File: reduced_debug_output.cc

package info (click to toggle)
binutils 2.28-5
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 271,848 kB
  • sloc: ansic: 1,419,727; asm: 623,424; cpp: 125,042; exp: 64,226; makefile: 56,536; sh: 21,234; lisp: 15,206; yacc: 14,889; perl: 2,111; ada: 1,681; lex: 1,645; pascal: 1,438; cs: 879; sed: 195; python: 154; xml: 95; awk: 25
file content (376 lines) | stat: -rw-r--r-- 14,304 bytes parent folder | download
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
// reduced_debug_output.cc -- output reduced debugging information to save space

// Copyright (C) 2008-2017 Free Software Foundation, Inc.
// Written by Caleb Howe <cshowe@google.com>.

// This file is part of gold.

// 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, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.

#include "gold.h"

#include "parameters.h"
#include "options.h"
#include "dwarf.h"
#include "dwarf_reader.h"
#include "reduced_debug_output.h"
#include "int_encoding.h"

#include <vector>

namespace gold
{

// Given a pointer to the beginning of a die and the beginning of the associated
// abbreviation fills in die_end with the end of the information entry.  If
// successful returns true.  Get_die_end also takes a pointer to the end of the
// buffer containing the die.  If die_end would be beyond the end of the
// buffer, or if an unsupported dwarf form is encountered returns false.
bool
Output_reduced_debug_info_section::get_die_end(
    unsigned char* die, unsigned char* abbrev, unsigned char** die_end,
    unsigned char* buffer_end, int address_size, bool is64)
{
  size_t LEB_size;
  uint64_t LEB_decoded;
  for(;;)
    {
      uint64_t attribute = read_unsigned_LEB_128(abbrev, &LEB_size);
      abbrev += LEB_size;
      elfcpp::DW_FORM form =
          static_cast<elfcpp::DW_FORM>(read_unsigned_LEB_128(abbrev,
                                                             &LEB_size));
      abbrev += LEB_size;
      if (!(attribute || form))
        break;
      if (die >= buffer_end)
        return false;
      switch(form)
        {
          case elfcpp::DW_FORM_flag_present:
            break;
          case elfcpp::DW_FORM_strp:
          case elfcpp::DW_FORM_sec_offset:
            die += is64 ? 8 : 4;
            break;
          case elfcpp::DW_FORM_addr:
          case elfcpp::DW_FORM_ref_addr:
            die += address_size;
            break;
          case elfcpp::DW_FORM_block1:
            die += *die;
            die += 1;
            break;
          case elfcpp::DW_FORM_block2:
            {
              uint16_t block_size;
              block_size = read_from_pointer<16>(&die);
              die += block_size;
              break;
            }
          case elfcpp::DW_FORM_block4:
            {
              uint32_t block_size;
              block_size = read_from_pointer<32>(&die);
              die += block_size;
              break;
            }
          case elfcpp::DW_FORM_block:
          case elfcpp::DW_FORM_exprloc:
            LEB_decoded = read_unsigned_LEB_128(die, &LEB_size);
            die += (LEB_decoded + LEB_size);
            break;
          case elfcpp::DW_FORM_data1:
          case elfcpp::DW_FORM_ref1:
          case elfcpp::DW_FORM_flag:
            die += 1;
            break;
          case elfcpp::DW_FORM_data2:
          case elfcpp::DW_FORM_ref2:
            die += 2;
            break;
          case elfcpp::DW_FORM_data4:
          case elfcpp::DW_FORM_ref4:
            die += 4;
            break;
          case elfcpp::DW_FORM_data8:
          case elfcpp::DW_FORM_ref8:
          case elfcpp::DW_FORM_ref_sig8:
            die += 8;
            break;
          case elfcpp::DW_FORM_ref_udata:
          case elfcpp::DW_FORM_udata:
            read_unsigned_LEB_128(die, &LEB_size);
            die += LEB_size;
            break;
          case elfcpp::DW_FORM_sdata:
            read_signed_LEB_128(die, &LEB_size);
            die += LEB_size;
            break;
          case elfcpp::DW_FORM_string:
            {
              size_t length = strlen(reinterpret_cast<char*>(die));
              die += length + 1;
              break;
            }
          case elfcpp::DW_FORM_indirect:
          case elfcpp::DW_FORM_GNU_addr_index:
          case elfcpp::DW_FORM_GNU_str_index:
          default:
            return false;
      }
    }
  *die_end = die;
  return true;
}

void
Output_reduced_debug_abbrev_section::set_final_data_size()
{
  if (this->sized_ || this->failed_)
    return;

