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 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 static struct frame_info
*get_prev_frame_1 (struct frame_info
*this_frame
);
47 /* We keep a cache of stack frames, each of which is a "struct
48 frame_info". The innermost one gets allocated (in
49 wait_for_inferior) each time the inferior stops; current_frame
50 points to it. Additional frames get allocated (in get_prev_frame)
51 as needed, and are chained through the next and prev fields. Any
52 time that the frame cache becomes invalid (most notably when we
53 execute something, but also if we change how we interpret the
54 frames (e.g. "set heuristic-fence-post" in mips-tdep.c, or anything
55 which reads new symbols)), we should call reinit_frame_cache. */
59 /* Level of this frame. The inner-most (youngest) frame is at level
60 0. As you move towards the outer-most (oldest) frame, the level
61 increases. This is a cached value. It could just as easily be
62 computed by counting back from the selected frame to the inner
64 /* NOTE: cagney/2002-04-05: Perhaps a level of ``-1'' should be
65 reserved to indicate a bogus frame - one that has been created
66 just to keep GDB happy (GDB always needs a frame). For the
67 moment leave this as speculation. */
70 /* The frame's low-level unwinder and corresponding cache. The
71 low-level unwinder is responsible for unwinding register values
72 for the previous frame. The low-level unwind methods are
73 selected based on the presence, or otherwise, of register unwind
74 information such as CFI. */
76 const struct frame_unwind
*unwind
;
78 /* Cached copy of the previous frame's resume address. */
84 /* Cached copy of the previous frame's function address. */
91 /* This frame's ID. */
95 struct frame_id value
;
98 /* The frame's high-level base methods, and corresponding cache.
99 The high level base methods are selected based on the frame's
101 const struct frame_base
*base
;
104 /* Pointers to the next (down, inner, younger) and previous (up,
105 outer, older) frame_info's in the frame cache. */
106 struct frame_info
*next
; /* down, inner, younger */
108 struct frame_info
*prev
; /* up, outer, older */
110 /* The reason why we could not set PREV, or UNWIND_NO_REASON if we
111 could. Only valid when PREV_P is set. */
112 enum unwind_stop_reason stop_reason
;
115 /* Flag to control debugging. */
119 show_frame_debug (struct ui_file
*file
, int from_tty
,
120 struct cmd_list_element
*c
, const char *value
)
122 fprintf_filtered (file
, _("Frame debugging is %s.\n"), value
);
125 /* Flag to indicate whether backtraces should stop at main et.al. */
127 static int backtrace_past_main
;
129 show_backtrace_past_main (struct ui_file
*file
, int from_tty
,
130 struct cmd_list_element
*c
, const char *value
)
132 fprintf_filtered (file
, _("\
133 Whether backtraces should continue past \"main\" is %s.\n"),
137 static int backtrace_past_entry
;
139 show_backtrace_past_entry (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 the entry point of a program is %s.\n"),
147 static int backtrace_limit
= INT_MAX
;
149 show_backtrace_limit (struct ui_file
*file
, int from_tty
,
150 struct cmd_list_element
*c
, const char *value
)
152 fprintf_filtered (file
, _("\
153 An upper bound on the number of backtrace levels is %s.\n"),
159 fprint_field (struct ui_file
*file
, const char *name
, int p
, CORE_ADDR addr
)
162 fprintf_unfiltered (file
, "%s=0x%s", name
, paddr_nz (addr
));
164 fprintf_unfiltered (file
, "!%s", name
);
168 fprint_frame_id (struct ui_file
*file
, struct frame_id id
)
170 fprintf_unfiltered (file
, "{");
171 fprint_field (file
, "stack", id
.stack_addr_p
, id
.stack_addr
);
172 fprintf_unfiltered (file
, ",");
173 fprint_field (file
, "code", id
.code_addr_p
, id
.code_addr
);
174 fprintf_unfiltered (file
, ",");
175 fprint_field (file
, "special", id
.special_addr_p
, id
.special_addr
);
176 fprintf_unfiltered (file
, "}");
180 fprint_frame_type (struct ui_file
*file
, enum frame_type type
)
185 fprintf_unfiltered (file
, "NORMAL_FRAME");
188 fprintf_unfiltered (file
, "DUMMY_FRAME");
191 fprintf_unfiltered (file
, "SIGTRAMP_FRAME");
194 fprintf_unfiltered (file
, "<unknown type>");
200 fprint_frame (struct ui_file
*file
, struct frame_info
*fi
)
204 fprintf_unfiltered (file
, "<NULL frame>");
207 fprintf_unfiltered (file
, "{");
208 fprintf_unfiltered (file
, "level=%d", fi
->level
);
209 fprintf_unfiltered (file
, ",");
210 fprintf_unfiltered (file
, "type=");
211 if (fi
->unwind
!= NULL
)
212 fprint_frame_type (file
, fi
->unwind
->type
);
214 fprintf_unfiltered (file
, "<unknown>");
215 fprintf_unfiltered (file
, ",");
216 fprintf_unfiltered (file
, "unwind=");
217 if (fi
->unwind
!= NULL
)
218 gdb_print_host_address (fi
->unwind
, file
);
220 fprintf_unfiltered (file
, "<unknown>");
221 fprintf_unfiltered (file
, ",");
222 fprintf_unfiltered (file
, "pc=");
223 if (fi
->next
!= NULL
&& fi
->next
->prev_pc
.p
)
224 fprintf_unfiltered (file
, "0x%s", paddr_nz (fi
->next
->prev_pc
.value
));
226 fprintf_unfiltered (file
, "<unknown>");
227 fprintf_unfiltered (file
, ",");
228 fprintf_unfiltered (file
, "id=");
230 fprint_frame_id (file
, fi
->this_id
.value
);
232 fprintf_unfiltered (file
, "<unknown>");
233 fprintf_unfiltered (file
, ",");
234 fprintf_unfiltered (file
, "func=");
235 if (fi
->next
!= NULL
&& fi
->next
->prev_func
.p
)
236 fprintf_unfiltered (file
, "0x%s", paddr_nz (fi
->next
->prev_func
.addr
));
238 fprintf_unfiltered (file
, "<unknown>");
239 fprintf_unfiltered (file
, "}");
242 /* Return a frame uniq ID that can be used to, later, re-find the
246 get_frame_id (struct frame_info
*fi
)
250 return null_frame_id
;
255 fprintf_unfiltered (gdb_stdlog
, "{ get_frame_id (fi=%d) ",
257 /* Find the unwinder. */
258 if (fi
->unwind
== NULL
)
259 fi
->unwind
= frame_unwind_find_by_frame (fi
, &fi
->prologue_cache
);
260 /* Find THIS frame's ID. */
261 fi
->unwind
->this_id (fi
, &fi
->prologue_cache
, &fi
->this_id
.value
);
265 fprintf_unfiltered (gdb_stdlog
, "-> ");
266 fprint_frame_id (gdb_stdlog
, fi
->this_id
.value
);
267 fprintf_unfiltered (gdb_stdlog
, " }\n");
270 return fi
->this_id
.value
;
274 frame_unwind_id (struct frame_info
*next_frame
)
276 /* Use prev_frame, and not get_prev_frame. The latter will truncate
277 the frame chain, leading to this function unintentionally
278 returning a null_frame_id (e.g., when a caller requests the frame
279 ID of "main()"s caller. */
280 return get_frame_id (get_prev_frame_1 (next_frame
));
283 const struct frame_id null_frame_id
; /* All zeros. */
286 frame_id_build_special (CORE_ADDR stack_addr
, CORE_ADDR code_addr
,
287 CORE_ADDR special_addr
)
289 struct frame_id id
= null_frame_id
;
290 id
.stack_addr
= stack_addr
;
292 id
.code_addr
= code_addr
;
294 id
.special_addr
= special_addr
;
295 id
.special_addr_p
= 1;
300 frame_id_build (CORE_ADDR stack_addr
, CORE_ADDR code_addr
)
302 struct frame_id id
= null_frame_id
;
303 id
.stack_addr
= stack_addr
;
305 id
.code_addr
= code_addr
;
311 frame_id_build_wild (CORE_ADDR stack_addr
)
313 struct frame_id id
= null_frame_id
;
314 id
.stack_addr
= stack_addr
;
320 frame_id_p (struct frame_id l
)
323 /* The frame is valid iff it has a valid stack address. */
327 fprintf_unfiltered (gdb_stdlog
, "{ frame_id_p (l=");
328 fprint_frame_id (gdb_stdlog
, l
);
329 fprintf_unfiltered (gdb_stdlog
, ") -> %d }\n", p
);
335 frame_id_eq (struct frame_id l
, struct frame_id r
)
338 if (!l
.stack_addr_p
|| !r
.stack_addr_p
)
339 /* Like a NaN, if either ID is invalid, the result is false.
