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[/] [openrisc/] [trunk/] [gnu-old/] [gdb-6.8/] [gdb/] [dwarf2-frame.c] - Blame information for rev 24

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1 24 jeremybenn
/* Frame unwinder for frames with DWARF Call Frame Information.
2
 
3
   Copyright (C) 2003, 2004, 2005, 2007, 2008 Free Software Foundation, Inc.
4
 
5
   Contributed by Mark Kettenis.
6
 
7
   This file is part of GDB.
8
 
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 3 of the License, or
12
   (at your option) any later version.
13
 
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.
18
 
19
   You should have received a copy of the GNU General Public License
20
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
21
 
22
#include "defs.h"
23
#include "dwarf2expr.h"
24
#include "elf/dwarf2.h"
25
#include "frame.h"
26
#include "frame-base.h"
27
#include "frame-unwind.h"
28
#include "gdbcore.h"
29
#include "gdbtypes.h"
30
#include "symtab.h"
31
#include "objfiles.h"
32
#include "regcache.h"
33
#include "value.h"
34
 
35
#include "gdb_assert.h"
36
#include "gdb_string.h"
37
 
38
#include "complaints.h"
39
#include "dwarf2-frame.h"
40
 
41
/* Call Frame Information (CFI).  */
42
 
43
/* Common Information Entry (CIE).  */
44
 
45
struct dwarf2_cie
46
{
47
  /* Offset into the .debug_frame section where this CIE was found.
48
     Used to identify this CIE.  */
49
  ULONGEST cie_pointer;
50
 
51
  /* Constant that is factored out of all advance location
52
     instructions.  */
53
  ULONGEST code_alignment_factor;
54
 
55
  /* Constants that is factored out of all offset instructions.  */
56
  LONGEST data_alignment_factor;
57
 
58
  /* Return address column.  */
59
  ULONGEST return_address_register;
60
 
61
  /* Instruction sequence to initialize a register set.  */
62
  gdb_byte *initial_instructions;
63
  gdb_byte *end;
64
 
65
  /* Saved augmentation, in case it's needed later.  */
66
  char *augmentation;
67
 
68
  /* Encoding of addresses.  */
69
  gdb_byte encoding;
70
 
71
  /* True if a 'z' augmentation existed.  */
72
  unsigned char saw_z_augmentation;
73
 
74
  /* True if an 'S' augmentation existed.  */
75
  unsigned char signal_frame;
76
 
77
  /* The version recorded in the CIE.  */
78
  unsigned char version;
79
 
80
  struct dwarf2_cie *next;
81
};
82
 
83
/* Frame Description Entry (FDE).  */
84
 
85
struct dwarf2_fde
86
{
87
  /* CIE for this FDE.  */
88
  struct dwarf2_cie *cie;
89
 
90
  /* First location associated with this FDE.  */
91
  CORE_ADDR initial_location;
92
 
93
  /* Number of bytes of program instructions described by this FDE.  */
94
  CORE_ADDR address_range;
95
 
96
  /* Instruction sequence.  */
97
  gdb_byte *instructions;
98
  gdb_byte *end;
99
 
100
  /* True if this FDE is read from a .eh_frame instead of a .debug_frame
101
     section.  */
102
  unsigned char eh_frame_p;
103
 
104
  struct dwarf2_fde *next;
105
};
106
 
107
static struct dwarf2_fde *dwarf2_frame_find_fde (CORE_ADDR *pc);
108
 
109
static int dwarf2_frame_adjust_regnum (struct gdbarch *gdbarch, int regnum,
110
                                       int eh_frame_p);
111
 
112
 
113
/* Structure describing a frame state.  */
114
 
115
struct dwarf2_frame_state
116
{
117
  /* Each register save state can be described in terms of a CFA slot,
118
     another register, or a location expression.  */
119
  struct dwarf2_frame_state_reg_info
120
  {
121
    struct dwarf2_frame_state_reg *reg;
122
    int num_regs;
123
 
124
    /* Used to implement DW_CFA_remember_state.  */
125
    struct dwarf2_frame_state_reg_info *prev;
126
  } regs;
127
 
128
  LONGEST cfa_offset;
129
  ULONGEST cfa_reg;
130
  gdb_byte *cfa_exp;
131
  enum {
132
    CFA_UNSET,
133
    CFA_REG_OFFSET,
134
    CFA_EXP
135
  } cfa_how;
136
 
137
  /* The PC described by the current frame state.  */
138
  CORE_ADDR pc;
139
 
140
  /* Initial register set from the CIE.
141
     Used to implement DW_CFA_restore.  */
142
  struct dwarf2_frame_state_reg_info initial;
143
 
144
  /* The information we care about from the CIE.  */
145
  LONGEST data_align;
146
  ULONGEST code_align;
147
  ULONGEST retaddr_column;
148
 
149
  /* Flags for known producer quirks.  */
150
 
151
  /* The ARM compilers, in DWARF2 mode, assume that DW_CFA_def_cfa
152
     and DW_CFA_def_cfa_offset takes a factored offset.  */
153
  int armcc_cfa_offsets_sf;
154
 
155
  /* The ARM compilers, in DWARF2 or DWARF3 mode, may assume that
156
     the CFA is defined as REG - OFFSET rather than REG + OFFSET.  */
157
  int armcc_cfa_offsets_reversed;
158
};
159
 
160
/* Store the length the expression for the CFA in the `cfa_reg' field,
161
   which is unused in that case.  */
162
#define cfa_exp_len cfa_reg
163
 
164
/* Assert that the register set RS is large enough to store gdbarch_num_regs
165
   columns.  If necessary, enlarge the register set.  */
166
 
167
static void
168
dwarf2_frame_state_alloc_regs (struct dwarf2_frame_state_reg_info *rs,
169
                               int num_regs)
170
{
171
  size_t size = sizeof (struct dwarf2_frame_state_reg);
172
 
173
  if (num_regs <= rs->num_regs)
174
    return;
175
 
176
  rs->reg = (struct dwarf2_frame_state_reg *)
177
    xrealloc (rs->reg, num_regs * size);
178
 
179
  /* Initialize newly allocated registers.  */
180
  memset (rs->reg + rs->num_regs, 0, (num_regs - rs->num_regs) * size);
181
  rs->num_regs = num_regs;
182
}
183
 
184
/* Copy the register columns in register set RS into newly allocated
185
   memory and return a pointer to this newly created copy.  */
186
 
187
static struct dwarf2_frame_state_reg *
188
dwarf2_frame_state_copy_regs (struct dwarf2_frame_state_reg_info *rs)
189
{
190
  size_t size = rs->num_regs * sizeof (struct dwarf2_frame_state_reg);
191
  struct dwarf2_frame_state_reg *reg;
192
 
193
  reg = (struct dwarf2_frame_state_reg *) xmalloc (size);
194
  memcpy (reg, rs->reg, size);
195
 
196
  return reg;
197
}
198
 
199
/* Release the memory allocated to register set RS.  */
200
 
201
static void
202
dwarf2_frame_state_free_regs (struct dwarf2_frame_state_reg_info *rs)
203
{
204
  if (rs)
205
    {
206
      dwarf2_frame_state_free_regs (rs->prev);
207
 
208
      xfree (rs->reg);
209
      xfree (rs);
210
    }
211
}
212
 
213
/* Release the memory allocated to the frame state FS.  */
214
 
215
static void
216
dwarf2_frame_state_free (void *p)
217
{
218
  struct dwarf2_frame_state *fs = p;
219
 
220
  dwarf2_frame_state_free_regs (fs->initial.prev);
221
  dwarf2_frame_state_free_regs (fs->regs.prev);
222
  xfree (fs->initial.reg);
223
  xfree (fs->regs.reg);
224
  xfree (fs);
225
}
226
 
227
 
228
/* Helper functions for execute_stack_op.  */
229
 
230
static CORE_ADDR
231
read_reg (void *baton, int reg)
232
{
233
  struct frame_info *next_frame = (struct frame_info *) baton;
234
  struct gdbarch *gdbarch = get_frame_arch (next_frame);
235
  int regnum;
236
  gdb_byte *buf;
237
 
238
  regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, reg);
239
 
240
  buf = alloca (register_size (gdbarch, regnum));
241
  frame_unwind_register (next_frame, regnum, buf);
242
 
243
  /* Convert the register to an integer.  This returns a LONGEST
244
     rather than a CORE_ADDR, but unpack_pointer does the same thing
245
     under the covers, and this makes more sense for non-pointer
246
     registers.  Maybe read_reg and the associated interfaces should
247
     deal with "struct value" instead of CORE_ADDR.  */
248
  return unpack_long (register_type (gdbarch, regnum), buf);
249
}
250
 
251
static void
252
read_mem (void *baton, gdb_byte *buf, CORE_ADDR addr, size_t len)
253
{
254
  read_memory (addr, buf, len);
255
}
256
 
257
static void
258
no_get_frame_base (void *baton, gdb_byte **start, size_t *length)
259
{
260
  internal_error (__FILE__, __LINE__,
261
                  _("Support for DW_OP_fbreg is unimplemented"));
262
}
263
 
264
static CORE_ADDR
265
no_get_tls_address (void *baton, CORE_ADDR offset)
266
{
267
  internal_error (__FILE__, __LINE__,
268
                  _("Support for DW_OP_GNU_push_tls_address is unimplemented"));
269
}
270
 
271
/* Execute the required actions for both the DW_CFA_restore and
272
DW_CFA_restore_extended instructions.  */
273
static void
274
dwarf2_restore_rule (struct gdbarch *gdbarch, ULONGEST reg_num,
275
                     struct dwarf2_frame_state *fs, int eh_frame_p)
276
{
277
  ULONGEST reg;
278
 
