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-exception 6 // 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 20 using namespace llvm; 21 using namespace llvm::jitlink; 22 23 static bool isMachOGOTSection(Section &S) { return S.getName() == "$__GOT"; } 24 25 static bool isMachOStubsSection(Section &S) { 26 return S.getName() == "$__STUBS"; 27 } 28 29 static 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 40 static 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 55 static 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 69 namespace llvm { 70 71 Error registerMachOGraphInfo(Session &S, LinkGraph &G) { 72 auto FileName = sys::path::filename(G.getName()); 73 if (S.FileInfos.count(FileName)) { 74 return make_error<StringError>("When -check is passed, file names must be " 75 "distinct (duplicate: \"" + 76 FileName + "\")", 77 inconvertibleErrorCode()); 78 } 79 80 auto &FileInfo = S.FileInfos[FileName]; 81 LLVM_DEBUG({ 82 dbgs() << "Registering MachO file info for \"" << FileName << "\"\n"; 83 }); 84 for (auto &Sec : G.sections()) { 85 LLVM_DEBUG({ 86 dbgs() << " Section \"" << Sec.getName() << "\": " 87 << (Sec.symbols().empty() ? "empty. skipping." : "processing...") 88 << "\n"; 89 }); 90 91 // Skip empty sections. 92 if (Sec.symbols().empty()) 93 continue; 94 95 if (FileInfo.SectionInfos.count(Sec.getName())) 96 return make_error<StringError>("Encountered duplicate section name \"" + 97 Sec.getName() + "\" in \"" + FileName + 98 "\"", 99 inconvertibleErrorCode()); 100 101 bool isGOTSection = isMachOGOTSection(Sec); 102 bool isStubsSection = isMachOStubsSection(Sec); 103 104 bool SectionContainsContent = false; 105 bool SectionContainsZeroFill = false; 106 107 auto *FirstSym = *Sec.symbols().begin(); 108 auto *LastSym = FirstSym; 109 for (auto *Sym : Sec.symbols()) { 110 if (Sym->getAddress() < FirstSym->getAddress()) 111 FirstSym = Sym; 112 if (Sym->getAddress() > LastSym->getAddress()) 113 LastSym = Sym; 114 if (isGOTSection) { 115 if (Sym->isSymbolZeroFill()) 116 return make_error<StringError>("zero-fill atom in GOT section", 117 inconvertibleErrorCode()); 118 119 if (auto TS = getMachOGOTTarget(G, Sym->getBlock())) 120 FileInfo.GOTEntryInfos[TS->getName()] = {Sym->getSymbolContent(), 121 Sym->getAddress().getValue(), 122 Sym->getTargetFlags()}; 123 else 124 return TS.takeError(); 125 SectionContainsContent = true; 126 } else if (isStubsSection) { 127 if (Sym->isSymbolZeroFill()) 128 return make_error<StringError>("zero-fill atom in Stub section", 129 inconvertibleErrorCode()); 130 131 if (auto TS = getMachOStubTarget(G, Sym->getBlock())) 132 FileInfo.StubInfos[TS->getName()] = {Sym->getSymbolContent(), 133 Sym->getAddress().getValue(), 134 Sym->getTargetFlags()}; 135 else 136 return TS.takeError(); 137 SectionContainsContent = true; 138 } else if (Sym->hasName()) { 139 if (Sym->isSymbolZeroFill()) { 140 S.SymbolInfos[Sym->getName()] = {Sym->getSize(), 141 Sym->getAddress().getValue()}; 142 SectionContainsZeroFill = true; 143 } else { 144 S.SymbolInfos[Sym->getName()] = {Sym->getSymbolContent(), 145 Sym->getAddress().getValue(), 146 Sym->getTargetFlags()}; 147 SectionContainsContent = true; 148 } 149 } 150 } 151 152 auto SecAddr = FirstSym->getAddress(); 153 auto SecSize = 154 (LastSym->getBlock().getAddress() + LastSym->getBlock().getSize()) - 155 SecAddr; 156 157 if (SectionContainsZeroFill && SectionContainsContent) 158 return make_error<StringError>("Mixed zero-fill and content sections not " 159 "supported yet", 160 inconvertibleErrorCode()); 161 if (SectionContainsZeroFill) 162 FileInfo.SectionInfos[Sec.getName()] = {SecSize, SecAddr.getValue()}; 163 else 164 FileInfo.SectionInfos[Sec.getName()] = { 165 ArrayRef<char>(FirstSym->getBlock().getContent().data(), SecSize), 166 SecAddr.getValue(), FirstSym->getTargetFlags()}; 167 } 168 169 return Error::success(); 170 } 171 172 } // end namespace llvm 173