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llvm-6502/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldMachO.cpp
Ahmed Charles b0934ab7d8 Remove dead code. Improve llvm_unreachable text. Simplify some control flow. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150918 91177308-0d34-0410-b5e6-96231b3b80d8
2012-02-19 11:37:01 +00:00

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//===-- RuntimeDyldMachO.cpp - 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/StringRef.h"
#include "llvm/ADT/STLExtras.h"
#include "RuntimeDyldMachO.h"
using namespace llvm;
using namespace llvm::object;
namespace llvm {
bool RuntimeDyldMachO::
resolveRelocation(uint8_t *Address, uint64_t Value, bool isPCRel,
unsigned Type, unsigned Size, int64_t Addend) {
// This just dispatches to the proper target specific routine.
switch (CPUType) {
default: llvm_unreachable("Unsupported CPU type!");
case mach::CTM_x86_64:
return resolveX86_64Relocation((uintptr_t)Address, (uintptr_t)Value,
isPCRel, Type, Size, Addend);
case mach::CTM_ARM:
return resolveARMRelocation((uintptr_t)Address, (uintptr_t)Value,
isPCRel, Type, Size, Addend);
}
}
bool RuntimeDyldMachO::
resolveX86_64Relocation(uintptr_t Address, uintptr_t Value, bool isPCRel,
unsigned Type, unsigned Size, int64_t Addend) {
// 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_Signed1:
case macho::RIT_X86_64_Signed2:
case macho::RIT_X86_64_Signed4:
case macho::RIT_X86_64_Signed:
case macho::RIT_X86_64_Unsigned:
case macho::RIT_X86_64_Branch: {
Value += Addend;
// 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_GOTLoad:
case macho::RIT_X86_64_GOT:
case macho::RIT_X86_64_Subtractor:
case macho::RIT_X86_64_TLV:
return Error("Relocation type not implemented yet!");
}
}
bool RuntimeDyldMachO::
resolveARMRelocation(uintptr_t Address, uintptr_t Value, bool isPCRel,
unsigned Type, unsigned Size, int64_t Addend) {
// 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:
llvm_unreachable("Invalid relocation type!");
case macho::RIT_Vanilla: {
// 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_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:
case macho::RIT_Pair:
case macho::RIT_Difference:
case macho::RIT_ARM_LocalDifference:
case macho::RIT_ARM_PreboundLazyPointer:
return Error("Relocation type not implemented yet!");
}
return false;
}
bool RuntimeDyldMachO::
loadSegment32(const MachOObject *Obj,
const MachOObject::LoadCommandInfo *SegmentLCI,
const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
// FIXME: This should really be combined w/ loadSegment64. Templatized
// function on the 32/64 datatypes maybe?
InMemoryStruct<macho::SegmentLoadCommand> SegmentLC;
Obj->ReadSegmentLoadCommand(*SegmentLCI, SegmentLC);
if (!SegmentLC)
return Error("unable to load segment load command");
SmallVector<unsigned, 16> SectionMap;
for (unsigned SectNum = 0; SectNum != SegmentLC->NumSections; ++SectNum) {
InMemoryStruct<macho::Section> Sect;
Obj->ReadSection(*SegmentLCI, SectNum, Sect);
if (!Sect)
return Error("unable to load section: '" + Twine(SectNum) + "'");
// Allocate memory via the MM for the section.
uint8_t *Buffer;
uint32_t SectionID = Sections.size();
if (Sect->Flags != 0x80000400)
Buffer = MemMgr->allocateCodeSection(Sect->Size, Sect->Align, SectionID);
else
Buffer = MemMgr->allocateDataSection(Sect->Size, Sect->Align, SectionID);
DEBUG(dbgs() << "Loading "
<< ((Sect->Flags == 0x80000400) ? "text" : "data")
<< " (ID #" << SectionID << ")"
<< " '" << Sect->SegmentName << ","
<< Sect->Name << "' of size " << Sect->Size
<< " to address " << Buffer << ".\n");
// Copy the payload from the object file into the allocated buffer.
uint8_t *Base = (uint8_t*)Obj->getData(SegmentLC->FileOffset,
SegmentLC->FileSize).data();
memcpy(Buffer, Base + Sect->Address, Sect->Size);
// Remember what got allocated for this SectionID.
