]>
Commit | Line | Data |
---|---|---|
1 | /* Code dealing with dummy stack frames, for GDB, the GNU debugger. | |
2 | ||
3 | Copyright (C) 1986-2019 Free Software Foundation, Inc. | |
4 | ||
5 | This file is part of GDB. | |
6 | ||
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. | |
11 | ||
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. | |
16 | ||
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/>. */ | |
19 | ||
20 | ||
21 | #include "defs.h" | |
22 | #include "dummy-frame.h" | |
23 | #include "regcache.h" | |
24 | #include "frame.h" | |
25 | #include "inferior.h" | |
26 | #include "frame-unwind.h" | |
27 | #include "command.h" | |
28 | #include "gdbcmd.h" | |
29 | #include "observable.h" | |
30 | #include "gdbthread.h" | |
31 | #include "infcall.h" | |
32 | ||
33 | struct dummy_frame_id | |
34 | { | |
35 | /* This frame's ID. Must match the value returned by | |
36 | gdbarch_dummy_id. */ | |
37 | struct frame_id id; | |
38 | ||
39 | /* The thread this dummy_frame relates to. */ | |
40 | thread_info *thread; | |
41 | }; | |
42 | ||
43 | /* Return whether dummy_frame_id *ID1 and *ID2 are equal. */ | |
44 | ||
45 | static int | |
46 | dummy_frame_id_eq (struct dummy_frame_id *id1, | |
47 | struct dummy_frame_id *id2) | |
48 | { | |
49 | return frame_id_eq (id1->id, id2->id) && id1->thread == id2->thread; | |
50 | } | |
51 | ||
52 | /* List of dummy_frame destructors. */ | |
53 | ||
54 | struct dummy_frame_dtor_list | |
55 | { | |
56 | /* Next element in the list or NULL if this is the last element. */ | |
57 | struct dummy_frame_dtor_list *next; | |
58 | ||
59 | /* If non-NULL, a destructor that is run when this dummy frame is freed. */ | |
60 | dummy_frame_dtor_ftype *dtor; | |
61 | ||
62 | /* Arbitrary data that is passed to DTOR. */ | |
63 | void *dtor_data; | |
64 | }; | |
65 | ||
66 | /* Dummy frame. This saves the processor state just prior to setting | |
67 | up the inferior function call. Older targets save the registers | |
68 | on the target stack (but that really slows down function calls). */ | |
69 | ||
70 | struct dummy_frame | |
71 | { | |
72 | struct dummy_frame *next; | |
73 | ||
74 | /* An id represents a dummy frame. */ | |
75 | struct dummy_frame_id id; | |
76 | ||
77 | /* The caller's state prior to the call. */ | |
78 | struct infcall_suspend_state *caller_state; | |
79 | ||
80 | /* First element of destructors list or NULL if there are no | |
81 | destructors registered for this dummy_frame. */ | |
82 | struct dummy_frame_dtor_list *dtor_list; | |
83 | }; | |
84 | ||
85 | static struct dummy_frame *dummy_frame_stack = NULL; | |
86 | ||
87 | /* Push the caller's state, along with the dummy frame info, onto the | |
88 | dummy-frame stack. */ | |
89 | ||
90 | void | |
91 | dummy_frame_push (struct infcall_suspend_state *caller_state, | |
92 | const frame_id *dummy_id, thread_info *thread) | |
93 | { | |
94 | struct dummy_frame *dummy_frame; | |
95 | ||
96 | dummy_frame = XCNEW (struct dummy_frame); | |
97 | dummy_frame->caller_state = caller_state; | |
98 | dummy_frame->id.id = (*dummy_id); | |
99 | dummy_frame->id.thread = thread; | |
100 | dummy_frame->next = dummy_frame_stack; | |
101 | dummy_frame_stack = dummy_frame; | |
102 | } | |
103 | ||
104 | /* Remove *DUMMY_PTR from the dummy frame stack. */ | |
105 | ||
106 | static void | |
107 | remove_dummy_frame (struct dummy_frame **dummy_ptr) | |
108 | { | |
109 | struct dummy_frame *dummy = *dummy_ptr; | |
110 | ||
111 | while (dummy->dtor_list != NULL) | |
112 | { | |
113 | struct dummy_frame_dtor_list *list = dummy->dtor_list; | |
114 | ||
115 | dummy->dtor_list = list->next; | |
116 | list->dtor (list->dtor_data, 0); | |
117 | xfree (list); | |
118 | } | |
119 | ||
