vendor/lld/lld-trunk-r233088

1 files changed, 527 insertions, 0 deletions

diff --git a/lib/ReaderWriter/ELF/AArch64/AArch64RelocationPass.cpp b/lib/ReaderWriter/ELF/AArch64/AArch64RelocationPass.cpp
new file mode 100644
index 0000000000000..0bd12958b27bd
--- /dev/null
+++ b/lib/ReaderWriter/ELF/AArch64/AArch64RelocationPass.cpp
@@ -0,0 +1,527 @@
+//===- lib/ReaderWriter/ELF/AArch64/AArch64RelocationPass.cpp -------------===//
+//
+//                             The LLVM Linker
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief Defines the relocation processing pass for AArch64. This includes
+///   GOT and PLT entries, TLS, COPY, and ifunc.
+///
+/// This also includes additional behavior that gnu-ld and gold implement but
+/// which is not specified anywhere.
+///
+//===----------------------------------------------------------------------===//
+
+#include "AArch64RelocationPass.h"
+#include "AArch64LinkingContext.h"
+#include "Atoms.h"
+#include "lld/Core/Simple.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Support/Debug.h"
+
+using namespace lld;
+using namespace lld::elf;
+using namespace llvm::ELF;
+
+namespace {
+// .got values
+const uint8_t AArch64GotAtomContent[8] = {0};
+
+// .plt value (entry 0)
+const uint8_t AArch64Plt0AtomContent[32] = {
+    0xf0, 0x7b, 0xbf,
+    0xa9, // stp	x16, x30, [sp,#-16]!
+    0x10, 0x00, 0x00,
+    0x90, // adrp	x16, Page(eh_frame)
+    0x11, 0x02, 0x40,
+    0xf9, // ldr	x17, [x16,#offset]
+    0x10, 0x02, 0x00,
+    0x91, // add	x16, x16, #offset
+    0x20, 0x02, 0x1f,
+    0xd6, // br	x17
+    0x1f, 0x20, 0x03,
+    0xd5, // nop
+    0x1f, 0x20, 0x03,
+    0xd5, // nop
+    0x1f, 0x20, 0x03,
+    0xd5 // nop
+};
+
+// .plt values (other entries)
+const uint8_t AArch64PltAtomContent[16] = {
+    0x10, 0x00, 0x00,
+    0x90, // adrp x16, PAGE(<GLOBAL_OFFSET_TABLE>)
+    0x11, 0x02, 0x40,
+    0xf9, // ldr x17, [x16,#offset]
+    0x10, 0x02, 0x00,
+    0x91, // add x16, x16, #offset
+    0x20, 0x02, 0x1f,
+    0xd6 // br x17
+};
+
+/// \brief Atoms that are used by AArch64 dynamic linking
+class AArch64GOTAtom : public GOTAtom {
+public:
+  AArch64GOTAtom(const File &f, StringRef secName) : GOTAtom(f, secName) {}
+
+  ArrayRef<uint8_t> rawContent() const override {
+    return ArrayRef<uint8_t>(AArch64GotAtomContent, 8);
+  }
+};
+
+class AArch64PLT0Atom : public PLT0Atom {
+public:
+  AArch64PLT0Atom(const File &f) : PLT0Atom(f) {}
+  ArrayRef<uint8_t> rawContent() const override {
+    return ArrayRef<uint8_t>(AArch64Plt0AtomContent, 32);
+  }
+};
+
+class AArch64PLTAtom : public PLTAtom {
+public:
+  AArch64PLTAtom(const File &f, StringRef secName) : PLTAtom(f, secName) {}
+
+  ArrayRef<uint8_t> rawContent() const override {
+    return ArrayRef<uint8_t>(AArch64PltAtomContent, 16);
+  }
+};
+
+class ELFPassFile : public SimpleFile {
+public:
+  ELFPassFile(const ELFLinkingContext &eti) : SimpleFile("ELFPassFile") {
+    setOrdinal(eti.getNextOrdinalAndIncrement());
+  }
+
+  llvm::BumpPtrAllocator _alloc;
+};
+
+/// \brief CRTP base for handling relocations.
+template <class Derived> class AArch64RelocationPass : public Pass {
+  /// \brief Handle a specific reference.
