//===-- RuntimeDyld.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/ExecutionEngine/RuntimeDyld.h"
#include "ObjectImageCommon.h"
#include "RuntimeDyldELF.h"
#include "RuntimeDyldImpl.h"
#include "RuntimeDyldMachO.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Object/ELF.h"
using namespace llvm;
using namespace llvm::object;
// Empty out-of-line virtual destructor as the key function.
RuntimeDyldImpl::~RuntimeDyldImpl() {}
namespace llvm {
StringRef RuntimeDyldImpl::getEHFrameSection() {
return StringRef();
}
// Resolve the relocations for all symbols we currently know about.
void RuntimeDyldImpl::resolveRelocations() {
// First, resolve relocations associated with external symbols.
resolveExternalSymbols();
// Just iterate over the sections we have and resolve all the relocations
// in them. Gross overkill, but it gets the job done.
for (int i = 0, e = Sections.size(); i != e; ++i) {
uint64_t Addr = Sections[i].LoadAddress;
DEBUG(dbgs() << "Resolving relocations Section #" << i
<< "\t" << format("%p", (uint8_t *)Addr)
<< "\n");
resolveRelocationList(Relocations[i], Addr);
}
}
void RuntimeDyldImpl::mapSectionAddress(const void *LocalAddress,
uint64_t TargetAddress) {
for (unsigned i = 0, e = Sections.size(); i != e; ++i) {
if (Sections[i].Address == LocalAddress) {
reassignSectionAddress(i, TargetAddress);
return;
}
}
llvm_unreachable("Attempting to remap address of unknown section!");
}
// Subclasses can implement this method to create specialized image instances.
// The caller owns the pointer that is returned.
ObjectImage *RuntimeDyldImpl::createObjectImage(ObjectBuffer *InputBuffer) {
return new ObjectImageCommon(InputBuffer);
}
ObjectImage *RuntimeDyldImpl::loadObject(ObjectBuffer *InputBuffer) {
OwningPtr<ObjectImage> obj(createObjectImage(InputBuffer));
if (!obj)
report_fatal_error("Unable to create object image from memory buffer!");
Arch = (Triple::ArchType)obj->getArch();
// Symbols found in this object
StringMap<SymbolLoc> LocalSymbols;
// Used sections from the object file
ObjSectionToIDMap LocalSections;
// Common symbols requiring allocation, with their sizes and alignments
CommonSymbolMap CommonSymbols;
// Maximum required total memory to allocate all common symbols
uint64_t CommonSize = 0;
error_code err;
// Parse symbols
DEBUG(dbgs() << "Parse symbols:\n");
for (symbol_iterator i = obj->begin_symbols(), e = obj->end_symbols();
i != e; i.increment(err)) {
Check(err);
object::SymbolRef::Type SymType;
StringRef Name;
Check(i->getType(SymType));
Check(i->getName(Name));
uint32_t flags;
Check(i->getFlags(flags));
bool isCommon = flags & SymbolRef::SF_Common;
if (isCommon) {
// Add the common symbols to a list. We'll allocate them all below.
