[ARM] Add mapping symbols to veneers
This required splitting up veneer atoms into pieces, where every piece is paired with mapping atom of the corresponding type. llvm-svn: 234473
This commit is contained in:
Denis Protivensky
parent
2aa8c8fd17
commit
6b3a33ff00
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@ -32,17 +32,21 @@ namespace {
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// ARM B/BL instructions of static relocation veneer.
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// TODO: consider different instruction set for archs below ARMv5
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// (one as for Thumb may be used though it's less optimal).
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static const uint8_t Veneer_ARM_B_BL_StaticAtomContent[8] = {
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0x04, 0xf0, 0x1f, 0xe5, // ldr pc, [pc, #-4]
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static const uint8_t Veneer_ARM_B_BL_Static_a_AtomContent[4] = {
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0x04, 0xf0, 0x1f, 0xe5 // ldr pc, [pc, #-4]
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};
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static const uint8_t Veneer_ARM_B_BL_Static_d_AtomContent[4] = {
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0x00, 0x00, 0x00, 0x00 // <target_symbol_address>
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};
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// Thumb B/BL instructions of static relocation veneer.
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// TODO: consider different instruction set for archs above ARMv5
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// (one as for ARM may be used since it's more optimal).
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static const uint8_t Veneer_THM_B_BL_StaticAtomContent[8] = {
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static const uint8_t Veneer_THM_B_BL_Static_t_AtomContent[4] = {
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0x78, 0x47, // bx pc
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0x00, 0x00, // nop
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0x00, 0x00 // nop
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};
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static const uint8_t Veneer_THM_B_BL_Static_a_AtomContent[4] = {
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0xfe, 0xff, 0xff, 0xea // b <target_symbol_address>
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};
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@ -62,7 +66,6 @@ static const uint8_t ARMPltVeneerAtomContent[4] = {
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0x00, 0x00 // nop
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};
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#ifdef NDEBUG
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// Determine proper names for mapping symbols.
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static std::string getMappingAtomName(DefinedAtom::CodeModel model,
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const std::string &part) {
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@ -77,15 +80,14 @@ static std::string getMappingAtomName(DefinedAtom::CodeModel model,
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llvm_unreachable("Wrong code model of mapping atom");
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}
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}
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#endif
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/// \brief Atoms that hold veneer code.
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class VeneerAtom : public SimpleELFDefinedAtom {
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StringRef _section;
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public:
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VeneerAtom(const File &f, StringRef secName)
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: SimpleELFDefinedAtom(f), _section(secName) {}
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VeneerAtom(const File &f, StringRef secName, const std::string &name = "")
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: SimpleELFDefinedAtom(f), _section(secName), _name(name) {}
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Scope scope() const override { return DefinedAtom::scopeTranslationUnit; }
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@ -106,37 +108,79 @@ public:
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Alignment alignment() const override { return 4; }
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StringRef name() const override { return _name; }
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private:
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std::string _name;
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};
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/// \brief Atoms that hold veneer for statically relocated
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/// ARM B/BL instructions.
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class Veneer_ARM_B_BL_StaticAtom : public VeneerAtom {
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class Veneer_ARM_B_BL_Static_a_Atom : public VeneerAtom {
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public:
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Veneer_ARM_B_BL_StaticAtom(const File &f, StringRef secName)
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Veneer_ARM_B_BL_Static_a_Atom(const File &f, StringRef secName,
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const std::string &name)
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: VeneerAtom(f, secName, name) {}
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ArrayRef<uint8_t> rawContent() const override {
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return llvm::makeArrayRef(Veneer_ARM_B_BL_Static_a_AtomContent);
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}
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};
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class Veneer_ARM_B_BL_Static_d_Atom : public VeneerAtom {
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public:
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Veneer_ARM_B_BL_Static_d_Atom(const File &f, StringRef secName)
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: VeneerAtom(f, secName) {}
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ArrayRef<uint8_t> rawContent() const override {
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return llvm::makeArrayRef(Veneer_ARM_B_BL_StaticAtomContent);
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return llvm::makeArrayRef(Veneer_ARM_B_BL_Static_d_AtomContent);
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}
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};
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/// \brief Atoms that hold veneer for statically relocated
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/// Thumb B/BL instructions.