340 Note that a frame ID is invalid iff it is the null frame ID. */
342 else if (l
.stack_addr
!= r
.stack_addr
)
343 /* If .stack addresses are different, the frames are different. */
345 else if (!l
.code_addr_p
|| !r
.code_addr_p
)
346 /* An invalid code addr is a wild card, always succeed. */
348 else if (l
.code_addr
!= r
.code_addr
)
349 /* If .code addresses are different, the frames are different. */
351 else if (!l
.special_addr_p
|| !r
.special_addr_p
)
352 /* An invalid special addr is a wild card (or unused), always succeed. */
354 else if (l
.special_addr
== r
.special_addr
)
355 /* Frames are equal. */
362 fprintf_unfiltered (gdb_stdlog
, "{ frame_id_eq (l=");
363 fprint_frame_id (gdb_stdlog
, l
);
364 fprintf_unfiltered (gdb_stdlog
, ",r=");
365 fprint_frame_id (gdb_stdlog
, r
);
366 fprintf_unfiltered (gdb_stdlog
, ") -> %d }\n", eq
);
371 /* Safety net to check whether frame ID L should be inner to
372 frame ID R, according to their stack addresses.
374 This method cannot be used to compare arbitrary frames, as the
375 ranges of valid stack addresses may be discontiguous (e.g. due
378 However, it can be used as safety net to discover invalid frame
379 IDs in certain circumstances.
381 * If frame NEXT is the immediate inner frame to THIS, and NEXT
382 is a NORMAL frame, then the stack address of NEXT must be
383 inner-than-or-equal to the stack address of THIS.
385 Therefore, if frame_id_inner (THIS, NEXT) holds, some unwind
388 * If frame NEXT is the immediate inner frame to THIS, and NEXT
389 is a NORMAL frame, and NEXT and THIS have different stack
390 addresses, no other frame in the frame chain may have a stack
393 Therefore, if frame_id_inner (TEST, THIS) holds, but
394 frame_id_inner (TEST, NEXT) does not hold, TEST cannot refer
395 to a valid frame in the frame chain. */
398 frame_id_inner (struct gdbarch
*gdbarch
, struct frame_id l
, struct frame_id r
)
401 if (!l
.stack_addr_p
|| !r
.stack_addr_p
)
402 /* Like NaN, any operation involving an invalid ID always fails. */
405 /* Only return non-zero when strictly inner than. Note that, per
406 comment in "frame.h", there is some fuzz here. Frameless
407 functions are not strictly inner than (same .stack but
408 different .code and/or .special address). */
409 inner
= gdbarch_inner_than (gdbarch
, l
.stack_addr
, r
.stack_addr
);
412 fprintf_unfiltered (gdb_stdlog
, "{ frame_id_inner (l=");
413 fprint_frame_id (gdb_stdlog
, l
);
414 fprintf_unfiltered (gdb_stdlog
, ",r=");
415 fprint_frame_id (gdb_stdlog
, r
);
416 fprintf_unfiltered (gdb_stdlog
, ") -> %d }\n", inner
);
422 frame_find_by_id (struct frame_id id
)
424 struct frame_info
*frame
, *prev_frame
;
426 /* ZERO denotes the null frame, let the caller decide what to do
427 about it. Should it instead return get_current_frame()? */
428 if (!frame_id_p (id
))
431 for (frame
= get_current_frame (); ; frame
= prev_frame
)
433 struct frame_id
this = get_frame_id (frame
);
434 if (frame_id_eq (id
, this))
435 /* An exact match. */
438 prev_frame
= get_prev_frame (frame
);
442 /* As a safety net to avoid unnecessary backtracing while trying
443 to find an invalid ID, we check for a common situation where
444 we can detect from comparing stack addresses that no other
445 frame in the current frame chain can have this ID. See the
446 comment at frame_id_inner for details. */
447 if (get_frame_type (frame
) == NORMAL_FRAME
448 && !frame_id_inner (get_frame_arch (frame
), id
, this)
449 && frame_id_inner (get_frame_arch (prev_frame
), id
,
450 get_frame_id (prev_frame
)))
457 frame_pc_unwind (struct frame_info
*this_frame
)
459 if (!this_frame
->prev_pc
.p
)
462 if (gdbarch_unwind_pc_p (get_frame_arch (this_frame
)))
464 /* The right way. The `pure' way. The one true way. This
465 method depends solely on the register-unwind code to
466 determine the value of registers in THIS frame, and hence
467 the value of this frame's PC (resume address). A typical
468 implementation is no more than:
470 frame_unwind_register (this_frame, ISA_PC_REGNUM, buf);
471 return extract_unsigned_integer (buf, size of ISA_PC_REGNUM);
473 Note: this method is very heavily dependent on a correct
474 register-unwind implementation, it pays to fix that
475 method first; this method is frame type agnostic, since
476 it only deals with register values, it works with any
477 frame. This is all in stark contrast to the old
478 FRAME_SAVED_PC which would try to directly handle all the
479 different ways that a PC could be unwound. */
480 pc
= gdbarch_unwind_pc (get_frame_arch (this_frame
), this_frame
);
483 internal_error (__FILE__
, __LINE__
, _("No unwind_pc method"));
484 this_frame
->prev_pc
.value
= pc
;
485 this_frame
->prev_pc
.p
= 1;
487 fprintf_unfiltered (gdb_stdlog
,
488 "{ frame_pc_unwind (this_frame=%d) -> 0x%s }\n",
490 paddr_nz (this_frame
->prev_pc
.value
));
492 return this_frame
->prev_pc
.value
;
496 get_frame_func (struct frame_info
*this_frame
)
498 struct frame_info
*next_frame
= this_frame
->next
;
500 if (!next_frame
->prev_func
.p
)
502 /* Make certain that this, and not the adjacent, function is
504 CORE_ADDR addr_in_block
= get_frame_address_in_block (this_frame
);
505 next_frame
->prev_func
.p
= 1;
506 next_frame
->prev_func
.addr
= get_pc_function_start (addr_in_block
);
508 fprintf_unfiltered (gdb_stdlog
,
509 "{ get_frame_func (this_frame=%d) -> 0x%s }\n",
511 paddr_nz (next_frame
->prev_func
.addr
));
513 return next_frame
->prev_func
.addr
;
517 do_frame_register_read (void *src
, int regnum
, gdb_byte
*buf
)
519 return frame_register_read (src
, regnum
, buf
);
523 frame_save_as_regcache (struct frame_info
*this_frame
)
525 struct regcache
*regcache
= regcache_xmalloc (get_frame_arch (this_frame
));
526 struct cleanup
*cleanups
= make_cleanup_regcache_xfree (regcache
);
527 regcache_save (regcache
, do_frame_register_read
, this_frame
);
528 discard_cleanups (cleanups
);
533 frame_pop (struct frame_info
*this_frame
)
535 struct frame_info
*prev_frame
;
536 struct regcache
*scratch
;
537 struct cleanup
*cleanups
;
539 /* Ensure that we have a frame to pop to. */
540 prev_frame
= get_prev_frame_1 (this_frame
);
543 error (_("Cannot pop the initial frame."));
545 /* Make a copy of all the register values unwound from this frame.