uint32_t Align;
Check(i->getAlignment(Align));
uint64_t Size = 0;
Check(i->getSize(Size));
CommonSize += Size + Align;
CommonSymbols[*i] = CommonSymbolInfo(Size, Align);
} else {
if (SymType == object::SymbolRef::ST_Function ||
SymType == object::SymbolRef::ST_Data ||
SymType == object::SymbolRef::ST_Unknown) {
uint64_t FileOffset;
StringRef SectionData;
bool IsCode;
section_iterator si = obj->end_sections();
Check(i->getFileOffset(FileOffset));
Check(i->getSection(si));
if (si == obj->end_sections()) continue;
Check(si->getContents(SectionData));
Check(si->isText(IsCode));
const uint8_t* SymPtr = (const uint8_t*)InputBuffer->getBufferStart() +
(uintptr_t)FileOffset;
uintptr_t SectOffset = (uintptr_t)(SymPtr -
(const uint8_t*)SectionData.begin());
unsigned SectionID = findOrEmitSection(*obj, *si, IsCode, LocalSections);
LocalSymbols[Name.data()] = SymbolLoc(SectionID, SectOffset);
DEBUG(dbgs() << "\tFileOffset: " << format("%p", (uintptr_t)FileOffset)
<< " flags: " << flags
<< " SID: " << SectionID
<< " Offset: " << format("%p", SectOffset));
GlobalSymbolTable[Name] = SymbolLoc(SectionID, SectOffset);
}
}
DEBUG(dbgs() << "\tType: " << SymType << " Name: " << Name << "\n");
}
// Allocate common symbols
if (CommonSize != 0)
emitCommonSymbols(*obj, CommonSymbols, CommonSize, LocalSymbols);
// Parse and process relocations
DEBUG(dbgs() << "Parse relocations:\n");
for (section_iterator si = obj->begin_sections(),
se = obj->end_sections(); si != se; si.increment(err)) {
Check(err);
bool isFirstRelocation = true;
unsigned SectionID = 0;
StubMap Stubs;
section_iterator RelocatedSection = si->getRelocatedSection();
for (relocation_iterator i = si->begin_relocations(),
e = si->end_relocations(); i != e; i.increment(err)) {
Check(err);
// If it's the first relocation in this section, find its SectionID
if (isFirstRelocation) {
SectionID =
findOrEmitSection(*obj, *RelocatedSection, true, LocalSections);
DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
isFirstRelocation = false;
}
processRelocationRef(SectionID, *i, *obj, LocalSections, LocalSymbols,
Stubs);
}
}
return obj.take();
}
void RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
const CommonSymbolMap &CommonSymbols,
uint64_t TotalSize,
SymbolTableMap &SymbolTable) {
// Allocate memory for the section
unsigned SectionID = Sections.size();
uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void*),
SectionID, false);
if (!Addr)
report_fatal_error("Unable to allocate memory for common symbols!");
uint64_t Offset = 0;
Sections.push_back(SectionEntry(StringRef(), Addr, TotalSize, 0));
memset(Addr, 0, TotalSize);
DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
<< " new addr: " << format("%p", Addr)
<< " DataSize: " << TotalSize
<< "\n");
// Assign the address of each symbol
for (CommonSymbolMap::const_iterator it = CommonSymbols.begin(),
itEnd = CommonSymbols.end(); it != itEnd; it++) {
uint64_t Size = it->second.first;
uint64_t Align = it->second.second;
StringRef Name;
it->first.getName(Name);
if (Align) {
// This symbol has an alignment requirement.
uint64_t AlignOffset = OffsetToAlignment((uint64_t)Addr, Align);
Addr += AlignOffset;
Offset += AlignOffset;
DEBUG(dbgs() << "Allocating common symbol " << Name << " address " <<
format("%p\n", Addr));
}
Obj.updateSymbolAddress(it->first, (uint64_t)Addr);
SymbolTable[Name.data()] = SymbolLoc(SectionID, Offset);
Offset += Size;
Addr += Size;
}
}
unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
const SectionRef &Section,
bool IsCode) {
unsigned StubBufSize = 0,
StubSize = getMaxStubSize();
error_code err;
const ObjectFile *ObjFile = Obj.getObjectFile();
// FIXME: this is an inefficient way to handle this. We should computed the
// necessary section allocation size in loadObject by walking all the sections
// once.
if (StubSize > 0) {
for (section_iterator SI = ObjFile->begin_sections(),
SE = ObjFile->end_sections();
SI != SE; SI.increment(err), Check(err)) {
section_iterator RelSecI = SI->getRelocatedSection();
if (!(RelSecI == Section))
continue;
for (relocation_iterator I = SI->begin_relocations(),
E = SI->end_relocations(); I != E; I.increment(err), Check(err)) {
StubBufSize += StubSize;
}
}
}
StringRef data;
uint64_t Alignment64;
Check(Section.getContents(data));
Check(Section.getAlignment(Alignment64));
unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
bool IsRequired;
bool IsVirtual;
bool IsZeroInit;
bool IsReadOnly;
uint64_t DataSize;
StringRef Name;
Check(Section.isRequiredForExecution(IsRequired));
Check(Section.isVirtual(IsVirtual));
Check(Section.isZeroInit(IsZeroInit));
Check(Section.isReadOnlyData(IsReadOnly));
Check(Section.getSize(DataSize));
Check(Section.getName(Name));
if (StubSize > 0) {
unsigned StubAlignment = getStubAlignment();
unsigned EndAlignment = (DataSize | Alignment) & -(DataSize | Alignment);
if (StubAlignment > EndAlignment)
StubBufSize += StubAlignment - EndAlignment;
}
unsigned Allocate;
unsigned SectionID = Sections.size();
uint8_t *Addr;
const char *pData = 0;
// Some sections, such as debug info, don't need to be loaded for execution.
