c44c142afc
By separating the Unwind table into a different file, this functionality can be a part of the DWARF library with no dependency on MC, which makes it usable in the MC layer. This is a continuation of [PR#14520](https://github.com/llvm/llvm-project/pull/142520).
415 lines
16 KiB
C++
415 lines
16 KiB
C++
//===- DWARFDebugFrame.h - Parsing of .debug_frame ------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/DebugInfo/DWARF/DWARFDebugFrame.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/BinaryFormat/Dwarf.h"
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#include "llvm/DebugInfo/DIContext.h"
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#include "llvm/DebugInfo/DWARF/DWARFCFIPrinter.h"
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#include "llvm/DebugInfo/DWARF/DWARFDataExtractor.h"
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#include "llvm/DebugInfo/DWARF/DWARFExpressionPrinter.h"
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#include "llvm/DebugInfo/DWARF/DWARFUnwindTablePrinter.h"
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#include "llvm/DebugInfo/DWARF/LowLevel/DWARFCFIProgram.h"
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#include "llvm/DebugInfo/DWARF/LowLevel/DWARFExpression.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/DataExtractor.h"
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#include "llvm/Support/Errc.h"
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#include "llvm/Support/Error.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/Format.h"
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#include "llvm/Support/raw_ostream.h"
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#include <cassert>
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#include <cinttypes>
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#include <cstdint>
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#include <optional>
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using namespace llvm;
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using namespace dwarf;
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Expected<UnwindTable> llvm::dwarf::createUnwindTable(const FDE *Fde) {
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const CIE *Cie = Fde->getLinkedCIE();
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if (Cie == nullptr)
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return createStringError(errc::invalid_argument,
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"unable to get CIE for FDE at offset 0x%" PRIx64,
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Fde->getOffset());
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// Rows will be empty if there are no CFI instructions.
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if (Cie->cfis().empty() && Fde->cfis().empty())
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return UnwindTable({});
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UnwindTable::RowContainer CieRows;
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UnwindRow Row;
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Row.setAddress(Fde->getInitialLocation());
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if (Error CieError = parseRows(Cie->cfis(), Row, nullptr).moveInto(CieRows))
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return std::move(CieError);
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// We need to save the initial locations of registers from the CIE parsing
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// in case we run into DW_CFA_restore or DW_CFA_restore_extended opcodes.
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UnwindTable::RowContainer FdeRows;
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const RegisterLocations InitialLocs = Row.getRegisterLocations();
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if (Error FdeError =
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parseRows(Fde->cfis(), Row, &InitialLocs).moveInto(FdeRows))
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return std::move(FdeError);
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UnwindTable::RowContainer AllRows;
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AllRows.insert(AllRows.end(), CieRows.begin(), CieRows.end());
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AllRows.insert(AllRows.end(), FdeRows.begin(), FdeRows.end());
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// May be all the CFI instructions were DW_CFA_nop amd Row becomes empty.
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// Do not add that to the unwind table.
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if (Row.getRegisterLocations().hasLocations() ||
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Row.getCFAValue().getLocation() != UnwindLocation::Unspecified)
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AllRows.push_back(Row);
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return UnwindTable(std::move(AllRows));
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}
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Expected<UnwindTable> llvm::dwarf::createUnwindTable(const CIE *Cie) {
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// Rows will be empty if there are no CFI instructions.
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if (Cie->cfis().empty())
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return UnwindTable({});
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UnwindTable::RowContainer Rows;
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UnwindRow Row;
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if (Error CieError = parseRows(Cie->cfis(), Row, nullptr).moveInto(Rows))
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return std::move(CieError);
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// May be all the CFI instructions were DW_CFA_nop amd Row becomes empty.
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// Do not add that to the unwind table.
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if (Row.getRegisterLocations().hasLocations() ||
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Row.getCFAValue().getLocation() != UnwindLocation::Unspecified)
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Rows.push_back(Row);
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return UnwindTable(std::move(Rows));
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}
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// Returns the CIE identifier to be used by the requested format.
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// CIE ids for .debug_frame sections are defined in Section 7.24 of DWARFv5.
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// For CIE ID in .eh_frame sections see
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// https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html
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constexpr uint64_t getCIEId(bool IsDWARF64, bool IsEH) {
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if (IsEH)
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return 0;
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if (IsDWARF64)
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return DW64_CIE_ID;
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return DW_CIE_ID;
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}
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void CIE::dump(raw_ostream &OS, DIDumpOptions DumpOpts) const {
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// A CIE with a zero length is a terminator entry in the .eh_frame section.
