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llvm-project/llvm/tools/llvm-dwarfutil/DebugInfoLinker.cpp
Alexey Lapshin c965ffa1ed [llvm-dwarfutil][DWARFv5] fix reading of DW_FORM_addrx attribute. 
llvm::dwarfutil::ObjFileAddressMap::relocateIndexedAddr() does not
read address value. The relocateIndexedAddr() should not relocate
the address as the linked binary has already resolved relocations.
But it should read the value. This patch adds the reading value
of the address.

Differential Revision: https://reviews.llvm.org/D133324
2022-09-23 09:35:54 +03:00

350 lines
12 KiB
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//=== DebugInfoLinker.cpp -------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "DebugInfoLinker.h"
#include "Error.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/DWARFLinker/DWARFLinker.h"
#include "llvm/DWARFLinker/DWARFStreamer.h"
#include "llvm/DebugInfo/DWARF/DWARFContext.h"
#include "llvm/DebugInfo/DWARF/DWARFExpression.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/Endian.h"
#include <memory>
#include <vector>
namespace llvm {
namespace dwarfutil {
// ObjFileAddressMap allows to check whether specified DIE referencing
// dead addresses. It uses tombstone values to determine dead addresses.
// The concrete values of tombstone constants were discussed in
// https://reviews.llvm.org/D81784 and https://reviews.llvm.org/D84825.
// So we use following values as indicators of dead addresses:
//
// bfd: (LowPC == 0) or (LowPC == 1 and HighPC == 1 and DWARF v4 (or less))
// or ([LowPC, HighPC] is not inside address ranges of .text sections).
//
// maxpc: (LowPC == -1) or (LowPC == -2 and DWARF v4 (or less))
// That value is assumed to be compatible with
// http://www.dwarfstd.org/ShowIssue.php?issue=200609.1
//
// exec: [LowPC, HighPC] is not inside address ranges of .text sections
//
// universal: maxpc and bfd
class ObjFileAddressMap : public AddressesMap {
public:
ObjFileAddressMap(DWARFContext &Context, const Options &Options,
object::ObjectFile &ObjFile)
: Opts(Options), Context(Context) {
// Remember addresses of existing text sections.
for (const object::SectionRef &Sect : ObjFile.sections()) {
if (!Sect.isText())
continue;
const uint64_t Size = Sect.getSize();
if (Size == 0)
continue;
const uint64_t StartAddr = Sect.getAddress();
TextAddressRanges.insert({StartAddr, StartAddr + Size});
}
// Check CU address ranges for tombstone value.
for (std::unique_ptr<DWARFUnit> &CU : Context.compile_units()) {
Expected<llvm::DWARFAddressRangesVector> ARanges =
CU->getUnitDIE().getAddressRanges();
if (ARanges) {
for (auto &Range : *ARanges) {
if (!isDeadAddressRange(Range.LowPC, Range.HighPC, CU->getVersion(),
Options.Tombstone, CU->getAddressByteSize()))
DWARFAddressRanges.insert({Range.LowPC, Range.HighPC}, 0);
}
}
}
}
// should be renamed into has valid address ranges
bool hasValidRelocs() override { return !DWARFAddressRanges.empty(); }
bool isLiveSubprogram(const DWARFDie &DIE,
CompileUnit::DIEInfo &Info) override {
assert((DIE.getTag() == dwarf::DW_TAG_subprogram ||
DIE.getTag() == dwarf::DW_TAG_label) &&
"Wrong type of input die");
if (Optional<uint64_t> LowPC =
dwarf::toAddress(DIE.find(dwarf::DW_AT_low_pc))) {
if (!isDeadAddress(*LowPC, DIE.getDwarfUnit()->getVersion(),
Opts.Tombstone,
DIE.getDwarfUnit()->getAddressByteSize())) {
Info.AddrAdjust = 0;
Info.InDebugMap = true;
return true;
}
}
return false;
}
bool isLiveVariable(const DWARFDie &DIE,
CompileUnit::DIEInfo &Info) override {
assert((DIE.getTag() == dwarf::DW_TAG_variable ||
DIE.getTag() == dwarf::DW_TAG_constant) &&
"Wrong type of input die");
if (Expected<DWARFLocationExpressionsVector> Loc =
DIE.getLocations(dwarf::DW_AT_location)) {
DWARFUnit *U = DIE.getDwarfUnit();
for (const auto &Entry : *Loc) {
DataExtractor Data(toStringRef(Entry.Expr),
U->getContext().isLittleEndian(), 0);
DWARFExpression Expression(Data, U->getAddressByteSize(),
U->getFormParams().Format);
bool HasLiveAddresses =
any_of(Expression, [&](const DWARFExpression::Operation &Op) {
// TODO: add handling of dwarf::DW_OP_addrx
return !Op.isError() &&
(Op.getCode() == dwarf::DW_OP_addr &&
!isDeadAddress(Op.getRawOperand(0), U->getVersion(),
Opts.Tombstone,
DIE.getDwarfUnit()->getAddressByteSize()));
});
if (HasLiveAddresses) {
Info.AddrAdjust = 0;
Info.InDebugMap = true;
return true;
}
}
} else {
// FIXME: missing DW_AT_location is OK here, but other errors should be
// reported to the user.