// Leave those where they are.
if (IsRequired) {
Allocate = DataSize + StubBufSize;
Addr = IsCode
? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
: MemMgr->allocateDataSection(Allocate, Alignment, SectionID, IsReadOnly);
if (!Addr)
report_fatal_error("Unable to allocate section memory!");
// Virtual sections have no data in the object image, so leave pData = 0
if (!IsVirtual)
pData = data.data();
// Zero-initialize or copy the data from the image
if (IsZeroInit || IsVirtual)
memset(Addr, 0, DataSize);
else
memcpy(Addr, pData, DataSize);
DEBUG(dbgs() << "emitSection SectionID: " << SectionID
<< " Name: " << Name
<< " obj addr: " << format("%p", pData)
<< " new addr: " << format("%p", Addr)
<< " DataSize: " << DataSize
<< " StubBufSize: " << StubBufSize
<< " Allocate: " << Allocate
<< "\n");
Obj.updateSectionAddress(Section, (uint64_t)Addr);
}
else {
// Even if we didn't load the section, we need to record an entry for it
// to handle later processing (and by 'handle' I mean don't do anything
// with these sections).
Allocate = 0;
Addr = 0;
DEBUG(dbgs() << "emitSection SectionID: " << SectionID
<< " Name: " << Name
<< " obj addr: " << format("%p", data.data())
<< " new addr: 0"
<< " DataSize: " << DataSize
<< " StubBufSize: " << StubBufSize
<< " Allocate: " << Allocate
<< "\n");
}
Sections.push_back(SectionEntry(Name, Addr, DataSize, (uintptr_t)pData));
return SectionID;
}
unsigned RuntimeDyldImpl::findOrEmitSection(ObjectImage &Obj,
const SectionRef &Section,
bool IsCode,
ObjSectionToIDMap &LocalSections) {
unsigned SectionID = 0;
ObjSectionToIDMap::iterator i = LocalSections.find(Section);
if (i != LocalSections.end())
SectionID = i->second;
else {
SectionID = emitSection(Obj, Section, IsCode);
LocalSections[Section] = SectionID;
}
return SectionID;
}
void RuntimeDyldImpl::addRelocationForSection(const RelocationEntry &RE,
unsigned SectionID) {
Relocations[SectionID].push_back(RE);
}
void RuntimeDyldImpl::addRelocationForSymbol(const RelocationEntry &RE,
StringRef SymbolName) {
// Relocation by symbol. If the symbol is found in the global symbol table,
// create an appropriate section relocation. Otherwise, add it to
// ExternalSymbolRelocations.
SymbolTableMap::const_iterator Loc =
GlobalSymbolTable.find(SymbolName);
if (Loc == GlobalSymbolTable.end()) {
ExternalSymbolRelocations[SymbolName].push_back(RE);
} else {
// Copy the RE since we want to modify its addend.