546 Save them in a scratch buffer so that there isn't a race between
547 trying to extract the old values from the current regcache while
548 at the same time writing new values into that same cache. */
549 scratch
= frame_save_as_regcache (prev_frame
);
550 cleanups
= make_cleanup_regcache_xfree (scratch
);
552 /* If we are popping a dummy frame, clean up the associated
554 if (get_frame_type (this_frame
) == DUMMY_FRAME
)
555 dummy_frame_pop (get_frame_id (this_frame
));
557 /* FIXME: cagney/2003-03-16: It should be possible to tell the
558 target's register cache that it is about to be hit with a burst
559 register transfer and that the sequence of register writes should
560 be batched. The pair target_prepare_to_store() and
561 target_store_registers() kind of suggest this functionality.
562 Unfortunately, they don't implement it. Their lack of a formal
563 definition can lead to targets writing back bogus values
564 (arguably a bug in the target code mind). */
565 /* Now copy those saved registers into the current regcache.
566 Here, regcache_cpy() calls regcache_restore(). */
567 regcache_cpy (get_current_regcache (), scratch
);
568 do_cleanups (cleanups
);
570 /* We've made right mess of GDB's local state, just discard
572 reinit_frame_cache ();
576 frame_register_unwind (struct frame_info
*frame
, int regnum
,
577 int *optimizedp
, enum lval_type
*lvalp
,
578 CORE_ADDR
*addrp
, int *realnump
, gdb_byte
*bufferp
)
582 /* Require all but BUFFERP to be valid. A NULL BUFFERP indicates
583 that the value proper does not need to be fetched. */
584 gdb_assert (optimizedp
!= NULL
);
585 gdb_assert (lvalp
!= NULL
);
586 gdb_assert (addrp
!= NULL
);
587 gdb_assert (realnump
!= NULL
);
588 /* gdb_assert (bufferp != NULL); */
590 value
= frame_unwind_register_value (frame
, regnum
);
592 gdb_assert (value
!= NULL
);
594 *optimizedp
= value_optimized_out (value
);
595 *lvalp
= VALUE_LVAL (value
);
596 *addrp
= VALUE_ADDRESS (value
);
597 *realnump
= VALUE_REGNUM (value
);
600 memcpy (bufferp
, value_contents_all (value
),
601 TYPE_LENGTH (value_type (value
)));
603 /* Dispose of the new value. This prevents watchpoints from
604 trying to watch the saved frame pointer. */
605 release_value (value
);
610 frame_register (struct frame_info
*frame
, int regnum
,
611 int *optimizedp
, enum lval_type
*lvalp
,
612 CORE_ADDR
*addrp
, int *realnump
, gdb_byte
*bufferp
)
614 /* Require all but BUFFERP to be valid. A NULL BUFFERP indicates
615 that the value proper does not need to be fetched. */
616 gdb_assert (optimizedp
!= NULL
);
617 gdb_assert (lvalp
!= NULL
);
618 gdb_assert (addrp
!= NULL
);
619 gdb_assert (realnump
!= NULL
);
620 /* gdb_assert (bufferp != NULL); */
622 /* Obtain the register value by unwinding the register from the next
623 (more inner frame). */
624 gdb_assert (frame
!= NULL
&& frame
->next
!= NULL
);
625 frame_register_unwind (frame
->next
, regnum
, optimizedp
, lvalp
, addrp
,
630 frame_unwind_register (struct frame_info
*frame
, int regnum
, gdb_byte
*buf
)
636 frame_register_unwind (frame
, regnum
, &optimized
, &lval
, &addr
,
641 get_frame_register (struct frame_info
*frame
,
642 int regnum
, gdb_byte
*buf
)
644 frame_unwind_register (frame
->next
, regnum
, buf
);
648 frame_unwind_register_value (struct frame_info
*frame
, int regnum
)
652 gdb_assert (frame
!= NULL
);
656 fprintf_unfiltered (gdb_stdlog
, "\
657 { frame_unwind_register_value (frame=%d,regnum=%d(%s),...) ",
658 frame
->level
, regnum
,
659 user_reg_map_regnum_to_name
660 (get_frame_arch (frame
), regnum
));
663 /* Find the unwinder. */
664 if (frame
->unwind
== NULL
)
665 frame
->unwind
= frame_unwind_find_by_frame (frame
, &frame
->prologue_cache
);
667 /* Ask this frame to unwind its register. */
668 value
= frame
->unwind
->prev_register (frame
, &frame
->prologue_cache
, regnum
);
672 fprintf_unfiltered (gdb_stdlog
, "->");
673 if (value_optimized_out (value
))
674 fprintf_unfiltered (gdb_stdlog
, " optimized out");
677 if (VALUE_LVAL (value
) == lval_register
)
678 fprintf_unfiltered (gdb_stdlog
, " register=%d",
679 VALUE_REGNUM (value
));
680 else if (VALUE_LVAL (value
) == lval_memory
)
681 fprintf_unfiltered (gdb_stdlog
, " address=0x%s",
682 paddr_nz (VALUE_ADDRESS (value
)));
684 fprintf_unfiltered (gdb_stdlog
, " computed");
686 if (value_lazy (value
))
687 fprintf_unfiltered (gdb_stdlog
, " lazy");
691 const gdb_byte
*buf
= value_contents (value
);
693 fprintf_unfiltered (gdb_stdlog
, " bytes=");
694 fprintf_unfiltered (gdb_stdlog
, "[");
695 for (i
= 0; i
< register_size (get_frame_arch (frame
), regnum
); i
++)
696 fprintf_unfiltered (gdb_stdlog
, "%02x", buf
[i
]);
697 fprintf_unfiltered (gdb_stdlog
, "]");
701 fprintf_unfiltered (gdb_stdlog
, " }\n");
708 get_frame_register_value (struct frame_info
*frame
, int regnum
)
710 return frame_unwind_register_value (frame
->next
, regnum
);
714 frame_unwind_register_signed (struct frame_info
*frame
, int regnum
)
716 gdb_byte buf
[MAX_REGISTER_SIZE
];
717 frame_unwind_register (frame
, regnum
, buf
);
718 return extract_signed_integer (buf
, register_size (get_frame_arch (frame
),
723 get_frame_register_signed (struct frame_info
*frame
, int regnum
)
725 return frame_unwind_register_signed (frame
->next
, regnum
);
729 frame_unwind_register_unsigned (struct frame_info
*frame
, int regnum
)
731 gdb_byte buf
[MAX_REGISTER_SIZE
];
732 frame_unwind_register (frame
, regnum
, buf
);
733 return extract_unsigned_integer (buf
, register_size (get_frame_arch (frame
),
738 get_frame_register_unsigned (struct frame_info
*frame
, int regnum
)
740 return frame_unwind_register_unsigned (frame
->next
, regnum
);
744 put_frame_register (struct frame_info
*frame
, int regnum
,
747 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
752 frame_register (frame
, regnum
, &optim
, &lval
, &addr
, &realnum
, NULL
);
754 error (_("Attempt to assign to a value that was optimized out."));
759 /* FIXME: write_memory doesn't yet take constant buffers.
761 gdb_byte tmp
[MAX_REGISTER_SIZE
];
762 memcpy (tmp
, buf
, register_size (gdbarch
, regnum
));
763 write_memory (addr
, tmp
, register_size (gdbarch
, regnum
));
767 regcache_cooked_write (get_current_regcache (), realnum
, buf
);
770 error (_("Attempt to assign to an unmodifiable value."));
774 /* frame_register_read ()
