//===- X86Relocator.cpp -------------------------------------------===//
//
// The MCLinker Project
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "X86Relocator.h"
#include "X86RelocationFunctions.h"
#include <mcld/LinkerConfig.h>
#include <mcld/IRBuilder.h>
#include <mcld/Support/MsgHandling.h>
#include <mcld/LD/LDSymbol.h>
#include <mcld/Object/ObjectBuilder.h>
#include <llvm/ADT/Twine.h>
#include <llvm/Support/DataTypes.h>
#include <llvm/Support/ELF.h>
using namespace mcld;
//===--------------------------------------------------------------------===//
// Relocation Functions and Tables
//===--------------------------------------------------------------------===//
DECL_X86_32_APPLY_RELOC_FUNCS
/// the prototype of applying function
typedef Relocator::Result (*X86_32ApplyFunctionType)(Relocation& pReloc,
X86_32Relocator& pParent);
// the table entry of applying functions
struct X86_32ApplyFunctionTriple
{
X86_32ApplyFunctionType func;
unsigned int type;
const char* name;
unsigned int size;
};
// declare the table of applying functions
static const X86_32ApplyFunctionTriple X86_32ApplyFunctions[] = {
DECL_X86_32_APPLY_RELOC_FUNC_PTRS
};
//===--------------------------------------------------------------------===//
// X86Relocator
//===--------------------------------------------------------------------===//
X86Relocator::X86Relocator(const LinkerConfig& pConfig)
: Relocator(pConfig) {
}
X86Relocator::~X86Relocator()
{
}
void X86Relocator::scanRelocation(Relocation& pReloc,
IRBuilder& pLinker,
Module& pModule,
LDSection& pSection)
{
if (LinkerConfig::Object == config().codeGenType())
return;
// rsym - The relocation target symbol
ResolveInfo* rsym = pReloc.symInfo();
assert(NULL != rsym &&
"ResolveInfo of relocation not set while scanRelocation");
pReloc.updateAddend();
assert(NULL != pSection.getLink());
if (0 == (pSection.getLink()->flag() & llvm::ELF::SHF_ALLOC))
return;
// Scan relocation type to determine if the GOT/PLT/Dynamic Relocation
// entries should be created.
if (rsym->isLocal()) // rsym is local
scanLocalReloc(pReloc, pLinker, pModule, pSection);
else // rsym is external
scanGlobalReloc(pReloc, pLinker, pModule, pSection);
// check if we should issue undefined reference for the relocation target
// symbol
if (rsym->isUndef() && !rsym->isDyn() && !rsym->isWeak() && !rsym->isNull())
fatal(diag::undefined_reference) << rsym->name();
}
void X86Relocator::addCopyReloc(ResolveInfo& pSym, X86GNULDBackend& pTarget)
{
Relocation& rel_entry = *pTarget.getRelDyn().consumeEntry();
rel_entry.setType(pTarget.getCopyRelType());
assert(pSym.outSymbol()->hasFragRef());
rel_entry.targetRef().assign(*pSym.outSymbol()->fragRef());
rel_entry.setSymInfo(&pSym);
}
/// defineSymbolforCopyReloc
/// For a symbol needing copy relocation, define a copy symbol in the BSS
/// section and all other reference to this symbol should refer to this
/// copy.
/// @note This is executed at `scan relocation' stage.
LDSymbol& X86Relocator::defineSymbolforCopyReloc(IRBuilder& pBuilder,
const ResolveInfo& pSym,
X86GNULDBackend& pTarget)
{
// get or create corresponding BSS LDSection
LDSection* bss_sect_hdr = NULL;
ELFFileFormat* file_format = pTarget.getOutputFormat();
if (ResolveInfo::ThreadLocal == pSym.type())
bss_sect_hdr = &file_format->getTBSS();
else
bss_sect_hdr = &file_format->getBSS();
// get or create corresponding BSS SectionData
assert(NULL != bss_sect_hdr);
SectionData* bss_section = NULL;
if (bss_sect_hdr->hasSectionData())
bss_section = bss_sect_hdr->getSectionData();
else
bss_section = IRBuilder::CreateSectionData(*bss_sect_hdr);
// Determine the alignment by the symbol value
// FIXME: here we use the largest alignment
uint32_t addralign = config().targets().bitclass() / 8;
// allocate space in BSS for the copy symbol
Fragment* frag = new FillFragment(0x0, 1, pSym.size());
uint64_t size = ObjectBuilder::AppendFragment(*frag,
*bss_section,
addralign);
bss_sect_hdr->setSize(bss_sect_hdr->size() + size);
// change symbol binding to Global if it's a weak symbol
ResolveInfo::Binding binding = (ResolveInfo::Binding)pSym.binding();
if (binding == ResolveInfo::Weak)
binding = ResolveInfo::Global;
// Define the copy symbol in the bss section and resolve it
LDSymbol* cpy_sym = pBuilder.AddSymbol<IRBuilder::Force, IRBuilder::Resolve>(
pSym.name(),
(ResolveInfo::Type)pSym.type(),
ResolveInfo::Define,
binding,
pSym.size(), // size
0x0, // value
FragmentRef::Create(*frag, 0x0),
(ResolveInfo::Visibility)pSym.other());
// output all other alias symbols if any
Module &pModule = pBuilder.getModule();
Module::AliasList* alias_list = pModule.getAliasList(pSym);
if (NULL!=alias_list) {
Module::alias_iterator it, it_e=alias_list->end();
for (it=alias_list->begin(); it!=it_e; ++it) {
const ResolveInfo* alias = *it;
if (alias!=&pSym && alias->isDyn()) {
pBuilder.AddSymbol<IRBuilder::Force, IRBuilder::Resolve>(
alias->name(),
(ResolveInfo::Type)alias->type(),
ResolveInfo::Define,
binding,
alias->size(), // size
0x0, // value
FragmentRef::Create(*frag, 0x0),
(ResolveInfo::Visibility)alias->other());
}
}
}
return *cpy_sym;
}
//===--------------------------------------------------------------------===//
// X86_32Relocator
//===--------------------------------------------------------------------===//
X86_32Relocator::X86_32Relocator(X86_32GNULDBackend& pParent,
const LinkerConfig& pConfig)
: X86Relocator(pConfig), m_Target(pParent) {
}
Relocator::Result
X86_32Relocator::applyRelocation(Relocation& pRelocation)
{
Relocation::Type type = pRelocation.type();
if (type >= sizeof (X86_32ApplyFunctions) / sizeof (X86_32ApplyFunctions[0]) ) {
return Unknown;
}
// apply the relocation
return X86_32ApplyFunctions[type].func(pRelocation, *this);
}
const char* X86_32Relocator::getName(Relocation::Type pType) const
{
return X86_32ApplyFunctions[pType].name;
}
Relocator::Size X86_32Relocator::getSize(Relocation::Type pType) const
{
return X86_32ApplyFunctions[pType].size;;
}
void X86_32Relocator::scanLocalReloc(Relocation& pReloc,
IRBuilder& pBuilder,
Module& pModule,
LDSection& pSection)
{
// rsym - The relocation target symbol
ResolveInfo* rsym = pReloc.symInfo();
switch(pReloc.type()){
case llvm::ELF::R_386_32:
case llvm::ELF::R_386_16:
case llvm::ELF::R_386_8:
// If buiding PIC object (shared library or PIC executable),
// a dynamic relocations with RELATIVE type to this location is needed.
