);
2007 frame_stash_invalidate ();
2009 frame_debug_printf ("generation=%d", frame_cache_generation
);
2012 /* Find where a register is saved (in memory or another register).
2013 The result of frame_register_unwind is just where it is saved
2014 relative to this particular frame. */
2017 frame_register_unwind_location (struct frame_info
*this_frame
, int regnum
,
2018 int *optimizedp
, enum lval_type
*lvalp
,
2019 CORE_ADDR
*addrp
, int *realnump
)
2021 gdb_assert (this_frame
== NULL
|| this_frame
->level
>= 0);
2023 while (this_frame
!= NULL
)
2027 frame_register_unwind (this_frame
, regnum
, optimizedp
, &unavailable
,
2028 lvalp
, addrp
, realnump
, NULL
);
2033 if (*lvalp
!= lval_register
)
2037 this_frame
= get_next_frame (this_frame
);
2041 /* Get the previous raw frame, and check that it is not identical to
2042 same other frame frame already in the chain. If it is, there is
2043 most likely a stack cycle, so we discard it, and mark THIS_FRAME as
2044 outermost, with UNWIND_SAME_ID stop reason. Unlike the other
2045 validity tests, that compare THIS_FRAME and the next frame, we do
2046 this right after creating the previous frame, to avoid ever ending
2047 up with two frames with the same id in the frame chain. */
2049 static struct frame_info
*
2050 get_prev_frame_if_no_cycle (struct frame_info
*this_frame
)
2052 struct frame_info
*prev_frame
;
2054 prev_frame
= get_prev_frame_raw (this_frame
);
2056 /* Don't compute the frame id of the current frame yet. Unwinding
2057 the sentinel frame can fail (e.g., if the thread is gone and we
2058 can't thus read its registers). If we let the cycle detection
2059 code below try to compute a frame ID, then an error thrown from
2060 within the frame ID computation would result in the sentinel
2061 frame as outermost frame, which is bogus. Instead, we'll compute
2062 the current frame's ID lazily in get_frame_id. Note that there's
2063 no point in doing cycle detection when there's only one frame, so
2064 nothing is lost here. */
2065 if (prev_frame
->level
== 0)
2068 unsigned int entry_generation
= get_frame_cache_generation ();
2072 compute_frame_id (prev_frame
);
2073 if (!frame_stash_add (prev_frame
))
2075 /* Another frame with the same id was already in the stash. We just
2076 detected a cycle. */
2077 frame_debug_printf (" -> nullptr // this frame has same ID");
2079 this_frame
->stop_reason
= UNWIND_SAME_ID
;
2081 prev_frame
->next
= NULL
;
2082 this_frame
->prev
= NULL
;
2086 catch (const gdb_exception
&ex
)
2088 if (get_frame_cache_generation () == entry_generation
)
2090 prev_frame
->next
= NULL
;
2091 this_frame
->prev
= NULL
;
2100 /* Helper function for get_prev_frame_always, this is called inside a
2101 TRY_CATCH block. Return the frame that called THIS_FRAME or NULL if
2102 there is no such frame. This may throw an exception. */
2104 static struct frame_info
*
2105 get_prev_frame_always_1 (struct frame_info
*this_frame
)
2107 FRAME_SCOPED_DEBUG_ENTER_EXIT
;
2109 gdb_assert (this_frame
!= NULL
);
2113 if (this_frame
!= NULL
)
2114 frame_debug_printf ("this_frame=%d", this_frame
->level
);
2116 frame_debug_printf ("this_frame=nullptr");
2119 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
2121 /* Only try to do the unwind once. */
2122 if (this_frame
->prev_p
)
2124 frame_debug_printf (" -> %s // cached",
2125 this_frame
->prev
->to_string ().c_str ());
2126 return this_frame
->prev
;
2129 /* If the frame unwinder hasn't been selected yet, we must do so
2130 before setting prev_p; otherwise the check for misbehaved
2131 sniffers will think that this frame's sniffer tried to unwind
2132 further (see frame_cleanup_after_sniffer). */
2133 if (this_frame
->unwind
== NULL
)
2134 frame_unwind_find_by_frame (this_frame
, &this_frame
->prologue_cache
);
2136 this_frame
->prev_p
= true;
2137 this_frame
->stop_reason
= UNWIND_NO_REASON
;
2139 /* If we are unwinding from an inline frame, all of the below tests
2140 were already performed when we unwound from the next non-inline
2141 frame. We must skip them, since we can not get THIS_FRAME's ID
2142 until we have unwound all the way down to the previous non-inline
2144 if (get_frame_type (this_frame
) == INLINE_FRAME
)
2145 return get_prev_frame_if_no_cycle (this_frame
);
2147 /* If this_frame is the current frame, then compute and stash its
2148 frame id prior to fetching and computing the frame id of the
2149 previous frame. Otherwise, the cycle detection code in
2150 get_prev_frame_if_no_cycle() will not work correctly. When
2151 get_frame_id() is called later on, an assertion error will be
2152 triggered in the event of a cycle between the current frame and
2155 Note we do this after the INLINE_FRAME check above. That is
2156 because the inline frame's frame id computation needs to fetch
2157 the frame id of its previous real stack frame. I.e., we need to
2158 avoid recursion in that case. This is OK since we're sure the
2159 inline frame won't create a cycle with the real stack frame. See
2160 inline_frame_this_id. */
2161 if (this_frame
->level
== 0)
2162 get_frame_id (this_frame
);
2164 /* Check that this frame is unwindable. If it isn't, don't try to
2165 unwind to the prev frame. */
2166 this_frame
->stop_reason
2167 = this_frame
->unwind
->stop_reason (this_frame
,
2168 &this_frame
->prologue_cache
);
2170 if (this_frame
->stop_reason
!= UNWIND_NO_REASON
)
2173 (" -> nullptr // %s",
2174 frame_stop_reason_symbol_string (this_frame
->stop_reason
));
2178 /* Check that this frame's ID isn't inner to (younger, below, next)
2179 the next frame. This happens when a frame unwind goes backwards.
