1 /* Code dealing with dummy stack frames, for GDB, the GNU debugger.
3 Copyright 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994,
4 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002 Free Software
7 This file is part of GDB.
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 59 Temple Place - Suite 330,
22 Boston, MA 02111-1307, USA. */
26 #include "dummy-frame.h"
30 #include "gdb_assert.h"
31 #include "frame-unwind.h"
35 static void dummy_frame_this_id (struct frame_info
*next_frame
,
36 void **this_prologue_cache
,
37 struct frame_id
*this_id
);
39 static int pc_in_dummy_frame (CORE_ADDR pc
);
41 /* Dummy frame. This saves the processor state just prior to setting
42 up the inferior function call. Older targets save the registers
43 on the target stack (but that really slows down function calls). */
47 struct dummy_frame
*next
;
49 /* These values belong to the caller (the previous frame, the frame
50 that this unwinds back to). */
56 struct regcache
*regcache
;
58 /* Address range of the call dummy code. Look for PC in the range
59 [LO..HI) (after allowing for DECR_PC_AFTER_BREAK). */
64 static struct dummy_frame
*dummy_frame_stack
= NULL
;
66 /* Function: find_dummy_frame(pc, fp, sp)
68 Search the stack of dummy frames for one matching the given PC and
69 FP/SP. Unlike pc_in_dummy_frame(), this function doesn't need to
70 adjust for DECR_PC_AFTER_BREAK. This is because it is only legal
71 to call this function after the PC has been adjusted. */
73 static struct dummy_frame
*
74 find_dummy_frame (CORE_ADDR pc
, CORE_ADDR fp
)
76 struct dummy_frame
*dummyframe
;
78 for (dummyframe
= dummy_frame_stack
; dummyframe
!= NULL
;
79 dummyframe
= dummyframe
->next
)
81 /* Does the PC fall within the dummy frame's breakpoint
82 instruction. If not, discard this one. */
83 if (!(pc
>= dummyframe
->call_lo
&& pc
< dummyframe
->call_hi
))
85 /* Does the FP match? */
86 if (dummyframe
->top
!= 0)
88 /* If the target architecture explicitly saved the
89 top-of-stack before the inferior function call, assume
90 that that same architecture will always pass in an FP
91 (frame base) value that eactly matches that saved TOS.
92 Don't check the saved SP and SP as they can lead to false
94 if (fp
!= dummyframe
->top
)
99 /* An older target that hasn't explicitly or implicitly
100 saved the dummy frame's top-of-stack. Try matching the
101 FP against the saved SP and FP. NOTE: If you're trying
102 to fix a problem with GDB not correctly finding a dummy
103 frame, check the comments that go with FRAME_ALIGN() and
104 UNWIND_DUMMY_ID(). */
105 if (fp
!= dummyframe
->fp
&& fp
!= dummyframe
->sp
)
108 /* The FP matches this dummy frame. */
116 deprecated_find_dummy_frame_regcache (CORE_ADDR pc
, CORE_ADDR fp
)
118 struct dummy_frame
*dummy
= find_dummy_frame (pc
, fp
);
120 return dummy
->regcache
;
126 deprecated_generic_find_dummy_frame (CORE_ADDR pc
, CORE_ADDR fp
)
128 struct regcache
*regcache
= deprecated_find_dummy_frame_regcache (pc
, fp
);
129 if (regcache
== NULL
)
131 return deprecated_grub_regcache_for_registers (regcache
);
134 /* Function: pc_in_call_dummy (pc, sp, fp)
136 Return true if the PC falls in a dummy frame created by gdb for an
137 inferior call. The code below which allows DECR_PC_AFTER_BREAK is
138 for infrun.c, which may give the function a PC without that
142 deprecated_pc_in_call_dummy (CORE_ADDR pc
, CORE_ADDR sp
, CORE_ADDR fp
)
144 return pc_in_dummy_frame (pc
);
147 /* Return non-zero if the PC falls in a dummy frame.
149 The code below which allows DECR_PC_AFTER_BREAK is for infrun.c,
150 which may give the function a PC without that subtracted out.
