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llvm-mirror/tools/dsymutil/MachODebugMapParser.cpp
Jonas Devlieghere 4b2f074364 [dsymutil] Generalize handling of aliases external symbols 
In f9fb9da36c34d2745b74dc30e6c26f7d3f48466c we fixed spurious warnings
caused by aliases to private extern symbols. This patch generalizes that
to regular external symbols as well.
2020-11-16 11:04:31 -08:00

608 lines
21 KiB
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//===- tools/dsymutil/MachODebugMapParser.cpp - Parse STABS debug maps ----===//
//
// 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 "BinaryHolder.h"
#include "DebugMap.h"
#include "MachOUtils.h"
#include "llvm/ADT/Optional.h"
#include "llvm/Object/MachO.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/WithColor.h"
#include "llvm/Support/raw_ostream.h"
#include <vector>
namespace {
using namespace llvm;
using namespace llvm::dsymutil;
using namespace llvm::object;
class MachODebugMapParser {
public:
MachODebugMapParser(llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
StringRef BinaryPath, ArrayRef<std::string> Archs,
StringRef PathPrefix = "",
bool PaperTrailWarnings = false, bool Verbose = false)
: BinaryPath(std::string(BinaryPath)), Archs(Archs.begin(), Archs.end()),
PathPrefix(std::string(PathPrefix)),
PaperTrailWarnings(PaperTrailWarnings), BinHolder(VFS, Verbose),
CurrentDebugMapObject(nullptr) {}
/// Parses and returns the DebugMaps of the input binary. The binary contains
/// multiple maps in case it is a universal binary.
/// \returns an error in case the provided BinaryPath doesn't exist
/// or isn't of a supported type.
ErrorOr<std::vector<std::unique_ptr<DebugMap>>> parse();
/// Walk the symbol table and dump it.
bool dumpStab();
private:
std::string BinaryPath;
SmallVector<StringRef, 1> Archs;
std::string PathPrefix;
bool PaperTrailWarnings;
/// Owns the MemoryBuffer for the main binary.
BinaryHolder BinHolder;
/// Map of the binary symbol addresses.
StringMap<uint64_t> MainBinarySymbolAddresses;
StringRef MainBinaryStrings;
/// The constructed DebugMap.
std::unique_ptr<DebugMap> Result;
/// List of common symbols that need to be added to the debug map.
std::vector<std::string> CommonSymbols;
/// Map of the currently processed object file symbol addresses.
StringMap<Optional<uint64_t>> CurrentObjectAddresses;
/// Element of the debug map corresponding to the current object file.
DebugMapObject *CurrentDebugMapObject;
/// Holds function info while function scope processing.
const char *CurrentFunctionName;
uint64_t CurrentFunctionAddress;
std::unique_ptr<DebugMap> parseOneBinary(const MachOObjectFile &MainBinary,
StringRef BinaryPath);
void
switchToNewDebugMapObject(StringRef Filename,
sys::TimePoint<std::chrono::seconds> Timestamp);
void resetParserState();
uint64_t getMainBinarySymbolAddress(StringRef Name);
std::vector<StringRef> getMainBinarySymbolNames(uint64_t Value);
void loadMainBinarySymbols(const MachOObjectFile &MainBinary);
void loadCurrentObjectFileSymbols(const object::MachOObjectFile &Obj);
void handleStabSymbolTableEntry(uint32_t StringIndex, uint8_t Type,
uint8_t SectionIndex, uint16_t Flags,
uint64_t Value);
template <typename STEType> void handleStabDebugMapEntry(const STEType &STE) {
handleStabSymbolTableEntry(STE.n_strx, STE.n_type, STE.n_sect, STE.n_desc,
STE.n_value);
}
void addCommonSymbols();
/// Dump the symbol table output header.
void dumpSymTabHeader(raw_ostream &OS, StringRef Arch);
/// Dump the contents of nlist entries.
