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Diffstat (limited to 'lld/lib/ReaderWriter/ELF/ARM/ARMRelocationPass.cpp')
| -rw-r--r-- | lld/lib/ReaderWriter/ELF/ARM/ARMRelocationPass.cpp | 986 |
1 files changed, 0 insertions, 986 deletions
diff --git a/lld/lib/ReaderWriter/ELF/ARM/ARMRelocationPass.cpp b/lld/lib/ReaderWriter/ELF/ARM/ARMRelocationPass.cpp deleted file mode 100644 index a47f0771c91..00000000000 --- a/lld/lib/ReaderWriter/ELF/ARM/ARMRelocationPass.cpp +++ /dev/null @@ -1,986 +0,0 @@ -//===--------- lib/ReaderWriter/ELF/ARM/ARMRelocationPass.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 ARM. 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 "ARMRelocationPass.h" -#include "ARMLinkingContext.h" -#include "Atoms.h" -#include "lld/Core/Simple.h" -#include "llvm/ADT/MapVector.h" -#include "llvm/ADT/STLExtras.h" -#include "llvm/Support/Debug.h" - -using namespace lld; -using namespace lld::elf; -using namespace llvm::ELF; - -namespace { -// ARM B/BL instructions of absolute relocation veneer. -// TODO: consider different instruction set for archs below ARMv5 -// (one as for Thumb may be used though it's less optimal). -static const uint8_t Veneer_ARM_B_BL_Abs_a_AtomContent[4] = { - 0x04, 0xf0, 0x1f, 0xe5 // ldr pc, [pc, #-4] -}; -static const uint8_t Veneer_ARM_B_BL_Abs_d_AtomContent[4] = { - 0x00, 0x00, 0x00, 0x00 // <target_symbol_address> -}; - -// Thumb B/BL instructions of absolute relocation veneer. -// TODO: consider different instruction set for archs above ARMv5 -// (one as for ARM may be used since it's more optimal). -static const uint8_t Veneer_THM_B_BL_Abs_t_AtomContent[4] = { - 0x78, 0x47, // bx pc - 0x00, 0x00 // nop -}; -static const uint8_t Veneer_THM_B_BL_Abs_a_AtomContent[4] = { - 0xfe, 0xff, 0xff, 0xea // b <target_symbol_address> -}; - -// .got values -static const uint8_t ARMGotAtomContent[4] = {0}; - -// .plt value (entry 0) -static const uint8_t ARMPlt0_a_AtomContent[16] = { - 0x04, 0xe0, 0x2d, 0xe5, // push {lr} - 0x04, 0xe0, 0x9f, 0xe5, // ldr lr, [pc, #4] - 0x0e, 0xe0, 0x8f, 0xe0, // add lr, pc, lr - 0x00, 0xf0, 0xbe, 0xe5 // ldr pc, [lr, #0]! -}; -static const uint8_t ARMPlt0_d_AtomContent[4] = { - 0x00, 0x00, 0x00, 0x00 // <got1_symbol_address> -}; - -// .plt values (other entries) -static const uint8_t ARMPltAtomContent[12] = { - 0x00, 0xc0, 0x8f, 0xe2, // add ip, pc, #offset[G0] - 0x00, 0xc0, 0x8c, 0xe2, // add ip, ip, #offset[G1] - 0x00, 0xf0, 0xbc, 0xe5 // ldr pc, [ip, #offset[G2]]! -}; - -// Veneer for switching from Thumb to ARM code for PLT entries. -static const uint8_t ARMPltVeneerAtomContent[4] = { - 0x78, 0x47, // bx pc - 0x00, 0x00 // nop -}; - -// Determine proper names for mapping symbols. -static std::string getMappingAtomName(DefinedAtom::CodeModel model, - const std::string &part) { - switch (model) { - case DefinedAtom::codeARM_a: - return part.empty() ? "$a" : "$a." + part; - case DefinedAtom::codeARM_d: - return part.empty() ? "$d" : "$d." + part; - case DefinedAtom::codeARM_t: - return part.empty() ? "$t" : "$t." + part; - default: - llvm_unreachable("Wrong code model of mapping atom"); - } -} - -/// \brief Atoms that hold veneer code. -class VeneerAtom : public SimpleELFDefinedAtom { - StringRef _section; - -public: - VeneerAtom(const File &f, StringRef secName, const std::string &name = "") - : SimpleELFDefinedAtom(f), _section(secName), _name(name) {} - - Scope scope() const override { return DefinedAtom::scopeTranslationUnit; } - - SectionChoice sectionChoice() const override { - return DefinedAtom::sectionBasedOnContent; - } - - StringRef customSectionName() const override { return _section; } - - ContentType contentType() const override { return DefinedAtom::typeCode; } - - uint64_t