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llvm-mirror/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
Jim Grosbach 17ca2afa04 Tidy up a bit now that we're using the MemoryManager interface. 
llvm-svn: 129328
2011-04-12 00:23:32 +00:00

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//===-- RuntimeDyld.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.
//
//===----------------------------------------------------------------------===//
//
// Implementation of the MC-JIT runtime dynamic linker.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "dyld"
#include "llvm/ADT/OwningPtr.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/Twine.h"
#include "llvm/ExecutionEngine/RuntimeDyld.h"
#include "llvm/Object/MachOObject.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/Memory.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/system_error.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
using namespace llvm::object;
// Empty out-of-line virtual destructor as the key function.
RTDyldMemoryManager::~RTDyldMemoryManager() {}
namespace llvm {
class RuntimeDyldImpl {
unsigned CPUType;
unsigned CPUSubtype;
// The MemoryManager to load objects into.
RTDyldMemoryManager *MemMgr;
// For each function, we have a MemoryBlock of it's instruction data.
StringMap<sys::MemoryBlock> Functions;
// Master symbol table. As modules are loaded and external symbols are
// resolved, their addresses are stored here.
StringMap<uint64_t> SymbolTable;
// FIXME: Should have multiple data blocks, one for each loaded chunk of
// compiled code.
// sys::MemoryBlock Data;
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;
}
void extractFunction(StringRef Name, uint8_t *StartAddress,
uint8_t *EndAddress);
bool resolveRelocation(uint32_t BaseSection, macho::RelocationEntry RE,
SmallVectorImpl<void *> &SectionBases,
SmallVectorImpl<StringRef> &SymbolNames);
bool resolveX86_64Relocation(intptr_t Address, intptr_t Value, bool isPCRel,
unsigned Type, unsigned Size);
bool resolveARMRelocation(intptr_t Address, intptr_t Value, bool isPCRel,
unsigned Type, unsigned Size);
bool loadSegment32(const MachOObject *Obj,
const MachOObject::LoadCommandInfo *SegmentLCI,
const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC);
bool loadSegment64(const MachOObject *Obj,
const MachOObject::LoadCommandInfo *SegmentLCI,
const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC);
public:
RuntimeDyldImpl(RTDyldMemoryManager *mm) : MemMgr(mm), HasError(false) {}
bool loadObject(MemoryBuffer *InputBuffer);
void *getSymbolAddress(StringRef Name) {
// FIXME: Just look up as a function for now. Overly simple of course.
// Work in progress.
return Functions.lookup(Name).base();
}
// 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; }
};
void RuntimeDyldImpl::extractFunction(StringRef Name, uint8_t *StartAddress,
uint8_t *EndAddress) {
// Allocate memory for the function via the memory manager.
uintptr_t Size = EndAddress - StartAddress + 1;
uint8_t *Mem = MemMgr->startFunctionBody(Name.data(), Size);
assert(Size >= (uint64_t)(EndAddress - StartAddress + 1) &&
"Memory manager failed to allocate enough memory!");
// Copy the function payload into the memory block.
memcpy(Mem, StartAddress, EndAddress - StartAddress + 1);
MemMgr->endFunctionBody(Name.data(), Mem, Mem + Size);
// Remember where we put it.
Functions[Name] = sys::MemoryBlock(Mem, Size);
DEBUG(dbgs() << " allocated to " << Mem << "\n");
}
bool RuntimeDyldImpl::
resolveRelocation(uint32_t BaseSection, macho::RelocationEntry RE,
SmallVectorImpl<void *> &SectionBases,
SmallVectorImpl<StringRef> &SymbolNames) {
// struct relocation_info {
// int32_t r_address;
// uint32_t r_symbolnum:24,
// r_pcrel:1,
// r_length:2,
// r_extern:1,
// r_type:4;
// };
uint32_t SymbolNum = RE.Word1 & 0xffffff; // 24-bit value
bool isPCRel = (RE.Word1 >> 24) & 1;
unsigned Log2Size = (RE.Word1 >> 25) & 3;
bool isExtern = (RE.Word1 >> 27) & 1;
unsigned Type = (RE.Word1 >> 28) & 0xf;
if (RE.Word0 & macho::RF_Scattered)
return Error("NOT YET IMPLEMENTED: scattered relocations.");
// The address requiring a relocation.
