aboutsummaryrefslogtreecommitdiff
path: root/gdb/libunwind-frame.c
blob: d580b519a4806dad5fcd26bedb8a3a8106e7a861 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
/* Frame unwinder for frames using the libunwind library.

   Copyright (C) 2003, 2004, 2006, 2007, 2008 Free Software Foundation, Inc.

   Written by Jeff Johnston, contributed by Red Hat Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"

#include "inferior.h"
#include "frame.h"
#include "frame-base.h"
#include "frame-unwind.h"
#include "gdbcore.h"
#include "gdbtypes.h"
#include "symtab.h"
#include "objfiles.h"
#include "regcache.h"

#include <dlfcn.h>

#include "gdb_assert.h"
#include "gdb_string.h"

#include "libunwind-frame.h"

#include "complaints.h"

static int libunwind_initialized;
static struct gdbarch_data *libunwind_descr_handle;

/* Required function pointers from libunwind.  */
static int (*unw_get_reg_p) (unw_cursor_t *, unw_regnum_t, unw_word_t *);
static int (*unw_get_fpreg_p) (unw_cursor_t *, unw_regnum_t, unw_fpreg_t *);
static int (*unw_get_saveloc_p) (unw_cursor_t *, unw_regnum_t, unw_save_loc_t *);
static int (*unw_is_signal_frame_p) (unw_cursor_t *);
static int (*unw_step_p) (unw_cursor_t *);
static int (*unw_init_remote_p) (unw_cursor_t *, unw_addr_space_t, void *);
static unw_addr_space_t (*unw_create_addr_space_p) (unw_accessors_t *, int);
static void (*unw_destroy_addr_space_p) (unw_addr_space_t);
static int (*unw_search_unwind_table_p) (unw_addr_space_t, unw_word_t, unw_dyn_info_t *,
					 unw_proc_info_t *, int, void *);
static unw_word_t (*unw_find_dyn_list_p) (unw_addr_space_t, unw_dyn_info_t *,
					  void *);


struct libunwind_frame_cache
{
  CORE_ADDR base;
  CORE_ADDR func_addr;
  unw_cursor_t cursor;
  unw_addr_space_t as;
};

/* We need to qualify the function names with a platform-specific prefix
   to match the names used by the libunwind library.  The UNW_OBJ macro is
   provided by the libunwind.h header file.  */
#define STRINGIFY2(name)	#name
#define STRINGIFY(name)		STRINGIFY2(name)

#ifndef LIBUNWIND_SO
/* Use the stable ABI major version number.  `libunwind-ia64.so' is a link time
   only library, not a runtime one.  */
#define LIBUNWIND_SO "libunwind-" STRINGIFY(UNW_TARGET) ".so.7"
#endif

static char *get_reg_name = STRINGIFY(UNW_OBJ(get_reg));
static char *get_fpreg_name = STRINGIFY(UNW_OBJ(get_fpreg));
static char *get_saveloc_name = STRINGIFY(UNW_OBJ(get_save_loc));
static char *is_signal_frame_name = STRINGIFY(UNW_OBJ(is_signal_frame));
static char *step_name = STRINGIFY(UNW_OBJ(step));
static char *init_remote_name = STRINGIFY(UNW_OBJ(init_remote));
static char *create_addr_space_name = STRINGIFY(UNW_OBJ(create_addr_space));
static char *destroy_addr_space_name = STRINGIFY(UNW_OBJ(destroy_addr_space));
static char *search_unwind_table_name = STRINGIFY(UNW_OBJ(search_unwind_table));
static char *find_dyn_list_name = STRINGIFY(UNW_OBJ(find_dyn_list));

static struct libunwind_descr *
libunwind_descr (struct gdbarch *gdbarch)
{
  return gdbarch_data (gdbarch, libunwind_descr_handle);
}

static void *
libunwind_descr_init (struct gdbarch *gdbarch)
{
  struct libunwind_descr *descr = GDBARCH_OBSTACK_ZALLOC (gdbarch,
							  struct libunwind_descr);
  return descr;
}

void
libunwind_frame_set_descr (struct gdbarch *gdbarch, struct libunwind_descr *descr)
{
  struct libunwind_descr *arch_descr;

  gdb_assert (gdbarch != NULL);

  arch_descr = gdbarch_data (gdbarch, libunwind_descr_handle);

  if (arch_descr == NULL)
    {
      /* First time here.  Must initialize data area.  */
      arch_descr = libunwind_descr_init (gdbarch);
      deprecated_set_gdbarch_data (gdbarch, libunwind_descr_handle, arch_descr);
    }

