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1 //===- InputSection.cpp ---------------------------------------------------===//
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2 //
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3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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4 // See https://llvm.org/LICENSE.txt for license information.
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5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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6 //
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7 //===----------------------------------------------------------------------===//
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8
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9 #include "InputSection.h"
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10 #include "InputFiles.h"
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11 #include "OutputSegment.h"
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12 #include "Symbols.h"
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207
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13 #include "SyntheticSections.h"
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14 #include "Target.h"
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15 #include "Writer.h"
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16 #include "lld/Common/Memory.h"
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17 #include "llvm/Support/Endian.h"
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18
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19 using namespace llvm;
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20 using namespace llvm::MachO;
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21 using namespace llvm::support;
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22 using namespace lld;
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23 using namespace lld::macho;
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24
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25 std::vector<InputSection *> macho::inputSections;
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26
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27 uint64_t InputSection::getFileOffset() const {
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28 return parent->fileOff + outSecFileOff;
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29 }
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30
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31 uint64_t InputSection::getFileSize() const {
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32 return isZeroFill(flags) ? 0 : getSize();
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33 }
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34
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35 uint64_t InputSection::getVA() const { return parent->addr + outSecOff; }
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36
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37 static uint64_t resolveSymbolVA(const Symbol *sym, uint8_t type) {
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38 const RelocAttrs &relocAttrs = target->getRelocAttrs(type);
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39 if (relocAttrs.hasAttr(RelocAttrBits::BRANCH))
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40 return sym->resolveBranchVA();
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41 else if (relocAttrs.hasAttr(RelocAttrBits::GOT))
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42 return sym->resolveGotVA();
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43 else if (relocAttrs.hasAttr(RelocAttrBits::TLV))
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44 return sym->resolveTlvVA();
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45 return sym->getVA();
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46 }
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47
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48 void InputSection::writeTo(uint8_t *buf) {
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49 assert(!shouldOmitFromOutput());
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50
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51 if (getFileSize() == 0)
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52 return;
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53
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54 memcpy(buf, data.data(), data.size());
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55
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56 for (size_t i = 0; i < relocs.size(); i++) {
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57 const Reloc &r = relocs[i];
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58 uint8_t *loc = buf + r.offset;
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59 uint64_t referentVA = 0;
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60 if (target->hasAttr(r.type, RelocAttrBits::SUBTRAHEND)) {
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61 const Symbol *fromSym = r.referent.get<Symbol *>();
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62 const Reloc &minuend = relocs[++i];
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63 uint64_t minuendVA;
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64 if (const Symbol *toSym = minuend.referent.dyn_cast<Symbol *>())
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65 minuendVA = toSym->getVA();
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66 else {
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67 auto *referentIsec = minuend.referent.get<InputSection *>();
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68 assert(!referentIsec->shouldOmitFromOutput());
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69 minuendVA = referentIsec->getVA();
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70 }
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71 referentVA = minuendVA - fromSym->getVA() + minuend.addend;
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72 } else if (auto *referentSym = r.referent.dyn_cast<Symbol *>()) {
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73 if (target->hasAttr(r.type, RelocAttrBits::LOAD) &&
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74 !referentSym->isInGot())
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75 target->relaxGotLoad(loc, r.type);
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76 referentVA = resolveSymbolVA(referentSym, r.type);
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77
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78 if (isThreadLocalVariables(flags)) {
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79 // References from thread-local variable sections are treated as offsets
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80 // relative to the start of the thread-local data memory area, which
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81 // is initialized via copying all the TLV data sections (which are all
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82 // contiguous).
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83 if (isa<Defined>(referentSym))
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84 referentVA -= firstTLVDataSection->addr;
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85 }
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86 } else if (auto *referentIsec = r.referent.dyn_cast<InputSection *>()) {
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87 assert(!referentIsec->shouldOmitFromOutput());
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88 referentVA = referentIsec->getVA();
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89 }
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90 target->relocateOne(loc, r, referentVA + r.addend, getVA() + r.offset);
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91 }
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92 }
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93
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94 bool macho::isCodeSection(const InputSection *isec) {
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95 uint32_t type = isec->flags & SECTION_TYPE;
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96 if (type != S_REGULAR && type != S_COALESCED)
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97 return false;
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98
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99 uint32_t attr = isec->flags & SECTION_ATTRIBUTES_USR;
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100 if (attr == S_ATTR_PURE_INSTRUCTIONS)
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101 return true;
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102
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103 if (isec->segname == segment_names::text)
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104 return StringSwitch<bool>(isec->name)
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105 .Cases(section_names::textCoalNt, section_names::staticInit, true)
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106 .Default(false);
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107
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108 return false;
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109 }
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110
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111 std::string lld::toString(const InputSection *isec) {
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112 return (toString(isec->file) + ":(" + isec->name + ")").str();
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113 }
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