size() const override { return rawContent().size(); } - - ContentPermissions permissions() const override { return permR_X; } - - Alignment alignment() const override { return 4; } - - StringRef name() const override { return _name; } - -private: - std::string _name; -}; - -/// \brief Atoms that hold veneer for relocated ARM B/BL instructions -/// in absolute code. -class Veneer_ARM_B_BL_Abs_a_Atom : public VeneerAtom { -public: - Veneer_ARM_B_BL_Abs_a_Atom(const File &f, StringRef secName, - const std::string &name) - : VeneerAtom(f, secName, name) {} - - ArrayRef<uint8_t> rawContent() const override { - return llvm::makeArrayRef(Veneer_ARM_B_BL_Abs_a_AtomContent); - } -}; - -class Veneer_ARM_B_BL_Abs_d_Atom : public VeneerAtom { -public: - Veneer_ARM_B_BL_Abs_d_Atom(const File &f, StringRef secName) - : VeneerAtom(f, secName) {} - - ArrayRef<uint8_t> rawContent() const override { - return llvm::makeArrayRef(Veneer_ARM_B_BL_Abs_d_AtomContent); - } -}; - -/// \brief Atoms that hold veneer for relocated Thumb B/BL instructions -/// in absolute code. -class Veneer_THM_B_BL_Abs_t_Atom : public VeneerAtom { -public: - Veneer_THM_B_BL_Abs_t_Atom(const File &f, StringRef secName, - const std::string &name) - : VeneerAtom(f, secName, name) {} - - DefinedAtom::CodeModel codeModel() const override { - return DefinedAtom::codeARMThumb; - } - - ArrayRef<uint8_t> rawContent() const override { - return llvm::makeArrayRef(Veneer_THM_B_BL_Abs_t_AtomContent); - } -}; - -class Veneer_THM_B_BL_Abs_a_Atom : public VeneerAtom { -public: - Veneer_THM_B_BL_Abs_a_Atom(const File &f, StringRef secName) - : VeneerAtom(f, secName) {} - - ArrayRef<uint8_t> rawContent() const override { - return llvm::makeArrayRef(Veneer_THM_B_BL_Abs_a_AtomContent); - } -}; - -template <DefinedAtom::CodeModel Model> -class ARMVeneerMappingAtom : public VeneerAtom { -public: - ARMVeneerMappingAtom(const File &f, StringRef secName, StringRef name) - : VeneerAtom(f, secName, getMappingAtomName(Model, name)) { - static_assert((Model == DefinedAtom::codeARM_a || - Model == DefinedAtom::codeARM_d || - Model == DefinedAtom::codeARM_t), - "Only mapping atom types are allowed"); - } - - uint64_t size() const override { return 0; } - - ArrayRef<uint8_t> rawContent() const override { return ArrayRef<uint8_t>(); } - - DefinedAtom::CodeModel codeModel() const override { return Model; } -}; - -template <class BaseAtom, DefinedAtom::CodeModel Model> -class BaseMappingAtom : public BaseAtom { -public: - BaseMappingAtom(const File &f, StringRef secName, StringRef name) - : BaseAtom(f, secName) { - static_assert((Model == DefinedAtom::codeARM_a || - Model == DefinedAtom::codeARM_d || - Model == DefinedAtom::codeARM_t), - "Only mapping atom types are allowed"); -#ifndef NDEBUG - _name = name; -#else - _name = getMappingAtomName(Model, name); -#endif - } - - DefinedAtom::CodeModel codeModel() const override { -#ifndef NDEBUG - return isThumbCode(Model) ? DefinedAtom::codeARMThumb : DefinedAtom::codeNA; -#else - return Model; -#endif - } - - StringRef name() const override { return _name; } - -private: - std::string _name; -}; - -/// \brief Atoms that are used by ARM dynamic linking -class ARMGOTAtom : public GOTAtom { -public: - ARMGOTAtom(const File &f) : GOTAtom(f, ".got") {} - - ArrayRef<uint8_t> rawContent() const override { - return llvm::makeArrayRef(ARMGotAtomContent); - } - - Alignment alignment() const override { return 4; } - -protected: - // Constructor for PLTGOT atom. - ARMGOTAtom(const File &f, StringRef secName) : GOTAtom(f, secName) {} -}; - -class ARMGOTPLTAtom : public ARMGOTAtom { -public: - ARMGOTPLTAtom(const File &f) : ARMGOTAtom(f, ".got.plt") {} -}; - -/// \brief Proxy class to keep type compatibility