+  void handleReference(const DefinedAtom &atom, const Reference &ref) {
+    DEBUG_WITH_TYPE(
+        "AArch64", llvm::dbgs()
+                       << "\t" << LLVM_FUNCTION_NAME << "()"
+                       << ":   Name of Defined Atom: " << atom.name().str();
+        llvm::dbgs() << "   kindValue: " << ref.kindValue() << "\n");
+    if (ref.kindNamespace() != Reference::KindNamespace::ELF)
+      return;
+    assert(ref.kindArch() == Reference::KindArch::AArch64);
+    switch (ref.kindValue()) {
+    case R_AARCH64_ABS32:
+    case R_AARCH64_ABS16:
+    case R_AARCH64_ABS64:
+    case R_AARCH64_PREL16:
+    case R_AARCH64_PREL32:
+    case R_AARCH64_PREL64:
+      static_cast<Derived *>(this)->handlePlain(ref);
+      break;
+    case R_AARCH64_GOTREL32:
+    case R_AARCH64_GOTREL64:
+      static_cast<Derived *>(this)->handleGOT(ref);
+      break;
+    case R_AARCH64_ADR_PREL_PG_HI21:
+      static_cast<Derived *>(this)->handlePlain(ref);
+      break;
+    case R_AARCH64_LDST8_ABS_LO12_NC:
+    case R_AARCH64_LDST16_ABS_LO12_NC:
+    case R_AARCH64_LDST32_ABS_LO12_NC:
+    case R_AARCH64_LDST64_ABS_LO12_NC:
+    case R_AARCH64_LDST128_ABS_LO12_NC:
+      static_cast<Derived *>(this)->handlePlain(ref);
+      break;
+    case R_AARCH64_ADD_ABS_LO12_NC:
+      static_cast<Derived *>(this)->handlePlain(ref);
+      break;
+    case R_AARCH64_CALL26:
+    case R_AARCH64_JUMP26:
+    case R_AARCH64_CONDBR19:
+      static_cast<Derived *>(this)->handlePlain(ref);
+      break;
+    case R_AARCH64_TLSLE_ADD_TPREL_HI12:
+    case R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
+      static_cast<Derived *>(this)->handlePlain(ref);
+      break;
+    case R_AARCH64_ADR_GOT_PAGE:
+    case R_AARCH64_LD64_GOT_LO12_NC:
+    case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
+    case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
+      static_cast<Derived *>(this)->handleGOT(ref);
+      break;
+    }
+  }
+
+protected:
+  /// \brief get the PLT entry for a given IFUNC Atom.
+  ///
+  /// If the entry does not exist. Both the GOT and PLT entry is created.
+  const PLTAtom *getIFUNCPLTEntry(const DefinedAtom *da) {
+    auto plt = _pltMap.find(da);
+    if (plt != _pltMap.end())
+      return plt->second;
+    auto ga = new (_file._alloc) AArch64GOTAtom(_file, ".got.plt");
+    ga->addReferenceELF_AArch64(R_AARCH64_IRELATIVE, 0, da, 0);
+    auto pa = new (_file._alloc) AArch64PLTAtom(_file, ".plt");
+    pa->addReferenceELF_AArch64(R_AARCH64_PREL32, 2, ga, -4);
+#ifndef NDEBUG
+    ga->_name = "__got_ifunc_";
+    ga->_name += da->name();
+    pa->_name = "__plt_ifunc_";
+    pa->_name += da->name();
+#endif
+    _gotMap[da] = ga;
+    _pltMap[da] = pa;
+    _gotVector.push_back(ga);
+    _pltVector.push_back(pa);
+    return pa;
+  }
+
+  /// \brief Redirect the call to the PLT stub for the target IFUNC.
+  ///
+  /// This create a PLT and GOT entry for the IFUNC if one does not exist. The
+  /// GOT entry and a IRELATIVE relocation to the original target resolver.
+  std::error_code handleIFUNC(const Reference &ref) {
+    auto target = dyn_cast_or_null<const DefinedAtom>(ref.target());
+    if (target && target->contentType() == DefinedAtom::typeResolver)
+      const_cast<Reference &>(ref).setTarget(getIFUNCPLTEntry(target));
+    return std::error_code();
+  }
+
+  /// \brief Create a GOT entry for the TP offset of a TLS atom.
+  const GOTAtom *getGOTTPOFF(const Atom *atom) {
+    auto got = _gotMap.find(atom);
+    if (got == _gotMap.end()) {
+      auto g = new (_file._alloc) AArch64GOTAtom(_file, ".got");
+      g->addReferenceELF_AArch64(R_AARCH64_GOTREL64, 0, atom, 0);
+#ifndef NDEBUG
+      g->_name = "__got_tls_";
+      g->_name += atom->name();
+#endif
+      _gotMap[atom] = g;
+      _gotVector.push_back(g);
+      return g;
+    }
+    return got->second;
+  }
+
+  /// \brief Create a TPOFF64 GOT entry and change the relocation to a PC32 to
+  /// the GOT.
