Rewrite ElfBuilder to make streaming directly to file easier.
The previous design required knowing all the sections and their
sizes before even the first byte of the file was written.
The new design allows sections to be written one by one without
any knowledge of later sections. Furthermore, as soon as
section is started, its virtual memory address is known,
which removes the need for the various patching passes.
The new ElfBuilder essentially tries to be a thin wrapper
around OutputStream which keeps track where the various
sections start/end and then writes their ELF headers.
Change-Id: I817e7f3b41882e4e4b9b442cfe56e4ef2e26babd
diff --git a/compiler/elf_writer_debug.cc b/compiler/elf_writer_debug.cc
index 3a9e312..90db7eb 100644
--- a/compiler/elf_writer_debug.cc
+++ b/compiler/elf_writer_debug.cc
@@ -24,16 +24,16 @@
#include "dex_file-inl.h"
#include "dwarf/headers.h"
#include "dwarf/register.h"
+#include "elf_builder.h"
#include "oat_writer.h"
#include "utils.h"
namespace art {
namespace dwarf {
-static void WriteDebugFrameCIE(InstructionSet isa,
- ExceptionHeaderValueApplication addr_type,
- CFIFormat format,
- std::vector<uint8_t>* eh_frame) {
+static void WriteCIE(InstructionSet isa,
+ CFIFormat format,
+ std::vector<uint8_t>* buffer) {
// Scratch registers should be marked as undefined. This tells the
// debugger that its value in the previous frame is not recoverable.
bool is64bit = Is64BitInstructionSet(isa);
@@ -59,8 +59,7 @@
}
}
auto return_reg = Reg::ArmCore(14); // R14(LR).
- WriteDebugFrameCIE(is64bit, addr_type, return_reg,
- opcodes, format, eh_frame);
+ WriteCIE(is64bit, return_reg, opcodes, format, buffer);
return;
}
case kArm64: {
@@ -83,8 +82,7 @@
}
}
auto return_reg = Reg::Arm64Core(30); // R30(LR).
- WriteDebugFrameCIE(is64bit, addr_type, return_reg,
- opcodes, format, eh_frame);
+ WriteCIE(is64bit, return_reg, opcodes, format, buffer);
return;
}
case kMips:
@@ -100,8 +98,7 @@
}
}
auto return_reg = Reg::MipsCore(31); // R31(RA).
- WriteDebugFrameCIE(is64bit, addr_type, return_reg,
- opcodes, format, eh_frame);
+ WriteCIE(is64bit, return_reg, opcodes, format, buffer);
return;
}
case kX86: {
@@ -127,8 +124,7 @@
}
}
auto return_reg = Reg::X86Core(8); // R8(EIP).
- WriteDebugFrameCIE(is64bit, addr_type, return_reg,
- opcodes, format, eh_frame);
+ WriteCIE(is64bit, return_reg, opcodes, format, buffer);
return;
}
case kX86_64: {
@@ -154,8 +150,7 @@
}
}
auto return_reg = Reg::X86_64Core(16); // R16(RIP).
- WriteDebugFrameCIE(is64bit, addr_type, return_reg,
- opcodes, format, eh_frame);
+ WriteCIE(is64bit, return_reg, opcodes, format, buffer);
return;
}
case kNone:
@@ -165,36 +160,69 @@
UNREACHABLE();
}
-void WriteCFISection(const CompilerDriver* compiler,
- const OatWriter* oat_writer,
- ExceptionHeaderValueApplication address_type,
- CFIFormat format,
- std::vector<uint8_t>* debug_frame,
- std::vector<uintptr_t>* debug_frame_patches,
- std::vector<uint8_t>* eh_frame_hdr,
- std::vector<uintptr_t>* eh_frame_hdr_patches) {
- const auto& method_infos = oat_writer->GetMethodDebugInfo();
- const InstructionSet isa = compiler->GetInstructionSet();
+template<typename ElfTypes>
+void WriteCFISection(ElfBuilder<ElfTypes>* builder,
+ const std::vector<OatWriter::DebugInfo>& method_infos,
+ CFIFormat format) {
+ CHECK(format == dwarf::DW_DEBUG_FRAME_FORMAT ||
+ format == dwarf::DW_EH_FRAME_FORMAT);
+ typedef typename ElfTypes::Addr Elf_Addr;
+
+ std::vector<uint32_t> binary_search_table;
+ std::vector<uintptr_t> patch_locations;
+ if (format == DW_EH_FRAME_FORMAT) {
+ binary_search_table.reserve(2 * method_infos.size());
+ } else {
+ patch_locations.reserve(method_infos.size());
+ }
// Write .eh_frame/.debug_frame section.