Sections.push_back(sys::MemoryBlock(Buffer, Sect->Size));
SectionLocalMemToID[Buffer] = SectionID;
// By default, the load address of a section is its memory buffer.
SectionLoadAddress.push_back((uint64_t)Buffer);
// Keep a map of object file section numbers to corresponding SectionIDs
// while processing the file.
SectionMap.push_back(SectionID);
}
// Process the symbol table.
SmallVector<StringRef, 64> SymbolNames;
processSymbols32(Obj, SectionMap, SymbolNames, SymtabLC);
// Process the relocations for each section we're loading.
Relocations.grow(Relocations.size() + SegmentLC->NumSections);
for (unsigned SectNum = 0; SectNum != SegmentLC->NumSections; ++SectNum) {
InMemoryStruct<macho::Section> Sect;
Obj->ReadSection(*SegmentLCI, SectNum, Sect);
if (!Sect)
return Error("unable to load section: '" + Twine(SectNum) + "'");
for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) {
InMemoryStruct<macho::RelocationEntry> RE;
Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE);
if (RE->Word0 & macho::RF_Scattered)
return Error("NOT YET IMPLEMENTED: scattered relocations.");
// Word0 of the relocation is the offset into the section where the
// relocation should be applied. We need to translate that into an
// offset into a function since that's our atom.
uint32_t Offset = RE->Word0;
bool isExtern = (RE->Word1 >> 27) & 1;
// FIXME: Get the relocation addend from the target address.
// FIXME: VERY imporant for internal relocations.
// Figure out the source symbol 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]).
uint32_t SourceNum = RE->Word1 & 0xffffff; // 24-bit value
if (!isExtern) {
assert(SourceNum > 0 && "Invalid relocation section number!");
unsigned SectionID = SectionMap[SourceNum - 1];
unsigned TargetID = SectionMap[SectNum];
DEBUG(dbgs() << "Internal relocation at Section #"
<< TargetID << " + " << Offset
<< " from Section #"
<< SectionID << " (Word1: "
<< format("0x%x", RE->Word1) << ")\n");
// Store the relocation information. It will get resolved when
// the section addresses are assigned.
Relocations[SectionID].push_back(RelocationEntry(TargetID,
Offset,
RE->Word1,
0 /*Addend*/));
} else {
StringRef SourceName = SymbolNames[SourceNum];
// Now store the relocation information. Associate it with the source
// symbol. Just add it to the unresolved list and let the general
// path post-load resolve it if we know where the symbol is.
UnresolvedRelocations[SourceName].push_back(RelocationEntry(SectNum,
Offset,
RE->Word1,
0 /*Addend*/));
DEBUG(dbgs() << "Relocation at Section #" << SectNum << " + " << Offset
<< " from '" << SourceName << "(Word1: "
<< format("0x%x", RE->Word1) << ")\n");
}
}
}
// Resolve the addresses of any symbols that were defined in this segment.
for (int i = 0, e = SymbolNames.size(); i != e; ++i)
resolveSymbol(SymbolNames[i]);
return false;
}
bool RuntimeDyldMachO::
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");
SmallVector<unsigned, 16> SectionMap;
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) + "'");
// Allocate memory via the MM for the section.
uint8_t *Buffer;
uint32_t SectionID = Sections.size();
unsigned Align = 1 << Sect->Align; // .o file has log2 alignment.
if (Sect->Flags == 0x80000400)
Buffer = MemMgr->allocateCodeSection(Sect->Size, Align, SectionID);
else
Buffer = MemMgr->allocateDataSection(Sect->Size, Align, SectionID);
DEBUG(dbgs() << "Loading "
<< ((Sect->Flags == 0x80000400) ? "text" : "data")
<< " (ID #" << SectionID << ")"
<< " '" << Sect->SegmentName << ","
<< Sect->Name << "' of size " << Sect->Size
<< " (align " << Align << ")"
<< " to address " << Buffer << ".\n");
// Copy the payload from the object file into the allocated buffer.
uint8_t *Base = (uint8_t*)Obj->getData(Segment64LC->FileOffset,
Segment64LC->FileSize).data();
memcpy(Buffer, Base + Sect->Address, Sect->Size);
// Remember what got allocated for this SectionID.
