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llvm-project/llvm/lib/XRay/InstrumentationMap.cpp

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//===- InstrumentationMap.cpp - XRay Instrumentation Map ------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Implementation of the InstrumentationMap type for XRay sleds.
//
//===----------------------------------------------------------------------===//
#include "llvm/XRay/InstrumentationMap.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Triple.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Object/Binary.h"
#include "llvm/Object/ELFObjectFile.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Object/RelocationResolver.h"
#include "llvm/Support/DataExtractor.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/YAMLTraits.h"
#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <system_error>
#include <vector>
using namespace llvm;
using namespace xray;
Optional<int32_t> InstrumentationMap::getFunctionId(uint64_t Addr) const {
auto I = FunctionIds.find(Addr);
if (I != FunctionIds.end())
return I->second;
return None;
}
Optional<uint64_t> InstrumentationMap::getFunctionAddr(int32_t FuncId) const {
auto I = FunctionAddresses.find(FuncId);
if (I != FunctionAddresses.end())
return I->second;
return None;
}
using RelocMap = DenseMap<uint64_t, uint64_t>;
static Error
loadObj(StringRef Filename, object::OwningBinary<object::ObjectFile> &ObjFile,
InstrumentationMap::SledContainer &Sleds,
InstrumentationMap::FunctionAddressMap &FunctionAddresses,
InstrumentationMap::FunctionAddressReverseMap &FunctionIds) {
InstrumentationMap Map;
// Find the section named "xray_instr_map".
if ((!ObjFile.getBinary()->isELF() && !ObjFile.getBinary()->isMachO()) ||
!(ObjFile.getBinary()->getArch() == Triple::x86_64 ||
ObjFile.getBinary()->getArch() == Triple::ppc64le ||
ObjFile.getBinary()->getArch() == Triple::arm ||
ObjFile.getBinary()->getArch() == Triple::aarch64))
return make_error<StringError>(
"File format not supported (only does ELF and Mach-O little endian "
"64-bit).",
std::make_error_code(std::errc::not_supported));
StringRef Contents = "";
const auto &Sections = ObjFile.getBinary()->sections();
uint64_t Address = 0;
auto I = llvm::find_if(Sections, [&](object::SectionRef Section) {
Expected<StringRef> NameOrErr = Section.getName();
if (NameOrErr) {
Address = Section.getAddress();
return *NameOrErr == "xray_instr_map";
}
consumeError(NameOrErr.takeError());
return false;
});
if (I == Sections.end())
return make_error<StringError>(
"Failed to find XRay instrumentation map.",
std::make_error_code(std::errc::executable_format_error));
if (Expected<StringRef> E = I->getContents())
Contents = *E;
else
return E.takeError();
RelocMap Relocs;
if (ObjFile.getBinary()->isELF()) {
uint32_t RelativeRelocation = [](object::ObjectFile *ObjFile) {
if (const auto *ELFObj = dyn_cast<object::ELF32LEObjectFile>(ObjFile))
return ELFObj->getELFFile().getRelativeRelocationType();
else if (const auto *ELFObj =
dyn_cast<object::ELF32BEObjectFile>(ObjFile))
return ELFObj->getELFFile().getRelativeRelocationType();
else if (const auto *ELFObj =
dyn_cast<object::ELF64LEObjectFile>(ObjFile))
return ELFObj->getELFFile().getRelativeRelocationType();
else if (const auto *ELFObj =
dyn_cast<object::ELF64BEObjectFile>(ObjFile))
return ELFObj->getELFFile().getRelativeRelocationType();
else
return static_cast<uint32_t>(0);
}(ObjFile.getBinary());
object::SupportsRelocation Supports;
object::RelocationResolver Resolver;
std::tie(Supports, Resolver) =
object::getRelocationResolver(*ObjFile.getBinary());
for (const object::SectionRef &Section : Sections) {
for (const object::RelocationRef &Reloc : Section.relocations()) {
if (ObjFile.getBinary()->getArch() == Triple::arm) {
if (Supports && Supports(Reloc.getType())) {
Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue();
if (!ValueOrErr)
return ValueOrErr.takeError();
Relocs.insert(
{Reloc.getOffset(),
object::resolveRelocation(Resolver, Reloc, *ValueOrErr, 0)});
}
} else if (Supports && Supports(Reloc.getType())) {
auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend();
auto A = AddendOrErr ? *AddendOrErr : 0;
Expected<uint64_t> ValueOrErr = Reloc.getSymbol()->getValue();
if (!ValueOrErr)
// TODO: Test this error.
return ValueOrErr.takeError();
Relocs.insert(
{Reloc.getOffset(),
object::resolveRelocation(Resolver, Reloc, *ValueOrErr, A)});
} else if (Reloc.getType() == RelativeRelocation) {
if (auto AddendOrErr = object::ELFRelocationRef(Reloc).getAddend())
Relocs.insert({Reloc.getOffset(), *AddendOrErr});
}
}
}
}
// Copy the instrumentation map data into the Sleds data structure.
