1 /* Cache and manage frames for GDB, the GNU debugger.
3 Copyright (C) 1986, 1987, 1989, 1991, 1994, 1995, 1996, 1998, 2000, 2001,
4 2002, 2003, 2004, 2007, 2008, 2009 Free Software Foundation, Inc.
6 This file is part of GDB.
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program. If not, see <http://www.gnu.org/licenses/>. */
25 #include "inferior.h" /* for inferior_ptid */
27 #include "gdb_assert.h"
28 #include "gdb_string.h"
29 #include "user-regs.h"
30 #include "gdb_obstack.h"
31 #include "dummy-frame.h"
32 #include "sentinel-frame.h"
36 #include "frame-unwind.h"
37 #include "frame-base.h"
42 #include "exceptions.h"
43 #include "gdbthread.h"
45 #include "inline-frame.h"
47 static struct frame_info *get_prev_frame_1 (struct frame_info *this_frame);
48 static struct frame_info *get_prev_frame_raw (struct frame_info *this_frame);
50 /* We keep a cache of stack frames, each of which is a "struct
51 frame_info". The innermost one gets allocated (in
52 wait_for_inferior) each time the inferior stops; current_frame
53 points to it. Additional frames get allocated (in get_prev_frame)
54 as needed, and are chained through the next and prev fields. Any
55 time that the frame cache becomes invalid (most notably when we
56 execute something, but also if we change how we interpret the
57 frames (e.g. "set heuristic-fence-post" in mips-tdep.c, or anything
58 which reads new symbols)), we should call reinit_frame_cache. */
62 /* Level of this frame. The inner-most (youngest) frame is at level
63 0. As you move towards the outer-most (oldest) frame, the level
64 increases. This is a cached value. It could just as easily be
65 computed by counting back from the selected frame to the inner
67 /* NOTE: cagney/2002-04-05: Perhaps a level of ``-1'' should be
68 reserved to indicate a bogus frame - one that has been created
69 just to keep GDB happy (GDB always needs a frame). For the
70 moment leave this as speculation. */
73 /* The frame's low-level unwinder and corresponding cache. The
74 low-level unwinder is responsible for unwinding register values
75 for the previous frame. The low-level unwind methods are
76 selected based on the presence, or otherwise, of register unwind
77 information such as CFI. */
79 const struct frame_unwind *unwind;
81 /* Cached copy of the previous frame's architecture. */
88 /* Cached copy of the previous frame's resume address. */
94 /* Cached copy of the previous frame's function address. */
101 /* This frame's ID. */
105 struct frame_id value;
108 /* The frame's high-level base methods, and corresponding cache.
109 The high level base methods are selected based on the frame's
111 const struct frame_base *base;
114 /* Pointers to the next (down, inner, younger) and previous (up,
115 outer, older) frame_info's in the frame cache. */
116 struct frame_info *next; /* down, inner, younger */
118 struct frame_info *prev; /* up, outer, older */
120 /* The reason why we could not set PREV, or UNWIND_NO_REASON if we
121 could. Only valid when PREV_P is set. */
122 enum unwind_stop_reason stop_reason;
125 /* Flag to control debugging. */
129 show_frame_debug (struct ui_file *file, int from_tty,
130 struct cmd_list_element *c, const char *value)
132 fprintf_filtered (file, _("Frame debugging is %s.\n"), value);
135 /* Flag to indicate whether backtraces should stop at main et.al. */
137 static int backtrace_past_main;
139 show_backtrace_past_main (struct ui_file *file, int from_tty,
140 struct cmd_list_element *c, const char *value)
142 fprintf_filtered (file, _("\
143 Whether backtraces should continue past \"main\" is %s.\n"),
147 static int backtrace_past_entry;
149 show_backtrace_past_entry (struct ui_file *file, int from_tty,
150 struct cmd_list_element *c, const char *value)
152 fprintf_filtered (file, _("\
153 Whether backtraces should continue past the entry point of a program is %s.\n"),
157 static int backtrace_limit = INT_MAX;
159 show_backtrace_limit (struct ui_file *file, int from_tty,
160 struct cmd_list_element *c, const char *value)
162 fprintf_filtered (file, _("\
163 An upper bound on the number of backtrace levels is %s.\n"),
169 fprint_field (struct ui_file *file, const char *name, int p, CORE_ADDR addr)
172 fprintf_unfiltered (file, "%s=%s", name, hex_string (addr));
174 fprintf_unfiltered (file, "!%s", name);
178 fprint_frame_id (struct ui_file *file, struct frame_id id)
180 fprintf_unfiltered (file, "{");
181 fprint_field (file, "stack", id.stack_addr_p, id.stack_addr);
182 fprintf_unfiltered (file, ",");
183 fprint_field (file, "code", id.code_addr_p, id.code_addr);
184 fprintf_unfiltered (file, ",");
185 fprint_field (file, "special", id.special_addr_p, id.special_addr);
187 fprintf_unfiltered (file, ",inlined=%d", id.inline_depth);
188 fprintf_unfiltered (file, "}");
192 fprint_frame_type (struct ui_file *file, enum frame_type type)
197 fprintf_unfiltered (file, "NORMAL_FRAME");
200 fprintf_unfiltered (file, "DUMMY_FRAME");
203 fprintf_unfiltered (file, "INLINE_FRAME");
206 fprintf_unfiltered (file, "SENTINEL_FRAME");
209 fprintf_unfiltered (file, "SIGTRAMP_FRAME");
212 fprintf_unfiltered (file, "ARCH_FRAME");
215 fprintf_unfiltered (file, "<unknown type>");
221 fprint_frame (struct ui_file *file, struct frame_info *fi)
225 fprintf_unfiltered (file, "<NULL frame>");
228 fprintf_unfiltered (file, "{");
229 fprintf_unfiltered (file, "level=%d", fi->level);
230 fprintf_unfiltered (file, ",");
231 fprintf_unfiltered (file, "type=");
232 if (fi->unwind != NULL)
233 fprint_frame_type (file, fi->unwind->type);
235 fprintf_unfiltered (file, "<unknown>");
236 fprintf_unfiltered (file, ",");
237 fprintf_unfiltered (file, "unwind=");
238 if (fi->unwind != NULL)
239 gdb_print_host_address (fi->unwind, file);
241 fprintf_unfiltered (file, "<unknown>");
242 fprintf_unfiltered (file, ",");
243 fprintf_unfiltered (file, "pc=");
244 if (fi->next != NULL && fi->next->prev_pc.p)
245 fprintf_unfiltered (file, "%s", hex_string (fi->next->prev_pc.value));
247 fprintf_unfiltered (file, "<unknown>");
248 fprintf_unfiltered (file, ",");
249 fprintf_unfiltered (file, "id=");
251 fprint_frame_id (file, fi->this_id.value);
253 fprintf_unfiltered (file, "<unknown>");
254 fprintf_unfiltered (file, ",");
255 fprintf_unfiltered (file, "func=");
256 if (fi->next != NULL && fi->next->prev_func.p)
257 fprintf_unfiltered (file, "%s", hex_string (fi->next->prev_func.addr));
259 fprintf_unfiltered (file, "<unknown>");
260 fprintf_unfiltered (file, "}");
263 /* Given FRAME, return the enclosing normal frame for inlined
264 function frames. Otherwise return the original frame. */
266 static struct frame_info *
267 skip_inlined_frames (struct frame_info *frame)
269 while (get_frame_type (frame) == INLINE_FRAME)
270 frame = get_prev_frame (frame);
275 /* Return a frame uniq ID that can be used to, later, re-find the
279 get_frame_id (struct frame_info *fi)
283 return null_frame_id;
288 fprintf_unfiltered (gdb_stdlog, "{ get_frame_id (fi=%d) ",
290 /* Find the unwinder. */
291 if (fi->unwind == NULL)
292 fi->unwind = frame_unwind_find_by_frame (fi, &fi->prologue_cache);
293 /* Find THIS frame's ID. */
294 fi->unwind->this_id (fi, &fi->prologue_cache, &fi->this_id.value);
298 fprintf_unfiltered (gdb_stdlog, "-> ");
299 fprint_frame_id (gdb_stdlog, fi->this_id.value);
300 fprintf_unfiltered (gdb_stdlog, " }\n");
303 return fi->this_id.value;
307 get_stack_frame_id (struct frame_info *next_frame)
309 return get_frame_id (skip_inlined_frames (next_frame));
313 frame_unwind_caller_id (struct frame_info *next_frame)
315 struct frame_info *this_frame;
317 /* Use get_prev_frame_1, and not get_prev_frame. The latter will truncate
318 the frame chain, leading to this function unintentionally
319 returning a null_frame_id (e.g., when a caller requests the frame
320 ID of "main()"s caller. */
322 next_frame = skip_inlined_frames (next_frame);
323 this_frame = get_prev_frame_1 (next_frame);
325 return get_frame_id (skip_inlined_frames (this_frame));
327 return null_frame_id;
330 const struct frame_id null_frame_id; /* All zeros. */
333 frame_id_build_special (CORE_ADDR stack_addr, CORE_ADDR code_addr,
334 CORE_ADDR special_addr)
336 struct frame_id id = null_frame_id;
337 id.stack_addr = stack_addr;
339 id.code_addr = code_addr;
341 id.special_addr = special_addr;
342 id.special_addr_p = 1;
347 frame_id_build (CORE_ADDR stack_addr, CORE_ADDR code_addr)
349 struct frame_id id = null_frame_id;
350 id.stack_addr = stack_addr;
352 id.code_addr = code_addr;
358 frame_id_build_wild (CORE_ADDR stack_addr)
360 struct frame_id id = null_frame_id;
361 id.stack_addr = stack_addr;
367 frame_id_p (struct frame_id l)
370 /* The frame is valid iff it has a valid stack address. */
374 fprintf_unfiltered (gdb_stdlog, "{ frame_id_p (l=");
375 fprint_frame_id (gdb_stdlog, l);
376 fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", p);
382 frame_id_inlined_p (struct frame_id l)
387 return (l.inline_depth != 0);
391 frame_id_eq (struct frame_id l, struct frame_id r)
394 if (!l.stack_addr_p || !r.stack_addr_p)
395 /* Like a NaN, if either ID is invalid, the result is false.
