1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ART_COMPILER_DEBUG_DWARF_HEADERS_H_
18#define ART_COMPILER_DEBUG_DWARF_HEADERS_H_
19
20#include <cstdint>
21
22#include "base/array_ref.h"
23#include "debug/dwarf/debug_frame_opcode_writer.h"
24#include "debug/dwarf/debug_info_entry_writer.h"
25#include "debug/dwarf/debug_line_opcode_writer.h"
26#include "debug/dwarf/dwarf_constants.h"
27#include "debug/dwarf/register.h"
28#include "debug/dwarf/writer.h"
29
30namespace art {
31namespace dwarf {
32
33// Note that all headers start with 32-bit length.
34// DWARF also supports 64-bit lengths, but we never use that.
35// It is intended to support very large debug sections (>4GB),
36// and compilers are expected *not* to use it by default.
37// In particular, it is not related to machine architecture.
38
39// Write common information entry (CIE) to .debug_frame or .eh_frame section.
40template<typename Vector>
41void WriteCIE(bool is64bit,
42              Reg return_address_register,
43              const DebugFrameOpCodeWriter<Vector>& opcodes,
44              CFIFormat format,
45              std::vector<uint8_t>* buffer) {
46  static_assert(std::is_same<typename Vector::value_type, uint8_t>::value, "Invalid value type");
47
48  Writer<> writer(buffer);
49  size_t cie_header_start_ = writer.data()->size();
50  writer.PushUint32(0);  // Length placeholder.
51  writer.PushUint32((format == DW_EH_FRAME_FORMAT) ? 0 : 0xFFFFFFFF);  // CIE id.
52  writer.PushUint8(1);   // Version.
53  writer.PushString("zR");
54  writer.PushUleb128(DebugFrameOpCodeWriter<Vector>::kCodeAlignmentFactor);
55  writer.PushSleb128(DebugFrameOpCodeWriter<Vector>::kDataAlignmentFactor);
56  writer.PushUleb128(return_address_register.num());  // ubyte in DWARF2.
57  writer.PushUleb128(1);  // z: Augmentation data size.
58  if (is64bit) {
59    if (format == DW_EH_FRAME_FORMAT) {
60      writer.PushUint8(DW_EH_PE_pcrel | DW_EH_PE_sdata8);   // R: Pointer encoding.
61    } else {
62      DCHECK(format == DW_DEBUG_FRAME_FORMAT);
63      writer.PushUint8(DW_EH_PE_absptr | DW_EH_PE_udata8);  // R: Pointer encoding.
64    }
65  } else {
66    if (format == DW_EH_FRAME_FORMAT) {
67      writer.PushUint8(DW_EH_PE_pcrel | DW_EH_PE_sdata4);   // R: Pointer encoding.
68    } else {
69      DCHECK(format == DW_DEBUG_FRAME_FORMAT);
70      writer.PushUint8(DW_EH_PE_absptr | DW_EH_PE_udata4);  // R: Pointer encoding.
71    }
72  }
73  writer.PushData(opcodes.data());
74  writer.Pad(is64bit ? 8 : 4);
75  writer.UpdateUint32(cie_header_start_, writer.data()->size() - cie_header_start_ - 4);
76}
77
78// Write frame description entry (FDE) to .debug_frame or .eh_frame section.
79inline
80void WriteFDE(bool is64bit,
81              uint64_t section_address,  // Absolute address of the section.
82              uint64_t cie_address,  // Absolute address of last CIE.
83              uint64_t code_address,
84              uint64_t code_size,
85              const ArrayRef<const uint8_t>& opcodes,
86              CFIFormat format,
87              uint64_t buffer_address,  // Address of buffer in linked application.
88              std::vector<uint8_t>* buffer,
89              std::vector<uintptr_t>* patch_locations) {
90  CHECK_GE(cie_address, section_address);
91  CHECK_GE(buffer_address, section_address);
92
93  Writer<> writer(buffer);
94  size_t fde_header_start = writer.data()->size();
95  writer.PushUint32(0);  // Length placeholder.
96  if (format == DW_EH_FRAME_FORMAT) {
97    uint32_t cie_pointer = (buffer_address + buffer->size()) - cie_address;
98    writer.PushUint32(cie_pointer);
99  } else {
100    DCHECK(format == DW_DEBUG_FRAME_FORMAT);
101    uint32_t cie_pointer = cie_address - section_address;
102    writer.PushUint32(cie_pointer);
103  }
104  if (format == DW_EH_FRAME_FORMAT) {
105    // .eh_frame encodes the location as relative address.
106    code_address -= buffer_address + buffer->size();
107  } else {
108    DCHECK(format == DW_DEBUG_FRAME_FORMAT);
109    // Relocate code_address if it has absolute value.