// Reserve an entry in .rel.dyn
if (config().isCodeIndep()) {
getTarget().getRelDyn().reserveEntry();
// set Rel bit
rsym->setReserved(rsym->reserved() | ReserveRel);
getTarget().checkAndSetHasTextRel(*pSection.getLink());
}
return;
case llvm::ELF::R_386_PLT32:
return;
case llvm::ELF::R_386_GOTOFF:
case llvm::ELF::R_386_GOTPC:
// FIXME: A GOT section is needed
return;
case llvm::ELF::R_386_GOT32:
// Symbol needs GOT entry, reserve entry in .got
// return if we already create GOT for this symbol
if (rsym->reserved() & (ReserveGOT | GOTRel))
return;
// FIXME: check STT_GNU_IFUNC symbol
getTarget().getGOT().reserve();
// If the GOT is used in statically linked binaries,
// the GOT entry is enough and no relocation is needed.
if (config().isCodeStatic()) {
rsym->setReserved(rsym->reserved() | ReserveGOT);
return;
}
// If building shared object or the symbol is undefined, a dynamic
// relocation is needed to relocate this GOT entry. Reserve an
// entry in .rel.dyn
if (LinkerConfig::DynObj ==
config().codeGenType() || rsym->isUndef() || rsym->isDyn()) {
getTarget().getRelDyn().reserveEntry();
// set GOTRel bit
rsym->setReserved(rsym->reserved() | GOTRel);
return;
}
// set GOT bit
rsym->setReserved(rsym->reserved() | ReserveGOT);
return;
case llvm::ELF::R_386_PC32:
case llvm::ELF::R_386_PC16:
case llvm::ELF::R_386_PC8:
return;
case llvm::ELF::R_386_TLS_GD: {
// FIXME: no linker optimization for TLS relocation
if (rsym->reserved() & GOTRel)
return;
getTarget().getGOT().reserve(2);
// reserve an rel entry
getTarget().getRelDyn().reserveEntry();
// set GOTRel bit
rsym->setReserved(rsym->reserved() | GOTRel);
// define the section symbol for .tdata or .tbss
// the target symbol of the created dynamic relocation should be the
// section symbol of the section which this symbol defined. so we
// need to define that section symbol here
ELFFileFormat* file_format = getTarget().getOutputFormat();
const LDSection* sym_sect =
&rsym->outSymbol()->fragRef()->frag()->getParent()->getSection();
if (&file_format->getTData() == sym_sect) {
if (!getTarget().hasTDATASymbol())
getTarget().setTDATASymbol(*pModule.getSectionSymbolSet().get(*sym_sect));
}
else if (&file_format->getTBSS() == sym_sect || rsym->isCommon()) {
if (!getTarget().hasTBSSSymbol())
getTarget().setTBSSSymbol(*pModule.getSectionSymbolSet().get(*sym_sect));
}
else
error(diag::invalid_tls) << rsym->name() << sym_sect->name();
return;
}
case llvm::ELF::R_386_TLS_LDM:
getTLSModuleID();
return;
case llvm::ELF::R_386_TLS_LDO_32:
return;
case llvm::ELF::R_386_TLS_IE:
getTarget().setHasStaticTLS();
// if buildint shared object, a RELATIVE dynamic relocation is needed
if (LinkerConfig::DynObj == config().codeGenType()) {
getTarget().getRelDyn().reserveEntry();
rsym->setReserved(rsym->reserved() | ReserveRel);
getTarget().checkAndSetHasTextRel(*pSection.getLink());
} else {
// for local sym, we can convert ie to le if not building shared object
convertTLSIEtoLE(pReloc, pSection);
return;
}
if (rsym->reserved() & GOTRel)
return;
// reserve got and dyn relocation entries for tp-relative offset
getTarget().getGOT().reserve();
getTarget().getRelDyn().reserveEntry();
// set GOTRel bit
rsym->setReserved(rsym->reserved() | GOTRel);
getTarget().getRelDyn().addSymbolToDynSym(*rsym->outSymbol());
return;
case llvm::ELF::R_386_TLS_GOTIE:
getTarget().setHasStaticTLS();
if (rsym->reserved() & GOTRel)
return;
// reserve got and dyn relocation entries for tp-relative offset
getTarget().getGOT().reserve();
getTarget().getRelDyn().reserveEntry();
// set GOTRel bit
rsym->setReserved(rsym->reserved() | GOTRel);
getTarget().getRelDyn().addSymbolToDynSym(*rsym->outSymbol());
return;
case llvm::ELF::R_386_TLS_LE:
case llvm::ELF::R_386_TLS_LE_32:
getTarget().setHasStaticTLS();
// if buildint shared object, a dynamic relocation is needed
if (LinkerConfig::DynObj == config().codeGenType()) {
getTarget().getRelDyn().reserveEntry();
rsym->setReserved(rsym->reserved() | ReserveRel);
getTarget().checkAndSetHasTextRel(*pSection.getLink());
// the target symbol of the dynamic relocation is rsym, so we need to
// emit it into .dynsym
assert(NULL != rsym->outSymbol());
getTarget().getRelDyn().addSymbolToDynSym(*rsym->outSymbol());
}
return;
default:
fatal(diag::unsupported_relocation) << (int)pReloc.type()
<< "mclinker@googlegroups.com";
break;
} // end switch
}
void X86_32Relocator::scanGlobalReloc(Relocation& pReloc,
IRBuilder& pBuilder,
Module& pModule,
LDSection& pSection)
{
// rsym - The relocation target symbol
ResolveInfo* rsym = pReloc.symInfo();
switch(pReloc.type()) {
case llvm::ELF::R_386_32:
case llvm::ELF::R_386_16:
case llvm::ELF::R_386_8:
// Absolute relocation type, symbol may needs PLT entry or
// dynamic relocation entry
if (getTarget().symbolNeedsPLT(*rsym)) {
// create plt for this symbol if it does not have one
if (!(rsym->reserved() & ReservePLT)){
// Symbol needs PLT entry, we need to reserve a PLT entry
// and the corresponding GOT and dynamic relocation entry
// in .got and .rel.plt. (GOT entry will be reserved simultaneously
// when calling X86PLT->reserveEntry())
getTarget().getPLT().reserveEntry();
getTarget().getGOTPLT().reserve();
getTarget().getRelPLT().reserveEntry();
// set PLT bit
rsym->setReserved(rsym->reserved() | ReservePLT);
}
}
if (getTarget().symbolNeedsDynRel(*rsym, (rsym->reserved() & ReservePLT), true)) {
// symbol needs dynamic relocation entry, reserve an entry in .rel.dyn
getTarget().getRelDyn().reserveEntry();
if (getTarget().symbolNeedsCopyReloc(pReloc, *rsym)) {
LDSymbol& cpy_sym = defineSymbolforCopyReloc(pBuilder, *rsym, getTarget());
addCopyReloc(*cpy_sym.resolveInfo(), getTarget());
}
else {
// set Rel bit
rsym->setReserved(rsym->reserved() | ReserveRel);
getTarget().checkAndSetHasTextRel(pSection);
}
}
return;
case llvm::ELF::R_386_GOTOFF:
case llvm::ELF::R_386_GOTPC: {
// FIXME: A GOT section is needed
return;
}
case llvm::ELF::R_386_PLT32:
// A PLT entry is needed when building shared library
// return if we already create plt for this symbol
if (rsym->reserved() & ReservePLT)
return;
// if the symbol's value can be decided at link time, then no need plt
if (getTarget().symbolFinalValueIsKnown(*rsym))
return;
// if symbol is defined in the ouput file and it's not
// preemptible, no need plt
if (rsym->isDefine() && !rsym->isDyn() &&
!getTarget().isSymbolPreemptible(*rsym)) {
return;
}
// Symbol needs PLT entry, we need to reserve a PLT entry
// and the corresponding GOT and dynamic relocation entry
// in .got and .rel.plt. (GOT entry will be reserved simultaneously
// when calling X86PLT->reserveEntry())
getTarget().getPLT().reserveEntry();
getTarget().getGOTPLT().reserve();
getTarget().getRelPLT().reserveEntry();
// set PLT bit
rsym->setReserved(rsym->reserved() | ReservePLT);
return;
case llvm::ELF::R_386_GOT32:
// Symbol needs GOT entry, reserve entry in .got
// return if we already create GOT for this symbol
if (rsym->reserved() & (ReserveGOT | GOTRel))
return;
getTarget().getGOT().reserve();
// If the GOT is used in statically linked binaries,
// the GOT entry is enough and no relocation is needed.
