1 /* Code dealing with dummy stack frames, for GDB, the GNU debugger.
3 Copyright (C) 1986-2024 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
22 #include "dummy-frame.h"
26 #include "frame-unwind.h"
29 #include "observable.h"
30 #include "gdbthread.h"
36 /* This frame's ID. Must match the value returned by
40 /* The thread this dummy_frame relates to. */
44 /* Return whether dummy_frame_id *ID1 and *ID2 are equal. */
47 dummy_frame_id_eq (struct dummy_frame_id
*id1
,
48 struct dummy_frame_id
*id2
)
50 return id1
->id
== id2
->id
&& id1
->thread
== id2
->thread
;
53 /* List of dummy_frame destructors. */
55 struct dummy_frame_dtor_list
57 /* Next element in the list or NULL if this is the last element. */
58 struct dummy_frame_dtor_list
*next
;
60 /* If non-NULL, a destructor that is run when this dummy frame is freed. */
61 dummy_frame_dtor_ftype
*dtor
;
63 /* Arbitrary data that is passed to DTOR. */
67 /* Dummy frame. This saves the processor state just prior to setting
68 up the inferior function call. Older targets save the registers
69 on the target stack (but that really slows down function calls). */
73 struct dummy_frame
*next
;
75 /* An id represents a dummy frame. */
76 struct dummy_frame_id id
;
78 /* The caller's state prior to the call. */
79 struct infcall_suspend_state
*caller_state
;
81 /* First element of destructors list or NULL if there are no
82 destructors registered for this dummy_frame. */
83 struct dummy_frame_dtor_list
*dtor_list
;
86 static struct dummy_frame
*dummy_frame_stack
= NULL
;
88 /* Push the caller's state, along with the dummy frame info, onto the
92 dummy_frame_push (struct infcall_suspend_state
*caller_state
,
93 const frame_id
*dummy_id
, thread_info
*thread
)
95 struct dummy_frame
*dummy_frame
;
97 dummy_frame
= XCNEW (struct dummy_frame
);
98 dummy_frame
->caller_state
= caller_state
;
99 dummy_frame
->id
.id
= (*dummy_id
);
100 dummy_frame
->id
.thread
= thread
;
101 dummy_frame
->next
= dummy_frame_stack
;
102 dummy_frame_stack
= dummy_frame
;
105 /* Remove *DUMMY_PTR from the dummy frame stack. */
108 remove_dummy_frame (struct dummy_frame
**dummy_ptr
)
110 struct dummy_frame
*dummy
= *dummy_ptr
;
112 while (dummy
->dtor_list
!= NULL
)
114 struct dummy_frame_dtor_list
*list
= dummy
->dtor_list
;
116 dummy
->dtor_list
= list
->next
;
117 list
->dtor (list
->dtor_data
, 0);
121 *dummy_ptr
= dummy
->next
;
122 discard_infcall_suspend_state (dummy
->caller_state
);
126 /* Delete any breakpoint B which is a momentary breakpoint for return from
127 inferior call matching DUMMY_VOIDP. */
130 pop_dummy_frame_bpt (struct breakpoint
*b
, struct dummy_frame
*dummy
)
132 if (b
->thread
== dummy
->id
.thread
->global_num
133 && b
->disposition
== disp_del
&& b
->frame_id
== dummy
->id
.id
)
135 while (b
->related_breakpoint
!= b
)
136 delete_breakpoint (b
->related_breakpoint
);
138 delete_breakpoint (b
);
140 /* Stop the traversal. */
144 /* Continue the traversal. */
148 /* Pop *DUMMY_PTR, restoring program state to that before the
149 frame was created. */
152 pop_dummy_frame (struct dummy_frame
**dummy_ptr
)
154 struct dummy_frame
*dummy
= *dummy_ptr
;
156 gdb_assert (dummy
->id
.thread
== inferior_thread ());
158 while (dummy
->dtor_list
!= NULL
)
160 struct dummy_frame_dtor_list
*list
= dummy
->dtor_list
;
162 dummy
->dtor_list
= list
->next
;
163 list
->dtor (list
->dtor_data
, 1);
167 restore_infcall_suspend_state (dummy
->caller_state
);
169 for (breakpoint
&bp
: all_breakpoints_safe ())
170 if (pop_dummy_frame_bpt (&bp
, dummy
))
173 /* restore_infcall_control_state frees inf_state,
174 all that remains is to pop *dummy_ptr. */
175 *dummy_ptr
= dummy
->next
;
178 /* We've made right mess of GDB's local state, just discard
180 reinit_frame_cache ();
184 Return NULL if not found. */
186 static struct dummy_frame
**
187 lookup_dummy_frame (struct dummy_frame_id
*dummy_id
)
189 struct dummy_frame
**dp
;
191 for (dp
= &dummy_frame_stack
; *dp
!= NULL
; dp
= &(*dp
)->next
)
193 if (dummy_frame_id_eq (&(*dp
)->id
, dummy_id
))
200 /* Find the dummy frame by DUMMY_ID and THREAD, and pop it, restoring
201 program state to that before the frame was created.