279
  gdb_assert (fs->initial.reg);
280
  reg = dwarf2_frame_adjust_regnum (gdbarch, reg_num, eh_frame_p);
281
  dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
282
 
283
  /* Check if this register was explicitly initialized in the
284
  CIE initial instructions.  If not, default the rule to
285
  UNSPECIFIED.  */
286
  if (reg < fs->initial.num_regs)
287
    fs->regs.reg[reg] = fs->initial.reg[reg];
288
  else
289
    fs->regs.reg[reg].how = DWARF2_FRAME_REG_UNSPECIFIED;
290
 
291
  if (fs->regs.reg[reg].how == DWARF2_FRAME_REG_UNSPECIFIED)
292
    complaint (&symfile_complaints, _("\
293
incomplete CFI data; DW_CFA_restore unspecified\n\
294
register %s (#%d) at 0x%s"),
295
                       gdbarch_register_name
296
                       (gdbarch, gdbarch_dwarf2_reg_to_regnum (gdbarch, reg)),
297
                       gdbarch_dwarf2_reg_to_regnum (gdbarch, reg),
298
                       paddr (fs->pc));
299
}
300
 
301
static CORE_ADDR
302
execute_stack_op (gdb_byte *exp, ULONGEST len,
303
                  struct frame_info *next_frame, CORE_ADDR initial)
304
{
305
  struct dwarf_expr_context *ctx;
306
  CORE_ADDR result;
307
 
308
  ctx = new_dwarf_expr_context ();
309
  ctx->baton = next_frame;
310
  ctx->read_reg = read_reg;
311
  ctx->read_mem = read_mem;
312
  ctx->get_frame_base = no_get_frame_base;
313
  ctx->get_tls_address = no_get_tls_address;
314
 
315
  dwarf_expr_push (ctx, initial);
316
  dwarf_expr_eval (ctx, exp, len);
317
  result = dwarf_expr_fetch (ctx, 0);
318
 
319
  if (ctx->in_reg)
320
    result = read_reg (next_frame, result);
321
 
322
  free_dwarf_expr_context (ctx);
323
 
324
  return result;
325
}
326
 
327
 
328
static void
329
execute_cfa_program (gdb_byte *insn_ptr, gdb_byte *insn_end,
330
                     struct frame_info *next_frame,
331
                     struct dwarf2_frame_state *fs, int eh_frame_p)
332
{
333
  CORE_ADDR pc = frame_pc_unwind (next_frame);
334
  int bytes_read;
335
  struct gdbarch *gdbarch = get_frame_arch (next_frame);
336
 
337
  while (insn_ptr < insn_end && fs->pc <= pc)
338
    {
339
      gdb_byte insn = *insn_ptr++;
340
      ULONGEST utmp, reg;
341
      LONGEST offset;
342
 
343
      if ((insn & 0xc0) == DW_CFA_advance_loc)
344
        fs->pc += (insn & 0x3f) * fs->code_align;
345
      else if ((insn & 0xc0) == DW_CFA_offset)
346
        {
347
          reg = insn & 0x3f;
348
          reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
349
          insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
350
          offset = utmp * fs->data_align;
351
          dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
352
          fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
353
          fs->regs.reg[reg].loc.offset = offset;
354
        }
355
      else if ((insn & 0xc0) == DW_CFA_restore)
356
        {
357
          reg = insn & 0x3f;
358
          dwarf2_restore_rule (gdbarch, reg, fs, eh_frame_p);
359
        }
360
      else
361
        {
362
          switch (insn)
363
            {
364
            case DW_CFA_set_loc:
365
              fs->pc = dwarf2_read_address (insn_ptr, insn_end, &bytes_read);
366
              insn_ptr += bytes_read;
367
              break;
368
 
369
            case DW_CFA_advance_loc1:
370
              utmp = extract_unsigned_integer (insn_ptr, 1);
371
              fs->pc += utmp * fs->code_align;
372
              insn_ptr++;
373
              break;
374
            case DW_CFA_advance_loc2:
375
              utmp = extract_unsigned_integer (insn_ptr, 2);
376
              fs->pc += utmp * fs->code_align;
377
              insn_ptr += 2;
378
              break;
379
            case DW_CFA_advance_loc4:
380
              utmp = extract_unsigned_integer (insn_ptr, 4);
381
              fs->pc += utmp * fs->code_align;
382
              insn_ptr += 4;
383
              break;
384
 
385
            case DW_CFA_offset_extended:
386
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
387
              reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
388
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
389
              offset = utmp * fs->data_align;
390
              dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
391
              fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
392
              fs->regs.reg[reg].loc.offset = offset;
393
              break;
394
 
395
            case DW_CFA_restore_extended:
396
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
397
              dwarf2_restore_rule (gdbarch, reg, fs, eh_frame_p);
398
              break;
399
 
400
            case DW_CFA_undefined:
401
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
402
              reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
403
              dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
404
              fs->regs.reg[reg].how = DWARF2_FRAME_REG_UNDEFINED;
405
              break;
406
 
407
            case DW_CFA_same_value:
408
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
409
              reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
410
              dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
411
              fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAME_VALUE;
412
              break;
413
 
414
            case DW_CFA_register:
415
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
416
              reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
417
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
418
              utmp = dwarf2_frame_adjust_regnum (gdbarch, utmp, eh_frame_p);
419
              dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
420
              fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_REG;
421
              fs->regs.reg[reg].loc.reg = utmp;
422
              break;
423
 
424
            case DW_CFA_remember_state:
425
              {
426
                struct dwarf2_frame_state_reg_info *new_rs;
427
 
428
                new_rs = XMALLOC (struct dwarf2_frame_state_reg_info);
429
                *new_rs = fs->regs;
430
                fs->regs.reg = dwarf2_frame_state_copy_regs (&fs->regs);
431
                fs->regs.prev = new_rs;
432
              }
433
              break;
434
 
435
            case DW_CFA_restore_state:
436
              {
437
                struct dwarf2_frame_state_reg_info *old_rs = fs->regs.prev;
438
 
439
                if (old_rs == NULL)
440
                  {
441
                    complaint (&symfile_complaints, _("\
442
bad CFI data; mismatched DW_CFA_restore_state at 0x%s"), paddr (fs->pc));
443
                  }
444
                else
445
                  {
446
                    xfree (fs->regs.reg);
447
                    fs->regs = *old_rs;
448
                    xfree (old_rs);
449
                  }
450
              }
451
              break;
452
 
453
            case DW_CFA_def_cfa:
454
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg);
455
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
456
 
457
              if (fs->armcc_cfa_offsets_sf)
458
                utmp *= fs->data_align;
459
 
460
              fs->cfa_offset = utmp;
461
              fs->cfa_how = CFA_REG_OFFSET;
462
              break;
463
 
464
            case DW_CFA_def_cfa_register:
465
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg);
466
              fs->cfa_reg = dwarf2_frame_adjust_regnum (gdbarch, fs->cfa_reg,
467
                                                        eh_frame_p);
468
              fs->cfa_how = CFA_REG_OFFSET;
469
              break;
470
 
471
            case DW_CFA_def_cfa_offset:
472
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
473
 
474
              if (fs->armcc_cfa_offsets_sf)
475
                utmp *= fs->data_align;
476
 
477
              fs->cfa_offset = utmp;
478
              /* cfa_how deliberately not set.  */
479
              break;
480
 
481
            case DW_CFA_nop:
482
              break;
483
 
484
            case DW_CFA_def_cfa_expression:
485
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_exp_len);
486
              fs->cfa_exp = insn_ptr;
487
              fs->cfa_how = CFA_EXP;
488
              insn_ptr += fs->cfa_exp_len;
489
              break;
490
 
491
            case DW_CFA_expression:
492
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
493
              reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
494
              dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
495
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
496
              fs->regs.reg[reg].loc.exp = insn_ptr;
497
              fs->regs.reg[reg].exp_len = utmp;
498
              fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_EXP;
499
              insn_ptr += utmp;
500
              break;
501
 
502
            case DW_CFA_offset_extended_sf:
503
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
504
              reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
505
              insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset);
506
              offset *= fs->data_align;
507
              dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
508
              fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
509
              fs->regs.reg[reg].loc.offset = offset;
510
              break;
511
 
512
            case DW_CFA_val_offset:
513
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
514
              dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
515
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
516
              offset = utmp * fs->data_align;
517
              fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_OFFSET;
518
              fs->regs.reg[reg].loc.offset = offset;
519
              break;
520
 
521
            case DW_CFA_val_offset_sf:
522
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
523
              dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
524
              insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset);
525
              offset *= fs->data_align;
526
              fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_OFFSET;
527
              fs->regs.reg[reg].loc.offset = offset;
528
              break;
529
 
530
            case DW_CFA_val_expression:
531
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
532
              dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
533
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
534
              fs->regs.reg[reg].loc.exp = insn_ptr;
535
              fs->regs.reg[reg].exp_len = utmp;
536
              fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_VAL_EXP;
537
              insn_ptr += utmp;
538
              break;
539
 
540
            case DW_CFA_def_cfa_sf:
541
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg);
542
              fs->cfa_reg = dwarf2_frame_adjust_regnum (gdbarch, fs->cfa_reg,
543
                                                        eh_frame_p);
544
              insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset);
545
              fs->cfa_offset = offset * fs->data_align;
546
              fs->cfa_how = CFA_REG_OFFSET;
547
              break;
548
 
549
            case DW_CFA_def_cfa_offset_sf:
550
              insn_ptr = read_sleb128 (insn_ptr, insn_end, &offset);
551
              fs->cfa_offset = offset * fs->data_align;
552
              /* cfa_how deliberately not set.  */
553
              break;
554
 
