[lld] r221654 - [mach-o] Fix lazy binding offsets
Nick Kledzik
kledzik at apple.com
Mon Nov 10 17:31:18 PST 2014
Author: kledzik
Date: Mon Nov 10 19:31:18 2014
New Revision: 221654
URL: http://llvm.org/viewvc/llvm-project?rev=221654&view=rev
Log:
[mach-o] Fix lazy binding offsets
The way lazy binding works in mach-o is that the linker generates a helper
function and has the stub (PLT) initially jump to it. The helper function
pushes an extra parameter then jumps into dyld. The extra parameter is an
offset into the lazy binding info where dyld will find the information about
which symbol to bind and way lazy binding pointer to update.
Modified:
lld/trunk/lib/ReaderWriter/MachO/ArchHandler_arm.cpp
lld/trunk/lib/ReaderWriter/MachO/ArchHandler_arm64.cpp
lld/trunk/lib/ReaderWriter/MachO/ArchHandler_x86.cpp
lld/trunk/lib/ReaderWriter/MachO/ArchHandler_x86_64.cpp
lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp
lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp
lld/trunk/lib/ReaderWriter/MachO/StubsPass.cpp
lld/trunk/test/mach-o/lazy-bind-x86_64.yaml
Modified: lld/trunk/lib/ReaderWriter/MachO/ArchHandler_arm.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/MachO/ArchHandler_arm.cpp?rev=221654&r1=221653&r2=221654&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/MachO/ArchHandler_arm.cpp (original)
+++ lld/trunk/lib/ReaderWriter/MachO/ArchHandler_arm.cpp Mon Nov 10 19:31:18 2014
@@ -998,9 +998,11 @@ void ArchHandler_arm::applyFixupFinal(co
*loc32 = targetAddress - fixupAddress + ref.addend();
break;
case lazyPointer:
- case lazyImmediateLocation:
// do nothing
break;
+ case lazyImmediateLocation:
+ *loc32 = ref.addend();
+ break;
case invalid:
llvm_unreachable("invalid ARM Reference Kind");
break;
Modified: lld/trunk/lib/ReaderWriter/MachO/ArchHandler_arm64.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/MachO/ArchHandler_arm64.cpp?rev=221654&r1=221653&r2=221654&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/MachO/ArchHandler_arm64.cpp (original)
+++ lld/trunk/lib/ReaderWriter/MachO/ArchHandler_arm64.cpp Mon Nov 10 19:31:18 2014
@@ -573,9 +573,11 @@ void ArchHandler_arm64::applyFixupFinal(
*loc32 = (targetAddress - fixupAddress) + ref.addend();
return;
case lazyPointer:
- case lazyImmediateLocation:
// Do nothing
return;
+ case lazyImmediateLocation:
+ *loc32 = ref.addend();
+ return;
case invalid:
// Fall into llvm_unreachable().
break;
Modified: lld/trunk/lib/ReaderWriter/MachO/ArchHandler_x86.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/MachO/ArchHandler_x86.cpp?rev=221654&r1=221653&r2=221654&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/MachO/ArchHandler_x86.cpp (original)
+++ lld/trunk/lib/ReaderWriter/MachO/ArchHandler_x86.cpp Mon Nov 10 19:31:18 2014
@@ -461,9 +461,11 @@ void ArchHandler_x86::applyFixupFinal(co
case modeCode:
case modeData:
case lazyPointer:
- case lazyImmediateLocation:
// do nothing
break;
+ case lazyImmediateLocation:
+ *loc32 = ref.addend();
+ break;
default:
llvm_unreachable("invalid x86 Reference Kind");
break;
Modified: lld/trunk/lib/ReaderWriter/MachO/ArchHandler_x86_64.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/MachO/ArchHandler_x86_64.cpp?rev=221654&r1=221653&r2=221654&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/MachO/ArchHandler_x86_64.cpp (original)
+++ lld/trunk/lib/ReaderWriter/MachO/ArchHandler_x86_64.cpp Mon Nov 10 19:31:18 2014
@@ -521,8 +521,10 @@ void ArchHandler_x86_64::applyFixupFinal
*loc32 = fixupAddress - targetAddress + ref.addend();
return;
case lazyPointer:
+ // Do nothing
+ return;
case lazyImmediateLocation:
- // do nothing
+ *loc32 = ref.addend();
return;
case imageOffset:
case imageOffsetGot:
Modified: lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp?rev=221654&r1=221653&r2=221654&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp (original)
+++ lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileBinaryWriter.cpp Mon Nov 10 19:31:18 2014
@@ -125,6 +125,12 @@ private:
void append_uleb128(uint64_t value) {
llvm::encodeULEB128(value, _ostream);
}
+ void append_uleb128Fixed(uint64_t value, unsigned byteCount) {
+ unsigned min = llvm::getULEB128Size(value);
+ assert(min <= byteCount);
+ unsigned pad = byteCount - min;
+ llvm::encodeULEB128(value, _ostream, pad);
+ }
void append_sleb128(int64_t value) {
llvm::encodeSLEB128(value, _ostream);
}
@@ -999,6 +1005,7 @@ void MachOFileLayout::buildRebaseInfo()
void MachOFileLayout::buildBindInfo() {
// TODO: compress bind info.