776 Find and return the value of REGNUM for the specified stack frame.
777 The number of bytes copied is REGISTER_SIZE (REGNUM).
779 Returns 0 if the register value could not be found. */
782 frame_register_read (struct frame_info
*frame
, int regnum
,
789 frame_register (frame
, regnum
, &optimized
, &lval
, &addr
, &realnum
, myaddr
);
795 get_frame_register_bytes (struct frame_info
*frame
, int regnum
,
796 CORE_ADDR offset
, int len
, gdb_byte
*myaddr
)
798 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
802 /* Skip registers wholly inside of OFFSET. */
803 while (offset
>= register_size (gdbarch
, regnum
))
805 offset
-= register_size (gdbarch
, regnum
);
809 /* Detect bad debug info. */
811 for (i
= regnum
; i
< gdbarch_num_regs (gdbarch
); i
++)
813 int thissize
= register_size (gdbarch
, i
);
820 warning (_("Bad debug information detected: "
821 "Attempt to read %d bytes from registers."), len
);
828 int curr_len
= register_size (gdbarch
, regnum
) - offset
;
832 if (curr_len
== register_size (gdbarch
, regnum
))
834 if (!frame_register_read (frame
, regnum
, myaddr
))
839 gdb_byte buf
[MAX_REGISTER_SIZE
];
840 if (!frame_register_read (frame
, regnum
, buf
))
842 memcpy (myaddr
, buf
+ offset
, curr_len
);
855 put_frame_register_bytes (struct frame_info
*frame
, int regnum
,
856 CORE_ADDR offset
, int len
, const gdb_byte
*myaddr
)
858 struct gdbarch
*gdbarch
= get_frame_arch (frame
);
860 /* Skip registers wholly inside of OFFSET. */
861 while (offset
>= register_size (gdbarch
, regnum
))
863 offset
-= register_size (gdbarch
, regnum
);
870 int curr_len
= register_size (gdbarch
, regnum
) - offset
;
874 if (curr_len
== register_size (gdbarch
, regnum
))
876 put_frame_register (frame
, regnum
, myaddr
);
880 gdb_byte buf
[MAX_REGISTER_SIZE
];
881 frame_register_read (frame
, regnum
, buf
);
882 memcpy (buf
+ offset
, myaddr
, curr_len
);
883 put_frame_register (frame
, regnum
, buf
);
893 /* Create a sentinel frame. */
895 static struct frame_info
*
896 create_sentinel_frame (struct regcache
*regcache
)
898 struct frame_info
*frame
= FRAME_OBSTACK_ZALLOC (struct frame_info
);
900 /* Explicitly initialize the sentinel frame's cache. Provide it
901 with the underlying regcache. In the future additional
902 information, such as the frame's thread will be added. */
903 frame
->prologue_cache
= sentinel_frame_cache (regcache
);
904 /* For the moment there is only one sentinel frame implementation. */
905 frame
->unwind
= sentinel_frame_unwind
;
906 /* Link this frame back to itself. The frame is self referential
907 (the unwound PC is the same as the pc), so make it so. */
909 /* Make the sentinel frame's ID valid, but invalid. That way all
910 comparisons with it should fail. */
911 frame
->this_id
.p
= 1;
912 frame
->this_id
.value
= null_frame_id
;
915 fprintf_unfiltered (gdb_stdlog
, "{ create_sentinel_frame (...) -> ");
916 fprint_frame (gdb_stdlog
, frame
);
917 fprintf_unfiltered (gdb_stdlog
, " }\n");
922 /* Info about the innermost stack frame (contents of FP register) */
924 static struct frame_info
*current_frame
;
926 /* Cache for frame addresses already read by gdb. Valid only while
927 inferior is stopped. Control variables for the frame cache should
928 be local to this module. */
930 static struct obstack frame_cache_obstack
;
933 frame_obstack_zalloc (unsigned long size
)
935 void *data
= obstack_alloc (&frame_cache_obstack
, size
);
936 memset (data
, 0, size
);
940 /* Return the innermost (currently executing) stack frame. This is
941 split into two functions. The function unwind_to_current_frame()
942 is wrapped in catch exceptions so that, even when the unwind of the
943 sentinel frame fails, the function still returns a stack frame. */
946 unwind_to_current_frame (struct ui_out
*ui_out
, void *args
)
948 struct frame_info
*frame
= get_prev_frame (args
);
949 /* A sentinel frame can fail to unwind, e.g., because its PC value
950 lands in somewhere like start. */
953 current_frame
= frame
;
958 get_current_frame (void)
960 /* First check, and report, the lack of registers. Having GDB
961 report "No stack!" or "No memory" when the target doesn't even
962 have registers is very confusing. Besides, "printcmd.exp"
963 explicitly checks that ``print $pc'' with no registers prints "No
965 if (!target_has_registers
)
966 error (_("No registers."));
967 if (!target_has_stack
)
968 error (_("No stack."));
969 if (!target_has_memory
)
970 error (_("No memory."));
971 if (is_executing (inferior_ptid
))
972 error (_("Target is executing."));
974 if (current_frame
== NULL
)
976 struct frame_info
*sentinel_frame
=
977 create_sentinel_frame (get_current_regcache ());
978 if (catch_exceptions (uiout
, unwind_to_current_frame
, sentinel_frame
,
979 RETURN_MASK_ERROR
) != 0)
981 /* Oops! Fake a current frame? Is this useful? It has a PC
982 of zero, for instance. */
983 current_frame
= sentinel_frame
;
986 return current_frame
;
989 /* The "selected" stack frame is used by default for local and arg
990 access. May be zero, for no selected frame. */
992 static struct frame_info
*selected_frame
;
995 has_stack_frames (void)
997 if (!target_has_registers
|| !target_has_stack
|| !target_has_memory
)
1000 /* If the current thread is executing, don't try to read from
1002 if (is_executing (inferior_ptid
))
1008 /* Return the selected frame. Always non-NULL (unless there isn't an
1009 inferior sufficient for creating a frame) in which case an error is
1013 get_selected_frame (const char *message
)
1015 if (selected_frame
== NULL
)
1017 if (message
!= NULL
&& !has_stack_frames ())
1018 error (("%s"), message
);
1019 /* Hey! Don't trust this. It should really be re-finding the
1020 last selected frame of the currently selected thread. This,
1021 though, is better than nothing. */
1022 select_frame (get_current_frame ());
1024 /* There is always a frame. */
1025 gdb_assert (selected_frame
!= NULL
);
1026 return selected_frame
;
1029 /* This is a variant of get_selected_frame() which can be called when
1030 the inferior does not have a frame; in that case it will return
1031 NULL instead of calling error(). */
1034 deprecated_safe_get_selected_frame (void)
1036 if (!has_stack_frames ())
1038 return get_selected_frame (NULL
);
1041 /* Select frame FI (or NULL - to invalidate the current frame). */
1044 select_frame (struct frame_info
*fi
)
1048 selected_frame
= fi
;
1049 /* NOTE: cagney/2002-05-04: FI can be NULL. This occurs when the
1050 frame is being invalidated. */
1051 if (deprecated_selected_frame_level_changed_hook
)
1052 deprecated_selected_frame_level_changed_hook (frame_relative_level (fi
));
1054 /* FIXME: kseitz/2002-08-28: It would be nice to call
1055 selected_frame_level_changed_event() right here, but due to limitations
1056 in the current interfaces, we would end up flooding UIs with events
1057 because select_frame() is used extensively internally.
1059 Once we have frame-parameterized frame (and frame-related) commands,
1060 the event notification can be moved here, since this function will only
1061 be called when the user's selected frame is being changed. */
1063 /* Ensure that symbols for this frame are read in. Also, determine the
1064 source language of this frame, and switch to it if desired. */
1067 /* We retrieve the frame's symtab by using the frame PC. However
1068 we cannot use the frame PC as-is, because it usually points to
1069 the instruction following the "call", which is sometimes the
1070 first instruction of another function. So we rely on
1071 get_frame_address_in_block() which provides us with a PC which
1072 is guaranteed to be inside the frame's code block. */
1073 s
= find_pc_symtab (get_frame_address_in_block (fi
));
1075 && s
->language
!= current_language
->la_language
1076 && s
->language
!= language_unknown
1077 && language_mode
== language_mode_auto
)
1079 set_language (s
->language
);
1084 /* Create an arbitrary (i.e. address specified by user) or innermost frame.