RelocationEntry RECopy = RE;
RECopy.Addend += Loc->second.second;
Relocations[Loc->second.first].push_back(RECopy);
}
}
uint8_t *RuntimeDyldImpl::createStubFunction(uint8_t *Addr) {
if (Arch == Triple::aarch64) {
// This stub has to be able to access the full address space,
// since symbol lookup won't necessarily find a handy, in-range,
// PLT stub for functions which could be anywhere.
uint32_t *StubAddr = (uint32_t*)Addr;
// Stub can use ip0 (== x16) to calculate address
*StubAddr = 0xd2e00010; // movz ip0, #:abs_g3:<addr>
StubAddr++;
*StubAddr = 0xf2c00010; // movk ip0, #:abs_g2_nc:<addr>
StubAddr++;
*StubAddr = 0xf2a00010; // movk ip0, #:abs_g1_nc:<addr>
StubAddr++;
*StubAddr = 0xf2800010; // movk ip0, #:abs_g0_nc:<addr>
StubAddr++;
*StubAddr = 0xd61f0200; // br ip0
return Addr;
} else if (Arch == Triple::arm) {
// TODO: There is only ARM far stub now. We should add the Thumb stub,
// and stubs for branches Thumb - ARM and ARM - Thumb.
uint32_t *StubAddr = (uint32_t*)Addr;
*StubAddr = 0xe51ff004; // ldr pc,<label>
return (uint8_t*)++StubAddr;
} else if (Arch == Triple::mipsel || Arch == Triple::mips) {
uint32_t *StubAddr = (uint32_t*)Addr;
// 0: 3c190000 lui t9,%hi(addr).
// 4: 27390000 addiu t9,t9,%lo(addr).
// 8: 03200008 jr t9.
// c: 00000000 nop.
const unsigned LuiT9Instr = 0x3c190000, AdduiT9Instr = 0x27390000;
const unsigned JrT9Instr = 0x03200008, NopInstr = 0x0;
*StubAddr = LuiT9Instr;
StubAddr++;
*StubAddr = AdduiT9Instr;
StubAddr++;
*StubAddr = JrT9Instr;
StubAddr++;
*StubAddr = NopInstr;
return Addr;
} else if (Arch == Triple::ppc64 || Arch == Triple::ppc64le) {
// PowerPC64 stub: the address points to a function descriptor
// instead of the function itself. Load the function address
// on r11 and sets it to control register. Also loads the function
// TOC in r2 and environment pointer to r11.
writeInt32BE(Addr, 0x3D800000); // lis r12, highest(addr)
writeInt32BE(Addr+4, 0x618C0000); // ori r12, higher(addr)
writeInt32BE(Addr+8, 0x798C07C6); // sldi r12, r12, 32
writeInt32BE(Addr+12, 0x658C0000); // oris r12, r12, h(addr)
writeInt32BE(Addr+16, 0x618C0000); // ori r12, r12, l(addr)
writeInt32BE(Addr+20, 0xF8410028); // std r2, 40(r1)
writeInt32BE(Addr+24, 0xE96C0000); // ld r11, 0(r12)
writeInt32BE(Addr+28, 0xE84C0008); // ld r2, 0(r12)
writeInt32BE(Addr+32, 0x7D6903A6); // mtctr r11
writeInt32BE(Addr+36, 0xE96C0010); // ld r11, 16(r2)
writeInt32BE(Addr+40, 0x4E800420); // bctr
return Addr;
} else if (Arch == Triple::systemz) {
writeInt16BE(Addr, 0xC418); // lgrl %r1,.+8
writeInt16BE(Addr+2, 0x0000);
writeInt16BE(Addr+4, 0x0004);
writeInt16BE(Addr+6, 0x07F1); // brc 15,%r1
// 8-byte address stored at Addr + 8
return Addr;
}
return Addr;
}
// Assign an address to a symbol name and resolve all the relocations
// associated with it.
void RuntimeDyldImpl::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. Relocations can't
// be applied until all the sections have been moved. The client must
// trigger this with a call to MCJIT::finalize() or
// RuntimeDyld::resolveRelocations().
//
// 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.
Sections[SectionID].LoadAddress = Addr;
}
void RuntimeDyldImpl::resolveRelocationList(const RelocationList &Relocs,
uint64_t Value) {
for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
const RelocationEntry &RE = Relocs[i];
// Ignore relocations for sections that were not loaded
if (Sections[RE.SectionID].Address == 0)
continue;
resolveRelocation(RE, Value);
}
}
void RuntimeDyldImpl::resolveExternalSymbols() {
StringMap<RelocationList>::iterator i = ExternalSymbolRelocations.begin(),
e = ExternalSymbolRelocations.end();
for (; i != e; i++) {
StringRef Name = i->first();
RelocationList &Relocs = i->second;
SymbolTableMap::const_iterator Loc = GlobalSymbolTable.find(Name);
if (Loc == GlobalSymbolTable.end()) {
if (Name.size() == 0) {
// This is an absolute symbol, use an address of zero.
