Files
clang-p2996/lld/lib/ReaderWriter/ELF/AArch64/AArch64RelocationPass.cpp
Hans Wennborg d2228c0f72 AArch64: replace __func__ with LLVM_FUNCTION_NAME
MSVC doesn't define __func__.

llvm-svn: 215578
2014-08-13 21:08:39 +00:00

536 lines
17 KiB
C++

//===- lib/ReaderWriter/ELF/AArch64/AArch64RelocationPass.cpp -------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// \brief Defines the relocation processing pass for AArch64. This includes
/// GOT and PLT entries, TLS, COPY, and ifunc.
///
/// This also includes additional behavior that gnu-ld and gold implement but
/// which is not specified anywhere.
///
//===----------------------------------------------------------------------===//
#include "AArch64RelocationPass.h"
#include "lld/Core/Simple.h"
#include "llvm/ADT/DenseMap.h"
#include "Atoms.h"
#include "AArch64LinkingContext.h"
#include "llvm/Support/Debug.h"
using namespace lld;
using namespace lld::elf;
using namespace llvm::ELF;
namespace {
// .got values
const uint8_t AArch64GotAtomContent[8] = {0};
// .plt value (entry 0)
const uint8_t AArch64Plt0AtomContent[32] = {
0xf0, 0x7b, 0xbf,
0xa9, // stp x16, x30, [sp,#-16]!
0x10, 0x00, 0x00,
0x90, // adrp x16, Page(eh_frame)
0x11, 0x02, 0x40,
0xf9, // ldr x17, [x16,#offset]
0x10, 0x02, 0x00,
0x91, // add x16, x16, #offset
0x20, 0x02, 0x1f,
0xd6, // br x17
0x1f, 0x20, 0x03,
0xd5, // nop
0x1f, 0x20, 0x03,
0xd5, // nop
0x1f, 0x20, 0x03,
0xd5 // nop
};
// .plt values (other entries)
const uint8_t AArch64PltAtomContent[16] = {
0x10, 0x00, 0x00,
0x90, // adrp x16, PAGE(<GLOBAL_OFFSET_TABLE>)
0x11, 0x02, 0x40,
0xf9, // ldr x17, [x16,#offset]
0x10, 0x02, 0x00,
0x91, // add x16, x16, #offset
0x20, 0x02, 0x1f,
0xd6 // br x17
};
/// \brief Atoms that are used by AArch64 dynamic linking
class AArch64GOTAtom : public GOTAtom {
public:
AArch64GOTAtom(const File &f, StringRef secName) : GOTAtom(f, secName) {}
ArrayRef<uint8_t> rawContent() const override {
return ArrayRef<uint8_t>(AArch64GotAtomContent, 8);
}
};
class AArch64PLT0Atom : public PLT0Atom {
public:
AArch64PLT0Atom(const File &f) : PLT0Atom(f) {
#ifndef NDEBUG
_name = ".PLT0";
#endif
}
ArrayRef<uint8_t> rawContent() const override {
return ArrayRef<uint8_t>(AArch64Plt0AtomContent, 32);
}
};
class AArch64PLTAtom : public PLTAtom {
public:
AArch64PLTAtom(const File &f, StringRef secName) : PLTAtom(f, secName) {}
ArrayRef<uint8_t> rawContent() const override {
return ArrayRef<uint8_t>(AArch64PltAtomContent, 16);
}
};
class ELFPassFile : public SimpleFile {
public:
ELFPassFile(const ELFLinkingContext &eti) : SimpleFile("ELFPassFile") {
setOrdinal(eti.getNextOrdinalAndIncrement());
}
llvm::BumpPtrAllocator _alloc;
};
/// \brief CRTP base for handling relocations.
template <class Derived> class AArch64RelocationPass : public Pass {
/// \brief Handle a specific reference.