void dumpSymTabEntry(raw_ostream &OS, uint64_t Index, uint32_t StringIndex,
uint8_t Type, uint8_t SectionIndex, uint16_t Flags,
uint64_t Value);
template <typename STEType>
void dumpSymTabEntry(raw_ostream &OS, uint64_t Index, const STEType &STE) {
dumpSymTabEntry(OS, Index, STE.n_strx, STE.n_type, STE.n_sect, STE.n_desc,
STE.n_value);
}
void dumpOneBinaryStab(const MachOObjectFile &MainBinary,
StringRef BinaryPath);
void Warning(const Twine &Msg, StringRef File = StringRef()) {
WithColor::warning() << "("
<< MachOUtils::getArchName(
Result->getTriple().getArchName())
<< ") " << File << " " << Msg << "\n";
if (PaperTrailWarnings) {
if (!File.empty())
Result->addDebugMapObject(File, sys::TimePoint<std::chrono::seconds>());
if (Result->end() != Result->begin())
(*--Result->end())->addWarning(Msg.str());
}
}
};
} // anonymous namespace
/// Reset the parser state corresponding to the current object
/// file. This is to be called after an object file is finished
/// processing.
void MachODebugMapParser::resetParserState() {
CommonSymbols.clear();
CurrentObjectAddresses.clear();
CurrentDebugMapObject = nullptr;
}
/// Commons symbols won't show up in the symbol map but might need to be
/// relocated. We can add them to the symbol table ourselves by combining the
/// information in the object file (the symbol name) and the main binary (the
/// address).
void MachODebugMapParser::addCommonSymbols() {
for (auto &CommonSymbol : CommonSymbols) {
uint64_t CommonAddr = getMainBinarySymbolAddress(CommonSymbol);
if (CommonAddr == 0) {
// The main binary doesn't have an address for the given symbol.
continue;
}
if (!CurrentDebugMapObject->addSymbol(CommonSymbol, None /*ObjectAddress*/,
CommonAddr, 0 /*size*/)) {
// The symbol is already present.
continue;
}
}
}
/// Create a new DebugMapObject. This function resets the state of the
/// parser that was referring to the last object file and sets
/// everything up to add symbols to the new one.
void MachODebugMapParser::switchToNewDebugMapObject(
StringRef Filename, sys::TimePoint<std::chrono::seconds> Timestamp) {
addCommonSymbols();
resetParserState();
SmallString<80> Path(PathPrefix);
sys::path::append(Path, Filename);
auto ObjectEntry = BinHolder.getObjectEntry(Path, Timestamp);
if (!ObjectEntry) {
auto Err = ObjectEntry.takeError();
Warning("unable to open object file: " + toString(std::move(Err)),
Path.str());
return;
}
auto Object = ObjectEntry->getObjectAs<MachOObjectFile>(Result->getTriple());
if (!Object) {
auto Err = Object.takeError();
Warning("unable to open object file: " + toString(std::move(Err)),
Path.str());
return;
}
CurrentDebugMapObject =
&Result->addDebugMapObject(Path, Timestamp, MachO::N_OSO);
loadCurrentObjectFileSymbols(*Object);
}
static std::string getArchName(const object::MachOObjectFile &Obj) {
Triple T = Obj.getArchTriple();
return std::string(T.getArchName());
}
std::unique_ptr<DebugMap>
MachODebugMapParser::parseOneBinary(const MachOObjectFile &MainBinary,
StringRef BinaryPath) {
loadMainBinarySymbols(MainBinary);
ArrayRef<uint8_t> UUID = MainBinary.getUuid();
Result =
std::make_unique<DebugMap>(MainBinary.getArchTriple(), BinaryPath, UUID);
MainBinaryStrings = MainBinary.getStringTableData();
for (const SymbolRef &Symbol : MainBinary.symbols()) {
const DataRefImpl &DRI = Symbol.getRawDataRefImpl();
if (MainBinary.is64Bit())
handleStabDebugMapEntry(MainBinary.getSymbol64TableEntry(DRI));
else
handleStabDebugMapEntry(MainBinary.getSymbolTableEntry(DRI));
}
resetParserState();
return std::move(Result);
}
// Table that maps Darwin's Mach-O stab constants to strings to allow printing.