intptr_t Address = (intptr_t)SectionBases[BaseSection] + RE.Word0;
// Figure out the target address of the relocation. If isExtern is true,
// this relocation references the symbol table, otherwise it references
// a section in the same object, numbered from 1 through NumSections
// (SectionBases is [0, NumSections-1]).
intptr_t Value;
if (isExtern) {
StringRef Name = SymbolNames[SymbolNum];
if (SymbolTable.lookup(Name)) {
// The symbol is in our symbol table, so we can resolve it directly.
Value = (intptr_t)SymbolTable[Name];
} else {
return Error("NOT YET IMPLEMENTED: relocations to pre-compiled code.");
}
DEBUG(dbgs() << "Resolve relocation(" << Type << ") from '" << Name
<< "' to " << format("0x%x", Address) << ".\n");
} else {
// For non-external relocations, the SymbolNum is actual a section number
// as described above.
Value = (intptr_t)SectionBases[SymbolNum - 1];
}
unsigned Size = 1 << Log2Size;
switch (CPUType) {
default: assert(0 && "Unsupported CPU type!");
case mach::CTM_x86_64:
return resolveX86_64Relocation(Address, Value, isPCRel, Type, Size);
case mach::CTM_ARM:
return resolveARMRelocation(Address, Value, isPCRel, Type, Size);
}
llvm_unreachable("");
}
bool RuntimeDyldImpl::resolveX86_64Relocation(intptr_t Address, intptr_t Value,
bool isPCRel, unsigned Type,
unsigned Size) {
// If the relocation is PC-relative, the value to be encoded is the
// pointer difference.
if (isPCRel)
// FIXME: It seems this value needs to be adjusted by 4 for an effective PC
// address. Is that expected? Only for branches, perhaps?
Value -= Address + 4;
switch(Type) {
default:
llvm_unreachable("Invalid relocation type!");
case macho::RIT_X86_64_Unsigned:
case macho::RIT_X86_64_Branch: {
// Mask in the target value a byte at a time (we don't have an alignment
// guarantee for the target address, so this is safest).
uint8_t *p = (uint8_t*)Address;
for (unsigned i = 0; i < Size; ++i) {
*p++ = (uint8_t)Value;
Value >>= 8;
}
return false;
}
case macho::RIT_X86_64_Signed:
case macho::RIT_X86_64_GOTLoad:
case macho::RIT_X86_64_GOT:
case macho::RIT_X86_64_Subtractor:
case macho::RIT_X86_64_Signed1:
case macho::RIT_X86_64_Signed2:
case macho::RIT_X86_64_Signed4:
case macho::RIT_X86_64_TLV:
return Error("Relocation type not implemented yet!");
}
return false;
}
bool RuntimeDyldImpl::resolveARMRelocation(intptr_t Address, intptr_t Value,
bool isPCRel, unsigned Type,
unsigned Size) {
// If the relocation is PC-relative, the value to be encoded is the
// pointer difference.
if (isPCRel) {
Value -= Address;
// ARM PCRel relocations have an effective-PC offset of two instructions
// (four bytes in Thumb mode, 8 bytes in ARM mode).
// FIXME: For now, assume ARM mode.