consumeError(Loc.takeError());
}
return false;
}
bool applyValidRelocs(MutableArrayRef<char>, uint64_t, bool) override {
// no need to apply relocations to the linked binary.
return false;
}
RangesTy &getValidAddressRanges() override { return DWARFAddressRanges; };
void clear() override { DWARFAddressRanges.clear(); }
llvm::Expected<uint64_t> relocateIndexedAddr(uint64_t StartOffset,
uint64_t EndOffset) override {
// No relocations in linked binary. Return just address value.
const char *AddrPtr =
Context.getDWARFObj().getAddrSection().Data.data() + StartOffset;
support::endianness Endianess =
Context.getDWARFObj().isLittleEndian() ? support::little : support::big;
assert(EndOffset > StartOffset);
switch (EndOffset - StartOffset) {
case 1:
return *AddrPtr;
case 2:
return support::endian::read16(AddrPtr, Endianess);
case 4:
return support::endian::read32(AddrPtr, Endianess);
case 8:
return support::endian::read64(AddrPtr, Endianess);
}
llvm_unreachable("relocateIndexedAddr unhandled case!");
}
protected:
// returns true if specified address range is inside address ranges
// of executable sections.
bool isInsideExecutableSectionsAddressRange(uint64_t LowPC,
Optional<uint64_t> HighPC) {
Optional<AddressRange> Range =
TextAddressRanges.getRangeThatContains(LowPC);
if (HighPC)
return Range.has_value() && Range->end() >= *HighPC;
return Range.has_value();
}
uint64_t isBFDDeadAddressRange(uint64_t LowPC, Optional<uint64_t> HighPC,
uint16_t Version) {
if (LowPC == 0)
return true;
if ((Version <= 4) && HighPC && (LowPC == 1 && *HighPC == 1))
return true;
return !isInsideExecutableSectionsAddressRange(LowPC, HighPC);
}
uint64_t isMAXPCDeadAddressRange(uint64_t LowPC, Optional<uint64_t> HighPC,
uint16_t Version, uint8_t AddressByteSize) {
if (Version <= 4 && HighPC) {
if (LowPC == (dwarf::computeTombstoneAddress(AddressByteSize) - 1))
return true;
} else if (LowPC == dwarf::computeTombstoneAddress(AddressByteSize))
return true;
if (!isInsideExecutableSectionsAddressRange(LowPC, HighPC))
warning("Address referencing invalid text section is not marked with "
"tombstone value");
return false;
}
bool isDeadAddressRange(uint64_t LowPC, Optional<uint64_t> HighPC,
uint16_t Version, TombstoneKind Tombstone,
uint8_t AddressByteSize) {
switch (Tombstone) {
case TombstoneKind::BFD:
return isBFDDeadAddressRange(LowPC, HighPC, Version);
case TombstoneKind::MaxPC:
return isMAXPCDeadAddressRange(LowPC, HighPC, Version, AddressByteSize);
case TombstoneKind::Universal:
return isBFDDeadAddressRange(LowPC, HighPC, Version) ||
isMAXPCDeadAddressRange(LowPC, HighPC, Version, AddressByteSize);
case TombstoneKind::Exec:
return !isInsideExecutableSectionsAddressRange(LowPC, HighPC);
}
llvm_unreachable("Unknown tombstone value");
}
bool isDeadAddress(uint64_t LowPC, uint16_t Version, TombstoneKind Tombstone,
uint8_t AddressByteSize) {
return isDeadAddressRange(LowPC, None, Version, Tombstone, AddressByteSize);
}
private:
RangesTy DWARFAddressRanges;
AddressRanges TextAddressRanges;
const Options &Opts;
DWARFContext &Context;
};
static bool knownByDWARFUtil(StringRef SecName) {
return llvm::StringSwitch<bool>(SecName)
.Case(".debug_info", true)
.Case(".debug_types", true)
.Case(".debug_abbrev", true)
.Case(".debug_loc", true)
.Case(".debug_loclists", true)
.Case(".debug_frame", true)
