1 //===- Relocations.cpp ----------------------------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "Relocations.h" 10 #include "ConcatOutputSection.h" 11 #include "Symbols.h" 12 #include "SyntheticSections.h" 13 #include "Target.h" 14 15 #include "lld/Common/ErrorHandler.h" 16 17 using namespace llvm; 18 using namespace lld; 19 using namespace lld::macho; 20 21 static_assert(sizeof(void *) != 8 || sizeof(Reloc) == 24, 22 "Try to minimize Reloc's size; we create many instances"); 23 24 InputSection *Reloc::getReferentInputSection() const { 25 if (const auto *sym = referent.dyn_cast<Symbol *>()) { 26 if (const auto *d = dyn_cast<Defined>(sym)) 27 return d->isec; 28 return nullptr; 29 } else { 30 return referent.get<InputSection *>(); 31 } 32 } 33 34 bool macho::validateSymbolRelocation(const Symbol *sym, 35 const InputSection *isec, const Reloc &r) { 36 const RelocAttrs &relocAttrs = target->getRelocAttrs(r.type); 37 bool valid = true; 38 auto message = [&](const Twine &diagnostic) { 39 valid = false; 40 return (isec->getLocation(r.offset) + ": " + relocAttrs.name + 41 " relocation " + diagnostic) 42 .str(); 43 }; 44 45 if (relocAttrs.hasAttr(RelocAttrBits::TLV) != sym->isTlv()) 46 error(message(Twine("requires that symbol ") + sym->getName() + " " + 47 (sym->isTlv() ? "not " : "") + "be thread-local")); 48 49 return valid; 50 } 51 52 // Given an offset in the output buffer, figure out which ConcatInputSection (if 53 // any) maps to it. At the same time, update the offset such that it is relative 54 // to the InputSection rather than to the output buffer. 55 // 56 // Obtaining the InputSection allows us to have better error diagnostics. 57 // However, many of our relocation-handling methods do not take the InputSection 58 // as a parameter. Since we are already passing the buffer offsets to our Target 59 // methods, this function allows us to emit better errors without threading an 60 // additional InputSection argument through the call stack. 61 // 62 // This is implemented as a slow linear search through OutputSegments, 63 // OutputSections, and finally the InputSections themselves. However, this 64 // function should be called only on error paths, so some overhead is fine. 65 InputSection *macho::offsetToInputSection(uint64_t *off) { 66 for (OutputSegment *seg : outputSegments) { 67 if (*off < seg->fileOff || *off >= seg->fileOff + seg->fileSize) 68 continue; 69 70 const std::vector<OutputSection *> §ions = seg->getSections(); 71 size_t osecIdx = 0; 72 for (; osecIdx < sections.size(); ++osecIdx) 73 if (*off < sections[osecIdx]->fileOff) 74 break; 75 assert(osecIdx > 0); 76 // We should be only calling this function on offsets that belong to 77 // ConcatOutputSections. 78 auto *osec = cast<ConcatOutputSection>(sections[osecIdx - 1]); 79 *off -= osec->fileOff; 80 81 size_t isecIdx = 0; 82 for (; isecIdx < osec->inputs.size(); ++isecIdx) { 83 const ConcatInputSection *isec = osec->inputs[isecIdx]; 84 if (*off < isec->outSecOff) 85 break; 86 } 87 assert(isecIdx > 0); 88 ConcatInputSection *isec = osec->inputs[isecIdx - 1]; 89 *off -= isec->outSecOff; 90 return isec; 91 } 92 return nullptr; 93 } 94 95 void macho::reportRangeError(void *loc, const Reloc &r, const Twine &v, 96 uint8_t bits, int64_t min, uint64_t max) { 97 std::string hint; 98 uint64_t off = reinterpret_cast<const uint8_t *>(loc) - in.bufferStart; 99 const InputSection *isec = offsetToInputSection(&off); 100 std::string locStr = isec ? isec->getLocation(off) : "(invalid location)"; 101 if (auto *sym = r.referent.dyn_cast<Symbol *>()) 102 hint = "; references " + toString(*sym); 103 error(locStr + ": relocation " + target->getRelocAttrs(r.type).name + 104 " is out of range: " + v + " is not in [" + Twine(min) + ", " + 105 Twine(max) + "]" + hint); 106 } 107 108 void macho::reportRangeError(void *loc, SymbolDiagnostic d, const Twine &v, 109 uint8_t bits, int64_t min, uint64_t max) { 110 // FIXME: should we use `loc` somehow to provide a better error message? 111 std::string hint; 112 if (d.symbol) 113 hint = "; references " + toString(*d.symbol); 114 error(d.reason + " is out of range: " + v + " is not in [" + Twine(min) + 115 ", " + Twine(max) + "]" + hint); 116 } 117 118 const RelocAttrs macho::invalidRelocAttrs{"INVALID", RelocAttrBits::_0}; 119