1085 Always returns a non-NULL value. */
1088 create_new_frame (CORE_ADDR addr
, CORE_ADDR pc
)
1090 struct frame_info
*fi
;
1094 fprintf_unfiltered (gdb_stdlog
,
1095 "{ create_new_frame (addr=0x%s, pc=0x%s) ",
1096 paddr_nz (addr
), paddr_nz (pc
));
1099 fi
= FRAME_OBSTACK_ZALLOC (struct frame_info
);
1101 fi
->next
= create_sentinel_frame (get_current_regcache ());
1103 /* Select/initialize both the unwind function and the frame's type
1105 fi
->unwind
= frame_unwind_find_by_frame (fi
, &fi
->prologue_cache
);
1108 deprecated_update_frame_base_hack (fi
, addr
);
1109 deprecated_update_frame_pc_hack (fi
, pc
);
1113 fprintf_unfiltered (gdb_stdlog
, "-> ");
1114 fprint_frame (gdb_stdlog
, fi
);
1115 fprintf_unfiltered (gdb_stdlog
, " }\n");
1121 /* Return the frame that THIS_FRAME calls (NULL if THIS_FRAME is the
1122 innermost frame). Be careful to not fall off the bottom of the
1123 frame chain and onto the sentinel frame. */
1126 get_next_frame (struct frame_info
*this_frame
)
1128 if (this_frame
->level
> 0)
1129 return this_frame
->next
;
1134 /* Observer for the target_changed event. */
1137 frame_observer_target_changed (struct target_ops
*target
)
1139 reinit_frame_cache ();
1142 /* Flush the entire frame cache. */
1145 reinit_frame_cache (void)
1147 struct frame_info
*fi
;
1149 /* Tear down all frame caches. */
1150 for (fi
= current_frame
; fi
!= NULL
; fi
= fi
->prev
)
1152 if (fi
->prologue_cache
&& fi
->unwind
->dealloc_cache
)
1153 fi
->unwind
->dealloc_cache (fi
, fi
->prologue_cache
);
1154 if (fi
->base_cache
&& fi
->base
->unwind
->dealloc_cache
)
1155 fi
->base
->unwind
->dealloc_cache (fi
, fi
->base_cache
);
1158 /* Since we can't really be sure what the first object allocated was */
1159 obstack_free (&frame_cache_obstack
, 0);
1160 obstack_init (&frame_cache_obstack
);
1162 if (current_frame
!= NULL
)
1163 annotate_frames_invalid ();
1165 current_frame
= NULL
; /* Invalidate cache */
1166 select_frame (NULL
);
1168 fprintf_unfiltered (gdb_stdlog
, "{ reinit_frame_cache () }\n");
1171 /* Find where a register is saved (in memory or another register).
1172 The result of frame_register_unwind is just where it is saved
1173 relative to this particular frame. */
1176 frame_register_unwind_location (struct frame_info
*this_frame
, int regnum
,
1177 int *optimizedp
, enum lval_type
*lvalp
,
1178 CORE_ADDR
*addrp
, int *realnump
)
1180 gdb_assert (this_frame
== NULL
|| this_frame
->level
>= 0);
1182 while (this_frame
!= NULL
)
1184 frame_register_unwind (this_frame
, regnum
, optimizedp
, lvalp
,
1185 addrp
, realnump
, NULL
);
1190 if (*lvalp
!= lval_register
)
1194 this_frame
= get_next_frame (this_frame
);
1198 /* Return a "struct frame_info" corresponding to the frame that called
1199 THIS_FRAME. Returns NULL if there is no such frame.
1201 Unlike get_prev_frame, this function always tries to unwind the
1204 static struct frame_info
*
1205 get_prev_frame_1 (struct frame_info
*this_frame
)
1207 struct frame_info
*prev_frame
;
1208 struct frame_id this_id
;
1209 struct gdbarch
*gdbarch
;
1211 gdb_assert (this_frame
!= NULL
);
1212 gdbarch
= get_frame_arch (this_frame
);
1216 fprintf_unfiltered (gdb_stdlog
, "{ get_prev_frame_1 (this_frame=");
1217 if (this_frame
!= NULL
)
1218 fprintf_unfiltered (gdb_stdlog
, "%d", this_frame
->level
);
1220 fprintf_unfiltered (gdb_stdlog
, "<NULL>");
1221 fprintf_unfiltered (gdb_stdlog
, ") ");
1224 /* Only try to do the unwind once. */
1225 if (this_frame
->prev_p
)
1229 fprintf_unfiltered (gdb_stdlog
, "-> ");
1230 fprint_frame (gdb_stdlog
, this_frame
->prev
);
1231 fprintf_unfiltered (gdb_stdlog
, " // cached \n");
1233 return this_frame
->prev
;
1236 /* If the frame unwinder hasn't been selected yet, we must do so
1237 before setting prev_p; otherwise the check for misbehaved
1238 sniffers will think that this frame's sniffer tried to unwind
1239 further (see frame_cleanup_after_sniffer). */
1240 if (this_frame
->unwind
== NULL
)
1242 = frame_unwind_find_by_frame (this_frame
, &this_frame
->prologue_cache
);
1244 this_frame
->prev_p
= 1;
1245 this_frame
->stop_reason
= UNWIND_NO_REASON
;
1247 /* Check that this frame's ID was valid. If it wasn't, don't try to
1248 unwind to the prev frame. Be careful to not apply this test to
1249 the sentinel frame. */
1250 this_id
= get_frame_id (this_frame
);
1251 if (this_frame
->level
>= 0 && !frame_id_p (this_id
))
1255 fprintf_unfiltered (gdb_stdlog
, "-> ");
1256 fprint_frame (gdb_stdlog
, NULL
);
1257 fprintf_unfiltered (gdb_stdlog
, " // this ID is NULL }\n");
1259 this_frame
->stop_reason
= UNWIND_NULL_ID
;
1263 /* Check that this frame's ID isn't inner to (younger, below, next)
1264 the next frame. This happens when a frame unwind goes backwards.
1265 This check is valid only if the next frame is NORMAL. See the
1266 comment at frame_id_inner for details. */
1267 if (this_frame
->next
->unwind
->type
== NORMAL_FRAME
1268 && frame_id_inner (get_frame_arch (this_frame
->next
), this_id
,
1269 get_frame_id (this_frame
->next
)))
1273 fprintf_unfiltered (gdb_stdlog
, "-> ");
1274 fprint_frame (gdb_stdlog
, NULL
);
1275 fprintf_unfiltered (gdb_stdlog
, " // this frame ID is inner }\n");
1277 this_frame
->stop_reason
= UNWIND_INNER_ID
;
1281 /* Check that this and the next frame are not identical. If they
1282 are, there is most likely a stack cycle. As with the inner-than
1283 test above, avoid comparing the inner-most and sentinel frames. */
1284 if (this_frame
->level
> 0
1285 && frame_id_eq (this_id
, get_frame_id (this_frame
->next
)))
1289 fprintf_unfiltered (gdb_stdlog
, "-> ");
1290 fprint_frame (gdb_stdlog
, NULL
);
1291 fprintf_unfiltered (gdb_stdlog
, " // this frame has same ID }\n");
1293 this_frame
->stop_reason
= UNWIND_SAME_ID
;
1297 /* Check that this and the next frame do not unwind the PC register
1298 to the same memory location. If they do, then even though they
1299 have different frame IDs, the new frame will be bogus; two
1300 functions can't share a register save slot for the PC. This can
1301 happen when the prologue analyzer finds a stack adjustment, but
1304 This check does assume that the "PC register" is roughly a
1305 traditional PC, even if the gdbarch_unwind_pc method adjusts
1306 it (we do not rely on the value, only on the unwound PC being
1307 dependent on this value). A potential improvement would be
1308 to have the frame prev_pc method and the gdbarch unwind_pc
1309 method set the same lval and location information as
1310 frame_register_unwind. */
1311 if (this_frame
->level
> 0
1312 && gdbarch_pc_regnum (gdbarch
) >= 0
1313 && get_frame_type (this_frame
) == NORMAL_FRAME
1314 && get_frame_type (this_frame
->next
) == NORMAL_FRAME
)
1316 int optimized
, realnum
, nrealnum
;
1317 enum lval_type lval
, nlval
;
1318 CORE_ADDR addr
, naddr
;
1320 frame_register_unwind_location (this_frame
,
1321 gdbarch_pc_regnum (gdbarch
),
1322 &optimized
, &lval
, &addr
, &realnum
);
1323 frame_register_unwind_location (get_next_frame (this_frame
),
1324 gdbarch_pc_regnum (gdbarch
),
1325 &optimized
, &nlval
, &naddr
, &nrealnum
);
1327 if ((lval
== lval_memory
&& lval
== nlval
&& addr
== naddr
)
1328 || (lval
== lval_register
&& lval
== nlval
&& realnum
== nrealnum
))
1332 fprintf_unfiltered (gdb_stdlog
, "-> ");
1333 fprint_frame (gdb_stdlog
, NULL
);
1334 fprintf_unfiltered (gdb_stdlog
, " // no saved PC }\n");
1337 this_frame
->stop_reason
= UNWIND_NO_SAVED_PC
;
1338 this_frame
->prev
= NULL
;
1343 /* Allocate the new frame but do not wire it in to the frame chain.