Sections.push_back(sys::MemoryBlock(Buffer, Sect->Size));
SectionLocalMemToID[Buffer] = SectionID;
// By default, the load address of a section is its memory buffer.
SectionLoadAddress.push_back((uint64_t)Buffer);
// Keep a map of object file section numbers to corresponding SectionIDs
// while processing the file.
SectionMap.push_back(SectionID);
}
// Process the symbol table.
SmallVector<StringRef, 64> SymbolNames;
processSymbols64(Obj, SectionMap, SymbolNames, SymtabLC);
// Process the relocations for each section we're loading.
Relocations.grow(Relocations.size() + Segment64LC->NumSections);
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) + "'");
for (unsigned j = 0; j != Sect->NumRelocationTableEntries; ++j) {
InMemoryStruct<macho::RelocationEntry> RE;
Obj->ReadRelocationEntry(Sect->RelocationTableOffset, j, RE);
if (RE->Word0 & macho::RF_Scattered)
return Error("NOT YET IMPLEMENTED: scattered relocations.");
// Word0 of the relocation is the offset into the section where the
// relocation should be applied. We need to translate that into an
// offset into a function since that's our atom.
uint32_t Offset = RE->Word0;
bool isExtern = (RE->Word1 >> 27) & 1;
// FIXME: Get the relocation addend from the target address.
// FIXME: VERY imporant for internal relocations.
// Figure out the source symbol 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]).
uint32_t SourceNum = RE->Word1 & 0xffffff; // 24-bit value
if (!isExtern) {
assert(SourceNum > 0 && "Invalid relocation section number!");
unsigned SectionID = SectionMap[SourceNum - 1];
unsigned TargetID = SectionMap[SectNum];
DEBUG(dbgs() << "Internal relocation at Section #"
<< TargetID << " + " << Offset
<< " from Section #"
<< SectionID << " (Word1: "
<< format("0x%x", RE->Word1) << ")\n");
// Store the relocation information. It will get resolved when
// the section addresses are assigned.
Relocations[SectionID].push_back(RelocationEntry(TargetID,
Offset,
RE->Word1,
0 /*Addend*/));
} else {
StringRef SourceName = SymbolNames[SourceNum];
// Now store the relocation information. Associate it with the source
// symbol. Just add it to the unresolved list and let the general
// path post-load resolve it if we know where the symbol is.
UnresolvedRelocations[SourceName].push_back(RelocationEntry(SectNum,
Offset,
RE->Word1,
0 /*Addend*/));
DEBUG(dbgs() << "Relocation at Section #" << SectNum << " + " << Offset
<< " from '" << SourceName << "(Word1: "
<< format("0x%x", RE->Word1) << ")\n");
}
}
}
// Resolve the addresses of any symbols that were defined in this segment.
for (int i = 0, e = SymbolNames.size(); i != e; ++i)
resolveSymbol(SymbolNames[i]);
return false;
}
bool RuntimeDyldMachO::
processSymbols32(const MachOObject *Obj,
SmallVectorImpl<unsigned> &SectionMap,
SmallVectorImpl<StringRef> &SymbolNames,
const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
// FIXME: Combine w/ processSymbols64. Factor 64/32 datatype and such.
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) + "'");
// Get the symbol name.
StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
SymbolNames.push_back(Name);
// FIXME: Check the symbol type and flags.
if (STE->Type != 0xF) // external, defined in this segment.
continue;
// Flags in the upper nibble we don't care about.
if ((STE->Flags & 0xf) != 0x0)
continue;
// Remember the symbol.
uint32_t SectionID = SectionMap[STE->SectionIndex - 1];
SymbolTable[Name] = SymbolLoc(SectionID, STE->Value);
DEBUG(dbgs() << "Symbol: '" << Name << "' @ "
<< (getSectionAddress(SectionID) + STE->Value)
<< "\n");
}
return false;
}
bool RuntimeDyldMachO::
processSymbols64(const MachOObject *Obj,
SmallVectorImpl<unsigned> &SectionMap,
SmallVectorImpl<StringRef> &SymbolNames,
const InMemoryStruct<macho::SymtabLoadCommand> &SymtabLC) {
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) + "'");
// Get the symbol name.