+  void handleGOTTPOFF(const Reference &ref) {
+    const_cast<Reference &>(ref).setTarget(getGOTTPOFF(ref.target()));
+    const_cast<Reference &>(ref).setKindValue(R_AARCH64_PREL32);
+  }
+
+  /// \brief Create a GOT entry containing 0.
+  const GOTAtom *getNullGOT() {
+    if (!_null) {
+      _null = new (_file._alloc) AArch64GOTAtom(_file, ".got.plt");
+#ifndef NDEBUG
+      _null->_name = "__got_null";
+#endif
+    }
+    return _null;
+  }
+
+  const GOTAtom *getGOT(const DefinedAtom *da) {
+    auto got = _gotMap.find(da);
+    if (got == _gotMap.end()) {
+      auto g = new (_file._alloc) AArch64GOTAtom(_file, ".got");
+      g->addReferenceELF_AArch64(R_AARCH64_ABS64, 0, da, 0);
+#ifndef NDEBUG
+      g->_name = "__got_";
+      g->_name += da->name();
+#endif
+      _gotMap[da] = g;
+      _gotVector.push_back(g);
+      return g;
+    }
+    return got->second;
+  }
+
+public:
+  AArch64RelocationPass(const ELFLinkingContext &ctx)
+      : _file(ctx), _ctx(ctx), _null(nullptr), _PLT0(nullptr), _got0(nullptr),
+        _got1(nullptr) {}
+
+  /// \brief Do the pass.
+  ///
+  /// The goal here is to first process each reference individually. Each call
+  /// to handleReference may modify the reference itself and/or create new
+  /// atoms which must be stored in one of the maps below.
+  ///
+  /// After all references are handled, the atoms created during that are all
+  /// added to mf.
+  void perform(std::unique_ptr<MutableFile> &mf) override {
+    ScopedTask task(getDefaultDomain(), "AArch64 GOT/PLT Pass");
+    DEBUG_WITH_TYPE(
+        "AArch64", llvm::dbgs() << "Undefined Atoms"
+                                << "\n";
+        for (const auto &atom
+             : mf->undefined()) {
+          llvm::dbgs() << " Name of Atom: " << atom->name().str() << "\n";
+        } llvm::dbgs()
+            << "Shared Library Atoms"
+            << "\n";
+        for (const auto &atom
+             : mf->sharedLibrary()) {
+          llvm::dbgs() << " Name of Atom: " << atom->name().str() << "\n";
+        } llvm::dbgs()
+            << "Absolute Atoms"
+            << "\n";
+        for (const auto &atom
+             : mf->absolute()) {
+          llvm::dbgs() << " Name of Atom: " << atom->name().str() << "\n";
+        }
+            // Process all references.
+            llvm::dbgs()
+            << "Defined Atoms"
+            << "\n");
+    for (const auto &atom : mf->defined()) {
+      for (const auto &ref : *atom) {
+        handleReference(*atom, *ref);
+      }
+    }
+
+    // Add all created atoms to the link.
+    uint64_t ordinal = 0;
+    if (_PLT0) {
+      _PLT0->setOrdinal(ordinal++);
+      mf->addAtom(*_PLT0);
+    }
+    for (auto &plt : _pltVector) {
+      plt->setOrdinal(ordinal++);
+      mf->addAtom(*plt);
+    }
+    if (_null) {
+      _null->setOrdinal(ordinal++);
+      mf->addAtom(*_null);
+    }
+    if (_PLT0) {
+      _got0->setOrdinal(ordinal++);
+      _got1->setOrdinal(ordinal++);
+      mf->addAtom(*_got0);
+      mf->addAtom(*_got1);
+    }
+    for (auto &got : _gotVector) {
+      got->setOrdinal(ordinal++);
+      mf->addAtom(*got);
+    }
+    for (auto obj : _objectVector) {
+      obj->setOrdinal(ordinal++);
+      mf->addAtom(*obj);
+    }
+  }
+
+protected:
+  /// \brief Owner of all the Atoms created by this pass.
+  ELFPassFile _file;
+  const ELFLinkingContext &_ctx;
+
+  /// \brief Map Atoms to their GOT entries.
+  llvm::DenseMap<const Atom *, GOTAtom *> _gotMap;
+
+  /// \brief Map Atoms to their PLT entries.
+  llvm::DenseMap<const Atom *, PLTAtom *> _pltMap;
+
+  /// \brief Map Atoms to their Object entries.
