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"
34 /* This frame's ID. Must match the value returned by
38 /* The thread this dummy_frame relates to. */
42 /* Return whether dummy_frame_id *ID1 and *ID2 are equal. */
45 dummy_frame_id_eq (struct dummy_frame_id
*id1
,
46 struct dummy_frame_id
*id2
)
48 return frame_id_eq (id1
->id
, id2
->id
) && ptid_equal (id1
->ptid
, id2
->ptid
);
51 /* Dummy frame. This saves the processor state just prior to setting
52 up the inferior function call. Older targets save the registers
53 on the target stack (but that really slows down function calls). */
57 struct dummy_frame
*next
;
59 /* An id represents a dummy frame. */
60 struct dummy_frame_id id
;
62 /* The caller's state prior to the call. */
63 struct infcall_suspend_state
*caller_state
;
65 /* If non-NULL, a destructor that is run when this dummy frame is
67 void (*dtor
) (void *data
);
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 *dummy_ptr
= dummy
->next
;
100 discard_infcall_suspend_state (dummy
->caller_state
);
104 /* Delete any breakpoint B which is a momentary breakpoint for return from
105 inferior call matching DUMMY_VOIDP. */
108 pop_dummy_frame_bpt (struct breakpoint
*b
, void *dummy_voidp
)
110 struct dummy_frame
*dummy
= dummy_voidp
;
112 if (b
->thread
== pid_to_thread_id (dummy
->id
.ptid
)
113 && b
->disposition
== disp_del
&& frame_id_eq (b
->frame_id
, dummy
->id
.id
))
115 while (b
->related_breakpoint
!= b
)
116 delete_breakpoint (b
->related_breakpoint
);
118 delete_breakpoint (b
);
120 /* Stop the traversal. */
124 /* Continue the traversal. */
128 /* Pop *DUMMY_PTR, restoring program state to that before the
129 frame was created. */
132 pop_dummy_frame (struct dummy_frame
**dummy_ptr
)
134 struct dummy_frame
*dummy
= *dummy_ptr
;
136 gdb_assert (ptid_equal (dummy
->id
.ptid
, inferior_ptid
));
138 if (dummy
->dtor
!= NULL
)
139 dummy
->dtor (dummy
->dtor_data
);
141 restore_infcall_suspend_state (dummy
->caller_state
);
143 iterate_over_breakpoints (pop_dummy_frame_bpt
, dummy
);
145 /* restore_infcall_control_state frees inf_state,
146 all that remains is to pop *dummy_ptr. */
147 *dummy_ptr
= dummy
->next
;
150 /* We've made right mess of GDB's local state, just discard
152 reinit_frame_cache ();
156 Return NULL if not found. */
158 static struct dummy_frame
**
159 lookup_dummy_frame (struct dummy_frame_id
*dummy_id
)
161 struct dummy_frame
**dp
;
163 for (dp
= &dummy_frame_stack
; *dp
!= NULL
; dp
= &(*dp
)->next
)
165 if (dummy_frame_id_eq (&(*dp
)->id
, dummy_id
))
172 /* Find the dummy frame by DUMMY_ID and PTID, and pop it, restoring
173 program state to that before the frame was created.
174 On return reinit_frame_cache has been called.
175 If the frame isn't found, flag an internal error. */
178 dummy_frame_pop (struct frame_id dummy_id
, ptid_t ptid
)
180 struct dummy_frame
**dp
;
181 struct dummy_frame_id id
= { dummy_id
, ptid
};
183 dp
= lookup_dummy_frame (&id
);
184 gdb_assert (dp
!= NULL
);
186 pop_dummy_frame (dp
);
189 /* Find the dummy frame by DUMMY_ID and PTID and drop it. Do nothing
190 if it is not found. Do not restore its state into inferior, just
194 dummy_frame_discard (struct frame_id dummy_id
, ptid_t ptid
)
196 struct dummy_frame
**dp
;
197 struct dummy_frame_id id
= { dummy_id
, ptid
};
199 dp
= lookup_dummy_frame (&id
);
201 remove_dummy_frame (dp
);
204 /* See dummy-frame.h. */
207 register_dummy_frame_dtor (struct frame_id dummy_id
, ptid_t ptid
,
208 dummy_frame_dtor_ftype
*dtor
, void *dtor_data
)
210 struct dummy_frame_id id
= { dummy_id
, ptid
};
211 struct dummy_frame
**dp
, *d
;
213 dp
= lookup_dummy_frame (&id
);
214 gdb_assert (dp
!= NULL
);
216 gdb_assert (d
->dtor
== NULL
);
218 d
->dtor_data
= dtor_data
;
221 /* See dummy-frame.h. */
224 find_dummy_frame_dtor (dummy_frame_dtor_ftype
*dtor
, void *dtor_data
)
226 struct dummy_frame
*d
;
228 for (d
= dummy_frame_stack
; d
!= NULL
; d
= d
->next
)
229 if (d
->dtor
== dtor
&& d
->dtor_data
== dtor_data
)
234 /* There may be stale dummy frames, perhaps left over from when an uncaught
235 longjmp took us out of a function that was called by the debugger. Clean
236 them up at least once whenever we start a new inferior. */
239 cleanup_dummy_frames (struct target_ops
*target
, int from_tty
)
241 while (dummy_frame_stack
!= NULL
)
242 remove_dummy_frame (&dummy_frame_stack