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if (DumpOpts.IsEH && Length == 0) {
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OS << format("%08" PRIx64, Offset) << " ZERO terminator\n";
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return;
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}
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OS << format("%08" PRIx64, Offset)
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<< format(" %0*" PRIx64, IsDWARF64 ? 16 : 8, Length)
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<< format(" %0*" PRIx64, IsDWARF64 && !DumpOpts.IsEH ? 16 : 8,
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getCIEId(IsDWARF64, DumpOpts.IsEH))
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<< " CIE\n"
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<< " Format: " << FormatString(IsDWARF64) << "\n";
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if (DumpOpts.IsEH && Version != 1)
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OS << "WARNING: unsupported CIE version\n";
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OS << format(" Version: %d\n", Version)
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<< " Augmentation: \"" << Augmentation << "\"\n";
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if (Version >= 4) {
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OS << format(" Address size: %u\n", (uint32_t)AddressSize);
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OS << format(" Segment desc size: %u\n",
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(uint32_t)SegmentDescriptorSize);
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}
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OS << format(" Code alignment factor: %u\n", (uint32_t)CodeAlignmentFactor);
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OS << format(" Data alignment factor: %d\n", (int32_t)DataAlignmentFactor);
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OS << format(" Return address column: %d\n", (int32_t)ReturnAddressRegister);
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if (Personality)
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OS << format(" Personality Address: %016" PRIx64 "\n", *Personality);
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if (!AugmentationData.empty()) {
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OS << " Augmentation data: ";
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for (uint8_t Byte : AugmentationData)
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OS << ' ' << hexdigit(Byte >> 4) << hexdigit(Byte & 0xf);
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OS << "\n";
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}
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OS << "\n";
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printCFIProgram(CFIs, OS, DumpOpts, /*IndentLevel=*/1,
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/*InitialLocation=*/{});
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OS << "\n";
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if (Expected<UnwindTable> RowsOrErr = createUnwindTable(this))
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printUnwindTable(*RowsOrErr, OS, DumpOpts, 1);
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else {
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DumpOpts.RecoverableErrorHandler(joinErrors(
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createStringError(errc::invalid_argument,
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"decoding the CIE opcodes into rows failed"),
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RowsOrErr.takeError()));
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}
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OS << "\n";
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}
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void FDE::dump(raw_ostream &OS, DIDumpOptions DumpOpts) const {
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OS << format("%08" PRIx64, Offset)
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<< format(" %0*" PRIx64, IsDWARF64 ? 16 : 8, Length)
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<< format(" %0*" PRIx64, IsDWARF64 && !DumpOpts.IsEH ? 16 : 8, CIEPointer)
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<< " FDE cie=";
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if (LinkedCIE)
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OS << format("%08" PRIx64, LinkedCIE->getOffset());
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else
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OS << "<invalid offset>";
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OS << format(" pc=%08" PRIx64 "...%08" PRIx64 "\n", InitialLocation,
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InitialLocation + AddressRange);
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OS << " Format: " << FormatString(IsDWARF64) << "\n";
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if (LSDAAddress)
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OS << format(" LSDA Address: %016" PRIx64 "\n", *LSDAAddress);
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printCFIProgram(CFIs, OS, DumpOpts, /*IndentLevel=*/1, InitialLocation);
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OS << "\n";
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if (Expected<UnwindTable> RowsOrErr = createUnwindTable(this))
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printUnwindTable(*RowsOrErr, OS, DumpOpts, 1);
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else {
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DumpOpts.RecoverableErrorHandler(joinErrors(
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createStringError(errc::invalid_argument,
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"decoding the FDE opcodes into rows failed"),
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RowsOrErr.takeError()));
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}
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OS << "\n";
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}
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DWARFDebugFrame::DWARFDebugFrame(Triple::ArchType Arch,
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bool IsEH, uint64_t EHFrameAddress)
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: Arch(Arch), IsEH(IsEH), EHFrameAddress(EHFrameAddress) {}
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DWARFDebugFrame::~DWARFDebugFrame() = default;
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static void LLVM_ATTRIBUTE_UNUSED dumpDataAux(DataExtractor Data,
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uint64_t Offset, int Length) {
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errs() << "DUMP: ";
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for (int i = 0; i < Length; ++i) {
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uint8_t c = Data.getU8(&Offset);
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errs().write_hex(c); errs() << " ";
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}
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errs() << "\n";
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}
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Error DWARFDebugFrame::parse(DWARFDataExtractor Data) {
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uint64_t Offset = 0;
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DenseMap<uint64_t, CIE *> CIEs;
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while (Data.isValidOffset(Offset)) {
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uint64_t StartOffset = Offset;
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uint64_t Length;
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DwarfFormat Format;
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std::tie(Length, Format) = Data.getInitialLength(&Offset);
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bool IsDWARF64 = Format == DWARF64;
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// If the Length is 0, then this CIE is a terminator. We add it because some
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// dumper tools might need it to print something special for such entries
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// (e.g. llvm-objdump --dwarf=frames prints "ZERO terminator").