1344 Some (bad) code in INIT_FRAME_EXTRA_INFO tries to look along
1345 frame->next to pull some fancy tricks (of course such code is, by
1346 definition, recursive). Try to prevent it.
1348 There is no reason to worry about memory leaks, should the
1349 remainder of the function fail. The allocated memory will be
1350 quickly reclaimed when the frame cache is flushed, and the `we've
1351 been here before' check above will stop repeated memory
1352 allocation calls. */
1353 prev_frame
= FRAME_OBSTACK_ZALLOC (struct frame_info
);
1354 prev_frame
->level
= this_frame
->level
+ 1;
1356 /* Don't yet compute ->unwind (and hence ->type). It is computed
1357 on-demand in get_frame_type, frame_register_unwind, and
1360 /* Don't yet compute the frame's ID. It is computed on-demand by
1363 /* The unwound frame ID is validate at the start of this function,
1364 as part of the logic to decide if that frame should be further
1365 unwound, and not here while the prev frame is being created.
1366 Doing this makes it possible for the user to examine a frame that
1367 has an invalid frame ID.
1369 Some very old VAX code noted: [...] For the sake of argument,
1370 suppose that the stack is somewhat trashed (which is one reason
1371 that "info frame" exists). So, return 0 (indicating we don't
1372 know the address of the arglist) if we don't know what frame this
1376 this_frame
->prev
= prev_frame
;
1377 prev_frame
->next
= this_frame
;
1381 fprintf_unfiltered (gdb_stdlog
, "-> ");
1382 fprint_frame (gdb_stdlog
, prev_frame
);
1383 fprintf_unfiltered (gdb_stdlog
, " }\n");
1389 /* Debug routine to print a NULL frame being returned. */
1392 frame_debug_got_null_frame (struct ui_file
*file
,
1393 struct frame_info
*this_frame
,
1398 fprintf_unfiltered (gdb_stdlog
, "{ get_prev_frame (this_frame=");
1399 if (this_frame
!= NULL
)
1400 fprintf_unfiltered (gdb_stdlog
, "%d", this_frame
->level
);
1402 fprintf_unfiltered (gdb_stdlog
, "<NULL>");
1403 fprintf_unfiltered (gdb_stdlog
, ") -> // %s}\n", reason
);
1407 /* Is this (non-sentinel) frame in the "main"() function? */
1410 inside_main_func (struct frame_info
*this_frame
)
1412 struct minimal_symbol
*msymbol
;
1415 if (symfile_objfile
== 0)
1417 msymbol
= lookup_minimal_symbol (main_name (), NULL
, symfile_objfile
);
1418 if (msymbol
== NULL
)
1420 /* Make certain that the code, and not descriptor, address is
1422 maddr
= gdbarch_convert_from_func_ptr_addr (get_frame_arch (this_frame
),
1423 SYMBOL_VALUE_ADDRESS (msymbol
),
1425 return maddr
== get_frame_func (this_frame
);
1428 /* Test whether THIS_FRAME is inside the process entry point function. */
1431 inside_entry_func (struct frame_info
*this_frame
)
1433 return (get_frame_func (this_frame
) == entry_point_address ());
1436 /* Return a structure containing various interesting information about
1437 the frame that called THIS_FRAME. Returns NULL if there is entier
1438 no such frame or the frame fails any of a set of target-independent
1439 condition that should terminate the frame chain (e.g., as unwinding
1442 This function should not contain target-dependent tests, such as
1443 checking whether the program-counter is zero. */
1446 get_prev_frame (struct frame_info
*this_frame
)
1448 struct frame_info
*prev_frame
;
1450 /* Return the inner-most frame, when the caller passes in NULL. */
1451 /* NOTE: cagney/2002-11-09: Not sure how this would happen. The
1452 caller should have previously obtained a valid frame using
1453 get_selected_frame() and then called this code - only possibility
1454 I can think of is code behaving badly.
1456 NOTE: cagney/2003-01-10: Talk about code behaving badly. Check
1457 block_innermost_frame(). It does the sequence: frame = NULL;
1458 while (1) { frame = get_prev_frame (frame); .... }. Ulgh! Why
1459 it couldn't be written better, I don't know.
1461 NOTE: cagney/2003-01-11: I suspect what is happening in
1462 block_innermost_frame() is, when the target has no state
1463 (registers, memory, ...), it is still calling this function. The
1464 assumption being that this function will return NULL indicating
1465 that a frame isn't possible, rather than checking that the target
1466 has state and then calling get_current_frame() and
1467 get_prev_frame(). This is a guess mind. */
1468 if (this_frame
== NULL
)
1470 /* NOTE: cagney/2002-11-09: There was a code segment here that
1471 would error out when CURRENT_FRAME was NULL. The comment
1472 that went with it made the claim ...
1474 ``This screws value_of_variable, which just wants a nice
1475 clean NULL return from block_innermost_frame if there are no
1476 frames. I don't think I've ever seen this message happen
1477 otherwise. And returning NULL here is a perfectly legitimate
1480 Per the above, this code shouldn't even be called with a NULL
1482 frame_debug_got_null_frame (gdb_stdlog
, this_frame
, "this_frame NULL");
1483 return current_frame
;
1486 /* There is always a frame. If this assertion fails, suspect that
1487 something should be calling get_selected_frame() or
1488 get_current_frame(). */
1489 gdb_assert (this_frame
!= NULL
);
1491 /* tausq/2004-12-07: Dummy frames are skipped because it doesn't make much
1492 sense to stop unwinding at a dummy frame. One place where a dummy
1493 frame may have an address "inside_main_func" is on HPUX. On HPUX, the
1494 pcsqh register (space register for the instruction at the head of the
1495 instruction queue) cannot be written directly; the only way to set it
1496 is to branch to code that is in the target space. In order to implement
1497 frame dummies on HPUX, the called function is made to jump back to where
1498 the inferior was when the user function was called. If gdb was inside
1499 the main function when we created the dummy frame, the dummy frame will
1500 point inside the main function. */
1501 if (this_frame
->level
>= 0
1502 && get_frame_type (this_frame
) != DUMMY_FRAME
1503 && !backtrace_past_main
1504 && inside_main_func (this_frame
))
1505 /* Don't unwind past main(). Note, this is done _before_ the
1506 frame has been marked as previously unwound. That way if the
1507 user later decides to enable unwinds past main(), that will
1508 automatically happen. */
1510 frame_debug_got_null_frame (gdb_stdlog
, this_frame
, "inside main func");
1514 /* If the user's backtrace limit has been exceeded, stop. We must
1515 add two to the current level; one of those accounts for backtrace_limit
1516 being 1-based and the level being 0-based, and the other accounts for
1517 the level of the new frame instead of the level of the current
1519 if (this_frame
->level
+ 2 > backtrace_limit
)
1521 frame_debug_got_null_frame (gdb_stdlog
, this_frame
,
1522 "backtrace limit exceeded");
1526 /* If we're already inside the entry function for the main objfile,
1527 then it isn't valid. Don't apply this test to a dummy frame -
1528 dummy frame PCs typically land in the entry func. Don't apply
1529 this test to the sentinel frame. Sentinel frames should always
1530 be allowed to unwind. */
1531 /* NOTE: cagney/2003-07-07: Fixed a bug in inside_main_func() -
1532 wasn't checking for "main" in the minimal symbols. With that
1533 fixed asm-source tests now stop in "main" instead of halting the
1534 backtrace in weird and wonderful ways somewhere inside the entry
1535 file. Suspect that tests for inside the entry file/func were
1536 added to work around that (now fixed) case. */
1537 /* NOTE: cagney/2003-07-15: danielj (if I'm reading it right)
1538 suggested having the inside_entry_func test use the
1539 inside_main_func() msymbol trick (along with entry_point_address()