if (config().isCodeStatic()) {
rsym->setReserved(rsym->reserved() | ReserveGOT);
return;
}
// If building shared object or the symbol is undefined, a dynamic
// relocation is needed to relocate this GOT entry. Reserve an
// entry in .rel.dyn
if (LinkerConfig::DynObj ==
config().codeGenType() || rsym->isUndef() || rsym->isDyn()) {
getTarget().getRelDyn().reserveEntry();
// set GOTRel bit
rsym->setReserved(rsym->reserved() | GOTRel);
return;
}
// set GOT bit
rsym->setReserved(rsym->reserved() | ReserveGOT);
return;
case llvm::ELF::R_386_PC32:
case llvm::ELF::R_386_PC16:
case llvm::ELF::R_386_PC8:
if (getTarget().symbolNeedsPLT(*rsym) &&
LinkerConfig::DynObj != config().codeGenType()) {
// create plt for this symbol if it does not have one
if (!(rsym->reserved() & ReservePLT)){
// Symbol needs PLT entry, we need to reserve a PLT entry
// and the corresponding GOT and dynamic relocation entry
// in .got and .rel.plt. (GOT entry will be reserved simultaneously
// when calling X86PLT->reserveEntry())
getTarget().getPLT().reserveEntry();
getTarget().getGOTPLT().reserve();
getTarget().getRelPLT().reserveEntry();
// set PLT bit
rsym->setReserved(rsym->reserved() | ReservePLT);
}
}
if (getTarget().symbolNeedsDynRel(*rsym, (rsym->reserved() & ReservePLT), false)) {
// symbol needs dynamic relocation entry, reserve an entry in .rel.dyn
getTarget().getRelDyn().reserveEntry();
if (getTarget().symbolNeedsCopyReloc(pReloc, *rsym)) {
LDSymbol& cpy_sym = defineSymbolforCopyReloc(pBuilder, *rsym, getTarget());
addCopyReloc(*cpy_sym.resolveInfo(), getTarget());
}
else {
// set Rel bit
rsym->setReserved(rsym->reserved() | ReserveRel);
getTarget().checkAndSetHasTextRel(pSection);
}
}
return;
case llvm::ELF::R_386_TLS_GD: {
// FIXME: no linker optimization for TLS relocation
if (rsym->reserved() & GOTRel)
return;
// reserve two pairs of got entry and dynamic relocation
getTarget().getGOT().reserve(2);
getTarget().getRelDyn().reserveEntry(2);
getTarget().getRelDyn().addSymbolToDynSym(*rsym->outSymbol());
// set GOTRel bit
rsym->setReserved(rsym->reserved() | GOTRel);
return;
}
case llvm::ELF::R_386_TLS_LDM:
getTLSModuleID();
return;
case llvm::ELF::R_386_TLS_LDO_32:
return;
case llvm::ELF::R_386_TLS_IE:
getTarget().setHasStaticTLS();
// if buildint shared object, a RELATIVE dynamic relocation is needed
if (LinkerConfig::DynObj == config().codeGenType()) {
getTarget().getRelDyn().reserveEntry();
rsym->setReserved(rsym->reserved() | ReserveRel);
getTarget().checkAndSetHasTextRel(*pSection.getLink());
} else {
// for global sym, we can convert ie to le if its final value is known
if (getTarget().symbolFinalValueIsKnown(*rsym)) {
convertTLSIEtoLE(pReloc, pSection);
return;
}
}
if (rsym->reserved() & GOTRel)
return;
// reserve got and dyn relocation entries for tp-relative offset
getTarget().getGOT().reserve();
getTarget().getRelDyn().reserveEntry();
getTarget().getRelDyn().addSymbolToDynSym(*rsym->outSymbol());
// set GOTRel bit
rsym->setReserved(rsym->reserved() | GOTRel);
return;
case llvm::ELF::R_386_TLS_GOTIE:
getTarget().setHasStaticTLS();
if (rsym->reserved() & GOTRel)
return;
// reserve got and dyn relocation entries for tp-relative offset
getTarget().getGOT().reserve();
getTarget().getRelDyn().reserveEntry();
getTarget().getRelDyn().addSymbolToDynSym(*rsym->outSymbol());
// set GOTRel bit
rsym->setReserved(rsym->reserved() | GOTRel);
return;
case llvm::ELF::R_386_TLS_LE:
case llvm::ELF::R_386_TLS_LE_32:
getTarget().setHasStaticTLS();
// if buildint shared object, a dynamic relocation is needed
if (LinkerConfig::DynObj == config().codeGenType()) {
getTarget().getRelDyn().reserveEntry();
getTarget().getRelDyn().addSymbolToDynSym(*rsym->outSymbol());
rsym->setReserved(rsym->reserved() | ReserveRel);
getTarget().checkAndSetHasTextRel(*pSection.getLink());
}
return;
default: {
fatal(diag::unsupported_relocation) << (int)pReloc.type()
<< "mclinker@googlegroups.com";
break;
}
} // end switch
}
// Create a GOT entry for the TLS module index
X86_32GOTEntry& X86_32Relocator::getTLSModuleID()
{
static X86_32GOTEntry* got_entry = NULL;
if (NULL != got_entry)
return *got_entry;
// Allocate 2 got entries and 1 dynamic reloc for R_386_TLS_LDM
getTarget().getGOT().reserve(2);
got_entry = getTarget().getGOT().consume();
getTarget().getGOT().consume()->setValue(0x0);
getTarget().getRelDyn().reserveEntry();
Relocation* rel_entry = getTarget().getRelDyn().consumeEntry();
rel_entry->setType(llvm::ELF::R_386_TLS_DTPMOD32);
rel_entry->targetRef().assign(*got_entry, 0x0);
rel_entry->setSymInfo(NULL);
return *got_entry;
}
/// convert R_386_TLS_IE to R_386_TLS_LE
void X86_32Relocator::convertTLSIEtoLE(Relocation& pReloc,
LDSection& pSection)
{
assert(pReloc.type() == llvm::ELF::R_386_TLS_IE);
assert(NULL != pReloc.targetRef().frag());
// 1. create the fragment references and new relocs
uint64_t off = pReloc.targetRef().offset();
if (off >= 4)
off -= 4;
else
off = 0;
FragmentRef* fragref = FragmentRef::Create(*pReloc.targetRef().frag(), off);
// TODO: add symbols for R_386_TLS_OPT relocs
Relocation* reloc = Relocation::Create(X86_32Relocator::R_386_TLS_OPT,
*fragref,
0x0);
// 2. modify the opcodes to the appropriate ones
uint8_t* op = (reinterpret_cast<uint8_t*>(&reloc->target()));
off = pReloc.targetRef().offset() - reloc->targetRef().offset() - 1;
if (op[off] == 0xa1) {
op[off] = 0xb8;
} else {
switch (op[off - 1]) {
case 0x8b:
assert((op[off] & 0xc7) == 0x05);
op[off - 1] = 0xc7;
op[off] = 0xc0 | ((op[off] >> 3) & 7);
break;
case 0x03:
assert((op[off] & 0xc7) == 0x05);
op[off - 1] = 0x81;
op[off] = 0xc0 | ((op[off] >> 3) & 7);
break;
default:
assert(0);
break;
}
}
// 3. insert the new relocs "BEFORE" the original reloc.