2180 This check is valid only if this frame and the next frame are NORMAL.
2181 See the comment at frame_id_inner for details. */
2182 if (get_frame_type (this_frame
) == NORMAL_FRAME
2183 && this_frame
->next
->unwind
->type
== NORMAL_FRAME
2184 && frame_id_inner (get_frame_arch (this_frame
->next
),
2185 get_frame_id (this_frame
),
2186 get_frame_id (this_frame
->next
)))
2188 CORE_ADDR this_pc_in_block
;
2189 struct minimal_symbol
*morestack_msym
;
2190 const char *morestack_name
= NULL
;
2192 /* gcc -fsplit-stack __morestack can continue the stack anywhere. */
2193 this_pc_in_block
= get_frame_address_in_block (this_frame
);
2194 morestack_msym
= lookup_minimal_symbol_by_pc (this_pc_in_block
).minsym
;
2196 morestack_name
= morestack_msym
->linkage_name ();
2197 if (!morestack_name
|| strcmp (morestack_name
, "__morestack") != 0)
2199 frame_debug_printf (" -> nullptr // this frame ID is inner");
2200 this_frame
->stop_reason
= UNWIND_INNER_ID
;
2205 /* Check that this and the next frame do not unwind the PC register
2206 to the same memory location. If they do, then even though they
2207 have different frame IDs, the new frame will be bogus; two
2208 functions can't share a register save slot for the PC. This can
2209 happen when the prologue analyzer finds a stack adjustment, but
2212 This check does assume that the "PC register" is roughly a
2213 traditional PC, even if the gdbarch_unwind_pc method adjusts
2214 it (we do not rely on the value, only on the unwound PC being
2215 dependent on this value). A potential improvement would be
2216 to have the frame prev_pc method and the gdbarch unwind_pc
2217 method set the same lval and location information as
2218 frame_register_unwind. */
2219 if (this_frame
->level
> 0
2220 && gdbarch_pc_regnum (gdbarch
) >= 0
2221 && get_frame_type (this_frame
) == NORMAL_FRAME
2222 && (get_frame_type (this_frame
->next
) == NORMAL_FRAME
2223 || get_frame_type (this_frame
->next
) == INLINE_FRAME
))
2225 int optimized
, realnum
, nrealnum
;
2226 enum lval_type lval
, nlval
;
2227 CORE_ADDR addr
, naddr
;
2229 frame_register_unwind_location (this_frame
,
2230 gdbarch_pc_regnum (gdbarch
),
2231 &optimized
, &lval
, &addr
, &realnum
);
2232 frame_register_unwind_location (get_next_frame (this_frame
),
2233 gdbarch_pc_regnum (gdbarch
),
2234 &optimized
, &nlval
, &naddr
, &nrealnum
);
2236 if ((lval
== lval_memory
&& lval
== nlval
&& addr
== naddr
)
2237 || (lval
== lval_register
&& lval
== nlval
&& realnum
== nrealnum
))
2239 frame_debug_printf (" -> nullptr // no saved PC");
2240 this_frame
->stop_reason
= UNWIND_NO_SAVED_PC
;
2241 this_frame
->prev
= NULL
;
2246 return get_prev_frame_if_no_cycle (this_frame
);
2249 /* Return a "struct frame_info" corresponding to the frame that called
2250 THIS_FRAME. Returns NULL if there is no such frame.
2252 Unlike get_prev_frame, this function always tries to unwind the
2256 get_prev_frame_always (struct frame_info
*this_frame
)
2258 struct frame_info
*prev_frame
= NULL
;
2262 prev_frame
= get_prev_frame_always_1 (this_frame
);
2264 catch (const gdb_exception_error
&ex
)
2266 if (ex
.error
== MEMORY_ERROR
)
2268 this_frame
->stop_reason
= UNWIND_MEMORY_ERROR
;
2269 if (ex
.message
!= NULL
)
2274 /* The error needs to live as long as the frame does.