+ uint64_t lastAddend = 0;
for (const BindLocation& entry : _file.bindingInfo) {
_bindingInfo.append_byte(BIND_OPCODE_SET_TYPE_IMM | entry.kind);
_bindingInfo.append_byte(BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB
@@ -1007,9 +1014,10 @@ void MachOFileLayout::buildBindInfo() {
_bindingInfo.append_byte(BIND_OPCODE_SET_DYLIB_ORDINAL_IMM | entry.ordinal);
_bindingInfo.append_byte(BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM);
_bindingInfo.append_string(entry.symbolName);
- if (entry.addend != 0) {
+ if (entry.addend != lastAddend) {
_bindingInfo.append_byte(BIND_OPCODE_SET_ADDEND_SLEB);
_bindingInfo.append_sleb128(entry.addend);
+ lastAddend = entry.addend;
}
_bindingInfo.append_byte(BIND_OPCODE_DO_BIND);
}
@@ -1022,11 +1030,12 @@ void MachOFileLayout::buildLazyBindInfo(
_lazyBindingInfo.append_byte(BIND_OPCODE_SET_TYPE_IMM | entry.kind);
_lazyBindingInfo.append_byte(BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB
| entry.segIndex);
- _lazyBindingInfo.append_uleb128(entry.segOffset);
+ _lazyBindingInfo.append_uleb128Fixed(entry.segOffset, 5);
_lazyBindingInfo.append_byte(BIND_OPCODE_SET_DYLIB_ORDINAL_IMM | entry.ordinal);
_lazyBindingInfo.append_byte(BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM);
_lazyBindingInfo.append_string(entry.symbolName);
_lazyBindingInfo.append_byte(BIND_OPCODE_DO_BIND);
+ _lazyBindingInfo.append_byte(BIND_OPCODE_DONE);
}
_lazyBindingInfo.append_byte(BIND_OPCODE_DONE);
_lazyBindingInfo.align(_is64 ? 8 : 4);
Modified: lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp?rev=221654&r1=221653&r2=221654&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp (original)
+++ lld/trunk/lib/ReaderWriter/MachO/MachONormalizedFileFromAtoms.cpp Mon Nov 10 19:31:18 2014
@@ -244,6 +244,7 @@ SectionInfo *Util::getFinalSection(Defin
switch (atomType) {
case DefinedAtom::typeCode:
case DefinedAtom::typeStub:
+ case DefinedAtom::typeStubHelper:
sectionAttrs = S_ATTR_PURE_INSTRUCTIONS;
break;
default:
Modified: lld/trunk/lib/ReaderWriter/MachO/StubsPass.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/MachO/StubsPass.cpp?rev=221654&r1=221653&r2=221654&view=diff
==============================================================================
--- lld/trunk/lib/ReaderWriter/MachO/StubsPass.cpp (original)
+++ lld/trunk/lib/ReaderWriter/MachO/StubsPass.cpp Mon Nov 10 19:31:18 2014
@@ -24,6 +24,7 @@
#include "lld/Core/Simple.h"
#include "lld/ReaderWriter/MachOLinkingContext.h"
#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallVector.h"
namespace lld {
@@ -107,7 +108,7 @@ private:
class StubAtom : public SimpleDefinedAtom {
public:
StubAtom(const File &file, const ArchHandler::StubInfo &stubInfo)
- : SimpleDefinedAtom(file), _stubInfo(stubInfo) { }
+ : SimpleDefinedAtom(file), _stubInfo(stubInfo){ }
ContentType contentType() const override {
return DefinedAtom::typeStub;
@@ -205,14 +206,8 @@ private:
class StubsPass : public Pass {
public:
StubsPass(const MachOLinkingContext &context)
- : _context(context)
- , _archHandler(_context.archHandler())
- , _stubInfo(_archHandler.stubInfo())
- , _file("<mach-o Stubs pass>")
- , _helperCommonAtom(nullptr)
- , _helperCacheNLPAtom(nullptr)
- , _helperBinderNLPAtom(nullptr) {
- }
+ : _context(context), _archHandler(_context.archHandler()),
+ _stubInfo(_archHandler.stubInfo()), _file("<mach-o Stubs pass>") { }
void perform(std::unique_ptr<MutableFile> &mergedFile) override {
@@ -230,7 +225,7 @@ public:
assert(target != nullptr);
if (isa<SharedLibraryAtom>(target)) {
// Calls to shared libraries go through stubs.