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class Veneer_THM_B_BL_StaticAtom : public VeneerAtom {
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class Veneer_THM_B_BL_Static_t_Atom : public VeneerAtom {
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public:
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Veneer_THM_B_BL_StaticAtom(const File &f, StringRef secName)
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: VeneerAtom(f, secName) {}
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Veneer_THM_B_BL_Static_t_Atom(const File &f, StringRef secName,
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const std::string &name)
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: VeneerAtom(f, secName, name) {}
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DefinedAtom::CodeModel codeModel() const override {
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return DefinedAtom::codeARMThumb;
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}
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ArrayRef<uint8_t> rawContent() const override {
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return llvm::makeArrayRef(Veneer_THM_B_BL_StaticAtomContent);
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return llvm::makeArrayRef(Veneer_THM_B_BL_Static_t_AtomContent);
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}
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};
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class Veneer_THM_B_BL_Static_a_Atom : public VeneerAtom {
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public:
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Veneer_THM_B_BL_Static_a_Atom(const File &f, StringRef secName)
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: VeneerAtom(f, secName) {}
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ArrayRef<uint8_t> rawContent() const override {
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return llvm::makeArrayRef(Veneer_THM_B_BL_Static_a_AtomContent);
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}
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};
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template <DefinedAtom::CodeModel Model>
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class ARMVeneerMappingAtom : public VeneerAtom {
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public:
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ARMVeneerMappingAtom(const File &f, StringRef secName, StringRef name)
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: VeneerAtom(f, secName, getMappingAtomName(Model, name)) {
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static_assert((Model == DefinedAtom::codeARM_a ||
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Model == DefinedAtom::codeARM_d ||
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Model == DefinedAtom::codeARM_t),
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"Only mapping atom types are allowed");
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}
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uint64_t size() const override { return 0; }
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ArrayRef<uint8_t> rawContent() const override { return ArrayRef<uint8_t>(); }
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DefinedAtom::CodeModel codeModel() const override { return Model; }
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};
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/// \brief Atoms that are used by ARM dynamic linking
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class ARMGOTAtom : public GOTAtom {
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public:
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@ -353,6 +397,20 @@ protected:
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return g;
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}
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/// \brief Add veneer with mapping symbol.
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template <DefinedAtom::CodeModel Model>
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void addVeneerWithMapping(const DefinedAtom *da, VeneerAtom *va,
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const std::string &name) {
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assert(_veneerAtoms.lookup(da).empty() &&
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"Veneer or mapping already exists");
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auto *ma = new (_file._alloc)
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ARMVeneerMappingAtom<Model>(_file, va->customSectionName(), name);
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// Fake reference to show connection between the mapping symbol and veneer.
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va->addReferenceELF_ARM(R_ARM_NONE, 0, ma, 0);
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_veneerAtoms[da] = VeneerWithMapping(va, ma);
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}
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/// \brief get a veneer for a PLT entry.
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const PLTAtom *getPLTVeneer(const DefinedAtom *da, PLTAtom *pa,
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StringRef source) {
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@ -539,8 +597,12 @@ public:
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}
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for (auto &veneerKV : _veneerAtoms) {
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auto &veneer = veneerKV.second;
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veneer->setOrdinal(ordinal++);
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mf->addAtom(*veneer);
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auto *m = veneer._mapping;
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m->setOrdinal(ordinal++);
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mf->addAtom(*m);
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auto *v = veneer._veneer;
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v->setOrdinal(ordinal++);
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mf->addAtom(*v);
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}
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}
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@ -568,7 +630,20 @@ protected:
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llvm::MapVector<const Atom *, PLTWithVeneer> _pltAtoms;
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/// \brief Map Atoms to their veneers.
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llvm::MapVector<const Atom *, VeneerAtom *> _veneerAtoms;
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struct VeneerWithMapping {
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VeneerWithMapping(VeneerAtom *v = nullptr, VeneerAtom *m = nullptr)
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: _veneer(v), _mapping(m) {}
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bool empty() const {
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assert(((bool)_veneer == (bool)_mapping) &&
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"Mapping symbol should always be paired with veneer");
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return !_veneer && !_mapping;
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}
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VeneerAtom *_veneer;
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VeneerAtom *_mapping;
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};
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llvm::MapVector<const Atom *, VeneerWithMapping> _veneerAtoms;
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/// \brief GOT entry that is always 0. Used for undefined weaks.
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GOTAtom *_null = nullptr;
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@ -589,33 +664,47 @@ public:
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/// \brief Get the veneer for ARM B/BL instructions.
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const VeneerAtom *getVeneer_ARM_B_BL(const DefinedAtom *da,
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StringRef secName) {
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if (auto veneer = _veneerAtoms.lookup(da))
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return veneer;
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auto v = new (_file._alloc) Veneer_ARM_B_BL_StaticAtom(_file, secName);
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v->addReferenceELF_ARM(R_ARM_ABS32, 4, da, 0);
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auto veneer = _veneerAtoms.lookup(da);
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if (!veneer.empty())
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return veneer._veneer;
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v->_name = "__";
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v->_name += da->name();
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v->_name += "_from_arm";
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std::string name = "__";
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name += da->name();
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name += "_from_arm";
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// Create parts of veneer with mapping symbols.
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auto v_a = new (_file._alloc) Veneer_ARM_B_BL_Static_a_Atom(_file, secName, name);
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addVeneerWithMapping<DefinedAtom::codeARM_a>(da, v_a, name);
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auto v_d = new (_file._alloc) Veneer_ARM_B_BL_Static_d_Atom(_file, secName);
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addVeneerWithMapping<DefinedAtom::codeARM_d>(v_a, v_d, name);
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_veneerAtoms[da] = v;
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return v;
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// Fake reference to show connection between parts of veneer.
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v_a->addReferenceELF_ARM(R_ARM_NONE, 0, v_d, 0);
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// Real reference to fixup.