// llvm-nm has very similar code, the strings used here are however slightly
// different and part of the interface of dsymutil (some project's build-systems
// parse the ouptut of dsymutil -s), thus they shouldn't be changed.
struct DarwinStabName {
uint8_t NType;
const char *Name;
};
static const struct DarwinStabName DarwinStabNames[] = {
{MachO::N_GSYM, "N_GSYM"}, {MachO::N_FNAME, "N_FNAME"},
{MachO::N_FUN, "N_FUN"}, {MachO::N_STSYM, "N_STSYM"},
{MachO::N_LCSYM, "N_LCSYM"}, {MachO::N_BNSYM, "N_BNSYM"},
{MachO::N_PC, "N_PC"}, {MachO::N_AST, "N_AST"},
{MachO::N_OPT, "N_OPT"}, {MachO::N_RSYM, "N_RSYM"},
{MachO::N_SLINE, "N_SLINE"}, {MachO::N_ENSYM, "N_ENSYM"},
{MachO::N_SSYM, "N_SSYM"}, {MachO::N_SO, "N_SO"},
{MachO::N_OSO, "N_OSO"}, {MachO::N_LSYM, "N_LSYM"},
{MachO::N_BINCL, "N_BINCL"}, {MachO::N_SOL, "N_SOL"},
{MachO::N_PARAMS, "N_PARAM"}, {MachO::N_VERSION, "N_VERS"},
{MachO::N_OLEVEL, "N_OLEV"}, {MachO::N_PSYM, "N_PSYM"},
{MachO::N_EINCL, "N_EINCL"}, {MachO::N_ENTRY, "N_ENTRY"},
{MachO::N_LBRAC, "N_LBRAC"}, {MachO::N_EXCL, "N_EXCL"},
{MachO::N_RBRAC, "N_RBRAC"}, {MachO::N_BCOMM, "N_BCOMM"},
{MachO::N_ECOMM, "N_ECOMM"}, {MachO::N_ECOML, "N_ECOML"},
{MachO::N_LENG, "N_LENG"}, {0, nullptr}};
static const char *getDarwinStabString(uint8_t NType) {
for (unsigned i = 0; DarwinStabNames[i].Name; i++) {
if (DarwinStabNames[i].NType == NType)
return DarwinStabNames[i].Name;
}
return nullptr;
}
void MachODebugMapParser::dumpSymTabHeader(raw_ostream &OS, StringRef Arch) {
OS << "-----------------------------------"
"-----------------------------------\n";
OS << "Symbol table for: '" << BinaryPath << "' (" << Arch.data() << ")\n";
OS << "-----------------------------------"
"-----------------------------------\n";
OS << "Index n_strx n_type n_sect n_desc n_value\n";
OS << "======== -------- ------------------ ------ ------ ----------------\n";
}
void MachODebugMapParser::dumpSymTabEntry(raw_ostream &OS, uint64_t Index,
uint32_t StringIndex, uint8_t Type,
uint8_t SectionIndex, uint16_t Flags,
uint64_t Value) {
// Index
OS << '[' << format_decimal(Index, 6)
<< "] "
// n_strx
<< format_hex_no_prefix(StringIndex, 8)
<< ' '
// n_type...
