1 /*
2 * Copyright (C) 2016 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 #include "elf_debug_writer.h"
18
19 #include <type_traits>
20 #include <unordered_map>
21 #include <vector>
22
23 #include "base/array_ref.h"
24 #include "base/stl_util.h"
25 #include "debug/elf_compilation_unit.h"
26 #include "debug/elf_debug_frame_writer.h"
27 #include "debug/elf_debug_info_writer.h"
28 #include "debug/elf_debug_line_writer.h"
29 #include "debug/elf_debug_loc_writer.h"
30 #include "debug/elf_symtab_writer.h"
31 #include "debug/method_debug_info.h"
32 #include "dwarf/dwarf_constants.h"
33 #include "elf/elf_builder.h"
34 #include "elf/elf_debug_reader.h"
35 #include "elf/elf_utils.h"
36 #include "elf/xz_utils.h"
37 #include "jit/debugger_interface.h"
38 #include "oat/oat.h"
39 #include "stream/vector_output_stream.h"
40
41 namespace art HIDDEN {
42 namespace debug {
43
44 using ElfRuntimeTypes = std::conditional<sizeof(void*) == 4, ElfTypes32, ElfTypes64>::type;
45
46 template <typename ElfTypes>
WriteDebugInfo(ElfBuilder<ElfTypes> * builder,const DebugInfo & debug_info)47 void WriteDebugInfo(ElfBuilder<ElfTypes>* builder,
48 const DebugInfo& debug_info) {
49 // Write .strtab and .symtab.
50 WriteDebugSymbols(builder, /* mini-debug-info= */ false, debug_info);
51
52 // Write .debug_frame.
53 WriteCFISection(builder, debug_info.compiled_methods);
54
55 // Group the methods into compilation units based on class.
56 std::unordered_map<const dex::ClassDef*, ElfCompilationUnit> class_to_compilation_unit;
57 for (const MethodDebugInfo& mi : debug_info.compiled_methods) {
58 if (mi.dex_file != nullptr) {
59 auto& dex_class_def = mi.dex_file->GetClassDef(mi.class_def_index);
60 ElfCompilationUnit& cu = class_to_compilation_unit[&dex_class_def];
61 cu.methods.push_back(&mi);
62 // All methods must have the same addressing mode otherwise the min/max below does not work.
63 DCHECK_EQ(cu.methods.front()->is_code_address_text_relative, mi.is_code_address_text_relative);
64 cu.is_code_address_text_relative = mi.is_code_address_text_relative;
65 cu.code_address = std::min(cu.code_address, mi.code_address);
66 cu.code_end = std::max(cu.code_end, mi.code_address + mi.code_size);
67 }
68 }
69
70 // Sort compilation units to make the compiler output deterministic.
71 std::vector<ElfCompilationUnit> compilation_units;
72 compilation_units.reserve(class_to_compilation_unit.size());
73 for (auto& it : class_to_compilation_unit) {
74 // The .debug_line section requires the methods to be sorted by code address.
75 std::stable_sort(it.second.methods.begin(),
76 it.second.methods.end(),
77 [](const MethodDebugInfo* a, const MethodDebugInfo* b) {
78 return a->code_address < b->code_address;
79 });
80 compilation_units.push_back(std::move(it.second));
81 }
82 std::sort(compilation_units.begin(),
83 compilation_units.end(),
84 [](ElfCompilationUnit& a, ElfCompilationUnit& b) {
85 // Sort by index of the first method within the method_infos array.
86 // This assumes that the order of method_infos is deterministic.
87 // Code address is not good for sorting due to possible duplicates.
88 return a.methods.front() < b.methods.front();
89 });
90
91 // Write .debug_line section.
92 if (!compilation_units.empty()) {
93 ElfDebugLineWriter<ElfTypes> line_writer(builder);
94 line_writer.Start();
95 for (auto& compilation_unit : compilation_units) {
96 line_writer.WriteCompilationUnit(compilation_unit);
97 }
98 line_writer.End();
99 }
100
101 // Write .debug_info section.