152 FIXME: cagney/2002-11-23: This is silly. Surely "infrun.c" can
153 figure out what the real PC (as in the resume address) is BEFORE
154 calling this function (Oh, and I'm not even sure that this function
155 is called with an decremented PC, the call to pc_in_call_dummy() in
156 that file is conditional on
157 !DEPRECATED_CALL_DUMMY_BREAKPOINT_OFFSET_P yet generic dummy
158 targets set DEPRECATED_CALL_DUMMY_BREAKPOINT_OFFSET. True?). */
161 pc_in_dummy_frame (CORE_ADDR pc
)
163 struct dummy_frame
*dummyframe
;
164 for (dummyframe
= dummy_frame_stack
;
166 dummyframe
= dummyframe
->next
)
168 if ((pc
>= dummyframe
->call_lo
)
169 && (pc
< dummyframe
->call_hi
+ DECR_PC_AFTER_BREAK
))
175 /* Function: read_register_dummy
176 Find a saved register from before GDB calls a function in the inferior */
179 deprecated_read_register_dummy (CORE_ADDR pc
, CORE_ADDR fp
, int regno
)
181 struct regcache
*dummy_regs
= deprecated_find_dummy_frame_regcache (pc
, fp
);
185 /* NOTE: cagney/2002-08-12: Replaced a call to
186 regcache_raw_read_as_address() with a call to
187 regcache_cooked_read_unsigned(). The old, ...as_address
188 function was eventually calling extract_unsigned_integer (nee
189 extract_address) to unpack the registers value. The below is
190 doing an unsigned extract so that it is functionally
191 equivalent. The read needs to be cooked as, otherwise, it
192 will never correctly return the value of a register in the
193 [NUM_REGS .. NUM_REGS+NUM_PSEUDO_REGS) range. */
195 regcache_cooked_read_unsigned (dummy_regs
, regno
, &val
);
202 /* Save all the registers on the dummy frame stack. Most ports save the
203 registers on the target stack. This results in lots of unnecessary memory
204 references, which are slow when debugging via a serial line. Instead, we
205 save all the registers internally, and never write them to the stack. The
206 registers get restored when the called function returns to the entry point,
207 where a breakpoint is laying in wait. */
210 generic_push_dummy_frame (void)
212 struct dummy_frame
*dummy_frame
;
213 CORE_ADDR fp
= get_frame_base (get_current_frame ());
215 /* check to see if there are stale dummy frames,
216 perhaps left over from when a longjump took us out of a
217 function that was called by the debugger */
219 dummy_frame
= dummy_frame_stack
;
221 if (INNER_THAN (dummy_frame
->fp
, fp
)) /* stale -- destroy! */
223 dummy_frame_stack
= dummy_frame
->next
;
224 regcache_xfree (dummy_frame
->regcache
);
226 dummy_frame
= dummy_frame_stack
;
229 dummy_frame
= dummy_frame
->next
;
231 dummy_frame
= xmalloc (sizeof (struct dummy_frame
));
232 dummy_frame
->regcache
= regcache_xmalloc (current_gdbarch
);
234 dummy_frame
->pc
= read_pc ();
235 dummy_frame
->sp
= read_sp ();
236 dummy_frame
->top
= 0;
237 dummy_frame
->fp
= fp
;
238 dummy_frame
->id
= get_frame_id (get_current_frame ());
239 regcache_cpy (dummy_frame
->regcache
, current_regcache
);
240 dummy_frame
->next
= dummy_frame_stack
;
241 dummy_frame_stack
= dummy_frame
;
245 generic_save_dummy_frame_tos (CORE_ADDR sp
)
247 dummy_frame_stack
->top
= sp
;
250 /* Record the upper/lower bounds on the address of the call dummy. */
253 generic_save_call_dummy_addr (CORE_ADDR lo
, CORE_ADDR hi
)
255 dummy_frame_stack
->call_lo
= lo
;
256 dummy_frame_stack
->call_hi
= hi
;
259 /* Restore the machine state from either the saved dummy stack or a
263 generic_pop_current_frame (void (*popper
) (struct frame_info
* frame
))
265 struct frame_info
*frame
= get_current_frame ();
266 if (get_frame_type (frame
) == DUMMY_FRAME
)
267 /* NOTE: cagney/2002-22-23: Does this ever occure? Surely a dummy
268 frame will have already been poped by the "infrun.c" code. */
269 generic_pop_dummy_frame ();
274 /* Discard the innermost dummy frame from the dummy frame stack
275 (passed in as a parameter). */
278 discard_innermost_dummy (struct dummy_frame
**stack
)
280 struct dummy_frame
*tbd
= (*stack
);
281 (*stack
) = (*stack
)->next
;
282 regcache_xfree (tbd
->regcache
);
287 generic_pop_dummy_frame (void)
289 struct dummy_frame
*dummy_frame
= dummy_frame_stack
;
291 /* FIXME: what if the first frame isn't the right one, eg..