396 Note that a frame ID is invalid iff it is the null frame ID. */
398 else if (l.stack_addr != r.stack_addr)
399 /* If .stack addresses are different, the frames are different. */
401 else if (l.code_addr_p && r.code_addr_p && l.code_addr != r.code_addr)
402 /* An invalid code addr is a wild card. If .code addresses are
403 different, the frames are different. */
405 else if (l.special_addr_p && r.special_addr_p
406 && l.special_addr != r.special_addr)
407 /* An invalid special addr is a wild card (or unused). Otherwise
408 if special addresses are different, the frames are different. */
410 else if (l.inline_depth != r.inline_depth)
411 /* If inline depths are different, the frames must be different. */
414 /* Frames are equal. */
419 fprintf_unfiltered (gdb_stdlog, "{ frame_id_eq (l=");
420 fprint_frame_id (gdb_stdlog, l);
421 fprintf_unfiltered (gdb_stdlog, ",r=");
422 fprint_frame_id (gdb_stdlog, r);
423 fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", eq);
428 /* Safety net to check whether frame ID L should be inner to
429 frame ID R, according to their stack addresses.
431 This method cannot be used to compare arbitrary frames, as the
432 ranges of valid stack addresses may be discontiguous (e.g. due
435 However, it can be used as safety net to discover invalid frame
436 IDs in certain circumstances. Assuming that NEXT is the immediate
437 inner frame to THIS and that NEXT and THIS are both NORMAL frames:
439 * The stack address of NEXT must be inner-than-or-equal to the stack
442 Therefore, if frame_id_inner (THIS, NEXT) holds, some unwind
445 * If NEXT and THIS have different stack addresses, no other frame
446 in the frame chain may have a stack address in between.
448 Therefore, if frame_id_inner (TEST, THIS) holds, but
449 frame_id_inner (TEST, NEXT) does not hold, TEST cannot refer
450 to a valid frame in the frame chain.
452 The sanity checks above cannot be performed when a SIGTRAMP frame
453 is involved, because signal handlers might be executed on a different
454 stack than the stack used by the routine that caused the signal
455 to be raised. This can happen for instance when a thread exceeds
456 its maximum stack size. In this case, certain compilers implement
457 a stack overflow strategy that cause the handler to be run on a
461 frame_id_inner (struct gdbarch *gdbarch, struct frame_id l, struct frame_id r)
464 if (!l.stack_addr_p || !r.stack_addr_p)
465 /* Like NaN, any operation involving an invalid ID always fails. */
467 else if (l.inline_depth > r.inline_depth
468 && l.stack_addr == r.stack_addr
469 && l.code_addr_p == r.code_addr_p
470 && l.special_addr_p == r.special_addr_p
471 && l.special_addr == r.special_addr)
473 /* Same function, different inlined functions. */
474 struct block *lb, *rb;
476 gdb_assert (l.code_addr_p && r.code_addr_p);
478 lb = block_for_pc (l.code_addr);
479 rb = block_for_pc (r.code_addr);
481 if (lb == NULL || rb == NULL)
482 /* Something's gone wrong. */
485 /* This will return true if LB and RB are the same block, or
486 if the block with the smaller depth lexically encloses the
487 block with the greater depth. */
488 inner = contained_in (lb, rb);
491 /* Only return non-zero when strictly inner than. Note that, per
492 comment in "frame.h", there is some fuzz here. Frameless
493 functions are not strictly inner than (same .stack but
494 different .code and/or .special address). */
495 inner = gdbarch_inner_than (gdbarch, l.stack_addr, r.stack_addr);
498 fprintf_unfiltered (gdb_stdlog, "{ frame_id_inner (l=");
499 fprint_frame_id (gdb_stdlog, l);
500 fprintf_unfiltered (gdb_stdlog, ",r=");
501 fprint_frame_id (gdb_stdlog, r);
502 fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", inner);
508 frame_find_by_id (struct frame_id id)
510 struct frame_info *frame, *prev_frame;
512 /* ZERO denotes the null frame, let the caller decide what to do
513 about it. Should it instead return get_current_frame()? */
514 if (!frame_id_p (id))
517 for (frame = get_current_frame (); ; frame = prev_frame)
519 struct frame_id this = get_frame_id (frame);
520 if (frame_id_eq (id, this))
521 /* An exact match. */
524 prev_frame = get_prev_frame (frame);
528 /* As a safety net to avoid unnecessary backtracing while trying
529 to find an invalid ID, we check for a common situation where
530 we can detect from comparing stack addresses that no other
531 frame in the current frame chain can have this ID. See the
532 comment at frame_id_inner for details. */
533 if (get_frame_type (frame) == NORMAL_FRAME
534 && !frame_id_inner (get_frame_arch (frame), id, this)
535 && frame_id_inner (get_frame_arch (prev_frame), id,
536 get_frame_id (prev_frame)))
543 frame_unwind_pc (struct frame_info *this_frame)
545 if (!this_frame->prev_pc.p)
548 if (gdbarch_unwind_pc_p (frame_unwind_arch (this_frame)))
550 /* The right way. The `pure' way. The one true way. This
551 method depends solely on the register-unwind code to
552 determine the value of registers in THIS frame, and hence
553 the value of this frame's PC (resume address). A typical
554 implementation is no more than:
556 frame_unwind_register (this_frame, ISA_PC_REGNUM, buf);
557 return extract_unsigned_integer (buf, size of ISA_PC_REGNUM);
559 Note: this method is very heavily dependent on a correct
560 register-unwind implementation, it pays to fix that
561 method first; this method is frame type agnostic, since
562 it only deals with register values, it works with any
563 frame. This is all in stark contrast to the old
564 FRAME_SAVED_PC which would try to directly handle all the
565 different ways that a PC could be unwound. */
566 pc = gdbarch_unwind_pc (frame_unwind_arch (this_frame), this_frame);
569 internal_error (__FILE__, __LINE__, _("No unwind_pc method"));
570 this_frame->prev_pc.value = pc;
571 this_frame->prev_pc.p = 1;
573 fprintf_unfiltered (gdb_stdlog,
574 "{ frame_unwind_caller_pc (this_frame=%d) -> 0x%s }\n",
576 hex_string (this_frame->prev_pc.value));
578 return this_frame->prev_pc.value;
582 frame_unwind_caller_pc (struct frame_info *this_frame)
584 return frame_unwind_pc (skip_inlined_frames (this_frame));
588 get_frame_func (struct frame_info *this_frame)
590 struct frame_info *next_frame = this_frame->next;
592 if (!next_frame->prev_func.p)
594 /* Make certain that this, and not the adjacent, function is
596 CORE_ADDR addr_in_block = get_frame_address_in_block (this_frame);
597 next_frame->prev_func.p = 1;
598 next_frame->prev_func.addr = get_pc_function_start (addr_in_block);
600 fprintf_unfiltered (gdb_stdlog,
601 "{ get_frame_func (this_frame=%d) -> %s }\n",
603 hex_string (next_frame->prev_func.addr));
605 return next_frame->prev_func.addr;
609 do_frame_register_read (void *src, int regnum, gdb_byte *buf)
611 return frame_register_read (src, regnum, buf);
615 frame_save_as_regcache (struct frame_info *this_frame)
617 struct regcache *regcache = regcache_xmalloc (get_frame_arch (this_frame));
618 struct cleanup *cleanups = make_cleanup_regcache_xfree (regcache);
619 regcache_save (regcache, do_frame_register_read, this_frame);
620 discard_cleanups (cleanups);
625 frame_pop (struct frame_info *this_frame)
627 struct frame_info *prev_frame;
628 struct regcache *scratch;
629 struct cleanup *cleanups;
631 if (get_frame_type (this_frame) == DUMMY_FRAME)
633 /* Popping a dummy frame involves restoring more than just registers.