pSection.getRelocData()->getRelocationList().insert(
RelocData::iterator(pReloc), reloc);
// 4. change the type of the original reloc
pReloc.setType(llvm::ELF::R_386_TLS_LE);
}
//===--------------------------------------------------------------------===//
// Relocation helper function
//===--------------------------------------------------------------------===//
/// helper_DynRel - Get an relocation entry in .rel.dyn
static
Relocation& helper_DynRel(ResolveInfo* pSym,
Fragment& pFrag,
uint64_t pOffset,
X86Relocator::Type pType,
X86_32Relocator& pParent)
{
X86_32GNULDBackend& ld_backend = pParent.getTarget();
Relocation& rel_entry = *ld_backend.getRelDyn().consumeEntry();
rel_entry.setType(pType);
rel_entry.targetRef().assign(pFrag, pOffset);
if (pType == llvm::ELF::R_386_RELATIVE || NULL == pSym)
rel_entry.setSymInfo(0);
else
rel_entry.setSymInfo(pSym);
return rel_entry;
}
/// helper_use_relative_reloc - Check if symbol can use relocation
/// R_386_RELATIVE
static bool
helper_use_relative_reloc(const ResolveInfo& pSym,
const X86_32Relocator& pFactory)
{
// if symbol is dynamic or undefine or preemptible
if (pSym.isDyn() ||
pSym.isUndef() ||
pFactory.getTarget().isSymbolPreemptible(pSym))
return false;
return true;
}
static
X86_32GOTEntry& helper_get_GOT_and_init(Relocation& pReloc,
X86_32Relocator& pParent)
{
// rsym - The relocation target symbol
ResolveInfo* rsym = pReloc.symInfo();
X86_32GNULDBackend& ld_backend = pParent.getTarget();
X86_32GOTEntry* got_entry = pParent.getSymGOTMap().lookUp(*rsym);
if (NULL != got_entry)
return *got_entry;
// not found
got_entry = ld_backend.getGOT().consume();
pParent.getSymGOTMap().record(*rsym, *got_entry);
// If we first get this GOT entry, we should initialize it.
if (rsym->reserved() & X86Relocator::ReserveGOT) {
// No corresponding dynamic relocation, initialize to the symbol value.
got_entry->setValue(pReloc.symValue());
}
else if (rsym->reserved() & X86Relocator::GOTRel) {
// Initialize got_entry content and the corresponding dynamic relocation.
if (helper_use_relative_reloc(*rsym, pParent)) {
helper_DynRel(rsym, *got_entry, 0x0, llvm::ELF::R_386_RELATIVE, pParent);
got_entry->setValue(pReloc.symValue());
}
else {
helper_DynRel(rsym, *got_entry, 0x0, llvm::ELF::R_386_GLOB_DAT, pParent);
got_entry->setValue(0);
}
}
else {
fatal(diag::reserve_entry_number_mismatch_got);
}
return *got_entry;
}
static
X86Relocator::Address helper_GOT_ORG(X86_32Relocator& pParent)
{
return pParent.getTarget().getGOTPLT().addr();
}
static
X86Relocator::Address helper_GOT(Relocation& pReloc, X86_32Relocator& pParent)
{
X86_32GOTEntry& got_entry = helper_get_GOT_and_init(pReloc, pParent);
X86Relocator::Address got_addr = pParent.getTarget().getGOT().addr();
return got_addr + got_entry.getOffset();
}
static
PLTEntryBase& helper_get_PLT_and_init(Relocation& pReloc,
X86_32Relocator& pParent)
{
// rsym - The relocation target symbol
ResolveInfo* rsym = pReloc.symInfo();
X86_32GNULDBackend& ld_backend = pParent.getTarget();
PLTEntryBase* plt_entry = pParent.getSymPLTMap().lookUp(*rsym);
if (NULL != plt_entry)
return *plt_entry;
// not found
plt_entry = ld_backend.getPLT().consume();
pParent.getSymPLTMap().record(*rsym, *plt_entry);
// If we first get this PLT entry, we should initialize it.
if (rsym->reserved() & X86Relocator::ReservePLT) {
X86_32GOTEntry* gotplt_entry = pParent.getSymGOTPLTMap().lookUp(*rsym);
assert(NULL == gotplt_entry && "PLT entry not exist, but DynRel entry exist!");
gotplt_entry = ld_backend.getGOTPLT().consume();
pParent.getSymGOTPLTMap().record(*rsym, *gotplt_entry);
// init the corresponding rel entry in .rel.plt
Relocation& rel_entry = *ld_backend.getRelPLT().consumeEntry();
rel_entry.setType(llvm::ELF::R_386_JUMP_SLOT);
rel_entry.targetRef().assign(*gotplt_entry);
rel_entry.setSymInfo(rsym);
}
else {
fatal(diag::reserve_entry_number_mismatch_plt);
}
return *plt_entry;
}
static
X86Relocator::Address helper_PLT_ORG(X86_32Relocator& pParent)
{
return pParent.getTarget().getPLT().addr();
}
static
X86Relocator::Address helper_PLT(Relocation& pReloc, X86_32Relocator& pParent)
{
PLTEntryBase& plt_entry = helper_get_PLT_and_init(pReloc, pParent);
return helper_PLT_ORG(pParent) + plt_entry.getOffset();
}
//=========================================//
// Each relocation function implementation //
//=========================================//
// R_386_NONE
X86Relocator::Result none(Relocation& pReloc, X86_32Relocator& pParent)
{
return X86Relocator::OK;
}
// R_386_32: S + A
// R_386_16
// R_386_8
X86Relocator::Result abs(Relocation& pReloc, X86_32Relocator& pParent)
{
ResolveInfo* rsym = pReloc.symInfo();
Relocator::DWord A = pReloc.target() + pReloc.addend();
Relocator::DWord S = pReloc.symValue();
bool has_dyn_rel = pParent.getTarget().symbolNeedsDynRel(
*rsym,
(rsym->reserved() & X86Relocator::ReservePLT),
true);
FragmentRef &target_fragref = pReloc.targetRef();
Fragment *target_frag = target_fragref.frag();
LDSection& target_sect = target_frag->getParent()->getSection();
// If the flag of target section is not ALLOC, we will not scan this relocation
// but perform static relocation. (e.g., applying .debug section)
if (0x0 == (llvm::ELF::SHF_ALLOC & target_sect.flag())) {
pReloc.target() = S + A;
return X86Relocator::OK;
}
// A local symbol may need REL Type dynamic relocation
if (rsym->isLocal() && has_dyn_rel) {
X86Relocator::Type pType = pReloc.type();
if (llvm::ELF::R_386_32 == pType)
pType = llvm::ELF::R_386_RELATIVE;
helper_DynRel(rsym, *target_frag, target_fragref.offset(), pType, pParent);
pReloc.target() = S + A;
return X86Relocator::OK;
}
// An external symbol may need PLT and dynamic relocation
if (!rsym->isLocal()) {
if (rsym->reserved() & X86Relocator::ReservePLT) {
S = helper_PLT(pReloc, pParent);
}
// If we generate a dynamic relocation (except R_386_RELATIVE)
// for a place, we should not perform static relocation on it
// in order to keep the addend store in the place correct.
if (has_dyn_rel) {
if (llvm::ELF::R_386_32 == pReloc.type() &&
helper_use_relative_reloc(*rsym, pParent)) {
helper_DynRel(rsym, *target_frag, target_fragref.offset(),
llvm::ELF::R_386_RELATIVE, pParent);
}
else {
helper_DynRel(rsym, *target_frag, target_fragref.offset(),
pReloc.type(), pParent);
return X86Relocator::OK;
}
}
}
// perform static relocation
pReloc.target() = S + A;
return X86Relocator::OK;
}
// R_386_PC32: S + A - P
// R_386_PC16
// R_386_PC8
X86Relocator::Result rel(Relocation& pReloc, X86_32Relocator& pParent)
{
ResolveInfo* rsym = pReloc.symInfo();
Relocator::DWord A = pReloc.target() + pReloc.addend();
Relocator::DWord S = pReloc.symValue();
Relocator::DWord P = pReloc.place();
LDSection& target_sect = pReloc.targetRef().frag()->getParent()->getSection();
// If the flag of target section is not ALLOC, we will not scan this relocation
// but perform static relocation. (e.g., applying .debug section)
if (0x0 == (llvm::ELF::SHF_ALLOC & target_sect.flag())) {
pReloc.target() = S + A - P;
return X86Relocator::OK;
}
// An external symbol may need PLT and dynamic relocation
if (!rsym->isLocal()) {
if (rsym->reserved() & X86Relocator::ReservePLT) {
S = helper_PLT(pReloc, pParent);
pReloc.target() = S + A - P;
}
if (pParent.getTarget().symbolNeedsDynRel(
*rsym,
(rsym->reserved() & X86Relocator::ReservePLT),
false)) {
if (helper_use_relative_reloc(*rsym, pParent) ) {
helper_DynRel(rsym, *pReloc.targetRef().frag(),
pReloc.targetRef().offset(), llvm::ELF::R_386_RELATIVE, pParent);
}
else {
helper_DynRel(rsym, *pReloc.targetRef().frag(),
pReloc.targetRef().offset(), pReloc.type(), pParent);
return X86Relocator::OK;
}
}
}
// perform static relocation
pReloc.target() = S + A - P;
return X86Relocator::OK;
}
// R_386_GOTOFF: S + A - GOT_ORG
X86Relocator::Result gotoff32(Relocation& pReloc, X86_32Relocator& pParent)
{
Relocator::DWord A = pReloc.target() + pReloc.addend();
X86Relocator::Address GOT_ORG = helper_GOT_ORG(pParent);
X86Relocator::Address S = pReloc.symValue();
pReloc.target() = S + A - GOT_ORG;
return X86Relocator::OK;
}
// R_386_GOTPC: GOT_ORG + A - P
X86Relocator::Result gotpc32(Relocation& pReloc, X86_32Relocator& pParent)
{
Relocator::DWord A = pReloc.target() + pReloc.addend();
X86Relocator::Address GOT_ORG = helper_GOT_ORG(pParent);
// Apply relocation.