DEBUG(dbgs() << "Resolving absolute relocations." << "\n");
resolveRelocationList(Relocs, 0);
} else {
// This is an external symbol, try to get its address from
// MemoryManager.
uint8_t *Addr = (uint8_t*) MemMgr->getPointerToNamedFunction(Name.data(),
true);
DEBUG(dbgs() << "Resolving relocations Name: " << Name
<< "\t" << format("%p", Addr)
<< "\n");
resolveRelocationList(Relocs, (uintptr_t)Addr);
}
} else {
report_fatal_error("Expected external symbol");
}
}
}
//===----------------------------------------------------------------------===//
// RuntimeDyld class implementation
RuntimeDyld::RuntimeDyld(RTDyldMemoryManager *mm) {
// FIXME: There's a potential issue lurking here if a single instance of
// RuntimeDyld is used to load multiple objects. The current implementation
// associates a single memory manager with a RuntimeDyld instance. Even
// though the public class spawns a new 'impl' instance for each load,
// they share a single memory manager. This can become a problem when page
// permissions are applied.
Dyld = 0;
MM = mm;
}
RuntimeDyld::~RuntimeDyld() {
delete Dyld;
}
ObjectImage *RuntimeDyld::loadObject(ObjectBuffer *InputBuffer) {
if (!Dyld) {
sys::fs::file_magic Type =
sys::fs::identify_magic(InputBuffer->getBuffer());
switch (Type) {
case sys::fs::file_magic::elf_relocatable:
case sys::fs::file_magic::elf_executable:
case sys::fs::file_magic::elf_shared_object:
case sys::fs::file_magic::elf_core:
Dyld = new RuntimeDyldELF(MM);
break;
case sys::fs::file_magic::macho_object:
case sys::fs::file_magic::macho_executable:
case sys::fs::file_magic::macho_fixed_virtual_memory_shared_lib:
case sys::fs::file_magic::macho_core:
case sys::fs::file_magic::macho_preload_executable:
case sys::fs::file_magic::macho_dynamically_linked_shared_lib:
case sys::fs::file_magic::macho_dynamic_linker:
case sys::fs::file_magic::macho_bundle:
case sys::fs::file_magic::macho_dynamically_linked_shared_lib_stub:
case sys::fs::file_magic::macho_dsym_companion:
Dyld = new RuntimeDyldMachO(MM);
break;
case sys::fs::file_magic::unknown:
case sys::fs::file_magic::bitcode:
case sys::fs::file_magic::archive:
case sys::fs::file_magic::coff_object:
case sys::fs::file_magic::pecoff_executable:
case sys::fs::file_magic::macho_universal_binary:
report_fatal_error("Incompatible object format!");
}
} else {
if (!Dyld->isCompatibleFormat(InputBuffer))
report_fatal_error("Incompatible object format!");
}
return Dyld->loadObject(InputBuffer);
}
void *RuntimeDyld::getSymbolAddress(StringRef Name) {
return Dyld->getSymbolAddress(Name);
}
uint64_t RuntimeDyld::getSymbolLoadAddress(StringRef Name) {
return Dyld->getSymbolLoadAddress(Name);
}
void RuntimeDyld::resolveRelocations() {
Dyld->resolveRelocations();
}
void RuntimeDyld::reassignSectionAddress(unsigned SectionID,
uint64_t Addr) {
Dyld->reassignSectionAddress(SectionID, Addr);
}
void RuntimeDyld::mapSectionAddress(const void *LocalAddress,
uint64_t TargetAddress) {
Dyld->mapSectionAddress(LocalAddress, TargetAddress);
}
StringRef RuntimeDyld::getErrorString() {
return Dyld->getErrorString();
}
StringRef RuntimeDyld::getEHFrameSection() {
return Dyld->getEHFrameSection();
}
} // end namespace llvm