634 dummy_frame_pop does all the work. */
635 dummy_frame_pop (get_frame_id (this_frame));
639 /* Ensure that we have a frame to pop to. */
640 prev_frame = get_prev_frame_1 (this_frame);
643 error (_("Cannot pop the initial frame."));
645 /* Make a copy of all the register values unwound from this frame.
646 Save them in a scratch buffer so that there isn't a race between
647 trying to extract the old values from the current regcache while
648 at the same time writing new values into that same cache. */
649 scratch = frame_save_as_regcache (prev_frame);
650 cleanups = make_cleanup_regcache_xfree (scratch);
652 /* FIXME: cagney/2003-03-16: It should be possible to tell the
653 target's register cache that it is about to be hit with a burst
654 register transfer and that the sequence of register writes should
655 be batched. The pair target_prepare_to_store() and
656 target_store_registers() kind of suggest this functionality.
657 Unfortunately, they don't implement it. Their lack of a formal
658 definition can lead to targets writing back bogus values
659 (arguably a bug in the target code mind). */
660 /* Now copy those saved registers into the current regcache.
661 Here, regcache_cpy() calls regcache_restore(). */
662 regcache_cpy (get_current_regcache (), scratch);
663 do_cleanups (cleanups);
665 /* We've made right mess of GDB's local state, just discard
667 reinit_frame_cache ();
671 frame_register_unwind (struct frame_info *frame, int regnum,
672 int *optimizedp, enum lval_type *lvalp,
673 CORE_ADDR *addrp, int *realnump, gdb_byte *bufferp)
677 /* Require all but BUFFERP to be valid. A NULL BUFFERP indicates
678 that the value proper does not need to be fetched. */
679 gdb_assert (optimizedp != NULL);
680 gdb_assert (lvalp != NULL);
681 gdb_assert (addrp != NULL);
682 gdb_assert (realnump != NULL);
683 /* gdb_assert (bufferp != NULL); */
685 value = frame_unwind_register_value (frame, regnum);
687 gdb_assert (value != NULL);
689 *optimizedp = value_optimized_out (value);
690 *lvalp = VALUE_LVAL (value);
691 *addrp = value_address (value);
692 *realnump = VALUE_REGNUM (value);
695 memcpy (bufferp, value_contents_all (value),
696 TYPE_LENGTH (value_type (value)));
698 /* Dispose of the new value. This prevents watchpoints from
699 trying to watch the saved frame pointer. */
700 release_value (value);
705 frame_register (struct frame_info *frame, int regnum,
706 int *optimizedp, enum lval_type *lvalp,
707 CORE_ADDR *addrp, int *realnump, gdb_byte *bufferp)
709 /* Require all but BUFFERP to be valid. A NULL BUFFERP indicates
710 that the value proper does not need to be fetched. */
711 gdb_assert (optimizedp != NULL);
712 gdb_assert (lvalp != NULL);
713 gdb_assert (addrp != NULL);
714 gdb_assert (realnump != NULL);
715 /* gdb_assert (bufferp != NULL); */
717 /* Obtain the register value by unwinding the register from the next
718 (more inner frame). */
719 gdb_assert (frame != NULL && frame->next != NULL);
720 frame_register_unwind (frame->next, regnum, optimizedp, lvalp, addrp,
725 frame_unwind_register (struct frame_info *frame, int regnum, gdb_byte *buf)
731 frame_register_unwind (frame, regnum, &optimized, &lval, &addr,
736 get_frame_register (struct frame_info *frame,
737 int regnum, gdb_byte *buf)
739 frame_unwind_register (frame->next, regnum, buf);
743 frame_unwind_register_value (struct frame_info *frame, int regnum)
745 struct gdbarch *gdbarch;
748 gdb_assert (frame != NULL);
749 gdbarch = frame_unwind_arch (frame);
753 fprintf_unfiltered (gdb_stdlog, "\
754 { frame_unwind_register_value (frame=%d,regnum=%d(%s),...) ",
755 frame->level, regnum,
756 user_reg_map_regnum_to_name (gdbarch, regnum));
759 /* Find the unwinder. */
760 if (frame->unwind == NULL)
761 frame->unwind = frame_unwind_find_by_frame (frame, &frame->prologue_cache);
763 /* Ask this frame to unwind its register. */
764 value = frame->unwind->prev_register (frame, &frame->prologue_cache, regnum);
768 fprintf_unfiltered (gdb_stdlog, "->");
769 if (value_optimized_out (value))
770 fprintf_unfiltered (gdb_stdlog, " optimized out");
773 if (VALUE_LVAL (value) == lval_register)
774 fprintf_unfiltered (gdb_stdlog, " register=%d",
775 VALUE_REGNUM (value));
776 else if (VALUE_LVAL (value) == lval_memory)
777 fprintf_unfiltered (gdb_stdlog, " address=%s",
779 value_address (value)));
781 fprintf_unfiltered (gdb_stdlog, " computed");
783 if (value_lazy (value))
784 fprintf_unfiltered (gdb_stdlog, " lazy");
788 const gdb_byte *buf = value_contents (value);
790 fprintf_unfiltered (gdb_stdlog, " bytes=");
791 fprintf_unfiltered (gdb_stdlog, "[");
792 for (i = 0; i < register_size (gdbarch, regnum); i++)
793 fprintf_unfiltered (gdb_stdlog, "%02x", buf[i]);
794 fprintf_unfiltered (gdb_stdlog, "]");
798 fprintf_unfiltered (gdb_stdlog, " }\n");
805 get_frame_register_value (struct frame_info *frame, int regnum)
807 return frame_unwind_register_value (frame->next, regnum);
811 frame_unwind_register_signed (struct frame_info *frame, int regnum)
813 gdb_byte buf[MAX_REGISTER_SIZE];
814 frame_unwind_register (frame, regnum, buf);
815 return extract_signed_integer (buf, register_size (frame_unwind_arch (frame),
820 get_frame_register_signed (struct frame_info *frame, int regnum)
822 return frame_unwind_register_signed (frame->next, regnum);
826 frame_unwind_register_unsigned (struct frame_info *frame, int regnum)
828 gdb_byte buf[MAX_REGISTER_SIZE];
829 frame_unwind_register (frame, regnum, buf);
830 return extract_unsigned_integer (buf, register_size (frame_unwind_arch (frame),
835 get_frame_register_unsigned (struct frame_info *frame, int regnum)
837 return frame_unwind_register_unsigned (frame->next, regnum);
841 put_frame_register (struct frame_info *frame, int regnum,
844 struct gdbarch *gdbarch = get_frame_arch (frame);
849 frame_register (frame, regnum, &optim, &lval, &addr, &realnum, NULL);
851 error (_("Attempt to assign to a value that was optimized out."));
856 /* FIXME: write_memory doesn't yet take constant buffers.
