1 /* Code dealing with dummy stack frames, for GDB, the GNU debugger.
3 Copyright (C) 1986-2004, 2007-2012 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 "gdb_assert.h"
27 #include "frame-unwind.h"
30 #include "gdb_string.h"
32 #include "gdbthread.h"
34 /* Dummy frame. This saves the processor state just prior to setting
35 up the inferior function call. Older targets save the registers
36 on the target stack (but that really slows down function calls). */
40 struct dummy_frame
*next
;
41 /* This frame's ID. Must match the value returned by
44 /* The caller's state prior to the call. */
45 struct infcall_suspend_state
*caller_state
;
48 static struct dummy_frame
*dummy_frame_stack
= NULL
;
50 /* Function: deprecated_pc_in_call_dummy (pc)
52 Return non-zero if the PC falls in a dummy frame created by gdb for
53 an inferior call. The code below which allows gdbarch_decr_pc_after_break
54 is for infrun.c, which may give the function a PC without that
57 FIXME: cagney/2002-11-23: This is silly. Surely "infrun.c" can
58 figure out what the real PC (as in the resume address) is BEFORE
59 calling this function.
61 NOTE: cagney/2004-08-02: I'm pretty sure that, with the introduction of
62 infrun.c:adjust_pc_after_break (thanks), this function is now
63 always called with a correctly adjusted PC!
65 NOTE: cagney/2004-08-02: Code should not need to call this. */
68 deprecated_pc_in_call_dummy (struct gdbarch
*gdbarch
, CORE_ADDR pc
)
70 struct dummy_frame
*dummyframe
;
72 for (dummyframe
= dummy_frame_stack
;
74 dummyframe
= dummyframe
->next
)
76 if ((pc
>= dummyframe
->id
.code_addr
)
77 && (pc
<= dummyframe
->id
.code_addr
78 + gdbarch_decr_pc_after_break (gdbarch
)))
84 /* Push the caller's state, along with the dummy frame info, onto the
88 dummy_frame_push (struct infcall_suspend_state
*caller_state
,
89 const struct frame_id
*dummy_id
)
91 struct dummy_frame
*dummy_frame
;
93 dummy_frame
= XZALLOC (struct dummy_frame
);
94 dummy_frame
->caller_state
= caller_state
;
95 dummy_frame
->id
= (*dummy_id
);
96 dummy_frame
->next
= dummy_frame_stack
;
97 dummy_frame_stack
= dummy_frame
;
100 /* Remove *DUMMY_PTR from the dummy frame stack. */
103 remove_dummy_frame (struct dummy_frame
**dummy_ptr
)
105 struct dummy_frame
*dummy
= *dummy_ptr
;
107 *dummy_ptr
= dummy
->next
;
108 discard_infcall_suspend_state (dummy
->caller_state
);
112 /* Delete any breakpoint B which is a momentary breakpoint for return from
113 inferior call matching DUMMY_VOIDP. */
116 pop_dummy_frame_bpt (struct breakpoint
*b
, void *dummy_voidp
)
118 struct dummy_frame
*dummy
= dummy_voidp
;
120 if (b
->thread
== pid_to_thread_id (inferior_ptid
)
121 && b
->disposition
== disp_del
&& frame_id_eq (b
->frame_id
, dummy
->id
))
123 while (b
->related_breakpoint
!= b
)
124 delete_breakpoint (b
->related_breakpoint
);
126 delete_breakpoint (b
);
128 /* Stop the traversal. */
132 /* Continue the traversal. */
136 /* Pop *DUMMY_PTR, restoring program state to that before the
137 frame was created. */
140 pop_dummy_frame (struct dummy_frame
**dummy_ptr
)
142 struct dummy_frame
*dummy
= *dummy_ptr
;
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 frame_id dummy_id
)
164 struct dummy_frame
**dp
;
166 for (dp
= &dummy_frame_stack
; *dp
!= NULL
; dp
= &(*dp
)->next
)
168 if (frame_id_eq ((*dp
)->id
, dummy_id
))