<< format_hex_no_prefix(Type, 2) << " (";
if (Type & MachO::N_STAB)
OS << left_justify(getDarwinStabString(Type), 13);
else {
if (Type & MachO::N_PEXT)
OS << "PEXT ";
else
OS << " ";
switch (Type & MachO::N_TYPE) {
case MachO::N_UNDF: // 0x0 undefined, n_sect == NO_SECT
OS << "UNDF";
break;
case MachO::N_ABS: // 0x2 absolute, n_sect == NO_SECT
OS << "ABS ";
break;
case MachO::N_SECT: // 0xe defined in section number n_sect
OS << "SECT";
break;
case MachO::N_PBUD: // 0xc prebound undefined (defined in a dylib)
OS << "PBUD";
break;
case MachO::N_INDR: // 0xa indirect
OS << "INDR";
break;
default:
OS << format_hex_no_prefix(Type, 2) << " ";
break;
}
if (Type & MachO::N_EXT)
OS << " EXT";
else
OS << " ";
}
OS << ") "
// n_sect
<< format_hex_no_prefix(SectionIndex, 2)
<< " "
// n_desc
<< format_hex_no_prefix(Flags, 4)
<< " "
// n_value
<< format_hex_no_prefix(Value, 16);
const char *Name = &MainBinaryStrings.data()[StringIndex];
if (Name && Name[0])
OS << " '" << Name << "'";
OS << "\n";
}
void MachODebugMapParser::dumpOneBinaryStab(const MachOObjectFile &MainBinary,
StringRef BinaryPath) {
loadMainBinarySymbols(MainBinary);
MainBinaryStrings = MainBinary.getStringTableData();
raw_ostream &OS(llvm::outs());
dumpSymTabHeader(OS, getArchName(MainBinary));
uint64_t Idx = 0;
for (const SymbolRef &Symbol : MainBinary.symbols()) {
const DataRefImpl &DRI = Symbol.getRawDataRefImpl();
if (MainBinary.is64Bit())
dumpSymTabEntry(OS, Idx, MainBinary.getSymbol64TableEntry(DRI));
else
dumpSymTabEntry(OS, Idx, MainBinary.getSymbolTableEntry(DRI));
Idx++;
}
OS << "\n\n";
resetParserState();
}
static bool shouldLinkArch(SmallVectorImpl<StringRef> &Archs, StringRef Arch) {
if (Archs.empty() || is_contained(Archs, "all") || is_contained(Archs, "*"))
return true;
if (Arch.startswith("arm") && Arch != "arm64" && is_contained(Archs, "arm"))
return true;
SmallString<16> ArchName = Arch;
if (Arch.startswith("thumb"))
ArchName = ("arm" + Arch.substr(5)).str();
return is_contained(Archs, ArchName);
}
bool MachODebugMapParser::dumpStab() {
auto ObjectEntry = BinHolder.getObjectEntry(BinaryPath);
if (!ObjectEntry) {
auto Err = ObjectEntry.takeError();
WithColor::error() << "cannot load '" << BinaryPath
<< "': " << toString(std::move(Err)) << '\n';
return false;
}
auto Objects = ObjectEntry->getObjectsAs<MachOObjectFile>();
if (!Objects) {
auto Err = Objects.takeError();
WithColor::error() << "cannot get '" << BinaryPath
<< "' as MachO file: " << toString(std::move(Err))
<< "\n";
return false;
}
for (const auto *Object : *Objects)
if (shouldLinkArch(Archs, Object->getArchTriple().getArchName()))
dumpOneBinaryStab(*Object, BinaryPath);
return true;
}
/// This main parsing routine tries to open the main binary and if
/// successful iterates over the STAB entries. The real parsing is
/// done in handleStabSymbolTableEntry.
ErrorOr<std::vector<std::unique_ptr<DebugMap>>> MachODebugMapParser::parse() {
auto ObjectEntry = BinHolder.getObjectEntry(BinaryPath);
if (!ObjectEntry) {
return errorToErrorCode(ObjectEntry.takeError());
}
auto Objects = ObjectEntry->getObjectsAs<MachOObjectFile>();
if (!Objects) {
return errorToErrorCode(Objects.takeError());
}
std::vector<std::unique_ptr<DebugMap>> Results;
for (const auto *Object : *Objects)
if (shouldLinkArch(Archs, Object->getArchTriple().getArchName()))
Results.push_back(parseOneBinary(*Object, BinaryPath));
return std::move(Results);
}
/// Interpret the STAB entries to fill the DebugMap.
