//===-- 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/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.
uintptr_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.
intptr_t Addend;
/// 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),
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),
IsPCRel(IsPCRel), Size(Size) {}
};
class RelocationValueRef {
public:
unsigned SectionID;
intptr_t Addend;
const char *SymbolName;
RelocationValueRef(): SectionID(0), Addend(0), SymbolName(0) {}
inline bool operator==(const RelocationValueRef &Other) const {
return std::memcmp(this, &Other, sizeof(RelocationValueRef)) == 0;
}
inline bool operator <(const RelocationValueRef &Other) const {
return std::memcmp(this, &Other, sizeof(RelocationValueRef)) < 0;
}
};
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;
// 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;
inline unsigned getMaxStubSize() {
if (Arch == Triple::aarch64)
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 (Arch == Triple::mipsel || Arch == Triple::mips)
return 16;
else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le)
return 44;
else if (Arch == Triple::x86_64)
return 8; // GOT
else if (Arch == Triple::systemz)
return 16;
else
return 0;
}
inline unsigned getStubAlignment() {
if (Arch == Triple::systemz)
return 8;
else
return 1;
}
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 (sys::IsLittleEndianHost)
Value = sys::SwapByteOrder(Value);
*Addr = (Value >> 8) & 0xFF;
*(Addr+1) = Value & 0xFF;
}
void writeInt32BE(uint8_t *Addr, uint32_t Value) {
if (sys::IsLittleEndianHost)
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 (sys::IsLittleEndianHost)
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();
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.
if (GlobalSymbolTable.find(Name) == GlobalSymbolTable.end())
return 0;
SymbolLoc Loc = GlobalSymbolTable.lookup(Name);
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.
if (GlobalSymbolTable.find(Name) == GlobalSymbolTable.end())
return 0;
SymbolLoc Loc = GlobalSymbolTable.lookup(Name);
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 StringRef getEHFrameSection();
};
} // end namespace llvm
#endif