102 if (!compilation_units.empty()) {
103 ElfDebugInfoWriter<ElfTypes> info_writer(builder);
104 info_writer.Start();
105 for (const auto& compilation_unit : compilation_units) {
106 ElfCompilationUnitWriter<ElfTypes> cu_writer(&info_writer);
107 cu_writer.Write(compilation_unit);
108 }
109 info_writer.End();
110 }
111 }
112
113 template <typename ElfTypes>
MakeMiniDebugInfoInternal(InstructionSet isa,const InstructionSetFeatures * features,typename ElfTypes::Addr text_section_address,size_t text_section_size,typename ElfTypes::Addr dex_section_address,size_t dex_section_size,const DebugInfo & debug_info)114 static std::vector<uint8_t> MakeMiniDebugInfoInternal(
115 InstructionSet isa,
116 [[maybe_unused]] const InstructionSetFeatures* features,
117 typename ElfTypes::Addr text_section_address,
118 size_t text_section_size,
119 typename ElfTypes::Addr dex_section_address,
120 size_t dex_section_size,
121 const DebugInfo& debug_info) {
122 std::vector<uint8_t> buffer;
123 buffer.reserve(KB);
124 VectorOutputStream out("Mini-debug-info ELF file", &buffer);
125 std::unique_ptr<ElfBuilder<ElfTypes>> builder(new ElfBuilder<ElfTypes>(isa, &out));
126 builder->Start(/* write_program_headers= */ false);
127 // Mirror ELF sections as NOBITS since the added symbols will reference them.
128 if (text_section_size != 0) {
129 builder->GetText()->AllocateVirtualMemory(text_section_address, text_section_size);
130 }
131 if (dex_section_size != 0) {
132 builder->GetDex()->AllocateVirtualMemory(dex_section_address, dex_section_size);
133 }
134 if (!debug_info.Empty()) {
135 WriteDebugSymbols(builder.get(), /* mini-debug-info= */ true, debug_info);
136 }
137 if (!debug_info.compiled_methods.empty()) {
138 WriteCFISection(builder.get(), debug_info.compiled_methods);
139 }
140 builder->End();
141 CHECK(builder->Good());
142 std::vector<uint8_t> compressed_buffer;
143 compressed_buffer.reserve(buffer.size() / 4);
144 XzCompress(ArrayRef<const uint8_t>(buffer), &compressed_buffer);
145 return compressed_buffer;
146 }
147
MakeMiniDebugInfo(InstructionSet isa,const InstructionSetFeatures * features,uint64_t text_section_address,size_t text_section_size,uint64_t dex_section_address,size_t dex_section_size,const DebugInfo & debug_info)148 std::vector<uint8_t> MakeMiniDebugInfo(
149 InstructionSet isa,
150 const InstructionSetFeatures* features,
151 uint64_t text_section_address,
152 size_t text_section_size,
153 uint64_t dex_section_address,
154 size_t dex_section_size,
155 const DebugInfo& debug_info) {
156 if (Is64BitInstructionSet(isa)) {
157 return MakeMiniDebugInfoInternal<ElfTypes64>(isa,
158 features,
159 text_section_address,
160 text_section_size,
161 dex_section_address,
162 dex_section_size,
163 debug_info);
164 } else {
165 return MakeMiniDebugInfoInternal<ElfTypes32>(isa,
166 features,
167 text_section_address,
168 text_section_size,
169 dex_section_address,
170 dex_section_size,
171 debug_info);
172 }
173 }
174
MakeElfFileForJIT(InstructionSet isa,const InstructionSetFeatures * features,bool mini_debug_info,const MethodDebugInfo & method_info)175 std::vector<uint8_t> MakeElfFileForJIT(InstructionSet isa,
176 [[maybe_unused]] const InstructionSetFeatures* features,
177 bool mini_debug_info,
178 const MethodDebugInfo& method_info) {
179 using ElfTypes = ElfRuntimeTypes;
180 CHECK_EQ(sizeof(ElfTypes::Addr), static_cast<size_t>(GetInstructionSetPointerSize(isa)));
181 CHECK_EQ(method_info.is_code_address_text_relative, false);
182 DebugInfo debug_info{};
183 debug_info.compiled_methods = ArrayRef<const MethodDebugInfo>(&method_info, 1);
184 std::vector<uint8_t> buffer;
185 buffer.reserve(KB);
186 VectorOutputStream out("Debug ELF file", &buffer);
187 std::unique_ptr<ElfBuilder<ElfTypes>> builder(new ElfBuilder<ElfTypes>(isa, &out));
188 // No program headers since the ELF file is not linked and has no allocated sections.
189 builder->Start(/* write_program_headers= */ false);
190 builder->GetText()->AllocateVirtualMemory(method_info.code_address, method_info.code_size);
191 if (mini_debug_info) {
192 // The compression is great help for multiple methods but it is not worth it for a
193 // single method due to the overheads so skip the compression here for performance.
194 WriteDebugSymbols(builder.get(), /* mini-debug-info= */ true, debug_info);
195 WriteCFISection(builder.get(), debug_info.compiled_methods);
196 } else {
197 WriteDebugInfo(builder.get(), debug_info);
198 }
199 builder->End();
200 CHECK(builder->Good());
201 // Verify the ELF file by reading it back using the trivial reader.