- std::map<uint32_t, size_t> address_to_fde_offset_map;
- size_t cie_offset = debug_frame->size();
- WriteDebugFrameCIE(isa, address_type, format, debug_frame);
- for (const OatWriter::DebugInfo& mi : method_infos) {
- if (!mi.deduped_) { // Only one FDE per unique address.
- ArrayRef<const uint8_t> opcodes = mi.compiled_method_->GetCFIInfo();
- if (!opcodes.empty()) {
- address_to_fde_offset_map.emplace(mi.low_pc_, debug_frame->size());
- WriteDebugFrameFDE(Is64BitInstructionSet(isa), cie_offset,
- mi.low_pc_, mi.high_pc_ - mi.low_pc_,
- opcodes, format, debug_frame, debug_frame_patches);
+ auto* cfi_section = (format == dwarf::DW_DEBUG_FRAME_FORMAT
+ ? builder->GetDebugFrame()
+ : builder->GetEhFrame());
+ {
+ cfi_section->Start();
+ const bool is64bit = Is64BitInstructionSet(builder->GetIsa());
+ const Elf_Addr text_address = builder->GetText()->GetAddress();
+ const Elf_Addr cfi_address = cfi_section->GetAddress();
+ const Elf_Addr cie_address = cfi_address;
+ Elf_Addr buffer_address = cfi_address;
+ std::vector<uint8_t> buffer; // Small temporary buffer.
+ WriteCIE(builder->GetIsa(), format, &buffer);
+ cfi_section->WriteFully(buffer.data(), buffer.size());
+ buffer_address += buffer.size();
+ buffer.clear();
+ for (const OatWriter::DebugInfo& mi : method_infos) {
+ if (!mi.deduped_) { // Only one FDE per unique address.
+ ArrayRef<const uint8_t> opcodes = mi.compiled_method_->GetCFIInfo();
+ if (!opcodes.empty()) {
+ const Elf_Addr code_address = text_address + mi.low_pc_;
+ if (format == DW_EH_FRAME_FORMAT) {
+ binary_search_table.push_back(
+ dchecked_integral_cast<uint32_t>(code_address));
+ binary_search_table.push_back(
+ dchecked_integral_cast<uint32_t>(buffer_address));
+ }
+ WriteFDE(is64bit, cfi_address, cie_address,
+ code_address, mi.high_pc_ - mi.low_pc_,
+ opcodes, format, buffer_address, &buffer,
+ &patch_locations);
+ cfi_section->WriteFully(buffer.data(), buffer.size());
+ buffer_address += buffer.size();
+ buffer.clear();
+ }
}
}
+ cfi_section->End();
}
if (format == DW_EH_FRAME_FORMAT) {
+ auto* header_section = builder->GetEhFrameHdr();
+ header_section->Start();
+ uint32_t header_address = dchecked_integral_cast<int32_t>(header_section->GetAddress());
// Write .eh_frame_hdr section.
- Writer<> header(eh_frame_hdr);
+ std::vector<uint8_t> buffer;
+ Writer<> header(&buffer);
header.PushUint8(1); // Version.
// Encoding of .eh_frame pointer - libunwind does not honor datarel here,
// so we have to use pcrel which means relative to the pointer's location.
@@ -204,47 +232,29 @@
// Encoding of binary search table addresses - libunwind supports only this
// specific combination, which means relative to the start of .eh_frame_hdr.
header.PushUint8(DW_EH_PE_datarel | DW_EH_PE_sdata4);
- // .eh_frame pointer - .eh_frame_hdr section is after .eh_frame section
- const int32_t relative_eh_frame_begin = -static_cast<int32_t>(debug_frame->size());
- header.PushInt32(relative_eh_frame_begin - 4U);
+ // .eh_frame pointer
+ header.PushInt32(cfi_section->GetAddress() - (header_address + 4u));
// Binary search table size (number of entries).
- header.PushUint32(dchecked_integral_cast<uint32_t>(address_to_fde_offset_map.size()));
+ header.PushUint32(dchecked_integral_cast<uint32_t>(binary_search_table.size()/2));
+ header_section->WriteFully(buffer.data(), buffer.size());
// Binary search table.
