/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "elf_debug_writer.h"
#include <type_traits>
#include <unordered_map>
#include <vector>
#include "base/array_ref.h"
#include "base/stl_util.h"
#include "debug/elf_compilation_unit.h"
#include "debug/elf_debug_frame_writer.h"
#include "debug/elf_debug_info_writer.h"
#include "debug/elf_debug_line_writer.h"
#include "debug/elf_debug_loc_writer.h"
#include "debug/elf_symtab_writer.h"
#include "debug/method_debug_info.h"
#include "dwarf/dwarf_constants.h"
#include "elf/elf_builder.h"
#include "elf/elf_debug_reader.h"
#include "elf/elf_utils.h"
#include "elf/xz_utils.h"
#include "oat.h"
#include "stream/vector_output_stream.h"
namespace art {
namespace debug {
using ElfRuntimeTypes = std::conditional<sizeof(void*) == 4, ElfTypes32, ElfTypes64>::type;
template <typename ElfTypes>
void WriteDebugInfo(ElfBuilder<ElfTypes>* builder,
const DebugInfo& debug_info) {
// Write .strtab and .symtab.
WriteDebugSymbols(builder, /* mini-debug-info= */ false, debug_info);
// Write .debug_frame.
WriteCFISection(builder, debug_info.compiled_methods);
// Group the methods into compilation units based on class.
std::unordered_map<const dex::ClassDef*, ElfCompilationUnit> class_to_compilation_unit;
for (const MethodDebugInfo& mi : debug_info.compiled_methods) {
if (mi.dex_file != nullptr) {
auto& dex_class_def = mi.dex_file->GetClassDef(mi.class_def_index);
ElfCompilationUnit& cu = class_to_compilation_unit[&dex_class_def];
cu.methods.push_back(&mi);
// All methods must have the same addressing mode otherwise the min/max below does not work.
DCHECK_EQ(cu.methods.front()->is_code_address_text_relative, mi.is_code_address_text_relative);
cu.is_code_address_text_relative = mi.is_code_address_text_relative;
cu.code_address = std::min(cu.code_address, mi.code_address);
cu.code_end = std::max(cu.code_end, mi.code_address + mi.code_size);
}
}
// Sort compilation units to make the compiler output deterministic.
std::vector<ElfCompilationUnit> compilation_units;
compilation_units.reserve(class_to_compilation_unit.size());
for (auto& it : class_to_compilation_unit) {
// The .debug_line section requires the methods to be sorted by code address.
std::stable_sort(it.second.methods.begin(),
it.second.methods.end(),
[](const MethodDebugInfo* a, const MethodDebugInfo* b) {
return a->code_address < b->code_address;
});
compilation_units.push_back(std::move(it.second));
}
std::sort(compilation_units.begin(),
compilation_units.end(),
[](ElfCompilationUnit& a, ElfCompilationUnit& b) {
// Sort by index of the first method within the method_infos array.
// This assumes that the order of method_infos is deterministic.
// Code address is not good for sorting due to possible duplicates.
return a.methods.front() < b.methods.front();
});
// Write .debug_line section.
if (!compilation_units.empty()) {
ElfDebugLineWriter<ElfTypes> line_writer(builder);
line_writer.Start();
for (auto& compilation_unit : compilation_units) {
line_writer.WriteCompilationUnit(compilation_unit);
}
line_writer.End();
}
// Write .debug_info section.
if (!compilation_units.empty()) {
ElfDebugInfoWriter<ElfTypes> info_writer(builder);
info_writer.Start();
for (const auto& compilation_unit : compilation_units) {
ElfCompilationUnitWriter<ElfTypes> cu_writer(&info_writer);
cu_writer.Write(compilation_unit);
}
info_writer.End();
}
}
template <typename ElfTypes>
static std::vector<uint8_t> MakeMiniDebugInfoInternal(
InstructionSet isa,
const InstructionSetFeatures* features ATTRIBUTE_UNUSED,
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) {
std::vector<uint8_t> buffer;
buffer.reserve(KB);
VectorOutputStream out("Mini-debug-info ELF file", &buffer);
std::unique_ptr<ElfBuilder<ElfTypes>> builder(new ElfBuilder<ElfTypes>(isa, &out));
builder->Start(/* write_program_headers= */ false);
// Mirror ELF sections as NOBITS since the added symbols will reference them.