);
245 /* Return the dummy frame cache, it contains both the ID, and a
246 pointer to the regcache. */
247 struct dummy_frame_cache
249 struct frame_id this_id
;
250 struct regcache
*prev_regcache
;
254 dummy_frame_sniffer (const struct frame_unwind
*self
,
255 struct frame_info
*this_frame
,
256 void **this_prologue_cache
)
258 /* When unwinding a normal frame, the stack structure is determined
259 by analyzing the frame's function's code (be it using brute force
260 prologue analysis, or the dwarf2 CFI). In the case of a dummy
261 frame, that simply isn't possible. The PC is either the program
262 entry point, or some random address on the stack. Trying to use
263 that PC to apply standard frame ID unwind techniques is just
264 asking for trouble. */
266 /* Don't bother unless there is at least one dummy frame. */
267 if (dummy_frame_stack
!= NULL
)
269 struct dummy_frame
*dummyframe
;
270 /* Use an architecture specific method to extract this frame's
271 dummy ID, assuming it is a dummy frame. */
272 struct frame_id this_id
273 = gdbarch_dummy_id (get_frame_arch (this_frame
), this_frame
);
274 struct dummy_frame_id dummy_id
= { this_id
, inferior_ptid
};
276 /* Use that ID to find the corresponding cache entry. */
277 for (dummyframe
= dummy_frame_stack
;
279 dummyframe
= dummyframe
->next
)
281 if (dummy_frame_id_eq (&dummyframe
->id
, &dummy_id
))
283 struct dummy_frame_cache
*cache
;
285 cache
= FRAME_OBSTACK_ZALLOC (struct dummy_frame_cache
);
286 cache
->prev_regcache
= get_infcall_suspend_state_regcache
287 (dummyframe
->caller_state
);
288 cache
->this_id
= this_id
;
289 (*this_prologue_cache
) = cache
;
297 /* Given a call-dummy dummy-frame, return the registers. Here the
298 register value is taken from the local copy of the register buffer. */
300 static struct value
*
301 dummy_frame_prev_register (struct frame_info
*this_frame
,
302 void **this_prologue_cache
,
305 struct dummy_frame_cache
*cache
= (*this_prologue_cache
);
306 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
307 struct value
*reg_val
;
309 /* The dummy-frame sniffer always fills in the cache. */
310 gdb_assert (cache
!= NULL
);
312 /* Describe the register's location. Generic dummy frames always
313 have the register value in an ``expression''. */
314 reg_val
= value_zero (register_type (gdbarch
, regnum
), not_lval
);
316 /* Use the regcache_cooked_read() method so that it, on the fly,
317 constructs either a raw or pseudo register from the raw
319 regcache_cooked_read (cache
->prev_regcache
, regnum
,
320 value_contents_writeable (reg_val
));
324 /* Assuming that THIS_FRAME is a dummy, return its ID. That ID is
325 determined by examining the NEXT frame's unwound registers using
326 the method dummy_id(). As a side effect, THIS dummy frame's
327 dummy cache is located and saved in THIS_PROLOGUE_CACHE. */
330 dummy_frame_this_id (struct frame_info
*this_frame
,
331 void **this_prologue_cache
,
332 struct frame_id
*this_id
)
334 /* The dummy-frame sniffer always fills in the cache. */
335 struct dummy_frame_cache
*cache
= (*this_prologue_cache
);
337 gdb_assert (cache
!= NULL
);
338 (*this_id
) = cache
->this_id
;
341 const struct frame_unwind dummy_frame_unwind
=
344 default_frame_unwind_stop_reason
,
346 dummy_frame_prev_register
,
352 fprint_dummy_frames (struct ui_file
*file
)
354 struct dummy_frame
*s
;
356 for (s
= dummy_frame_stack
; s
!= NULL
; s
= s
->next
)
358 gdb_print_host_address (s
, file
);
359 fprintf_unfiltered (file
, ":");
360 fprintf_unfiltered (file
, " id=");
361 fprint_frame_id (file
, s
->id
.id
);
362 fprintf_unfiltered (file
, ", ptid=%s",
363 target_pid_to_str (s
->id
.ptid
));
364 fprintf_unfiltered (file
, "\n");
369 maintenance_print_dummy_frames (char *args
, int from_tty
)
372 fprint_dummy_frames (gdb_stdout
);
375 struct cleanup
*cleanups
;
376 struct ui_file
*file
= gdb_fopen (args
, "w");
379 perror_with_name (_("maintenance print dummy-frames"));
380 cleanups
= make_cleanup_ui_file_delete (file
);
381 fprint_dummy_frames (file
);
382 do_cleanups (cleanups
);
386 extern void _initialize_dummy_frame (void);
389 _initialize_dummy_frame (void)
391 add_cmd ("dummy-frames", class_maintenance
, maintenance_print_dummy_frames
,
392 _("Print the contents of the internal dummy-frame stack."),
393 &maintenanceprintlist
);
395 observer_attach_inferior_created (cleanup_dummy_frames
);