858 gdb_byte tmp[MAX_REGISTER_SIZE];
859 memcpy (tmp, buf, register_size (gdbarch, regnum));
860 write_memory (addr, tmp, register_size (gdbarch, regnum));
864 regcache_cooked_write (get_current_regcache (), realnum, buf);
867 error (_("Attempt to assign to an unmodifiable value."));
871 /* frame_register_read ()
873 Find and return the value of REGNUM for the specified stack frame.
874 The number of bytes copied is REGISTER_SIZE (REGNUM).
876 Returns 0 if the register value could not be found. */
879 frame_register_read (struct frame_info *frame, int regnum,
886 frame_register (frame, regnum, &optimized, &lval, &addr, &realnum, myaddr);
892 get_frame_register_bytes (struct frame_info *frame, int regnum,
893 CORE_ADDR offset, int len, gdb_byte *myaddr)
895 struct gdbarch *gdbarch = get_frame_arch (frame);
900 /* Skip registers wholly inside of OFFSET. */
901 while (offset >= register_size (gdbarch, regnum))
903 offset -= register_size (gdbarch, regnum);
907 /* Ensure that we will not read beyond the end of the register file.
908 This can only ever happen if the debug information is bad. */
910 numregs = gdbarch_num_regs (gdbarch) + gdbarch_num_pseudo_regs (gdbarch);
911 for (i = regnum; i < numregs; i++)
913 int thissize = register_size (gdbarch, i);
915 break; /* This register is not available on this architecture. */
920 warning (_("Bad debug information detected: "
921 "Attempt to read %d bytes from registers."), len);
928 int curr_len = register_size (gdbarch, regnum) - offset;
932 if (curr_len == register_size (gdbarch, regnum))
934 if (!frame_register_read (frame, regnum, myaddr))
939 gdb_byte buf[MAX_REGISTER_SIZE];
940 if (!frame_register_read (frame, regnum, buf))
942 memcpy (myaddr, buf + offset, curr_len);
955 put_frame_register_bytes (struct frame_info *frame, int regnum,
956 CORE_ADDR offset, int len, const gdb_byte *myaddr)
958 struct gdbarch *gdbarch = get_frame_arch (frame);
960 /* Skip registers wholly inside of OFFSET. */
961 while (offset >= register_size (gdbarch, regnum))
963 offset -= register_size (gdbarch, regnum);
970 int curr_len = register_size (gdbarch, regnum) - offset;
974 if (curr_len == register_size (gdbarch, regnum))
976 put_frame_register (frame, regnum, myaddr);
980 gdb_byte buf[MAX_REGISTER_SIZE];
981 frame_register_read (frame, regnum, buf);
982 memcpy (buf + offset, myaddr, curr_len);
983 put_frame_register (frame, regnum, buf);
993 /* Create a sentinel frame. */
995 static struct frame_info *
996 create_sentinel_frame (struct regcache *regcache)
998 struct frame_info *frame = FRAME_OBSTACK_ZALLOC (struct frame_info);
1000 /* Explicitly initialize the sentinel frame's cache. Provide it
1001 with the underlying regcache. In the future additional
1002 information, such as the frame's thread will be added. */
1003 frame->prologue_cache = sentinel_frame_cache (regcache);
1004 /* For the moment there is only one sentinel frame implementation. */
1005 frame->unwind = sentinel_frame_unwind;
1006 /* Link this frame back to itself. The frame is self referential
1007 (the unwound PC is the same as the pc), so make it so. */
1008 frame->next = frame;
1009 /* Make the sentinel frame's ID valid, but invalid. That way all
1010 comparisons with it should fail. */
1011 frame->this_id.p = 1;
1012 frame->this_id.value = null_frame_id;
1015 fprintf_unfiltered (gdb_stdlog, "{ create_sentinel_frame (...) -> ");
1016 fprint_frame (gdb_stdlog, frame);
1017 fprintf_unfiltered (gdb_stdlog, " }\n");
1022 /* Info about the innermost stack frame (contents of FP register) */
1024 static struct frame_info *current_frame;
1026 /* Cache for frame addresses already read by gdb. Valid only while
1027 inferior is stopped. Control variables for the frame cache should
1028 be local to this module. */
1030 static struct obstack frame_cache_obstack;
1033 frame_obstack_zalloc (unsigned long size)
1035 void *data = obstack_alloc (&frame_cache_obstack, size);
1036 memset (data, 0, size);
1040 /* Return the innermost (currently executing) stack frame. This is
1041 split into two functions. The function unwind_to_current_frame()
1042 is wrapped in catch exceptions so that, even when the unwind of the
1043 sentinel frame fails, the function still returns a stack frame. */
1046 unwind_to_current_frame (struct ui_out *ui_out, void *args)
1048 struct frame_info *frame = get_prev_frame (args);
1049 /* A sentinel frame can fail to unwind, e.g., because its PC value
1050 lands in somewhere like start. */
1053 current_frame = frame;
1058 get_current_frame (void)
1060 /* First check, and report, the lack of registers. Having GDB
1061 report "No stack!" or "No memory" when the target doesn't even
1062 have registers is very confusing. Besides, "printcmd.exp"
1063 explicitly checks that ``print $pc'' with no registers prints "No
1065 if (!target_has_registers)
1066 error (_("No registers."));
1067 if (!target_has_stack)
1068 error (_("No stack."));
1069 if (!target_has_memory)
1070 error (_("No memory."));
1071 if (ptid_equal (inferior_ptid, null_ptid))
1072 error (_("No selected thread."));
1073 if (is_exited (inferior_ptid))
1074 error (_("Invalid selected thread."));
1075 if (is_executing (inferior_ptid))
1076 error (_("Target is executing."));
1078 if (current_frame == NULL)
1080 struct frame_info *sentinel_frame =
1081 create_sentinel_frame (get_current_regcache ());
1082 if (catch_exceptions (uiout, unwind_to_current_frame, sentinel_frame,
1083 RETURN_MASK_ERROR) != 0)
1085 /* Oops! Fake a current frame? Is this useful? It has a PC
1086 of zero, for instance. */
1087 current_frame = sentinel_frame;
1090 return current_frame;
1093 /* The "selected" stack frame is used by default for local and arg
1094 access. May be zero, for no selected frame. */
1096 static struct frame_info *selected_frame;
1099 has_stack_frames (void)
1101 if (!target_has_registers || !target_has_stack || !target_has_memory)
1104 /* No current inferior, no frame. */
1105 if (ptid_equal (inferior_ptid, null_ptid))
1108 /* Don't try to read from a dead thread. */
1109 if (is_exited (inferior_ptid))
1112 /* ... or from a spinning thread. */
1113 if (is_executing (inferior_ptid))
1119 /* Return the selected frame. Always non-NULL (unless there isn't an
1120 inferior sufficient for creating a frame) in which case an error is
1124 get_selected_frame (const char *message)
1126 if (selected_frame == NULL)
1128 if (message != NULL && !has_stack_frames ())
1129 error (("%s"), message);
1130 /* Hey! Don't trust this. It should really be re-finding the
1131 last selected frame of the currently selected thread. This,
1132 though, is better than nothing. */
1133 select_frame (get_current_frame ());
1135 /* There is always a frame. */
1136 gdb_assert (selected_frame != NULL);
1137 return selected_frame;
1140 /* This is a variant of get_selected_frame() which can be called when
1141 the inferior does not have a frame; in that case it will return
1142 NULL instead of calling error(). */
1145 deprecated_safe_get_selected_frame (void)
1147 if (!has_stack_frames ())
1149 return get_selected_frame (NULL);
1152 /* Select frame FI (or NULL - to invalidate the current frame). */
1155 select_frame (struct frame_info *fi)
1159 selected_frame = fi;
1160 /* NOTE: cagney/2002-05-04: FI can be NULL. This occurs when the
1161 frame is being invalidated. */
1162 if (deprecated_selected_frame_level_changed_hook)
1163 deprecated_selected_frame_level_changed_hook (frame_relative_level (fi));
1165 /* FIXME: kseitz/2002-08-28: It would be nice to call
1166 selected_frame_level_changed_event() right here, but due to limitations
1167 in the current interfaces, we would end up flooding UIs with events
1168 because select_frame() is used extensively internally.