110    patch_locations->push_back(buffer_address + buffer->size() - section_address);
111  }
112  if (is64bit) {
113    writer.PushUint64(code_address);
114    writer.PushUint64(code_size);
115  } else {
116    writer.PushUint32(code_address);
117    writer.PushUint32(code_size);
118  }
119  writer.PushUleb128(0);  // Augmentation data size.
120  writer.PushData(opcodes.data(), opcodes.size());
121  writer.Pad(is64bit ? 8 : 4);
122  writer.UpdateUint32(fde_header_start, writer.data()->size() - fde_header_start - 4);
123}
124
125// Write compilation unit (CU) to .debug_info section.
126template<typename Vector>
127void WriteDebugInfoCU(uint32_t debug_abbrev_offset,
128                      const DebugInfoEntryWriter<Vector>& entries,
129                      size_t debug_info_offset,  // offset from start of .debug_info.
130                      std::vector<uint8_t>* debug_info,
131                      std::vector<uintptr_t>* debug_info_patches) {
132  static_assert(std::is_same<typename Vector::value_type, uint8_t>::value, "Invalid value type");
133
134  Writer<> writer(debug_info);
135  size_t start = writer.data()->size();
136  writer.PushUint32(0);  // Length placeholder.
137  writer.PushUint16(4);  // Version.
138  writer.PushUint32(debug_abbrev_offset);
139  writer.PushUint8(entries.Is64bit() ? 8 : 4);
140  size_t entries_offset = writer.data()->size();
141  DCHECK_EQ(entries_offset, DebugInfoEntryWriter<Vector>::kCompilationUnitHeaderSize);
142  writer.PushData(entries.data());
143  writer.UpdateUint32(start, writer.data()->size() - start - 4);
144  // Copy patch locations and make them relative to .debug_info section.
145  for (uintptr_t patch_location : entries.GetPatchLocations()) {
146    debug_info_patches->push_back(debug_info_offset + entries_offset + patch_location);
147  }
148}
149
150struct FileEntry {
151  std::string file_name;
152  int directory_index;
153  int modification_time;
154  int file_size;
155};
156
157// Write line table to .debug_line section.
158template<typename Vector>
159void WriteDebugLineTable(const std::vector<std::string>& include_directories,
160                         const std::vector<FileEntry>& files,
161                         const DebugLineOpCodeWriter<Vector>& opcodes,
162                         size_t debug_line_offset,  // offset from start of .debug_line.
163                         std::vector<uint8_t>* debug_line,
164                         std::vector<uintptr_t>* debug_line_patches) {
165  static_assert(std::is_same<typename Vector::value_type, uint8_t>::value, "Invalid value type");
166
167  Writer<> writer(debug_line);
168  size_t header_start = writer.data()->size();
169  writer.PushUint32(0);  // Section-length placeholder.
170  writer.PushUint16(3);  // .debug_line version.
171  size_t header_length_pos = writer.data()->size();
172  writer.PushUint32(0);  // Header-length placeholder.
173  writer.PushUint8(1 << opcodes.GetCodeFactorBits());
174  writer.PushUint8(DebugLineOpCodeWriter<Vector>::kDefaultIsStmt ? 1 : 0);
175  writer.PushInt8(DebugLineOpCodeWriter<Vector>::kLineBase);
176  writer.PushUint8(DebugLineOpCodeWriter<Vector>::kLineRange);
177  writer.PushUint8(DebugLineOpCodeWriter<Vector>::kOpcodeBase);
178  static const int opcode_lengths[DebugLineOpCodeWriter<Vector>::kOpcodeBase] = {
179      0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1 };
180  for (int i = 1; i < DebugLineOpCodeWriter<Vector>::kOpcodeBase; i++) {
181    writer.PushUint8(opcode_lengths[i]);
182  }
183  for (const std::string& directory : include_directories) {
184    writer.PushData(directory.data(), directory.size() + 1);
185  }
186  writer.PushUint8(0);  // Terminate include_directories list.
187  for (const FileEntry& file : files) {
188    writer.PushData(file.file_name.data(), file.file_name.size() + 1);
189    writer.PushUleb128(file.directory_index);
190    writer.PushUleb128(file.modification_time);
191    writer.PushUleb128(file.file_size);
192  }
193  writer.PushUint8(0);  // Terminate file list.
194  writer.UpdateUint32(header_length_pos, writer.data()->size() - header_length_pos - 4);
195  size_t opcodes_offset = writer.data()->size();
196  writer.PushData(opcodes.data());
197  writer.UpdateUint32(header_start, writer.data()->size() - header_start - 4);
198  // Copy patch locations and make them relative to .debug_line section.
199  for (uintptr_t patch_location : opcodes.GetPatchLocations()) {
200    debug_line_patches->push_back(debug_line_offset + opcodes_offset + patch_location);
201  }
202}
203
204}  // namespace dwarf
205}  // namespace art
206
207#endif  // ART_COMPILER_DEBUG_DWARF_HEADERS_H_
208