Generate .eh_frame_hdr section and PT_GNU_EH_FRAME segment.
Fixes issue 20125400 - ART: Need .eh_frame_hdr and PT_GNU_EH_FRAME
for libunwind.
.eh_frame_hdr serves two purposes. Firstly, it can optionally contain
binary search table for fast eh_frame lookup. This is important for
C++ exception handling, but we do not need it so we omit it.
Secondly, it contains a relative .eh_frame pointer which makes it
easier for run-time code to locate the .eh_frame section.
libunwind seems to rely on this relative pointer.
Bug: 20125400
Change-Id: I7c1e3f68d914f70781404c508395831a3296a7da
diff --git a/compiler/elf_writer_debug.cc b/compiler/elf_writer_debug.cc
index 39233ce..cf0adae 100644
--- a/compiler/elf_writer_debug.cc
+++ b/compiler/elf_writer_debug.cc
@@ -28,7 +28,9 @@
namespace art {
namespace dwarf {
-static void WriteEhFrameCIE(InstructionSet isa, std::vector<uint8_t>* eh_frame) {
+static void WriteEhFrameCIE(InstructionSet isa,
+ ExceptionHeaderValueApplication addr_type,
+ std::vector<uint8_t>* eh_frame) {
// 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);
@@ -53,8 +55,8 @@
opcodes.SameValue(Reg::ArmFp(reg));
}
}
- auto return_address_reg = Reg::ArmCore(14); // R14(LR).
- WriteEhFrameCIE(is64bit, return_address_reg, opcodes, eh_frame);
+ auto return_reg = Reg::ArmCore(14); // R14(LR).
+ WriteEhFrameCIE(is64bit, addr_type, return_reg, opcodes, eh_frame);
return;
}
case kArm64: {
@@ -76,8 +78,8 @@
opcodes.SameValue(Reg::Arm64Fp(reg));
}
}
- auto return_address_reg = Reg::Arm64Core(30); // R30(LR).
- WriteEhFrameCIE(is64bit, return_address_reg, opcodes, eh_frame);
+ auto return_reg = Reg::Arm64Core(30); // R30(LR).
+ WriteEhFrameCIE(is64bit, addr_type, return_reg, opcodes, eh_frame);
return;
}
case kMips:
@@ -92,8 +94,8 @@
opcodes.SameValue(Reg::MipsCore(reg));
}
}
- auto return_address_reg = Reg::MipsCore(31); // R31(RA).
- WriteEhFrameCIE(is64bit, return_address_reg, opcodes, eh_frame);
+ auto return_reg = Reg::MipsCore(31); // R31(RA).
+ WriteEhFrameCIE(is64bit, addr_type, return_reg, opcodes, eh_frame);
return;
}
case kX86: {
@@ -114,8 +116,8 @@
for (int reg = 0; reg < 8; reg++) {
opcodes.Undefined(Reg::X86Fp(reg));
}
- auto return_address_reg = Reg::X86Core(8); // R8(EIP).
- WriteEhFrameCIE(is64bit, return_address_reg, opcodes, eh_frame);
+ auto return_reg = Reg::X86Core(8); // R8(EIP).
+ WriteEhFrameCIE(is64bit, addr_type, return_reg, opcodes, eh_frame);
return;
}
case kX86_64: {
@@ -140,8 +142,8 @@
opcodes.SameValue(Reg::X86_64Fp(reg));
}
}
- auto return_address_reg = Reg::X86_64Core(16); // R16(RIP).
- WriteEhFrameCIE(is64bit, return_address_reg, opcodes, eh_frame);
+ auto return_reg = Reg::X86_64Core(16); // R16(RIP).
+ WriteEhFrameCIE(is64bit, addr_type, return_reg, opcodes, eh_frame);
return;
}
case kNone:
@@ -152,22 +154,37 @@
}
void WriteEhFrame(const CompilerDriver* compiler,
- OatWriter* oat_writer,
- uint32_t text_section_offset,
- std::vector<uint8_t>* eh_frame) {
+ const OatWriter* oat_writer,
+ ExceptionHeaderValueApplication address_type,
+ std::vector<uint8_t>* eh_frame,
+ std::vector<uintptr_t>* eh_frame_patches,
+ std::vector<uint8_t>* eh_frame_hdr) {
const auto& method_infos = oat_writer->GetMethodDebugInfo();
const InstructionSet isa = compiler->GetInstructionSet();
+
+ // Write .eh_frame section.
size_t cie_offset = eh_frame->size();
- auto* eh_frame_patches = oat_writer->GetAbsolutePatchLocationsFor(".eh_frame");
- WriteEhFrameCIE(isa, eh_frame);
+ WriteEhFrameCIE(isa, address_type, eh_frame);
for (const OatWriter::DebugInfo& mi : method_infos) {
const SwapVector<uint8_t>* opcodes = mi.compiled_method_->GetCFIInfo();
if (opcodes != nullptr) {
WriteEhFrameFDE(Is64BitInstructionSet(isa), cie_offset,
- text_section_offset + mi.low_pc_, mi.high_pc_ - mi.low_pc_,
+ mi.low_pc_, mi.high_pc_ - mi.low_pc_,
opcodes, eh_frame, eh_frame_patches);
}
}
+
+ // Write .eh_frame_hdr section.