1170 Once we have frame-parameterized frame (and frame-related) commands,
1171 the event notification can be moved here, since this function will only
1172 be called when the user's selected frame is being changed. */
1174 /* Ensure that symbols for this frame are read in. Also, determine the
1175 source language of this frame, and switch to it if desired. */
1178 /* We retrieve the frame's symtab by using the frame PC. However
1179 we cannot use the frame PC as-is, because it usually points to
1180 the instruction following the "call", which is sometimes the
1181 first instruction of another function. So we rely on
1182 get_frame_address_in_block() which provides us with a PC which
1183 is guaranteed to be inside the frame's code block. */
1184 s = find_pc_symtab (get_frame_address_in_block (fi));
1186 && s->language != current_language->la_language
1187 && s->language != language_unknown
1188 && language_mode == language_mode_auto)
1190 set_language (s->language);
1195 /* Create an arbitrary (i.e. address specified by user) or innermost frame.
1196 Always returns a non-NULL value. */
1199 create_new_frame (CORE_ADDR addr, CORE_ADDR pc)
1201 struct frame_info *fi;
1205 fprintf_unfiltered (gdb_stdlog,
1206 "{ create_new_frame (addr=%s, pc=%s) ",
1207 hex_string (addr), hex_string (pc));
1210 fi = FRAME_OBSTACK_ZALLOC (struct frame_info);
1212 fi->next = create_sentinel_frame (get_current_regcache ());
1214 /* Set/update this frame's cached PC value, found in the next frame.
1215 Do this before looking for this frame's unwinder. A sniffer is
1216 very likely to read this, and the corresponding unwinder is
1217 entitled to rely that the PC doesn't magically change. */
1218 fi->next->prev_pc.value = pc;
1219 fi->next->prev_pc.p = 1;
1221 /* Select/initialize both the unwind function and the frame's type
1223 fi->unwind = frame_unwind_find_by_frame (fi, &fi->prologue_cache);
1226 fi->this_id.value = frame_id_build (addr, pc);
1230 fprintf_unfiltered (gdb_stdlog, "-> ");
1231 fprint_frame (gdb_stdlog, fi);
1232 fprintf_unfiltered (gdb_stdlog, " }\n");
1238 /* Return the frame that THIS_FRAME calls (NULL if THIS_FRAME is the
1239 innermost frame). Be careful to not fall off the bottom of the
1240 frame chain and onto the sentinel frame. */
1243 get_next_frame (struct frame_info *this_frame)
1245 if (this_frame->level > 0)
1246 return this_frame->next;
1251 /* Observer for the target_changed event. */
1254 frame_observer_target_changed (struct target_ops *target)
1256 reinit_frame_cache ();
1259 /* Flush the entire frame cache. */
1262 reinit_frame_cache (void)
1264 struct frame_info *fi;
1266 /* Tear down all frame caches. */
1267 for (fi = current_frame; fi != NULL; fi = fi->prev)
1269 if (fi->prologue_cache && fi->unwind->dealloc_cache)
1270 fi->unwind->dealloc_cache (fi, fi->prologue_cache);
1271 if (fi->base_cache && fi->base->unwind->dealloc_cache)
1272 fi->base->unwind->dealloc_cache (fi, fi->base_cache);
1275 /* Since we can't really be sure what the first object allocated was */
1276 obstack_free (&frame_cache_obstack, 0);
1277 obstack_init (&frame_cache_obstack);
1279 if (current_frame != NULL)
1280 annotate_frames_invalid ();
1282 current_frame = NULL; /* Invalidate cache */
1283 select_frame (NULL);
1285 fprintf_unfiltered (gdb_stdlog, "{ reinit_frame_cache () }\n");
1288 /* Find where a register is saved (in memory or another register).
1289 The result of frame_register_unwind is just where it is saved
1290 relative to this particular frame. */
1293 frame_register_unwind_location (struct frame_info *this_frame, int regnum,
1294 int *optimizedp, enum lval_type *lvalp,
1295 CORE_ADDR *addrp, int *realnump)
1297 gdb_assert (this_frame == NULL || this_frame->level >= 0);
1299 while (this_frame != NULL)
1301 frame_register_unwind (this_frame, regnum, optimizedp, lvalp,
1302 addrp, realnump, NULL);
1307 if (*lvalp != lval_register)
1311 this_frame = get_next_frame (this_frame);
1315 /* Return a "struct frame_info" corresponding to the frame that called
1316 THIS_FRAME. Returns NULL if there is no such frame.
1318 Unlike get_prev_frame, this function always tries to unwind the
1321 static struct frame_info *
1322 get_prev_frame_1 (struct frame_info *this_frame)
1324 struct frame_id this_id;
1325 struct gdbarch *gdbarch;
1327 gdb_assert (this_frame != NULL);
1328 gdbarch = get_frame_arch (this_frame);
1332 fprintf_unfiltered (gdb_stdlog, "{ get_prev_frame_1 (this_frame=");
1333 if (this_frame != NULL)
1334 fprintf_unfiltered (gdb_stdlog, "%d", this_frame->level);
1336 fprintf_unfiltered (gdb_stdlog, "<NULL>");
1337 fprintf_unfiltered (gdb_stdlog, ") ");
1340 /* Only try to do the unwind once. */
1341 if (this_frame->prev_p)
1345 fprintf_unfiltered (gdb_stdlog, "-> ");
1346 fprint_frame (gdb_stdlog, this_frame->prev);
1347 fprintf_unfiltered (gdb_stdlog, " // cached \n");
1349 return this_frame->prev;
1352 /* If the frame unwinder hasn't been selected yet, we must do so
1353 before setting prev_p; otherwise the check for misbehaved
1354 sniffers will think that this frame's sniffer tried to unwind
1355 further (see frame_cleanup_after_sniffer). */
1356 if (this_frame->unwind == NULL)
1358 = frame_unwind_find_by_frame (this_frame, &this_frame->prologue_cache);
1360 this_frame->prev_p = 1;
1361 this_frame->stop_reason = UNWIND_NO_REASON;
1363 /* If we are unwinding from an inline frame, all of the below tests
1364 were already performed when we unwound from the next non-inline
1365 frame. We must skip them, since we can not get THIS_FRAME's ID
1366 until we have unwound all the way down to the previous non-inline
1368 if (get_frame_type (this_frame) == INLINE_FRAME)
1369 return get_prev_frame_raw (this_frame);
1371 /* Check that this frame's ID was valid. If it wasn't, don't try to
1372 unwind to the prev frame. Be careful to not apply this test to
1373 the sentinel frame. */
1374 this_id = get_frame_id (this_frame);
1375 if (this_frame->level >= 0 && !frame_id_p (this_id))
1379 fprintf_unfiltered (gdb_stdlog, "-> ");
1380 fprint_frame (gdb_stdlog, NULL);
1381 fprintf_unfiltered (gdb_stdlog, " // this ID is NULL }\n");
1383 this_frame->stop_reason = UNWIND_NULL_ID;
1387 /* Check that this frame's ID isn't inner to (younger, below, next)
1388 the next frame. This happens when a frame unwind goes backwards.
