tools/llvm-jitlink/llvm-jitlink-macho.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-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(AtomGraph &G, DefinedAtom &DA) {
  30   auto EItr = std::find_if(DA.edges().begin(), DA.edges().end(),
  31                            [](Edge &E) { return E.isRelocation(); });
  32   if (EItr == DA.edges().end())
  33     return make_error<StringError>("GOT entry in " + G.getName() + ", \"" +
  34                                        DA.getSection().getName() +
  35                                        "\" has no relocations",
  36                                    inconvertibleErrorCode());
  37   return *EItr;
  38 }
  39
  40 static Expected<Atom &> getMachOGOTTarget(AtomGraph &G, DefinedAtom &DA) {
  41   auto E = getFirstRelocationEdge(G, DA);
  42   if (!E)
  43     return E.takeError();
  44   auto &TA = E->getTarget();
  45   if (!TA.hasName())
  46     return make_error<StringError>("GOT entry in " + G.getName() + ", \"" +
  47                                        DA.getSection().getName() +
  48                                        "\" points to anonymous "
  49                                        "atom",
  50                                    inconvertibleErrorCode());
  51   if (TA.isDefined() || TA.isAbsolute())
  52     return make_error<StringError>(
  53         "GOT entry \"" + TA.getName() + "\" in " + G.getName() + ", \"" +
  54             DA.getSection().getName() + "\" does not point to an external atom",
  55         inconvertibleErrorCode());
  56   return TA;
  57 }
  58
  59 static Expected<Atom &> getMachOStubTarget(AtomGraph &G, DefinedAtom &DA) {
  60   auto E = getFirstRelocationEdge(G, DA);
  61   if (!E)
  62     return E.takeError();
  63   auto &GOTA = E->getTarget();
  64   if (!GOTA.isDefined() ||
  65       !isMachOGOTSection(static_cast<DefinedAtom &>(GOTA).getSection()))
  66     return make_error<StringError>("Stubs entry in " + G.getName() + ", \"" +
  67                                        DA.getSection().getName() +
  68                                        "\" does not point to GOT entry",
  69                                    inconvertibleErrorCode());
  70   return getMachOGOTTarget(G, static_cast<DefinedAtom &>(GOTA));
  71 }
  72
  73 namespace llvm {
  74
  75 Error registerMachOStubsAndGOT(Session &S, AtomGraph &G) {
  76   auto FileName = sys::path::filename(G.getName());
  77   if (S.FileInfos.count(FileName)) {
  78     return make_error<StringError>("When -check is passed, file names must be "
  79                                    "distinct (duplicate: \"" +
  80                                        FileName + "\")",
  81                                    inconvertibleErrorCode());
  82   }
  83
  84   auto &FileInfo = S.FileInfos[FileName];
  85   LLVM_DEBUG({
  86     dbgs() << "Registering MachO file info for \"" << FileName << "\"\n";
  87   });
  88   for (auto &Sec : G.sections()) {
  89     LLVM_DEBUG({
  90       dbgs() << "  Section \"" << Sec.getName() << "\": "
  91              << (Sec.atoms_empty() ? "empty. skipping." : "processing...")
  92              << "\n";
  93     });
  94
  95     // Skip empty sections.
  96     if (Sec.atoms_empty())
  97       continue;
  98
  99     if (FileInfo.SectionInfos.count(Sec.getName()))
 100       return make_error<StringError>("Encountered duplicate section name \"" +
 101                                          Sec.getName() + "\" in \"" + FileName +
 102                                          "\"",
 103                                      inconvertibleErrorCode());
 104
 105     bool isGOTSection = isMachOGOTSection(Sec);
 106     bool isStubsSection = isMachOStubsSection(Sec);
 107
 108     auto *FirstAtom = *Sec.atoms().begin();
 109     auto *LastAtom = FirstAtom;
 110     for (auto *DA : Sec.atoms()) {
 111       if (DA->getAddress() < FirstAtom->getAddress())
 112         FirstAtom = DA;
 113       if (DA->getAddress() > LastAtom->getAddress())
 114         LastAtom = DA;
 115       if (isGOTSection) {
 116         if (Sec.isZeroFill())
 117           return make_error<StringError>("Content atom in zero-fill section",
 118                                          inconvertibleErrorCode());
 119
 120         if (auto TA = getMachOGOTTarget(G, *DA)) {
 121           FileInfo.GOTEntryInfos[TA->getName()] = {DA->getContent(),
 122                                                    DA->getAddress()};
 123         } else
 124           return TA.takeError();
 125       } else if (isStubsSection) {
 126         if (Sec.isZeroFill())
 127           return make_error<StringError>("Content atom in zero-fill section",
 128                                          inconvertibleErrorCode());
 129
 130         if (auto TA = getMachOStubTarget(G, *DA))
 131           FileInfo.StubInfos[TA->getName()] = {DA->getContent(),
 132                                                DA->getAddress()};
 133         else
 134           return TA.takeError();
 135       } else if (DA->hasName() && DA->isGlobal()) {
 136         if (DA->isZeroFill())
 137           S.SymbolInfos[DA->getName()] = {DA->getSize(), DA->getAddress()};
 138         else {
 139           if (Sec.isZeroFill())
 140             return make_error<StringError>("Content atom in zero-fill section",
 141                                            inconvertibleErrorCode());
 142           S.SymbolInfos[DA->getName()] = {DA->getContent(), DA->getAddress()};
 143         }
 144       }
 145     }
 146
 147     JITTargetAddress SecAddr = FirstAtom->getAddress();
 148     uint64_t SecSize = (LastAtom->getAddress() + LastAtom->getSize()) -
 149                        FirstAtom->getAddress();
 150
 151     if (Sec.isZeroFill())
 152       FileInfo.SectionInfos[Sec.getName()] = {SecSize, SecAddr};
 153     else
 154       FileInfo.SectionInfos[Sec.getName()] = {
 155           StringRef(FirstAtom->getContent().data(), SecSize), SecAddr};
 156   }
 157
 158   return Error::success();
 159 }
 160
 161 } // end namespace llvm