2275 Allocate using stack local STOP_STRING then assign the
2276 pointer to the frame, this allows the STOP_STRING on the
2277 frame to be of type 'const char *'. */
2278 size
= ex
.message
->size () + 1;
2279 stop_string
= (char *) frame_obstack_zalloc (size
);
2280 memcpy (stop_string
, ex
.what (), size
);
2281 this_frame
->stop_string
= stop_string
;
2292 /* Construct a new "struct frame_info" and link it previous to
2295 static struct frame_info
*
2296 get_prev_frame_raw (struct frame_info
*this_frame
)
2298 struct frame_info
*prev_frame
;
2300 /* Allocate the new frame but do not wire it in to the frame chain.
2301 Some (bad) code in INIT_FRAME_EXTRA_INFO tries to look along
2302 frame->next to pull some fancy tricks (of course such code is, by
2303 definition, recursive). Try to prevent it.
2305 There is no reason to worry about memory leaks, should the
2306 remainder of the function fail. The allocated memory will be
2307 quickly reclaimed when the frame cache is flushed, and the `we've
2308 been here before' check above will stop repeated memory
2309 allocation calls. */
2310 prev_frame
= FRAME_OBSTACK_ZALLOC (struct frame_info
);
2311 prev_frame
->level
= this_frame
->level
+ 1;
2313 /* For now, assume we don't have frame chains crossing address
2315 prev_frame
->pspace
= this_frame
->pspace
;
2316 prev_frame
->aspace
= this_frame
->aspace
;
2318 /* Don't yet compute ->unwind (and hence ->type). It is computed
2319 on-demand in get_frame_type, frame_register_unwind, and
2322 /* Don't yet compute the frame's ID. It is computed on-demand by
2325 /* The unwound frame ID is validate at the start of this function,
2326 as part of the logic to decide if that frame should be further
2327 unwound, and not here while the prev frame is being created.
2328 Doing this makes it possible for the user to examine a frame that
2329 has an invalid frame ID.
2331 Some very old VAX code noted: [...] For the sake of argument,
2332 suppose that the stack is somewhat trashed (which is one reason
2333 that "info frame" exists). So, return 0 (indicating we don't
2334 know the address of the arglist) if we don't know what frame this
2338 this_frame
->prev
= prev_frame
;
2339 prev_frame
->next
= this_frame
;
2341 frame_debug_printf (" -> %s", prev_frame
->to_string ().c_str ());
2346 /* Debug routine to print a NULL frame being returned. */
2349 frame_debug_got_null_frame (struct frame_info
*this_frame
,
2354 if (this_frame
!= NULL
)
2355 frame_debug_printf ("this_frame=%d -> %s", this_frame
->level
, reason
);
2357 frame_debug_printf ("this_frame=nullptr -> %s", reason
);
2361 /* Is this (non-sentinel) frame in the "main"() function? */
2364 inside_main_func (frame_info
*this_frame
)
2366 if (current_program_space
->symfile_object_file
== nullptr)
2370 const char *name
= main_name ();
2371 bound_minimal_symbol msymbol
2372 = lookup_minimal_symbol (name
, NULL
,
2373 current_program_space
->symfile_object_file
);
2374 if (msymbol
.minsym
== nullptr)
2376 /* In some language (for example Fortran) there will be no minimal
2377 symbol with the name of the main function. In this case we should
2378 search the full symbols to see if we can find a match. */
2379 struct block_symbol bs
= lookup_symbol (name
, NULL
, VAR_DOMAIN
, 0);
2380 if (bs
.symbol
== nullptr)
2383 const struct block
*block
= SYMBOL_BLOCK_VALUE (bs
.symbol
);
2384 gdb_assert (block
!= nullptr);
2385 sym_addr
= BLOCK_START (block
);
2388 sym_addr
= BMSYMBOL_VALUE_ADDRESS (msymbol
);
2390 /* Convert any function descriptor addresses into the actual function
2392 sym_addr
= gdbarch_convert_from_func_ptr_addr
2393 (get_frame_arch (this_frame
), sym_addr
, current_inferior ()->top_target ());
2395 return sym_addr
== get_frame_func (this_frame
);
2398 /* Test whether THIS_FRAME is inside the process entry point function. */
2401 inside_entry_func (frame_info
*this_frame
)
2403 CORE_ADDR entry_point
;
2405 if (!entry_point_address_query (&entry_point
))
2408 return get_frame_func (this_frame
) == entry_point
;
2411 /* Return a structure containing various interesting information about
2412 the frame that called THIS_FRAME. Returns NULL if there is entier
2413 no such frame or the frame fails any of a set of target-independent
2414 condition that should terminate the frame chain (e.g., as unwinding
2417 This function should not contain target-dependent tests, such as
2418 checking whether the program-counter is zero. */
2421 get_prev_frame (struct frame_info
*this_frame
)
2423 FRAME_SCOPED_DEBUG_ENTER_EXIT
;
2428 /* There is always a frame. If this assertion fails, suspect that
2429 something should be calling get_selected_frame() or
2430 get_current_frame(). */
2431 gdb_assert (this_frame
!= NULL
);
2433 frame_pc_p