555
            case DW_CFA_GNU_window_save:
556
              /* This is SPARC-specific code, and contains hard-coded
557
                 constants for the register numbering scheme used by
558
                 GCC.  Rather than having a architecture-specific
559
                 operation that's only ever used by a single
560
                 architecture, we provide the implementation here.
561
                 Incidentally that's what GCC does too in its
562
                 unwinder.  */
563
              {
564
                struct gdbarch *gdbarch = get_frame_arch (next_frame);
565
                int size = register_size(gdbarch, 0);
566
                dwarf2_frame_state_alloc_regs (&fs->regs, 32);
567
                for (reg = 8; reg < 16; reg++)
568
                  {
569
                    fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_REG;
570
                    fs->regs.reg[reg].loc.reg = reg + 16;
571
                  }
572
                for (reg = 16; reg < 32; reg++)
573
                  {
574
                    fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
575
                    fs->regs.reg[reg].loc.offset = (reg - 16) * size;
576
                  }
577
              }
578
              break;
579
 
580
            case DW_CFA_GNU_args_size:
581
              /* Ignored.  */
582
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp);
583
              break;
584
 
585
            case DW_CFA_GNU_negative_offset_extended:
586
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &reg);
587
              reg = dwarf2_frame_adjust_regnum (gdbarch, reg, eh_frame_p);
588
              insn_ptr = read_uleb128 (insn_ptr, insn_end, &offset);
589
              offset *= fs->data_align;
590
              dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1);
591
              fs->regs.reg[reg].how = DWARF2_FRAME_REG_SAVED_OFFSET;
592
              fs->regs.reg[reg].loc.offset = -offset;
593
              break;
594
 
595
            default:
596
              internal_error (__FILE__, __LINE__, _("Unknown CFI encountered."));
597
            }
598
        }
599
    }
600
 
601
  /* Don't allow remember/restore between CIE and FDE programs.  */
602
  dwarf2_frame_state_free_regs (fs->regs.prev);
603
  fs->regs.prev = NULL;
604
}
605
 
606
 
607
/* Architecture-specific operations.  */
608
 
609
/* Per-architecture data key.  */
610
static struct gdbarch_data *dwarf2_frame_data;
611
 
612
struct dwarf2_frame_ops
613
{
614
  /* Pre-initialize the register state REG for register REGNUM.  */
615
  void (*init_reg) (struct gdbarch *, int, struct dwarf2_frame_state_reg *,
616
                    struct frame_info *);
617
 
618
  /* Check whether the frame preceding NEXT_FRAME will be a signal
619
     trampoline.  */
620
  int (*signal_frame_p) (struct gdbarch *, struct frame_info *);
621
 
622
  /* Convert .eh_frame register number to DWARF register number, or
623
     adjust .debug_frame register number.  */
624
  int (*adjust_regnum) (struct gdbarch *, int, int);
625
};
626
 
627
/* Default architecture-specific register state initialization
628
   function.  */
629
 
630
static void
631
dwarf2_frame_default_init_reg (struct gdbarch *gdbarch, int regnum,
632
                               struct dwarf2_frame_state_reg *reg,
633
                               struct frame_info *next_frame)
634
{
635
  /* If we have a register that acts as a program counter, mark it as
636
     a destination for the return address.  If we have a register that
637
     serves as the stack pointer, arrange for it to be filled with the
638
     call frame address (CFA).  The other registers are marked as
639
     unspecified.
640
 
641
     We copy the return address to the program counter, since many
642
     parts in GDB assume that it is possible to get the return address
643
     by unwinding the program counter register.  However, on ISA's
644
     with a dedicated return address register, the CFI usually only
645
     contains information to unwind that return address register.
646
 
647
     The reason we're treating the stack pointer special here is
648
     because in many cases GCC doesn't emit CFI for the stack pointer
649
     and implicitly assumes that it is equal to the CFA.  This makes
650
     some sense since the DWARF specification (version 3, draft 8,
651
     p. 102) says that:
652
 
653
     "Typically, the CFA is defined to be the value of the stack
654
     pointer at the call site in the previous frame (which may be
655
     different from its value on entry to the current frame)."
656
 
657
     However, this isn't true for all platforms supported by GCC
658
     (e.g. IBM S/390 and zSeries).  Those architectures should provide
659
     their own architecture-specific initialization function.  */
660
 
661
  if (regnum == gdbarch_pc_regnum (gdbarch))
662
    reg->how = DWARF2_FRAME_REG_RA;
663
  else if (regnum == gdbarch_sp_regnum (gdbarch))
664
    reg->how = DWARF2_FRAME_REG_CFA;
665
}
666
 
667
/* Return a default for the architecture-specific operations.  */
668
 
669
static void *
670
dwarf2_frame_init (struct obstack *obstack)
671
{
672
  struct dwarf2_frame_ops *ops;
673
 
674
  ops = OBSTACK_ZALLOC (obstack, struct dwarf2_frame_ops);
675
  ops->init_reg = dwarf2_frame_default_init_reg;
676
  return ops;
677
}
678
 
679
/* Set the architecture-specific register state initialization
680
   function for GDBARCH to INIT_REG.  */
681
 
682
void
683
dwarf2_frame_set_init_reg (struct gdbarch *gdbarch,
684
                           void (*init_reg) (struct gdbarch *, int,
685
                                             struct dwarf2_frame_state_reg *,
686
                                             struct frame_info *))
687
{
688
  struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
689
 
690
  ops->init_reg = init_reg;
691
}
692
 
693
/* Pre-initialize the register state REG for register REGNUM.  */
694
 
695
static void
696
dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
697
                       struct dwarf2_frame_state_reg *reg,
698
                       struct frame_info *next_frame)
699
{
700
  struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
701
 
702
  ops->init_reg (gdbarch, regnum, reg, next_frame);
703
}
704
 
705
/* Set the architecture-specific signal trampoline recognition
706
   function for GDBARCH to SIGNAL_FRAME_P.  */
707
 
708
void
709
dwarf2_frame_set_signal_frame_p (struct gdbarch *gdbarch,
710
                                 int (*signal_frame_p) (struct gdbarch *,
711
                                                        struct frame_info *))
712
{
713
  struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
714
 
715
  ops->signal_frame_p = signal_frame_p;
716
}
717
 
718
/* Query the architecture-specific signal frame recognizer for
719
   NEXT_FRAME.  */
720
 
721
static int
722
dwarf2_frame_signal_frame_p (struct gdbarch *gdbarch,
723
                             struct frame_info *next_frame)
724
{
725
  struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
726
 
727
  if (ops->signal_frame_p == NULL)
728
    return 0;
729
  return ops->signal_frame_p (gdbarch, next_frame);
730
}
731
 
732
/* Set the architecture-specific adjustment of .eh_frame and .debug_frame
733
   register numbers.  */
734
 
735
void
736
dwarf2_frame_set_adjust_regnum (struct gdbarch *gdbarch,
737
                                int (*adjust_regnum) (struct gdbarch *,
738
                                                      int, int))
739
{
740
  struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
741
 
742
  ops->adjust_regnum = adjust_regnum;
743
}
744
 
745
/* Translate a .eh_frame register to DWARF register, or adjust a .debug_frame
746
   register.  */
747
 
748
static int
749
dwarf2_frame_adjust_regnum (struct gdbarch *gdbarch, int regnum, int eh_frame_p)
750
{
751
  struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
752
 
753
  if (ops->adjust_regnum == NULL)
754
    return regnum;
755
  return ops->adjust_regnum (gdbarch, regnum, eh_frame_p);
756
}
757
 
758
static void
759
dwarf2_frame_find_quirks (struct dwarf2_frame_state *fs,
760
                          struct dwarf2_fde *fde)
761
{
762
  static const char *arm_idents[] = {
763
    "ARM C Compiler, ADS",
764
    "Thumb C Compiler, ADS",
765
    "ARM C++ Compiler, ADS",
766
    "Thumb C++ Compiler, ADS",
767
    "ARM/Thumb C/C++ Compiler, RVCT"
768
  };
769
  int i;
770
 
771
  struct symtab *s;
772
 
773
  s = find_pc_symtab (fs->pc);
774
  if (s == NULL || s->producer == NULL)
775
    return;
776
 
777
  for (i = 0; i < ARRAY_SIZE (arm_idents); i++)
778
    if (strncmp (s->producer, arm_idents[i], strlen (arm_idents[i])) == 0)
779
      {
780
        if (fde->cie->version == 1)
781
          fs->armcc_cfa_offsets_sf = 1;
782
 
783
        if (fde->cie->version == 1)
784
          fs->armcc_cfa_offsets_reversed = 1;
785
 
786
        /* The reversed offset problem is present in some compilers
787
           using DWARF3, but it was eventually fixed.  Check the ARM
788
           defined augmentations, which are in the format "armcc" followed
789
           by a list of one-character options.  The "+" option means
790
           this problem is fixed (no quirk needed).  If the armcc
791
           augmentation is missing, the quirk is needed.  */
792
        if (fde->cie->version == 3
793
            && (strncmp (fde->cie->augmentation, "armcc", 5) != 0
794
                || strchr (fde->cie->augmentation + 5, '+') == NULL))
795
          fs->armcc_cfa_offsets_reversed = 1;
796
 
797
        return;
798
      }
799
}
800
 
801
 
802
struct dwarf2_frame_cache
803
{
804
  /* DWARF Call Frame Address.  */
805
  CORE_ADDR cfa;
806
 
807
  /* Set if the return address column was marked as undefined.  */
808
  int undefined_retaddr;
809
 
810
  /* Saved registers, indexed by GDB register number, not by DWARF
811
     register number.  */
812
  struct dwarf2_frame_state_reg *reg;
813
 
814
  /* Return address register.  */
815
  struct dwarf2_frame_state_reg retaddr_reg;
816
};
817
 