292 because one call-by-hand function has done a longjmp into another one? */
295 error ("Can't pop dummy frame!");
296 regcache_cpy (current_regcache
, dummy_frame
->regcache
);
297 flush_cached_frames ();
299 discard_innermost_dummy (&dummy_frame_stack
);
302 /* Given a call-dummy dummy-frame, return the registers. Here the
303 register value is taken from the local copy of the register buffer. */
306 dummy_frame_prev_register (struct frame_info
*next_frame
,
307 void **this_prologue_cache
,
308 int regnum
, int *optimized
,
309 enum lval_type
*lvalp
, CORE_ADDR
*addrp
,
310 int *realnum
, void *bufferp
)
312 struct dummy_frame
*dummy
;
315 /* Call the ID method which, if at all possible, will set the
317 dummy_frame_this_id (next_frame
, this_prologue_cache
, &id
);
318 dummy
= (*this_prologue_cache
);
319 gdb_assert (dummy
!= NULL
);
321 /* Describe the register's location. Generic dummy frames always
322 have the register value in an ``expression''. */
328 /* If needed, find and return the value of the register. */
331 /* Return the actual value. */
332 /* Use the regcache_cooked_read() method so that it, on the fly,
333 constructs either a raw or pseudo register from the raw
335 regcache_cooked_read (dummy
->regcache
, regnum
, bufferp
);
339 /* Assuming that THIS frame is a dummy (remember, the NEXT and not
340 THIS frame is passed in), return the ID of THIS frame. That ID is
341 determined by examining the NEXT frame's unwound registers using
342 the method unwind_dummy_id(). As a side effect, THIS dummy frame's
343 dummy cache is located and and saved in THIS_PROLOGUE_CACHE. */
346 dummy_frame_this_id (struct frame_info
*next_frame
,
347 void **this_prologue_cache
,
348 struct frame_id
*this_id
)
350 struct dummy_frame
*dummy
= (*this_prologue_cache
);
353 (*this_id
) = dummy
->id
;
356 /* When unwinding a normal frame, the stack structure is determined
357 by analyzing the frame's function's code (be it using brute force
358 prologue analysis, or the dwarf2 CFI). In the case of a dummy
359 frame, that simply isn't possible. The The PC is either the
360 program entry point, or some random address on the stack. Trying
361 to use that PC to apply standard frame ID unwind techniques is
362 just asking for trouble. */
363 if (gdbarch_unwind_dummy_id_p (current_gdbarch
))
365 /* Use an architecture specific method to extract the prev's
366 dummy ID from the next frame. Note that this method uses
367 frame_register_unwind to obtain the register values needed to
368 determine the dummy frame's ID. */
369 (*this_id
) = gdbarch_unwind_dummy_id (current_gdbarch
, next_frame
);
371 else if (frame_relative_level (next_frame
) < 0)
373 /* We're unwinding a sentinel frame, the PC of which is pointing
374 at a stack dummy. Fake up the dummy frame's ID using the
375 same sequence as is found a traditional unwinder. Once all
376 architectures supply the unwind_dummy_id method, this code
378 (*this_id
) = frame_id_build (deprecated_read_fp (), read_pc ());
380 else if (legacy_frame_p (current_gdbarch
)
381 && get_prev_frame (next_frame
))
383 /* Things are looking seriously grim! Assume that the legacy
384 get_prev_frame code has already created THIS frame and linked
385 it in to the frame chain (a pretty bold assumption), extract
386 the ID from THIS base / pc. */
387 (*this_id
) = frame_id_build (get_frame_base (get_prev_frame (next_frame
)),
388 get_frame_pc (get_prev_frame (next_frame
)));
392 /* Ouch! We're not trying to find the innermost frame's ID yet
393 we're trying to unwind to a dummy. The architecture must
394 provide the unwind_dummy_id() method. Abandon the unwind
395 process but only after first warning the user. */
396 internal_warning (__FILE__
, __LINE__
,
397 "Missing unwind_dummy_id architecture method");
398 (*this_id
) = null_frame_id
;
401 (*this_prologue_cache
) = find_dummy_frame ((*this_id
).code_addr
,
402 (*this_id
).stack_addr
);
405 static struct frame_unwind dummy_frame_unwind
=
409 dummy_frame_prev_register
412 const struct frame_unwind
*
413 dummy_frame_sniffer (struct frame_info
*next_frame
)
415 CORE_ADDR pc
= frame_pc_unwind (next_frame
);
416 gdb_assert (DEPRECATED_USE_GENERIC_DUMMY_FRAMES
);
417 if (pc_in_dummy_frame (pc
))
418 return &dummy_frame_unwind
;
424 fprint_dummy_frames (struct ui_file
*file
)
426 struct dummy_frame
*s
;
427 for (s
= dummy_frame_stack
; s
!= NULL
; s
= s
->next
)
429 gdb_print_host_address (s
, file
);
430 fprintf_unfiltered (file
, ":");
431 fprintf_unfiltered (file
, " pc=0x%s", paddr (s
->pc
));
432 fprintf_unfiltered (file
, " fp=0x%s", paddr (s
->fp
));
433 fprintf_unfiltered (file
, " sp=0x%s", paddr (s
->sp
));
434 fprintf_unfiltered (file
, " top=0x%s", paddr (s
->top
));
435 fprintf_unfiltered (file
, " id=");
436 fprint_frame_id (file
, s
->id
);
437 fprintf_unfiltered (file
, " call_lo=0x%s", paddr (s
->call_lo
));
438 fprintf_unfiltered (file
, " call_hi=0x%s", paddr (s
->call_hi
));
439 fprintf_unfiltered (file
, "\n");
444 maintenance_print_dummy_frames (char *args
, int from_tty
)
447 fprint_dummy_frames (gdb_stdout
);
450 struct ui_file
*file
= gdb_fopen (args
, "w");
452 perror_with_name ("maintenance print dummy-frames");
453 fprint_dummy_frames (file
);
454 ui_file_delete (file
);
458 extern void _initialize_dummy_frame (void);
461 _initialize_dummy_frame (void)
463 add_cmd ("dummy-frames", class_maintenance
, maintenance_print_dummy_frames
,
464 "Print the contents of the internal dummy-frame stack.",
465 &maintenanceprintlist
);