= get_frame_pc_if_available (this_frame
, &frame_pc
);
2435 /* tausq/2004-12-07: Dummy frames are skipped because it doesn't make much
2436 sense to stop unwinding at a dummy frame. One place where a dummy
2437 frame may have an address "inside_main_func" is on HPUX. On HPUX, the
2438 pcsqh register (space register for the instruction at the head of the
2439 instruction queue) cannot be written directly; the only way to set it
2440 is to branch to code that is in the target space. In order to implement
2441 frame dummies on HPUX, the called function is made to jump back to where
2442 the inferior was when the user function was called. If gdb was inside
2443 the main function when we created the dummy frame, the dummy frame will
2444 point inside the main function. */
2445 if (this_frame
->level
>= 0
2446 && get_frame_type (this_frame
) == NORMAL_FRAME
2447 && !user_set_backtrace_options
.backtrace_past_main
2449 && inside_main_func (this_frame
))
2450 /* Don't unwind past main(). Note, this is done _before_ the
2451 frame has been marked as previously unwound. That way if the
2452 user later decides to enable unwinds past main(), that will
2453 automatically happen. */
2455 frame_debug_got_null_frame (this_frame
, "inside main func");
2459 /* If the user's backtrace limit has been exceeded, stop. We must
2460 add two to the current level; one of those accounts for backtrace_limit
2461 being 1-based and the level being 0-based, and the other accounts for
2462 the level of the new frame instead of the level of the current
2464 if (this_frame
->level
+ 2 > user_set_backtrace_options
.backtrace_limit
)
2466 frame_debug_got_null_frame (this_frame
, "backtrace limit exceeded");
2470 /* If we're already inside the entry function for the main objfile,
2471 then it isn't valid. Don't apply this test to a dummy frame -
2472 dummy frame PCs typically land in the entry func. Don't apply
2473 this test to the sentinel frame. Sentinel frames should always
2474 be allowed to unwind. */
2475 /* NOTE: cagney/2003-07-07: Fixed a bug in inside_main_func() -
2476 wasn't checking for "main" in the minimal symbols. With that
2477 fixed asm-source tests now stop in "main" instead of halting the
2478 backtrace in weird and wonderful ways somewhere inside the entry
2479 file. Suspect that tests for inside the entry file/func were
2480 added to work around that (now fixed) case. */
2481 /* NOTE: cagney/2003-07-15: danielj (if I'm reading it right)
2482 suggested having the inside_entry_func test use the
2483 inside_main_func() msymbol trick (along with entry_point_address()
2484 I guess) to determine the address range of the start function.
2485 That should provide a far better stopper than the current
2487 /* NOTE: tausq/2004-10-09: this is needed if, for example, the compiler
2488 applied tail-call optimizations to main so that a function called
2489 from main returns directly to the caller of main. Since we don't
2490 stop at main, we should at least stop at the entry point of the
2492 if (this_frame
->level
>= 0
2493 && get_frame_type (this_frame
) == NORMAL_FRAME
2494 && !user_set_backtrace_options
.backtrace_past_entry
2496 && inside_entry_func (this_frame
))
2498 frame_debug_got_null_frame (this_frame
, "inside entry func");
2502 /* Assume that the only way to get a zero PC is through something
2503 like a SIGSEGV or a dummy frame, and hence that NORMAL frames
2504 will never unwind a zero PC. */
2505 if (this_frame
->level
> 0
2506 && (get_frame_type (this_frame
) == NORMAL_FRAME
2507 || get_frame_type (this_frame
) == INLINE_FRAME
)
2508 && get_frame_type (get_next_frame (this_frame
)) == NORMAL_FRAME
2509 && frame_pc_p
&& frame_pc
== 0)
2511 frame_debug_got_null_frame (this_frame
, "zero PC");
2515 return get_prev_frame_always (this_frame
);
2519 get_prev_frame_id_by_id (struct frame_id id
)
2521 struct frame_id prev_id
;
2522 struct frame_info
*frame
;
2524 frame
= frame_find_by_id (id
);
2527 prev_id
= get_frame_id (get_prev_frame (frame
));
2529 prev_id
= null_frame_id
;
2535 get_frame_pc (struct frame_info
*frame
)
2537 gdb_assert (frame
->next
!= NULL
);
2538 return frame_unwind_pc (frame
->next
);
2542 get_frame_pc_if_available (frame_info
*frame
, CORE_ADDR
*pc
)
2545 gdb_assert (frame
->next
!= NULL
);
2549 *pc
= frame_unwind_pc (frame
->next
);
2551 catch (const gdb_exception_error
&ex
)
2553 if (ex
.error
== NOT_AVAILABLE_ERROR
)
2562 /* Return an address that falls within THIS_FRAME's code block. */
2565 get_frame_address_in_block (struct frame_info
*this_frame
)
2567 /* A draft address. */
2568 CORE_ADDR pc
= get_frame_pc (this_frame
);
2570 struct frame_info
*next_frame
= this_frame
->next
;
2572 /* Calling get_frame_pc returns the resume address for THIS_FRAME.