void handleReference(const DefinedAtom &atom, const Reference &ref) {
DEBUG_WITH_TYPE(
"AArch64", llvm::dbgs()
<< "\t" << LLVM_FUNCTION_NAME << "()"
<< ": Name of Defined Atom: " << atom.name().str();
llvm::dbgs() << " kindValue: " << ref.kindValue() << "\n");
if (ref.kindNamespace() != Reference::KindNamespace::ELF)
return;
assert(ref.kindArch() == Reference::KindArch::AArch64);
switch (ref.kindValue()) {
case R_AARCH64_ABS32:
case R_AARCH64_ABS16:
case R_AARCH64_ABS64:
case R_AARCH64_PREL16:
case R_AARCH64_PREL32:
case R_AARCH64_PREL64:
static_cast<Derived *>(this)->handlePlain(ref);
break;
case R_AARCH64_GOTREL32:
case R_AARCH64_GOTREL64:
static_cast<Derived *>(this)->handleGOT(ref);
break;
case R_AARCH64_ADR_PREL_PG_HI21:
static_cast<Derived *>(this)->handlePlain(ref);
break;
case R_AARCH64_LDST8_ABS_LO12_NC:
case R_AARCH64_LDST16_ABS_LO12_NC:
case R_AARCH64_LDST32_ABS_LO12_NC:
case R_AARCH64_LDST64_ABS_LO12_NC:
case R_AARCH64_LDST128_ABS_LO12_NC:
static_cast<Derived *>(this)->handlePlain(ref);
break;
case R_AARCH64_ADD_ABS_LO12_NC:
static_cast<Derived *>(this)->handlePlain(ref);
break;
case R_AARCH64_CALL26:
case R_AARCH64_JUMP26:
case R_AARCH64_CONDBR19:
static_cast<Derived *>(this)->handlePlain(ref);
break;
case R_AARCH64_TLSLE_ADD_TPREL_HI12:
case R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
static_cast<Derived *>(this)->handlePlain(ref);
break;
case R_AARCH64_ADR_GOT_PAGE:
case R_AARCH64_LD64_GOT_LO12_NC:
case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
static_cast<Derived *>(this)->handleGOT(ref);
break;
default:
llvm_unreachable("Unhandled type in handleReference");
}
}
protected:
/// \brief get the PLT entry for a given IFUNC Atom.
///
/// If the entry does not exist. Both the GOT and PLT entry is created.
const PLTAtom *getIFUNCPLTEntry(const DefinedAtom *da) {
auto plt = _pltMap.find(da);
if (plt != _pltMap.end())
return plt->second;
auto ga = new (_file._alloc) AArch64GOTAtom(_file, ".got.plt");
ga->addReferenceELF_AArch64(R_AARCH64_IRELATIVE, 0, da, 0);
auto pa = new (_file._alloc) AArch64PLTAtom(_file, ".plt");
pa->addReferenceELF_AArch64(R_AARCH64_PREL32, 2, ga, -4);
#ifndef NDEBUG
ga->_name = "__got_ifunc_";
ga->_name += da->name();
pa->_name = "__plt_ifunc_";
pa->_name += da->name();
#endif
_gotMap[da] = ga;
_pltMap[da] = pa;
_gotVector.push_back(ga);
_pltVector.push_back(pa);
return pa;
}
/// \brief Redirect the call to the PLT stub for the target IFUNC.
///
/// This create a PLT and GOT entry for the IFUNC if one does not exist. The
/// GOT entry and a IRELATIVE relocation to the original target resolver.
std::error_code handleIFUNC(const Reference &ref) {
auto target = dyn_cast_or_null<const DefinedAtom>(ref.target());
if (target && target->contentType() == DefinedAtom::typeResolver)
const_cast<Reference &>(ref).setTarget(getIFUNCPLTEntry(target));
return std::error_code();
}
/// \brief Create a GOT entry for the TP offset of a TLS atom.
const GOTAtom *getGOTTPOFF(const Atom *atom) {
auto got = _gotMap.find(atom);
if (got == _gotMap.end()) {
auto g = new (_file._alloc) AArch64GOTAtom(_file, ".got");
g->addReferenceELF_AArch64(R_AARCH64_GOTREL64, 0, atom, 0);
#ifndef NDEBUG
g->_name = "__got_tls_";
g->_name += atom->name();
#endif
_gotMap[atom] = g;
_gotVector.push_back(g);
return g;
}
return got->second;
}
/// \brief Create a TPOFF64 GOT entry and change the relocation to a PC32 to
/// the GOT.