818
static struct dwarf2_frame_cache *
819
dwarf2_frame_cache (struct frame_info *next_frame, void **this_cache)
820
{
821
  struct cleanup *old_chain;
822
  struct gdbarch *gdbarch = get_frame_arch (next_frame);
823
  const int num_regs = gdbarch_num_regs (gdbarch)
824
                       + gdbarch_num_pseudo_regs (gdbarch);
825
  struct dwarf2_frame_cache *cache;
826
  struct dwarf2_frame_state *fs;
827
  struct dwarf2_fde *fde;
828
 
829
  if (*this_cache)
830
    return *this_cache;
831
 
832
  /* Allocate a new cache.  */
833
  cache = FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_cache);
834
  cache->reg = FRAME_OBSTACK_CALLOC (num_regs, struct dwarf2_frame_state_reg);
835
 
836
  /* Allocate and initialize the frame state.  */
837
  fs = XMALLOC (struct dwarf2_frame_state);
838
  memset (fs, 0, sizeof (struct dwarf2_frame_state));
839
  old_chain = make_cleanup (dwarf2_frame_state_free, fs);
840
 
841
  /* Unwind the PC.
842
 
843
     Note that if NEXT_FRAME is never supposed to return (i.e. a call
844
     to abort), the compiler might optimize away the instruction at
845
     NEXT_FRAME's return address.  As a result the return address will
846
     point at some random instruction, and the CFI for that
847
     instruction is probably worthless to us.  GCC's unwinder solves
848
     this problem by substracting 1 from the return address to get an
849
     address in the middle of a presumed call instruction (or the
850
     instruction in the associated delay slot).  This should only be
851
     done for "normal" frames and not for resume-type frames (signal
852
     handlers, sentinel frames, dummy frames).  The function
853
     frame_unwind_address_in_block does just this.  It's not clear how
854
     reliable the method is though; there is the potential for the
855
     register state pre-call being different to that on return.  */
856
  fs->pc = frame_unwind_address_in_block (next_frame, NORMAL_FRAME);
857
 
858
  /* Find the correct FDE.  */
859
  fde = dwarf2_frame_find_fde (&fs->pc);
860
  gdb_assert (fde != NULL);
861
 
862
  /* Extract any interesting information from the CIE.  */
863
  fs->data_align = fde->cie->data_alignment_factor;
864
  fs->code_align = fde->cie->code_alignment_factor;
865
  fs->retaddr_column = fde->cie->return_address_register;
866
 
867
  /* Check for "quirks" - known bugs in producers.  */
868
  dwarf2_frame_find_quirks (fs, fde);
869
 
870
  /* First decode all the insns in the CIE.  */
871
  execute_cfa_program (fde->cie->initial_instructions,
872
                       fde->cie->end, next_frame, fs, fde->eh_frame_p);
873
 
874
  /* Save the initialized register set.  */
875
  fs->initial = fs->regs;
876
  fs->initial.reg = dwarf2_frame_state_copy_regs (&fs->regs);
877
 
878
  /* Then decode the insns in the FDE up to our target PC.  */
879
  execute_cfa_program (fde->instructions, fde->end, next_frame, fs,
880
                       fde->eh_frame_p);
881
 
882
  /* Caclulate the CFA.  */
883
  switch (fs->cfa_how)
884
    {
885
    case CFA_REG_OFFSET:
886
      cache->cfa = read_reg (next_frame, fs->cfa_reg);
887
      if (fs->armcc_cfa_offsets_reversed)
888
        cache->cfa -= fs->cfa_offset;
889
      else
890
        cache->cfa += fs->cfa_offset;
891
      break;
892
 
893
    case CFA_EXP:
894
      cache->cfa =
895
        execute_stack_op (fs->cfa_exp, fs->cfa_exp_len, next_frame, 0);
896
      break;
897
 
898
    default:
899
      internal_error (__FILE__, __LINE__, _("Unknown CFA rule."));
900
    }
901
 
902
  /* Initialize the register state.  */
903
  {
904
    int regnum;
905
 
906
    for (regnum = 0; regnum < num_regs; regnum++)
907
      dwarf2_frame_init_reg (gdbarch, regnum, &cache->reg[regnum], next_frame);
908
  }
909
 
910
  /* Go through the DWARF2 CFI generated table and save its register
911
     location information in the cache.  Note that we don't skip the
912
     return address column; it's perfectly all right for it to
913
     correspond to a real register.  If it doesn't correspond to a
914
     real register, or if we shouldn't treat it as such,
915
     gdbarch_dwarf2_reg_to_regnum should be defined to return a number outside
916
     the range [0, gdbarch_num_regs).  */
917
  {
918
    int column;         /* CFI speak for "register number".  */
919
 
920
    for (column = 0; column < fs->regs.num_regs; column++)
921
      {
922
        /* Use the GDB register number as the destination index.  */
923
        int regnum = gdbarch_dwarf2_reg_to_regnum (gdbarch, column);
924
 
925
        /* If there's no corresponding GDB register, ignore it.  */
926
        if (regnum < 0 || regnum >= num_regs)
927
          continue;
928
 
929
        /* NOTE: cagney/2003-09-05: CFI should specify the disposition
930
           of all debug info registers.  If it doesn't, complain (but
931
           not too loudly).  It turns out that GCC assumes that an
932
           unspecified register implies "same value" when CFI (draft
933
           7) specifies nothing at all.  Such a register could equally
934
           be interpreted as "undefined".  Also note that this check
935
           isn't sufficient; it only checks that all registers in the
936
           range [0 .. max column] are specified, and won't detect
937
           problems when a debug info register falls outside of the
938
           table.  We need a way of iterating through all the valid
939
           DWARF2 register numbers.  */
940
        if (fs->regs.reg[column].how == DWARF2_FRAME_REG_UNSPECIFIED)
941
          {
942
            if (cache->reg[regnum].how == DWARF2_FRAME_REG_UNSPECIFIED)
943
              complaint (&symfile_complaints, _("\
944
incomplete CFI data; unspecified registers (e.g., %s) at 0x%s"),
945
                         gdbarch_register_name (gdbarch, regnum),
946
                         paddr_nz (fs->pc));
947
          }
948
        else
949
          cache->reg[regnum] = fs->regs.reg[column];
950
      }
951
  }
952
 
953
  /* Eliminate any DWARF2_FRAME_REG_RA rules, and save the information
954
     we need for evaluating DWARF2_FRAME_REG_RA_OFFSET rules.  */
955
  {
956
    int regnum;
957
 
958
    for (regnum = 0; regnum < num_regs; regnum++)
959
      {
960
        if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA
961
            || cache->reg[regnum].how == DWARF2_FRAME_REG_RA_OFFSET)
962
          {
963
            struct dwarf2_frame_state_reg *retaddr_reg =
964
              &fs->regs.reg[fs->retaddr_column];
965
 
966
            /* It seems rather bizarre to specify an "empty" column as
967
               the return adress column.  However, this is exactly
968
               what GCC does on some targets.  It turns out that GCC
969
               assumes that the return address can be found in the
970
               register corresponding to the return address column.
971
               Incidentally, that's how we should treat a return
972
               address column specifying "same value" too.  */
973
            if (fs->retaddr_column < fs->regs.num_regs
974
                && retaddr_reg->how != DWARF2_FRAME_REG_UNSPECIFIED
975
                && retaddr_reg->how != DWARF2_FRAME_REG_SAME_VALUE)
976
              {
977
                if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA)
978
                  cache->reg[regnum] = *retaddr_reg;
979
                else
980
                  cache->retaddr_reg = *retaddr_reg;
981
              }
982
            else
983
              {
984
                if (cache->reg[regnum].how == DWARF2_FRAME_REG_RA)
985
                  {
986
                    cache->reg[regnum].loc.reg = fs->retaddr_column;
987
                    cache->reg[regnum].how = DWARF2_FRAME_REG_SAVED_REG;
988
                  }
989
                else
990
                  {
991
                    cache->retaddr_reg.loc.reg = fs->retaddr_column;
992
                    cache->retaddr_reg.how = DWARF2_FRAME_REG_SAVED_REG;
993
                  }
994
              }
995
          }
996
      }
997
  }
998
 
999
  if (fs->retaddr_column < fs->regs.num_regs
1000
      && fs->regs.reg[fs->retaddr_column].how == DWARF2_FRAME_REG_UNDEFINED)
1001
    cache->undefined_retaddr = 1;
1002
 
1003
  do_cleanups (old_chain);
1004
 
1005
  *this_cache = cache;
1006
  return cache;
1007
}
1008
 
1009
static void
1010
dwarf2_frame_this_id (struct frame_info *next_frame, void **this_cache,
1011
                      struct frame_id *this_id)
1012
{
1013
  struct dwarf2_frame_cache *cache =
1014
    dwarf2_frame_cache (next_frame, this_cache);
1015
 
1016
  if (cache->undefined_retaddr)
1017
    return;
1018
 
1019
  (*this_id) = frame_id_build (cache->cfa,
1020
                               frame_func_unwind (next_frame, NORMAL_FRAME));
1021
}
1022
 
1023
static void
1024
dwarf2_signal_frame_this_id (struct frame_info *next_frame, void **this_cache,
1025
                             struct frame_id *this_id)
1026
{
1027
  struct dwarf2_frame_cache *cache =
1028
    dwarf2_frame_cache (next_frame, this_cache);
1029
 
1030
  if (cache->undefined_retaddr)
1031
    return;
1032
 
1033
  (*this_id) = frame_id_build (cache->cfa,
1034
                               frame_func_unwind (next_frame, SIGTRAMP_FRAME));
1035
}
1036
 
1037
static void
1038
dwarf2_frame_prev_register (struct frame_info *next_frame, void **this_cache,
1039
                            int regnum, int *optimizedp,
1040
                            enum lval_type *lvalp, CORE_ADDR *addrp,
1041
                            int *realnump, gdb_byte *valuep)
1042
{
1043
  struct gdbarch *gdbarch = get_frame_arch (next_frame);
1044
  struct dwarf2_frame_cache *cache =
1045
    dwarf2_frame_cache (next_frame, this_cache);
1046
 