+  llvm::DenseMap<const Atom *, ObjectAtom *> _objectMap;
+
+  /// \brief the list of GOT/PLT atoms
+  std::vector<GOTAtom *> _gotVector;
+  std::vector<PLTAtom *> _pltVector;
+  std::vector<ObjectAtom *> _objectVector;
+
+  /// \brief GOT entry that is always 0. Used for undefined weaks.
+  GOTAtom *_null;
+
+  /// \brief The got and plt entries for .PLT0. This is used to call into the
+  /// dynamic linker for symbol resolution.
+  /// @{
+  PLT0Atom *_PLT0;
+  GOTAtom *_got0;
+  GOTAtom *_got1;
+  /// @}
+};
+
+/// This implements the static relocation model. Meaning GOT and PLT entries are
+/// not created for references that can be directly resolved. These are
+/// converted to a direct relocation. For entries that do require a GOT or PLT
+/// entry, that entry is statically bound.
+///
+/// TLS always assumes module 1 and attempts to remove indirection.
+class AArch64StaticRelocationPass final
+    : public AArch64RelocationPass<AArch64StaticRelocationPass> {
+public:
+  AArch64StaticRelocationPass(const elf::AArch64LinkingContext &ctx)
+      : AArch64RelocationPass(ctx) {}
+
+  std::error_code handlePlain(const Reference &ref) { return handleIFUNC(ref); }
+
+  std::error_code handlePLT32(const Reference &ref) {
+    // __tls_get_addr is handled elsewhere.
+    if (ref.target() && ref.target()->name() == "__tls_get_addr") {
+      const_cast<Reference &>(ref).setKindValue(R_AARCH64_NONE);
+      return std::error_code();
+    }
+    // Static code doesn't need PLTs.
+    const_cast<Reference &>(ref).setKindValue(R_AARCH64_PREL32);
+    // Handle IFUNC.
+    if (const DefinedAtom *da =
+            dyn_cast_or_null<const DefinedAtom>(ref.target()))
+      if (da->contentType() == DefinedAtom::typeResolver)
+        return handleIFUNC(ref);
+    return std::error_code();
+  }
+
+  std::error_code handleGOT(const Reference &ref) {
+    if (isa<UndefinedAtom>(ref.target()))
+      const_cast<Reference &>(ref).setTarget(getNullGOT());
+    else if (const DefinedAtom *da = dyn_cast<const DefinedAtom>(ref.target()))
+      const_cast<Reference &>(ref).setTarget(getGOT(da));
+    return std::error_code();
+  }
+};
+
+class AArch64DynamicRelocationPass final
+    : public AArch64RelocationPass<AArch64DynamicRelocationPass> {
+public:
+  AArch64DynamicRelocationPass(const elf::AArch64LinkingContext &ctx)
+      : AArch64RelocationPass(ctx) {}
+
+  const PLT0Atom *getPLT0() {
+    if (_PLT0)
+      return _PLT0;
+    // Fill in the null entry.
+    getNullGOT();
+    _PLT0 = new (_file._alloc) AArch64PLT0Atom(_file);
+    _got0 = new (_file._alloc) AArch64GOTAtom(_file, ".got.plt");
+    _got1 = new (_file._alloc) AArch64GOTAtom(_file, ".got.plt");
+    _PLT0->addReferenceELF_AArch64(R_AARCH64_ADR_GOT_PAGE, 4, _got0, 0);
+    _PLT0->addReferenceELF_AArch64(R_AARCH64_LD64_GOT_LO12_NC, 8, _got1, 0);
+    _PLT0->addReferenceELF_AArch64(ADD_AARCH64_GOTRELINDEX, 12, _got1, 0);
+#ifndef NDEBUG
+    _PLT0->_name = "__PLT0";
+    _got0->_name = "__got0";
+    _got1->_name = "__got1";
+#endif
+    return _PLT0;
+  }
+
+  const PLTAtom *getPLTEntry(const Atom *a) {
+    auto plt = _pltMap.find(a);
+    if (plt != _pltMap.end())
+      return plt->second;
+    auto ga = new (_file._alloc) AArch64GOTAtom(_file, ".got.plt");
+    ga->addReferenceELF_AArch64(R_AARCH64_JUMP_SLOT, 0, a, 0);
+    auto pa = new (_file._alloc) AArch64PLTAtom(_file, ".plt");
+    pa->addReferenceELF_AArch64(R_AARCH64_ADR_GOT_PAGE, 0, ga, 0);
+    pa->addReferenceELF_AArch64(R_AARCH64_LD64_GOT_LO12_NC, 4, ga, 0);
+    pa->addReferenceELF_AArch64(ADD_AARCH64_GOTRELINDEX, 8, ga, 0);
+    pa->addReferenceELF_AArch64(R_AARCH64_NONE, 12, getPLT0(), 0);
+    // Set the starting address of the got entry to the first instruction in
+    // the plt0 entry.