with PLT0Atom. -class ARMPLT0Atom : public PLT0Atom { -public: - ARMPLT0Atom(const File &f, StringRef) : PLT0Atom(f) {} -}; - -/// \brief PLT0 entry atom. -/// Serves as a mapping symbol in the release mode. -class ARMPLT0_a_Atom - : public BaseMappingAtom<ARMPLT0Atom, DefinedAtom::codeARM_a> { -public: - ARMPLT0_a_Atom(const File &f, const std::string &name) - : BaseMappingAtom(f, ".plt", name) {} - - ArrayRef<uint8_t> rawContent() const override { - return llvm::makeArrayRef(ARMPlt0_a_AtomContent); - } - - Alignment alignment() const override { return 4; } -}; - -class ARMPLT0_d_Atom - : public BaseMappingAtom<ARMPLT0Atom, DefinedAtom::codeARM_d> { -public: - ARMPLT0_d_Atom(const File &f, const std::string &name) - : BaseMappingAtom(f, ".plt", name) {} - - ArrayRef<uint8_t> rawContent() const override { - return llvm::makeArrayRef(ARMPlt0_d_AtomContent); - } - - Alignment alignment() const override { return 4; } -}; - -/// \brief PLT entry atom. -/// Serves as a mapping symbol in the release mode. -class ARMPLTAtom : public BaseMappingAtom<PLTAtom, DefinedAtom::codeARM_a> { -public: - ARMPLTAtom(const File &f, const std::string &name) - : BaseMappingAtom(f, ".plt", name) {} - - ArrayRef<uint8_t> rawContent() const override { - return llvm::makeArrayRef(ARMPltAtomContent); - } - - Alignment alignment() const override { return 4; } -}; - -/// \brief Veneer atom for PLT entry. -/// Serves as a mapping symbol in the release mode. -class ARMPLTVeneerAtom - : public BaseMappingAtom<PLTAtom, DefinedAtom::codeARM_t> { -public: - ARMPLTVeneerAtom(const File &f, const std::string &name) - : BaseMappingAtom(f, ".plt", name) {} - - ArrayRef<uint8_t> rawContent() const override { - return llvm::makeArrayRef(ARMPltVeneerAtomContent); - } - - Alignment alignment() const override { return 4; } -}; - -/// \brief Atom which represents an object for which a COPY relocation will -/// be generated. -class ARMObjectAtom : public ObjectAtom { -public: - ARMObjectAtom(const File &f) : ObjectAtom(f) {} - Alignment alignment() const override { return 4; } -}; - -class ELFPassFile : public SimpleFile { -public: - ELFPassFile(const ELFLinkingContext &eti) - : SimpleFile("ELFPassFile", kindELFObject) { - setOrdinal(eti.getNextOrdinalAndIncrement()); - } - - llvm::BumpPtrAllocator _alloc; -}; - -/// \brief CRTP base for handling relocations. -template <class Derived> class ARMRelocationPass : public Pass { - /// \brief Handle a specific reference. - void handleReference(const DefinedAtom &atom, const Reference &ref) { - DEBUG_WITH_TYPE( - "ARM", 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::ARM); - switch (ref.kindValue()) { - case R_ARM_ABS32: - case R_ARM_REL32: - case R_ARM_TARGET1: - case R_ARM_MOVW_ABS_NC: - case R_ARM_MOVT_ABS: - case R_ARM_THM_MOVW_ABS_NC: - case R_ARM_THM_MOVT_ABS: - static_cast<Derived *>(this)->handlePlain(isThumbCode(&atom), ref); - break; - case R_ARM_THM_CALL: - case R_ARM_CALL: - case R_ARM_JUMP24: - case R_ARM_THM_JUMP24: - case R_ARM_THM_JUMP11: { - const auto actualModel = actualSourceCodeModel(atom, ref); - const bool fromThumb = isThumbCode(actualModel); - static_cast<Derived *>(this)->handlePlain(fromThumb, ref); - static_cast<Derived *>(this)->handleVeneer(atom, fromThumb, ref); - } break; - case R_ARM_TLS_IE32: - static_cast<Derived *>(this)->handleTLSIE32(ref); - break; - case R_ARM_GOT_BREL: - static_cast<Derived *>(this)->handleGOT(ref); - break; - default: - break; - } - } - -protected: - /// \brief Determine source atom's actual code model. - /// - /// Actual code model may differ from the existing one if fixup - /// is possible on the later stages for given relocation type. - DefinedAtom::CodeModel actualSourceCodeModel(const DefinedAtom &atom, - const Reference &ref) { - const auto kindValue = ref.kindValue(); - if (kindValue != R_ARM_CALL && kindValue != R_ARM_THM_CALL) - return atom.codeModel(); - - // TODO: For unconditional jump instructions (R_ARM_CALL and R_ARM_THM_CALL) - // fixup isn't possible without veneer generation for archs below ARMv5. - - auto actualModel = atom.codeModel(); - if (const auto *da = dyn_cast<DefinedAtom>(ref.target())) { - actualModel = da->codeModel(); - } else if (const auto *sla = dyn_cast<SharedLibraryAtom>(ref.target())) { - if (sla->type() == SharedLibraryAtom::Type::Code) { - // PLT entry will be generated here - assume we don't want a veneer - // on top of it and prefer instruction fixup if needed. - actualModel = DefinedAtom::codeNA; - } - } - return actualModel; - } - - std::error_code handleVeneer(const DefinedAtom &atom, bool fromThumb, - const Reference &ref) { - // Actual instruction mode differs meaning that further fixup will be - // applied. - if (isThumbCode(&atom) != fromThumb) - return std::error_code(); - - const VeneerAtom *(Derived::*getVeneer)(const DefinedAtom *, StringRef) = - nullptr; - const auto kindValue = ref.kindValue(); - switch (kindValue) { - case R_ARM_JUMP24: - getVeneer = &Derived::getVeneer_ARM_B_BL; - break; - case R_ARM_THM_JUMP24: - getVeneer = &Derived::getVeneer_THM_B_BL; - break; - default: - return std::error_code(); - } - - // Target symbol and relocated place should have different - // instruction sets in order a veneer to be generated in between. - const auto *target = dyn_cast<DefinedAtom>(ref.target()); - if (!target || isThumbCode(target) == isThumbCode(&atom)) - return std::error_code(); - - // Veneers may only be generated for STT_FUNC target symbols - // or for symbols located in sections different to the place of relocation. - StringRef secName = atom.customSectionName(); - if (DefinedAtom::typeCode != target->contentType() && - !target->customSectionName().equals(secName)) { - StringRef kindValStr; - if (!this->_ctx.registry().referenceKindToString( - ref.kindNamespace(), ref.kindArch(), kindValue, kindValStr)) { - kindValStr = "unknown"; - } - - std::string errStr = - (Twine("Reference of type ") + Twine(kindValue) + " (" + kindValStr + - ") from " + atom.name() + "+" + Twine(ref.offsetInAtom()) + " to " + - ref.target()->name() + "+" + Twine(ref.addend()) + - " cannot be effected without a veneer").str(); - - llvm_unreachable(errStr.c_str()); - } - - assert(getVeneer && "The veneer handler is missing"); - const Atom *veneer = - (static_cast<Derived *>(this)->*getVeneer)(target, secName); - - assert(veneer && "The veneer is not set"); - const_cast<Reference &>(ref).setTarget(veneer); - return std::error_code(); - } - - /// \brief Get the veneer for ARM B/BL instructions - /// in absolute code. - const VeneerAtom *getVeneer_ARM_B_BL_Abs(const DefinedAtom *da, - StringRef secName) { - auto veneer = _veneerAtoms.lookup(da); - if (!veneer.empty()) - return veneer._veneer; - - std::string name = "__"; - name += da->name(); - name += "_from_arm"; - // Create parts of veneer with mapping symbols. - auto v_a = - new (_file._alloc) Veneer_ARM_B_BL_Abs_a_Atom(_file, secName, name); - addVeneerWithMapping<DefinedAtom::codeARM_a>(da, v_a, name); - auto v_d = new (_file._alloc) Veneer_ARM_B_BL_Abs_d_Atom(_file, secName); - addVeneerWithMapping<DefinedAtom::codeARM_d>(v_a, v_d, name); - - // Fake reference to show connection between parts of veneer. - v_a->addReferenceELF_ARM(R_ARM_NONE, 0, v_d, 0); - // Real reference to fixup. - v_d->addReferenceELF_ARM(R_ARM_ABS32, 0, da, 0); - return v_a; - } - - /// \brief Get the veneer for Thumb B/BL instructions - /// in absolute code. - const VeneerAtom *getVeneer_THM_B_BL_Abs(const