void handleGOTTPOFF(const Reference &ref) {
const_cast<Reference &>(ref).setTarget(getGOTTPOFF(ref.target()));
const_cast<Reference &>(ref).setKindValue(R_AARCH64_PREL32);
}
/// \brief Create a GOT entry containing 0.
const GOTAtom *getNullGOT() {
if (!_null) {
_null = new (_file._alloc) AArch64GOTAtom(_file, ".got.plt");
#ifndef NDEBUG
_null->_name = "__got_null";
#endif
}
return _null;
}
const GOTAtom *getGOT(const DefinedAtom *da) {
auto got = _gotMap.find(da);
if (got == _gotMap.end()) {
auto g = new (_file._alloc) AArch64GOTAtom(_file, ".got");
g->addReferenceELF_AArch64(R_AARCH64_ABS64, 0, da, 0);
#ifndef NDEBUG
g->_name = "__got_";
g->_name += da->name();
#endif
_gotMap[da] = g;
_gotVector.push_back(g);
return g;
}
return got->second;
}
public:
AArch64RelocationPass(const ELFLinkingContext &ctx)
: _file(ctx), _ctx(ctx), _null(nullptr), _PLT0(nullptr), _got0(nullptr),
_got1(nullptr) {}
/// \brief Do the pass.
///
/// The goal here is to first process each reference individually. Each call
/// to handleReference may modify the reference itself and/or create new
/// atoms which must be stored in one of the maps below.
///
/// After all references are handled, the atoms created during that are all
/// added to mf.
void perform(std::unique_ptr<MutableFile> &mf) override {
ScopedTask task(getDefaultDomain(), "AArch64 GOT/PLT Pass");
DEBUG_WITH_TYPE(
"AArch64", llvm::dbgs() << "Undefined Atoms"
<< "\n";
for (const auto &atom
: mf->undefined()) {
llvm::dbgs() << " Name of Atom: " << atom->name().str() << "\n";
} llvm::dbgs()
<< "Shared Library Atoms"
<< "\n";
for (const auto &atom
: mf->sharedLibrary()) {
llvm::dbgs() << " Name of Atom: " << atom->name().str() << "\n";
} llvm::dbgs()
<< "Absolute Atoms"
<< "\n";
for (const auto &atom
: mf->absolute()) {
llvm::dbgs() << " Name of Atom: " << atom->name().str() << "\n";
}
// Process all references.
llvm::dbgs()
<< "Defined Atoms"
<< "\n");
for (const auto &atom : mf->defined()) {
for (const auto &ref : *atom) {
handleReference(*atom, *ref);
}
}
// Add all created atoms to the link.
uint64_t ordinal = 0;
if (_PLT0) {
_PLT0->setOrdinal(ordinal++);
mf->addAtom(*_PLT0);
}
for (auto &plt : _pltVector) {
plt->setOrdinal(ordinal++);
mf->addAtom(*plt);
}
if (_null) {
_null->setOrdinal(ordinal++);
mf->addAtom(*_null);
}
if (_PLT0) {
_got0->setOrdinal(ordinal++);
_got1->setOrdinal(ordinal++);
mf->addAtom(*_got0);
mf->addAtom(*_got1);
}
for (auto &got : _gotVector) {
got->setOrdinal(ordinal++);
mf->addAtom(*got);
}
for (auto obj : _objectVector) {
obj->setOrdinal(ordinal++);
mf->addAtom(*obj);
}
}
protected:
/// \brief Owner of all the Atoms created by this pass.
ELFPassFile _file;
const ELFLinkingContext &_ctx;
/// \brief Map Atoms to their GOT entries.
llvm::DenseMap<const Atom *, GOTAtom *> _gotMap;
/// \brief Map Atoms to their PLT entries.
llvm::DenseMap<const Atom *, PLTAtom *> _pltMap;
/// \brief Map Atoms to their Object entries.
llvm::DenseMap<const Atom *, ObjectAtom *> _objectMap;
/// \brief the list of GOT/PLT atoms
std::vector<GOTAtom *> _gotVector;
std::vector<PLTAtom *> _pltVector;
std::vector<ObjectAtom *> _objectVector;
/// \brief GOT entry that is always 0. Used for undefined weaks.