  uint64_t abbrev_number;
  size_t LEB_size;
  unsigned char* abbrev_data = this->postprocessing_buffer();
  unsigned char* abbrev_end = this->postprocessing_buffer() +
                              this->postprocessing_buffer_size();
  this->write_to_postprocessing_buffer();
  while(abbrev_data < abbrev_end)
    {
      uint64_t abbrev_offset = abbrev_data - this->postprocessing_buffer();
      while((abbrev_number = read_unsigned_LEB_128(abbrev_data, &LEB_size)))
        {
          if (abbrev_data >= abbrev_end)
            {
              failed("Debug abbreviations extend beyond .debug_abbrev "
                     "section; failed to reduce debug abbreviations");
              return;
            }
          abbrev_data += LEB_size;

          // Together with the abbreviation number these fields make up
          // the header for each abbreviation.
          uint64_t abbrev_type = read_unsigned_LEB_128(abbrev_data, &LEB_size);
          abbrev_data += LEB_size;

          // This would ordinarily be the has_children field of the
          // abbreviation.  But it's going to be false after reducing the
          // information, so there's no point in storing it.
          abbrev_data++;

          // Read to the end of the current abbreviation.
          // This is indicated by two zero unsigned LEBs in a row.  We don't
          // need to parse the data yet, so we just scan through the data
          // looking for two consecutive 0 bytes indicating the end of the
          // abbreviation.
          unsigned char* current_abbrev;
          for (current_abbrev = abbrev_data;
               current_abbrev[0] || current_abbrev[1];
               current_abbrev++)
            {
              if (current_abbrev >= abbrev_end)
                {
                  this->failed(_("Debug abbreviations extend beyond "
				 ".debug_abbrev section; failed to reduce "
				 "debug abbreviations"));
                  return;
                }
            }
          // Account for the two nulls and advance to the start of the
          // next abbreviation.
          current_abbrev += 2;

          // We're eliminating every entry except for compile units, so we
          // only need to store abbreviations that describe them
          if (abbrev_type == elfcpp::DW_TAG_compile_unit)
            {
              write_unsigned_LEB_128(&this->data_, ++this->abbrev_count_);
              write_unsigned_LEB_128(&this->data_, abbrev_type);
              // has_children is false for all entries
              this->data_.push_back(0);
              this->abbrev_mapping_[std::make_pair(abbrev_offset,
                                                   abbrev_number)] =
                  std::make_pair(abbrev_count_, this->data_.size());
              this->data_.insert(this->data_.end(), abbrev_data,
                                 current_abbrev);
            }
          abbrev_data = current_abbrev;
        }
      gold_assert(LEB_size == 1);
      abbrev_data += LEB_size;
    }
  // Null terminate the list of abbreviations
  this->data_.push_back(0);
  this->set_data_size(data_.size());
  this->sized_ = true;
}

void
Output_reduced_debug_abbrev_section::do_write(Output_file* of)
{
  off_t offset = this->offset();
  off_t data_size = this->data_size();
  unsigned char* view = of->get_output_view(offset, data_size);
  if (this->failed_)
    memcpy(view, this->postprocessing_buffer(),
           this->postprocessing_buffer_size());
  else
    memcpy(view, &this->data_.front(), data_size);
  of->write_output_view(offset, data_size, view);
}

// Locates the abbreviation with abbreviation_number abbrev_number in the
// abbreviation table at offset abbrev_offset.  abbrev_number is updated with
// its new abbreviation number and a pointer to the beginning of the
// abbreviation is returned.
unsigned char*
Output_reduced_debug_abbrev_section::get_new_abbrev(
  uint64_t* abbrev_number, uint64_t abbrev_offset)
{
  set_final_data_size();
  std::pair<uint64_t, uint64_t> abbrev_info =
      this->abbrev_mapping_[std::make_pair(abbrev_offset, *abbrev_number)];
  *abbrev_number = abbrev_info.first;
  return &this->data_[abbrev_info.second];
}

void Output_reduced_debug_info_section::set_final_data_size()
{
  if (this->failed_)
    return;
  unsigned char* debug_info = this->postprocessing_buffer();
  unsigned char* debug_info_end = (this->postprocessing_buffer()
				   + this->postprocessing_buffer_size());
  unsigned char* next_compile_unit;
  this->write_to_postprocessing_buffer();