pReloc.target() = GOT_ORG + A - pReloc.place();
return X86Relocator::OK;
}
// R_386_GOT32: GOT(S) + A - GOT_ORG
X86Relocator::Result got32(Relocation& pReloc, X86_32Relocator& pParent)
{
if (!(pReloc.symInfo()->reserved()
& (X86Relocator::ReserveGOT | X86Relocator::GOTRel))) {
return X86Relocator::BadReloc;
}
X86Relocator::Address GOT_S = helper_GOT(pReloc, pParent);
Relocator::DWord A = pReloc.target() + pReloc.addend();
X86Relocator::Address GOT_ORG = helper_GOT_ORG(pParent);
// Apply relocation.
pReloc.target() = GOT_S + A - GOT_ORG;
return X86Relocator::OK;
}
// R_386_PLT32: PLT(S) + A - P
X86Relocator::Result plt32(Relocation& pReloc, X86_32Relocator& pParent)
{
// PLT_S depends on if there is a PLT entry.
X86Relocator::Address PLT_S;
if ((pReloc.symInfo()->reserved() & X86Relocator::ReservePLT))
PLT_S = helper_PLT(pReloc, pParent);
else
PLT_S = pReloc.symValue();
Relocator::DWord A = pReloc.target() + pReloc.addend();
X86Relocator::Address P = pReloc.place();
pReloc.target() = PLT_S + A - P;
return X86Relocator::OK;
}
// R_386_TLS_GD:
X86Relocator::Result tls_gd(Relocation& pReloc, X86_32Relocator& pParent)
{
// global-dynamic
ResolveInfo* rsym = pReloc.symInfo();
// must reserve two pairs of got and dynamic relocation
if (!(rsym->reserved() & X86Relocator::GOTRel)) {
return X86Relocator::BadReloc;
}
X86_32GNULDBackend& ld_backend = pParent.getTarget();
ELFFileFormat* file_format = pParent.getTarget().getOutputFormat();
// setup corresponding got and dynamic relocatio entries:
// get first got entry, if there is already a got entry for rsym, then apply
// this relocation to the got entry directly. If not, setup the corresponding
// got and dyn relocation entries
X86_32GOTEntry* got_entry1 = pParent.getSymGOTMap().lookUp(*rsym);
if (NULL == got_entry1) {
// get and init two got entries if not exist
got_entry1 = ld_backend.getGOT().consume();
pParent.getSymGOTMap().record(*rsym, *got_entry1);
X86_32GOTEntry* got_entry2 = ld_backend.getGOT().consume();
got_entry1->setValue(0x0);
got_entry2->setValue(0x0);
// setup dyn rel for get_entry1
Relocation& rel_entry1 = helper_DynRel(rsym, *got_entry1, 0x0,
llvm::ELF::R_386_TLS_DTPMOD32, pParent);
if (rsym->isLocal()) {
// for local symbol, set got_entry2 to symbol value
got_entry2->setValue(pReloc.symValue());
// for local tls symbol, add rel entry against the section symbol this
// symbol belong to (.tdata or .tbss)
const LDSection* sym_sect =
&rsym->outSymbol()->fragRef()->frag()->getParent()->getSection();
ResolveInfo* sect_sym = NULL;
if (&file_format->getTData() == sym_sect)
sect_sym = pParent.getTarget().getTDATASymbol().resolveInfo();
else
sect_sym = pParent.getTarget().getTBSSSymbol().resolveInfo();
rel_entry1.setSymInfo(sect_sym);
}
else {
// for non-local symbol, add a pair of rel entries against this symbol
// for those two got entries
helper_DynRel(rsym, *got_entry2, 0x0,
llvm::ELF::R_386_TLS_DTPOFF32, pParent);
}
}
// perform relocation to the first got entry
Relocator::DWord A = pReloc.target() + pReloc.addend();
// GOT_OFF - the offset between the got_entry1 and _GLOBAL_OFFSET_TABLE (the
// .got.plt section)
X86Relocator::Address GOT_OFF =
file_format->getGOT().addr() +
got_entry1->getOffset() -
file_format->getGOTPLT().addr();
pReloc.target() = GOT_OFF + A;
return X86Relocator::OK;
}
// R_386_TLS_LDM
X86Relocator::Result tls_ldm(Relocation& pReloc, X86_32Relocator& pParent)
{
// FIXME: no linker optimization for TLS relocation
const X86_32GOTEntry& got_entry = pParent.getTLSModuleID();
// All GOT offsets are relative to the end of the GOT.
X86Relocator::SWord GOT_S = got_entry.getOffset() -
(pParent.getTarget().getGOTPLT().addr() -
pParent.getTarget().getGOT().addr());
Relocator::DWord A = pReloc.target() + pReloc.addend();
pReloc.target() = GOT_S + A;
return X86Relocator::OK;
}
// R_386_TLS_LDO_32
X86Relocator::Result tls_ldo_32(Relocation& pReloc, X86_32Relocator& pParent)
{
// FIXME: no linker optimization for TLS relocation
Relocator::DWord A = pReloc.target() + pReloc.addend();
X86Relocator::Address S = pReloc.symValue();
pReloc.target() = S + A;
return X86Relocator::OK;
}
// R_X86_TLS_IE
X86Relocator::Result tls_ie(Relocation& pReloc, X86_32Relocator& pParent)
{
ResolveInfo* rsym = pReloc.symInfo();
if (!(rsym->reserved() & X86Relocator::GOTRel)) {
return X86Relocator::BadReloc;
}
if (rsym->reserved() & X86Relocator::ReserveRel) {
// when building shared object, set up a RELATIVE dynamic relocation
helper_DynRel(rsym, *pReloc.targetRef().frag(), pReloc.targetRef().offset(),
llvm::ELF::R_386_RELATIVE, pParent);
}
// set up the got and dynamic relocation entries if not exist
X86_32GOTEntry* got_entry = pParent.getSymGOTMap().lookUp(*rsym);
if (NULL == got_entry) {
// set got entry
X86_32GNULDBackend& ld_backend = pParent.getTarget();
got_entry = ld_backend.getGOT().consume();
pParent.getSymGOTMap().record(*rsym, *got_entry);
got_entry->setValue(0x0);
// set relocation entry
Relocation& rel_entry = *ld_backend.getRelDyn().consumeEntry();
rel_entry.setType(llvm::ELF::R_386_TLS_TPOFF);
rel_entry.setSymInfo(rsym);
rel_entry.targetRef().assign(*got_entry);
}
// perform relocation to the absolute address of got_entry
X86Relocator::Address GOT_S =
pParent.getTarget().getGOT().addr() + got_entry->getOffset();
Relocator::DWord A = pReloc.target() + pReloc.addend();
pReloc.target() = GOT_S + A;
return X86Relocator::OK;
}
// R_386_TLS_GOTIE
X86Relocator::Result tls_gotie(Relocation& pReloc, X86_32Relocator& pParent)
{
ResolveInfo* rsym = pReloc.symInfo();
if (!(rsym->reserved() & X86Relocator::GOTRel)) {
return X86Relocator::BadReloc;
}
// set up the got and dynamic relocation entries if not exist
X86_32GOTEntry* got_entry = pParent.getSymGOTMap().lookUp(*rsym);
if (NULL == got_entry) {
// set got entry
X86_32GNULDBackend& ld_backend = pParent.getTarget();
got_entry = ld_backend.getGOT().consume();
pParent.getSymGOTMap().record(*rsym, *got_entry);
got_entry->setValue(0x0);
// set relocation entry
Relocation& rel_entry = *ld_backend.getRelDyn().consumeEntry();
rel_entry.setType(llvm::ELF::R_386_TLS_TPOFF);
rel_entry.setSymInfo(rsym);
rel_entry.targetRef().assign(*got_entry);
}
// All GOT offsets are relative to the end of the GOT.