1540 I guess) to determine the address range of the start function.
1541 That should provide a far better stopper than the current
1543 /* NOTE: tausq/2004-10-09: this is needed if, for example, the compiler
1544 applied tail-call optimizations to main so that a function called
1545 from main returns directly to the caller of main. Since we don't
1546 stop at main, we should at least stop at the entry point of the
1548 if (!backtrace_past_entry
1549 && get_frame_type (this_frame
) != DUMMY_FRAME
&& this_frame
->level
>= 0
1550 && inside_entry_func (this_frame
))
1552 frame_debug_got_null_frame (gdb_stdlog
, this_frame
, "inside entry func");
1556 /* Assume that the only way to get a zero PC is through something
1557 like a SIGSEGV or a dummy frame, and hence that NORMAL frames
1558 will never unwind a zero PC. */
1559 if (this_frame
->level
> 0
1560 && get_frame_type (this_frame
) == NORMAL_FRAME
1561 && get_frame_type (get_next_frame (this_frame
)) == NORMAL_FRAME
1562 && get_frame_pc (this_frame
) == 0)
1564 frame_debug_got_null_frame (gdb_stdlog
, this_frame
, "zero PC");
1568 return get_prev_frame_1 (this_frame
);
1572 get_frame_pc (struct frame_info
*frame
)
1574 gdb_assert (frame
->next
!= NULL
);
1575 return frame_pc_unwind (frame
->next
);
1578 /* Return an address that falls within THIS_FRAME's code block. */
1581 get_frame_address_in_block (struct frame_info
*this_frame
)
1583 /* A draft address. */
1584 CORE_ADDR pc
= get_frame_pc (this_frame
);
1586 struct frame_info
*next_frame
= this_frame
->next
;
1588 /* Calling get_frame_pc returns the resume address for THIS_FRAME.
1589 Normally the resume address is inside the body of the function
1590 associated with THIS_FRAME, but there is a special case: when
1591 calling a function which the compiler knows will never return
1592 (for instance abort), the call may be the very last instruction
1593 in the calling function. The resume address will point after the
1594 call and may be at the beginning of a different function
1597 If THIS_FRAME is a signal frame or dummy frame, then we should
1598 not adjust the unwound PC. For a dummy frame, GDB pushed the
1599 resume address manually onto the stack. For a signal frame, the
1600 OS may have pushed the resume address manually and invoked the
1601 handler (e.g. GNU/Linux), or invoked the trampoline which called
1602 the signal handler - but in either case the signal handler is
1603 expected to return to the trampoline. So in both of these
1604 cases we know that the resume address is executable and
1605 related. So we only need to adjust the PC if THIS_FRAME
1606 is a normal function.
1608 If the program has been interrupted while THIS_FRAME is current,
1609 then clearly the resume address is inside the associated
1610 function. There are three kinds of interruption: debugger stop
1611 (next frame will be SENTINEL_FRAME), operating system
1612 signal or exception (next frame will be SIGTRAMP_FRAME),
1613 or debugger-induced function call (next frame will be
1614 DUMMY_FRAME). So we only need to adjust the PC if
1615 NEXT_FRAME is a normal function.
1617 We check the type of NEXT_FRAME first, since it is already
1618 known; frame type is determined by the unwinder, and since
1619 we have THIS_FRAME we've already selected an unwinder for
1621 if (get_frame_type (next_frame
) == NORMAL_FRAME
1622 && get_frame_type (this_frame
) == NORMAL_FRAME
)
1629 pc_notcurrent (struct frame_info
*frame
)
1631 /* If FRAME is not the innermost frame, that normally means that
1632 FRAME->pc points at the return instruction (which is *after* the
1633 call instruction), and we want to get the line containing the
1634 call (because the call is where the user thinks the program is).
1635 However, if the next frame is either a SIGTRAMP_FRAME or a
1636 DUMMY_FRAME, then the next frame will contain a saved interrupt
1637 PC and such a PC indicates the current (rather than next)
1638 instruction/line, consequently, for such cases, want to get the
1639 line containing fi->pc. */
1640 struct frame_info
*next
= get_next_frame (frame
);
1641 int notcurrent
= (next
!= NULL
&& get_frame_type (next
) == NORMAL_FRAME
);
1646 find_frame_sal (struct frame_info
*frame
, struct symtab_and_line
*sal
)
1648 (*sal
) = find_pc_line (get_frame_pc (frame
), pc_notcurrent (frame
));
1651 /* Per "frame.h", return the ``address'' of the frame. Code should
1652 really be using get_frame_id(). */
1654 get_frame_base (struct frame_info
*fi
)
1656 return get_frame_id (fi
).stack_addr
;
1659 /* High-level offsets into the frame. Used by the debug info. */
1662 get_frame_base_address (struct frame_info
*fi
)
1664 if (get_frame_type (fi
) != NORMAL_FRAME
)
1666 if (fi
->base
== NULL
)
1667 fi
->base
= frame_base_find_by_frame (fi
);
1668 /* Sneaky: If the low-level unwind and high-level base code share a
1669 common unwinder, let them share the prologue cache. */
1670 if (fi
->base
->unwind
== fi
->unwind
)
1671 return fi
->base
->this_base (fi
, &fi
->prologue_cache
);
1672 return fi
->base
->this_base (fi
, &fi
->base_cache
);
1676 get_frame_locals_address (struct frame_info
*fi
)
1679 if (get_frame_type (fi
) != NORMAL_FRAME
)
1681 /* If there isn't a frame address method, find it. */
1682 if (fi
->base
== NULL
)
1683 fi
->base
= frame_base_find_by_frame (fi
);
1684 /* Sneaky: If the low-level unwind and high-level base code share a
1685 common unwinder, let them share the prologue cache. */
1686 if (fi
->base
->unwind
== fi
->unwind
)
1687 return fi
->base
->this_locals (fi
, &fi
->prologue_cache
);
1688 return fi
->base
->this_locals (fi
, &fi
->base_cache
);
1692 get_frame_args_address (struct frame_info
*fi
)
1695 if (get_frame_type (fi
) != NORMAL_FRAME
)
1697 /* If there isn't a frame address method, find it. */
1698 if (fi
->base
== NULL
)
1699 fi
->base
= frame_base_find_by_frame (fi
);
1700 /* Sneaky: If the low-level unwind and high-level base code share a
1701 common unwinder, let them share the prologue cache. */
1702 if (fi
->base
->unwind
== fi
->unwind
)
1703 return fi
->base
->this_args (fi
, &fi
->prologue_cache
);
1704 return fi
->base
->this_args (fi
, &fi
->base_cache
);
1707 /* Level of the selected frame: 0 for innermost, 1 for its caller, ...