.Case(".debug_aranges", true)
.Case(".debug_ranges", true)
.Case(".debug_rnglists", true)
.Case(".debug_line", true)
.Case(".debug_line_str", true)
.Case(".debug_addr", true)
.Case(".debug_macro", true)
.Case(".debug_macinfo", true)
.Case(".debug_str", true)
.Case(".debug_str_offsets", true)
.Default(false);
}
Error linkDebugInfo(object::ObjectFile &File, const Options &Options,
raw_pwrite_stream &OutStream) {
auto ReportWarn = [&](const Twine &Message, StringRef Context,
const DWARFDie *Die) {
warning(Message, Context);
if (!Options.Verbose || !Die)
return;
DIDumpOptions DumpOpts;
DumpOpts.ChildRecurseDepth = 0;
DumpOpts.Verbose = Options.Verbose;
WithColor::note() << " in DIE:\n";
Die->dump(errs(), /*Indent=*/6, DumpOpts);
};
auto ReportErr = [&](const Twine &Message, StringRef Context,
const DWARFDie *) {
WithColor::error(errs(), Context) << Message << '\n';
};
// Create output streamer.
DwarfStreamer OutStreamer(OutputFileType::Object, OutStream, nullptr,
ReportWarn, ReportWarn);
Triple TargetTriple = File.makeTriple();
if (!OutStreamer.init(TargetTriple, formatv("cannot create a stream for {0}",
TargetTriple.getTriple())
.str()))
return createStringError(std::errc::invalid_argument, "");
std::unique_ptr<DWARFContext> Context = DWARFContext::create(File);
uint16_t MaxDWARFVersion = 0;
std::function<void(const DWARFUnit &Unit)> OnCUDieLoaded =
[&MaxDWARFVersion](const DWARFUnit &Unit) {
MaxDWARFVersion = std::max(Unit.getVersion(), MaxDWARFVersion);
};
// Create DWARF linker.
DWARFLinker DebugInfoLinker(&OutStreamer, DwarfLinkerClient::LLD);
DebugInfoLinker.setEstimatedObjfilesAmount(1);
DebugInfoLinker.setAccelTableKind(DwarfLinkerAccelTableKind::None);
DebugInfoLinker.setErrorHandler(ReportErr);
DebugInfoLinker.setWarningHandler(ReportWarn);
DebugInfoLinker.setNumThreads(Options.NumThreads);
DebugInfoLinker.setNoODR(!Options.DoODRDeduplication);
DebugInfoLinker.setVerbosity(Options.Verbose);
DebugInfoLinker.setUpdate(!Options.DoGarbageCollection);
std::vector<std::unique_ptr<DWARFFile>> ObjectsForLinking(1);
std::vector<std::unique_ptr<AddressesMap>> AddresssMapForLinking(1);
std::vector<std::string> EmptyWarnings;
// Unknown debug sections would be removed. Display warning
// for such sections.
for (SectionName Sec : Context->getDWARFObj().getSectionNames()) {
if (isDebugSection(Sec.Name) && !knownByDWARFUtil(Sec.Name))
warning(
formatv("'{0}' is not currently supported: section will be skipped",
Sec.Name),
Options.InputFileName);
}
// Add object files to the DWARFLinker.
AddresssMapForLinking[0] =
std::make_unique<ObjFileAddressMap>(*Context, Options, File);
ObjectsForLinking[0] = std::make_unique<DWARFFile>(
File.getFileName(), &*Context, AddresssMapForLinking[0].get(),
EmptyWarnings);
for (size_t I = 0; I < ObjectsForLinking.size(); I++)
DebugInfoLinker.addObjectFile(*ObjectsForLinking[I], nullptr,
OnCUDieLoaded);
// If we haven't seen any CUs, pick an arbitrary valid Dwarf version anyway.
if (MaxDWARFVersion == 0)
MaxDWARFVersion = 3;
if (Error Err = DebugInfoLinker.setTargetDWARFVersion(MaxDWARFVersion))
return Err;
// Link debug info.
if (Error Err = DebugInfoLinker.link())
return Err;
OutStreamer.finish();
return Error::success();
}
} // end of namespace dwarfutil
} // end of namespace llvm
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