144 lines · cpp
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-exception6//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 17using namespace llvm;18using namespace lld;19using namespace lld::macho;20 21static_assert(sizeof(void *) != 8 || sizeof(Reloc) == 24,22 "Try to minimize Reloc's size; we create many instances");23 24InputSection *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 cast<InputSection *>(referent);31 }32}33 34StringRef Reloc::getReferentString() const {35 if (auto *isec = dyn_cast<InputSection *>(referent)) {36 const auto *cisec = dyn_cast<CStringInputSection>(isec);37 assert(cisec && "referent must be a CStringInputSection");38 return cisec->getStringRefAtOffset(addend);39 }40 41 auto *sym = dyn_cast<Defined>(cast<Symbol *>(referent));42 assert(sym && "referent must be a Defined symbol");43 44 auto *symIsec = sym->isec();45 auto symOffset = sym->value + addend;46 47 if (auto *s = dyn_cast_or_null<CStringInputSection>(symIsec))48 return s->getStringRefAtOffset(symOffset);49 50 if (isa<ConcatInputSection>(symIsec)) {51 auto strData = symIsec->data.slice(symOffset);52 const char *pszData = reinterpret_cast<const char *>(strData.data());53 return StringRef(pszData, strnlen(pszData, strData.size()));54 }55 56 llvm_unreachable("unknown reference section in getReferentString");57}58 59bool macho::validateSymbolRelocation(const Symbol *sym,60 const InputSection *isec, const Reloc &r) {61 const RelocAttrs &relocAttrs = target->getRelocAttrs(r.type);62 bool valid = true;63 auto message = [&](const Twine &diagnostic) {64 valid = false;65 return (isec->getLocation(r.offset) + ": " + relocAttrs.name +66 " relocation " + diagnostic)67 .str();68 };69 70 if (relocAttrs.hasAttr(RelocAttrBits::TLV) != sym->isTlv())71 error(message(Twine("requires that symbol ") + sym->getName() + " " +72 (sym->isTlv() ? "not " : "") + "be thread-local"));73 74 return valid;75}76 77// Given an offset in the output buffer, figure out which ConcatInputSection (if78// any) maps to it. At the same time, update the offset such that it is relative79// to the InputSection rather than to the output buffer.80//81// Obtaining the InputSection allows us to have better error diagnostics.82// However, many of our relocation-handling methods do not take the InputSection83// as a parameter. Since we are already passing the buffer offsets to our Target84// methods, this function allows us to emit better errors without threading an85// additional InputSection argument through the call stack.86//87// This is implemented as a slow linear search through OutputSegments,88// OutputSections, and finally the InputSections themselves. However, this89// function should be called only on error paths, so some overhead is fine.90InputSection *macho::offsetToInputSection(uint64_t *off) {91 for (OutputSegment *seg : outputSegments) {92 if (*off < seg->fileOff || *off >= seg->fileOff + seg->fileSize)93 continue;94 95 const std::vector<OutputSection *> §ions = seg->getSections();96 size_t osecIdx = 0;97 for (; osecIdx < sections.size(); ++osecIdx)98 if (*off < sections[osecIdx]->fileOff)99 break;100 assert(osecIdx > 0);101 // We should be only calling this function on offsets that belong to102 // ConcatOutputSections.103 auto *osec = cast<ConcatOutputSection>(sections[osecIdx - 1]);104 *off -= osec->fileOff;105 106 size_t isecIdx = 0;107 for (; isecIdx < osec->inputs.size(); ++isecIdx) {108 const ConcatInputSection *isec = osec->inputs[isecIdx];109 if (*off < isec->outSecOff)110 break;111 }112 assert(isecIdx > 0);113 ConcatInputSection *isec = osec->inputs[isecIdx - 1];114 *off -= isec->outSecOff;115 return isec;116 }117 return nullptr;118}119 120void macho::reportRangeError(void *loc, const Reloc &r, const Twine &v,121 uint8_t bits, int64_t min, uint64_t max) {122 std::string hint;123 uint64_t off = reinterpret_cast<const uint8_t *>(loc) - in.bufferStart;124 const InputSection *isec = offsetToInputSection(&off);125 std::string locStr = isec ? isec->getLocation(off) : "(invalid location)";126 if (auto *sym = r.referent.dyn_cast<Symbol *>())127 hint = "; references " + toString(*sym);128 error(locStr + ": relocation " + target->getRelocAttrs(r.type).name +129 " is out of range: " + v + " is not in [" + Twine(min) + ", " +130 Twine(max) + "]" + hint);131}132 133void macho::reportRangeError(void *loc, SymbolDiagnostic d, const Twine &v,134 uint8_t bits, int64_t min, uint64_t max) {135 // FIXME: should we use `loc` somehow to provide a better error message?136 std::string hint;137 if (d.symbol)138 hint = "; references " + toString(*d.symbol);139 error(d.reason + " is out of range: " + v + " is not in [" + Twine(min) +140 ", " + Twine(max) + "]" + hint);141}142 143const RelocAttrs macho::invalidRelocAttrs{"INVALID", RelocAttrBits::_0};144