  while (debug_info < debug_info_end)
    {
      uint32_t compile_unit_start = read_from_pointer<32>(&debug_info);
      // The first 4 bytes of each compile unit determine whether or
      // not we're using dwarf32 or dwarf64.  This is not necessarily
      // related to whether the binary is 32 or 64 bits.
      if (compile_unit_start == 0xFFFFFFFF)
        {
          // Technically the size can be up to 96 bits.  Rather than handle
          // 96/128 bit integers we just truncate the size at 64 bits.
          if (0 != read_from_pointer<32>(&debug_info))
            {
              this->failed(_("Extremely large compile unit in debug info; "
			     "failed to reduce debug info"));
              return;
            }
          const int dwarf64_header_size = sizeof(uint64_t) + sizeof(uint16_t) +
                                          sizeof(uint64_t) + sizeof(uint8_t);
          if (debug_info + dwarf64_header_size >= debug_info_end)
            {
              this->failed(_("Debug info extends beyond .debug_info section;"
			     "failed to reduce debug info"));
              return;
            }

          uint64_t compile_unit_size = read_from_pointer<64>(&debug_info);
          next_compile_unit = debug_info + compile_unit_size;
          uint16_t version = read_from_pointer<16>(&debug_info);
          uint64_t abbrev_offset = read_from_pointer<64>(&debug_info);
          uint8_t address_size = read_from_pointer<8>(&debug_info);
          size_t LEB_size;
          uint64_t abbreviation_number = read_unsigned_LEB_128(debug_info,
                                                               &LEB_size);
          debug_info += LEB_size;
          unsigned char* die_abbrev = this->associated_abbrev_->get_new_abbrev(
              &abbreviation_number, abbrev_offset);
          unsigned char* die_end;
          if (!this->get_die_end(debug_info, die_abbrev, &die_end,
                                 debug_info_end, address_size, true))
            {
              this->failed(_("Invalid DIE in debug info; "
			     "failed to reduce debug info"));
              return;
            }

          insert_into_vector<32>(&this->data_, 0xFFFFFFFF);
          insert_into_vector<32>(&this->data_, 0);
          insert_into_vector<64>(
              &this->data_,
              (11 + get_length_as_unsigned_LEB_128(abbreviation_number)
	       + die_end - debug_info));
          insert_into_vector<16>(&this->data_, version);
          insert_into_vector<64>(&this->data_, 0);
          insert_into_vector<8>(&this->data_, address_size);
          write_unsigned_LEB_128(&this->data_, abbreviation_number);
          this->data_.insert(this->data_.end(), debug_info, die_end);
        }
      else
        {
          const int dwarf32_header_size =
              sizeof(uint16_t) + sizeof(uint32_t) + sizeof(uint8_t);
          if (debug_info + dwarf32_header_size >= debug_info_end)
            {
              this->failed(_("Debug info extends beyond .debug_info section; "
			     "failed to reduce debug info"));
              return;
            }
          uint32_t compile_unit_size = compile_unit_start;
          next_compile_unit = debug_info + compile_unit_size;
          uint16_t version = read_from_pointer<16>(&debug_info);
          uint32_t abbrev_offset = read_from_pointer<32>(&debug_info);
          uint8_t address_size = read_from_pointer<8>(&debug_info);
          size_t LEB_size;
          uint64_t abbreviation_number = read_unsigned_LEB_128(debug_info,
                                                               &LEB_size);
          debug_info += LEB_size;
          unsigned char* die_abbrev = this->associated_abbrev_->get_new_abbrev(
              &abbreviation_number, abbrev_offset);
          unsigned char* die_end;
          if (!this->get_die_end(debug_info, die_abbrev, &die_end,
                                 debug_info_end, address_size, false))
            {
              this->failed(_("Invalid DIE in debug info; "
			     "failed to reduce debug info"));
              return;
            }

          insert_into_vector<32>(
              &this->data_,
              (7 + get_length_as_unsigned_LEB_128(abbreviation_number)
	       + die_end - debug_info));
          insert_into_vector<16>(&this->data_, version);
          insert_into_vector<32>(&this->data_, 0);
          insert_into_vector<8>(&this->data_, address_size);
          write_unsigned_LEB_128(&this->data_, abbreviation_number);
          this->data_.insert(this->data_.end(), debug_info, die_end);
        }
      debug_info = next_compile_unit;
    }
  this->set_data_size(data_.size());
}

void Output_reduced_debug_info_section::do_write(Output_file* of)
{
  off_t offset = this->offset();
  off_t data_size = this->data_size();
  unsigned char* view = of->get_output_view(offset, data_size);
  if (this->failed_)
    memcpy(view, this->postprocessing_buffer(),
           this->postprocessing_buffer_size());
  else
    memcpy(view, &this->data_.front(), data_size);
  of->write_output_view(offset, data_size, view);
}

} // End namespace gold.