  /* Copy new descriptor info into arch descriptor.  */
  arch_descr->gdb2uw = descr->gdb2uw;
  arch_descr->uw2gdb = descr->uw2gdb;
  arch_descr->is_fpreg = descr->is_fpreg;
  arch_descr->accessors = descr->accessors;
  arch_descr->special_accessors = descr->special_accessors;
}

static struct libunwind_frame_cache *
libunwind_frame_cache (struct frame_info *this_frame, void **this_cache)
{
  unw_accessors_t *acc;
  unw_addr_space_t as;
  unw_word_t fp;
  unw_regnum_t uw_sp_regnum;
  struct libunwind_frame_cache *cache;
  struct libunwind_descr *descr;
  struct gdbarch *gdbarch = get_frame_arch (this_frame);
  int i, ret;

  if (*this_cache)
    return *this_cache;

  /* Allocate a new cache.  */
  cache = FRAME_OBSTACK_ZALLOC (struct libunwind_frame_cache);

  /* We can assume we are unwinding a normal frame.  Even if this is
     for a signal trampoline, ia64 signal "trampolines" use a normal
     subroutine call to start the signal handler.  */
  cache->func_addr = get_frame_func (this_frame);
  if (cache->func_addr == 0
      && get_next_frame (this_frame)
      && get_frame_type (get_next_frame (this_frame)) == NORMAL_FRAME)
    return NULL;

  /* Get a libunwind cursor to the previous frame.
  
     We do this by initializing a cursor.  Libunwind treats a new cursor
     as the top of stack and will get the current register set via the
     libunwind register accessor.  Now, we provide the platform-specific
     accessors and we set up the register accessor to use the frame
     register unwinding interfaces so that we properly get the registers
     for the current frame rather than the top.  We then use the unw_step
     function to move the libunwind cursor back one frame.  We can later
     use this cursor to find previous registers via the unw_get_reg
     interface which will invoke libunwind's special logic.  */
  descr = libunwind_descr (gdbarch);
  acc = descr->accessors;
  as =  unw_create_addr_space_p (acc,
				 gdbarch_byte_order (gdbarch)
				 == BFD_ENDIAN_BIG
				 ? __BIG_ENDIAN
				 : __LITTLE_ENDIAN);

  unw_init_remote_p (&cache->cursor, as, this_frame);
  if (unw_step_p (&cache->cursor) < 0)
    {
      unw_destroy_addr_space_p (as);
      return NULL;
    }

  /* To get base address, get sp from previous frame.  */
  uw_sp_regnum = descr->gdb2uw (gdbarch_sp_regnum (gdbarch));
  ret = unw_get_reg_p (&cache->cursor, uw_sp_regnum, &fp);
  if (ret < 0)
    {
      unw_destroy_addr_space_p (as);
      error (_("Can't get libunwind sp register."));
    }

  cache->base = (CORE_ADDR)fp;
  cache->as = as;

  *this_cache = cache;
  return cache;
}

void
libunwind_frame_dealloc_cache (struct frame_info *self, void *this_cache)
{
  struct libunwind_frame_cache *cache = this_cache;
  if (cache->as)
    unw_destroy_addr_space_p (cache->as);
}

unw_word_t
libunwind_find_dyn_list (unw_addr_space_t as, unw_dyn_info_t *di, void *arg)
{
  return unw_find_dyn_list_p (as, di, arg);
}

static const struct frame_unwind libunwind_frame_unwind =
{
  NORMAL_FRAME,
  libunwind_frame_this_id,
  libunwind_frame_prev_register,
  NULL,
  libunwind_frame_sniffer,
  libunwind_frame_dealloc_cache,
};

/* Verify if there is sufficient libunwind information for the frame to use
   libunwind frame unwinding.  */
int
libunwind_frame_sniffer (const struct frame_unwind *self,
                         struct frame_info *this_frame, void **this_cache)
{
  unw_cursor_t cursor;
  unw_accessors_t *acc;
  unw_addr_space_t as;
  struct libunwind_descr *descr;
  struct gdbarch *gdbarch = get_frame_arch (this_frame);
  int i, ret;