GOTAtom *_null;
/// \brief The got and plt entries for .PLT0. This is used to call into the
/// dynamic linker for symbol resolution.
/// @{
PLT0Atom *_PLT0;
GOTAtom *_got0;
GOTAtom *_got1;
/// @}
};
/// This implements the static relocation model. Meaning GOT and PLT entries are
/// not created for references that can be directly resolved. These are
/// converted to a direct relocation. For entries that do require a GOT or PLT
/// entry, that entry is statically bound.
///
/// TLS always assumes module 1 and attempts to remove indirection.
class AArch64StaticRelocationPass final
: public AArch64RelocationPass<AArch64StaticRelocationPass> {
public:
AArch64StaticRelocationPass(const elf::AArch64LinkingContext &ctx)
: AArch64RelocationPass(ctx) {}
std::error_code handlePlain(const Reference &ref) { return handleIFUNC(ref); }
std::error_code handlePLT32(const Reference &ref) {
// __tls_get_addr is handled elsewhere.
if (ref.target() && ref.target()->name() == "__tls_get_addr") {
const_cast<Reference &>(ref).setKindValue(R_AARCH64_NONE);
return std::error_code();
}
// Static code doesn't need PLTs.
const_cast<Reference &>(ref).setKindValue(R_AARCH64_PREL32);
// Handle IFUNC.
if (const DefinedAtom *da =
dyn_cast_or_null<const DefinedAtom>(ref.target()))
if (da->contentType() == DefinedAtom::typeResolver)
return handleIFUNC(ref);
return std::error_code();
}
std::error_code handleGOT(const Reference &ref) {
if (isa<UndefinedAtom>(ref.target()))
const_cast<Reference &>(ref).setTarget(getNullGOT());
else if (const DefinedAtom *da = dyn_cast<const DefinedAtom>(ref.target()))
const_cast<Reference &>(ref).setTarget(getGOT(da));
return std::error_code();
}
};
class AArch64DynamicRelocationPass final
: public AArch64RelocationPass<AArch64DynamicRelocationPass> {
public:
AArch64DynamicRelocationPass(const elf::AArch64LinkingContext &ctx)
: AArch64RelocationPass(ctx) {}
const PLT0Atom *getPLT0() {
if (_PLT0)
return _PLT0;
// Fill in the null entry.
getNullGOT();
_PLT0 = new (_file._alloc) AArch64PLT0Atom(_file);
_got0 = new (_file._alloc) AArch64GOTAtom(_file, ".got.plt");
_got1 = new (_file._alloc) AArch64GOTAtom(_file, ".got.plt");
_PLT0->addReferenceELF_AArch64(R_AARCH64_ADR_GOT_PAGE, 4, _got0, 0);
_PLT0->addReferenceELF_AArch64(R_AARCH64_LD64_GOT_LO12_NC, 8, _got1, 0);
_PLT0->addReferenceELF_AArch64(ADD_AARCH64_GOTRELINDEX, 12, _got1, 0);
#ifndef NDEBUG
_got0->_name = "__got0";
_got1->_name = "__got1";
#endif
return _PLT0;
}
const PLTAtom *getPLTEntry(const Atom *a) {
auto plt = _pltMap.find(a);
if (plt != _pltMap.end())
return plt->second;
auto ga = new (_file._alloc) AArch64GOTAtom(_file, ".got.plt");
ga->addReferenceELF_AArch64(R_AARCH64_JUMP_SLOT, 0, a, 0);
auto pa = new (_file._alloc) AArch64PLTAtom(_file, ".plt");
pa->addReferenceELF_AArch64(R_AARCH64_ADR_GOT_PAGE, 0, ga, 0);
pa->addReferenceELF_AArch64(R_AARCH64_LD64_GOT_LO12_NC, 4, ga, 0);
pa->addReferenceELF_AArch64(ADD_AARCH64_GOTRELINDEX, 8, ga, 0);
pa->addReferenceELF_AArch64(R_AARCH64_NONE, 12, getPLT0(), 0);
// Set the starting address of the got entry to the first instruction in
// the plt0 entry.