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v_d->addReferenceELF_ARM(R_ARM_ABS32, 0, da, 0);
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return v_a;
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}
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/// \brief Get the veneer for Thumb B/BL instructions.
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const VeneerAtom *getVeneer_THM_B_BL(const DefinedAtom *da,
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StringRef secName) {
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if (auto veneer = _veneerAtoms.lookup(da))
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return veneer;
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auto v = new (_file._alloc) Veneer_THM_B_BL_StaticAtom(_file, secName);
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v->addReferenceELF_ARM(R_ARM_JUMP24, 4, da, 0);
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auto veneer = _veneerAtoms.lookup(da);
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if (!veneer.empty())
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return veneer._veneer;
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v->_name = "__";
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v->_name += da->name();
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v->_name += "_from_thumb";
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std::string name = "__";
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name += da->name();
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name += "_from_thumb";
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// Create parts of veneer with mapping symbols.
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auto v_t = new (_file._alloc) Veneer_THM_B_BL_Static_t_Atom(_file, secName, name);
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addVeneerWithMapping<DefinedAtom::codeARM_t>(da, v_t, name);
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auto v_a = new (_file._alloc) Veneer_THM_B_BL_Static_a_Atom(_file, secName);
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addVeneerWithMapping<DefinedAtom::codeARM_a>(v_t, v_a, name);
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_veneerAtoms[da] = v;
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return v;
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// Fake reference to show connection between parts of veneer.
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v_t->addReferenceELF_ARM(R_ARM_NONE, 0, v_a, 0);
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// Real reference to fixup.
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v_a->addReferenceELF_ARM(R_ARM_JUMP24, 0, da, 0);
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return v_t;
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}
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/// \brief Create a GOT entry for R_ARM_TLS_TPOFF32 reloc.
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@ -0,0 +1,94 @@
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# Check that mapping symbols are properly generated for veneers.
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# RUN: yaml2obj -format=elf -docnum 1 %s > %t-arm.o
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# RUN: yaml2obj -format=elf -docnum 2 %s > %t-thm.o
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# RUN: lld -flavor gnu -target arm-linux-gnu --defsym=main=fa \
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# RUN: -Bstatic --noinhibit-exec %t-arm.o %t-thm.o -o %t
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# RUN: llvm-readobj -symbols %t | FileCheck %s
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# CHECK: Name: $a.__ft_from_arm
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# CHECK: Name: $d.__ft_from_arm
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# CHECK: Name: $t.__fa_from_thumb
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# CHECK: Name: $a.__fa_from_thumb
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# arm.o
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---
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FileHeader:
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Class: ELFCLASS32
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Data: ELFDATA2LSB
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Type: ET_REL
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Machine: EM_ARM
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Flags: [ EF_ARM_EABI_VER5 ]
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Sections:
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- Name: .text
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Type: SHT_PROGBITS
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Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
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AddressAlign: 0x0000000000000004
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Content: 00482DE904B08DE2FEFFFFEA0030A0E10300A0E10088BDE8
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- Name: .rel.text
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Type: SHT_REL
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Link: .symtab
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AddressAlign: 0x0000000000000004
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Info: .text
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Relocations:
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- Offset: 0x0000000000000008
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Symbol: ft
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Type: R_ARM_JUMP24
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- Name: .data
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Type: SHT_PROGBITS
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Flags: [ SHF_WRITE, SHF_ALLOC ]
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AddressAlign: 0x0000000000000001
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Content: ''
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- Name: .bss
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Type: SHT_NOBITS
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Flags: [ SHF_WRITE, SHF_ALLOC ]
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AddressAlign: 0x0000000000000001
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Content: ''
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Symbols:
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Global:
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- Name: fa
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Type: STT_FUNC
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Section: .text
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- Name: ft
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# thm.o
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---
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FileHeader:
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Class: ELFCLASS32
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Data: ELFDATA2LSB
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Type: ET_REL
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Machine: EM_ARM
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Flags: [ EF_ARM_EABI_VER5 ]
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Sections:
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- Name: .text
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Type: SHT_PROGBITS
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Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
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AddressAlign: 0x0000000000000004
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Content: 80B500AFFFF7FEBF0346184680BD00BF
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- Name: .rel.text
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Type: SHT_REL
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Link: .symtab
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AddressAlign: 0x0000000000000004
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Info: .text
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Relocations:
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- Offset: 0x0000000000000004
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Symbol: fa
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Type: R_ARM_THM_JUMP24
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- Name: .data
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Type: SHT_PROGBITS
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Flags: [ SHF_WRITE, SHF_ALLOC ]
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AddressAlign: 0x0000000000000001
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Content: ''
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- Name: .bss
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Type: SHT_NOBITS
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Flags: [ SHF_WRITE, SHF_ALLOC ]
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AddressAlign: 0x0000000000000001
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Content: ''
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Symbols:
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Global:
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- Name: ft
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Type: STT_FUNC
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Section: .text
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Value: 0x0000000000000001
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- Name: fa
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...
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