void MachODebugMapParser::handleStabSymbolTableEntry(uint32_t StringIndex,
uint8_t Type,
uint8_t SectionIndex,
uint16_t Flags,
uint64_t Value) {
if (!(Type & MachO::N_STAB))
return;
const char *Name = &MainBinaryStrings.data()[StringIndex];
// An N_OSO entry represents the start of a new object file description.
if (Type == MachO::N_OSO)
return switchToNewDebugMapObject(Name, sys::toTimePoint(Value));
if (Type == MachO::N_AST) {
SmallString<80> Path(PathPrefix);
sys::path::append(Path, Name);
Result->addDebugMapObject(Path, sys::toTimePoint(Value), Type);
return;
}
// If the last N_OSO object file wasn't found, CurrentDebugMapObject will be
// null. Do not update anything until we find the next valid N_OSO entry.
if (!CurrentDebugMapObject)
return;
uint32_t Size = 0;
switch (Type) {
case MachO::N_GSYM:
// This is a global variable. We need to query the main binary
// symbol table to find its address as it might not be in the
// debug map (for common symbols).
Value = getMainBinarySymbolAddress(Name);
break;
case MachO::N_FUN:
// Functions are scopes in STABS. They have an end marker that
// contains the function size.
if (Name[0] == '\0') {
Size = Value;
Value = CurrentFunctionAddress;
Name = CurrentFunctionName;
break;
} else {
CurrentFunctionName = Name;
CurrentFunctionAddress = Value;
return;
}
case MachO::N_STSYM:
break;
default:
return;
}
auto ObjectSymIt = CurrentObjectAddresses.find(Name);
// If the name of a (non-static) symbol is not in the current object, we
// check all its aliases from the main binary.
if (ObjectSymIt == CurrentObjectAddresses.end() && Type != MachO::N_STSYM) {
for (const auto &Alias : getMainBinarySymbolNames(Value)) {
ObjectSymIt = CurrentObjectAddresses.find(Alias);
if (ObjectSymIt != CurrentObjectAddresses.end())
break;
}
}
if (ObjectSymIt == CurrentObjectAddresses.end()) {
Warning("could not find object file symbol for symbol " + Twine(Name));
return;
}
if (!CurrentDebugMapObject->addSymbol(Name, ObjectSymIt->getValue(), Value,
Size)) {
Warning(Twine("failed to insert symbol '") + Name + "' in the debug map.");
return;
}
}
/// Load the current object file symbols into CurrentObjectAddresses.
void MachODebugMapParser::loadCurrentObjectFileSymbols(
const object::MachOObjectFile &Obj) {
CurrentObjectAddresses.clear();
for (auto Sym : Obj.symbols()) {
uint64_t Addr = cantFail(Sym.getValue());
Expected<StringRef> Name = Sym.getName();
if (!Name) {
// TODO: Actually report errors helpfully.
consumeError(Name.takeError());
continue;
}
// The value of some categories of symbols isn't meaningful. For
// example common symbols store their size in the value field, not
// their address. Absolute symbols have a fixed address that can
// conflict with standard symbols. These symbols (especially the
// common ones), might still be referenced by relocations. These
// relocations will use the symbol itself, and won't need an
// object file address. The object file address field is optional
// in the DebugMap, leave it unassigned for these symbols.
uint32_t Flags = cantFail(Sym.getFlags());
if (Flags & SymbolRef::SF_Absolute) {
CurrentObjectAddresses[*Name] = None;
} else if (Flags & SymbolRef::SF_Common) {
CurrentObjectAddresses[*Name] = None;
CommonSymbols.push_back(std::string(*Name));
} else {
CurrentObjectAddresses[*Name] = Addr;
}
}
}
/// Lookup a symbol address in the main binary symbol table. The
/// parser only needs to query common symbols, thus not every symbol's
/// address is available through this function.