ga->addReferenceELF_AArch64(R_AARCH64_ABS32, 0, pa, 0);
#ifndef NDEBUG
ga->_name = "__got_";
ga->_name += a->name();
pa->_name = "__plt_";
pa->_name += a->name();
#endif
_gotMap[a] = ga;
_pltMap[a] = pa;
_gotVector.push_back(ga);
_pltVector.push_back(pa);
return pa;
}
const ObjectAtom *getObjectEntry(const SharedLibraryAtom *a) {
auto obj = _objectMap.find(a);
if (obj != _objectMap.end())
return obj->second;
auto oa = new (_file._alloc) ObjectAtom(_file);
// This needs to point to the atom that we just created.
oa->addReferenceELF_AArch64(R_AARCH64_COPY, 0, oa, 0);
oa->_name = a->name();
oa->_size = a->size();
_objectMap[a] = oa;
_objectVector.push_back(oa);
return oa;
}
std::error_code handlePlain(const Reference &ref) {
if (!ref.target())
return std::error_code();
if (auto sla = dyn_cast<SharedLibraryAtom>(ref.target())) {
if (sla->type() == SharedLibraryAtom::Type::Data)
const_cast<Reference &>(ref).setTarget(getObjectEntry(sla));
else if (sla->type() == SharedLibraryAtom::Type::Code)
const_cast<Reference &>(ref).setTarget(getPLTEntry(sla));
} else
return handleIFUNC(ref);
return std::error_code();
}
std::error_code handlePLT32(const Reference &ref) {
// Turn this into a PC32 to the PLT entry.
const_cast<Reference &>(ref).setKindValue(R_AARCH64_PREL32);
// Handle IFUNC.
if (const DefinedAtom *da =
dyn_cast_or_null<const DefinedAtom>(ref.target()))
if (da->contentType() == DefinedAtom::typeResolver)
return handleIFUNC(ref);
if (isa<const SharedLibraryAtom>(ref.target()))
const_cast<Reference &>(ref).setTarget(getPLTEntry(ref.target()));
return std::error_code();
}
const GOTAtom *getSharedGOT(const SharedLibraryAtom *sla) {
auto got = _gotMap.find(sla);
if (got == _gotMap.end()) {
auto g = new (_file._alloc) AArch64GOTAtom(_file, ".got.dyn");
g->addReferenceELF_AArch64(R_AARCH64_GLOB_DAT, 0, sla, 0);
#ifndef NDEBUG
g->_name = "__got_";
g->_name += sla->name();
#endif
_gotMap[sla] = g;
_gotVector.push_back(g);
return g;
}
return got->second;
}
std::error_code handleGOT(const Reference &ref) {
if (isa<UndefinedAtom>(ref.target()))
const_cast<Reference &>(ref).setTarget(getNullGOT());
else if (const DefinedAtom *da = dyn_cast<const DefinedAtom>(ref.target()))
const_cast<Reference &>(ref).setTarget(getGOT(da));
else if (const auto sla = dyn_cast<const SharedLibraryAtom>(ref.target()))
const_cast<Reference &>(ref).setTarget(getSharedGOT(sla));
return std::error_code();
}
};
} // end anon namespace
std::unique_ptr<Pass>
lld::elf::createAArch64RelocationPass(const AArch64LinkingContext &ctx) {
switch (ctx.getOutputELFType()) {
case llvm::ELF::ET_EXEC:
if (ctx.isDynamic())
return std::unique_ptr<Pass>(new AArch64DynamicRelocationPass(ctx));
else
return std::unique_ptr<Pass>(new AArch64StaticRelocationPass(ctx));
case llvm::ELF::ET_DYN:
return std::unique_ptr<Pass>(new AArch64DynamicRelocationPass(ctx));
case llvm::ELF::ET_REL:
return std::unique_ptr<Pass>();
default:
llvm_unreachable("Unhandled output file type");
}
}