+    ga->addReferenceELF_AArch64(R_AARCH64_ABS32, 0, getPLT0(), 0);
+#ifndef NDEBUG
+    ga->_name = "__got_";
+    ga->_name += a->name();
+    pa->_name = "__plt_";
+    pa->_name += a->name();
+#endif
+    _gotMap[a] = ga;
+    _pltMap[a] = pa;
+    _gotVector.push_back(ga);
+    _pltVector.push_back(pa);
+    return pa;
+  }
+
+  const ObjectAtom *getObjectEntry(const SharedLibraryAtom *a) {
+    auto obj = _objectMap.find(a);
+    if (obj != _objectMap.end())
+      return obj->second;
+
+    auto oa = new (_file._alloc) ObjectAtom(_file);
+    // This needs to point to the atom that we just created.
+    oa->addReferenceELF_AArch64(R_AARCH64_COPY, 0, oa, 0);
+
+    oa->_name = a->name();
+    oa->_size = a->size();
+
+    _objectMap[a] = oa;
+    _objectVector.push_back(oa);
+    return oa;
+  }
+
+  std::error_code handlePlain(const Reference &ref) {
+    if (!ref.target())
+      return std::error_code();
+    if (auto sla = dyn_cast<SharedLibraryAtom>(ref.target())) {
+      if (sla->type() == SharedLibraryAtom::Type::Data)
+        const_cast<Reference &>(ref).setTarget(getObjectEntry(sla));
+      else if (sla->type() == SharedLibraryAtom::Type::Code)
+        const_cast<Reference &>(ref).setTarget(getPLTEntry(sla));
+    } else
+      return handleIFUNC(ref);
+    return std::error_code();
+  }
+
+  std::error_code handlePLT32(const Reference &ref) {
+    // Turn this into a PC32 to the PLT entry.
+    const_cast<Reference &>(ref).setKindValue(R_AARCH64_PREL32);
+    // Handle IFUNC.
+    if (const DefinedAtom *da =
+            dyn_cast_or_null<const DefinedAtom>(ref.target()))
+      if (da->contentType() == DefinedAtom::typeResolver)
+        return handleIFUNC(ref);
+    if (isa<const SharedLibraryAtom>(ref.target()))
+      const_cast<Reference &>(ref).setTarget(getPLTEntry(ref.target()));
+    return std::error_code();
+  }
+
+  const GOTAtom *getSharedGOT(const SharedLibraryAtom *sla) {
+    auto got = _gotMap.find(sla);
+    if (got == _gotMap.end()) {
+      auto g = new (_file._alloc) AArch64GOTAtom(_file, ".got");
+      g->addReferenceELF_AArch64(R_AARCH64_GLOB_DAT, 0, sla, 0);
+#ifndef NDEBUG
+      g->_name = "__got_";
+      g->_name += sla->name();
+#endif
+      _gotMap[sla] = g;
+      _gotVector.push_back(g);
+      return g;
+    }
+    return got->second;
+  }
+
+  std::error_code handleGOT(const Reference &ref) {
+    if (isa<UndefinedAtom>(ref.target()))
+      const_cast<Reference &>(ref).setTarget(getNullGOT());
+    else if (const DefinedAtom *da = dyn_cast<const DefinedAtom>(ref.target()))
+      const_cast<Reference &>(ref).setTarget(getGOT(da));
+    else if (const auto sla = dyn_cast<const SharedLibraryAtom>(ref.target()))
+      const_cast<Reference &>(ref).setTarget(getSharedGOT(sla));
+    return std::error_code();
+  }
+};
+} // end anon namespace
+
+std::unique_ptr<Pass>
+lld::elf::createAArch64RelocationPass(const AArch64LinkingContext &ctx) {
+  switch (ctx.getOutputELFType()) {
+  case llvm::ELF::ET_EXEC:
+    if (ctx.isDynamic())
+      return llvm::make_unique<AArch64DynamicRelocationPass>(ctx);
+    return llvm::make_unique<AArch64StaticRelocationPass>(ctx);
+  case llvm::ELF::ET_DYN:
+    return llvm::make_unique<AArch64DynamicRelocationPass>(ctx);
+  case llvm::ELF::ET_REL:
+    return nullptr;
+  default:
+    llvm_unreachable("Unhandled output file type");
+  }
+}