2573 Normally the resume address is inside the body of the function
2574 associated with THIS_FRAME, but there is a special case: when
2575 calling a function which the compiler knows will never return
2576 (for instance abort), the call may be the very last instruction
2577 in the calling function. The resume address will point after the
2578 call and may be at the beginning of a different function
2581 If THIS_FRAME is a signal frame or dummy frame, then we should
2582 not adjust the unwound PC. For a dummy frame, GDB pushed the
2583 resume address manually onto the stack. For a signal frame, the
2584 OS may have pushed the resume address manually and invoked the
2585 handler (e.g. GNU/Linux), or invoked the trampoline which called
2586 the signal handler - but in either case the signal handler is
2587 expected to return to the trampoline. So in both of these
2588 cases we know that the resume address is executable and
2589 related. So we only need to adjust the PC if THIS_FRAME
2590 is a normal function.
2592 If the program has been interrupted while THIS_FRAME is current,
2593 then clearly the resume address is inside the associated
2594 function. There are three kinds of interruption: debugger stop
2595 (next frame will be SENTINEL_FRAME), operating system
2596 signal or exception (next frame will be SIGTRAMP_FRAME),
2597 or debugger-induced function call (next frame will be
2598 DUMMY_FRAME). So we only need to adjust the PC if
2599 NEXT_FRAME is a normal function.
2601 We check the type of NEXT_FRAME first, since it is already
2602 known; frame type is determined by the unwinder, and since
2603 we have THIS_FRAME we've already selected an unwinder for
2606 If the next frame is inlined, we need to keep going until we find
2607 the real function - for instance, if a signal handler is invoked
2608 while in an inlined function, then the code address of the
2609 "calling" normal function should not be adjusted either. */
2611 while (get_frame_type (next_frame
) == INLINE_FRAME
)
2612 next_frame
= next_frame
->next
;
2614 if ((get_frame_type (next_frame
) == NORMAL_FRAME
2615 || get_frame_type (next_frame
) == TAILCALL_FRAME
)
2616 && (get_frame_type (this_frame
) == NORMAL_FRAME
2617 || get_frame_type (this_frame
) == TAILCALL_FRAME
2618 || get_frame_type (this_frame
) == INLINE_FRAME
))
2625 get_frame_address_in_block_if_available (frame_info
*this_frame
,
2631 *pc
= get_frame_address_in_block (this_frame
);
2633 catch (const gdb_exception_error
&ex
)
2635 if (ex
.error
== NOT_AVAILABLE_ERROR
)
2644 find_frame_sal (frame_info
*frame
)
2646 struct frame_info
*next_frame
;
2650 if (frame_inlined_callees (frame
) > 0)
2654 /* If the current frame has some inlined callees, and we have a next
2655 frame, then that frame must be an inlined frame. In this case
2656 this frame's sal is the "call site" of the next frame's inlined
2657 function, which can not be inferred from get_frame_pc. */
2658 next_frame
= get_next_frame (frame
);
2660 sym
= get_frame_function (next_frame
);
2662 sym
= inline_skipped_symbol (inferior_thread ());
2664 /* If frame is inline, it certainly has symbols. */
2667 symtab_and_line sal
;
2668 if (SYMBOL_LINE (sym
) != 0)
2670 sal
.symtab
= symbol_symtab (sym
);
2671 sal
.line
= SYMBOL_LINE (sym
);
2674 /* If the symbol does not have a location, we don't know where
2675 the call site is. Do not pretend to. This is jarring, but
2676 we can't do much better. */
2677 sal
.pc
= get_frame_pc (frame
);
2679 sal
.pspace
= get_frame_program_space (frame
);
2683 /* If FRAME is not the innermost frame, that normally means that
2684 FRAME->pc points at the return instruction (which is *after* the
2685 call instruction), and we want to get the line containing the
2686 call (because the call is where the user thinks the program is).