202 On return reinit_frame_cache has been called.
203 If the frame isn't found, flag an internal error. */
206 dummy_frame_pop (frame_id dummy_id
, thread_info
*thread
)
208 struct dummy_frame
**dp
;
209 struct dummy_frame_id id
= { dummy_id
, thread
};
211 dp
= lookup_dummy_frame (&id
);
212 gdb_assert (dp
!= NULL
);
214 pop_dummy_frame (dp
);
217 /* Find the dummy frame by DUMMY_ID and PTID and drop it. Do nothing
218 if it is not found. Do not restore its state into inferior, just
222 dummy_frame_discard (struct frame_id dummy_id
, thread_info
*thread
)
224 struct dummy_frame
**dp
;
225 struct dummy_frame_id id
= { dummy_id
, thread
};
227 dp
= lookup_dummy_frame (&id
);
229 remove_dummy_frame (dp
);
232 /* See dummy-frame.h. */
235 register_dummy_frame_dtor (frame_id dummy_id
, thread_info
*thread
,
236 dummy_frame_dtor_ftype
*dtor
, void *dtor_data
)
238 struct dummy_frame_id id
= { dummy_id
, thread
};
239 struct dummy_frame
**dp
, *d
;
240 struct dummy_frame_dtor_list
*list
;
242 dp
= lookup_dummy_frame (&id
);
243 gdb_assert (dp
!= NULL
);
245 list
= XNEW (struct dummy_frame_dtor_list
);
246 list
->next
= d
->dtor_list
;
249 list
->dtor_data
= dtor_data
;
252 /* See dummy-frame.h. */
255 find_dummy_frame_dtor (dummy_frame_dtor_ftype
*dtor
, void *dtor_data
)
257 struct dummy_frame
*d
;
259 for (d
= dummy_frame_stack
; d
!= NULL
; d
= d
->next
)
261 struct dummy_frame_dtor_list
*list
;
263 for (list
= d
->dtor_list
; list
!= NULL
; list
= list
->next
)
264 if (list
->dtor
== dtor
&& list
->dtor_data
== dtor_data
)
270 /* There may be stale dummy frames, perhaps left over from when an uncaught
271 longjmp took us out of a function that was called by the debugger. Clean
272 them up at least once whenever we start a new inferior. */
275 cleanup_dummy_frames (inferior
*inf
)
277 while (dummy_frame_stack
!= NULL
)
278 remove_dummy_frame (&dummy_frame_stack
);
281 /* Return the dummy frame cache, it contains both the ID, and a
282 pointer to the regcache. */
283 struct dummy_frame_cache
285 struct frame_id this_id
;
286 readonly_detached_regcache
*prev_regcache
;
290 dummy_frame_sniffer (const struct frame_unwind
*self
,
291 const frame_info_ptr
&this_frame
,
292 void **this_prologue_cache
)
294 /* When unwinding a normal frame, the stack structure is determined
295 by analyzing the frame's function's code (be it using brute force
296 prologue analysis, or the dwarf2 CFI). In the case of a dummy
297 frame, that simply isn't possible. The PC is either the program
298 entry point, or some random address on the stack. Trying to use
299 that PC to apply standard frame ID unwind techniques is just
300 asking for trouble. */
302 /* Don't bother unless there is at least one dummy frame. */
303 if (dummy_frame_stack
!= NULL
)
305 struct dummy_frame
*dummyframe
;
306 /* Use an architecture specific method to extract this frame's
307 dummy ID, assuming it is a dummy frame. */
308 struct frame_id this_id
309 = gdbarch_dummy_id (get_frame_arch (this_frame
), this_frame
);
310 struct dummy_frame_id dummy_id
= { this_id
, inferior_thread () };
312 /* Use that ID to find the corresponding cache entry. */
313 for (dummyframe
