1 /* Code dealing with dummy stack frames, for GDB, the GNU debugger.
3 Copyright (C) 1986-2015 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"
30 #include "gdbthread.h"
35 /* This frame's ID. Must match the value returned by
39 /* The thread this dummy_frame relates to. */
43 /* Return whether dummy_frame_id *ID1 and *ID2 are equal. */
46 dummy_frame_id_eq (struct dummy_frame_id *id1,
47 struct dummy_frame_id *id2)
49 return frame_id_eq (id1->id, id2->id) && ptid_equal (id1->ptid, id2->ptid);
52 /* Dummy frame. This saves the processor state just prior to setting
53 up the inferior function call. Older targets save the registers
54 on the target stack (but that really slows down function calls). */
58 struct dummy_frame *next;
60 /* An id represents a dummy frame. */
61 struct dummy_frame_id id;
63 /* The caller's state prior to the call. */
64 struct infcall_suspend_state *caller_state;
66 /* If non-NULL, a destructor that is run when this dummy frame is freed. */
67 dummy_frame_dtor_ftype *dtor;
69 /* Arbitrary data that is passed to DTOR. */
73 static struct dummy_frame *dummy_frame_stack = NULL;
75 /* Push the caller's state, along with the dummy frame info, onto the
79 dummy_frame_push (struct infcall_suspend_state *caller_state,
80 const struct frame_id *dummy_id, ptid_t ptid)
82 struct dummy_frame *dummy_frame;
84 dummy_frame = XCNEW (struct dummy_frame);
85 dummy_frame->caller_state = caller_state;
86 dummy_frame->id.id = (*dummy_id);
87 dummy_frame->id.ptid = ptid;
88 dummy_frame->next = dummy_frame_stack;
89 dummy_frame_stack = dummy_frame;
92 /* Remove *DUMMY_PTR from the dummy frame stack. */
95 remove_dummy_frame (struct dummy_frame **dummy_ptr)
97 struct dummy_frame *dummy = *dummy_ptr;
99 if (dummy->dtor != NULL)
100 dummy->dtor (dummy->dtor_data, 0);
102 *dummy_ptr = dummy->next;
103 discard_infcall_suspend_state (dummy->caller_state);
107 /* Delete any breakpoint B which is a momentary breakpoint for return from
108 inferior call matching DUMMY_VOIDP. */
111 pop_dummy_frame_bpt (struct breakpoint *b, void *dummy_voidp)
113 struct dummy_frame *dummy = dummy_voidp;
115 if (b->thread == pid_to_thread_id (dummy->id.ptid)
116 && b->disposition == disp_del && frame_id_eq (b->frame_id, dummy->id.id))
118 while (b->related_breakpoint != b)
119 delete_breakpoint (b->related_breakpoint);
121 delete_breakpoint (b);
123 /* Stop the traversal. */
127 /* Continue the traversal. */
131 /* Pop *DUMMY_PTR, restoring program state to that before the
132 frame was created. */
135 pop_dummy_frame (struct dummy_frame **dummy_ptr)
137 struct dummy_frame *dummy = *dummy_ptr;
139 gdb_assert (ptid_equal (dummy->id.ptid, inferior_ptid));
141 if (dummy->dtor != NULL)
142 dummy->dtor (dummy->dtor_data, 1);
144 restore_infcall_suspend_state (dummy->caller_state);
146 iterate_over_breakpoints (pop_dummy_frame_bpt, dummy);
148 /* restore_infcall_control_state frees inf_state,
149 all that remains is to pop *dummy_ptr. */
150 *dummy_ptr = dummy->next;
153 /* We've made right mess of GDB's local state, just discard
155 reinit_frame_cache ();
159 Return NULL if not found. */
161 static struct dummy_frame **
162 lookup_dummy_frame (struct dummy_frame_id *dummy_id)
164 struct dummy_frame **dp;
166 for (dp = &dummy_frame_stack; *dp != NULL; dp = &(*dp)->next)
168 if (dummy_frame_id_eq (&(*dp)->id, dummy_id))
175 /* Find the dummy frame by DUMMY_ID and PTID, and pop it, restoring
176 program state to that before the frame was created.