2687 However, if the next frame is either a SIGTRAMP_FRAME or a
2688 DUMMY_FRAME, then the next frame will contain a saved interrupt
2689 PC and such a PC indicates the current (rather than next)
2690 instruction/line, consequently, for such cases, want to get the
2691 line containing fi->pc. */
2692 if (!get_frame_pc_if_available (frame
, &pc
))
2695 notcurrent
= (pc
!= get_frame_address_in_block (frame
));
2696 return find_pc_line (pc
, notcurrent
);
2699 /* Per "frame.h", return the ``address'' of the frame. Code should
2700 really be using get_frame_id(). */
2702 get_frame_base (struct frame_info
*fi
)
2704 return get_frame_id (fi
).stack_addr
;
2707 /* High-level offsets into the frame. Used by the debug info. */
2710 get_frame_base_address (struct frame_info
*fi
)
2712 if (get_frame_type (fi
) != NORMAL_FRAME
)
2714 if (fi
->base
== NULL
)
2715 fi
->base
= frame_base_find_by_frame (fi
);
2716 /* Sneaky: If the low-level unwind and high-level base code share a
2717 common unwinder, let them share the prologue cache. */
2718 if (fi
->base
->unwind
== fi
->unwind
)
2719 return fi
->base
->this_base (fi
, &fi
->prologue_cache
);
2720 return fi
->base
->this_base (fi
, &fi
->base_cache
);
2724 get_frame_locals_address (struct frame_info
*fi
)
2726 if (get_frame_type (fi
) != NORMAL_FRAME
)
2728 /* If there isn't a frame address method, find it. */
2729 if (fi
->base
== NULL
)
2730 fi
->base
= frame_base_find_by_frame (fi
);
2731 /* Sneaky: If the low-level unwind and high-level base code share a
2732 common unwinder, let them share the prologue cache. */
2733 if (fi
->base
->unwind
== fi
->unwind
)
2734 return fi
->base
->this_locals (fi
, &fi
->prologue_cache
);
2735 return fi
->base
->this_locals (fi
, &fi
->base_cache
);
2739 get_frame_args_address (struct frame_info
*fi
)
2741 if (get_frame_type (fi
) != NORMAL_FRAME
)
2743 /* If there isn't a frame address method, find it. */
2744 if (fi
->base
== NULL
)
2745 fi
->base
= frame_base_find_by_frame (fi
);
2746 /* Sneaky: If the low-level unwind and high-level base code share a
2747 common unwinder, let them share the prologue cache. */
2748 if (fi
->base
->unwind
== fi
->unwind
)
2749 return fi
->base
->this_args (fi
, &fi
->prologue_cache
);
2750 return fi
->base
->this_args (fi
, &fi
->base_cache
);
2753 /* Return true if the frame unwinder for frame FI is UNWINDER; false
2757 frame_unwinder_is (frame_info
*fi
, const frame_unwind
*unwinder
)
2759 if (fi
->unwind
== nullptr)
2760 frame_unwind_find_by_frame (fi
, &fi
->prologue_cache
);
2762 return fi
->unwind
== unwinder
;
2765 /* Level of the selected frame: 0 for innermost, 1 for its caller, ...
2766 or -1 for a NULL frame. */
2769 frame_relative_level (struct frame_info
*fi
)
2778 get_frame_type (struct frame_info
*frame
)
2780 if (frame
->unwind
== NULL
)
2781 /* Initialize the frame's unwinder because that's what
2782 provides the frame's type. */
2783 frame_unwind_find_by_frame (frame
, &frame
->prologue_cache
);
2784 return frame
->unwind
->type
;
2787 struct program_space
*
2788 get_frame_program_space (struct frame_info
*frame
)
2790 return frame
->pspace
;
2793 struct program_space
*
2794 frame_unwind_program_space (struct frame_info
*this_frame
)
2796 gdb_assert (this_frame
);
2798 /* This is really a placeholder to keep the API consistent --- we
2799 assume for now that we don't have frame chains crossing
2801 return this_frame
->pspace
;
2804 const address_space
*
2805 get_frame_address_space (struct frame_info
*frame
)
2807 return frame
->aspace
;
2810 /* Memory access methods. */
2813 get_frame_memory (struct frame_info
*this_frame
, CORE_ADDR addr
,
2814 gdb::array_view
<gdb_byte
> buffer
)
2816 read_memory (addr
, buffer
.data (), buffer
.size ());
2820 get_frame_memory_signed (struct frame_info
*this_frame
, CORE_ADDR addr
,
2823 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
2824 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
2826 return read_memory_integer (addr
, len
, byte_order
);
2830 get_frame_memory_unsigned (struct frame_info
*this_frame
, CORE_ADDR addr
,
2833 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
2834 enum bfd_endian byte_order
= gdbarch_byte_order (gdbarch
);
2836 return read_memory_unsigned_integer (addr
, len
, byte_order
);
2840 safe_frame_unwind_memory (struct frame_info
*this_frame
,
2841 CORE_ADDR addr
, gdb::array_view