Value -= 8;
}
switch(Type) {
default:
case macho::RIT_Vanilla: {
llvm_unreachable("Invalid relocation type!");
// Mask in the target value a byte at a time (we don't have an alignment
// guarantee for the target address, so this is safest).
uint8_t *p = (uint8_t*)Address;
for (unsigned i = 0; i < Size; ++i) {
*p++ = (uint8_t)Value;
Value >>= 8;
}
break;
}
case macho::RIT_Pair:
case macho::RIT_Difference:
case macho::RIT_ARM_LocalDifference:
case macho::RIT_ARM_PreboundLazyPointer:
case macho::RIT_ARM_Branch24Bit: {
// Mask the value into the target address. We know instructions are
// 32-bit aligned, so we can do it all at once.
uint32_t *p = (uint32_t*)Address;
// The low two bits of the value are not encoded.
Value >>= 2;
// Mask the value to 24 bits.
Value &= 0xffffff;
// FIXME: If the destination is a Thumb function (and the instruction
// is a non-predicated BL instruction), we need to change it to a BLX
// instruction instead.
// Insert the value into the instruction.
*p = (*p & ~0xffffff) | Value;
break;
}
case macho::RIT_ARM_ThumbBranch22Bit:
case macho::RIT_ARM_ThumbBranch32Bit:
case macho::RIT_ARM_Half:
case macho::RIT_ARM_HalfDifference:
return Error("Relocation type not implemented yet!");
}
return false;
}
bool RuntimeDyldImpl::
loadSegment32(const MachOObject *Obj,
const MachOObject::LoadCommandInfo *SegmentLCI,
const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
InMemoryStruct<macho::SegmentLoadCommand> Segment32LC;
Obj->ReadSegmentLoadCommand(*SegmentLCI, Segment32LC);
if (!Segment32LC)
return Error("unable to load segment load command");
for (unsigned SectNum = 0; SectNum != Segment32LC->NumSections; ++SectNum) {
InMemoryStruct<macho::Section> Sect;
Obj->ReadSection(*SegmentLCI, SectNum, Sect);
if (!Sect)
return Error("unable to load section: '" + Twine(SectNum) + "'");
// FIXME: Improve check.
if (Sect->Flags != 0x80000400)
return Error("unsupported section type!");
// Address and names of symbols in the section.
typedef std::pair<uint64_t, StringRef> SymbolEntry;
SmallVector<SymbolEntry, 32> Symbols;
for (unsigned i = 0; i != SymtabLC->NumSymbolTableEntries; ++i) {
InMemoryStruct<macho::SymbolTableEntry> STE;
Obj->ReadSymbolTableEntry(SymtabLC->SymbolTableOffset, i, STE);
if (!STE)
return Error("unable to read symbol: '" + Twine(i) + "'");
if (STE->SectionIndex > Segment32LC->NumSections)
return Error("invalid section index for symbol: '" + Twine(i) + "'");
// Just skip symbols not defined in this section.
if ((unsigned)STE->SectionIndex - 1 != SectNum)
continue;
// Get the symbol name.
StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
// FIXME: Check the symbol type and flags.
if (STE->Type != 0xF) // external, defined in this section.
return Error("unexpected symbol type!");
if (STE->Flags != 0x0)
return Error("unexpected symbol type!");
uint64_t BaseAddress = Sect->Address;
uint64_t Address = BaseAddress + STE->Value;
// Remember the symbol.
Symbols.push_back(SymbolEntry(Address, Name));
DEBUG(dbgs() << "Function sym: '" << Name << "' @ " << Address << "\n");
}
// Sort the symbols by address, just in case they didn't come in that
// way.
array_pod_sort(Symbols.begin(), Symbols.end());
// Extract the function data.
uint8_t *Base = (uint8_t*)Obj->getData(Segment32LC->FileOffset,
Segment32LC->FileSize).data();
for (unsigned i = 0, e = Symbols.size() - 1; i != e; ++i) {
uint64_t StartOffset = Symbols[i].first;
uint64_t EndOffset = Symbols[i + 1].first - 1;
DEBUG(dbgs() << "Extracting function: " << Symbols[i].second
<< " from [" << StartOffset << ", " << EndOffset << "]\n");
extractFunction(Symbols[i].second, Base + StartOffset, Base + EndOffset);
}
// The last symbol we do after since the end address is calculated
// differently because there is no next symbol to reference.