1047
  switch (cache->reg[regnum].how)
1048
    {
1049
    case DWARF2_FRAME_REG_UNDEFINED:
1050
      /* If CFI explicitly specified that the value isn't defined,
1051
         mark it as optimized away; the value isn't available.  */
1052
      *optimizedp = 1;
1053
      *lvalp = not_lval;
1054
      *addrp = 0;
1055
      *realnump = -1;
1056
      if (valuep)
1057
        {
1058
          /* In some cases, for example %eflags on the i386, we have
1059
             to provide a sane value, even though this register wasn't
1060
             saved.  Assume we can get it from NEXT_FRAME.  */
1061
          frame_unwind_register (next_frame, regnum, valuep);
1062
        }
1063
      break;
1064
 
1065
    case DWARF2_FRAME_REG_SAVED_OFFSET:
1066
      *optimizedp = 0;
1067
      *lvalp = lval_memory;
1068
      *addrp = cache->cfa + cache->reg[regnum].loc.offset;
1069
      *realnump = -1;
1070
      if (valuep)
1071
        {
1072
          /* Read the value in from memory.  */
1073
          read_memory (*addrp, valuep, register_size (gdbarch, regnum));
1074
        }
1075
      break;
1076
 
1077
    case DWARF2_FRAME_REG_SAVED_REG:
1078
      *optimizedp = 0;
1079
      *lvalp = lval_register;
1080
      *addrp = 0;
1081
      *realnump = gdbarch_dwarf2_reg_to_regnum
1082
                    (gdbarch, cache->reg[regnum].loc.reg);
1083
      if (valuep)
1084
        frame_unwind_register (next_frame, (*realnump), valuep);
1085
      break;
1086
 
1087
    case DWARF2_FRAME_REG_SAVED_EXP:
1088
      *optimizedp = 0;
1089
      *lvalp = lval_memory;
1090
      *addrp = execute_stack_op (cache->reg[regnum].loc.exp,
1091
                                 cache->reg[regnum].exp_len,
1092
                                 next_frame, cache->cfa);
1093
      *realnump = -1;
1094
      if (valuep)
1095
        {
1096
          /* Read the value in from memory.  */
1097
          read_memory (*addrp, valuep, register_size (gdbarch, regnum));
1098
        }
1099
      break;
1100
 
1101
    case DWARF2_FRAME_REG_SAVED_VAL_OFFSET:
1102
      *optimizedp = 0;
1103
      *lvalp = not_lval;
1104
      *addrp = 0;
1105
      *realnump = -1;
1106
      if (valuep)
1107
        store_unsigned_integer (valuep, register_size (gdbarch, regnum),
1108
                                cache->cfa + cache->reg[regnum].loc.offset);
1109
      break;
1110
 
1111
    case DWARF2_FRAME_REG_SAVED_VAL_EXP:
1112
      *optimizedp = 0;
1113
      *lvalp = not_lval;
1114
      *addrp = 0;
1115
      *realnump = -1;
1116
      if (valuep)
1117
        store_unsigned_integer (valuep, register_size (gdbarch, regnum),
1118
                                execute_stack_op (cache->reg[regnum].loc.exp,
1119
                                                  cache->reg[regnum].exp_len,
1120
                                                  next_frame, cache->cfa));
1121
      break;
1122
 
1123
    case DWARF2_FRAME_REG_UNSPECIFIED:
1124
      /* GCC, in its infinite wisdom decided to not provide unwind
1125
         information for registers that are "same value".  Since
1126
         DWARF2 (3 draft 7) doesn't define such behavior, said
1127
         registers are actually undefined (which is different to CFI
1128
         "undefined").  Code above issues a complaint about this.
1129
         Here just fudge the books, assume GCC, and that the value is
1130
         more inner on the stack.  */
1131
      *optimizedp = 0;
1132
      *lvalp = lval_register;
1133
      *addrp = 0;
1134
      *realnump = regnum;
1135
      if (valuep)
1136
        frame_unwind_register (next_frame, (*realnump), valuep);
1137
      break;
1138
 
1139
    case DWARF2_FRAME_REG_SAME_VALUE:
1140
      *optimizedp = 0;
1141
      *lvalp = lval_register;
1142
      *addrp = 0;
1143
      *realnump = regnum;
1144
      if (valuep)
1145
        frame_unwind_register (next_frame, (*realnump), valuep);
1146
      break;
1147
 
1148
    case DWARF2_FRAME_REG_CFA:
1149
      *optimizedp = 0;
1150
      *lvalp = not_lval;
1151
      *addrp = 0;
1152
      *realnump = -1;
1153
      if (valuep)
1154
        pack_long (valuep, register_type (gdbarch, regnum), cache->cfa);
1155
      break;
1156
 
1157
    case DWARF2_FRAME_REG_CFA_OFFSET:
1158
      *optimizedp = 0;
1159
      *lvalp = not_lval;
1160
      *addrp = 0;
1161
      *realnump = -1;
1162
      if (valuep)
1163
        pack_long (valuep, register_type (gdbarch, regnum),
1164
                   cache->cfa + cache->reg[regnum].loc.offset);
1165
      break;
1166
 
1167
    case DWARF2_FRAME_REG_RA_OFFSET:
1168
      *optimizedp = 0;
1169
      *lvalp = not_lval;
1170
      *addrp = 0;
1171
      *realnump = -1;
1172
      if (valuep)
1173
        {
1174
          CORE_ADDR pc = cache->reg[regnum].loc.offset;
1175
 
1176
          regnum = gdbarch_dwarf2_reg_to_regnum
1177
                     (gdbarch, cache->retaddr_reg.loc.reg);
1178
          pc += frame_unwind_register_unsigned (next_frame, regnum);
1179
          pack_long (valuep, register_type (gdbarch, regnum), pc);
1180
        }
1181
      break;
1182
 
1183
    default:
1184
      internal_error (__FILE__, __LINE__, _("Unknown register rule."));
1185
    }
1186
}
1187
 
1188
static const struct frame_unwind dwarf2_frame_unwind =
1189
{
1190
  NORMAL_FRAME,
1191
  dwarf2_frame_this_id,
1192
  dwarf2_frame_prev_register
1193
};
1194
 
1195
static const struct frame_unwind dwarf2_signal_frame_unwind =
1196
{
1197
  SIGTRAMP_FRAME,
1198
  dwarf2_signal_frame_this_id,
1199
  dwarf2_frame_prev_register
1200
};
1201
 
1202
const struct frame_unwind *
1203
dwarf2_frame_sniffer (struct frame_info *next_frame)
1204
{
1205
  /* Grab an address that is guarenteed to reside somewhere within the
1206
     function.  frame_pc_unwind(), for a no-return next function, can
1207
     end up returning something past the end of this function's body.
1208
     If the frame we're sniffing for is a signal frame whose start
1209
     address is placed on the stack by the OS, its FDE must
1210
     extend one byte before its start address or we will miss it.  */
1211
  CORE_ADDR block_addr = frame_unwind_address_in_block (next_frame,
1212
                                                        NORMAL_FRAME);
1213
  struct dwarf2_fde *fde = dwarf2_frame_find_fde (&block_addr);
1214
  if (!fde)
1215
    return NULL;
1216
 
1217
  /* On some targets, signal trampolines may have unwind information.
1218
     We need to recognize them so that we set the frame type
1219
     correctly.  */
1220
 
1221
  if (fde->cie->signal_frame
1222
      || dwarf2_frame_signal_frame_p (get_frame_arch (next_frame),
1223
                                      next_frame))
1224
    return &dwarf2_signal_frame_unwind;
1225
 
1226
  return &dwarf2_frame_unwind;
1227
}
1228
 
1229
 
1230
/* There is no explicitly defined relationship between the CFA and the
1231
   location of frame's local variables and arguments/parameters.
1232
   Therefore, frame base methods on this page should probably only be
1233
   used as a last resort, just to avoid printing total garbage as a
1234
   response to the "info frame" command.  */
1235
 
1236
static CORE_ADDR
1237
dwarf2_frame_base_address (struct frame_info *next_frame, void **this_cache)
1238
{
1239
  struct dwarf2_frame_cache *cache =
1240
    dwarf2_frame_cache (next_frame, this_cache);
1241
 
1242
  return cache->cfa;
1243
}
1244
 
1245
static const struct frame_base dwarf2_frame_base =
1246
{
1247
  &dwarf2_frame_unwind,
1248
  dwarf2_frame_base_address,
1249
  dwarf2_frame_base_address,
1250
  dwarf2_frame_base_address
1251
};
1252
 
1253
const struct frame_base *
1254
dwarf2_frame_base_sniffer (struct frame_info *next_frame)
1255
{
1256
  CORE_ADDR block_addr = frame_unwind_address_in_block (next_frame,
1257
                                                        NORMAL_FRAME);
1258
  if (dwarf2_frame_find_fde (&block_addr))
1259
    return &dwarf2_frame_base;
1260
 
1261
  return NULL;
1262
}
1263
 
1264
/* A minimal decoding of DWARF2 compilation units.  We only decode
1265
   what's needed to get to the call frame information.  */
1266
 
1267
struct comp_unit
1268
{
1269
  /* Keep the bfd convenient.  */
1270
  bfd *abfd;
1271
 
1272
  struct objfile *objfile;
1273
 
1274
  /* Linked list of CIEs for this object.  */
1275
  struct dwarf2_cie *cie;
1276
 
1277
  /* Pointer to the .debug_frame section loaded into memory.  */
1278
  gdb_byte *dwarf_frame_buffer;
1279
 