X86Relocator::SWord GOT_S = got_entry->getOffset() -
(pParent.getTarget().getGOTPLT().addr() - pParent.getTarget().getGOT().addr());
Relocator::DWord A = pReloc.target() + pReloc.addend();
pReloc.target() = GOT_S + A;
return X86Relocator::OK;
}
// R_X86_TLS_LE
X86Relocator::Result tls_le(Relocation& pReloc, X86_32Relocator& pParent)
{
ResolveInfo* rsym = pReloc.symInfo();
if (pReloc.symInfo()->reserved() & X86Relocator::ReserveRel) {
helper_DynRel(rsym,
*pReloc.targetRef().frag(),
pReloc.targetRef().offset(),
llvm::ELF::R_386_TLS_TPOFF,
pParent);
return X86Relocator::OK;
}
// perform static relocation
// get TLS segment
ELFSegment* tls_seg = pParent.getTarget().elfSegmentTable().find(
llvm::ELF::PT_TLS, llvm::ELF::PF_R, 0x0);
Relocator::DWord A = pReloc.target() + pReloc.addend();
X86Relocator::Address S = pReloc.symValue();
pReloc.target() = S + A - tls_seg->memsz();
return X86Relocator::OK;
}
X86Relocator::Result unsupport(Relocation& pReloc, X86_32Relocator& pParent)
{
return X86Relocator::Unsupport;
}
//===--------------------------------------------------------------------===//
// Relocation Functions and Tables
//===--------------------------------------------------------------------===//
DECL_X86_64_APPLY_RELOC_FUNCS
/// the prototype of applying function
typedef Relocator::Result (*X86_64ApplyFunctionType)(Relocation& pReloc,
X86_64Relocator& pParent);
// the table entry of applying functions
struct X86_64ApplyFunctionTriple
{
X86_64ApplyFunctionType func;
unsigned int type;
const char* name;
unsigned int size;
};
// declare the table of applying functions
static const X86_64ApplyFunctionTriple X86_64ApplyFunctions[] = {
DECL_X86_64_APPLY_RELOC_FUNC_PTRS
};
//===--------------------------------------------------------------------===//
// X86_64Relocator
//===--------------------------------------------------------------------===//
X86_64Relocator::X86_64Relocator(X86_64GNULDBackend& pParent,
const LinkerConfig& pConfig)
: X86Relocator(pConfig), m_Target(pParent) {
}
Relocator::Result
X86_64Relocator::applyRelocation(Relocation& pRelocation)
{
Relocation::Type type = pRelocation.type();
if (type >= sizeof (X86_64ApplyFunctions) / sizeof (X86_64ApplyFunctions[0]) ) {
return Unknown;
}
// apply the relocation
return X86_64ApplyFunctions[type].func(pRelocation, *this);
}
const char* X86_64Relocator::getName(Relocation::Type pType) const
{
return X86_64ApplyFunctions[pType].name;
}
Relocator::Size X86_64Relocator::getSize(Relocation::Type pType) const
{
return X86_64ApplyFunctions[pType].size;
}
void X86_64Relocator::scanLocalReloc(Relocation& pReloc,
IRBuilder& pBuilder,
Module& pModule,
LDSection& pSection)
{
// rsym - The relocation target symbol
ResolveInfo* rsym = pReloc.symInfo();
switch(pReloc.type()){
case llvm::ELF::R_X86_64_64:
case llvm::ELF::R_X86_64_32:
case llvm::ELF::R_X86_64_16:
case llvm::ELF::R_X86_64_8:
case llvm::ELF::R_X86_64_32S:
// If buiding PIC object (shared library or PIC executable),
// a dynamic relocations with RELATIVE type to this location is needed.
// Reserve an entry in .rela.dyn
if (config().isCodeIndep()) {
getTarget().getRelDyn().reserveEntry();
// set Rel bit
rsym->setReserved(rsym->reserved() | ReserveRel);
getTarget().checkAndSetHasTextRel(*pSection.getLink());
}
return;
case llvm::ELF::R_X86_64_PC32:
case llvm::ELF::R_X86_64_PC16:
case llvm::ELF::R_X86_64_PC8:
return;
case llvm::ELF::R_X86_64_GOTPCREL:
// Symbol needs GOT entry, reserve entry in .got
// return if we already create GOT for this symbol
if (rsym->reserved() & (ReserveGOT | GOTRel))
return;
getTarget().getGOT().reserve();
// If the GOT is used in statically linked binaries,
// the GOT entry is enough and no relocation is needed.
if (config().isCodeStatic()) {
rsym->setReserved(rsym->reserved() | ReserveGOT);
return;
}
// If building shared object or the symbol is undefined, a dynamic
// relocation is needed to relocate this GOT entry. Reserve an
// entry in .rela.dyn
if (LinkerConfig::DynObj ==
config().codeGenType() || rsym->isUndef() || rsym->isDyn()) {
getTarget().getRelDyn().reserveEntry();
// set GOTRel bit
rsym->setReserved(rsym->reserved() | GOTRel);
return;
}
// set GOT bit
rsym->setReserved(rsym->reserved() | ReserveGOT);
return;
default:
fatal(diag::unsupported_relocation) << (int)pReloc.type()
<< "mclinker@googlegroups.com";
break;
} // end switch
}
void X86_64Relocator::scanGlobalReloc(Relocation& pReloc,
IRBuilder& pBuilder,
Module& pModule,
LDSection& pSection)
{
// rsym - The relocation target symbol
ResolveInfo* rsym = pReloc.symInfo();
switch(pReloc.type()) {
case llvm::ELF::R_X86_64_64:
case llvm::ELF::R_X86_64_32:
case llvm::ELF::R_X86_64_16:
case llvm::ELF::R_X86_64_8:
case llvm::ELF::R_X86_64_32S:
// Absolute relocation type, symbol may needs PLT entry or
// dynamic relocation entry
if (getTarget().symbolNeedsPLT(*rsym)) {
// create plt for this symbol if it does not have one
if (!(rsym->reserved() & ReservePLT)){
// Symbol needs PLT entry, we need to reserve a PLT entry
// and the corresponding GOT and dynamic relocation entry
// in .got and .rela.plt. (GOT entry will be reserved simultaneously
// when calling X86PLT->reserveEntry())
getTarget().getPLT().reserveEntry();
getTarget().getGOTPLT().reserve();
getTarget().getRelPLT().reserveEntry();
// set PLT bit
rsym->setReserved(rsym->reserved() | ReservePLT);
}
}
if (getTarget().symbolNeedsDynRel(*rsym, (rsym->reserved() & ReservePLT), true)) {
// symbol needs dynamic relocation entry, reserve an entry in .rela.dyn
getTarget().getRelDyn().reserveEntry();
if (getTarget().symbolNeedsCopyReloc(pReloc, *rsym)) {
LDSymbol& cpy_sym = defineSymbolforCopyReloc(pBuilder, *rsym, getTarget());
addCopyReloc(*cpy_sym.resolveInfo(), getTarget());
}
else {
// set Rel bit
rsym->setReserved(rsym->reserved() | ReserveRel);
getTarget().checkAndSetHasTextRel(*pSection.getLink());
}
}
return;
case llvm::ELF::R_X86_64_GOTPCREL:
// Symbol needs GOT entry, reserve entry in .got
// return if we already create GOT for this symbol
if (rsym->reserved() & (ReserveGOT | GOTRel))
return;
getTarget().getGOT().reserve();
// If the GOT is used in statically linked binaries,
// the GOT entry is enough and no relocation is needed.