DefinedAtom *da, - StringRef secName) { - auto veneer = _veneerAtoms.lookup(da); - if (!veneer.empty()) - return veneer._veneer; - - std::string name = "__"; - name += da->name(); - name += "_from_thumb"; - // Create parts of veneer with mapping symbols. - auto v_t = - new (_file._alloc) Veneer_THM_B_BL_Abs_t_Atom(_file, secName, name); - addVeneerWithMapping<DefinedAtom::codeARM_t>(da, v_t, name); - auto v_a = new (_file._alloc) Veneer_THM_B_BL_Abs_a_Atom(_file, secName); - addVeneerWithMapping<DefinedAtom::codeARM_a>(v_t, v_a, name); - - // Fake reference to show connection between parts of veneer. - v_t->addReferenceELF_ARM(R_ARM_NONE, 0, v_a, 0); - // Real reference to fixup. - v_a->addReferenceELF_ARM(R_ARM_JUMP24, 0, da, 0); - return v_t; - } - - std::error_code handleTLSIE32(const Reference &ref) { - if (const auto *target = dyn_cast<DefinedAtom>(ref.target())) { - const_cast<Reference &>(ref) - .setTarget(static_cast<Derived *>(this)->getTLSTPOFF32(target)); - return std::error_code(); - } - llvm_unreachable("R_ARM_TLS_IE32 reloc targets wrong atom type"); - } - - /// \brief Create a GOT entry for TLS with reloc type and addend specified. - template <Reference::KindValue R_ARM_TLS, Reference::Addend A = 0> - const GOTAtom *getGOTTLSEntry(const DefinedAtom *da) { - StringRef source; -#ifndef NDEBUG - source = "_tls_"; -#endif - return getGOT<R_ARM_TLS, A>(da, source); - } - - /// \brief Add veneer with mapping symbol. - template <DefinedAtom::CodeModel Model> - void addVeneerWithMapping(const DefinedAtom *da, VeneerAtom *va, - const std::string &name) { - assert(_veneerAtoms.lookup(da).empty() && - "Veneer or mapping already exists"); - auto *ma = new (_file._alloc) - ARMVeneerMappingAtom<Model>(_file, va->customSectionName(), name); - - // Fake reference to show connection between the mapping symbol and veneer. - va->addReferenceELF_ARM(R_ARM_NONE, 0, ma, 0); - _veneerAtoms[da] = VeneerWithMapping(va, ma); - } - - /// \brief get a veneer for a PLT entry. - const PLTAtom *getPLTVeneer(const Atom *da, PLTAtom *pa, StringRef source) { - std::string name = "__plt_from_thumb"; - name += source.empty() ? "_" : source; - name += da->name(); - // Create veneer for PLT entry. - auto va = new (_file._alloc) ARMPLTVeneerAtom(_file, name); - // Fake reference to show connection between veneer and PLT entry. - va->addReferenceELF_ARM(R_ARM_NONE, 0, pa, 0); - - _pltAtoms[da] = PLTWithVeneer(pa, va); - return va; - } - - typedef const GOTAtom *(Derived::*GOTFactory)(const Atom *); - - /// \brief get a PLT entry referencing PLTGOT entry. - /// - /// If the entry does not exist, both GOT and PLT entry are created. - const PLTAtom *getPLT(const Atom *da, bool fromThumb, GOTFactory gotFactory, - StringRef source = "") { - auto pltVeneer = _pltAtoms.lookup(da); - if (!pltVeneer.empty()) { - // Return clean PLT entry provided it is ARM code. - if (!fromThumb) - return pltVeneer._plt; - - // Check if veneer is present for Thumb to ARM transition. - if (pltVeneer._veneer) - return pltVeneer._veneer; - - // Create veneer for existing PLT entry. - return getPLTVeneer(da, pltVeneer._plt, source); - } - - // Create specific GOT entry. - const auto *ga = (static_cast<Derived *>(this)->*gotFactory)(da); - assert(_gotpltAtoms.lookup(da) == ga && - "GOT entry should be added to the PLTGOT map"); - assert(ga->customSectionName() == ".got.plt" && - "GOT entry should be in a special section"); - - std::string name = "__plt"; - name += source.empty() ? "_" : source; - name += da->name(); - // Create PLT entry for the GOT entry. - auto pa = new (_file._alloc) ARMPLTAtom(_file, name); - pa->addReferenceELF_ARM(R_ARM_ALU_PC_G0_NC, 0, ga, -8); - pa->addReferenceELF_ARM(R_ARM_ALU_PC_G1_NC, 4, ga, -4); - pa->addReferenceELF_ARM(R_ARM_LDR_PC_G2, 8, ga, 0); - - // Since all PLT entries are in ARM code, Thumb to ARM - // switching should be added if the relocated place contais Thumb code. - if (fromThumb) - return getPLTVeneer(da, pa, source); - - // Otherwise just add PLT entry and return it to the caller. - _pltAtoms[da] = PLTWithVeneer(pa); - return pa; - } - - /// \brief Create the GOT entry for a given IFUNC Atom. - const GOTAtom *createIFUNCGOT(const Atom *da) { - assert(!