1280
  /* Length of the loaded .debug_frame section.  */
1281
  unsigned long dwarf_frame_size;
1282
 
1283
  /* Pointer to the .debug_frame section.  */
1284
  asection *dwarf_frame_section;
1285
 
1286
  /* Base for DW_EH_PE_datarel encodings.  */
1287
  bfd_vma dbase;
1288
 
1289
  /* Base for DW_EH_PE_textrel encodings.  */
1290
  bfd_vma tbase;
1291
};
1292
 
1293
const struct objfile_data *dwarf2_frame_objfile_data;
1294
 
1295
static unsigned int
1296
read_1_byte (bfd *abfd, gdb_byte *buf)
1297
{
1298
  return bfd_get_8 (abfd, buf);
1299
}
1300
 
1301
static unsigned int
1302
read_4_bytes (bfd *abfd, gdb_byte *buf)
1303
{
1304
  return bfd_get_32 (abfd, buf);
1305
}
1306
 
1307
static ULONGEST
1308
read_8_bytes (bfd *abfd, gdb_byte *buf)
1309
{
1310
  return bfd_get_64 (abfd, buf);
1311
}
1312
 
1313
static ULONGEST
1314
read_unsigned_leb128 (bfd *abfd, gdb_byte *buf, unsigned int *bytes_read_ptr)
1315
{
1316
  ULONGEST result;
1317
  unsigned int num_read;
1318
  int shift;
1319
  gdb_byte byte;
1320
 
1321
  result = 0;
1322
  shift = 0;
1323
  num_read = 0;
1324
 
1325
  do
1326
    {
1327
      byte = bfd_get_8 (abfd, (bfd_byte *) buf);
1328
      buf++;
1329
      num_read++;
1330
      result |= ((byte & 0x7f) << shift);
1331
      shift += 7;
1332
    }
1333
  while (byte & 0x80);
1334
 
1335
  *bytes_read_ptr = num_read;
1336
 
1337
  return result;
1338
}
1339
 
1340
static LONGEST
1341
read_signed_leb128 (bfd *abfd, gdb_byte *buf, unsigned int *bytes_read_ptr)
1342
{
1343
  LONGEST result;
1344
  int shift;
1345
  unsigned int num_read;
1346
  gdb_byte byte;
1347
 
1348
  result = 0;
1349
  shift = 0;
1350
  num_read = 0;
1351
 
1352
  do
1353
    {
1354
      byte = bfd_get_8 (abfd, (bfd_byte *) buf);
1355
      buf++;
1356
      num_read++;
1357
      result |= ((byte & 0x7f) << shift);
1358
      shift += 7;
1359
    }
1360
  while (byte & 0x80);
1361
 
1362
  if (shift < 8 * sizeof (result) && (byte & 0x40))
1363
    result |= -(((LONGEST)1) << shift);
1364
 
1365
  *bytes_read_ptr = num_read;
1366
 
1367
  return result;
1368
}
1369
 
1370
static ULONGEST
1371
read_initial_length (bfd *abfd, gdb_byte *buf, unsigned int *bytes_read_ptr)
1372
{
1373
  LONGEST result;
1374
 
1375
  result = bfd_get_32 (abfd, buf);
1376
  if (result == 0xffffffff)
1377
    {
1378
      result = bfd_get_64 (abfd, buf + 4);
1379
      *bytes_read_ptr = 12;
1380
    }
1381
  else
1382
    *bytes_read_ptr = 4;
1383
 
1384
  return result;
1385
}
1386
 
1387
 
1388
/* Pointer encoding helper functions.  */
1389
 
1390
/* GCC supports exception handling based on DWARF2 CFI.  However, for
1391
   technical reasons, it encodes addresses in its FDE's in a different
1392
   way.  Several "pointer encodings" are supported.  The encoding
1393
   that's used for a particular FDE is determined by the 'R'
1394
   augmentation in the associated CIE.  The argument of this
1395
   augmentation is a single byte.
1396
 
1397
   The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a
1398
   LEB128.  This is encoded in bits 0, 1 and 2.  Bit 3 encodes whether
1399
   the address is signed or unsigned.  Bits 4, 5 and 6 encode how the
1400
   address should be interpreted (absolute, relative to the current
1401
   position in the FDE, ...).  Bit 7, indicates that the address
1402
   should be dereferenced.  */
1403
 
1404
static gdb_byte
1405
encoding_for_size (unsigned int size)
1406
{
1407
  switch (size)
1408
    {
1409
    case 2:
1410
      return DW_EH_PE_udata2;
1411
    case 4:
1412
      return DW_EH_PE_udata4;
1413
    case 8:
1414
      return DW_EH_PE_udata8;
1415
    default:
1416
      internal_error (__FILE__, __LINE__, _("Unsupported address size"));
1417
    }
1418
}
1419
 
1420
static unsigned int
1421
size_of_encoded_value (gdb_byte encoding)
1422
{
1423
  if (encoding == DW_EH_PE_omit)
1424
    return 0;
1425
 
1426
  switch (encoding & 0x07)
1427
    {
1428
    case DW_EH_PE_absptr:
1429
      return TYPE_LENGTH (builtin_type_void_data_ptr);
1430
    case DW_EH_PE_udata2:
1431
      return 2;
1432
    case DW_EH_PE_udata4:
1433
      return 4;
1434
    case DW_EH_PE_udata8:
1435
      return 8;
1436
    default:
1437
      internal_error (__FILE__, __LINE__, _("Invalid or unsupported encoding"));
1438
    }
1439
}
1440
 
1441
static CORE_ADDR
1442
read_encoded_value (struct comp_unit *unit, gdb_byte encoding,
1443
                    gdb_byte *buf, unsigned int *bytes_read_ptr)
1444
{
1445
  int ptr_len = size_of_encoded_value (DW_EH_PE_absptr);
1446
  ptrdiff_t offset;
1447
  CORE_ADDR base;
1448
 
1449
  /* GCC currently doesn't generate DW_EH_PE_indirect encodings for
1450
     FDE's.  */
1451
  if (encoding & DW_EH_PE_indirect)
1452
    internal_error (__FILE__, __LINE__,
1453
                    _("Unsupported encoding: DW_EH_PE_indirect"));
1454
 
1455
  *bytes_read_ptr = 0;
1456
 
1457
  switch (encoding & 0x70)
1458
    {
1459
    case DW_EH_PE_absptr:
1460
      base = 0;
1461
      break;
1462
    case DW_EH_PE_pcrel:
1463
      base = bfd_get_section_vma (unit->abfd, unit->dwarf_frame_section);
1464
      base += (buf - unit->dwarf_frame_buffer);
1465
      break;
1466
    case DW_EH_PE_datarel:
1467
      base = unit->dbase;
1468
      break;
1469
    case DW_EH_PE_textrel:
1470
      base = unit->tbase;
1471
      break;
1472
    case DW_EH_PE_funcrel:
1473
      /* FIXME: kettenis/20040501: For now just pretend
1474
         DW_EH_PE_funcrel is equivalent to DW_EH_PE_absptr.  For
1475
         reading the initial location of an FDE it should be treated
1476
         as such, and currently that's the only place where this code
1477
         is used.  */
1478
      base = 0;
1479
      break;
1480
    case DW_EH_PE_aligned:
1481
      base = 0;
1482
      offset = buf - unit->dwarf_frame_buffer;
1483
      if ((offset % ptr_len) != 0)
1484
        {
1485
          *bytes_read_ptr = ptr_len - (offset % ptr_len);
1486
          buf += *bytes_read_ptr;
1487
        }
1488
      break;
1489
    default:
1490
      internal_error (__FILE__, __LINE__, _("Invalid or unsupported encoding"));
1491
    }
1492
 
1493
  if ((encoding & 0x07) == 0x00)
1494
    {
1495
      encoding |= encoding_for_size (ptr_len);
1496
      if (bfd_get_sign_extend_vma (unit->abfd))
1497
        encoding |= DW_EH_PE_signed;
1498
    }
1499
 
1500
  switch (encoding & 0x0f)
1501
    {
1502
    case DW_EH_PE_uleb128:
1503
      {
1504
        ULONGEST value;
1505
        gdb_byte *end_buf = buf + (sizeof (value) + 1) * 8 / 7;
1506
        *bytes_read_ptr += read_uleb128 (buf, end_buf, &value) - buf;
1507
        return base + value;
1508
      }
1509
    case DW_EH_PE_udata2:
1510
      *bytes_read_ptr += 2;
1511
      return (base + bfd_get_16 (unit->abfd, (bfd_byte *) buf));
1512
    case DW_EH_PE_udata4:
1513
      *bytes_read_ptr += 4;
1514
      return (base + bfd_get_32 (unit->abfd, (bfd_byte *) buf));
1515
    case DW_EH_PE_udata8:
1516
      *bytes_read_ptr += 8;
1517
      return (base + bfd_get_64 (unit->abfd, (bfd_byte *) buf));
1518
    case DW_EH_PE_sleb128:
1519
      {
1520
        LONGEST value;
1521
        gdb_byte *end_buf = buf + (sizeof (value) + 1) * 8 / 7;
1522
        *bytes_read_ptr += read_sleb128 (buf, end_buf, &value) - buf;
1523
        return base + value;
1524
      }
1525
    case DW_EH_PE_sdata2:
1526
      *bytes_read_ptr += 2;
1527
      return (base + bfd_get_signed_16 (unit->abfd, (bfd_byte *) buf));
1528
    case DW_EH_PE_sdata4:
1529
      *bytes_read_ptr += 4;
1530
      return (base + bfd_get_signed_32 (unit->abfd, (bfd_byte *) buf));
1531
    case DW_EH_PE_sdata8:
1532
      *bytes_read_ptr += 8;
1533
      return (base + bfd_get_signed_64 (unit->abfd, (bfd_byte *) buf));
1534
    default:
1535
      internal_error (__FILE__, __LINE__, _("Invalid or unsupported encoding"));
1536
    }
1537
}
1538
 
