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+//===-- RuntimeDyldImpl.h - Run-time dynamic linker for MC-JIT --*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Interface for the implementations of runtime dynamic linker facilities.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_RUNTIME_DYLD_IMPL_H
+#define LLVM_RUNTIME_DYLD_IMPL_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/Triple.h"
+#include "llvm/ExecutionEngine/ObjectImage.h"
+#include "llvm/ExecutionEngine/RuntimeDyld.h"
+#include "llvm/Object/ObjectFile.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Support/Host.h"
+#include "llvm/Support/Mutex.h"
+#include "llvm/Support/SwapByteOrder.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/system_error.h"
+#include <map>
+
+using namespace llvm;
+using namespace llvm::object;
+
+namespace llvm {
+
+class ObjectBuffer;
+class Twine;
+
+
+/// SectionEntry - represents a section emitted into memory by the dynamic
+/// linker.
+class SectionEntry {
+public:
+ /// Name - section name.
+ StringRef Name;
+
+ /// Address - address in the linker's memory where the section resides.
+ uint8_t *Address;
+
+ /// Size - section size. Doesn't include the stubs.
+ size_t Size;
+
+ /// LoadAddress - the address of the section in the target process's memory.
+ /// Used for situations in which JIT-ed code is being executed in the address
+ /// space of a separate process. If the code executes in the same address
+ /// space where it was JIT-ed, this just equals Address.
+ uint64_t LoadAddress;
+
+ /// StubOffset - used for architectures with stub functions for far
+ /// relocations (like ARM).
+ uintptr_t StubOffset;
+
+ /// ObjAddress - address of the section in the in-memory object file. Used
+ /// for calculating relocations in some object formats (like MachO).
+ uintptr_t ObjAddress;
+
+ SectionEntry(StringRef name, uint8_t *address, size_t size,
+ uintptr_t objAddress)
+ : Name(name), Address(address), Size(size), LoadAddress((uintptr_t)address),
+ StubOffset(size), ObjAddress(objAddress) {}
+};
+
+/// RelocationEntry - used to represent relocations internally in the dynamic
+/// linker.
+class RelocationEntry {
+public:
+ /// SectionID - the section this relocation points to.
+ unsigned SectionID;
+
+ /// Offset - offset into the section.
+ uint64_t Offset;
+
+ /// RelType - relocation type.
+ uint32_t RelType;
+
+ /// Addend - the relocation addend encoded in the instruction itself. Also
+ /// used to make a relocation section relative instead of symbol relative.
+ int64_t Addend;
+
+ /// SymOffset - Section offset of the relocation entry's symbol (used for GOT
+ /// lookup).
+ uint64_t SymOffset;
+
+ /// True if this is a PCRel relocation (MachO specific).
+ bool IsPCRel;
+
+ /// The size of this relocation (MachO specific).
+ unsigned Size;
+
+ RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend)
+ : SectionID(id), Offset(offset), RelType(type), Addend(addend),
+ SymOffset(0), IsPCRel(false), Size(0) {}
+
+ RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
+ uint64_t symoffset)
+ : SectionID(id), Offset(offset), RelType(type), Addend(addend),
+ SymOffset(symoffset), IsPCRel(false), Size(0) {}
+
+ RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend,
+ bool IsPCRel, unsigned Size)
+ : SectionID(id), Offset(offset), RelType(type), Addend(addend),
+ SymOffset(0), IsPCRel(IsPCRel), Size(Size) {}
+};
+
+class RelocationValueRef {
+public:
+ unsigned SectionID;
+ uint64_t Offset;
+ int64_t Addend;
+ const char *SymbolName;
+ RelocationValueRef(): SectionID(0), Offset(0), Addend(0), SymbolName(0) {}
+
+ inline bool operator==(const RelocationValueRef &Other) const {
+ return SectionID == Other.SectionID && Offset == Other.Offset &&
+ Addend == Other.Addend && SymbolName == Other.SymbolName;
+ }
+ inline bool operator <(const RelocationValueRef &Other) const {
+ if (SectionID != Other.SectionID)
+ return SectionID < Other.SectionID;
+ if (Offset != Other.Offset)
+ return Offset < Other.Offset;
+ if (Addend != Other.Addend)
+ return Addend < Other.Addend;
+ return SymbolName < Other.SymbolName;
+ }
+};
+
+class RuntimeDyldImpl {
+protected:
+ // The MemoryManager to load objects into.
+ RTDyldMemoryManager *MemMgr;
+
+ // A list of all sections emitted by the dynamic linker. These sections are
+ // referenced in the code by means of their index in this list - SectionID.
