| //===- FragmentLinker.cpp -------------------------------------------------===// |
| // |
| // The MCLinker Project |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the FragmentLinker class |
| // |
| //===----------------------------------------------------------------------===// |
| #include <mcld/Fragment/FragmentLinker.h> |
| |
| #include <llvm/Support/Host.h> |
| #include <llvm/Support/raw_ostream.h> |
| #include <llvm/Support/Casting.h> |
| |
| #include <mcld/LinkerConfig.h> |
| #include <mcld/Module.h> |
| #include <mcld/MC/MCLDInput.h> |
| #include <mcld/LD/BranchIslandFactory.h> |
| #include <mcld/LD/Resolver.h> |
| #include <mcld/LD/LDContext.h> |
| #include <mcld/LD/RelocationFactory.h> |
| #include <mcld/LD/RelocData.h> |
| #include <mcld/LD/SectionRules.h> |
| #include <mcld/Support/MemoryRegion.h> |
| #include <mcld/Support/MemoryArea.h> |
| #include <mcld/Support/FileHandle.h> |
| #include <mcld/Support/MsgHandling.h> |
| #include <mcld/Target/TargetLDBackend.h> |
| #include <mcld/Fragment/Relocation.h> |
| |
| using namespace mcld; |
| |
| //===----------------------------------------------------------------------===// |
| // FragmentLinker |
| //===----------------------------------------------------------------------===// |
| /// Constructor |
| FragmentLinker::FragmentLinker(const LinkerConfig& pConfig, |
| Module& pModule, |
| TargetLDBackend& pBackend) |
| |
| : m_Config(pConfig), |
| m_Module(pModule), |
| m_Backend(pBackend) { |
| } |
| |
| /// Destructor |
| FragmentLinker::~FragmentLinker() |
| { |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Symbol Operations |
| //===----------------------------------------------------------------------===// |
| /// defineSymbolForcefully - define an output symbol and override it immediately |
| LDSymbol* FragmentLinker::defineSymbolForcefully(const llvm::StringRef& pName, |
| bool pIsDyn, |
| ResolveInfo::Type pType, |
| ResolveInfo::Desc pDesc, |
| ResolveInfo::Binding pBinding, |
| ResolveInfo::SizeType pSize, |
| LDSymbol::ValueType pValue, |
| FragmentRef* pFragmentRef, |
| ResolveInfo::Visibility pVisibility) |
| { |
| ResolveInfo* info = m_Module.getNamePool().findInfo(pName); |
| LDSymbol* output_sym = NULL; |
| if (NULL == info) { |
| // the symbol is not in the pool, create a new one. |
| // create a ResolveInfo |
| Resolver::Result result; |
| m_Module.getNamePool().insertSymbol(pName, pIsDyn, pType, pDesc, |
| pBinding, pSize, pVisibility, |
| NULL, result); |
| assert(!result.existent); |
| |
| // create a output LDSymbol |
| output_sym = LDSymbol::Create(*result.info); |
| result.info->setSymPtr(output_sym); |
| |
| if (shouldForceLocal(*result.info)) |
| m_Module.getSymbolTable().forceLocal(*output_sym); |
| else |
| m_Module.getSymbolTable().add(*output_sym); |
| } |
| else { |
| // the symbol is already in the pool, override it |
| ResolveInfo old_info; |
| old_info.override(*info); |
| |
| info->setSource(pIsDyn); |
| info->setType(pType); |
| info->setDesc(pDesc); |
| info->setBinding(pBinding); |
| info->setVisibility(pVisibility); |
| info->setIsSymbol(true); |
| info->setSize(pSize); |
| |
| output_sym = info->outSymbol(); |
| if (NULL != output_sym) |
| m_Module.getSymbolTable().arrange(*output_sym, old_info); |
| else { |
| // create a output LDSymbol |
| output_sym = LDSymbol::Create(*info); |
| info->setSymPtr(output_sym); |
| |
| m_Module.getSymbolTable().add(*output_sym); |
| } |
| } |
| |
| if (NULL != output_sym) { |
| output_sym->setFragmentRef(pFragmentRef); |
| output_sym->setValue(pValue); |
| } |
| |
| return output_sym; |
| } |
| |
| /// defineSymbolAsRefered - define an output symbol and override it immediately |
| LDSymbol* FragmentLinker::defineSymbolAsRefered(const llvm::StringRef& pName, |
| bool pIsDyn, |
| ResolveInfo::Type pType, |
| ResolveInfo::Desc pDesc, |
| ResolveInfo::Binding pBinding, |
| ResolveInfo::SizeType pSize, |
| LDSymbol::ValueType pValue, |
| FragmentRef* pFragmentRef, |
| ResolveInfo::Visibility pVisibility) |
| { |
| ResolveInfo* info = m_Module.getNamePool().findInfo(pName); |