uint64_t MachODebugMapParser::getMainBinarySymbolAddress(StringRef Name) {
auto Sym = MainBinarySymbolAddresses.find(Name);
if (Sym == MainBinarySymbolAddresses.end())
return 0;
return Sym->second;
}
/// Get all symbol names in the main binary for the given value.
std::vector<StringRef>
MachODebugMapParser::getMainBinarySymbolNames(uint64_t Value) {
std::vector<StringRef> Names;
for (const auto &Entry : MainBinarySymbolAddresses) {
if (Entry.second == Value)
Names.push_back(Entry.first());
}
return Names;
}
/// Load the interesting main binary symbols' addresses into
/// MainBinarySymbolAddresses.
void MachODebugMapParser::loadMainBinarySymbols(
const MachOObjectFile &MainBinary) {
section_iterator Section = MainBinary.section_end();
MainBinarySymbolAddresses.clear();
for (const auto &Sym : MainBinary.symbols()) {
Expected<SymbolRef::Type> TypeOrErr = Sym.getType();
if (!TypeOrErr) {
// TODO: Actually report errors helpfully.
consumeError(TypeOrErr.takeError());
continue;
}
SymbolRef::Type Type = *TypeOrErr;
// Skip undefined and STAB entries.
if ((Type == SymbolRef::ST_Debug) || (Type == SymbolRef::ST_Unknown))
continue;
// In theory, the only symbols of interest are the global variables. These
// are the only ones that need to be queried because the address of common
// data won't be described in the debug map. All other addresses should be
// fetched for the debug map. In reality, by playing with 'ld -r' and
// export lists, you can get symbols described as N_GSYM in the debug map,
// but associated with a local symbol. Gather all the symbols, but prefer
// the global ones.
uint8_t SymType =
MainBinary.getSymbolTableEntry(Sym.getRawDataRefImpl()).n_type;
bool Extern = SymType & (MachO::N_EXT | MachO::N_PEXT);
Expected<section_iterator> SectionOrErr = Sym.getSection();
if (!SectionOrErr) {
// TODO: Actually report errors helpfully.
consumeError(SectionOrErr.takeError());
continue;
}
Section = *SectionOrErr;
if ((Section == MainBinary.section_end() || Section->isText()) && !Extern)
continue;
uint64_t Addr = cantFail(Sym.getValue());
Expected<StringRef> NameOrErr = Sym.getName();
if (!NameOrErr) {
// TODO: Actually report errors helpfully.
consumeError(NameOrErr.takeError());
continue;
}
StringRef Name = *NameOrErr;
if (Name.size() == 0 || Name[0] == '\0')
continue;
// Override only if the new key is global.
if (Extern)
MainBinarySymbolAddresses[Name] = Addr;
else
MainBinarySymbolAddresses.try_emplace(Name, Addr);
}
}
namespace llvm {
namespace dsymutil {
llvm::ErrorOr<std::vector<std::unique_ptr<DebugMap>>>
parseDebugMap(llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
StringRef InputFile, ArrayRef<std::string> Archs,
StringRef PrependPath, bool PaperTrailWarnings, bool Verbose,
bool InputIsYAML) {
if (InputIsYAML)
return DebugMap::parseYAMLDebugMap(InputFile, PrependPath, Verbose);
MachODebugMapParser Parser(VFS, InputFile, Archs, PrependPath,
PaperTrailWarnings, Verbose);
return Parser.parse();
}
bool dumpStab(llvm::IntrusiveRefCntPtr<llvm::vfs::FileSystem> VFS,
StringRef InputFile, ArrayRef<std::string> Archs,
StringRef PrependPath) {
MachODebugMapParser Parser(VFS, InputFile, Archs, PrependPath, false);
return Parser.dumpStab();
}
} // namespace dsymutil
} // namespace llvm
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