if (text_section_size != 0) {
builder->GetText()->AllocateVirtualMemory(text_section_address, text_section_size);
}
if (dex_section_size != 0) {
builder->GetDex()->AllocateVirtualMemory(dex_section_address, dex_section_size);
}
if (!debug_info.Empty()) {
WriteDebugSymbols(builder.get(), /* mini-debug-info= */ true, debug_info);
}
if (!debug_info.compiled_methods.empty()) {
WriteCFISection(builder.get(), debug_info.compiled_methods);
}
builder->End();
CHECK(builder->Good());
std::vector<uint8_t> compressed_buffer;
compressed_buffer.reserve(buffer.size() / 4);
XzCompress(ArrayRef<const uint8_t>(buffer), &compressed_buffer);
return compressed_buffer;
}
std::vector<uint8_t> 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) {
if (Is64BitInstructionSet(isa)) {
return MakeMiniDebugInfoInternal<ElfTypes64>(isa,
features,
text_section_address,
text_section_size,
dex_section_address,
dex_section_size,
debug_info);
} else {
return MakeMiniDebugInfoInternal<ElfTypes32>(isa,
features,
text_section_address,
text_section_size,
dex_section_address,
dex_section_size,
debug_info);
}
}
std::vector<uint8_t> MakeElfFileForJIT(
InstructionSet isa,
const InstructionSetFeatures* features ATTRIBUTE_UNUSED,
bool mini_debug_info,
const MethodDebugInfo& method_info) {
using ElfTypes = ElfRuntimeTypes;
CHECK_EQ(sizeof(ElfTypes::Addr), static_cast<size_t>(GetInstructionSetPointerSize(isa)));
CHECK_EQ(method_info.is_code_address_text_relative, false);
DebugInfo debug_info{};
debug_info.compiled_methods = ArrayRef<const MethodDebugInfo>(&method_info, 1);
std::vector<uint8_t> buffer;
buffer.reserve(KB);
VectorOutputStream out("Debug ELF file", &buffer);
std::unique_ptr<ElfBuilder<ElfTypes>> builder(new ElfBuilder<ElfTypes>(isa, &out));
// No program headers since the ELF file is not linked and has no allocated sections.
builder->Start(/* write_program_headers= */ false);
builder->GetText()->AllocateVirtualMemory(method_info.code_address, method_info.code_size);
if (mini_debug_info) {
// The compression is great help for multiple methods but it is not worth it for a
// single method due to the overheads so skip the compression here for performance.
WriteDebugSymbols(builder.get(), /* mini-debug-info= */ true, debug_info);
WriteCFISection(builder.get(), debug_info.compiled_methods);
} else {
WriteDebugInfo(builder.get(), debug_info);
}
builder->End();
CHECK(builder->Good());
// Verify the ELF file by reading it back using the trivial reader.
if (kIsDebugBuild) {
using Elf_Sym = typename ElfTypes::Sym;
size_t num_syms = 0;
size_t num_cies = 0;
size_t num_fdes = 0;
using Reader = ElfDebugReader<ElfTypes>;
Reader reader(buffer);
reader.VisitFunctionSymbols([&](Elf_Sym sym, const char*) {
DCHECK_EQ(sym.st_value, method_info.code_address + CompiledMethod::CodeDelta(isa));
DCHECK_EQ(sym.st_size, method_info.code_size);
num_syms++;
});
reader.VisitDebugFrame([&](const Reader::CIE* cie ATTRIBUTE_UNUSED) {
num_cies++;
}, [&](const Reader::FDE* fde, const Reader::CIE* cie ATTRIBUTE_UNUSED) {
DCHECK_EQ(fde->sym_addr, method_info.code_address);
DCHECK_EQ(fde->sym_size, method_info.code_size);
num_fdes++;
});
DCHECK_EQ(num_syms, 1u);
DCHECK_LE(num_cies, 1u);
DCHECK_LE(num_fdes, 1u);
}
return buffer;
}
// Combine several mini-debug-info ELF files into one, while filtering some symbols.
std::vector<uint8_t> PackElfFileForJIT(
InstructionSet isa,
const InstructionSetFeatures* features ATTRIBUTE_UNUSED,
std::vector<ArrayRef<const uint8_t>>& added_elf_files,
std::vector<const void*>& removed_symbols,
/*out*/ size_t* num_symbols) {
using ElfTypes = ElfRuntimeTypes;
using Elf_Addr = typename ElfTypes::Addr;
using Elf_Sym = typename ElfTypes::Sym;
CHECK_EQ(sizeof(Elf_Addr), static_cast<size_t>(GetInstructionSetPointerSize(isa)));
auto is_removed_symbol = [&removed_symbols](Elf_Addr addr) {
const void* code_ptr = reinterpret_cast<const void*>(addr);
return std::binary_search(removed_symbols.begin(), removed_symbols.end(), code_ptr);
};
uint64_t min_address = std::numeric_limits<uint64_t>::max();
uint64_t max_address = 0;
// Produce the inner ELF file.
// It will contain the symbols (.symtab) and unwind information (.debug_frame).
std::vector<uint8_t> inner_elf_file;
{
inner_elf_file.reserve(1 * KB); // Approximate size of ELF file with a single symbol.
