/thirdparty/breakpad/common/dwarf/cfi_assembler.cc

  1// Copyright (c) 2010, Google Inc.
  2// All rights reserved.
  3//
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  5// modification, are permitted provided that the following conditions are
  6// met:
  7//
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  9// notice, this list of conditions and the following disclaimer.
 10//     * Redistributions in binary form must reproduce the above
 11// copyright notice, this list of conditions and the following disclaimer
 12// in the documentation and/or other materials provided with the
 13// distribution.
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 15// contributors may be used to endorse or promote products derived from
 16// this software without specific prior written permission.
 17//
 18// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 19// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 20// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 21// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 22// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 23// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 24// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 25// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 28// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 29
 30// Original author: Jim Blandy <jimb@mozilla.com> <jimb@red-bean.com>
 31
 32// cfi_assembler.cc: Implementation of google_breakpad::CFISection class.
 33// See cfi_assembler.h for details.
 34
 35#include "common/dwarf/cfi_assembler.h"
 36
 37#include <assert.h>
 38#include <stdlib.h>
 39
 40namespace google_breakpad {
 41
 42using dwarf2reader::DwarfPointerEncoding;
 43  
 44CFISection &CFISection::CIEHeader(u_int64_t code_alignment_factor,
 45                                  int data_alignment_factor,
 46                                  unsigned return_address_register,
 47                                  u_int8_t version,
 48                                  const string &augmentation,
 49                                  bool dwarf64) {
 50  assert(!entry_length_);
 51  entry_length_ = new PendingLength();
 52  in_fde_ = false;
 53
 54  if (dwarf64) {
 55    D32(kDwarf64InitialLengthMarker);
 56    D64(entry_length_->length);
 57    entry_length_->start = Here();
 58    D64(eh_frame_ ? kEHFrame64CIEIdentifier : kDwarf64CIEIdentifier);
 59  } else {
 60    D32(entry_length_->length);
 61    entry_length_->start = Here();
 62    D32(eh_frame_ ? kEHFrame32CIEIdentifier : kDwarf32CIEIdentifier);
 63  }
 64  D8(version);
 65  AppendCString(augmentation);
 66  ULEB128(code_alignment_factor);
 67  LEB128(data_alignment_factor);
 68  if (version == 1)
 69    D8(return_address_register);
 70  else
 71    ULEB128(return_address_register);
 72  return *this;
 73}
 74
 75CFISection &CFISection::FDEHeader(Label cie_pointer,
 76                                  u_int64_t initial_location,
 77                                  u_int64_t address_range,
 78                                  bool dwarf64) {
 79  assert(!entry_length_);
 80  entry_length_ = new PendingLength();
 81  in_fde_ = true;
 82  fde_start_address_ = initial_location;
 83
 84  if (dwarf64) {
 85    D32(0xffffffff);
 86    D64(entry_length_->length);
 87    entry_length_->start = Here();
 88    if (eh_frame_)
 89      D64(Here() - cie_pointer);
 90    else
 91      D64(cie_pointer);
 92  } else {
 93    D32(entry_length_->length);
 94    entry_length_->start = Here();
 95    if (eh_frame_)
 96      D32(Here() - cie_pointer);
 97    else
 98      D32(cie_pointer);
 99  }
100  EncodedPointer(initial_location);
101  // The FDE length in an .eh_frame section uses the same encoding as the
102  // initial location, but ignores the base address (selected by the upper
103  // nybble of the encoding), as it's a length, not an address that can be
104  // made relative.
105  EncodedPointer(address_range,
106                 DwarfPointerEncoding(pointer_encoding_ & 0x0f));
107  return *this;
108}
109
110CFISection &CFISection::FinishEntry() {
111  assert(entry_length_);
112  Align(address_size_, dwarf2reader::DW_CFA_nop);
113  entry_length_->length = Here() - entry_length_->start;
114  delete entry_length_;
115  entry_length_ = NULL;
116  in_fde_ = false;
117  return *this;
118}
119
120CFISection &CFISection::EncodedPointer(u_int64_t address,
121                                       DwarfPointerEncoding encoding,
122                                       const EncodedPointerBases &bases) {
123  // Omitted data is extremely easy to emit.
124  if (encoding == dwarf2reader::DW_EH_PE_omit)
125    return *this;
126
127  // If (encoding & dwarf2reader::DW_EH_PE_indirect) != 0, then we assume
128  // that ADDRESS is the address at which the pointer is stored --- in
129  // other words, that bit has no effect on how we write the pointer.
130  encoding = DwarfPointerEncoding(encoding & ~dwarf2reader::DW_EH_PE_indirect);
131
132  // Find the base address to which this pointer is relative. The upper
133  // nybble of the encoding specifies this.
134  u_int64_t base;
135  switch (encoding & 0xf0) {
136    case dwarf2reader::DW_EH_PE_absptr:  base = 0;                  break;
137    case dwarf2reader::DW_EH_PE_pcrel:   base = bases.cfi + Size(); break;
138    case dwarf2reader::DW_EH_PE_textrel: base = bases.text;         break;
139    case dwarf2reader::DW_EH_PE_datarel: base = bases.data;         break;
140    case dwarf2reader::DW_EH_PE_funcrel: base = fde_start_address_; break;
141    case dwarf2reader::DW_EH_PE_aligned: base = 0;                  break;
142    default: abort();
143  };
144
145  // Make ADDRESS relative. Yes, this is appropriate even for "absptr"
146  // values; see gcc/unwind-pe.h.
147  address -= base;
148
149  // Align the pointer, if required.
150  if ((encoding & 0xf0) == dwarf2reader::DW_EH_PE_aligned)
151    Align(AddressSize());
152
153  // Append ADDRESS to this section in the appropriate form. For the
154  // fixed-width forms, we don't need to differentiate between signed and
155  // unsigned encodings, because ADDRESS has already been extended to 64
156  // bits before it was passed to us.
157  switch (encoding & 0x0f) {
158    case dwarf2reader::DW_EH_PE_absptr:
159      Address(address);
160      break;
161
162    case dwarf2reader::DW_EH_PE_uleb128:
163      ULEB128(address);
164      break;
165
166    case dwarf2reader::DW_EH_PE_sleb128:
167      LEB128(address);
168      break;
169
170    case dwarf2reader::DW_EH_PE_udata2:
171    case dwarf2reader::DW_EH_PE_sdata2:
172      D16(address);
173      break;
174
175    case dwarf2reader::DW_EH_PE_udata4:
176    case dwarf2reader::DW_EH_PE_sdata4:
177      D32(address);
178      break;
179
180    case dwarf2reader::DW_EH_PE_udata8:
181    case dwarf2reader::DW_EH_PE_sdata8:
182      D64(address);
183      break;
184
185    default:
186      abort();
187  }
188
189  return *this;
190};
191
192const u_int32_t CFISection::kDwarf64InitialLengthMarker;
193const u_int32_t CFISection::kDwarf32CIEIdentifier;
194const u_int64_t CFISection::kDwarf64CIEIdentifier;
195const u_int32_t CFISection::kEHFrame32CIEIdentifier;
196const u_int64_t CFISection::kEHFrame64CIEIdentifier;
197
198} // namespace google_breakpad