1389 This check is valid only if this frame and the next frame are NORMAL.
1390 See the comment at frame_id_inner for details. */
1391 if (get_frame_type (this_frame) == NORMAL_FRAME
1392 && this_frame->next->unwind->type == NORMAL_FRAME
1393 && frame_id_inner (get_frame_arch (this_frame->next), this_id,
1394 get_frame_id (this_frame->next)))
1398 fprintf_unfiltered (gdb_stdlog, "-> ");
1399 fprint_frame (gdb_stdlog, NULL);
1400 fprintf_unfiltered (gdb_stdlog, " // this frame ID is inner }\n");
1402 this_frame->stop_reason = UNWIND_INNER_ID;
1406 /* Check that this and the next frame are not identical. If they
1407 are, there is most likely a stack cycle. As with the inner-than
1408 test above, avoid comparing the inner-most and sentinel frames. */
1409 if (this_frame->level > 0
1410 && frame_id_eq (this_id, get_frame_id (this_frame->next)))
1414 fprintf_unfiltered (gdb_stdlog, "-> ");
1415 fprint_frame (gdb_stdlog, NULL);
1416 fprintf_unfiltered (gdb_stdlog, " // this frame has same ID }\n");
1418 this_frame->stop_reason = UNWIND_SAME_ID;
1422 /* Check that this and the next frame do not unwind the PC register
1423 to the same memory location. If they do, then even though they
1424 have different frame IDs, the new frame will be bogus; two
1425 functions can't share a register save slot for the PC. This can
1426 happen when the prologue analyzer finds a stack adjustment, but
1429 This check does assume that the "PC register" is roughly a
1430 traditional PC, even if the gdbarch_unwind_pc method adjusts
1431 it (we do not rely on the value, only on the unwound PC being
1432 dependent on this value). A potential improvement would be
1433 to have the frame prev_pc method and the gdbarch unwind_pc
1434 method set the same lval and location information as
1435 frame_register_unwind. */
1436 if (this_frame->level > 0
1437 && gdbarch_pc_regnum (gdbarch) >= 0
1438 && get_frame_type (this_frame) == NORMAL_FRAME
1439 && (get_frame_type (this_frame->next) == NORMAL_FRAME
1440 || get_frame_type (this_frame->next) == INLINE_FRAME))
1442 int optimized, realnum, nrealnum;
1443 enum lval_type lval, nlval;
1444 CORE_ADDR addr, naddr;
1446 frame_register_unwind_location (this_frame,
1447 gdbarch_pc_regnum (gdbarch),
1448 &optimized, &lval, &addr, &realnum);
1449 frame_register_unwind_location (get_next_frame (this_frame),
1450 gdbarch_pc_regnum (gdbarch),
1451 &optimized, &nlval, &naddr, &nrealnum);
1453 if ((lval == lval_memory && lval == nlval && addr == naddr)
1454 || (lval == lval_register && lval == nlval && realnum == nrealnum))
1458 fprintf_unfiltered (gdb_stdlog, "-> ");
1459 fprint_frame (gdb_stdlog, NULL);
1460 fprintf_unfiltered (gdb_stdlog, " // no saved PC }\n");
1463 this_frame->stop_reason = UNWIND_NO_SAVED_PC;
1464 this_frame->prev = NULL;
1469 return get_prev_frame_raw (this_frame);
1472 /* Construct a new "struct frame_info" and link it previous to
1475 static struct frame_info *
1476 get_prev_frame_raw (struct frame_info *this_frame)
1478 struct frame_info *prev_frame;
1480 /* Allocate the new frame but do not wire it in to the frame chain.
1481 Some (bad) code in INIT_FRAME_EXTRA_INFO tries to look along
1482 frame->next to pull some fancy tricks (of course such code is, by
1483 definition, recursive). Try to prevent it.
1485 There is no reason to worry about memory leaks, should the
1486 remainder of the function fail. The allocated memory will be
1487 quickly reclaimed when the frame cache is flushed, and the `we've
1488 been here before' check above will stop repeated memory
1489 allocation calls. */
1490 prev_frame = FRAME_OBSTACK_ZALLOC (struct frame_info);
1491 prev_frame->level = this_frame->level + 1;
1493 /* Don't yet compute ->unwind (and hence ->type). It is computed
1494 on-demand in get_frame_type, frame_register_unwind, and
1497 /* Don't yet compute the frame's ID. It is computed on-demand by
1500 /* The unwound frame ID is validate at the start of this function,
1501 as part of the logic to decide if that frame should be further
1502 unwound, and not here while the prev frame is being created.
1503 Doing this makes it possible for the user to examine a frame that
1504 has an invalid frame ID.
1506 Some very old VAX code noted: [...] For the sake of argument,
1507 suppose that the stack is somewhat trashed (which is one reason
1508 that "info frame" exists). So, return 0 (indicating we don't
1509 know the address of the arglist) if we don't know what frame this
1513 this_frame->prev = prev_frame;
1514 prev_frame->next = this_frame;
1518 fprintf_unfiltered (gdb_stdlog, "-> ");
1519 fprint_frame (gdb_stdlog, prev_frame);
1520 fprintf_unfiltered (gdb_stdlog, " }\n");
1526 /* Debug routine to print a NULL frame being returned. */
1529 frame_debug_got_null_frame (struct frame_info *this_frame,
1534 fprintf_unfiltered (gdb_stdlog, "{ get_prev_frame (this_frame=");
1535 if (this_frame != NULL)
1536 fprintf_unfiltered (gdb_stdlog, "%d", this_frame->level);
1538 fprintf_unfiltered (gdb_stdlog, "<NULL>");
1539 fprintf_unfiltered (gdb_stdlog, ") -> // %s}\n", reason);
1543 /* Is this (non-sentinel) frame in the "main"() function? */
1546 inside_main_func (struct frame_info *this_frame)
1548 struct minimal_symbol *msymbol;
1551 if (symfile_objfile == 0)
1553 msymbol = lookup_minimal_symbol (main_name (), NULL, symfile_objfile);
1554 if (msymbol == NULL)
1556 /* Make certain that the code, and not descriptor, address is
1558 maddr = gdbarch_convert_from_func_ptr_addr (get_frame_arch (this_frame),
1559 SYMBOL_VALUE_ADDRESS (msymbol),
1561 return maddr == get_frame_func (this_frame);
1564 /* Test whether THIS_FRAME is inside the process entry point function. */
1567 inside_entry_func (struct frame_info *this_frame)
1569 return (get_frame_func (this_frame) == entry_point_address ());
1572 /* Return a structure containing various interesting information about
1573 the frame that called THIS_FRAME. Returns NULL if there is entier
1574 no such frame or the frame fails any of a set of target-independent
1575 condition that should terminate the frame chain (e.g., as unwinding
1578 This function should not contain target-dependent tests, such as
1579 checking whether the program-counter is zero. */
1582 get_prev_frame (struct frame_info *this_frame)
1584 struct frame_info *prev_frame;
1586 /* There is always a frame. If this assertion fails, suspect that
1587 something should be calling get_selected_frame() or
1588 get_current_frame(). */
1589 gdb_assert (this_frame != NULL);
1591 /* tausq/2004-12-07: Dummy frames are skipped because it doesn't make much
1592 sense to stop unwinding at a dummy frame. One place where a dummy
1593 frame may have an address "inside_main_func" is on HPUX. On HPUX, the
1594 pcsqh register (space register for the instruction at the head of the
1595 instruction queue) cannot be written directly; the only way to set it
1596 is to branch to code that is in the target space. In order to implement
1597 frame dummies on HPUX, the called function is made to jump back to where
1598 the inferior was when the user function was called. If gdb was inside
1599 the main function when we created the dummy frame, the dummy frame will
1600 point inside the main function. */
1601 if (this_frame->level >= 0
1602 && get_frame_type (this_frame) == NORMAL_FRAME
1603 && !backtrace_past_main
1604 && inside_main_func (this_frame))
1605 /* Don't unwind past main(). Note, this is done _before_ the
1606 frame has been marked as previously unwound. That way if the
1607 user later decides to enable unwinds past main(), that will
1608 automatically happen. */
1610 frame_debug_got_null_frame (this_frame, "inside main func");
1614 /* If the user's backtrace limit has been exceeded, stop. We must
1615 add two to the current level; one of those accounts for backtrace_limit
1616 being 1-based and the level being 0-based, and the other accounts for
1617 the level of the new frame instead of the level of the current
1619 if (this_frame->level + 2 > backtrace_limit)
1621 frame_debug_got_null_frame (this_frame, "backtrace limit exceeded");
1625 /* If we're already inside the entry function for the main objfile,
1626 then it isn't valid. Don't apply this test to a dummy frame -
1627 dummy frame PCs typically land in the entry func. Don't apply
1628 this test to the sentinel frame. Sentinel frames should always
1629 be allowed to unwind. */
1630 /* NOTE: cagney/2003-07-07: Fixed a bug in inside_main_func() -
1631 wasn't checking for "main" in the minimal symbols. With that
1632 fixed asm-source tests now stop in "main" instead of halting the
1633 backtrace in weird and wonderful ways somewhere inside the entry
1634 file. Suspect that tests for inside the entry file/func were
1635 added to work around that (now fixed) case. */
1636 /* NOTE: cagney/2003-07-15: danielj (if I'm reading it right)
1637 suggested having the inside_entry_func test use the
1638 inside_main_func() msymbol trick (along with entry_point_address()