120 | *dummy_ptr = dummy->next; | |
121 | discard_infcall_suspend_state (dummy->caller_state); | |
122 | xfree (dummy); | |
123 | } | |
124 | ||
125 | /* Delete any breakpoint B which is a momentary breakpoint for return from | |
126 | inferior call matching DUMMY_VOIDP. */ | |
127 | ||
128 | static int | |
129 | pop_dummy_frame_bpt (struct breakpoint *b, void *dummy_voidp) | |
130 | { | |
131 | struct dummy_frame *dummy = (struct dummy_frame *) dummy_voidp; | |
132 | ||
133 | if (b->thread == dummy->id.thread->global_num | |
134 | && b->disposition == disp_del && frame_id_eq (b->frame_id, dummy->id.id)) | |
135 | { | |
136 | while (b->related_breakpoint != b) | |
137 | delete_breakpoint (b->related_breakpoint); | |
138 | ||
139 | delete_breakpoint (b); | |
140 | ||
141 | /* Stop the traversal. */ | |
142 | return 1; | |
143 | } | |
144 | ||
145 | /* Continue the traversal. */ | |
146 | return 0; | |
147 | } | |
148 | ||
149 | /* Pop *DUMMY_PTR, restoring program state to that before the | |
150 | frame was created. */ | |
151 | ||
152 | static void | |
153 | pop_dummy_frame (struct dummy_frame **dummy_ptr) | |
154 | { | |
155 | struct dummy_frame *dummy = *dummy_ptr; | |
156 | ||
157 | gdb_assert (dummy->id.thread == inferior_thread ()); | |
158 | ||
159 | while (dummy->dtor_list != NULL) | |
160 | { | |
161 | struct dummy_frame_dtor_list *list = dummy->dtor_list; | |
162 | ||
163 | dummy->dtor_list = list->next; | |
164 | list->dtor (list->dtor_data, 1); | |
165 | xfree (list); | |
166 | } | |
167 | ||
168 | restore_infcall_suspend_state (dummy->caller_state); | |
169 | ||
170 | iterate_over_breakpoints (pop_dummy_frame_bpt, dummy); | |
171 | ||
172 | /* restore_infcall_control_state frees inf_state, | |
173 | all that remains is to pop *dummy_ptr. */ | |
174 | *dummy_ptr = dummy->next; | |
175 | xfree (dummy); | |
176 | ||
177 | /* We've made right mess of GDB's local state, just discard | |
178 | everything. */ | |
179 | reinit_frame_cache (); | |
180 | } | |
181 | ||
182 | /* Look up DUMMY_ID. | |
183 | Return NULL if not found. */ | |
184 | ||
185 | static struct dummy_frame ** | |
186 | lookup_dummy_frame (struct dummy_frame_id *dummy_id) | |
187 | { | |
188 | struct dummy_frame **dp; | |
189 | ||
190 | for (dp = &dummy_frame_stack; *dp != NULL; dp = &(*dp)->next) | |
191 | { | |
192 | if (dummy_frame_id_eq (&(*dp)->id, dummy_id)) | |
193 | return dp; | |
194 | } | |
195 | ||
196 | return NULL; | |
197 | } | |
198 | ||
199 | /* Find the dummy frame by DUMMY_ID and THREAD, and pop it, restoring | |
200 | program state to that before the frame was created. | |
201 | On return reinit_frame_cache has been called. | |
202 | If the frame isn't found, flag an internal error. */ | |
203 | ||
204 | void | |
205 | dummy_frame_pop (frame_id dummy_id, thread_info *thread) | |
206 | { | |
207 | struct dummy_frame **dp; | |
208 | struct dummy_frame_id id = { dummy_id, thread }; | |
209 | ||
210 | dp = lookup_dummy_frame (&id); | |
211 | gdb_assert (dp != NULL); | |
212 | ||
213 | pop_dummy_frame (dp); | |
214 | } | |
215 | ||
216 | /* Find the dummy frame by DUMMY_ID and PTID and drop it. Do nothing | |
217 | if it is not found. Do not restore its state into inferior, just | |
218 | free its memory. */ | |
219 | ||
220 | void | |
221 | dummy_frame_discard (struct frame_id dummy_id, thread_info *thread) | |
222 | { | |
223 | struct dummy_frame **dp; | |
224 | struct dummy_frame_id id = { dummy_id, thread }; | |
225 | ||
226 | dp = lookup_dummy_frame (&id); | |
227 | if (dp) | |
228 | remove_dummy_frame (dp); | |
229 | } | |
230 | ||
231 | /* See dummy-frame.h. */ | |
232 | ||
233 | void | |
234 | register_dummy_frame_dtor (frame_id dummy_id, thread_info *thread, | |
235 | dummy_frame_dtor_ftype *dtor, void *dtor_data) | |