auto C = Contents.bytes_begin();
bool Is32Bit = ObjFile.getBinary()->makeTriple().isArch32Bit();
size_t ELFSledEntrySize = Is32Bit ? 16 : 32;
if ((C - Contents.bytes_end()) % ELFSledEntrySize != 0)
return make_error<StringError>(
Twine("Instrumentation map entries not evenly divisible by size of "
"an XRay sled entry."),
std::make_error_code(std::errc::executable_format_error));
auto RelocateOrElse = [&](uint64_t Offset, uint64_t Address) {
if (!Address) {
uint64_t A = I->getAddress() + C - Contents.bytes_begin() + Offset;
RelocMap::const_iterator R = Relocs.find(A);
if (R != Relocs.end())
return R->second;
}
return Address;
};
const int WordSize = Is32Bit ? 4 : 8;
int32_t FuncId = 1;
uint64_t CurFn = 0;
for (; C != Contents.bytes_end(); C += ELFSledEntrySize) {
DataExtractor Extractor(
StringRef(reinterpret_cast<const char *>(C), ELFSledEntrySize), true,
8);
Sleds.push_back({});
auto &Entry = Sleds.back();
uint64_t OffsetPtr = 0;
uint64_t AddrOff = OffsetPtr;
if (Is32Bit)
Entry.Address = RelocateOrElse(AddrOff, Extractor.getU32(&OffsetPtr));
else
Entry.Address = RelocateOrElse(AddrOff, Extractor.getU64(&OffsetPtr));
uint64_t FuncOff = OffsetPtr;
if (Is32Bit)
Entry.Function = RelocateOrElse(FuncOff, Extractor.getU32(&OffsetPtr));
else
Entry.Function = RelocateOrElse(FuncOff, Extractor.getU64(&OffsetPtr));
auto Kind = Extractor.getU8(&OffsetPtr);
static constexpr SledEntry::FunctionKinds Kinds[] = {
SledEntry::FunctionKinds::ENTRY, SledEntry::FunctionKinds::EXIT,
SledEntry::FunctionKinds::TAIL,
SledEntry::FunctionKinds::LOG_ARGS_ENTER,
SledEntry::FunctionKinds::CUSTOM_EVENT};
if (Kind >= sizeof(Kinds))
return errorCodeToError(
std::make_error_code(std::errc::executable_format_error));
Entry.Kind = Kinds[Kind];
Entry.AlwaysInstrument = Extractor.getU8(&OffsetPtr) != 0;
Entry.Version = Extractor.getU8(&OffsetPtr);
if (Entry.Version >= 2) {
Entry.Address += C - Contents.bytes_begin() + Address;
Entry.Function += C - Contents.bytes_begin() + WordSize + Address;
}
// We do replicate the function id generation scheme implemented in the
// XRay runtime.
// FIXME: Figure out how to keep this consistent with the XRay runtime.
if (CurFn == 0) {
CurFn = Entry.Function;
FunctionAddresses[FuncId] = Entry.Function;
FunctionIds[Entry.Function] = FuncId;
}
if (Entry.Function != CurFn) {
++FuncId;
CurFn = Entry.Function;
FunctionAddresses[FuncId] = Entry.Function;
FunctionIds[Entry.Function] = FuncId;
}
}
return Error::success();
}
static Error
loadYAML(sys::fs::file_t Fd, size_t FileSize, StringRef Filename,
InstrumentationMap::SledContainer &Sleds,
InstrumentationMap::FunctionAddressMap &FunctionAddresses,
InstrumentationMap::FunctionAddressReverseMap &FunctionIds) {
std::error_code EC;
sys::fs::mapped_file_region MappedFile(
Fd, sys::fs::mapped_file_region::mapmode::readonly, FileSize, 0, EC);
sys::fs::closeFile(Fd);
if (EC)
return make_error<StringError>(
Twine("Failed memory-mapping file '") + Filename + "'.", EC);
std::vector<YAMLXRaySledEntry> YAMLSleds;
yaml::Input In(StringRef(MappedFile.data(), MappedFile.size()));
In >> YAMLSleds;
if (In.error())
return make_error<StringError>(
Twine("Failed loading YAML document from '") + Filename + "'.",
In.error());
Sleds.reserve(YAMLSleds.size());
for (const auto &Y : YAMLSleds) {
FunctionAddresses[Y.FuncId] = Y.Function;
FunctionIds[Y.Function] = Y.FuncId;
Sleds.push_back(SledEntry{Y.Address, Y.Function, Y.Kind, Y.AlwaysInstrument,
Y.Version});
}
return Error::success();
}
// FIXME: Create error types that encapsulate a bit more information than what
// StringError instances contain.
Expected<InstrumentationMap>
llvm::xray::loadInstrumentationMap(StringRef Filename) {
// At this point we assume the file is an object file -- and if that doesn't
// work, we treat it as YAML.
// FIXME: Extend to support non-ELF and non-x86_64 binaries.
InstrumentationMap Map;
auto ObjectFileOrError = object::ObjectFile::createObjectFile(Filename);
if (!ObjectFileOrError) {
auto E = ObjectFileOrError.takeError();
// We try to load it as YAML if the ELF load didn't work.
Expected<sys::fs::file_t> FdOrErr =
sys::fs::openNativeFileForRead(Filename);
if (!FdOrErr) {
// Report the ELF load error if YAML failed.
consumeError(FdOrErr.takeError());
return std::move(E);
}
uint64_t FileSize;
if (sys::fs::file_size(Filename, FileSize))
return std::move(E);
// If the file is empty, we return the original error.
if (FileSize == 0)
return std::move(E);
// From this point on the errors will be only for the YAML parts, so we
// consume the errors at this point.
consumeError(std::move(E));
if (auto E = loadYAML(*FdOrErr, FileSize, Filename, Map.Sleds,
Map.FunctionAddresses, Map.FunctionIds))
return std::move(E);
} else if (auto E = loadObj(Filename, *ObjectFileOrError, Map.Sleds,
Map.FunctionAddresses, Map.FunctionIds)) {
return std::move(E);
}
return Map;
}
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