VectorOutputStream out("Mini-debug-info ELF file for JIT", &inner_elf_file);
std::unique_ptr<ElfBuilder<ElfTypes>> builder(new ElfBuilder<ElfTypes>(isa, &out));
builder->Start(/*write_program_headers=*/ false);
auto* text = builder->GetText();
auto* strtab = builder->GetStrTab();
auto* symtab = builder->GetSymTab();
auto* debug_frame = builder->GetDebugFrame();
std::deque<Elf_Sym> symbols;
using Reader = ElfDebugReader<ElfTypes>;
std::deque<Reader> readers;
for (ArrayRef<const uint8_t> added_elf_file : added_elf_files) {
readers.emplace_back(added_elf_file);
}
// Write symbols names. All other data is buffered.
strtab->Start();
strtab->Write(""); // strtab should start with empty string.
for (Reader& reader : readers) {
reader.VisitFunctionSymbols([&](Elf_Sym sym, const char* name) {
if (is_removed_symbol(sym.st_value)) {
return;
}
sym.st_name = strtab->Write(name);
symbols.push_back(sym);
min_address = std::min<uint64_t>(min_address, sym.st_value);
max_address = std::max<uint64_t>(max_address, sym.st_value + sym.st_size);
});
}
strtab->End();
// Create .text covering the code range. Needed for gdb to find the symbols.
if (max_address > min_address) {
text->AllocateVirtualMemory(min_address, max_address - min_address);
}
// Add the symbols.
*num_symbols = symbols.size();
for (; !symbols.empty(); symbols.pop_front()) {
symtab->Add(symbols.front(), text);
}
symtab->WriteCachedSection();
// Add the CFI/unwind section.
debug_frame->Start();
// ART always produces the same CIE, so we copy the first one and ignore the rest.
bool copied_cie = false;
for (Reader& reader : readers) {
reader.VisitDebugFrame([&](const Reader::CIE* cie) {
if (!copied_cie) {
debug_frame->WriteFully(cie->data(), cie->size());
copied_cie = true;
}
}, [&](const Reader::FDE* fde, const Reader::CIE* cie ATTRIBUTE_UNUSED) {
DCHECK(copied_cie);
DCHECK_EQ(fde->cie_pointer, 0);
if (!is_removed_symbol(fde->sym_addr)) {
debug_frame->WriteFully(fde->data(), fde->size());
}
});
}
debug_frame->End();
builder->End();
CHECK(builder->Good());
}
// Produce the outer ELF file.
// It contains only the inner ELF file compressed as .gnu_debugdata section.
// This extra wrapping is not necessary but the compression saves space.
std::vector<uint8_t> outer_elf_file;
{
std::vector<uint8_t> gnu_debugdata;
gnu_debugdata.reserve(inner_elf_file.size() / 4);
XzCompress(ArrayRef<const uint8_t>(inner_elf_file), &gnu_debugdata);
outer_elf_file.reserve(KB + gnu_debugdata.size());
VectorOutputStream out("Mini-debug-info ELF file for JIT", &outer_elf_file);
std::unique_ptr<ElfBuilder<ElfTypes>> builder(new ElfBuilder<ElfTypes>(isa, &out));
builder->Start(/*write_program_headers=*/ false);
if (max_address > min_address) {
builder->GetText()->AllocateVirtualMemory(min_address, max_address - min_address);
}
builder->WriteSection(".gnu_debugdata", &gnu_debugdata);
builder->End();
CHECK(builder->Good());
}
return outer_elf_file;
}
std::vector<uint8_t> WriteDebugElfFileForClasses(
InstructionSet isa,
const InstructionSetFeatures* features ATTRIBUTE_UNUSED,
const ArrayRef<mirror::Class*>& types)
REQUIRES_SHARED(Locks::mutator_lock_) {
using ElfTypes = ElfRuntimeTypes;
CHECK_EQ(sizeof(ElfTypes::Addr), static_cast<size_t>(GetInstructionSetPointerSize(isa)));
std::vector<uint8_t> buffer;
buffer.reserve(KB);
VectorOutputStream out("Debug ELF file", &buffer);
std::unique_ptr<ElfBuilder<ElfTypes>> builder(new ElfBuilder<ElfTypes>(isa, &out));
// No program headers since the ELF file is not linked and has no allocated sections.
builder->Start(/* write_program_headers= */ false);
ElfDebugInfoWriter<ElfTypes> info_writer(builder.get());
info_writer.Start();
ElfCompilationUnitWriter<ElfTypes> cu_writer(&info_writer);
cu_writer.Write(types);
info_writer.End();
builder->End();
CHECK(builder->Good());
return buffer;
}
// Explicit instantiations
template void WriteDebugInfo<ElfTypes32>(
ElfBuilder<ElfTypes32>* builder,
const DebugInfo& debug_info);
template void WriteDebugInfo<ElfTypes64>(
ElfBuilder<ElfTypes64>* builder,
const DebugInfo& debug_info);
} // namespace debug
} // namespace art