1639 I guess) to determine the address range of the start function.
1640 That should provide a far better stopper than the current
1642 /* NOTE: tausq/2004-10-09: this is needed if, for example, the compiler
1643 applied tail-call optimizations to main so that a function called
1644 from main returns directly to the caller of main. Since we don't
1645 stop at main, we should at least stop at the entry point of the
1647 if (this_frame->level >= 0
1648 && get_frame_type (this_frame) == NORMAL_FRAME
1649 && !backtrace_past_entry
1650 && inside_entry_func (this_frame))
1652 frame_debug_got_null_frame (this_frame, "inside entry func");
1656 /* Assume that the only way to get a zero PC is through something
1657 like a SIGSEGV or a dummy frame, and hence that NORMAL frames
1658 will never unwind a zero PC. */
1659 if (this_frame->level > 0
1660 && (get_frame_type (this_frame) == NORMAL_FRAME
1661 || get_frame_type (this_frame) == INLINE_FRAME)
1662 && get_frame_type (get_next_frame (this_frame)) == NORMAL_FRAME
1663 && get_frame_pc (this_frame) == 0)
1665 frame_debug_got_null_frame (this_frame, "zero PC");
1669 return get_prev_frame_1 (this_frame);
1673 get_frame_pc (struct frame_info *frame)
1675 gdb_assert (frame->next != NULL);
1676 return frame_unwind_pc (frame->next);
1679 /* Return an address that falls within THIS_FRAME's code block. */
1682 get_frame_address_in_block (struct frame_info *this_frame)
1684 /* A draft address. */
1685 CORE_ADDR pc = get_frame_pc (this_frame);
1687 struct frame_info *next_frame = this_frame->next;
1689 /* Calling get_frame_pc returns the resume address for THIS_FRAME.
1690 Normally the resume address is inside the body of the function
1691 associated with THIS_FRAME, but there is a special case: when
1692 calling a function which the compiler knows will never return
1693 (for instance abort), the call may be the very last instruction
1694 in the calling function. The resume address will point after the
1695 call and may be at the beginning of a different function
1698 If THIS_FRAME is a signal frame or dummy frame, then we should
1699 not adjust the unwound PC. For a dummy frame, GDB pushed the
1700 resume address manually onto the stack. For a signal frame, the
1701 OS may have pushed the resume address manually and invoked the
1702 handler (e.g. GNU/Linux), or invoked the trampoline which called
1703 the signal handler - but in either case the signal handler is
1704 expected to return to the trampoline. So in both of these
1705 cases we know that the resume address is executable and
1706 related. So we only need to adjust the PC if THIS_FRAME
1707 is a normal function.
1709 If the program has been interrupted while THIS_FRAME is current,
1710 then clearly the resume address is inside the associated
1711 function. There are three kinds of interruption: debugger stop
1712 (next frame will be SENTINEL_FRAME), operating system
1713 signal or exception (next frame will be SIGTRAMP_FRAME),
1714 or debugger-induced function call (next frame will be
1715 DUMMY_FRAME). So we only need to adjust the PC if
1716 NEXT_FRAME is a normal function.
1718 We check the type of NEXT_FRAME first, since it is already
1719 known; frame type is determined by the unwinder, and since
1720 we have THIS_FRAME we've already selected an unwinder for
1723 If the next frame is inlined, we need to keep going until we find
1724 the real function - for instance, if a signal handler is invoked
1725 while in an inlined function, then the code address of the
1726 "calling" normal function should not be adjusted either. */
1728 while (get_frame_type (next_frame) == INLINE_FRAME)
1729 next_frame = next_frame->next;
1731 if (get_frame_type (next_frame) == NORMAL_FRAME
1732 && (get_frame_type (this_frame) == NORMAL_FRAME
1733 || get_frame_type (this_frame) == INLINE_FRAME))
1740 find_frame_sal (struct frame_info *frame, struct symtab_and_line *sal)
1742 struct frame_info *next_frame;
1745 /* If the next frame represents an inlined function call, this frame's
1746 sal is the "call site" of that inlined function, which can not
1747 be inferred from get_frame_pc. */
1748 next_frame = get_next_frame (frame);
1749 if (frame_inlined_callees (frame) > 0)
1754 sym = get_frame_function (next_frame);
1756 sym = inline_skipped_symbol (inferior_ptid);
1759 if (SYMBOL_LINE (sym) != 0)
1761 sal->symtab = SYMBOL_SYMTAB (sym);
1762 sal->line = SYMBOL_LINE (sym);
1765 /* If the symbol does not have a location, we don't know where
1766 the call site is. Do not pretend to. This is jarring, but
1767 we can't do much better. */
1768 sal->pc = get_frame_pc (frame);
1773 /* If FRAME is not the innermost frame, that normally means that
1774 FRAME->pc points at the return instruction (which is *after* the
1775 call instruction), and we want to get the line containing the
1776 call (because the call is where the user thinks the program is).
1777 However, if the next frame is either a SIGTRAMP_FRAME or a
1778 DUMMY_FRAME, then the next frame will contain a saved interrupt
1779 PC and such a PC indicates the current (rather than next)
1780 instruction/line, consequently, for such cases, want to get the
1781 line containing fi->pc. */
1782 notcurrent = (get_frame_pc (frame) != get_frame_address_in_block (frame));
1783 (*sal) = find_pc_line (get_frame_pc (frame), notcurrent);
1786 /* Per "frame.h", return the ``address'' of the frame. Code should
1787 really be using get_frame_id(). */
1789 get_frame_base (struct frame_info *fi)
1791 return get_frame_id (fi).stack_addr;
1794 /* High-level offsets into the frame. Used by the debug info. */
1797 get_frame_base_address (struct frame_info *fi)
1799 if (get_frame_type (fi) != NORMAL_FRAME)
1801 if (fi->base == NULL)
1802 fi->base = frame_base_find_by_frame (fi);
1803 /* Sneaky: If the low-level unwind and high-level base code share a
1804 common unwinder, let them share the prologue cache. */
1805 if (fi->base->unwind == fi->unwind)
1806 return fi->base->this_base (fi, &fi->prologue_cache);
1807 return fi->base->this_base (fi, &fi->base_cache);
1811 get_frame_locals_address (struct frame_info *fi)
1814 if (get_frame_type (fi) != NORMAL_FRAME)
1816 /* If there isn't a frame address method, find it. */
1817 if (fi->base == NULL)
1818 fi->base = frame_base_find_by_frame (fi);
1819 /* Sneaky: If the low-level unwind and high-level base code share a
1820 common unwinder, let them share the prologue cache. */
1821 if (fi->base->unwind == fi->unwind)
1822 return fi->base->this_locals (fi, &fi->prologue_cache);
1823 return fi->base->this_locals (fi, &fi->base_cache);
1827 get_frame_args_address (struct frame_info *fi)
1830 if (get_frame_type (fi) != NORMAL_FRAME)
1832 /* If there isn't a frame address method, find it. */
1833 if (fi->base == NULL)
1834 fi->base = frame_base_find_by_frame (fi);
1835 /* Sneaky: If the low-level unwind and high-level base code share a
1836 common unwinder, let them share the prologue cache. */
1837 if (fi->base->unwind == fi->unwind)
1838 return fi->base->this_args (fi, &fi->prologue_cache);
1839 return fi->base->this_args (fi, &fi->base_cache);
1842 /* Level of the selected frame: 0 for innermost, 1 for its caller, ...