- replaceCalleeWithStub(target, ref);
+ _targetToUses[target].push_back(ref);
continue;
}
const DefinedAtom *defTarget = dyn_cast<DefinedAtom>(target);
@@ -238,47 +233,93 @@ public:
// Calls to interposable functions in same linkage unit must also go
// through a stub.
assert(defTarget->scope() != DefinedAtom::scopeTranslationUnit);
- replaceCalleeWithStub(target, ref);
+ _targetToUses[target].push_back(ref);
}
}
}
+
// Exit early if no stubs needed.
- if (_targetToStub.empty())
+ if (_targetToUses.empty())
return;
-
+
+ // First add help-common and GOT slots used by lazy binding.
+ SimpleDefinedAtom *helperCommonAtom =
+ new (_file.allocator()) StubHelperCommonAtom(_file, _stubInfo);
+ SimpleDefinedAtom *helperCacheNLPAtom =
+ new (_file.allocator()) NonLazyPointerAtom(_file, _context.is64Bit());
+ SimpleDefinedAtom *helperBinderNLPAtom =
+ new (_file.allocator()) NonLazyPointerAtom(_file, _context.is64Bit());
+ addReference(helperCommonAtom, _stubInfo.stubHelperCommonReferenceToCache,
+ helperCacheNLPAtom);
+ addOptReference(
+ helperCommonAtom, _stubInfo.stubHelperCommonReferenceToCache,
+ _stubInfo.optStubHelperCommonReferenceToCache, helperCacheNLPAtom);
+ addReference(helperCommonAtom, _stubInfo.stubHelperCommonReferenceToBinder,
+ helperBinderNLPAtom);
+ addOptReference(
+ helperCommonAtom, _stubInfo.stubHelperCommonReferenceToBinder,
+ _stubInfo.optStubHelperCommonReferenceToBinder, helperBinderNLPAtom);
+ mergedFile->addAtom(*helperCommonAtom);
+ mergedFile->addAtom(*helperBinderNLPAtom);
+ mergedFile->addAtom(*helperCacheNLPAtom);
+
// Add reference to dyld_stub_binder in libSystem.dylib
- if (_helperBinderNLPAtom) {
- bool found = false;
- for (const SharedLibraryAtom *atom : mergedFile->sharedLibrary()) {
- if (atom->name().equals(_stubInfo.binderSymbolName)) {
- addReference(_helperBinderNLPAtom,
- _stubInfo.nonLazyPointerReferenceToBinder, atom);
- found = true;
- break;
- }
+ bool binderFound = false;
+ for (const SharedLibraryAtom *atom : mergedFile->sharedLibrary()) {
+ if (atom->name().equals(_stubInfo.binderSymbolName)) {
+ addReference(helperBinderNLPAtom,
+ _stubInfo.nonLazyPointerReferenceToBinder, atom);
+ binderFound = true;
+ break;
}
- assert(found && "dyld_stub_binder not found");
- }
-
- // Add all stubs to master file.
- for (auto it : _targetToStub) {
- mergedFile->addAtom(*it.second);
- }
- // Add helper code atoms.
- mergedFile->addAtom(*_helperCommonAtom);
- for (const DefinedAtom *lp : _stubHelperAtoms) {
- mergedFile->addAtom(*lp);
}
- // Add GOT slots used for lazy binding.
- mergedFile->addAtom(*_helperBinderNLPAtom);
- mergedFile->addAtom(*_helperCacheNLPAtom);
- // Add all lazy pointers to master file.