if (config().isCodeStatic()) {
rsym->setReserved(rsym->reserved() | ReserveGOT);
return;
}
// If building shared object or the symbol is undefined, a dynamic
// relocation is needed to relocate this GOT entry. Reserve an
// entry in .rela.dyn
if (LinkerConfig::DynObj ==
config().codeGenType() || rsym->isUndef() || rsym->isDyn()) {
getTarget().getRelDyn().reserveEntry();
// set GOTRel bit
rsym->setReserved(rsym->reserved() | GOTRel);
return;
}
// set GOT bit
rsym->setReserved(rsym->reserved() | ReserveGOT);
return;
case llvm::ELF::R_X86_64_PLT32:
// A PLT entry is needed when building shared library
// return if we already create plt for this symbol
if (rsym->reserved() & ReservePLT)
return;
// if the symbol's value can be decided at link time, then no need plt
if (getTarget().symbolFinalValueIsKnown(*rsym))
return;
// if symbol is defined in the ouput file and it's not
// preemptible, no need plt
if (rsym->isDefine() && !rsym->isDyn() &&
!getTarget().isSymbolPreemptible(*rsym)) {
return;
}
// Symbol needs PLT entry, we need to reserve a PLT entry
// and the corresponding GOT and dynamic relocation entry
// in .got and .rel.plt. (GOT entry will be reserved simultaneously
// when calling X86PLT->reserveEntry())
getTarget().getPLT().reserveEntry();
getTarget().getGOTPLT().reserve();
getTarget().getRelPLT().reserveEntry();
// set PLT bit
rsym->setReserved(rsym->reserved() | ReservePLT);
return;
case llvm::ELF::R_X86_64_PC32:
case llvm::ELF::R_X86_64_PC16:
case llvm::ELF::R_X86_64_PC8:
if (getTarget().symbolNeedsPLT(*rsym) &&
LinkerConfig::DynObj != config().codeGenType()) {
// create plt for this symbol if it does not have one
if (!(rsym->reserved() & ReservePLT)){
// Symbol needs PLT entry, we need to reserve a PLT entry
// and the corresponding GOT and dynamic relocation entry
// in .got and .rel.plt. (GOT entry will be reserved simultaneously
// when calling X86PLT->reserveEntry())
getTarget().getPLT().reserveEntry();
getTarget().getGOTPLT().reserve();
getTarget().getRelPLT().reserveEntry();
// set PLT bit
rsym->setReserved(rsym->reserved() | ReservePLT);
}
}
// Only PC relative relocation against dynamic symbol needs a
// dynamic relocation. Only dynamic copy relocation is allowed
// and PC relative relocation will be resolved to the local copy.
// All other dynamic relocations may lead to run-time relocation
// overflow.
if (getTarget().isDynamicSymbol(*rsym) &&
getTarget().symbolNeedsDynRel(*rsym, (rsym->reserved() & ReservePLT), false) &&
getTarget().symbolNeedsCopyReloc(pReloc, *rsym)) {
getTarget().getRelDyn().reserveEntry();
LDSymbol& cpy_sym = defineSymbolforCopyReloc(pBuilder, *rsym, getTarget());
addCopyReloc(*cpy_sym.resolveInfo(), getTarget());
}
return;
default:
fatal(diag::unsupported_relocation) << (int)pReloc.type()
<< "mclinker@googlegroups.com";
break;
} // end switch
}
//===--------------------------------------------------------------------===//
// Relocation helper function
//===--------------------------------------------------------------------===//
/// helper_DynRel - Get an relocation entry in .rela.dyn
static
Relocation& helper_DynRel(ResolveInfo* pSym,
Fragment& pFrag,
uint64_t pOffset,
X86Relocator::Type pType,
X86_64Relocator& pParent)
{
X86_64GNULDBackend& ld_backend = pParent.getTarget();
Relocation& rel_entry = *ld_backend.getRelDyn().consumeEntry();
rel_entry.setType(pType);
rel_entry.targetRef().assign(pFrag, pOffset);
if (pType == llvm::ELF::R_X86_64_RELATIVE || NULL == pSym)
rel_entry.setSymInfo(0);
else
rel_entry.setSymInfo(pSym);
return rel_entry;
}
/// helper_use_relative_reloc - Check if symbol can use relocation
/// R_X86_64_RELATIVE
static bool
helper_use_relative_reloc(const ResolveInfo& pSym,
const X86_64Relocator& pFactory)
{
// if symbol is dynamic or undefine or preemptible
if (pSym.isDyn() ||
pSym.isUndef() ||
pFactory.getTarget().isSymbolPreemptible(pSym))
return false;
return true;
}
static
X86_64GOTEntry& helper_get_GOT_and_init(Relocation& pReloc,
X86_64Relocator& pParent)
{
// rsym - The relocation target symbol
ResolveInfo* rsym = pReloc.symInfo();
X86_64GNULDBackend& ld_backend = pParent.getTarget();
X86_64GOTEntry* got_entry = pParent.getSymGOTMap().lookUp(*rsym);
if (NULL != got_entry)
return *got_entry;
// not found
got_entry = ld_backend.getGOT().consume();
pParent.getSymGOTMap().record(*rsym, *got_entry);
// If we first get this GOT entry, we should initialize it.
if (rsym->reserved() & X86Relocator::ReserveGOT) {
// No corresponding dynamic relocation, initialize to the symbol value.
got_entry->setValue(pReloc.symValue());
}
else if (rsym->reserved() & X86Relocator::GOTRel) {
// Initialize got_entry content and the corresponding dynamic relocation.
if (helper_use_relative_reloc(*rsym, pParent)) {
Relocation& rel_entry = helper_DynRel(rsym, *got_entry, 0x0,
llvm::ELF::R_X86_64_RELATIVE,
pParent);
rel_entry.setAddend(pReloc.symValue());
}
else {
helper_DynRel(rsym, *got_entry, 0x0, llvm::ELF::R_X86_64_GLOB_DAT,
pParent);
}
got_entry->setValue(0);
}
else {
fatal(diag::reserve_entry_number_mismatch_got);
}
return *got_entry;
}
static
X86Relocator::Address helper_GOT_ORG(X86_64Relocator& pParent)
{
return pParent.getTarget().getGOT().addr();
}
static
X86Relocator::Address helper_GOT(Relocation& pReloc, X86_64Relocator& pParent)
{
X86_64GOTEntry& got_entry = helper_get_GOT_and_init(pReloc, pParent);
return got_entry.getOffset();
}
static
PLTEntryBase& helper_get_PLT_and_init(Relocation& pReloc,
X86_64Relocator& pParent)
{
// rsym - The relocation target symbol
ResolveInfo* rsym = pReloc.symInfo();
X86_64GNULDBackend& ld_backend = pParent.getTarget();
PLTEntryBase* plt_entry = pParent.getSymPLTMap().lookUp(*rsym);
if (NULL != plt_entry)
return *plt_entry;
// not found
plt_entry = ld_backend.getPLT().consume();
pParent.getSymPLTMap().record(*rsym, *plt_entry);
// If we first get this PLT entry, we should initialize it.