+ typedef SmallVector<SectionEntry, 64> SectionList;
+ SectionList Sections;
+
+ typedef unsigned SID; // Type for SectionIDs
+ #define RTDYLD_INVALID_SECTION_ID ((SID)(-1))
+
+ // Keep a map of sections from object file to the SectionID which
+ // references it.
+ typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
+
+ // A global symbol table for symbols from all loaded modules. Maps the
+ // symbol name to a (SectionID, offset in section) pair.
+ typedef std::pair<unsigned, uintptr_t> SymbolLoc;
+ typedef StringMap<SymbolLoc> SymbolTableMap;
+ SymbolTableMap GlobalSymbolTable;
+
+ // Pair representing the size and alignment requirement for a common symbol.
+ typedef std::pair<unsigned, unsigned> CommonSymbolInfo;
+ // Keep a map of common symbols to their info pairs
+ typedef std::map<SymbolRef, CommonSymbolInfo> CommonSymbolMap;
+
+ // For each symbol, keep a list of relocations based on it. Anytime
+ // its address is reassigned (the JIT re-compiled the function, e.g.),
+ // the relocations get re-resolved.
+ // The symbol (or section) the relocation is sourced from is the Key
+ // in the relocation list where it's stored.
+ typedef SmallVector<RelocationEntry, 64> RelocationList;
+ // Relocations to sections already loaded. Indexed by SectionID which is the
+ // source of the address. The target where the address will be written is
+ // SectionID/Offset in the relocation itself.
+ DenseMap<unsigned, RelocationList> Relocations;
+
+ // Relocations to external symbols that are not yet resolved. Symbols are
+ // external when they aren't found in the global symbol table of all loaded
+ // modules. This map is indexed by symbol name.
+ StringMap<RelocationList> ExternalSymbolRelocations;
+
+ typedef std::map<RelocationValueRef, uintptr_t> StubMap;
+
+ Triple::ArchType Arch;
+ bool IsTargetLittleEndian;
+
+ // This mutex prevents simultaneously loading objects from two different
+ // threads. This keeps us from having to protect individual data structures
+ // and guarantees that section allocation requests to the memory manager
+ // won't be interleaved between modules. It is also used in mapSectionAddress
+ // and resolveRelocations to protect write access to internal data structures.
+ //
+ // loadObject may be called on the same thread during the handling of of
+ // processRelocations, and that's OK. The handling of the relocation lists
+ // is written in such a way as to work correctly if new elements are added to
+ // the end of the list while the list is being processed.
+ sys::Mutex lock;
+
+ virtual unsigned getMaxStubSize() = 0;
+ virtual unsigned getStubAlignment() = 0;
+
+ bool HasError;
+ std::string ErrorStr;
+
+ // Set the error state and record an error string.
+ bool Error(const Twine &Msg) {
+ ErrorStr = Msg.str();
+ HasError = true;
+ return true;
+ }
+
+ uint64_t getSectionLoadAddress(unsigned SectionID) {
+ return Sections[SectionID].LoadAddress;
+ }
+
+ uint8_t *getSectionAddress(unsigned SectionID) {
+ return (uint8_t*)Sections[SectionID].Address;
+ }
+
+ void writeInt16BE(uint8_t *Addr, uint16_t Value) {
+ if (IsTargetLittleEndian)
+ Value = sys::SwapByteOrder(Value);
+ *Addr = (Value >> 8) & 0xFF;
+ *(Addr+1) = Value & 0xFF;
+ }
+
+ void writeInt32BE(uint8_t *Addr, uint32_t Value) {
+ if (IsTargetLittleEndian)
+ Value = sys::SwapByteOrder(Value);
+ *Addr = (Value >> 24) & 0xFF;
+ *(Addr+1) = (Value >> 16) & 0xFF;
+ *(Addr+2) = (Value >> 8) & 0xFF;
+ *(Addr+3) = Value & 0xFF;
+ }
+
+ void writeInt64BE(uint8_t *Addr, uint64_t Value) {
+ if (IsTargetLittleEndian)
+ Value = sys::SwapByteOrder(Value);
+ *Addr = (Value >> 56) & 0xFF;
+ *(Addr+1) = (Value >> 48) & 0xFF;
+ *(Addr+2) = (Value >> 40) & 0xFF;
+ *(Addr+3) = (Value >> 32) & 0xFF;
+ *(Addr+4) = (Value >> 24) & 0xFF;
+ *(Addr+5) = (Value >> 16) & 0xFF;
+ *(Addr+6) = (Value >> 8) & 0xFF;
+ *(Addr+7) = Value & 0xFF;
+ }
+
+ /// \brief Given the common symbols discovered in the object file, emit a
+ /// new section for them and update the symbol mappings in the object and
+ /// symbol table.