- for (const DefinedAtom *lp : _lazyPointers) {
+ assert(binderFound && "dyld_stub_binder not found");
+
+ // Sort targets by name, so stubs and lazy pointers are consistent
+ std::vector<const Atom *> targetsNeedingStubs;
+ for (auto it : _targetToUses)
+ targetsNeedingStubs.push_back(it.first);
+ std::sort(targetsNeedingStubs.begin(), targetsNeedingStubs.end(),
+ [](const Atom * left, const Atom * right) {
+ return (left->name().compare(right->name()) < 0);
+ });
+
+ // Make and append stubs, lazy pointers, and helpers in alphabetical order.
+ unsigned lazyOffset = 0;
+ for (const Atom *target : targetsNeedingStubs) {
+ StubAtom *stub = new (_file.allocator()) StubAtom(_file, _stubInfo);
+ LazyPointerAtom *lp =
+ new (_file.allocator()) LazyPointerAtom(_file, _context.is64Bit());
+ StubHelperAtom *helper =
+ new (_file.allocator()) StubHelperAtom(_file, _stubInfo);
+
+ addReference(stub, _stubInfo.stubReferenceToLP, lp);
+ addOptReference(stub, _stubInfo.stubReferenceToLP,
+ _stubInfo.optStubReferenceToLP, lp);
+ addReference(lp, _stubInfo.lazyPointerReferenceToHelper, helper);
+ addReference(lp, _stubInfo.lazyPointerReferenceToFinal, target);
+ addReference(helper, _stubInfo.stubHelperReferenceToImm, helper);
+ addReferenceAddend(helper, _stubInfo.stubHelperReferenceToImm, helper,
+ lazyOffset);
+ addReference(helper, _stubInfo.stubHelperReferenceToHelperCommon,
+ helperCommonAtom);
+
+ mergedFile->addAtom(*stub);
mergedFile->addAtom(*lp);
+ mergedFile->addAtom(*helper);
+
+ // Update each reference to use stub.
+ for (const Reference *ref : _targetToUses[target]) {
+ assert(ref->target() == target);
+ // Switch call site to reference stub atom instead.
+ const_cast<Reference *>(ref)->setTarget(stub);
+ }
+
+ // Calculate new offset
+ lazyOffset += target->name().size() + 12;
}
}
-
private:
bool noTextRelocs() {
@@ -288,51 +329,6 @@ private:
bool isCallSite(const Reference &ref) {
return _archHandler.isCallSite(ref);
}
-
- void replaceCalleeWithStub(const Atom *target, const Reference *ref) {
- // Make file-format specific stub and other support atoms.
- const DefinedAtom *stub = this->getStub(*target);
- assert(stub != nullptr);
- // Switch call site to reference stub atom instead.
- const_cast<Reference *>(ref)->setTarget(stub);
- }
-
- const DefinedAtom* getStub(const Atom& target) {
- auto pos = _targetToStub.find(&target);
- if ( pos != _targetToStub.end() ) {
- // Reuse an existing stub.
- assert(pos->second != nullptr);
- return pos->second;
- }
- else {
- // There is no existing stub, so create a new one.
- return this->makeStub(target);
- }
- }
-
- const DefinedAtom* makeStub(const Atom &target) {
- SimpleDefinedAtom* stub = new (_file.allocator())
- StubAtom(_file, _stubInfo);
- SimpleDefinedAtom* lp = new (_file.allocator())
- LazyPointerAtom(_file, _context.is64Bit());
- SimpleDefinedAtom* helper = new (_file.allocator())
- StubHelperAtom(_file, _stubInfo);
-
- addReference(stub, _stubInfo.stubReferenceToLP, lp);
- addOptReference(stub, _stubInfo.stubReferenceToLP,
- _stubInfo.optStubReferenceToLP, lp);
- addReference(lp, _stubInfo.lazyPointerReferenceToHelper, helper);
- addReference(lp, _stubInfo.lazyPointerReferenceToFinal, &target);
- addReference(helper, _stubInfo.stubHelperReferenceToImm, helper);
- addReference(helper, _stubInfo.stubHelperReferenceToHelperCommon,
- helperCommon());
-
- _stubHelperAtoms.push_back(helper);
- _targetToStub[&target] = stub;
- _lazyPointers.push_back(lp);
-
- return stub;
- }
void addReference(SimpleDefinedAtom* atom,
const ArchHandler::ReferenceInfo &refInfo,
@@ -342,6 +338,13 @@ private:
target, refInfo.addend);
}
+ void addReferenceAddend(SimpleDefinedAtom *atom,
+ const ArchHandler::ReferenceInfo &refInfo,
+ const lld::Atom *target, uint64_t addend) {
+ atom->addReference(Reference::KindNamespace::mach_o, refInfo.arch,
+ refInfo.kind, refInfo.offset, target, addend);
+ }
+
void addOptReference(SimpleDefinedAtom* atom,
const ArchHandler::ReferenceInfo &refInfo,
const ArchHandler::OptionalRefInfo &optRef,
@@ -353,44 +356,14 @@ private:
target, optRef.addend);
}
- const DefinedAtom* helperCommon() {
- if ( !_helperCommonAtom ) {
- // Lazily create common helper code and data.