<gdb_byte
> buffer
)
2843 /* NOTE: target_read_memory returns zero on success! */
2844 return target_read_memory (addr
, buffer
.data (), buffer
.size ()) == 0;
2847 /* Architecture methods. */
2850 get_frame_arch (struct frame_info
*this_frame
)
2852 return frame_unwind_arch (this_frame
->next
);
2856 frame_unwind_arch (struct frame_info
*next_frame
)
2858 if (!next_frame
->prev_arch
.p
)
2860 struct gdbarch
*arch
;
2862 if (next_frame
->unwind
== NULL
)
2863 frame_unwind_find_by_frame (next_frame
, &next_frame
->prologue_cache
);
2865 if (next_frame
->unwind
->prev_arch
!= NULL
)
2866 arch
= next_frame
->unwind
->prev_arch (next_frame
,
2867 &next_frame
->prologue_cache
);
2869 arch
= get_frame_arch (next_frame
);
2871 next_frame
->prev_arch
.arch
= arch
;
2872 next_frame
->prev_arch
.p
= true;
2873 frame_debug_printf ("next_frame=%d -> %s",
2875 gdbarch_bfd_arch_info (arch
)->printable_name
);
2878 return next_frame
->prev_arch
.arch
;
2882 frame_unwind_caller_arch (struct frame_info
*next_frame
)
2884 next_frame
= skip_artificial_frames (next_frame
);
2886 /* We must have a non-artificial frame. The caller is supposed to check
2887 the result of frame_unwind_caller_id (), which returns NULL_FRAME_ID
2889 gdb_assert (next_frame
!= NULL
);
2891 return frame_unwind_arch (next_frame
);
2894 /* Gets the language of FRAME. */
2897 get_frame_language (struct frame_info
*frame
)
2902 gdb_assert (frame
!= NULL
);
2904 /* We determine the current frame language by looking up its
2905 associated symtab. To retrieve this symtab, we use the frame
2906 PC. However we cannot use the frame PC as is, because it
2907 usually points to the instruction following the "call", which
2908 is sometimes the first instruction of another function. So
2909 we rely on get_frame_address_in_block(), it provides us with
2910 a PC that is guaranteed to be inside the frame's code
2915 pc
= get_frame_address_in_block (frame
);
2918 catch (const gdb_exception_error
&ex
)
2920 if (ex
.error
!= NOT_AVAILABLE_ERROR
)
2926 struct compunit_symtab
*cust
= find_pc_compunit_symtab (pc
);
2929 return compunit_language (cust
);
2932 return language_unknown
;
2935 /* Stack pointer methods. */
2938 get_frame_sp (struct frame_info
*this_frame
)
2940 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
2942 /* NOTE drow/2008-06-28: gdbarch_unwind_sp could be converted to
2943 operate on THIS_FRAME now. */
2944 return gdbarch_unwind_sp (gdbarch
, this_frame
->next
);
2947 /* Return the reason why we can't unwind past FRAME. */
2949 enum unwind_stop_reason
2950 get_frame_unwind_stop_reason (struct frame_info
*frame
)
2952 /* Fill-in STOP_REASON. */
2953 get_prev_frame_always (frame
);
2954 gdb_assert (frame
->prev_p
);
2956 return frame
->stop_reason
;
2959 /* Return a string explaining REASON. */
2962 unwind_stop_reason_to_string (enum unwind_stop_reason reason
)
2966 #define SET(name, description) \
2967 case name: return _(description);
2968 #include "unwind_stop_reasons.def"
2972 internal_error (__FILE__
, __LINE__
,
2973 "Invalid frame stop reason");
2978 frame_stop_reason_string (struct frame_info
*fi
)
2980 gdb_assert (fi
->prev_p
);
2981 gdb_assert (fi
->prev
== NULL
);
2983 /* Return the specific string if we have one. */
2984 if (fi
->stop_string
!= NULL
)
2985 return fi
->stop_string
;
2987 /* Return the generic string if we have nothing better. */
2988 return unwind_stop_reason_to_string (fi
->stop_reason
);
2991 /* Return the enum symbol name of REASON as a string, to use in debug
2995 frame_stop_reason_symbol_string (enum unwind_stop_reason reason
)
2999 #define SET(name, description) \
3000 case name: return #name;
3001 #include "unwind_stop_reasons.def"
3005 internal_error (__FILE__
, __LINE__
,
3006 "Invalid frame stop reason");
3010 /* Clean up after a failed (wrong unwinder) attempt to unwind past
3014 frame_cleanup_after_sniffer (struct frame_info
*frame
)
3016 /* The sniffer should not allocate a prologue cache if it did not
3017 match this frame. */
3018 gdb_assert (frame
->prologue_cache
== NULL
);
3020 /* No sniffer should extend the frame chain; sniff based on what is
3022 gdb_assert (!frame
->prev_p
);
3024 /* The sniffer should not check the frame's ID; that's circular. */
3025 gdb_assert (frame
->this_id
.p
!= frame_id_status::COMPUTED
);
3027 /* Clear cached fields dependent on the unwinder.