1843 or -1 for a NULL frame. */
1846 frame_relative_level (struct frame_info *fi)
1855 get_frame_type (struct frame_info *frame)
1857 if (frame->unwind == NULL)
1858 /* Initialize the frame's unwinder because that's what
1859 provides the frame's type. */
1860 frame->unwind = frame_unwind_find_by_frame (frame, &frame->prologue_cache);
1861 return frame->unwind->type;
1864 /* Memory access methods. */
1867 get_frame_memory (struct frame_info *this_frame, CORE_ADDR addr,
1868 gdb_byte *buf, int len)
1870 read_memory (addr, buf, len);
1874 get_frame_memory_signed (struct frame_info *this_frame, CORE_ADDR addr,
1877 return read_memory_integer (addr, len);
1881 get_frame_memory_unsigned (struct frame_info *this_frame, CORE_ADDR addr,
1884 return read_memory_unsigned_integer (addr, len);
1888 safe_frame_unwind_memory (struct frame_info *this_frame,
1889 CORE_ADDR addr, gdb_byte *buf, int len)
1891 /* NOTE: target_read_memory returns zero on success! */
1892 return !target_read_memory (addr, buf, len);
1895 /* Architecture methods. */
1898 get_frame_arch (struct frame_info *this_frame)
1900 return frame_unwind_arch (this_frame->next);
1904 frame_unwind_arch (struct frame_info *next_frame)
1906 if (!next_frame->prev_arch.p)
1908 struct gdbarch *arch;
1910 if (next_frame->unwind == NULL)
1912 = frame_unwind_find_by_frame (next_frame,
1913 &next_frame->prologue_cache);
1915 if (next_frame->unwind->prev_arch != NULL)
1916 arch = next_frame->unwind->prev_arch (next_frame,
1917 &next_frame->prologue_cache);
1919 arch = get_frame_arch (next_frame);
1921 next_frame->prev_arch.arch = arch;
1922 next_frame->prev_arch.p = 1;
1924 fprintf_unfiltered (gdb_stdlog,
1925 "{ frame_unwind_arch (next_frame=%d) -> %s }\n",
1927 gdbarch_bfd_arch_info (arch)->printable_name);
1930 return next_frame->prev_arch.arch;
1934 frame_unwind_caller_arch (struct frame_info *next_frame)
1936 return frame_unwind_arch (skip_inlined_frames (next_frame));
1939 /* Stack pointer methods. */
1942 get_frame_sp (struct frame_info *this_frame)
1944 struct gdbarch *gdbarch = get_frame_arch (this_frame);
1945 /* Normality - an architecture that provides a way of obtaining any
1946 frame inner-most address. */
1947 if (gdbarch_unwind_sp_p (gdbarch))
1948 /* NOTE drow/2008-06-28: gdbarch_unwind_sp could be converted to
1949 operate on THIS_FRAME now. */
1950 return gdbarch_unwind_sp (gdbarch, this_frame->next);
1951 /* Now things are really are grim. Hope that the value returned by
1952 the gdbarch_sp_regnum register is meaningful. */
1953 if (gdbarch_sp_regnum (gdbarch) >= 0)
1954 return get_frame_register_unsigned (this_frame,
1955 gdbarch_sp_regnum (gdbarch));
1956 internal_error (__FILE__, __LINE__, _("Missing unwind SP method"));
1959 /* Return the reason why we can't unwind past FRAME. */
1961 enum unwind_stop_reason
1962 get_frame_unwind_stop_reason (struct frame_info *frame)
1964 /* If we haven't tried to unwind past this point yet, then assume
1965 that unwinding would succeed. */
1966 if (frame->prev_p == 0)
1967 return UNWIND_NO_REASON;
1969 /* Otherwise, we set a reason when we succeeded (or failed) to
1971 return frame->stop_reason;
1974 /* Return a string explaining REASON. */
1977 frame_stop_reason_string (enum unwind_stop_reason reason)
1981 case UNWIND_NULL_ID:
1982 return _("unwinder did not report frame ID");
1984 case UNWIND_INNER_ID:
1985 return _("previous frame inner to this frame (corrupt stack?)");
1987 case UNWIND_SAME_ID:
1988 return _("previous frame identical to this frame (corrupt stack?)");
1990 case UNWIND_NO_SAVED_PC:
1991 return _("frame did not save the PC");
1993 case UNWIND_NO_REASON:
1994 case UNWIND_FIRST_ERROR:
1996 internal_error (__FILE__, __LINE__,
1997 "Invalid frame stop reason");
2001 /* Clean up after a failed (wrong unwinder) attempt to unwind past
2005 frame_cleanup_after_sniffer (void *arg)
2007 struct frame_info *frame = arg;
2009 /* The sniffer should not allocate a prologue cache if it did not
2010 match this frame. */
2011 gdb_assert (frame->prologue_cache == NULL);
2013 /* No sniffer should extend the frame chain; sniff based on what is
2015 gdb_assert (!frame->prev_p);
2017 /* The sniffer should not check the frame's ID; that's circular. */
2018 gdb_assert (!frame->this_id.p);
2020 /* Clear cached fields dependent on the unwinder.
2022 The previous PC is independent of the unwinder, but the previous
2023 function is not (see get_frame_address_in_block). */
2024 frame->prev_func.p = 0;
2025 frame->prev_func.addr = 0;
2027 /* Discard the unwinder last, so that we can easily find it if an assertion
2028 in this function triggers. */
2029 frame->unwind = NULL;
2032 /* Set FRAME's unwinder temporarily, so that we can call a sniffer.
2033 Return a cleanup which should be called if unwinding fails, and
2034 discarded if it succeeds. */
2037 frame_prepare_for_sniffer (struct frame_info *frame,
2038 const struct frame_unwind *unwind)
2040 gdb_assert (frame->unwind == NULL);
2041 frame->unwind = unwind;
2042 return make_cleanup (frame_cleanup_after_sniffer, frame);
2045 extern initialize_file_ftype _initialize_frame; /* -Wmissing-prototypes */
2047 static struct cmd_list_element *set_backtrace_cmdlist;
2048 static struct cmd_list_element *show_backtrace_cmdlist;
2051 set_backtrace_cmd (char *args, int from_tty)
2053 help_list (set_backtrace_cmdlist, "set backtrace ", -1, gdb_stdout);
2057 show_backtrace_cmd (char *args, int from_tty)
2059 cmd_show_list (show_backtrace_cmdlist, from_tty, "");
2063 _initialize_frame (void)
2065 obstack_init (&frame_cache_obstack);
2067 observer_attach_target_changed (frame_observer_target_changed);
2069 add_prefix_cmd ("backtrace", class_maintenance, set_backtrace_cmd, _("\
2070 Set backtrace specific variables.\n\
2071 Configure backtrace variables such as the backtrace limit"),
2072 &set_backtrace_cmdlist, "set backtrace ",
2073 0/*allow-unknown*/, &setlist);
2074 add_prefix_cmd ("backtrace", class_maintenance, show_backtrace_cmd, _("\
2075 Show backtrace specific variables\n\
2076 Show backtrace variables such as the backtrace limit"),
2077 &show_backtrace_cmdlist, "show backtrace ",
2078 0/*allow-unknown*/, &showlist);
2080 add_setshow_boolean_cmd ("past-main", class_obscure,
2081 &backtrace_past_main, _("\
2082 Set whether backtraces should continue past \"main\"."), _("\
2083 Show whether backtraces should continue past \"main\"."), _("\
2084 Normally the caller of \"main\" is not of interest, so GDB will terminate\n\
2085 the backtrace at \"main\". Set this variable if you need to see the rest\n\
2086 of the stack trace."),
2088 show_backtrace_past_main,
2089 &set_backtrace_cmdlist,
2090 &show_backtrace_cmdlist);
2092 add_setshow_boolean_cmd ("past-entry", class_obscure,
2093 &backtrace_past_entry, _("\
2094 Set whether backtraces should continue past the entry point of a program."),
2096 Show whether backtraces should continue past the entry point of a program."),
2098 Normally there are no callers beyond the entry point of a program, so GDB\n\
2099 will terminate the backtrace there. Set this variable if you need to see \n\
2100 the rest of the stack trace."),
2102 show_backtrace_past_entry,
2103 &set_backtrace_cmdlist,
2104 &show_backtrace_cmdlist);
2106 add_setshow_integer_cmd ("limit", class_obscure,
2107 &backtrace_limit, _("\
2108 Set an upper bound on the number of backtrace levels."), _("\
2109 Show the upper bound on the number of backtrace levels."), _("\
2110 No more than the specified number of frames can be displayed or examined.\n\
2111 Zero is unlimited."),
2113 show_backtrace_limit,
2114 &set_backtrace_cmdlist,
2115 &show_backtrace_cmdlist);
2117 /* Debug this files internals. */
2118 add_setshow_zinteger_cmd ("frame", class_maintenance, &frame_debug, _("\
2119 Set frame debugging."), _("\
2120 Show frame debugging."), _("\
2121 When non-zero, frame specific internal debugging is enabled."),
2124 &setdebuglist, &showdebuglist);