175 /* Pop the dummy frame DUMMY_ID, restoring program state to that before the
177 On return reinit_frame_cache has been called.
178 If the frame isn't found, flag an internal error.
180 NOTE: This can only pop the one frame, even if it is in the middle of the
181 stack, because the other frames may be for different threads, and there's
182 currently no way to tell which stack frame is for which thread. */
185 dummy_frame_pop (struct frame_id dummy_id
)
187 struct dummy_frame
**dp
;
189 dp
= lookup_dummy_frame (dummy_id
);
190 gdb_assert (dp
!= NULL
);
192 pop_dummy_frame (dp
);
195 /* Drop dummy frame DUMMY_ID. Do nothing if it is not found. Do not restore
196 its state into inferior, just free its memory. */
199 dummy_frame_discard (struct frame_id dummy_id
)
201 struct dummy_frame
**dp
;
203 dp
= lookup_dummy_frame (dummy_id
);
205 remove_dummy_frame (dp
);
208 /* There may be stale dummy frames, perhaps left over from when an uncaught
209 longjmp took us out of a function that was called by the debugger. Clean
210 them up at least once whenever we start a new inferior. */
213 cleanup_dummy_frames (struct target_ops
*target
, int from_tty
)
215 while (dummy_frame_stack
!= NULL
)
216 remove_dummy_frame (&dummy_frame_stack
);
219 /* Return the dummy frame cache, it contains both the ID, and a
220 pointer to the regcache. */
221 struct dummy_frame_cache
223 struct frame_id this_id
;
224 struct regcache
*prev_regcache
;
228 dummy_frame_sniffer (const struct frame_unwind
*self
,
229 struct frame_info
*this_frame
,
230 void **this_prologue_cache
)
232 struct dummy_frame
*dummyframe
;
233 struct frame_id this_id
;
235 /* When unwinding a normal frame, the stack structure is determined
236 by analyzing the frame's function's code (be it using brute force
237 prologue analysis, or the dwarf2 CFI). In the case of a dummy
238 frame, that simply isn't possible. The PC is either the program
239 entry point, or some random address on the stack. Trying to use
240 that PC to apply standard frame ID unwind techniques is just
241 asking for trouble. */
243 /* Don't bother unless there is at least one dummy frame. */
244 if (dummy_frame_stack
!= NULL
)
246 /* Use an architecture specific method to extract this frame's
247 dummy ID, assuming it is a dummy frame. */
248 this_id
= gdbarch_dummy_id (get_frame_arch (this_frame
), this_frame
);
250 /* Use that ID to find the corresponding cache entry. */
251 for (dummyframe
= dummy_frame_stack
;
253 dummyframe
= dummyframe
->next
)
255 if (frame_id_eq (dummyframe
->id
, this_id
))
257 struct dummy_frame_cache
*cache
;
259 cache
= FRAME_OBSTACK_ZALLOC (struct dummy_frame_cache
);
260 cache
->prev_regcache
= get_infcall_suspend_state_regcache
261 (dummyframe
->caller_state
);
262 cache
->this_id
= this_id
;
263 (*this_prologue_cache
) = cache
;
271 /* Given a call-dummy dummy-frame, return the registers. Here the
272 register value is taken from the local copy of the register buffer. */
274 static struct value
*
275 dummy_frame_prev_register (struct frame_info
*this_frame
,
276 void **this_prologue_cache
,
279 struct dummy_frame_cache
*cache
= (*this_prologue_cache
);
280 struct gdbarch
*gdbarch
= get_frame_arch (this_frame
);
281 struct value
*reg_val
;
283 /* The dummy-frame sniffer always fills in the cache. */
284 gdb_assert (cache
!= NULL
);
286 /* Describe the register's location. Generic dummy frames always
287 have the register value in an ``expression''. */
288 reg_val
= value_zero (register_type (gdbarch
, regnum
), not_lval
);
290 /* Use the regcache_cooked_read() method so that it, on the fly,
291 constructs either a raw or pseudo register from the raw
293 regcache_cooked_read (cache
->prev_regcache
, regnum
,
294 value_contents_writeable (reg_val
));
298 /* Assuming that THIS_FRAME is a dummy, return its ID. That ID is
299 determined by examining the NEXT frame's unwound registers using
300 the method dummy_id(). As a side effect, THIS dummy frame's
301 dummy cache is located and saved in THIS_PROLOGUE_CACHE. */
304 dummy_frame_this_id (struct frame_info
*this_frame
,
305 void **this_prologue_cache
,
306 struct frame_id
*this_id
)
308 /* The dummy-frame sniffer always fills in the cache. */
309 struct dummy_frame_cache
*cache
= (*this_prologue_cache
);
311 gdb_assert (cache
!= NULL
);
312 (*this_id
) = cache
->this_id
;
315 const struct frame_unwind dummy_frame_unwind
=
318 default_frame_unwind_stop_reason
,
320 dummy_frame_prev_register
,
326 fprint_dummy_frames (struct ui_file
*file
)
328 struct dummy_frame
*s
;
330 for (s
= dummy_frame_stack
; s
!= NULL
; s
= s
->next
)
332 gdb_print_host_address (s
, file
);
333 fprintf_unfiltered (file
, ":");
334 fprintf_unfiltered (file
, " id=");
335 fprint_frame_id (file
, s
->id
);
336 fprintf_unfiltered (file
, "\n");
341 maintenance_print_dummy_frames (char *args
, int from_tty
)
344 fprint_dummy_frames (gdb_stdout
);
347 struct cleanup
*cleanups
;
348 struct ui_file
*file
= gdb_fopen (args
, "w");
351 perror_with_name (_("maintenance print dummy-frames"));
352 cleanups
= make_cleanup_ui_file_delete (file
);
353 fprint_dummy_frames (file
);
354 do_cleanups (cleanups
);
358 extern void _initialize_dummy_frame (void);
361 _initialize_dummy_frame (void)
363 add_cmd ("dummy-frames", class_maintenance
, maintenance_print_dummy_frames
,
364 _("Print the contents of the internal dummy-frame stack."),
365 &maintenanceprintlist
);
367 observer_attach_inferior_created (cleanup_dummy_frames
);