| |
| if (NULL == info || !(info->isUndef() || info->isDyn())) { |
| // only undefined symbol and dynamic symbol can make a reference. |
| return NULL; |
| } |
| |
| // the symbol is already in the pool, override it |
| ResolveInfo old_info; |
| old_info.override(*info); |
| |
| info->setSource(pIsDyn); |
| info->setType(pType); |
| info->setDesc(pDesc); |
| info->setBinding(pBinding); |
| info->setVisibility(pVisibility); |
| info->setIsSymbol(true); |
| info->setSize(pSize); |
| |
| LDSymbol* output_sym = info->outSymbol(); |
| if (NULL != output_sym) { |
| output_sym->setFragmentRef(pFragmentRef); |
| output_sym->setValue(pValue); |
| m_Module.getSymbolTable().arrange(*output_sym, old_info); |
| } |
| else { |
| // create a output LDSymbol |
| output_sym = LDSymbol::Create(*info); |
| info->setSymPtr(output_sym); |
| |
| m_Module.getSymbolTable().add(*output_sym); |
| } |
| |
| return output_sym; |
| } |
| |
| /// defineAndResolveSymbolForcefully - define an output symbol and resolve it |
| /// immediately |
| LDSymbol* FragmentLinker::defineAndResolveSymbolForcefully(const llvm::StringRef& pName, |
| bool pIsDyn, |
| ResolveInfo::Type pType, |
| ResolveInfo::Desc pDesc, |
| ResolveInfo::Binding pBinding, |
| ResolveInfo::SizeType pSize, |
| LDSymbol::ValueType pValue, |
| FragmentRef* pFragmentRef, |
| ResolveInfo::Visibility pVisibility) |
| { |
| // Result is <info, existent, override> |
| Resolver::Result result; |
| ResolveInfo old_info; |
| m_Module.getNamePool().insertSymbol(pName, pIsDyn, pType, pDesc, pBinding, |
| pSize, pVisibility, |
| &old_info, result); |
| |
| LDSymbol* output_sym = result.info->outSymbol(); |
| bool has_output_sym = (NULL != output_sym); |
| |
| if (!result.existent || !has_output_sym) { |
| output_sym = LDSymbol::Create(*result.info); |
| result.info->setSymPtr(output_sym); |
| } |
| |
| if (result.overriden || !has_output_sym) { |
| output_sym->setFragmentRef(pFragmentRef); |
| output_sym->setValue(pValue); |
| } |
| |
| // After symbol resolution, the visibility is changed to the most restrict. |
| // arrange the output position |
| if (shouldForceLocal(*result.info)) |
| m_Module.getSymbolTable().forceLocal(*output_sym); |
| else if (has_output_sym) |
| m_Module.getSymbolTable().arrange(*output_sym, old_info); |
| else |
| m_Module.getSymbolTable().add(*output_sym); |
| |
| return output_sym; |
| } |
| |
| /// defineAndResolveSymbolAsRefered - define an output symbol and resolve it |
| /// immediately. |
| LDSymbol* FragmentLinker::defineAndResolveSymbolAsRefered(const llvm::StringRef& pName, |
| bool pIsDyn, |
| ResolveInfo::Type pType, |
| ResolveInfo::Desc pDesc, |
| ResolveInfo::Binding pBinding, |
| ResolveInfo::SizeType pSize, |
| LDSymbol::ValueType pValue, |
| FragmentRef* pFragmentRef, |
| ResolveInfo::Visibility pVisibility) |
| { |
| ResolveInfo* info = m_Module.getNamePool().findInfo(pName); |
| |
| if (NULL == info || !(info->isUndef() || info->isDyn())) { |
| // only undefined symbol and dynamic symbol can make a reference. |
| return NULL; |
| } |
| |
| return defineAndResolveSymbolForcefully(pName, |
| pIsDyn, |
| pType, |
| pDesc, |
| pBinding, |
| pSize, |
| pValue, |
| pFragmentRef, |
| pVisibility); |
| } |
| |
| bool FragmentLinker::finalizeSymbols() |
| { |
| Module::sym_iterator symbol, symEnd = m_Module.sym_end(); |
| for (symbol = m_Module.sym_begin(); symbol != symEnd; ++symbol) { |
| |
| if ((*symbol)->resolveInfo()->isAbsolute() || |
| (*symbol)->resolveInfo()->type() == ResolveInfo::File) { |
| // absolute symbols or symbols with function type should have |
| // zero value |
| (*symbol)->setValue(0x0); |
| continue; |
| } |
| |
| if ((*symbol)->resolveInfo()->type() == ResolveInfo::ThreadLocal) { |
| m_Backend.finalizeTLSSymbol(**symbol); |
| continue; |
| } |
| |
| if ((*symbol)->hasFragRef()) { |
| // set the virtual address of the symbol. If the output file is |
| // relocatable object file, the section's virtual address becomes zero. |
| // And the symbol's value become section relative offset. |