+ Writer<> header(eh_frame_hdr);
+ header.PushUint8(1); // Version.
+ header.PushUint8(DW_EH_PE_pcrel | DW_EH_PE_sdata4); // Encoding of .eh_frame pointer.
+ header.PushUint8(DW_EH_PE_omit); // Encoding of binary search table size.
+ header.PushUint8(DW_EH_PE_omit); // Encoding of binary search table addresses.
+ // .eh_frame pointer - .eh_frame_hdr section is after .eh_frame section, and need to encode
+ // relative to this location as libunwind doesn't honor datarel for eh_frame_hdr correctly.
+ header.PushInt32(-static_cast<int32_t>(eh_frame->size() + 4U));
+ // Omit binary search table size (number of entries).
+ // Omit binary search table.
}
/*
@@ -175,17 +192,20 @@
* @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,
- OatWriter* oat_writer,
- uint32_t text_section_offset,
+ 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<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();
@@ -229,8 +249,8 @@
info.StartTag(DW_TAG_compile_unit, DW_CHILDREN_yes);
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 + text_section_offset);
- info.WriteAddr(DW_AT_high_pc, cunit_high_pc + text_section_offset);
+ 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());
for (auto method_info : compilation_unit) {
std::string method_name = PrettyMethod(method_info->dex_method_index_,
@@ -240,12 +260,11 @@
}
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_ + text_section_offset);
- info.WriteAddr(DW_AT_high_pc, method_info->high_pc_ + text_section_offset);
+ info.WriteAddr(DW_AT_low_pc, method_info->low_pc_);
+ info.WriteAddr(DW_AT_high_pc, method_info->high_pc_);
info.EndTag(); // DW_TAG_subprogram
}
info.EndTag(); // DW_TAG_compile_unit
- auto* debug_info_patches = oat_writer->GetAbsolutePatchLocationsFor(".debug_info");
WriteDebugInfoCU(debug_abbrev_offset, info, debug_info, debug_info_patches);
// Write .debug_line section.
@@ -272,7 +291,7 @@
break;
}
DebugLineOpCodeWriter<> opcodes(false /* 32bit */, code_factor_bits_);
- opcodes.SetAddress(text_section_offset + cunit_low_pc);
+ opcodes.SetAddress(cunit_low_pc);
if (dwarf_isa != -1) {
opcodes.SetISA(dwarf_isa);
}
@@ -343,7 +362,6 @@
// Generate mapping opcodes from PC to Java lines.
const DefaultSrcMap& dex2line_map = debug_info_callbacks.dex2line_;
- uint32_t low_pc = text_section_offset + mi->low_pc_;
if (file_index != 0 && !dex2line_map.empty()) {
bool first = true;
for (SrcMapElem pc2dex : mi->compiled_method_->GetSrcMappingTable()) {
@@ -359,24 +377,23 @@
int first_line = dex2line_map.front().to_;
// Prologue is not a sensible place for a breakpoint.
opcodes.NegateStmt();
- opcodes.AddRow(low_pc, first_line);
+ opcodes.AddRow(mi->low_pc_, first_line);
opcodes.NegateStmt();
opcodes.SetPrologueEnd();
}
- opcodes.AddRow(low_pc + pc, line);
+ opcodes.AddRow(mi->low_pc_ + pc, line);
} else if (line != opcodes.CurrentLine()) {
- opcodes.AddRow(low_pc + pc, line);
+ opcodes.AddRow(mi->low_pc_ + pc, line);
}
}
}
} else {
// line 0 - instruction cannot be attributed to any source line.
- opcodes.AddRow(low_pc, 0);
+ opcodes.AddRow(mi->low_pc_, 0);
}
}
- opcodes.AdvancePC(text_section_offset + cunit_high_pc);
+ opcodes.AdvancePC(cunit_high_pc);
opcodes.EndSequence();
- auto* debug_line_patches = oat_writer->GetAbsolutePatchLocationsFor(".debug_line");
WriteDebugLineTable(directories, files, opcodes, debug_line, debug_line_patches);
}
}