+ void emitCommonSymbols(ObjectImage &Obj,
+ const CommonSymbolMap &CommonSymbols,
+ uint64_t TotalSize,
+ SymbolTableMap &SymbolTable);
+
+ /// \brief Emits section data from the object file to the MemoryManager.
+ /// \param IsCode if it's true then allocateCodeSection() will be
+ /// used for emits, else allocateDataSection() will be used.
+ /// \return SectionID.
+ unsigned emitSection(ObjectImage &Obj,
+ const SectionRef &Section,
+ bool IsCode);
+
+ /// \brief Find Section in LocalSections. If the secton is not found - emit
+ /// it and store in LocalSections.
+ /// \param IsCode if it's true then allocateCodeSection() will be
+ /// used for emmits, else allocateDataSection() will be used.
+ /// \return SectionID.
+ unsigned findOrEmitSection(ObjectImage &Obj,
+ const SectionRef &Section,
+ bool IsCode,
+ ObjSectionToIDMap &LocalSections);
+
+ // \brief Add a relocation entry that uses the given section.
+ void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID);
+
+ // \brief Add a relocation entry that uses the given symbol. This symbol may
+ // be found in the global symbol table, or it may be external.
+ void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName);
+
+ /// \brief Emits long jump instruction to Addr.
+ /// \return Pointer to the memory area for emitting target address.
+ uint8_t* createStubFunction(uint8_t *Addr);
+
+ /// \brief Resolves relocations from Relocs list with address from Value.
+ void resolveRelocationList(const RelocationList &Relocs, uint64_t Value);
+
+ /// \brief A object file specific relocation resolver
+ /// \param RE The relocation to be resolved
+ /// \param Value Target symbol address to apply the relocation action
+ virtual void resolveRelocation(const RelocationEntry &RE, uint64_t Value) = 0;
+
+ /// \brief Parses the object file relocation and stores it to Relocations
+ /// or SymbolRelocations (this depends on the object file type).
+ virtual void processRelocationRef(unsigned SectionID,
+ RelocationRef RelI,
+ ObjectImage &Obj,
+ ObjSectionToIDMap &ObjSectionToID,
+ const SymbolTableMap &Symbols,
+ StubMap &Stubs) = 0;
+
+ /// \brief Resolve relocations to external symbols.
+ void resolveExternalSymbols();
+
+ /// \brief Update GOT entries for external symbols.
+ // The base class does nothing. ELF overrides this.
+ virtual void updateGOTEntries(StringRef Name, uint64_t Addr) {}
+
+ virtual ObjectImage *createObjectImage(ObjectBuffer *InputBuffer);
+public:
+ RuntimeDyldImpl(RTDyldMemoryManager *mm) : MemMgr(mm), HasError(false) {}
+
+ virtual ~RuntimeDyldImpl();
+
+ ObjectImage *loadObject(ObjectBuffer *InputBuffer);
+
+ void *getSymbolAddress(StringRef Name) {
+ // FIXME: Just look up as a function for now. Overly simple of course.
+ // Work in progress.
+ SymbolTableMap::const_iterator pos = GlobalSymbolTable.find(Name);
+ if (pos == GlobalSymbolTable.end())
+ return 0;
+ SymbolLoc Loc = pos->second;
+ return getSectionAddress(Loc.first) + Loc.second;
+ }
+
+ uint64_t getSymbolLoadAddress(StringRef Name) {
+ // FIXME: Just look up as a function for now. Overly simple of course.
+ // Work in progress.
+ SymbolTableMap::const_iterator pos = GlobalSymbolTable.find(Name);
+ if (pos == GlobalSymbolTable.end())
+ return 0;
+ SymbolLoc Loc = pos->second;
+ return getSectionLoadAddress(Loc.first) + Loc.second;
+ }
+
+ void resolveRelocations();
+
+ void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
+
+ void mapSectionAddress(const void *LocalAddress, uint64_t TargetAddress);
+
+ // Is the linker in an error state?
+ bool hasError() { return HasError; }
+
+ // Mark the error condition as handled and continue.
+ void clearError() { HasError = false; }
+
+ // Get the error message.
+ StringRef getErrorString() { return ErrorStr; }
+
+ virtual bool isCompatibleFormat(const ObjectBuffer *Buffer) const = 0;
+
+ virtual void registerEHFrames();
+
+ virtual void deregisterEHFrames();
+
+ virtual void finalizeLoad(ObjSectionToIDMap &SectionMap) {}
+};
+
+} // end namespace llvm
+
+
+#endif
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