_gotpltAtoms.lookup(da) && "IFUNC GOT entry already exists"); - auto g = new (_file._alloc) ARMGOTPLTAtom(_file); - g->addReferenceELF_ARM(R_ARM_ABS32, 0, da, 0); - g->addReferenceELF_ARM(R_ARM_IRELATIVE, 0, da, 0); -#ifndef NDEBUG - g->_name = "__got_ifunc_"; - g->_name += da->name(); -#endif - _gotpltAtoms[da] = g; - return g; - } - - /// \brief get the PLT entry for a given IFUNC Atom. - const PLTAtom *getIFUNCPLTEntry(const DefinedAtom *da, bool fromThumb) { - return getPLT(da, fromThumb, &Derived::createIFUNCGOT, "_ifunc_"); - } - - /// \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(bool fromThumb, const Reference &ref) { - auto target = dyn_cast<const DefinedAtom>(ref.target()); - if (target && target->contentType() == DefinedAtom::typeResolver) { - const_cast<Reference &>(ref) - .setTarget(getIFUNCPLTEntry(target, fromThumb)); - } - return std::error_code(); - } - - /// \brief Create a GOT entry containing 0. - const GOTAtom *getNullGOT() { - if (!_null) { - _null = new (_file._alloc) ARMGOTPLTAtom(_file); -#ifndef NDEBUG - _null->_name = "__got_null"; -#endif - } - return _null; - } - - /// \brief Create regular GOT entry which cannot be used in PLTGOT operation. - template <Reference::KindValue R_ARM_REL, Reference::Addend A = 0> - const GOTAtom *getGOT(const Atom *da, StringRef source = "") { - if (auto got = _gotAtoms.lookup(da)) - return got; - auto g = new (_file._alloc) ARMGOTAtom(_file); - g->addReferenceELF_ARM(R_ARM_REL, 0, da, A); -#ifndef NDEBUG - g->_name = "__got"; - g->_name += source.empty() ? "_" : source; - g->_name += da->name(); -#endif - _gotAtoms[da] = g; - return g; - } - - /// \brief get GOT entry for a regular defined atom. - const GOTAtom *getGOTEntry(const DefinedAtom *da) { - return getGOT<R_ARM_ABS32>(da); - } - - std::error_code handleGOT(const Reference &ref) { - if (isa<UndefinedAtom>(ref.target())) - const_cast<Reference &>(ref).setTarget(getNullGOT()); - else if (const auto *da = dyn_cast<DefinedAtom>(ref.target())) - const_cast<Reference &>(ref).setTarget(getGOTEntry(da)); - return std::error_code(); - } - -public: - ARMRelocationPass(const ELFLinkingContext &ctx) : _file(ctx), _ctx(ctx) {} - - /// \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. - std::error_code perform(SimpleFile &mf) override { - ScopedTask task(getDefaultDomain(), "ARM GOT/PLT Pass"); - DEBUG_WITH_TYPE( - "ARM", 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"; - } - - llvm::dbgs() << "Defined Atoms" << "\n"; - for (const auto &atom - : mf.defined()) { - llvm::dbgs() << " Name of Atom: " << atom->name().str() << "\n"; - }); - - // Process all references. - 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); - _plt0_d->setOrdinal(ordinal++); - mf.addAtom(*_plt0_d); - } - for (auto &pltKV : _pltAtoms) { - auto &plt = pltKV.second; - if (auto *v = plt._veneer) { - v->setOrdinal(ordinal++); - mf.addAtom(*v); - } - auto *p = plt._plt; - p->setOrdinal(ordinal++); - mf.addAtom(*p); - } - if (_null) { - _null->setOrdinal(ordinal++); - mf.addAtom(*_null); - } - if (_plt0) { - _got0->setOrdinal(ordinal++); - mf.addAtom(*_got0); - _got1->setOrdinal(ordinal++); - mf.addAtom(*_got1); - } - for (auto &gotKV : _gotAtoms) { - auto &got = gotKV.second; - got->setOrdinal(ordinal++); - mf.addAtom(*got); - } - for (auto &gotKV : _gotpltAtoms) { - auto &got = gotKV.second; - got->setOrdinal(ordinal++); - mf.addAtom(*got); - } - for (auto &objectKV : _objectAtoms) { - auto &obj = objectKV.second; - obj->setOrdinal(ordinal++); - mf.addAtom(*obj); - } - for (auto &veneerKV : _veneerAtoms) { - auto &veneer = veneerKV.second; - auto *m = veneer._mapping; - m->setOrdinal(ordinal++); - mf.addAtom(*m); - auto *v = veneer._veneer; - v->setOrdinal(ordinal++); - mf.addAtom(*v); - } - - return std::error_code(); - } - -protected: - /// \brief Owner of all the Atoms created by this pass. - ELFPassFile _file; - const ELFLinkingContext &_ctx; - - /// \brief Map Atoms to their GOT entries. - llvm::MapVector<const Atom *, GOTAtom *> _gotAtoms; - - /// \brief Map Atoms to their PLTGOT entries. - llvm::MapVector<const Atom *, GOTAtom *> _gotpltAtoms; - - /// \brief Map Atoms to their Object entries. - llvm::MapVector<const Atom *, ObjectAtom *> _objectAtoms; - - /// \brief Map Atoms to their PLT entries depending on the code model. - struct PLTWithVeneer { - PLTWithVeneer(PLTAtom *p = nullptr, PLTAtom *v = nullptr) - : _plt(p), _veneer(v) {} - - bool empty() const { - assert((_plt || !_veneer) && "Veneer appears without PLT entry"); - return !_plt && !_veneer; - } - - PLTAtom *_plt; - PLTAtom *_veneer; - }; - llvm::MapVector<const Atom *, PLTWithVeneer> _pltAtoms; - - /// \brief Map Atoms to their veneers. - struct VeneerWithMapping { - VeneerWithMapping(VeneerAtom *v = nullptr, VeneerAtom *m = nullptr) - : _veneer(v), _mapping(m) {} - - bool empty() const { - assert(((bool)_veneer == (bool)_mapping) && - "Mapping symbol should always be paired with veneer"); - return !_veneer && !_mapping; - } - - VeneerAtom *_veneer; - VeneerAtom *_mapping; - }; - llvm::MapVector<const Atom *, VeneerWithMapping> _veneerAtoms; - - /// \brief GOT entry that is always 0. Used for undefined weaks. - GOTAtom *_null = nullptr; - - /// \brief The got and plt entries for .PLT0. This is used to call into the - /// dynamic linker for symbol resolution. - /// @{ - PLT0Atom *_plt0 = nullptr; - PLT0Atom *_plt0_d = nullptr; - GOTAtom *_got0 = nullptr; - GOTAtom *_got1 = nullptr; - /// @} -}; - -/// 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 ARMStaticRelocationPass final - : public ARMRelocationPass<ARMStaticRelocationPass> { -public: - ARMStaticRelocationPass(const elf::ARMLinkingContext &ctx) - : ARMRelocationPass(ctx) {} - - /// \brief Handle ordinary relocation references. - std::error_code handlePlain(bool fromThumb, const Reference &ref) { - return handleIFUNC(fromThumb, ref); - } - - /// \brief Get the veneer for ARM B/BL instructions. - const VeneerAtom *getVeneer_ARM_B_BL(const DefinedAtom *da, - StringRef secName) { - return getVeneer_ARM_B_BL_Abs(da, secName); - } - - /// \brief Get the veneer for Thumb B/BL instructions. - const VeneerAtom *getVeneer_THM_B_BL(const DefinedAtom *da, - StringRef secName) { - return getVeneer_THM_B_BL_Abs(da, secName); - } - - /// \brief Create a GOT entry for R_ARM_TLS_TPOFF32 reloc. - const GOTAtom *getTLSTPOFF32(const DefinedAtom *da) { - return getGOTTLSEntry<R_ARM_TLS_LE32>(da); - } -}; - -/// This implements the dynamic relocation model. GOT and PLT entries are -/// created for references that cannot be directly resolved. -class ARMDynamicRelocationPass final - : public ARMRelocationPass<ARMDynamicRelocationPass> { -public: - ARMDynamicRelocationPass(const elf::ARMLinkingContext &ctx) - : ARMRelocationPass(ctx) {} - - /// \brief get the PLT entry for a given atom. - const PLTAtom *getPLTEntry(const SharedLibraryAtom *sla, bool fromThumb) { - return getPLT(sla, fromThumb, &ARMDynamicRelocationPass::createPLTGOT); - } - - /// \brief Create the GOT entry for a given atom. - const GOTAtom *createPLTGOT(const Atom *da) { - assert(!