1708 or -1 for a NULL frame. */
1711 frame_relative_level (struct frame_info
*fi
)
1720 get_frame_type (struct frame_info
*frame
)
1722 if (frame
->unwind
== NULL
)
1723 /* Initialize the frame's unwinder because that's what
1724 provides the frame's type. */
1725 frame
->unwind
= frame_unwind_find_by_frame (frame
, &frame
->prologue_cache
);
1726 return frame
->unwind
->type
;
1730 deprecated_update_frame_pc_hack (struct frame_info
*frame
, CORE_ADDR pc
)
1733 fprintf_unfiltered (gdb_stdlog
,
1734 "{ deprecated_update_frame_pc_hack (frame=%d,pc=0x%s) }\n",
1735 frame
->level
, paddr_nz (pc
));
1736 /* NOTE: cagney/2003-03-11: Some architectures (e.g., Arm) are
1737 maintaining a locally allocated frame object. Since such frames
1738 are not in the frame chain, it isn't possible to assume that the
1739 frame has a next. Sigh. */
1740 if (frame
->next
!= NULL
)
1742 /* While we're at it, update this frame's cached PC value, found
1743 in the next frame. Oh for the day when "struct frame_info"
1744 is opaque and this hack on hack can just go away. */
1745 frame
->next
->prev_pc
.value
= pc
;
1746 frame
->next
->prev_pc
.p
= 1;
1751 deprecated_update_frame_base_hack (struct frame_info
*frame
, CORE_ADDR base
)
1754 fprintf_unfiltered (gdb_stdlog
,
1755 "{ deprecated_update_frame_base_hack (frame=%d,base=0x%s) }\n",
1756 frame
->level
, paddr_nz (base
));
1757 /* See comment in "frame.h". */
1758 frame
->this_id
.value
.stack_addr
= base
;
1761 /* Memory access methods. */
1764 get_frame_memory (struct frame_info
*this_frame
, CORE_ADDR addr
,
1765 gdb_byte
*buf
, int len
)
1767 read_memory (addr
, buf
, len
);
1771 get_frame_memory_signed (struct frame_info
*this_frame
, CORE_ADDR addr
,
1774 return read_memory_integer (addr
, len
);
1778 get_frame_memory_unsigned (struct frame_info
*this_frame
, CORE_ADDR addr
,
1781 return read_memory_unsigned_integer (addr
, len
);
1785 safe_frame_unwind_memory (struct frame_info
*this_frame
,
1786 CORE_ADDR addr
, gdb_byte
*buf
, int len
)
1788 /* NOTE: target_read_memory returns zero on success! */
1789 return !target_read_memory (addr
, buf
, len
);
1792 /* Architecture method. */
1795 get_frame_arch (struct frame_info
*this_frame
)
1797 return current_gdbarch
;
1800 /* Stack pointer methods. */
1803 get_frame_sp (struct frame_info
*this_frame
)
1805 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
1806 /* Normality - an architecture that provides a way of obtaining any
1807 frame inner-most address. */
1808 if (gdbarch_unwind_sp_p (gdbarch
))
1809 /* NOTE drow/2008-06-28: gdbarch_unwind_sp could be converted to
1810 operate on THIS_FRAME now. */
1811 return gdbarch_unwind_sp (gdbarch
, this_frame
->next
);
1812 /* Now things are really are grim. Hope that the value returned by
1813 the gdbarch_sp_regnum register is meaningful. */
1814 if (gdbarch_sp_regnum (gdbarch
) >= 0)
1815 return get_frame_register_unsigned (this_frame
,
1816 gdbarch_sp_regnum (gdbarch
));
1817 internal_error (__FILE__
, __LINE__
, _("Missing unwind SP method"));
1820 /* Return the reason why we can't unwind past FRAME. */
1822 enum unwind_stop_reason
1823 get_frame_unwind_stop_reason (struct frame_info
*frame
)
1825 /* If we haven't tried to unwind past this point yet, then assume
1826 that unwinding would succeed. */
1827 if (frame
->prev_p
== 0)
1828 return UNWIND_NO_REASON
;
1830 /* Otherwise, we set a reason when we succeeded (or failed) to
1832 return frame
->stop_reason
;
1835 /* Return a string explaining REASON. */
1838 frame_stop_reason_string (enum unwind_stop_reason reason
)
1842 case UNWIND_NULL_ID
:
1843 return _("unwinder did not report frame ID");
1845 case UNWIND_INNER_ID
:
1846 return _("previous frame inner to this frame (corrupt stack?)");
1848 case UNWIND_SAME_ID
:
1849 return _("previous frame identical to this frame (corrupt stack?)");
1851 case UNWIND_NO_SAVED_PC
:
1852 return _("frame did not save the PC");
1854 case UNWIND_NO_REASON
:
1855 case UNWIND_FIRST_ERROR
:
1857 internal_error (__FILE__
, __LINE__
,
1858 "Invalid frame stop reason");
1862 /* Clean up after a failed (wrong unwinder) attempt to unwind past
1866 frame_cleanup_after_sniffer (void *arg
)
1868 struct frame_info
*frame
= arg
;
1870 /* The sniffer should not allocate a prologue cache if it did not
1871 match this frame. */
1872 gdb_assert (frame
->prologue_cache
== NULL
);
1874 /* No sniffer should extend the frame chain; sniff based on what is
1876 gdb_assert (!frame
->prev_p
);
1878 /* The sniffer should not check the frame's ID; that's circular. */
1879 gdb_assert (!frame
->this_id
.p
);
1881 /* Clear cached fields dependent on the unwinder.
1883 The previous PC is independent of the unwinder, but the previous
1884 function is not (see get_frame_address_in_block). */
1885 frame
->prev_func
.p
= 0;
1886 frame
->prev_func
.addr
= 0;
1888 /* Discard the unwinder last, so that we can easily find it if an assertion
1889 in this function triggers. */
1890 frame
->unwind
= NULL
;
1893 /* Set FRAME's unwinder temporarily, so that we can call a sniffer.
1894 Return a cleanup which should be called if unwinding fails, and
1895 discarded if it succeeds. */
1898 frame_prepare_for_sniffer (struct frame_info
*frame
,
1899 const struct frame_unwind
*unwind
)
1901 gdb_assert (frame
->unwind
== NULL
);
1902 frame
->unwind
= unwind
;
1903 return make_cleanup (frame_cleanup_after_sniffer
, frame
);
1906 extern initialize_file_ftype _initialize_frame
; /* -Wmissing-prototypes */
1908 static struct cmd_list_element
*set_backtrace_cmdlist
;
1909 static struct cmd_list_element
*show_backtrace_cmdlist
;
1912 set_backtrace_cmd (char *args
, int from_tty
)
1914 help_list (set_backtrace_cmdlist
, "set backtrace ", -1, gdb_stdout
);
1918 show_backtrace_cmd (char *args
, int from_tty
)
1920 cmd_show_list (show_backtrace_cmdlist
, from_tty
, "");
1924 _initialize_frame (void)
1926 obstack_init (&frame_cache_obstack
);
1928 observer_attach_target_changed (frame_observer_target_changed
);
1930 add_prefix_cmd ("backtrace", class_maintenance
, set_backtrace_cmd
, _("\
1931 Set backtrace specific variables.\n\
1932 Configure backtrace variables such as the backtrace limit"),
1933 &set_backtrace_cmdlist
, "set backtrace ",
1934 0/*allow-unknown*/, &setlist
);
1935 add_prefix_cmd ("backtrace", class_maintenance
, show_backtrace_cmd
, _("\
1936 Show backtrace specific variables\n\
1937 Show backtrace variables such as the backtrace limit"),
1938 &show_backtrace_cmdlist
, "show backtrace ",
1939 0/*allow-unknown*/, &showlist
);
1941 add_setshow_boolean_cmd ("past-main", class_obscure
,
1942 &backtrace_past_main
, _("\
1943 Set whether backtraces should continue past \"main\"."), _("\
1944 Show whether backtraces should continue past \"main\"."), _("\
1945 Normally the caller of \"main\" is not of interest, so GDB will terminate\n\
1946 the backtrace at \"main\". Set this variable if you need to see the rest\n\
1947 of the stack trace."),
1949 show_backtrace_past_main
,
1950 &set_backtrace_cmdlist
,
1951 &show_backtrace_cmdlist
);
1953 add_setshow_boolean_cmd ("past-entry", class_obscure
,
1954 &backtrace_past_entry
, _("\
1955 Set whether backtraces should continue past the entry point of a program."),
1957 Show whether backtraces should continue past the entry point of a program."),
1959 Normally there are no callers beyond the entry point of a program, so GDB\n\
1960 will terminate the backtrace there. Set this variable if you need to see \n\
1961 the rest of the stack trace."),
1963 show_backtrace_past_entry
,
1964 &set_backtrace_cmdlist
,
1965 &show_backtrace_cmdlist
);
1967 add_setshow_integer_cmd ("limit", class_obscure
,
1968 &backtrace_limit
, _("\
1969 Set an upper bound on the number of backtrace levels."), _("\
1970 Show the upper bound on the number of backtrace levels."), _("\
1971 No more than the specified number of frames can be displayed or examined.\n\
1972 Zero is unlimited."),
1974 show_backtrace_limit
,
1975 &set_backtrace_cmdlist
,
1976 &show_backtrace_cmdlist
);
1978 /* Debug this files internals. */
1979 add_setshow_zinteger_cmd ("frame", class_maintenance
, &frame_debug
, _("\
1980 Set frame debugging."), _("\
1981 Show frame debugging."), _("\
1982 When non-zero, frame specific internal debugging is enabled."),
1985 &setdebuglist
, &showdebuglist
);