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if (Length == 0) {
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auto Cie = std::make_unique<CIE>(
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IsDWARF64, StartOffset, 0, 0, SmallString<8>(), 0, 0, 0, 0, 0,
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SmallString<8>(), 0, 0, std::nullopt, std::nullopt, Arch);
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CIEs[StartOffset] = Cie.get();
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Entries.push_back(std::move(Cie));
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break;
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}
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// At this point, Offset points to the next field after Length.
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// Length is the structure size excluding itself. Compute an offset one
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// past the end of the structure (needed to know how many instructions to
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// read).
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uint64_t StartStructureOffset = Offset;
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uint64_t EndStructureOffset = Offset + Length;
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// The Id field's size depends on the DWARF format
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Error Err = Error::success();
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uint64_t Id = Data.getRelocatedValue((IsDWARF64 && !IsEH) ? 8 : 4, &Offset,
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/*SectionIndex=*/nullptr, &Err);
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if (Err)
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return Err;
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if (Id == getCIEId(IsDWARF64, IsEH)) {
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uint8_t Version = Data.getU8(&Offset);
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const char *Augmentation = Data.getCStr(&Offset);
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StringRef AugmentationString(Augmentation ? Augmentation : "");
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uint8_t AddressSize = Version < 4 ? Data.getAddressSize() :
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Data.getU8(&Offset);
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Data.setAddressSize(AddressSize);
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uint8_t SegmentDescriptorSize = Version < 4 ? 0 : Data.getU8(&Offset);
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uint64_t CodeAlignmentFactor = Data.getULEB128(&Offset);
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int64_t DataAlignmentFactor = Data.getSLEB128(&Offset);
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uint64_t ReturnAddressRegister =
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Version == 1 ? Data.getU8(&Offset) : Data.getULEB128(&Offset);
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// Parse the augmentation data for EH CIEs
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StringRef AugmentationData("");
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uint32_t FDEPointerEncoding = DW_EH_PE_absptr;
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uint32_t LSDAPointerEncoding = DW_EH_PE_omit;
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std::optional<uint64_t> Personality;
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std::optional<uint32_t> PersonalityEncoding;
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if (IsEH) {
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std::optional<uint64_t> AugmentationLength;
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uint64_t StartAugmentationOffset;
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uint64_t EndAugmentationOffset;
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// Walk the augmentation string to get all the augmentation data.
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for (unsigned i = 0, e = AugmentationString.size(); i != e; ++i) {
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switch (AugmentationString[i]) {
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default:
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return createStringError(
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errc::invalid_argument,
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"unknown augmentation character %c in entry at 0x%" PRIx64,
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AugmentationString[i], StartOffset);
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case 'L':
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LSDAPointerEncoding = Data.getU8(&Offset);
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break;
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case 'P': {
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if (Personality)
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return createStringError(
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errc::invalid_argument,
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"duplicate personality in entry at 0x%" PRIx64, StartOffset);
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PersonalityEncoding = Data.getU8(&Offset);
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Personality = Data.getEncodedPointer(
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&Offset, *PersonalityEncoding,
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EHFrameAddress ? EHFrameAddress + Offset : 0);
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break;
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}
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case 'R':
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FDEPointerEncoding = Data.getU8(&Offset);
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break;
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case 'S':
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// Current frame is a signal trampoline.
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break;
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case 'z':
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if (i)
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return createStringError(
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errc::invalid_argument,
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"'z' must be the first character at 0x%" PRIx64, StartOffset);
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// Parse the augmentation length first. We only parse it if
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// the string contains a 'z'.