  /* To test for libunwind unwind support, initialize a cursor to
     the current frame and try to back up.  We use this same method
     when setting up the frame cache (see libunwind_frame_cache()).
     If libunwind returns success for this operation, it means that
     it has found sufficient libunwind unwinding information to do so.  */

  descr = libunwind_descr (gdbarch);
  acc = descr->accessors;
  as =  unw_create_addr_space_p (acc,
				 gdbarch_byte_order (gdbarch)
				 == BFD_ENDIAN_BIG
				 ? __BIG_ENDIAN
				 : __LITTLE_ENDIAN);

  ret = unw_init_remote_p (&cursor, as, this_frame);

  if (ret < 0)
    {
      unw_destroy_addr_space_p (as);
      return 0;
    }

 
  /* Check to see if we have libunwind info by checking if we are in a 
     signal frame.  If it doesn't return an error, we have libunwind info
     and can use libunwind.  */
  ret = unw_is_signal_frame_p (&cursor);
  unw_destroy_addr_space_p (as);

  if (ret < 0)
    return 0;

  return 1;
}

void
libunwind_frame_this_id (struct frame_info *this_frame, void **this_cache,
		         struct frame_id *this_id)
{
  struct libunwind_frame_cache *cache =
    libunwind_frame_cache (this_frame, this_cache);

  if (cache != NULL)
    (*this_id) = frame_id_build (cache->base, cache->func_addr);
  else
    (*this_id) = null_frame_id;
}

struct value *
libunwind_frame_prev_register (struct frame_info *this_frame,
                               void **this_cache, int regnum)
{
  struct libunwind_frame_cache *cache =
    libunwind_frame_cache (this_frame, this_cache);
  struct gdbarch *gdbarch = get_frame_arch (this_frame);

  void *ptr;
  unw_cursor_t *c;
  unw_save_loc_t sl;
  int i, ret;
  unw_word_t intval;
  unw_fpreg_t fpval;
  unw_regnum_t uw_regnum;
  struct libunwind_descr *descr;
  struct value *val = NULL;

  if (cache == NULL)
    return frame_unwind_got_constant (this_frame, regnum, 0);
  
  /* Convert from gdb register number to libunwind register number.  */
  descr = libunwind_descr (get_frame_arch (this_frame));
  uw_regnum = descr->gdb2uw (regnum);

  gdb_assert (regnum >= 0);

  if (!target_has_registers)
    error (_("No registers."));

  if (uw_regnum < 0)
    return frame_unwind_got_constant (this_frame, regnum, 0);

  if (unw_get_saveloc_p (&cache->cursor, uw_regnum, &sl) < 0)
    return frame_unwind_got_constant (this_frame, regnum, 0);

  switch (sl.type)
    {
    case UNW_SLT_MEMORY:
      val = frame_unwind_got_memory (this_frame, regnum, sl.u.addr);
      break;

    case UNW_SLT_REG:
      val = frame_unwind_got_register (this_frame, regnum,
                                       descr->uw2gdb (sl.u.regnum));
      break;
    case UNW_SLT_NONE:
      {
        /* The register is not stored at a specific memory address nor
           inside another register.  So use libunwind to fetch the register
           value for us, and create a constant value with the result.  */
        if (descr->is_fpreg (uw_regnum))
          {
            ret = unw_get_fpreg_p (&cache->cursor, uw_regnum, &fpval);
            if (ret < 0)
              return frame_unwind_got_constant (this_frame, regnum, 0);
            val = frame_unwind_got_bytes (this_frame, regnum,
                                          (gdb_byte *) &fpval);
          }
        else
          {
            ret = unw_get_reg_p (&cache->cursor, uw_regnum, &intval);
            if (ret < 0)
              return frame_unwind_got_constant (this_frame, regnum, 0);
            val = frame_unwind_got_constant (this_frame, regnum, intval);
          }
        set_value_optimized_out (val, 1);
        break;
      }
    }

  return val;
} 

CORE_ADDR
libunwind_frame_base_address (struct frame_info *this_frame, void **this_cache)
{
  struct libunwind_frame_cache *cache =
    libunwind_frame_cache (this_frame, this_cache);

  if (cache == NULL)
    return (CORE_ADDR)NULL;
  return cache->base;
}

/* The following is a glue routine to call the libunwind unwind table
   search function to get unwind information for a specified ip address.  */ 
int
libunwind_search_unwind_table (void *as, long ip, void *di,
			       void *pi, int need_unwind_info, void *args)
{
  return unw_search_unwind_table_p (*(unw_addr_space_t *)as, (unw_word_t )ip, 
				    di, pi, need_unwind_info, args);
}

/* Verify if we are in a sigtramp frame and we can use libunwind to unwind.  */
int
libunwind_sigtramp_frame_sniffer (const struct frame_unwind *self,
                                  struct frame_info *this_frame,
                                  void **this_cache)
{
  unw_cursor_t cursor;
  unw_accessors_t *acc;
  unw_addr_space_t as;
  struct libunwind_descr *descr;
  struct gdbarch *gdbarch = get_frame_arch (this_frame);
  int i, ret;

