160 lines · cpp
1//===-- llvm-jitlink-macho.cpp -- MachO parsing support for llvm-jitlink --===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8//9// MachO parsing support for llvm-jitlink.10//11//===----------------------------------------------------------------------===//12 13#include "llvm-jitlink.h"14 15#include "llvm/Support/Error.h"16#include "llvm/Support/Path.h"17 18#define DEBUG_TYPE "llvm_jitlink"19 20using namespace llvm;21using namespace llvm::jitlink;22 23static bool isMachOGOTSection(Section &S) { return S.getName() == "$__GOT"; }24 25static bool isMachOStubsSection(Section &S) {26 return S.getName() == "$__STUBS";27}28 29static Expected<Edge &> getFirstRelocationEdge(LinkGraph &G, Block &B) {30 auto EItr =31 llvm::find_if(B.edges(), [](Edge &E) { return E.isRelocation(); });32 if (EItr == B.edges().end())33 return make_error<StringError>("GOT entry in " + G.getName() + ", \"" +34 B.getSection().getName() +35 "\" has no relocations",36 inconvertibleErrorCode());37 return *EItr;38}39 40static Expected<Symbol &> getMachOGOTTarget(LinkGraph &G, Block &B) {41 auto E = getFirstRelocationEdge(G, B);42 if (!E)43 return E.takeError();44 auto &TargetSym = E->getTarget();45 if (!TargetSym.hasName())46 return make_error<StringError>(47 "GOT entry in " + G.getName() + ", \"" +48 TargetSym.getBlock().getSection().getName() +49 "\" points to anonymous "50 "symbol",51 inconvertibleErrorCode());52 return TargetSym;53}54 55static Expected<Symbol &> getMachOStubTarget(LinkGraph &G, Block &B) {56 auto E = getFirstRelocationEdge(G, B);57 if (!E)58 return E.takeError();59 auto &GOTSym = E->getTarget();60 if (!GOTSym.isDefined() || !isMachOGOTSection(GOTSym.getBlock().getSection()))61 return make_error<StringError>(62 "Stubs entry in " + G.getName() + ", \"" +63 GOTSym.getBlock().getSection().getName() +64 "\" does not point to GOT entry",65 inconvertibleErrorCode());66 return getMachOGOTTarget(G, GOTSym.getBlock());67}68 69namespace llvm {70 71Error registerMachOGraphInfo(Session &S, LinkGraph &G) {72 std::lock_guard<std::mutex> Lock(S.M);73 74 auto FileName = sys::path::filename(G.getName());75 auto [It, Inserted] = S.FileInfos.try_emplace(FileName);76 if (!Inserted) {77 return make_error<StringError>("When -check is passed, file names must be "78 "distinct (duplicate: \"" +79 FileName + "\")",80 inconvertibleErrorCode());81 }82 83 auto &FileInfo = It->second;84 LLVM_DEBUG({85 dbgs() << "Registering MachO file info for \"" << FileName << "\"\n";86 });87 for (auto &Sec : G.sections()) {88 LLVM_DEBUG({89 dbgs() << " Section \"" << Sec.getName() << "\": "90 << (Sec.symbols().empty() ? "empty. skipping." : "processing...")91 << "\n";92 });93 94 // Skip empty sections.95 if (Sec.symbols().empty())96 continue;97 98 if (FileInfo.SectionInfos.count(Sec.getName()))99 return make_error<StringError>("Encountered duplicate section name \"" +100 Sec.getName() + "\" in \"" + FileName +101 "\"",102 inconvertibleErrorCode());103 104 bool isGOTSection = isMachOGOTSection(Sec);105 bool isStubsSection = isMachOStubsSection(Sec);106 107 bool SectionContainsContent = false;108 bool SectionContainsZeroFill = false;109 110 auto *FirstSym = *Sec.symbols().begin();111 auto *LastSym = FirstSym;112 for (auto *Sym : Sec.symbols()) {113 if (Sym->getAddress() < FirstSym->getAddress())114 FirstSym = Sym;115 if (Sym->getAddress() > LastSym->getAddress())116 LastSym = Sym;117 if (isGOTSection || isStubsSection) {118 Error Err =119 isGOTSection120 ? FileInfo.registerGOTEntry(G, *Sym, getMachOGOTTarget)121 : FileInfo.registerStubEntry(G, *Sym, getMachOStubTarget);122 if (Err)123 return Err;124 SectionContainsContent = true;125 } else if (Sym->hasName()) {126 if (Sym->isSymbolZeroFill()) {127 S.SymbolInfos[Sym->getName()] = {Sym->getSize(),128 Sym->getAddress().getValue()};129 SectionContainsZeroFill = true;130 } else {131 S.SymbolInfos[Sym->getName()] = {Sym->getSymbolContent(),132 Sym->getAddress().getValue(),133 Sym->getTargetFlags()};134 SectionContainsContent = true;135 }136 }137 }138 139 auto SecAddr = FirstSym->getAddress();140 auto SecSize =141 (LastSym->getBlock().getAddress() + LastSym->getBlock().getSize()) -142 SecAddr;143 144 if (SectionContainsZeroFill && SectionContainsContent)145 return make_error<StringError>("Mixed zero-fill and content sections not "146 "supported yet",147 inconvertibleErrorCode());148 if (SectionContainsZeroFill)149 FileInfo.SectionInfos[Sec.getName()] = {SecSize, SecAddr.getValue()};150 else151 FileInfo.SectionInfos[Sec.getName()] = {152 ArrayRef<char>(FirstSym->getBlock().getContent().data(), SecSize),153 SecAddr.getValue(), FirstSym->getTargetFlags()};154 }155 156 return Error::success();157}158 159} // end namespace llvm160