236 | { | |
237 | struct dummy_frame_id id = { dummy_id, thread }; | |
238 | struct dummy_frame **dp, *d; | |
239 | struct dummy_frame_dtor_list *list; | |
240 | ||
241 | dp = lookup_dummy_frame (&id); | |
242 | gdb_assert (dp != NULL); | |
243 | d = *dp; | |
244 | list = XNEW (struct dummy_frame_dtor_list); | |
245 | list->next = d->dtor_list; | |
246 | d->dtor_list = list; | |
247 | list->dtor = dtor; | |
248 | list->dtor_data = dtor_data; | |
249 | } | |
250 | ||
251 | /* See dummy-frame.h. */ | |
252 | ||
253 | int | |
254 | find_dummy_frame_dtor (dummy_frame_dtor_ftype *dtor, void *dtor_data) | |
255 | { | |
256 | struct dummy_frame *d; | |
257 | ||
258 | for (d = dummy_frame_stack; d != NULL; d = d->next) | |
259 | { | |
260 | struct dummy_frame_dtor_list *list; | |
261 | ||
262 | for (list = d->dtor_list; list != NULL; list = list->next) | |
263 | if (list->dtor == dtor && list->dtor_data == dtor_data) | |
264 | return 1; | |
265 | } | |
266 | return 0; | |
267 | } | |
268 | ||
269 | /* There may be stale dummy frames, perhaps left over from when an uncaught | |
270 | longjmp took us out of a function that was called by the debugger. Clean | |
271 | them up at least once whenever we start a new inferior. */ | |
272 | ||
273 | static void | |
274 | cleanup_dummy_frames (struct target_ops *target, int from_tty) | |
275 | { | |
276 | while (dummy_frame_stack != NULL) | |
277 | remove_dummy_frame (&dummy_frame_stack); | |
278 | } | |
279 | ||
280 | /* Return the dummy frame cache, it contains both the ID, and a | |
281 | pointer to the regcache. */ | |
282 | struct dummy_frame_cache | |
283 | { | |
284 | struct frame_id this_id; | |
285 | readonly_detached_regcache *prev_regcache; | |
286 | }; | |
287 | ||
288 | static int | |
289 | dummy_frame_sniffer (const struct frame_unwind *self, | |
290 | struct frame_info *this_frame, | |
291 | void **this_prologue_cache) | |
292 | { | |
293 | /* When unwinding a normal frame, the stack structure is determined | |
294 | by analyzing the frame's function's code (be it using brute force | |
295 | prologue analysis, or the dwarf2 CFI). In the case of a dummy | |
296 | frame, that simply isn't possible. The PC is either the program | |
297 | entry point, or some random address on the stack. Trying to use | |
298 | that PC to apply standard frame ID unwind techniques is just | |
299 | asking for trouble. */ | |
300 | ||
301 | /* Don't bother unless there is at least one dummy frame. */ | |
302 | if (dummy_frame_stack != NULL) | |
303 | { | |
304 | struct dummy_frame *dummyframe; | |
305 | /* Use an architecture specific method to extract this frame's | |
306 | dummy ID, assuming it is a dummy frame. */ | |
307 | struct frame_id this_id | |
308 | = gdbarch_dummy_id (get_frame_arch (this_frame), this_frame); | |
309 | struct dummy_frame_id dummy_id = { this_id, inferior_thread () }; | |
310 | ||
311 | /* Use that ID to find the corresponding cache entry. */ | |
312 | for (dummyframe = dummy_frame_stack; | |
313 | dummyframe != NULL; | |
314 | dummyframe = dummyframe->next) | |
315 | { | |
316 | if (dummy_frame_id_eq (&dummyframe->id, &dummy_id)) | |
317 | { | |
318 | struct dummy_frame_cache *cache; | |
319 | ||
320 | cache = FRAME_OBSTACK_ZALLOC (struct dummy_frame_cache); | |
321 | cache->prev_regcache = get_infcall_suspend_state_regcache | |
322 | (dummyframe->caller_state); | |
323 | cache->this_id = this_id; | |
324 | (*this_prologue_cache) = cache; | |
325 | return 1; | |
326 | } | |
327 | } | |
328 | } | |
329 | return 0; | |
330 | } | |
331 | ||
332 | /* Given a call-dummy dummy-frame, return the registers. Here the | |
333 | register value is taken from the local copy of the register buffer. */ | |