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AugmentationLength = Data.getULEB128(&Offset);
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StartAugmentationOffset = Offset;
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EndAugmentationOffset = Offset + *AugmentationLength;
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break;
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case 'B':
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// B-Key is used for signing functions associated with this
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// augmentation string
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break;
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// This stack frame contains MTE tagged data, so needs to be
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// untagged on unwind.
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case 'G':
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break;
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}
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}
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if (AugmentationLength) {
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if (Offset != EndAugmentationOffset)
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return createStringError(errc::invalid_argument,
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"parsing augmentation data at 0x%" PRIx64
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" failed",
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StartOffset);
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AugmentationData = Data.getData().slice(StartAugmentationOffset,
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EndAugmentationOffset);
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}
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}
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auto Cie = std::make_unique<CIE>(
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IsDWARF64, StartOffset, Length, Version, AugmentationString,
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AddressSize, SegmentDescriptorSize, CodeAlignmentFactor,
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DataAlignmentFactor, ReturnAddressRegister, AugmentationData,
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FDEPointerEncoding, LSDAPointerEncoding, Personality,
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PersonalityEncoding, Arch);
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CIEs[StartOffset] = Cie.get();
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Entries.emplace_back(std::move(Cie));
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} else {
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// FDE
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uint64_t CIEPointer = Id;
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uint64_t InitialLocation = 0;
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uint64_t AddressRange = 0;
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std::optional<uint64_t> LSDAAddress;
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CIE *Cie = CIEs[IsEH ? (StartStructureOffset - CIEPointer) : CIEPointer];
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if (IsEH) {
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// The address size is encoded in the CIE we reference.
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if (!Cie)
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return createStringError(errc::invalid_argument,
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"parsing FDE data at 0x%" PRIx64
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" failed due to missing CIE",
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StartOffset);
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if (auto Val =
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Data.getEncodedPointer(&Offset, Cie->getFDEPointerEncoding(),
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EHFrameAddress + Offset)) {
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InitialLocation = *Val;
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}
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if (auto Val = Data.getEncodedPointer(
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&Offset, Cie->getFDEPointerEncoding(), 0)) {
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AddressRange = *Val;
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}
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StringRef AugmentationString = Cie->getAugmentationString();
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if (!AugmentationString.empty()) {
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// Parse the augmentation length and data for this FDE.
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uint64_t AugmentationLength = Data.getULEB128(&Offset);
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uint64_t EndAugmentationOffset = Offset + AugmentationLength;
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// Decode the LSDA if the CIE augmentation string said we should.
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if (Cie->getLSDAPointerEncoding() != DW_EH_PE_omit) {
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LSDAAddress = Data.getEncodedPointer(
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&Offset, Cie->getLSDAPointerEncoding(),
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EHFrameAddress ? Offset + EHFrameAddress : 0);
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}
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if (Offset != EndAugmentationOffset)
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return createStringError(errc::invalid_argument,
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"parsing augmentation data at 0x%" PRIx64
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" failed",
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StartOffset);
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}
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} else {
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InitialLocation = Data.getRelocatedAddress(&Offset);
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AddressRange = Data.getRelocatedAddress(&Offset);
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}
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Entries.emplace_back(new FDE(IsDWARF64, StartOffset, Length, CIEPointer,
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InitialLocation, AddressRange, Cie,
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LSDAAddress, Arch));
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}
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if (Error E =
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Entries.back()->cfis().parse(Data, &Offset, EndStructureOffset))
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return E;
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if (Offset != EndStructureOffset)
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return createStringError(
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errc::invalid_argument,
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"parsing entry instructions at 0x%" PRIx64 " failed", StartOffset);
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}
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return Error::success();
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}
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FrameEntry *DWARFDebugFrame::getEntryAtOffset(uint64_t Offset) const {
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auto It = partition_point(Entries, [=](const std::unique_ptr<FrameEntry> &E) {
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return E->getOffset() < Offset;
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});
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if (It != Entries.end() && (*It)->getOffset() == Offset)
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return It->get();
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return nullptr;
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}
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void DWARFDebugFrame::dump(raw_ostream &OS, DIDumpOptions DumpOpts,
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std::optional<uint64_t> Offset) const {
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DumpOpts.IsEH = IsEH;
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if (Offset) {
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if (auto *Entry = getEntryAtOffset(*Offset))
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Entry->dump(OS, DumpOpts);
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return;
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}
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OS << "\n";
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for (const auto &Entry : Entries)
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Entry->dump(OS, DumpOpts);
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}
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