StringRef Name = Obj->getStringAtIndex(STE->StringIndex);
SymbolNames.push_back(Name);
// FIXME: Check the symbol type and flags.
if (STE->Type != 0xF) // external, defined in this segment.
continue;
// Flags in the upper nibble we don't care about.
if ((STE->Flags & 0xf) != 0x0)
continue;
// Remember the symbol.
uint32_t SectionID = SectionMap[STE->SectionIndex - 1];
SymbolTable[Name] = SymbolLoc(SectionID, STE->Value);
DEBUG(dbgs() << "Symbol: '" << Name << "' @ "
<< (getSectionAddress(SectionID) + STE->Value)
<< "\n");
}
return false;
}
// resolveSymbol - Resolve any relocations to the specified symbol if
// we know where it lives.
void RuntimeDyldMachO::resolveSymbol(StringRef Name) {
StringMap<SymbolLoc>::const_iterator Loc = SymbolTable.find(Name);
if (Loc == SymbolTable.end())
return;
RelocationList &Relocs = UnresolvedRelocations[Name];
DEBUG(dbgs() << "Resolving symbol '" << Name << "'\n");
for (int i = 0, e = Relocs.size(); i != e; ++i) {
// Change the relocation to be section relative rather than symbol
// relative and move it to the resolved relocation list.
RelocationEntry Entry = Relocs[i];
Entry.Addend += Loc->second.second;
Relocations[Loc->second.first].push_back(Entry);
}
// FIXME: Keep a worklist of the relocations we've added so that we can
// resolve more selectively later.
Relocs.clear();
}
bool RuntimeDyldMachO::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 segments 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;
}
// Assign the addresses of the sections from the object so that any
// relocations to them get set properly.
// FIXME: This is done directly from the client at the moment. We should
// default the values to the local storage, at least when the target arch
// is the same as the host arch.
return false;
}
// Assign an address to a symbol name and resolve all the relocations
// associated with it.
void RuntimeDyldMachO::reassignSectionAddress(unsigned SectionID,
uint64_t Addr) {
// The address to use for relocation resolution is not
// the address of the local section buffer. We must be doing
// a remote execution environment of some sort. Re-apply any
// relocations referencing this section with the given address.
//
// Addr is a uint64_t because we can't assume the pointer width
// of the target is the same as that of the host. Just use a generic
// "big enough" type.
SectionLoadAddress[SectionID] = Addr;
RelocationList &Relocs = Relocations[SectionID];
for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
RelocationEntry &RE = Relocs[i];
uint8_t *Target = (uint8_t*)Sections[RE.SectionID].base() + RE.Offset;
bool isPCRel = (RE.Data >> 24) & 1;
unsigned Type = (RE.Data >> 28) & 0xf;
unsigned Size = 1 << ((RE.Data >> 25) & 3);
DEBUG(dbgs() << "Resolving relocation at Section #" << RE.SectionID
<< " + " << RE.Offset << " (" << format("%p", Target) << ")"
<< " from Section #" << SectionID << " (" << format("%p", Addr) << ")"
<< "(" << (isPCRel ? "pcrel" : "absolute")
<< ", type: " << Type << ", Size: " << Size << ", Addend: "
<< RE.Addend << ").\n");
resolveRelocation(Target, Addr, isPCRel, Type, Size, RE.Addend);
}
}
bool RuntimeDyldMachO::isKnownFormat(const MemoryBuffer *InputBuffer) {
StringRef Magic = InputBuffer->getBuffer().slice(0, 4);
if (Magic == "\xFE\xED\xFA\xCE") return true;
if (Magic == "\xCE\xFA\xED\xFE") return true;
if (Magic == "\xFE\xED\xFA\xCF") return true;
if (Magic == "\xCF\xFA\xED\xFE") return true;
return false;
}
} // end namespace llvm
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