uint64_t StartOffset = Symbols[Symbols.size() - 1].first;
uint64_t EndOffset = Sect->Size - 1;
DEBUG(dbgs() << "Extracting function: " << Symbols[Symbols.size()-1].second
<< " from [" << StartOffset << ", " << EndOffset << "]\n");
extractFunction(Symbols[Symbols.size()-1].second,
Base + StartOffset, Base + EndOffset);
}
return false;
}
bool RuntimeDyldImpl::
loadSegment64(const MachOObject *Obj,
const MachOObject::LoadCommandInfo *SegmentLCI,
const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
InMemoryStruct<macho::Segment64LoadCommand> Segment64LC;
Obj->ReadSegment64LoadCommand(*SegmentLCI, Segment64LC);
if (!Segment64LC)
return Error("unable to load segment load command");
for (unsigned SectNum = 0; SectNum != Segment64LC->NumSections; ++SectNum) {
InMemoryStruct<macho::Section64> Sect;
Obj->ReadSection64(*SegmentLCI, SectNum, Sect);
if (!Sect)
return Error("unable to load section: '" + Twine(SectNum) + "'");
// FIXME: Improve check.
if (Sect->Flags != 0x80000400)
return Error("unsupported section type!");
// Address and names of symbols in the section.
typedef std::pair<uint64_t, StringRef> SymbolEntry;
SmallVector<SymbolEntry, 64> Symbols;
for (unsigned i = 0; i != SymtabLC->NumSymbolTableEntries; ++i) {
InMemoryStruct<macho::Symbol64TableEntry> STE;
Obj->ReadSymbol64TableEntry(SymtabLC->SymbolTableOffset, i, STE);
if (!STE)
return Error("unable to read symbol: '" + Twine(i) + "'");
if (STE->SectionIndex > Segment64LC->NumSections)
return Error("invalid section index for symbol: '" + Twine(i) + "'");
// Just skip symbols not defined in this section.
if ((unsigned)STE->SectionIndex - 1 != SectNum)
continue;
// Get the symbol name.
StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
// FIXME: Check the symbol type and flags.
if (STE->Type != 0xF) // external, defined in this section.
return Error("unexpected symbol type!");
if (STE->Flags != 0x0)
return Error("unexpected symbol type!");
uint64_t BaseAddress = Sect->Address;
uint64_t Address = BaseAddress + STE->Value;
// Remember the symbol.
Symbols.push_back(SymbolEntry(Address, Name));
DEBUG(dbgs() << "Function sym: '" << Name << "' @ " << Address << "\n");
}
// Sort the symbols by address, just in case they didn't come in that
// way.
array_pod_sort(Symbols.begin(), Symbols.end());
// Extract the function data.
uint8_t *Base = (uint8_t*)Obj->getData(Segment64LC->FileOffset,
Segment64LC->FileSize).data();
for (unsigned i = 0, e = Symbols.size() - 1; i != e; ++i) {
uint64_t StartOffset = Symbols[i].first;
uint64_t EndOffset = Symbols[i + 1].first - 1;
DEBUG(dbgs() << "Extracting function: " << Symbols[i].second
<< " from [" << StartOffset << ", " << EndOffset << "]\n");
extractFunction(Symbols[i].second, Base + StartOffset, Base + EndOffset);
}
// The last symbol we do after since the end address is calculated
// differently because there is no next symbol to reference.
uint64_t StartOffset = Symbols[Symbols.size() - 1].first;
uint64_t EndOffset = Sect->Size - 1;
DEBUG(dbgs() << "Extracting function: " << Symbols[Symbols.size()-1].second
<< " from [" << StartOffset << ", " << EndOffset << "]\n");
extractFunction(Symbols[Symbols.size()-1].second,
Base + StartOffset, Base + EndOffset);
}
return false;
}
bool RuntimeDyldImpl::loadObject(MemoryBuffer *InputBuffer) {
// If the linker is in an error state, don't do anything.