_gotpltAtoms.lookup(da) && "PLTGOT entry already exists"); - auto g = new (_file._alloc) ARMGOTPLTAtom(_file); - g->addReferenceELF_ARM(R_ARM_ABS32, 0, getPLT0(), 0); - g->addReferenceELF_ARM(R_ARM_JUMP_SLOT, 0, da, 0); -#ifndef NDEBUG - g->_name = "__got_plt0_"; - g->_name += da->name(); -#endif - _gotpltAtoms[da] = g; - return g; - } - - const ObjectAtom *getObjectEntry(const SharedLibraryAtom *a) { - if (auto obj = _objectAtoms.lookup(a)) - return obj; - - auto oa = new (_file._alloc) ARMObjectAtom(_file); - oa->addReferenceELF_ARM(R_ARM_COPY, 0, oa, 0); - - oa->_name = a->name(); - oa->_size = a->size(); - - _objectAtoms[a] = oa; - return oa; - } - - /// \brief Handle ordinary relocation references. - std::error_code handlePlain(bool fromThumb, const Reference &ref) { - if (auto sla = dyn_cast<SharedLibraryAtom>(ref.target())) { - if (sla->type() == SharedLibraryAtom::Type::Data && - _ctx.getOutputELFType() == llvm::ELF::ET_EXEC) { - const_cast<Reference &>(ref).setTarget(getObjectEntry(sla)); - } else if (sla->type() == SharedLibraryAtom::Type::Code) { - const_cast<Reference &>(ref).setTarget(getPLTEntry(sla, fromThumb)); - } - return std::error_code(); - } - return handleIFUNC(fromThumb, ref); - } - - /// \brief Get the veneer for ARM B/BL instructions. - const VeneerAtom *getVeneer_ARM_B_BL(const DefinedAtom *da, - StringRef secName) { - if (_ctx.getOutputELFType() == llvm::ELF::ET_EXEC) { - return getVeneer_ARM_B_BL_Abs(da, secName); - } - llvm_unreachable("Handle ARM veneer for DSOs"); - } - - /// \brief Get the veneer for Thumb B/BL instructions. - const VeneerAtom *getVeneer_THM_B_BL(const DefinedAtom *da, - StringRef secName) { - if (_ctx.getOutputELFType() == llvm::ELF::ET_EXEC) { - return getVeneer_THM_B_BL_Abs(da, secName); - } - llvm_unreachable("Handle Thumb veneer for DSOs"); - } - - /// \brief Create a GOT entry for R_ARM_TLS_TPOFF32 reloc. - const GOTAtom *getTLSTPOFF32(const DefinedAtom *da) { - return getGOTTLSEntry<R_ARM_TLS_TPOFF32>(da); - } - - const PLT0Atom *getPLT0() { - if (_plt0) - return _plt0; - // Fill in the null entry. - getNullGOT(); - _plt0 = new (_file._alloc) ARMPLT0_a_Atom(_file, "__PLT0"); - _plt0_d = new (_file._alloc) ARMPLT0_d_Atom(_file, "__PLT0_d"); - _got0 = new (_file._alloc) ARMGOTPLTAtom(_file); - _got1 = new (_file._alloc) ARMGOTPLTAtom(_file); - _plt0_d->addReferenceELF_ARM(R_ARM_REL32, 0, _got1, 0); - // Fake reference to show connection between the GOT and PLT entries. - _plt0->addReferenceELF_ARM(R_ARM_NONE, 0, _got0, 0); - // Fake reference to show connection between parts of PLT entry. - _plt0->addReferenceELF_ARM(R_ARM_NONE, 0, _plt0_d, 0); -#ifndef NDEBUG - _got0->_name = "__got0"; - _got1->_name = "__got1"; -#endif - return _plt0; - } - - const GOTAtom *getSharedGOTEntry(const SharedLibraryAtom *sla) { - return getGOT<R_ARM_GLOB_DAT>(sla); - } - - std::error_code handleGOT(const Reference &ref) { - if (const auto sla = dyn_cast<const SharedLibraryAtom>(ref.target())) { - const_cast<Reference &>(ref).setTarget(getSharedGOTEntry(sla)); - return std::error_code(); - } - return ARMRelocationPass::handleGOT(ref); - } -}; - -} // end of anon namespace - -std::unique_ptr<Pass> -lld::elf::createARMRelocationPass(const ARMLinkingContext &ctx) { - switch (ctx.getOutputELFType()) { - case llvm::ELF::ET_EXEC: - if (ctx.isDynamic()) - return llvm::make_unique<ARMDynamicRelocationPass>(ctx); - return llvm::make_unique<ARMStaticRelocationPass>(ctx); - case llvm::ELF::ET_DYN: - return llvm::make_unique<ARMDynamicRelocationPass>(ctx); - default: - llvm_unreachable("Unhandled output file type"); - } -} |