= dummy_frame_stack
;
315 dummyframe
= dummyframe
->next
)
317 if (dummy_frame_id_eq (&dummyframe
->id
, &dummy_id
))
319 struct dummy_frame_cache
*cache
;
321 cache
= FRAME_OBSTACK_ZALLOC (struct dummy_frame_cache
);
322 cache
->prev_regcache
= get_infcall_suspend_state_regcache
323 (dummyframe
->caller_state
);
324 cache
->this_id
= this_id
;
325 (*this_prologue_cache
) = cache
;
333 /* Given a call-dummy dummy-frame, return the registers. Here the
334 register value is taken from the local copy of the register buffer. */
336 static struct value
*
337 dummy_frame_prev_register (const frame_info_ptr
&this_frame
,
338 void **this_prologue_cache
,
341 struct dummy_frame_cache
*cache
342 = (struct dummy_frame_cache
*) *this_prologue_cache
;
343 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
344 struct value
*reg_val
;
346 /* The dummy-frame sniffer always fills in the cache. */
347 gdb_assert (cache
!= NULL
);
349 /* Describe the register's location. Generic dummy frames always
350 have the register value in an ``expression''. */
351 reg_val
= value::zero (register_type (gdbarch
, regnum
), not_lval
);
353 /* Use the regcache_cooked_read() method so that it, on the fly,
354 constructs either a raw or pseudo register from the raw
356 cache
->prev_regcache
->cooked_read
357 (regnum
, reg_val
->contents_writeable ().data ());
361 /* Assuming that THIS_FRAME is a dummy, return its ID. That ID is
362 determined by examining the NEXT frame's unwound registers using
363 the method dummy_id(). As a side effect, THIS dummy frame's
364 dummy cache is located and saved in THIS_PROLOGUE_CACHE. */
367 dummy_frame_this_id (const frame_info_ptr
&this_frame
,
368 void **this_prologue_cache
,
369 struct frame_id
*this_id
)
371 /* The dummy-frame sniffer always fills in the cache. */
372 struct dummy_frame_cache
*cache
373 = (struct dummy_frame_cache
*) *this_prologue_cache
;
375 gdb_assert (cache
!= NULL
);
376 (*this_id
) = cache
->this_id
;
379 const struct frame_unwind dummy_frame_unwind
=
383 default_frame_unwind_stop_reason
,
385 dummy_frame_prev_register
,
390 /* See dummy-frame.h. */
393 default_dummy_id (struct gdbarch
*gdbarch
, const frame_info_ptr
&this_frame
)
397 sp
= get_frame_sp (this_frame
);
398 pc
= get_frame_pc (this_frame
);
399 return frame_id_build (sp
, pc
);
403 fprint_dummy_frames (struct ui_file
*file
)
405 struct dummy_frame
*s
;
407 for (s
= dummy_frame_stack
; s
!= NULL
; s
= s
->next
)
408 gdb_printf (file
, "%s: id=%s, ptid=%s\n",
409 host_address_to_string (s
),
410 s
->id
.id
.to_string ().c_str (),
411 s
->id
.thread
->ptid
.to_string ().c_str ());
415 maintenance_print_dummy_frames (const char *args
, int from_tty
)
418 fprint_dummy_frames (gdb_stdout
);
423 if (!file
.open (args
, "w"))
424 perror_with_name (_("maintenance print dummy-frames"));
425 fprint_dummy_frames (&file
);
429 void _initialize_dummy_frame ();
431 _initialize_dummy_frame ()
433 add_cmd ("dummy-frames", class_maintenance
, maintenance_print_dummy_frames
,
434 _("Print the contents of the internal dummy-frame stack."),
435 &maintenanceprintlist
);
437 gdb::observers::inferior_created
.attach (cleanup_dummy_frames
, "dummy-frame");