1 //===--- llvm-jitlink-coff.cpp -- COFF 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 // COFF 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 isCOFFGOTSection(Section &S) { return S.getName() == "$__GOT"; } 24 25 static bool isCOFFStubsSection(Section &S) { return S.getName() == "$__STUBS"; } 26 27 static Expected<Edge &> getFirstRelocationEdge(LinkGraph &G, Block &B) { 28 auto EItr = 29 llvm::find_if(B.edges(), [](Edge &E) { return E.isRelocation(); }); 30 if (EItr == B.edges().end()) 31 return make_error<StringError>("GOT entry in " + G.getName() + ", \"" + 32 B.getSection().getName() + 33 "\" has no relocations", 34 inconvertibleErrorCode()); 35 return *EItr; 36 } 37 38 static Expected<Symbol &> getCOFFGOTTarget(LinkGraph &G, Block &B) { 39 auto E = getFirstRelocationEdge(G, B); 40 if (!E) 41 return E.takeError(); 42 auto &TargetSym = E->getTarget(); 43 if (!TargetSym.hasName()) 44 return make_error<StringError>( 45 "GOT entry in " + G.getName() + ", \"" + 46 TargetSym.getBlock().getSection().getName() + 47 "\" points to anonymous " 48 "symbol", 49 inconvertibleErrorCode()); 50 return TargetSym; 51 } 52 53 static Expected<Symbol &> getCOFFStubTarget(LinkGraph &G, Block &B) { 54 auto E = getFirstRelocationEdge(G, B); 55 if (!E) 56 return E.takeError(); 57 auto &GOTSym = E->getTarget(); 58 if (!GOTSym.isDefined() || !isCOFFGOTSection(GOTSym.getBlock().getSection())) 59 return make_error<StringError>( 60 "Stubs entry in " + G.getName() + ", \"" + 61 GOTSym.getBlock().getSection().getName() + 62 "\" does not point to GOT entry", 63 inconvertibleErrorCode()); 64 return getCOFFGOTTarget(G, GOTSym.getBlock()); 65 } 66 67 namespace llvm { 68 Error registerCOFFGraphInfo(Session &S, LinkGraph &G) { 69 std::lock_guard<std::mutex> Lock(S.M); 70 71 auto FileName = sys::path::filename(G.getName()); 72 if (S.FileInfos.count(FileName)) { 73 return make_error<StringError>("When -check is passed, file names must be " 74 "distinct (duplicate: \"" + 75 FileName + "\")", 76 inconvertibleErrorCode()); 77 } 78 79 auto &FileInfo = S.FileInfos[FileName]; 80 LLVM_DEBUG( 81 { dbgs() << "Registering COFF file info for \"" << FileName << "\"\n"; }); 82 for (auto &Sec : G.sections()) { 83 LLVM_DEBUG({ 84 dbgs() << " Section \"" << Sec.getName() << "\": " 85 << (Sec.symbols().empty() ? "empty. skipping." : "processing...") 86 << "\n"; 87 }); 88 89 // Skip empty sections. 90 if (Sec.symbols().empty()) 91 continue; 92 93 if (FileInfo.SectionInfos.count(Sec.getName())) 94 return make_error<StringError>("Encountered duplicate section name \"" + 95 Sec.getName() + "\" in \"" + FileName + 96 "\"", 97 inconvertibleErrorCode()); 98 99 bool isGOTSection = isCOFFGOTSection(Sec); 100 bool isStubsSection = isCOFFStubsSection(Sec); 101 102 bool SectionContainsContent = false; 103 bool SectionContainsZeroFill = false; 104 105 auto *FirstSym = *Sec.symbols().begin(); 106 auto *LastSym = FirstSym; 107 for (auto *Sym : Sec.symbols()) { 108 if (Sym->getAddress() < FirstSym->getAddress()) 109 FirstSym = Sym; 110 if (Sym->getAddress() > LastSym->getAddress()) 111 LastSym = Sym; 112 113 if (isGOTSection || isStubsSection) { 114 if (isGOTSection) { 115 // Skip the GOT start symbol 116 if (Sym->getSize() != 0) 117 if (Error E = FileInfo.registerGOTEntry(G, *Sym, getCOFFGOTTarget)) 118 return E; 119 } else { 120 if (Error E = FileInfo.registerStubEntry(G, *Sym, getCOFFStubTarget)) 121 return E; 122 } 123 SectionContainsContent = true; 124 } 125 126 if (Sym->hasName()) { 127 if (Sym->isSymbolZeroFill()) { 128 S.SymbolInfos[Sym->getName()] = {Sym->getSize(), 129 Sym->getAddress().getValue()}; 130 SectionContainsZeroFill = true; 131 } else { 132 S.SymbolInfos[Sym->getName()] = {Sym->getSymbolContent(), 133 Sym->getAddress().getValue(), 134 Sym->getTargetFlags()}; 135 SectionContainsContent = true; 136 } 137 } 138 } 139 140 auto SecAddr = FirstSym->getAddress(); 141 auto SecSize = 142 (LastSym->getBlock().getAddress() + LastSym->getBlock().getSize()) - 143 SecAddr; 144 145 if (SectionContainsZeroFill && SectionContainsContent) 146 return make_error<StringError>("Mixed zero-fill and content sections not " 147 "supported yet", 148 inconvertibleErrorCode()); 149 150 if (SectionContainsZeroFill) 151 FileInfo.SectionInfos[Sec.getName()] = {SecSize, SecAddr.getValue()}; 152 else 153 FileInfo.SectionInfos[Sec.getName()] = { 154 ArrayRef<char>(FirstSym->getBlock().getContent().data(), SecSize), 155 SecAddr.getValue(), FirstSym->getTargetFlags()}; 156 } 157 158 return Error::success(); 159 } 160 161 } // end namespace llvm 162