202 if (kIsDebugBuild) {
203 using Elf_Sym = typename ElfTypes::Sym;
204 size_t num_syms = 0;
205 size_t num_cies = 0;
206 size_t num_fdes = 0;
207 using Reader = ElfDebugReader<ElfTypes>;
208 Reader reader(buffer);
209 reader.VisitFunctionSymbols([&](Elf_Sym sym, const char*) {
210 DCHECK_EQ(sym.st_value,
211 method_info.code_address + GetInstructionSetEntryPointAdjustment(isa));
212 DCHECK_EQ(sym.st_size, method_info.code_size);
213 num_syms++;
214 });
215 reader.VisitDebugFrame([&]([[maybe_unused]] const Reader::CIE* cie) { num_cies++; },
216 [&](const Reader::FDE* fde, [[maybe_unused]] const Reader::CIE* cie) {
217 DCHECK_EQ(fde->sym_addr, method_info.code_address);
218 DCHECK_EQ(fde->sym_size, method_info.code_size);
219 num_fdes++;
220 });
221 DCHECK_EQ(num_syms, 1u);
222 DCHECK_LE(num_cies, 1u);
223 DCHECK_LE(num_fdes, 1u);
224 }
225 return buffer;
226 }
227
228 // Combine several mini-debug-info ELF files into one, while filtering some symbols.
PackElfFileForJIT(ArrayRef<const JITCodeEntry * > jit_entries,ArrayRef<const void * > removed_symbols,bool compress,size_t * num_symbols)229 std::vector<uint8_t> PackElfFileForJIT(
230 ArrayRef<const JITCodeEntry*> jit_entries,
231 ArrayRef<const void*> removed_symbols,
232 bool compress,
233 /*out*/ size_t* num_symbols) {
234 using ElfTypes = ElfRuntimeTypes;
235 using Elf_Addr = typename ElfTypes::Addr;
236 using Elf_Sym = typename ElfTypes::Sym;
237 const InstructionSet isa = kRuntimeISA;
238 CHECK_EQ(sizeof(Elf_Addr), static_cast<size_t>(GetInstructionSetPointerSize(isa)));
239 const uint32_t kPcAlign = GetInstructionSetInstructionAlignment(isa);
240 auto is_pc_aligned = [](const void* pc) { return IsAligned<kPcAlign>(pc); };
241 DCHECK(std::all_of(removed_symbols.begin(), removed_symbols.end(), is_pc_aligned));
242 auto is_removed_symbol = [&removed_symbols](Elf_Addr addr) {
243 // Remove thumb-bit, if any (using the fact that address is instruction aligned).
244 const void* code_ptr = AlignDown(reinterpret_cast<const void*>(addr), kPcAlign);
245 return std::binary_search(removed_symbols.begin(), removed_symbols.end(), code_ptr);
246 };
247 uint64_t min_address = std::numeric_limits<uint64_t>::max();
248 uint64_t max_address = 0;
249
250 // Produce the inner ELF file.
251 // It will contain the symbols (.symtab) and unwind information (.debug_frame).
252 std::vector<uint8_t> inner_elf_file;
253 {
254 inner_elf_file.reserve(1 * KB); // Approximate size of ELF file with a single symbol.
255 VectorOutputStream out("Mini-debug-info ELF file for JIT", &inner_elf_file);
256 std::unique_ptr<ElfBuilder<ElfTypes>> builder(new ElfBuilder<ElfTypes>(isa, &out));
257 builder->Start(/*write_program_headers=*/ false);
258 auto* text = builder->GetText();
259 auto* strtab = builder->GetStrTab();
260 auto* symtab = builder->GetSymTab();
261 auto* debug_frame = builder->GetDebugFrame();
262 std::deque<Elf_Sym> symbols;
263
264 using Reader = ElfDebugReader<ElfTypes>;
265 std::deque<Reader> readers;
266 for (const JITCodeEntry* it : jit_entries) {
267 readers.emplace_back(GetJITCodeEntrySymFile(it));
268 }
269
270 // Write symbols names. All other data is buffered.
271 strtab->Start();
272 strtab->Write(""); // strtab should start with empty string.
273 for (Reader& reader : readers) {
274 reader.VisitFunctionSymbols([&](Elf_Sym sym, const char* name) {
275 if (is_removed_symbol(sym.st_value)) {
276 return;
277 }
278 sym.st_name = strtab->Write(name);
279 symbols.push_back(sym);
280 min_address = std::min<uint64_t>(min_address, sym.st_value);
281 max_address = std::max<uint64_t>(max_address, sym.st_value + sym.st_size);
282 });
283 }
284 strtab->End();
285
286 // Create .text covering the code range. Needed for gdb to find the symbols.