- for (const auto& address_to_fde_offset : address_to_fde_offset_map) {
- u_int32_t code_address = address_to_fde_offset.first;
- int32_t fde_address = dchecked_integral_cast<int32_t>(address_to_fde_offset.second);
- eh_frame_hdr_patches->push_back(header.data()->size());
- header.PushUint32(code_address);
- // We know the exact layout (eh_frame is immediately before eh_frame_hdr)
- // and the data is relative to the start of the eh_frame_hdr,
- // so patching isn't necessary (in contrast to the code address above).
- header.PushInt32(relative_eh_frame_begin + fde_address);
+ for (size_t i = 0; i < binary_search_table.size(); i++) {
+ // Make addresses section-relative since we know the header address now.
+ binary_search_table[i] -= header_address;
}
+ header_section->WriteFully(binary_search_table.data(), binary_search_table.size());
+ header_section->End();
+ } else {
+ builder->WritePatches(".debug_frame.oat_patches", &patch_locations);
}
}
-/*
- * @brief Generate the DWARF sections.
- * @param oat_writer The Oat file Writer.
- * @param eh_frame Call Frame Information.
- * @param debug_info Compilation unit information.
- * @param debug_info_patches Address locations to be patched.
- * @param debug_abbrev Abbreviations used to generate dbg_info.
- * @param debug_str Debug strings.
- * @param debug_line Line number table.
- * @param debug_line_patches Address locations to be patched.
- */
-void WriteDebugSections(const CompilerDriver* compiler,
- const OatWriter* oat_writer,
- std::vector<uint8_t>* debug_info,
- std::vector<uintptr_t>* debug_info_patches,
- std::vector<uint8_t>* debug_abbrev,
- std::vector<uint8_t>* debug_str,
- std::vector<uint8_t>* debug_line,
- std::vector<uintptr_t>* debug_line_patches) {
- const std::vector<OatWriter::DebugInfo>& method_infos = oat_writer->GetMethodDebugInfo();
- const InstructionSet isa = compiler->GetInstructionSet();
- const bool is64bit = Is64BitInstructionSet(isa);
+template<typename ElfTypes>
+void WriteDebugSections(ElfBuilder<ElfTypes>* builder,
+ const std::vector<OatWriter::DebugInfo>& method_infos) {
+ typedef typename ElfTypes::Addr Elf_Addr;
+ const bool is64bit = Is64BitInstructionSet(builder->GetIsa());
+ Elf_Addr text_address = builder->GetText()->GetAddress();
// Find all addresses (low_pc) which contain deduped methods.
// The first instance of method is not marked deduped_, but the rest is.
@@ -273,6 +283,12 @@
}
// Write .debug_info section.
+ std::vector<uint8_t> debug_info;
+ std::vector<uintptr_t> debug_info_patches;
+ std::vector<uint8_t> debug_abbrev;
+ std::vector<uint8_t> debug_str;
+ std::vector<uint8_t> debug_line;
+ std::vector<uintptr_t> debug_line_patches;
for (const auto& compilation_unit : compilation_units) {
uint32_t cunit_low_pc = 0xFFFFFFFFU;
uint32_t cunit_high_pc = 0;
@@ -281,14 +297,14 @@
cunit_high_pc = std::max(cunit_high_pc, method_info->high_pc_);
}
- size_t debug_abbrev_offset = debug_abbrev->size();
- DebugInfoEntryWriter<> info(is64bit, debug_abbrev);
+ size_t debug_abbrev_offset = debug_abbrev.size();
+ DebugInfoEntryWriter<> info(is64bit, &debug_abbrev);
info.StartTag(DW_TAG_compile_unit, DW_CHILDREN_yes);
- info.WriteStrp(DW_AT_producer, "Android dex2oat", debug_str);
+ info.WriteStrp(DW_AT_producer, "Android dex2oat", &debug_str);
info.WriteData1(DW_AT_language, DW_LANG_Java);
- info.WriteAddr(DW_AT_low_pc, cunit_low_pc);
- info.WriteAddr(DW_AT_high_pc, cunit_high_pc);
- info.WriteData4(DW_AT_stmt_list, debug_line->size());
+ info.WriteAddr(DW_AT_low_pc, text_address + cunit_low_pc);
+ info.WriteAddr(DW_AT_high_pc, text_address + cunit_high_pc);
+ info.WriteData4(DW_AT_stmt_list, debug_line.size());
for (auto method_info : compilation_unit) {
std::string method_name = PrettyMethod(method_info->dex_method_index_,
*method_info->dex_file_, true);
@@ -296,13 +312,13 @@
method_name += " [DEDUPED]";
}
info.StartTag(DW_TAG_subprogram, DW_CHILDREN_no);
- info.WriteStrp(DW_AT_name, method_name.data(), debug_str);
- info.WriteAddr(DW_AT_low_pc, method_info->low_pc_);
- info.WriteAddr(DW_AT_high_pc, method_info->high_pc_);
+ info.WriteStrp(DW_AT_name, method_name.data(), &debug_str);
+ info.WriteAddr(DW_AT_low_pc, text_address + method_info->low_pc_);
+ info.WriteAddr(DW_AT_high_pc, text_address + method_info->high_pc_);
info.EndTag(); // DW_TAG_subprogram
}
info.EndTag(); // DW_TAG_compile_unit
- WriteDebugInfoCU(debug_abbrev_offset, info, debug_info, debug_info_patches);
+ WriteDebugInfoCU(debug_abbrev_offset, info, &debug_info, &debug_info_patches);
// Write .debug_line section.
