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//===-- RuntimeDyldELF.h - Run-time dynamic linker for MC-JIT ---*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// ELF support for MC-JIT runtime dynamic linker.
#include "RuntimeDyldImpl.h"
#include "llvm/ADT/DenseMap.h"
using namespace llvm;
namespace llvm {
namespace object {
class ELFObjectFileBase;
class RuntimeDyldELF : public RuntimeDyldImpl {
void resolveRelocation(const SectionEntry &Section, uint64_t Offset,
uint64_t Value, uint32_t Type, int64_t Addend,
uint64_t SymOffset = 0, SID SectionID = 0);
void resolveX86_64Relocation(const SectionEntry &Section, uint64_t Offset,
uint64_t Value, uint32_t Type, int64_t Addend,
uint64_t SymOffset);
void resolveX86Relocation(const SectionEntry &Section, uint64_t Offset,
uint32_t Value, uint32_t Type, int32_t Addend);
void resolveAArch64Relocation(const SectionEntry &Section, uint64_t Offset,
uint64_t Value, uint32_t Type, int64_t Addend);
bool resolveAArch64ShortBranch(unsigned SectionID, relocation_iterator RelI,
const RelocationValueRef &Value);
void resolveAArch64Branch(unsigned SectionID, const RelocationValueRef &Value,
relocation_iterator RelI, StubMap &Stubs);
void resolveARMRelocation(const SectionEntry &Section, uint64_t Offset,
uint32_t Value, uint32_t Type, int32_t Addend);
void resolvePPC32Relocation(const SectionEntry &Section, uint64_t Offset,
uint64_t Value, uint32_t Type, int64_t Addend);
void resolvePPC64Relocation(const SectionEntry &Section, uint64_t Offset,
uint64_t Value, uint32_t Type, int64_t Addend);
void resolveSystemZRelocation(const SectionEntry &Section, uint64_t Offset,
uint64_t Value, uint32_t Type, int64_t Addend);
void resolveBPFRelocation(const SectionEntry &Section, uint64_t Offset,
uint64_t Value, uint32_t Type, int64_t Addend);
unsigned getMaxStubSize() const override {
if (Arch == Triple::aarch64 || Arch == Triple::aarch64_be)
return 20; // movz; movk; movk; movk; br
if (Arch == Triple::arm || Arch == Triple::thumb)
return 8; // 32-bit instruction and 32-bit address
else if (IsMipsO32ABI || IsMipsN32ABI)
return 16;
else if (IsMipsN64ABI)
return 32;
else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le)
return 44;
else if (Arch == Triple::x86_64)
return 6; // 2-byte jmp instruction + 32-bit relative address
else if (Arch == Triple::systemz)
return 16;
return 0;
Align getStubAlignment() override {
if (Arch == Triple::systemz)
return Align(8);
return Align(1);
void setMipsABI(const ObjectFile &Obj) override;
Error findPPC64TOCSection(const object::ELFObjectFileBase &Obj,
ObjSectionToIDMap &LocalSections,
RelocationValueRef &Rel);
Error findOPDEntrySection(const object::ELFObjectFileBase &Obj,
ObjSectionToIDMap &LocalSections,
RelocationValueRef &Rel);
size_t getGOTEntrySize() override;
SectionEntry &getSection(unsigned SectionID) { return Sections[SectionID]; }
// Allocate no GOT entries for use in the given section.
uint64_t allocateGOTEntries(unsigned no);
// Find GOT entry corresponding to relocation or create new one.
uint64_t findOrAllocGOTEntry(const RelocationValueRef &Value,
unsigned GOTRelType);
// Resolve the relative address of GOTOffset in Section ID and place
// it at the given Offset
void resolveGOTOffsetRelocation(unsigned SectionID, uint64_t Offset,
uint64_t GOTOffset, uint32_t Type);
// For a GOT entry referenced from SectionID, compute a relocation entry
// that will place the final resolved value in the GOT slot
RelocationEntry computeGOTOffsetRE(uint64_t GOTOffset, uint64_t SymbolOffset,
unsigned Type);
// Compute the address in memory where we can find the placeholder
void *computePlaceholderAddress(unsigned SectionID, uint64_t Offset) const;
// Split out common case for creating the RelocationEntry for when the
// relocation requires no particular advanced processing.