334 | ||
335 | static struct value * | |
336 | dummy_frame_prev_register (struct frame_info *this_frame, | |
337 | void **this_prologue_cache, | |
338 | int regnum) | |
339 | { | |
340 | struct dummy_frame_cache *cache | |
341 | = (struct dummy_frame_cache *) *this_prologue_cache; | |
342 | struct gdbarch *gdbarch = get_frame_arch (this_frame); | |
343 | struct value *reg_val; | |
344 | ||
345 | /* The dummy-frame sniffer always fills in the cache. */ | |
346 | gdb_assert (cache != NULL); | |
347 | ||
348 | /* Describe the register's location. Generic dummy frames always | |
349 | have the register value in an ``expression''. */ | |
350 | reg_val = value_zero (register_type (gdbarch, regnum), not_lval); | |
351 | ||
352 | /* Use the regcache_cooked_read() method so that it, on the fly, | |
353 | constructs either a raw or pseudo register from the raw | |
354 | register cache. */ | |
355 | cache->prev_regcache->cooked_read (regnum, | |
356 | value_contents_writeable (reg_val)); | |
357 | return reg_val; | |
358 | } | |
359 | ||
360 | /* Assuming that THIS_FRAME is a dummy, return its ID. That ID is | |
361 | determined by examining the NEXT frame's unwound registers using | |
362 | the method dummy_id(). As a side effect, THIS dummy frame's | |
363 | dummy cache is located and saved in THIS_PROLOGUE_CACHE. */ | |
364 | ||
365 | static void | |
366 | dummy_frame_this_id (struct frame_info *this_frame, | |
367 | void **this_prologue_cache, | |
368 | struct frame_id *this_id) | |
369 | { | |
370 | /* The dummy-frame sniffer always fills in the cache. */ | |
371 | struct dummy_frame_cache *cache | |
372 | = (struct dummy_frame_cache *) *this_prologue_cache; | |
373 | ||
374 | gdb_assert (cache != NULL); | |
375 | (*this_id) = cache->this_id; | |
376 | } | |
377 | ||
378 | const struct frame_unwind dummy_frame_unwind = | |
379 | { | |
380 | DUMMY_FRAME, | |
381 | default_frame_unwind_stop_reason, | |
382 | dummy_frame_this_id, | |
383 | dummy_frame_prev_register, | |
384 | NULL, | |
385 | dummy_frame_sniffer, | |
386 | }; | |
387 | ||
388 | /* See dummy-frame.h. */ | |
389 | ||
390 | struct frame_id | |
391 | default_dummy_id (struct gdbarch *gdbarch, struct frame_info *this_frame) | |
392 | { | |
393 | CORE_ADDR sp, pc; | |
394 | ||
395 | sp = get_frame_sp (this_frame); | |
396 | pc = get_frame_pc (this_frame); | |
397 | return frame_id_build (sp, pc); | |
398 | } | |
399 | ||
400 | static void | |
401 | fprint_dummy_frames (struct ui_file *file) | |
402 | { | |
403 | struct dummy_frame *s; | |
404 | ||
405 | for (s = dummy_frame_stack; s != NULL; s = s->next) | |
406 | { | |
407 | gdb_print_host_address (s, file); | |
408 | fprintf_unfiltered (file, ":"); | |
409 | fprintf_unfiltered (file, " id="); | |
410 | fprint_frame_id (file, s->id.id); | |
411 | fprintf_unfiltered (file, ", ptid=%s", | |
412 | target_pid_to_str (s->id.thread->ptid).c_str ()); | |
413 | fprintf_unfiltered (file, "\n"); | |
414 | } | |
415 | } | |
416 | ||
417 | static void | |
418 | maintenance_print_dummy_frames (const char *args, int from_tty) | |
419 | { | |
420 | if (args == NULL) | |
421 | fprint_dummy_frames (gdb_stdout); | |
422 | else | |
423 | { | |
424 | stdio_file file; | |
425 | ||
426 | if (!file.open (args, "w")) | |
427 | perror_with_name (_("maintenance print dummy-frames")); | |
428 | fprint_dummy_frames (&file); | |
429 | } | |
430 | } | |
431 | ||
432 | void | |
433 | _initialize_dummy_frame (void) | |
434 | { | |
435 | add_cmd ("dummy-frames", class_maintenance, maintenance_print_dummy_frames, | |
436 | _("Print the contents of the internal dummy-frame stack."), | |
437 | &maintenanceprintlist); | |
438 | ||
439 | gdb::observers::inferior_created.attach (cleanup_dummy_frames); | |
440 | } |