287 if (max_address > min_address) {
288 text->AllocateVirtualMemory(min_address, max_address - min_address);
289 }
290
291 // Add the symbols.
292 *num_symbols = symbols.size();
293 for (; !symbols.empty(); symbols.pop_front()) {
294 symtab->Add(symbols.front(), text);
295 }
296 symtab->WriteCachedSection();
297
298 // Add the CFI/unwind section.
299 debug_frame->Start();
300 // ART always produces the same CIE, so we copy the first one and ignore the rest.
301 bool copied_cie = false;
302 for (Reader& reader : readers) {
303 reader.VisitDebugFrame(
304 [&](const Reader::CIE* cie) {
305 if (!copied_cie) {
306 debug_frame->WriteFully(cie->data(), cie->size());
307 copied_cie = true;
308 }
309 },
310 [&](const Reader::FDE* fde, [[maybe_unused]] const Reader::CIE* cie) {
311 DCHECK(copied_cie);
312 DCHECK_EQ(fde->cie_pointer, 0);
313 if (!is_removed_symbol(fde->sym_addr)) {
314 debug_frame->WriteFully(fde->data(), fde->size());
315 }
316 });
317 }
318 debug_frame->End();
319
320 builder->End();
321 CHECK(builder->Good());
322 }
323
324 // Produce the outer ELF file.
325 // It contains only the inner ELF file compressed as .gnu_debugdata section.
326 // This extra wrapping is not necessary but the compression saves space.
327 if (compress) {
328 std::vector<uint8_t> outer_elf_file;
329 std::vector<uint8_t> gnu_debugdata;
330 gnu_debugdata.reserve(inner_elf_file.size() / 4);
331 XzCompress(ArrayRef<const uint8_t>(inner_elf_file), &gnu_debugdata);
332
333 outer_elf_file.reserve(KB + gnu_debugdata.size());
334 VectorOutputStream out("Mini-debug-info ELF file for JIT", &outer_elf_file);
335 std::unique_ptr<ElfBuilder<ElfTypes>> builder(new ElfBuilder<ElfTypes>(isa, &out));
336 builder->Start(/*write_program_headers=*/ false);
337 if (max_address > min_address) {
338 builder->GetText()->AllocateVirtualMemory(min_address, max_address - min_address);
339 }
340 builder->WriteSection(".gnu_debugdata", &gnu_debugdata);
341 builder->End();
342 CHECK(builder->Good());
343 return outer_elf_file;
344 } else {
345 return inner_elf_file;
346 }
347 }
348
WriteDebugElfFileForClasses(InstructionSet isa,const InstructionSetFeatures * features,const ArrayRef<mirror::Class * > & types)349 std::vector<uint8_t> WriteDebugElfFileForClasses(
350 InstructionSet isa,
351 [[maybe_unused]] const InstructionSetFeatures* features,
352 const ArrayRef<mirror::Class*>& types) REQUIRES_SHARED(Locks::mutator_lock_) {
353 using ElfTypes = ElfRuntimeTypes;
354 CHECK_EQ(sizeof(ElfTypes::Addr), static_cast<size_t>(GetInstructionSetPointerSize(isa)));
355 std::vector<uint8_t> buffer;
356 buffer.reserve(KB);
357 VectorOutputStream out("Debug ELF file", &buffer);
358 std::unique_ptr<ElfBuilder<ElfTypes>> builder(new ElfBuilder<ElfTypes>(isa, &out));
359 // No program headers since the ELF file is not linked and has no allocated sections.
360 builder->Start(/* write_program_headers= */ false);
361 ElfDebugInfoWriter<ElfTypes> info_writer(builder.get());
362 info_writer.Start();
363 ElfCompilationUnitWriter<ElfTypes> cu_writer(&info_writer);
364 cu_writer.Write(types);
365 info_writer.End();
366
367 builder->End();
368 CHECK(builder->Good());
369 return buffer;
370 }
371
372 // Explicit instantiations
373 template void WriteDebugInfo<ElfTypes32>(
374 ElfBuilder<ElfTypes32>* builder,
375 const DebugInfo& debug_info);
376 template void WriteDebugInfo<ElfTypes64>(
377 ElfBuilder<ElfTypes64>* builder,
378 const DebugInfo& debug_info);
379
380 } // namespace debug
381 } // namespace art
382