1539
 
1540
/* GCC uses a single CIE for all FDEs in a .debug_frame section.
1541
   That's why we use a simple linked list here.  */
1542
 
1543
static struct dwarf2_cie *
1544
find_cie (struct comp_unit *unit, ULONGEST cie_pointer)
1545
{
1546
  struct dwarf2_cie *cie = unit->cie;
1547
 
1548
  while (cie)
1549
    {
1550
      if (cie->cie_pointer == cie_pointer)
1551
        return cie;
1552
 
1553
      cie = cie->next;
1554
    }
1555
 
1556
  return NULL;
1557
}
1558
 
1559
static void
1560
add_cie (struct comp_unit *unit, struct dwarf2_cie *cie)
1561
{
1562
  cie->next = unit->cie;
1563
  unit->cie = cie;
1564
}
1565
 
1566
/* Find the FDE for *PC.  Return a pointer to the FDE, and store the
1567
   inital location associated with it into *PC.  */
1568
 
1569
static struct dwarf2_fde *
1570
dwarf2_frame_find_fde (CORE_ADDR *pc)
1571
{
1572
  struct objfile *objfile;
1573
 
1574
  ALL_OBJFILES (objfile)
1575
    {
1576
      struct dwarf2_fde *fde;
1577
      CORE_ADDR offset;
1578
 
1579
      fde = objfile_data (objfile, dwarf2_frame_objfile_data);
1580
      if (fde == NULL)
1581
        continue;
1582
 
1583
      gdb_assert (objfile->section_offsets);
1584
      offset = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));
1585
 
1586
      while (fde)
1587
        {
1588
          if (*pc >= fde->initial_location + offset
1589
              && *pc < fde->initial_location + offset + fde->address_range)
1590
            {
1591
              *pc = fde->initial_location + offset;
1592
              return fde;
1593
            }
1594
 
1595
          fde = fde->next;
1596
        }
1597
    }
1598
 
1599
  return NULL;
1600
}
1601
 
1602
static void
1603
add_fde (struct comp_unit *unit, struct dwarf2_fde *fde)
1604
{
1605
  fde->next = objfile_data (unit->objfile, dwarf2_frame_objfile_data);
1606
  set_objfile_data (unit->objfile, dwarf2_frame_objfile_data, fde);
1607
}
1608
 
1609
#ifdef CC_HAS_LONG_LONG
1610
#define DW64_CIE_ID 0xffffffffffffffffULL
1611
#else
1612
#define DW64_CIE_ID ~0
1613
#endif
1614
 
1615
static gdb_byte *decode_frame_entry (struct comp_unit *unit, gdb_byte *start,
1616
                                     int eh_frame_p);
1617
 
1618
/* Decode the next CIE or FDE.  Return NULL if invalid input, otherwise
1619
   the next byte to be processed.  */
1620
static gdb_byte *
1621
decode_frame_entry_1 (struct comp_unit *unit, gdb_byte *start, int eh_frame_p)
1622
{
1623
  gdb_byte *buf, *end;
1624
  LONGEST length;
1625
  unsigned int bytes_read;
1626
  int dwarf64_p;
1627
  ULONGEST cie_id;
1628
  ULONGEST cie_pointer;
1629
 
1630
  buf = start;
1631
  length = read_initial_length (unit->abfd, buf, &bytes_read);
1632
  buf += bytes_read;
1633
  end = buf + length;
1634
 
1635
  /* Are we still within the section? */
1636
  if (end > unit->dwarf_frame_buffer + unit->dwarf_frame_size)
1637
    return NULL;
1638
 
1639
  if (length == 0)
1640
    return end;
1641
 
1642
  /* Distinguish between 32 and 64-bit encoded frame info.  */
1643
  dwarf64_p = (bytes_read == 12);
1644
 
1645
  /* In a .eh_frame section, zero is used to distinguish CIEs from FDEs.  */
1646
  if (eh_frame_p)
1647
    cie_id = 0;
1648
  else if (dwarf64_p)
1649
    cie_id = DW64_CIE_ID;
1650
  else
1651
    cie_id = DW_CIE_ID;
1652
 
1653
  if (dwarf64_p)
1654
    {
1655
      cie_pointer = read_8_bytes (unit->abfd, buf);
1656
      buf += 8;
1657
    }
1658
  else
1659
    {
1660
      cie_pointer = read_4_bytes (unit->abfd, buf);
1661
      buf += 4;
1662
    }
1663
 
1664
  if (cie_pointer == cie_id)
1665
    {
1666
      /* This is a CIE.  */
1667
      struct dwarf2_cie *cie;
1668
      char *augmentation;
1669
      unsigned int cie_version;
1670
 
1671
      /* Record the offset into the .debug_frame section of this CIE.  */
1672
      cie_pointer = start - unit->dwarf_frame_buffer;
1673
 
1674
      /* Check whether we've already read it.  */
1675
      if (find_cie (unit, cie_pointer))
1676
        return end;
1677
 
1678
      cie = (struct dwarf2_cie *)
1679
        obstack_alloc (&unit->objfile->objfile_obstack,
1680
                       sizeof (struct dwarf2_cie));
1681
      cie->initial_instructions = NULL;
1682
      cie->cie_pointer = cie_pointer;
1683
 
1684
      /* The encoding for FDE's in a normal .debug_frame section
1685
         depends on the target address size.  */
1686
      cie->encoding = DW_EH_PE_absptr;
1687
 
1688
      /* We'll determine the final value later, but we need to
1689
         initialize it conservatively.  */
1690
      cie->signal_frame = 0;
1691
 
1692
      /* Check version number.  */
1693
      cie_version = read_1_byte (unit->abfd, buf);
1694
      if (cie_version != 1 && cie_version != 3)
1695
        return NULL;
1696
      cie->version = cie_version;
1697
      buf += 1;
1698
 
1699
      /* Interpret the interesting bits of the augmentation.  */
1700
      cie->augmentation = augmentation = (char *) buf;
1701
      buf += (strlen (augmentation) + 1);
1702
 
1703
      /* Ignore armcc augmentations.  We only use them for quirks,
1704
         and that doesn't happen until later.  */
1705
      if (strncmp (augmentation, "armcc", 5) == 0)
1706
        augmentation += strlen (augmentation);
1707
 
1708
      /* The GCC 2.x "eh" augmentation has a pointer immediately
1709
         following the augmentation string, so it must be handled
1710
         first.  */
1711
      if (augmentation[0] == 'e' && augmentation[1] == 'h')
1712
        {
1713
          /* Skip.  */
1714
          buf += TYPE_LENGTH (builtin_type_void_data_ptr);
1715
          augmentation += 2;
1716
        }
1717
 
1718
      cie->code_alignment_factor =
1719
        read_unsigned_leb128 (unit->abfd, buf, &bytes_read);
1720
      buf += bytes_read;
1721
 
1722
      cie->data_alignment_factor =
1723
        read_signed_leb128 (unit->abfd, buf, &bytes_read);
1724
      buf += bytes_read;
1725
 
1726
      if (cie_version == 1)
1727
        {
1728
          cie->return_address_register = read_1_byte (unit->abfd, buf);
1729
          bytes_read = 1;
1730
        }
1731
      else
1732
        cie->return_address_register = read_unsigned_leb128 (unit->abfd, buf,
1733
                                                             &bytes_read);
1734
      cie->return_address_register
1735
        = dwarf2_frame_adjust_regnum (current_gdbarch,
1736
                                      cie->return_address_register,
1737
                                      eh_frame_p);
1738
 
1739
      buf += bytes_read;
1740
 
1741
      cie->saw_z_augmentation = (*augmentation == 'z');
1742
      if (cie->saw_z_augmentation)
1743
        {
1744
          ULONGEST length;
1745
 
1746
          length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read);
1747
          buf += bytes_read;
1748
          if (buf > end)
1749
            return NULL;
1750
          cie->initial_instructions = buf + length;
1751
          augmentation++;
1752
        }
1753
 
1754
      while (*augmentation)
1755
        {
1756
          /* "L" indicates a byte showing how the LSDA pointer is encoded.  */
1757
          if (*augmentation == 'L')
1758
            {
1759
              /* Skip.  */
1760
              buf++;
1761
              augmentation++;
1762
            }
1763
 
1764
          /* "R" indicates a byte indicating how FDE addresses are encoded.  */
1765
          else if (*augmentation == 'R')
1766
            {
1767
              cie->encoding = *buf++;
1768
              augmentation++;
1769
            }
1770
 
1771
          /* "P" indicates a personality routine in the CIE augmentation.  */
1772
          else if (*augmentation == 'P')
1773
            {
1774
              /* Skip.  Avoid indirection since we throw away the result.  */
1775
              gdb_byte encoding = (*buf++) & ~DW_EH_PE_indirect;
1776
              read_encoded_value (unit, encoding, buf, &bytes_read);
1777
              buf += bytes_read;
1778
              augmentation++;
1779
            }
1780
 
1781
          /* "S" indicates a signal frame, such that the return
1782
             address must not be decremented to locate the call frame
1783
             info for the previous frame; it might even be the first
1784
             instruction of a function, so decrementing it would take
1785
             us to a different function.  */
1786
          else if (*augmentation == 'S')
1787
            {
1788
              cie->signal_frame = 1;
1789
              augmentation++;
1790
            }
1791
 
1792
          /* Otherwise we have an unknown augmentation.  Assume that either
1793
             there is no augmentation data, or we saw a 'z' prefix.  */
1794
          else
1795
            {
1796
              if (cie->initial_instructions)
1797
                buf = cie->initial_instructions;
1798
              break;
1799
            }
1800
        }
1801
 