177 On return reinit_frame_cache has been called.
178 If the frame isn't found, flag an internal error. */
181 dummy_frame_pop (struct frame_id dummy_id, ptid_t ptid)
183 struct dummy_frame **dp;
184 struct dummy_frame_id id = { dummy_id, ptid };
186 dp = lookup_dummy_frame (&id);
187 gdb_assert (dp != NULL);
189 pop_dummy_frame (dp);
192 /* Find the dummy frame by DUMMY_ID and PTID and drop it. Do nothing
193 if it is not found. Do not restore its state into inferior, just
197 dummy_frame_discard (struct frame_id dummy_id, ptid_t ptid)
199 struct dummy_frame **dp;
200 struct dummy_frame_id id = { dummy_id, ptid };
202 dp = lookup_dummy_frame (&id);
204 remove_dummy_frame (dp);
207 /* See dummy-frame.h. */
210 register_dummy_frame_dtor (struct frame_id dummy_id, ptid_t ptid,
211 dummy_frame_dtor_ftype *dtor, void *dtor_data)
213 struct dummy_frame_id id = { dummy_id, ptid };
214 struct dummy_frame **dp, *d;
216 dp = lookup_dummy_frame (&id);
217 gdb_assert (dp != NULL);
219 gdb_assert (d->dtor == NULL);
221 d->dtor_data = dtor_data;
224 /* See dummy-frame.h. */
227 find_dummy_frame_dtor (dummy_frame_dtor_ftype *dtor, void *dtor_data)
229 struct dummy_frame *d;
231 for (d = dummy_frame_stack; d != NULL; d = d->next)
232 if (d->dtor == dtor && d->dtor_data == dtor_data)
237 /* There may be stale dummy frames, perhaps left over from when an uncaught
238 longjmp took us out of a function that was called by the debugger. Clean
239 them up at least once whenever we start a new inferior. */
242 cleanup_dummy_frames (struct target_ops *target, int from_tty)
244 while (dummy_frame_stack != NULL)
245 remove_dummy_frame (&dummy_frame_stack);
248 /* Return the dummy frame cache, it contains both the ID, and a
249 pointer to the regcache. */
250 struct dummy_frame_cache
252 struct frame_id this_id;
253 struct regcache *prev_regcache;
257 dummy_frame_sniffer (const struct frame_unwind *self,
258 struct frame_info *this_frame,
259 void **this_prologue_cache)
261 /* When unwinding a normal frame, the stack structure is determined
262 by analyzing the frame's function's code (be it using brute force
263 prologue analysis, or the dwarf2 CFI). In the case of a dummy
264 frame, that simply isn't possible. The PC is either the program
265 entry point, or some random address on the stack. Trying to use
266 that PC to apply standard frame ID unwind techniques is just
267 asking for trouble. */
269 /* Don't bother unless there is at least one dummy frame. */
270 if (dummy_frame_stack != NULL)
272 struct dummy_frame *dummyframe;
273 /* Use an architecture specific method to extract this frame's
274 dummy ID, assuming it is a dummy frame. */
275 struct frame_id this_id
276 = gdbarch_dummy_id (get_frame_arch (this_frame), this_frame);
277 struct dummy_frame_id dummy_id = { this_id, inferior_ptid };
279 /* Use that ID to find the corresponding cache entry. */
280 for (dummyframe = dummy_frame_stack;
282 dummyframe = dummyframe->next)
284 if (dummy_frame_id_eq (&dummyframe->id, &dummy_id))
286 struct dummy_frame_cache *cache;
288 cache = FRAME_OBSTACK_ZALLOC (struct dummy_frame_cache);
289 cache->prev_regcache = get_infcall_suspend_state_regcache
290 (dummyframe->caller_state);
291 cache->this_id = this_id;
292 (*this_prologue_cache) = cache;
300 /* Given a call-dummy dummy-frame, return the registers. Here the
301 register value is taken from the local copy of the register buffer. */
303 static struct value *
304 dummy_frame_prev_register (struct frame_info *this_frame,
305 void **this_prologue_cache,
308 struct dummy_frame_cache *cache = (*this_prologue_cache);
309 struct gdbarch *gdbarch = get_frame_arch (this_frame);
310 struct value *reg_val;
312 /* The dummy-frame sniffer always fills in the cache. */
313 gdb_assert (cache != NULL);
315 /* Describe the register's location. Generic dummy frames always
316 have the register value in an ``expression''. */
317 reg_val = value_zero (register_type (gdbarch, regnum), not_lval);
319 /* Use the regcache_cooked_read() method so that it, on the fly,
320 constructs either a raw or pseudo register from the raw
322 regcache_cooked_read (cache->prev_regcache, regnum,
323 value_contents_writeable (reg_val));
327 /* Assuming that THIS_FRAME is a dummy, return its ID. That ID is
328 determined by examining the NEXT frame's unwound registers using
329 the method dummy_id(). As a side effect, THIS dummy frame's
330 dummy cache is located and saved in THIS_PROLOGUE_CACHE. */
333 dummy_frame_this_id (struct frame_info *this_frame,
334 void **this_prologue_cache,
335 struct frame_id *this_id)
337 /* The dummy-frame sniffer always fills in the cache. */
338 struct dummy_frame_cache *cache = (*this_prologue_cache);
340 gdb_assert (cache != NULL);
341 (*this_id) = cache->this_id;
344 const struct frame_unwind dummy_frame_unwind =
347 default_frame_unwind_stop_reason,
349 dummy_frame_prev_register,
355 fprint_dummy_frames (struct ui_file *file)
357 struct dummy_frame *s;
359 for (s = dummy_frame_stack; s != NULL; s = s->next)
361 gdb_print_host_address (s, file);
362 fprintf_unfiltered (file, ":");
363 fprintf_unfiltered (file, " id=");
364 fprint_frame_id (file, s->id.id);
365 fprintf_unfiltered (file, ", ptid=%s",
366 target_pid_to_str (s->id.ptid));
367 fprintf_unfiltered (file, "\n");
372 maintenance_print_dummy_frames (char *args, int from_tty)
375 fprint_dummy_frames (gdb_stdout);
378 struct cleanup *cleanups;
379 struct ui_file *file = gdb_fopen (args, "w");
382 perror_with_name (_("maintenance print dummy-frames"));
383 cleanups = make_cleanup_ui_file_delete (file);
384 fprint_dummy_frames (file);
385 do_cleanups (cleanups);
389 extern void _initialize_dummy_frame (void);
392 _initialize_dummy_frame (void)
394 add_cmd ("dummy-frames", class_maintenance, maintenance_print_dummy_frames,
395 _("Print the contents of the internal dummy-frame stack."),
396 &maintenanceprintlist);
398 observer_attach_inferior_created (cleanup_dummy_frames);