3029 The previous PC is independent of the unwinder, but the previous
3030 function is not (see get_frame_address_in_block). */
3031 frame
->prev_func
.status
= CC_UNKNOWN
;
3032 frame
->prev_func
.addr
= 0;
3034 /* Discard the unwinder last, so that we can easily find it if an assertion
3035 in this function triggers. */
3036 frame
->unwind
= NULL
;
3039 /* Set FRAME's unwinder temporarily, so that we can call a sniffer.
3040 If sniffing fails, the caller should be sure to call
3041 frame_cleanup_after_sniffer. */
3044 frame_prepare_for_sniffer (struct frame_info
*frame
,
3045 const struct frame_unwind
*unwind
)
3047 gdb_assert (frame
->unwind
== NULL
);
3048 frame
->unwind
= unwind
;
3051 static struct cmd_list_element
*set_backtrace_cmdlist
;
3052 static struct cmd_list_element
*show_backtrace_cmdlist
;
3054 /* Definition of the "set backtrace" settings that are exposed as
3055 "backtrace" command options. */
3057 using boolean_option_def
3058 = gdb::option::boolean_option_def
<set_backtrace_options
>;
3060 const gdb::option::option_def set_backtrace_option_defs
[] = {
3062 boolean_option_def
{
3064 [] (set_backtrace_options
*opt
) { return &opt
->backtrace_past_main
; },
3065 show_backtrace_past_main
, /* show_cmd_cb */
3066 N_("Set whether backtraces should continue past \"main\"."),
3067 N_("Show whether backtraces should continue past \"main\"."),
3068 N_("Normally the caller of \"main\" is not of interest, so GDB will terminate\n\
3069 the backtrace at \"main\". Set this if you need to see the rest\n\
3070 of the stack trace."),
3073 boolean_option_def
{
3075 [] (set_backtrace_options
*opt
) { return &opt
->backtrace_past_entry
; },
3076 show_backtrace_past_entry
, /* show_cmd_cb */
3077 N_("Set whether backtraces should continue past the entry point of a program."),
3078 N_("Show whether backtraces should continue past the entry point of a program."),
3079 N_("Normally there are no callers beyond the entry point of a program, so GDB\n\
3080 will terminate the backtrace there. Set this if you need to see\n\
3081 the rest of the stack trace."),
3085 void _initialize_frame ();
3087 _initialize_frame ()
3089 obstack_init (&frame_cache_obstack
);
3091 frame_stash_create ();
3093 gdb::observers::target_changed
.attach (frame_observer_target_changed
,
3096 add_basic_prefix_cmd ("backtrace", class_maintenance
, _("\
3097 Set backtrace specific variables.\n\
3098 Configure backtrace variables such as the backtrace limit"),
3099 &set_backtrace_cmdlist
,
3100 0/*allow-unknown*/, &setlist
);
3101 add_show_prefix_cmd ("backtrace", class_maintenance
, _("\
3102 Show backtrace specific variables.\n\
3103 Show backtrace variables such as the backtrace limit."),
3104 &show_backtrace_cmdlist
,
3105 0/*allow-unknown*/, &showlist
);
3107 add_setshow_uinteger_cmd ("limit", class_obscure
,
3108 &user_set_backtrace_options
.backtrace_limit
, _("\
3109 Set an upper bound on the number of backtrace levels."), _("\
3110 Show the upper bound on the number of backtrace levels."), _("\
3111 No more than the specified number of frames can be displayed or examined.\n\
3112 Literal \"unlimited\" or zero means no limit."),
3114 show_backtrace_limit
,
3115 &set_backtrace_cmdlist
,
3116 &show_backtrace_cmdlist
);
3118 gdb::option::add_setshow_cmds_for_options
3119 (class_stack
, &user_set_backtrace_options
,
3120 set_backtrace_option_defs
, &set_backtrace_cmdlist
, &show_backtrace_cmdlist
);
3122 /* Debug this files internals. */
3123 add_setshow_boolean_cmd ("frame", class_maintenance
, &frame_debug
, _("\
3124 Set frame debugging."), _("\
3125 Show frame debugging."), _("\
3126 When non-zero, frame specific internal debugging is enabled."),
3129 &setdebuglist
, &showdebuglist
);