if (hasError())
return true;
// Load the Mach-O wrapper object.
std::string ErrorStr;
OwningPtr<MachOObject> Obj(
MachOObject::LoadFromBuffer(InputBuffer, &ErrorStr));
if (!Obj)
return Error("unable to load object: '" + ErrorStr + "'");
// Get the CPU type information from the header.
const macho::Header &Header = Obj->getHeader();
// FIXME: Error checking that the loaded object is compatible with
// the system we're running on.
CPUType = Header.CPUType;
CPUSubtype = Header.CPUSubtype;
// Validate that the load commands match what we expect.
const MachOObject::LoadCommandInfo *SegmentLCI = 0, *SymtabLCI = 0,
*DysymtabLCI = 0;
for (unsigned i = 0; i != Header.NumLoadCommands; ++i) {
const MachOObject::LoadCommandInfo &LCI = Obj->getLoadCommandInfo(i);
switch (LCI.Command.Type) {
case macho::LCT_Segment:
case macho::LCT_Segment64:
if (SegmentLCI)
return Error("unexpected input object (multiple segments)");
SegmentLCI = &LCI;
break;
case macho::LCT_Symtab:
if (SymtabLCI)
return Error("unexpected input object (multiple symbol tables)");
SymtabLCI = &LCI;
break;
case macho::LCT_Dysymtab:
if (DysymtabLCI)
return Error("unexpected input object (multiple symbol tables)");
DysymtabLCI = &LCI;
break;
default:
return Error("unexpected input object (unexpected load command");
}
}
if (!SymtabLCI)
return Error("no symbol table found in object");
if (!SegmentLCI)
return Error("no symbol table found in object");
// Read and register the symbol table data.
InMemoryStruct<macho::SymtabLoadCommand> SymtabLC;
Obj->ReadSymtabLoadCommand(*SymtabLCI, SymtabLC);
if (!SymtabLC)
return Error("unable to load symbol table load command");
Obj->RegisterStringTable(*SymtabLC);
// Read the dynamic link-edit information, if present (not present in static
// objects).
if (DysymtabLCI) {
InMemoryStruct<macho::DysymtabLoadCommand> DysymtabLC;
Obj->ReadDysymtabLoadCommand(*DysymtabLCI, DysymtabLC);
if (!DysymtabLC)
return Error("unable to load dynamic link-exit load command");
// FIXME: We don't support anything interesting yet.
// if (DysymtabLC->LocalSymbolsIndex != 0)
// return Error("NOT YET IMPLEMENTED: local symbol entries");
// if (DysymtabLC->ExternalSymbolsIndex != 0)
// return Error("NOT YET IMPLEMENTED: non-external symbol entries");
// if (DysymtabLC->UndefinedSymbolsIndex != SymtabLC->NumSymbolTableEntries)
// return Error("NOT YET IMPLEMENTED: undefined symbol entries");
}
// Load the segment load command.
if (SegmentLCI->Command.Type == macho::LCT_Segment) {
if (loadSegment32(Obj.get(), SegmentLCI, SymtabLC))
return true;
} else {
if (loadSegment64(Obj.get(), SegmentLCI, SymtabLC))
return true;
}
return false;
}
//===----------------------------------------------------------------------===//
// RuntimeDyld class implementation
RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *MM) {
Dyld = new RuntimeDyldImpl(MM);
}
RuntimeDyld::~RuntimeDyld() {
delete Dyld;
}
bool RuntimeDyld::loadObject(MemoryBuffer *InputBuffer) {
return Dyld->loadObject(InputBuffer);
}
void *RuntimeDyld::getSymbolAddress(StringRef Name) {
return Dyld->getSymbolAddress(Name);
}
StringRef RuntimeDyld::getErrorString() {
return Dyld->getErrorString();
}
} // end namespace llvm
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