| uint64_t value = (*symbol)->fragRef()->getOutputOffset(); |
| assert(NULL != (*symbol)->fragRef()->frag()); |
| uint64_t addr = (*symbol)->fragRef()->frag()->getParent()->getSection().addr(); |
| (*symbol)->setValue(value + addr); |
| continue; |
| } |
| } |
| |
| // finialize target-dependent symbols |
| return m_Backend.finalizeSymbols(*this); |
| } |
| |
| bool FragmentLinker::shouldForceLocal(const ResolveInfo& pInfo) const |
| { |
| // forced local symbol matches all rules: |
| // 1. We are not doing incremental linking. |
| // 2. The symbol is with Hidden or Internal visibility. |
| // 3. The symbol should be global or weak. Otherwise, local symbol is local. |
| // 4. The symbol is defined or common |
| if (LinkerConfig::Object != m_Config.codeGenType() && |
| (pInfo.visibility() == ResolveInfo::Hidden || |
| pInfo.visibility() == ResolveInfo::Internal) && |
| (pInfo.isGlobal() || pInfo.isWeak()) && |
| (pInfo.isDefine() || pInfo.isCommon())) |
| return true; |
| return false; |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Relocation Operations |
| //===----------------------------------------------------------------------===// |
| bool FragmentLinker::applyRelocations() |
| { |
| // when producing relocatables, no need to apply relocation |
| if (LinkerConfig::Object == m_Config.codeGenType()) |
| return true; |
| |
| // apply all relocations of all inputs |
| Module::obj_iterator input, inEnd = m_Module.obj_end(); |
| for (input = m_Module.obj_begin(); input != inEnd; ++input) { |
| LDContext::sect_iterator rs, rsEnd = (*input)->context()->relocSectEnd(); |
| for (rs = (*input)->context()->relocSectBegin(); rs != rsEnd; ++rs) { |
| // bypass the reloc section if |
| // 1. its section kind is changed to Ignore. (The target section is a |
| // discarded group section.) |
| // 2. it has no reloc data. (All symbols in the input relocs are in the |
| // discarded group sections) |
| if (LDFileFormat::Ignore == (*rs)->kind() || !(*rs)->hasRelocData()) |
| continue; |
| RelocData::iterator reloc, rEnd = (*rs)->getRelocData()->end(); |
| for (reloc = (*rs)->getRelocData()->begin(); reloc != rEnd; ++reloc) { |
| Relocation* relocation = llvm::cast<Relocation>(reloc); |
| relocation->apply(*m_Backend.getRelocator()); |
| } // for all relocations |
| } // for all relocation section |
| } // for all inputs |
| |
| // apply relocations created by relaxation |
| BranchIslandFactory* br_factory = m_Backend.getBRIslandFactory(); |
| BranchIslandFactory::iterator facIter, facEnd = br_factory->end(); |
| for (facIter = br_factory->begin(); facIter != facEnd; ++facIter) { |
| BranchIsland& island = *facIter; |
| BranchIsland::reloc_iterator iter, iterEnd = island.reloc_end(); |
| for (iter = island.reloc_begin(); iter != iterEnd; ++iter) |
| (*iter)->apply(*m_Backend.getRelocator()); |
| } |
| return true; |
| } |
| |
| |
| void FragmentLinker::syncRelocationResult(MemoryArea& pOutput) |
| { |
| if (LinkerConfig::Object != m_Config.codeGenType()) |
| normalSyncRelocationResult(pOutput); |
| else |
| partialSyncRelocationResult(pOutput); |
| return; |
| } |
| |
| void FragmentLinker::normalSyncRelocationResult(MemoryArea& pOutput) |
| { |
| MemoryRegion* region = pOutput.request(0, pOutput.handler()->size()); |
| |
| uint8_t* data = region->getBuffer(); |
| |
| // sync all relocations of all inputs |
| Module::obj_iterator input, inEnd = m_Module.obj_end(); |
| for (input = m_Module.obj_begin(); input != inEnd; ++input) { |
| LDContext::sect_iterator rs, rsEnd = (*input)->context()->relocSectEnd(); |
| for (rs = (*input)->context()->relocSectBegin(); rs != rsEnd; ++rs) { |
| // bypass the reloc section if |
| // 1. its section kind is changed to Ignore. (The target section is a |
| // discarded group section.) |
| // 2. it has no reloc data. (All symbols in the input relocs are in the |
| // discarded group sections) |
| if (LDFileFormat::Ignore == (*rs)->kind() || !(*rs)->hasRelocData()) |
| continue; |
| RelocData::iterator reloc, rEnd = (*rs)->getRelocData()->end(); |
| for (reloc = (*rs)->getRelocData()->begin(); reloc != rEnd; ++reloc) { |
