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