  /* To test for libunwind unwind support, initialize a cursor to the
     current frame and try to back up.  We use this same method when
     setting up the frame cache (see libunwind_frame_cache()).  If
     libunwind returns success for this operation, it means that it
     has found sufficient libunwind unwinding information to do
     so.  */

  descr = libunwind_descr (gdbarch);
  acc = descr->accessors;
  as =  unw_create_addr_space_p (acc,
				 gdbarch_byte_order (gdbarch)
				 == BFD_ENDIAN_BIG
				 ? __BIG_ENDIAN
				 : __LITTLE_ENDIAN);

  ret = unw_init_remote_p (&cursor, as, this_frame);

  if (ret < 0)
    {
      unw_destroy_addr_space_p (as);
      return 0;
    }

  /* Check to see if we are in a signal frame.  */
  ret = unw_is_signal_frame_p (&cursor);
  unw_destroy_addr_space_p (as);
  if (ret > 0)
    return 1;

  return 0;
}

/* The following routine is for accessing special registers of the top frame.
   A special set of accessors must be given that work without frame info.
   This is used by ia64 to access the rse registers r32-r127.  While they
   are usually located at BOF, this is not always true and only the libunwind
   info can decipher where they actually are.  */
int
libunwind_get_reg_special (struct gdbarch *gdbarch, struct regcache *regcache,
			   int regnum, void *buf)
{
  unw_cursor_t cursor;
  unw_accessors_t *acc;
  unw_addr_space_t as;
  struct libunwind_descr *descr;
  int ret;
  unw_regnum_t uw_regnum;
  unw_word_t intval;
  unw_fpreg_t fpval;
  void *ptr;


  descr = libunwind_descr (gdbarch);
  acc = descr->special_accessors;
  as =  unw_create_addr_space_p (acc,
				 gdbarch_byte_order (gdbarch)
				 == BFD_ENDIAN_BIG
				 ? __BIG_ENDIAN
				 : __LITTLE_ENDIAN);

  ret = unw_init_remote_p (&cursor, as, regcache);
  if (ret < 0)
    {
      unw_destroy_addr_space_p (as);
      return -1;
    }

  uw_regnum = descr->gdb2uw (regnum);

  if (descr->is_fpreg (uw_regnum))
    {
      ret = unw_get_fpreg_p (&cursor, uw_regnum, &fpval);
      ptr = &fpval;
    }
  else
    {
      ret = unw_get_reg_p (&cursor, uw_regnum, &intval);
      ptr = &intval;
    }

  unw_destroy_addr_space_p (as);

  if (ret < 0)
    return -1;

  if (buf)
    memcpy (buf, ptr, register_size (gdbarch, regnum));

  return 0;
}
  
static int
libunwind_load (void)
{
  void *handle;

  handle = dlopen (LIBUNWIND_SO, RTLD_NOW);
  if (handle == NULL)
    return 0;

  /* Initialize pointers to the dynamic library functions we will use.  */

  unw_get_reg_p = dlsym (handle, get_reg_name);
  if (unw_get_reg_p == NULL)
    return 0;

  unw_get_fpreg_p = dlsym (handle, get_fpreg_name);
  if (unw_get_fpreg_p == NULL)
    return 0;

  unw_get_saveloc_p = dlsym (handle, get_saveloc_name);
  if (unw_get_saveloc_p == NULL)
    return 0;

  unw_is_signal_frame_p = dlsym (handle, is_signal_frame_name);
  if (unw_is_signal_frame_p == NULL)
    return 0;

  unw_step_p = dlsym (handle, step_name);
  if (unw_step_p == NULL)
    return 0;

  unw_init_remote_p = dlsym (handle, init_remote_name);
  if (unw_init_remote_p == NULL)
    return 0;

  unw_create_addr_space_p = dlsym (handle, create_addr_space_name);
  if (unw_create_addr_space_p == NULL)
    return 0;

  unw_destroy_addr_space_p = dlsym (handle, destroy_addr_space_name);
  if (unw_destroy_addr_space_p == NULL)
    return 0;

  unw_search_unwind_table_p = dlsym (handle, search_unwind_table_name);
  if (unw_search_unwind_table_p == NULL)
    return 0;

  unw_find_dyn_list_p = dlsym (handle, find_dyn_list_name);
  if (unw_find_dyn_list_p == NULL)
    return 0;
   
  return 1;
}

int
libunwind_is_initialized (void)
{
  return libunwind_initialized;
}

/* Provide a prototype to silence -Wmissing-prototypes.  */
void _initialize_libunwind_frame (void);

void
_initialize_libunwind_frame (void)
{
  libunwind_descr_handle = gdbarch_data_register_post_init (libunwind_descr_init);

  libunwind_initialized = libunwind_load ();
}