| Relocation* relocation = llvm::cast<Relocation>(reloc); |
| |
| // bypass the relocation with NONE type. This is to avoid overwrite the |
| // target result by NONE type relocation if there is a place which has |
| // two relocations to apply to, and one of it is NONE type. The result |
| // we want is the value of the other relocation result. For example, |
| // in .exidx, there are usually an R_ARM_NONE and R_ARM_PREL31 apply to |
| // the same place |
| if (0x0 == relocation->type()) |
| continue; |
| writeRelocationResult(*relocation, data); |
| } // for all relocations |
| } // for all relocation section |
| } // for all inputs |
| |
| // sync relocations created by relaxation |
| BranchIslandFactory* br_factory = m_Backend.getBRIslandFactory(); |
| BranchIslandFactory::iterator facIter, facEnd = br_factory->end(); |
| for (facIter = br_factory->begin(); facIter != facEnd; ++facIter) { |
| BranchIsland& island = *facIter; |
| BranchIsland::reloc_iterator iter, iterEnd = island.reloc_end(); |
| for (iter = island.reloc_begin(); iter != iterEnd; ++iter) { |
| Relocation* reloc = *iter; |
| writeRelocationResult(*reloc, data); |
| } |
| } |
| |
| pOutput.clear(); |
| } |
| |
| void FragmentLinker::partialSyncRelocationResult(MemoryArea& pOutput) |
| { |
| MemoryRegion* region = pOutput.request(0, pOutput.handler()->size()); |
| |
| uint8_t* data = region->getBuffer(); |
| |
| // traverse outputs' LDSection to get RelocData |
| Module::iterator sectIter, sectEnd = m_Module.end(); |
| for (sectIter = m_Module.begin(); sectIter != sectEnd; ++sectIter) { |
| if (LDFileFormat::Relocation != (*sectIter)->kind()) |
| continue; |
| |
| RelocData* reloc_data = (*sectIter)->getRelocData(); |
| RelocData::iterator relocIter, relocEnd = reloc_data->end(); |
| for (relocIter = reloc_data->begin(); relocIter != relocEnd; ++relocIter) { |
| Relocation* reloc = llvm::cast<Relocation>(relocIter); |
| |
| // bypass the relocation with NONE type. This is to avoid overwrite the |
| // target result by NONE type relocation if there is a place which has |
| // two relocations to apply to, and one of it is NONE type. The result |
| // we want is the value of the other relocation result. For example, |
| // in .exidx, there are usually an R_ARM_NONE and R_ARM_PREL31 apply to |
| // the same place |
| if (0x0 == reloc->type()) |
| continue; |
| writeRelocationResult(*reloc, data); |
| } |
| } |
| |
| pOutput.clear(); |
| } |
| |
| void FragmentLinker::writeRelocationResult(Relocation& pReloc, uint8_t* pOutput) |
| { |
| // get output file offset |
| size_t out_offset = pReloc.targetRef().frag()->getParent()->getSection().offset() + |
| pReloc.targetRef().getOutputOffset(); |
| |
| uint8_t* target_addr = pOutput + out_offset; |
| // byte swapping if target and host has different endian, and then write back |
| if(llvm::sys::isLittleEndianHost() != m_Config.targets().isLittleEndian()) { |
| uint64_t tmp_data = 0; |
| |
| switch(m_Config.targets().bitclass()) { |
| case 32u: |
| tmp_data = mcld::bswap32(pReloc.target()); |
| std::memcpy(target_addr, &tmp_data, 4); |
| break; |
| |
| case 64u: |
| tmp_data = mcld::bswap64(pReloc.target()); |
| std::memcpy(target_addr, &tmp_data, 8); |
| break; |
| |
| default: |
| break; |
| } |
| } |
| else |
| std::memcpy(target_addr, &pReloc.target(), m_Config.targets().bitclass()/8); |
| } |
| |
| /// isOutputPIC - return whether the output is position-independent |
| bool FragmentLinker::isOutputPIC() const |
| { |
| return checkIsOutputPIC(); |
| } |
| |
| /// isStaticLink - return whether we're doing static link |
| bool FragmentLinker::isStaticLink() const |
| { |
| return checkIsStaticLink(); |
| } |
| |
| bool FragmentLinker::checkIsOutputPIC() const |
| { |
| if (LinkerConfig::DynObj == m_Config.codeGenType() || |
| m_Config.options().isPIE()) |
| return true; |
| return false; |
| } |
| |
| bool FragmentLinker::checkIsStaticLink() const |
| { |
| if (m_Module.getLibraryList().empty() && !isOutputPIC()) |
| return true; |
| return false; |
| } |
| |