void processSimpleRelocation(unsigned SectionID, uint64_t Offset, unsigned RelType, RelocationValueRef Value);
// Return matching *LO16 relocation (Mips specific)
uint32_t getMatchingLoRelocation(uint32_t RelType,
bool IsLocal = false) const;
// The tentative ID for the GOT section
unsigned GOTSectionID;
// Records the current number of allocated slots in the GOT
// (This would be equivalent to GOTEntries.size() were it not for relocations
// that consume more than one slot)
unsigned CurrentGOTIndex;
// A map from section to a GOT section that has entries for section's GOT
// relocations. (Mips64 specific)
DenseMap<SID, SID> SectionToGOTMap;
// A map to avoid duplicate got entries (Mips64 specific)
StringMap<uint64_t> GOTSymbolOffsets;
// *HI16 relocations will be added for resolving when we find matching
// *LO16 part. (Mips specific)
SmallVector<std::pair<RelocationValueRef, RelocationEntry>, 8> PendingRelocs;
// When a module is loaded we save the SectionID of the EH frame section
// in a table until we receive a request to register all unregistered
// EH frame sections with the memory manager.
SmallVector<SID, 2> UnregisteredEHFrameSections;
// Map between GOT relocation value and corresponding GOT offset
std::map<RelocationValueRef, uint64_t> GOTOffsetMap;
/// The ID of the current IFunc stub section
unsigned IFuncStubSectionID = 0;
/// The current offset into the IFunc stub section
uint64_t IFuncStubOffset = 0;
/// A IFunc stub and its original symbol
struct IFuncStub {
/// The offset of this stub in the IFunc stub section
uint64_t StubOffset;
/// The symbol table entry of the original symbol
SymbolTableEntry OriginalSymbol;
/// The IFunc stubs
SmallVector<IFuncStub, 2> IFuncStubs;
/// Create the code for the IFunc resolver at the given address. This code
/// works together with the stubs created in createIFuncStub() to call the
/// resolver function and then jump to the real function address.
/// It must not be larger than 64B.
void createIFuncResolver(uint8_t *Addr) const;
/// Create the code for an IFunc stub for the IFunc that is defined in
/// section IFuncSectionID at offset IFuncOffset. The IFunc resolver created
/// by createIFuncResolver() is defined in the section IFuncStubSectionID at
/// offset IFuncResolverOffset. The code should be written into the section
/// with the id IFuncStubSectionID at the offset IFuncStubOffset.
void createIFuncStub(unsigned IFuncStubSectionID,
uint64_t IFuncResolverOffset, uint64_t IFuncStubOffset,
unsigned IFuncSectionID, uint64_t IFuncOffset);
/// Return the maximum size of a stub created by createIFuncStub()
unsigned getMaxIFuncStubSize() const;
void processNewSymbol(const SymbolRef &ObjSymbol,
SymbolTableEntry &Entry) override;
bool relocationNeedsGot(const RelocationRef &R) const override;
bool relocationNeedsStub(const RelocationRef &R) const override;
// Process a GOTTPOFF TLS relocation for x86-64
// NOLINTNEXTLINE(readability-identifier-naming)
void processX86_64GOTTPOFFRelocation(unsigned SectionID, uint64_t Offset,
RelocationValueRef Value,
int64_t Addend);
// Process a TLSLD/TLSGD relocation for x86-64
// NOLINTNEXTLINE(readability-identifier-naming)
void processX86_64TLSRelocation(unsigned SectionID, uint64_t Offset,
uint64_t RelType, RelocationValueRef Value,
int64_t Addend,
const RelocationRef &GetAddrRelocation);
RuntimeDyldELF(RuntimeDyld::MemoryManager &MemMgr,
JITSymbolResolver &Resolver);
~RuntimeDyldELF() override;
static std::unique_ptr<RuntimeDyldELF>
create(Triple::ArchType Arch, RuntimeDyld::MemoryManager &MemMgr,
JITSymbolResolver &Resolver);
loadObject(const object::ObjectFile &O) override;
void resolveRelocation(const RelocationEntry &RE, uint64_t Value) override;
processRelocationRef(unsigned SectionID, relocation_iterator RelI,
const ObjectFile &Obj,
ObjSectionToIDMap &ObjSectionToID,
StubMap &Stubs) override;
bool isCompatibleFile(const object::ObjectFile &Obj) const override;
void registerEHFrames() override;
Error finalizeLoad(const ObjectFile &Obj,
ObjSectionToIDMap &SectionMap) override;
} // end namespace llvm