1802
      cie->initial_instructions = buf;
1803
      cie->end = end;
1804
 
1805
      add_cie (unit, cie);
1806
    }
1807
  else
1808
    {
1809
      /* This is a FDE.  */
1810
      struct dwarf2_fde *fde;
1811
 
1812
      /* In an .eh_frame section, the CIE pointer is the delta between the
1813
         address within the FDE where the CIE pointer is stored and the
1814
         address of the CIE.  Convert it to an offset into the .eh_frame
1815
         section.  */
1816
      if (eh_frame_p)
1817
        {
1818
          cie_pointer = buf - unit->dwarf_frame_buffer - cie_pointer;
1819
          cie_pointer -= (dwarf64_p ? 8 : 4);
1820
        }
1821
 
1822
      /* In either case, validate the result is still within the section.  */
1823
      if (cie_pointer >= unit->dwarf_frame_size)
1824
        return NULL;
1825
 
1826
      fde = (struct dwarf2_fde *)
1827
        obstack_alloc (&unit->objfile->objfile_obstack,
1828
                       sizeof (struct dwarf2_fde));
1829
      fde->cie = find_cie (unit, cie_pointer);
1830
      if (fde->cie == NULL)
1831
        {
1832
          decode_frame_entry (unit, unit->dwarf_frame_buffer + cie_pointer,
1833
                              eh_frame_p);
1834
          fde->cie = find_cie (unit, cie_pointer);
1835
        }
1836
 
1837
      gdb_assert (fde->cie != NULL);
1838
 
1839
      fde->initial_location =
1840
        read_encoded_value (unit, fde->cie->encoding, buf, &bytes_read);
1841
      buf += bytes_read;
1842
 
1843
      fde->address_range =
1844
        read_encoded_value (unit, fde->cie->encoding & 0x0f, buf, &bytes_read);
1845
      buf += bytes_read;
1846
 
1847
      /* A 'z' augmentation in the CIE implies the presence of an
1848
         augmentation field in the FDE as well.  The only thing known
1849
         to be in here at present is the LSDA entry for EH.  So we
1850
         can skip the whole thing.  */
1851
      if (fde->cie->saw_z_augmentation)
1852
        {
1853
          ULONGEST length;
1854
 
1855
          length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read);
1856
          buf += bytes_read + length;
1857
          if (buf > end)
1858
            return NULL;
1859
        }
1860
 
1861
      fde->instructions = buf;
1862
      fde->end = end;
1863
 
1864
      fde->eh_frame_p = eh_frame_p;
1865
 
1866
      add_fde (unit, fde);
1867
    }
1868
 
1869
  return end;
1870
}
1871
 
1872
/* Read a CIE or FDE in BUF and decode it.  */
1873
static gdb_byte *
1874
decode_frame_entry (struct comp_unit *unit, gdb_byte *start, int eh_frame_p)
1875
{
1876
  enum { NONE, ALIGN4, ALIGN8, FAIL } workaround = NONE;
1877
  gdb_byte *ret;
1878
  const char *msg;
1879
  ptrdiff_t start_offset;
1880
 
1881
  while (1)
1882
    {
1883
      ret = decode_frame_entry_1 (unit, start, eh_frame_p);
1884
      if (ret != NULL)
1885
        break;
1886
 
1887
      /* We have corrupt input data of some form.  */
1888
 
1889
      /* ??? Try, weakly, to work around compiler/assembler/linker bugs
1890
         and mismatches wrt padding and alignment of debug sections.  */
1891
      /* Note that there is no requirement in the standard for any
1892
         alignment at all in the frame unwind sections.  Testing for
1893
         alignment before trying to interpret data would be incorrect.
1894
 
1895
         However, GCC traditionally arranged for frame sections to be
1896
         sized such that the FDE length and CIE fields happen to be
1897
         aligned (in theory, for performance).  This, unfortunately,
1898
         was done with .align directives, which had the side effect of
1899
         forcing the section to be aligned by the linker.
1900
 
1901
         This becomes a problem when you have some other producer that
1902
         creates frame sections that are not as strictly aligned.  That
1903
         produces a hole in the frame info that gets filled by the
1904
         linker with zeros.
1905
 
1906
         The GCC behaviour is arguably a bug, but it's effectively now
1907
         part of the ABI, so we're now stuck with it, at least at the
1908
         object file level.  A smart linker may decide, in the process
1909
         of compressing duplicate CIE information, that it can rewrite
1910
         the entire output section without this extra padding.  */
1911
 
1912
      start_offset = start - unit->dwarf_frame_buffer;
1913
      if (workaround < ALIGN4 && (start_offset & 3) != 0)
1914
        {
1915
          start += 4 - (start_offset & 3);
1916
          workaround = ALIGN4;
1917
          continue;
1918
        }
1919
      if (workaround < ALIGN8 && (start_offset & 7) != 0)
1920
        {
1921
          start += 8 - (start_offset & 7);
1922
          workaround = ALIGN8;
1923
          continue;
1924
        }
1925
 
1926
      /* Nothing left to try.  Arrange to return as if we've consumed
1927
         the entire input section.  Hopefully we'll get valid info from
1928
         the other of .debug_frame/.eh_frame.  */
1929
      workaround = FAIL;
1930
      ret = unit->dwarf_frame_buffer + unit->dwarf_frame_size;
1931
      break;
1932
    }
1933
 
1934
  switch (workaround)
1935
    {
1936
    case NONE:
1937
      break;
1938
 
1939
    case ALIGN4:
1940
      complaint (&symfile_complaints,
1941
                 _("Corrupt data in %s:%s; align 4 workaround apparently succeeded"),
1942
                 unit->dwarf_frame_section->owner->filename,
1943
                 unit->dwarf_frame_section->name);
1944
      break;
1945
 
1946
    case ALIGN8:
1947
      complaint (&symfile_complaints,
1948
                 _("Corrupt data in %s:%s; align 8 workaround apparently succeeded"),
1949
                 unit->dwarf_frame_section->owner->filename,
1950
                 unit->dwarf_frame_section->name);
1951
      break;
1952
 
1953
    default:
1954
      complaint (&symfile_complaints,
1955
                 _("Corrupt data in %s:%s"),
1956
                 unit->dwarf_frame_section->owner->filename,
1957
                 unit->dwarf_frame_section->name);
1958
      break;
1959
    }
1960
 
1961
  return ret;
1962
}
1963
 
1964
 
1965
/* FIXME: kettenis/20030504: This still needs to be integrated with
1966
   dwarf2read.c in a better way.  */
1967
 
1968
/* Imported from dwarf2read.c.  */
1969
extern asection *dwarf_frame_section;
1970
extern asection *dwarf_eh_frame_section;
1971
 
1972
/* Imported from dwarf2read.c.  */
1973
extern gdb_byte *dwarf2_read_section (struct objfile *objfile, asection *sectp);
1974
 
1975
void
1976
dwarf2_build_frame_info (struct objfile *objfile)
1977
{
1978
  struct comp_unit unit;
1979
  gdb_byte *frame_ptr;
1980
 
1981
  /* Build a minimal decoding of the DWARF2 compilation unit.  */
1982
  unit.abfd = objfile->obfd;
1983
  unit.objfile = objfile;
1984
  unit.dbase = 0;
1985
  unit.tbase = 0;
1986
 
1987
  /* First add the information from the .eh_frame section.  That way,
1988
     the FDEs from that section are searched last.  */
1989
  if (dwarf_eh_frame_section)
1990
    {
1991
      asection *got, *txt;
1992
 
1993
      unit.cie = NULL;
1994
      unit.dwarf_frame_buffer = dwarf2_read_section (objfile,
1995
                                                     dwarf_eh_frame_section);
1996
 
1997
      unit.dwarf_frame_size = bfd_get_section_size (dwarf_eh_frame_section);
1998
      unit.dwarf_frame_section = dwarf_eh_frame_section;
1999
 
2000
      /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base
2001
         that is used for the i386/amd64 target, which currently is
2002
         the only target in GCC that supports/uses the
2003
         DW_EH_PE_datarel encoding.  */
2004
      got = bfd_get_section_by_name (unit.abfd, ".got");
2005
      if (got)
2006
        unit.dbase = got->vma;
2007
 
2008
      /* GCC emits the DW_EH_PE_textrel encoding type on sh and ia64
2009
         so far.  */
2010
      txt = bfd_get_section_by_name (unit.abfd, ".text");
2011
      if (txt)
2012
        unit.tbase = txt->vma;
2013
 
2014
      frame_ptr = unit.dwarf_frame_buffer;
2015
      while (frame_ptr < unit.dwarf_frame_buffer + unit.dwarf_frame_size)
2016
        frame_ptr = decode_frame_entry (&unit, frame_ptr, 1);
2017
    }
2018
 
2019
  if (dwarf_frame_section)
2020
    {
2021
      unit.cie = NULL;
2022
      unit.dwarf_frame_buffer = dwarf2_read_section (objfile,
2023
                                                     dwarf_frame_section);
2024
      unit.dwarf_frame_size = bfd_get_section_size (dwarf_frame_section);
2025
      unit.dwarf_frame_section = dwarf_frame_section;
2026
 
2027
      frame_ptr = unit.dwarf_frame_buffer;
2028
      while (frame_ptr < unit.dwarf_frame_buffer + unit.dwarf_frame_size)
2029
        frame_ptr = decode_frame_entry (&unit, frame_ptr, 0);
2030
    }
2031
}
2032
 
2033
/* Provide a prototype to silence -Wmissing-prototypes.  */
2034
void _initialize_dwarf2_frame (void);
2035
 
2036
void
2037
_initialize_dwarf2_frame (void)
2038
{
2039
  dwarf2_frame_data = gdbarch_data_register_pre_init (dwarf2_frame_init);
2040
  dwarf2_frame_objfile_data = register_objfile_data ();
2041
}

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