llvm-project

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//===- Relocations.cpp ----------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "Relocations.h"
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#include "ConcatOutputSection.h"
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#include "Symbols.h"
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#include "SyntheticSections.h"
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#include "Target.h"
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#include "lld/Common/ErrorHandler.h"
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using namespace llvm;
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using namespace lld;
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using namespace lld::macho;
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static_assert(sizeof(void *) != 8 || sizeof(Reloc) == 24,
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              "Try to minimize Reloc's size; we create many instances");
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InputSection *Reloc::getReferentInputSection() const {
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  if (const auto *sym = referent.dyn_cast<Symbol *>()) {
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    if (const auto *d = dyn_cast<Defined>(sym))
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      return d->isec();
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    return nullptr;
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  } else {
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    return referent.get<InputSection *>();
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  }
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}
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bool macho::validateSymbolRelocation(const Symbol *sym,
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                                     const InputSection *isec, const Reloc &r) {
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  const RelocAttrs &relocAttrs = target->getRelocAttrs(r.type);
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  bool valid = true;
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  auto message = [&](const Twine &diagnostic) {
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    valid = false;
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    return (isec->getLocation(r.offset) + ": " + relocAttrs.name +
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            " relocation " + diagnostic)
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        .str();
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  };
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  if (relocAttrs.hasAttr(RelocAttrBits::TLV) != sym->isTlv())
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    error(message(Twine("requires that symbol ") + sym->getName() + " " +
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                  (sym->isTlv() ? "not " : "") + "be thread-local"));
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  return valid;
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}
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// Given an offset in the output buffer, figure out which ConcatInputSection (if
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// any) maps to it. At the same time, update the offset such that it is relative
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// to the InputSection rather than to the output buffer.
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//
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// Obtaining the InputSection allows us to have better error diagnostics.
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// However, many of our relocation-handling methods do not take the InputSection
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// as a parameter. Since we are already passing the buffer offsets to our Target
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// methods, this function allows us to emit better errors without threading an
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// additional InputSection argument through the call stack.
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//
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// This is implemented as a slow linear search through OutputSegments,
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// OutputSections, and finally the InputSections themselves. However, this
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// function should be called only on error paths, so some overhead is fine.
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InputSection *macho::offsetToInputSection(uint64_t *off) {
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  for (OutputSegment *seg : outputSegments) {
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    if (*off < seg->fileOff || *off >= seg->fileOff + seg->fileSize)
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      continue;
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    const std::vector<OutputSection *> &sections = seg->getSections();
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    size_t osecIdx = 0;
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    for (; osecIdx < sections.size(); ++osecIdx)
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      if (*off < sections[osecIdx]->fileOff)
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        break;
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    assert(osecIdx > 0);
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    // We should be only calling this function on offsets that belong to
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    // ConcatOutputSections.
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    auto *osec = cast<ConcatOutputSection>(sections[osecIdx - 1]);
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    *off -= osec->fileOff;
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    size_t isecIdx = 0;
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    for (; isecIdx < osec->inputs.size(); ++isecIdx) {
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      const ConcatInputSection *isec = osec->inputs[isecIdx];
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      if (*off < isec->outSecOff)
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        break;
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    }
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    assert(isecIdx > 0);
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    ConcatInputSection *isec = osec->inputs[isecIdx - 1];
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    *off -= isec->outSecOff;
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    return isec;
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  }
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  return nullptr;
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}
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void macho::reportRangeError(void *loc, const Reloc &r, const Twine &v,
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                             uint8_t bits, int64_t min, uint64_t max) {
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  std::string hint;
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  uint64_t off = reinterpret_cast<const uint8_t *>(loc) - in.bufferStart;
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  const InputSection *isec = offsetToInputSection(&off);
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  std::string locStr = isec ? isec->getLocation(off) : "(invalid location)";
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  if (auto *sym = r.referent.dyn_cast<Symbol *>())
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    hint = "; references " + toString(*sym);
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  error(locStr + ": relocation " + target->getRelocAttrs(r.type).name +
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        " is out of range: " + v + " is not in [" + Twine(min) + ", " +
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        Twine(max) + "]" + hint);
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}
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void macho::reportRangeError(void *loc, SymbolDiagnostic d, const Twine &v,
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                             uint8_t bits, int64_t min, uint64_t max) {
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  // FIXME: should we use `loc` somehow to provide a better error message?
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  std::string hint;
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  if (d.symbol)
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    hint = "; references " + toString(*d.symbol);
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  error(d.reason + " is out of range: " + v + " is not in [" + Twine(min) +
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        ", " + Twine(max) + "]" + hint);
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}
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const RelocAttrs macho::invalidRelocAttrs{"INVALID", RelocAttrBits::_0};
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