- _helperCommonAtom = new (_file.allocator())
- StubHelperCommonAtom(_file, _stubInfo);
- _helperCacheNLPAtom = new (_file.allocator())
- NonLazyPointerAtom(_file, _context.is64Bit());
- _helperBinderNLPAtom = new (_file.allocator())
- NonLazyPointerAtom(_file, _context.is64Bit());
- addReference(_helperCommonAtom,
- _stubInfo.stubHelperCommonReferenceToCache,
- _helperCacheNLPAtom);
- addOptReference(_helperCommonAtom,
- _stubInfo.stubHelperCommonReferenceToCache,
- _stubInfo.optStubHelperCommonReferenceToCache,
- _helperCacheNLPAtom);
- addReference(_helperCommonAtom,
- _stubInfo.stubHelperCommonReferenceToBinder,
- _helperBinderNLPAtom);
- addOptReference(_helperCommonAtom,
- _stubInfo.stubHelperCommonReferenceToBinder,
- _stubInfo.optStubHelperCommonReferenceToBinder,
- _helperBinderNLPAtom);
- }
- return _helperCommonAtom;
- }
-
+ typedef llvm::DenseMap<const Atom*,
+ llvm::SmallVector<const Reference *, 8>> TargetToUses;
const MachOLinkingContext &_context;
mach_o::ArchHandler &_archHandler;
const ArchHandler::StubInfo &_stubInfo;
MachOFile _file;
- llvm::DenseMap<const Atom*, const DefinedAtom*> _targetToStub;
- std::vector<const DefinedAtom*> _lazyPointers;
- std::vector<const DefinedAtom*> _stubHelperAtoms;
- SimpleDefinedAtom *_helperCommonAtom;
- SimpleDefinedAtom *_helperCacheNLPAtom;
- SimpleDefinedAtom *_helperBinderNLPAtom;
+ TargetToUses _targetToUses;
};
Modified: lld/trunk/test/mach-o/lazy-bind-x86_64.yaml
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/mach-o/lazy-bind-x86_64.yaml?rev=221654&r1=221653&r2=221654&view=diff
==============================================================================
--- lld/trunk/test/mach-o/lazy-bind-x86_64.yaml (original)
+++ lld/trunk/test/mach-o/lazy-bind-x86_64.yaml Mon Nov 10 19:31:18 2014
@@ -1,7 +1,8 @@
# RUN: lld -flavor darwin -arch x86_64 -macosx_version_min 10.8 %s -o %t \
-# RUN: %p/Inputs/libSystem.yaml \
-# RUN: && llvm-objdump -lazy-bind %t | FileCheck %s \
-# RUN: && llvm-nm -m %t | FileCheck --check-prefix=CHECK-NM %s
+# RUN: %p/Inputs/libSystem.yaml
+# RUN: llvm-objdump -lazy-bind %t | FileCheck %s
+# RUN: llvm-nm -m %t | FileCheck --check-prefix=CHECK-NM %s
+# RUN: llvm-objdump -disassemble %t | FileCheck --check-prefix=CHECK-HELPERS %s
#
# Test that correct two-level namespace ordinals are used for lazy bindings.
#
@@ -92,3 +93,9 @@ exports:
# CHECK-NM: (undefined) external _baz (from libbaz)
# CHECK-NM: (undefined) external _foo (from libfoo)
+
+# CHECK-HELPERS:Disassembly of section __TEXT,__stub_helper:
+# CHECK-HELPERS: 68 00 00 00 00 pushq $0
+# CHECK-HELPERS: 68 10 00 00 00 pushq $16
+# CHECK-HELPERS: 68 20 00 00 00 pushq $32
+
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