std::vector<FileEntry> files;
@@ -311,7 +327,7 @@
std::unordered_map<std::string, size_t> directories_map;
int code_factor_bits_ = 0;
int dwarf_isa = -1;
- switch (isa) {
+ switch (builder->GetIsa()) {
case kArm: // arm actually means thumb2.
case kThumb2:
code_factor_bits_ = 1; // 16-bit instuctions
@@ -328,7 +344,7 @@
break;
}
DebugLineOpCodeWriter<> opcodes(is64bit, code_factor_bits_);
- opcodes.SetAddress(cunit_low_pc);
+ opcodes.SetAddress(text_address + cunit_low_pc);
if (dwarf_isa != -1) {
opcodes.SetISA(dwarf_isa);
}
@@ -342,6 +358,8 @@
DefaultSrcMap dex2line_;
} debug_info_callbacks;
+ Elf_Addr method_address = text_address + mi->low_pc_;
+
const DexFile* dex = mi->dex_file_;
if (mi->code_item_ != nullptr) {
dex->DecodeDebugInfo(mi->code_item_,
@@ -414,26 +432,48 @@
int first_line = dex2line_map.front().to_;
// Prologue is not a sensible place for a breakpoint.
opcodes.NegateStmt();
- opcodes.AddRow(mi->low_pc_, first_line);
+ opcodes.AddRow(method_address, first_line);
opcodes.NegateStmt();
opcodes.SetPrologueEnd();
}
- opcodes.AddRow(mi->low_pc_ + pc, line);
+ opcodes.AddRow(method_address + pc, line);
} else if (line != opcodes.CurrentLine()) {
- opcodes.AddRow(mi->low_pc_ + pc, line);
+ opcodes.AddRow(method_address + pc, line);
}
}
}
} else {
// line 0 - instruction cannot be attributed to any source line.
- opcodes.AddRow(mi->low_pc_, 0);
+ opcodes.AddRow(method_address, 0);
}
}
- opcodes.AdvancePC(cunit_high_pc);
+ opcodes.AdvancePC(text_address + cunit_high_pc);
opcodes.EndSequence();
- WriteDebugLineTable(directories, files, opcodes, debug_line, debug_line_patches);
+ WriteDebugLineTable(directories, files, opcodes, &debug_line, &debug_line_patches);
}
+ builder->WriteSection(".debug_info", &debug_info);
+ builder->WritePatches(".debug_info.oat_patches", &debug_info_patches);
+ builder->WriteSection(".debug_abbrev", &debug_abbrev);
+ builder->WriteSection(".debug_str", &debug_str);
+ builder->WriteSection(".debug_line", &debug_line);
+ builder->WritePatches(".debug_line.oat_patches", &debug_line_patches);
}
+// Explicit instantiations
+template void WriteCFISection<ElfTypes32>(
+ ElfBuilder<ElfTypes32>* builder,
+ const std::vector<OatWriter::DebugInfo>& method_infos,
+ CFIFormat format);
+template void WriteCFISection<ElfTypes64>(
+ ElfBuilder<ElfTypes64>* builder,
+ const std::vector<OatWriter::DebugInfo>& method_infos,
+ CFIFormat format);
+template void WriteDebugSections<ElfTypes32>(
+ ElfBuilder<ElfTypes32>* builder,
+ const std::vector<OatWriter::DebugInfo>& method_infos);
+template void WriteDebugSections<ElfTypes64>(
+ ElfBuilder<ElfTypes64>* builder,
+ const std::vector<OatWriter::DebugInfo>& method_infos);
+
} // namespace dwarf
} // namespace art