1 //===- lib/ReaderWriter/MachO/TLVPass.cpp -----------------------*- C++ -*-===//
2 //
3 // The LLVM Linker
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 ///
10 /// \file
11 /// This linker pass transforms all TLV references to real references.
12 ///
13 //===----------------------------------------------------------------------===//
14
15 #include "ArchHandler.h"
16 #include "File.h"
17 #include "MachOPasses.h"
18 #include "lld/Core/Simple.h"
19 #include "llvm/ADT/STLExtras.h"
20 #include "llvm/Support/Debug.h"
21
22 namespace lld {
23 namespace mach_o {
24
25 //
26 // TLVP Entry Atom created by the TLV pass.
27 //
28 class TLVPEntryAtom : public SimpleDefinedAtom {
29 public:
TLVPEntryAtom(const File & file,bool is64,StringRef name)30 TLVPEntryAtom(const File &file, bool is64, StringRef name)
31 : SimpleDefinedAtom(file), _is64(is64), _name(name) {}
32
33 ~TLVPEntryAtom() override = default;
34
contentType() const35 ContentType contentType() const override {
36 return DefinedAtom::typeTLVInitializerPtr;
37 }
38
alignment() const39 Alignment alignment() const override {
40 return _is64 ? 8 : 4;
41 }
42
size() const43 uint64_t size() const override {
44 return _is64 ? 8 : 4;
45 }
46
permissions() const47 ContentPermissions permissions() const override {
48 return DefinedAtom::permRW_;
49 }
50
rawContent() const51 ArrayRef<uint8_t> rawContent() const override {
52 static const uint8_t zeros[] =
53 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
54 return llvm::makeArrayRef(zeros, size());
55 }
56
slotName() const57 StringRef slotName() const {
58 return _name;
59 }
60
61 private:
62 const bool _is64;
63 StringRef _name;
64 };
65
66 class TLVPass : public Pass {
67 public:
TLVPass(const MachOLinkingContext & context)68 TLVPass(const MachOLinkingContext &context)
69 : _ctx(context), _archHandler(_ctx.archHandler()),
70 _file(*_ctx.make_file<MachOFile>("<mach-o TLV pass>")) {
71 _file.setOrdinal(_ctx.getNextOrdinalAndIncrement());
72 }
73
74 private:
perform(SimpleFile & mergedFile)75 llvm::Error perform(SimpleFile &mergedFile) override {
76 bool allowTLV = _ctx.minOS("10.7", "1.0");
77
78 for (const DefinedAtom *atom : mergedFile.defined()) {
79 for (const Reference *ref : *atom) {
80 if (!_archHandler.isTLVAccess(*ref))
81 continue;
82
83 if (!allowTLV)
84 return llvm::make_error<GenericError>(
85 "targeted OS version does not support use of thread local "
86 "variables in " + atom->name() + " for architecture " +
87 _ctx.archName());
88
89 const Atom *target = ref->target();
90 assert(target != nullptr);
91
92 const DefinedAtom *tlvpEntry = makeTLVPEntry(target);
93 const_cast<Reference*>(ref)->setTarget(tlvpEntry);
94 _archHandler.updateReferenceToTLV(ref);
95 }
96 }
97
98 std::vector<const TLVPEntryAtom*> entries;
99 entries.reserve(_targetToTLVP.size());
100 for (auto &it : _targetToTLVP)
101 entries.push_back(it.second);
102 std::sort(entries.begin(), entries.end(),
103 [](const TLVPEntryAtom *lhs, const TLVPEntryAtom *rhs) {
104 return (lhs->slotName().compare(rhs->slotName()) < 0);
105 });
106
107 for (const TLVPEntryAtom *slot : entries)
108 mergedFile.addAtom(*slot);
109
110 return llvm::Error::success();
111 }
112
makeTLVPEntry(const Atom * target)113 const DefinedAtom *makeTLVPEntry(const Atom *target) {
114 auto pos = _targetToTLVP.find(target);
115
116 if (pos != _targetToTLVP.end())
117 return pos->second;
118
119 auto *tlvpEntry = new (_file.allocator())
120 TLVPEntryAtom(_file, _ctx.is64Bit(), target->name());
121 _targetToTLVP[target] = tlvpEntry;
122 const ArchHandler::ReferenceInfo &nlInfo =
123 _archHandler.stubInfo().nonLazyPointerReferenceToBinder;
124 tlvpEntry->addReference(Reference::KindNamespace::mach_o, nlInfo.arch,
125 nlInfo.kind, 0, target, 0);
126 return tlvpEntry;
127 }
128
129 const MachOLinkingContext &_ctx;
130 mach_o::ArchHandler &_archHandler;
131 MachOFile &_file;
132 llvm::DenseMap<const Atom*, const TLVPEntryAtom*> _targetToTLVP;
133 };
134
addTLVPass(PassManager & pm,const MachOLinkingContext & ctx)135 void addTLVPass(PassManager &pm, const MachOLinkingContext &ctx) {
136 assert(ctx.needsTLVPass());
137 pm.add(llvm::make_unique<TLVPass>(ctx));
138 }
139
140 } // end namesapce mach_o
141 } // end namesapce lld
142