if (rsym->reserved() & X86Relocator::ReservePLT) {
X86_64GOTEntry* gotplt_entry = pParent.getSymGOTPLTMap().lookUp(*rsym);
assert(NULL == gotplt_entry && "PLT entry not exist, but DynRel entry exist!");
gotplt_entry = ld_backend.getGOTPLT().consume();
pParent.getSymGOTPLTMap().record(*rsym, *gotplt_entry);
// init the corresponding rel entry in .rel.plt
Relocation& rel_entry = *ld_backend.getRelPLT().consumeEntry();
rel_entry.setType(llvm::ELF::R_X86_64_JUMP_SLOT);
rel_entry.targetRef().assign(*gotplt_entry);
rel_entry.setSymInfo(rsym);
}
else {
fatal(diag::reserve_entry_number_mismatch_plt);
}
return *plt_entry;
}
static
X86Relocator::Address helper_PLT_ORG(X86_64Relocator& pParent)
{
return pParent.getTarget().getPLT().addr();
}
static
X86Relocator::Address helper_PLT(Relocation& pReloc, X86_64Relocator& pParent)
{
PLTEntryBase& plt_entry = helper_get_PLT_and_init(pReloc, pParent);
return helper_PLT_ORG(pParent) + plt_entry.getOffset();
}
//
// R_X86_64_NONE
X86Relocator::Result none(Relocation& pReloc, X86_64Relocator& pParent)
{
return X86Relocator::OK;
}
// R_X86_64_64: S + A
// R_X86_64_32:
// R_X86_64_16:
// R_X86_64_8
X86Relocator::Result abs(Relocation& pReloc, X86_64Relocator& pParent)
{
ResolveInfo* rsym = pReloc.symInfo();
Relocator::DWord A = pReloc.target() + pReloc.addend();
Relocator::DWord S = pReloc.symValue();
bool has_dyn_rel = pParent.getTarget().symbolNeedsDynRel(
*rsym,
(rsym->reserved() & X86Relocator::ReservePLT),
true);
FragmentRef &target_fragref = pReloc.targetRef();
Fragment *target_frag = target_fragref.frag();
LDSection& target_sect = target_frag->getParent()->getSection();
// If the flag of target section is not ALLOC, we will not scan this relocation
// but perform static relocation. (e.g., applying .debug section)
if (0x0 == (llvm::ELF::SHF_ALLOC & target_sect.flag())) {
pReloc.target() = S + A;
return X86Relocator::OK;
}
// A local symbol may need RELA Type dynamic relocation
if (rsym->isLocal() && has_dyn_rel) {
X86Relocator::Type pType = pReloc.type();
if (llvm::ELF::R_X86_64_64 == pType)
pType = llvm::ELF::R_X86_64_RELATIVE;
Relocation& rel_entry = helper_DynRel(rsym, *target_frag,
target_fragref.offset(), pType, pParent);
rel_entry.setAddend(S + A);
return X86Relocator::OK;
}
// An external symbol may need PLT and dynamic relocation
if (!rsym->isLocal()) {
if (rsym->reserved() & X86Relocator::ReservePLT) {
S = helper_PLT(pReloc, pParent);
}
// If we generate a dynamic relocation (except R_X86_64_RELATIVE)
// for a place, we should not perform static relocation on it
// in order to keep the addend store in the place correct.
if (has_dyn_rel) {
if (llvm::ELF::R_X86_64_64 == pReloc.type() &&
helper_use_relative_reloc(*rsym, pParent)) {
Relocation& rel_entry = helper_DynRel(rsym, *target_frag,
target_fragref.offset(), llvm::ELF::R_X86_64_RELATIVE, pParent);
rel_entry.setAddend(S + A);
}
else {
Relocation& rel_entry = helper_DynRel(rsym, *target_frag,
target_fragref.offset(), pReloc.type(), pParent);
rel_entry.setAddend(A);
return X86Relocator::OK;
}
}
}
// perform static relocation
pReloc.target() = S + A;
return X86Relocator::OK;
}
// R_X86_64_32S: S + A
X86Relocator::Result signed32(Relocation& pReloc, X86_64Relocator& pParent)
{
ResolveInfo* rsym = pReloc.symInfo();
Relocator::DWord A = pReloc.target() + pReloc.addend();
Relocator::DWord S = pReloc.symValue();
bool has_dyn_rel = pParent.getTarget().symbolNeedsDynRel(
*rsym,
(rsym->reserved() & X86Relocator::ReservePLT),
true);
// There should be no dynamic relocations for R_X86_64_32S.
if (has_dyn_rel)
return X86Relocator::BadReloc;
LDSection& target_sect = pReloc.targetRef().frag()->getParent()->getSection();
// If the flag of target section is not ALLOC, we will not scan this relocation
// but perform static relocation. (e.g., applying .debug section)
// An external symbol may need PLT and dynamic relocation
if (0x0 != (llvm::ELF::SHF_ALLOC & target_sect.flag()) &&
!rsym->isLocal() && rsym->reserved() & X86Relocator::ReservePLT)
S = helper_PLT(pReloc, pParent);
#if notyet
// Check 32-bit signed overflow.
Relocator::SWord V = S + A;
if (V > INT64_C(0x7fffffff) || V < INT64_C(-0x80000000))
return X86Relocator::Overflow;
#endif
// perform static relocation
pReloc.target() = S + A;
return X86Relocator::OK;
}
// R_X86_64_GOTPCREL: GOT(S) + GOT_ORG + A - P
X86Relocator::Result gotpcrel(Relocation& pReloc, X86_64Relocator& pParent)
{
if (!(pReloc.symInfo()->reserved()
& (X86Relocator::ReserveGOT | X86Relocator::GOTRel))) {
return X86Relocator::BadReloc;
}
X86Relocator::Address GOT_S = helper_GOT(pReloc, pParent);
Relocator::DWord A = pReloc.target() + pReloc.addend();
X86Relocator::Address GOT_ORG = helper_GOT_ORG(pParent);
// Apply relocation.
pReloc.target() = GOT_S + GOT_ORG + A - pReloc.place();
return X86Relocator::OK;
}
// R_X86_64_PLT32: PLT(S) + A - P
X86Relocator::Result plt32(Relocation& pReloc, X86_64Relocator& pParent)
{
// PLT_S depends on if there is a PLT entry.
X86Relocator::Address PLT_S;
if ((pReloc.symInfo()->reserved() & X86Relocator::ReservePLT))
PLT_S = helper_PLT(pReloc, pParent);
else
PLT_S = pReloc.symValue();
Relocator::DWord A = pReloc.target() + pReloc.addend();
X86Relocator::Address P = pReloc.place();
pReloc.target() = PLT_S + A - P;
return X86Relocator::OK;
}
// R_X86_64_PC32: S + A - P
// R_X86_64_PC16
// R_X86_64_PC8
X86Relocator::Result rel(Relocation& pReloc, X86_64Relocator& pParent)
{
ResolveInfo* rsym = pReloc.symInfo();
Relocator::DWord A = pReloc.target() + pReloc.addend();
Relocator::DWord S = pReloc.symValue();
Relocator::DWord P = pReloc.place();
LDSection& target_sect = pReloc.targetRef().frag()->getParent()->getSection();
// If the flag of target section is not ALLOC, we will not scan this relocation
// but perform static relocation. (e.g., applying .debug section)
if (0x0 == (llvm::ELF::SHF_ALLOC & target_sect.flag())) {
pReloc.target() = S + A - P;
return X86Relocator::OK;
}
// An external symbol may need PLT and dynamic relocation
if (!rsym->isLocal()) {
if (rsym->reserved() & X86Relocator::ReservePLT) {
S = helper_PLT(pReloc, pParent);
pReloc.target() = S + A - P;
}
if (pParent.getTarget().symbolNeedsDynRel(
*rsym,
(rsym->reserved() & X86Relocator::ReservePLT),
false)) {
return X86Relocator::Overflow;
}
}
// perform static relocation
pReloc.target() = S + A - P;
return X86Relocator::OK;
}
X86Relocator::Result unsupport(Relocation& pReloc, X86_64Relocator& pParent)
{
return X86Relocator::Unsupport;
}