Пример #1
0
void InputSection::copyRelocations(uint8_t *Buf, ArrayRef<RelTy> Rels) {
  InputSectionBase *Sec = getRelocatedSection();

  for (const RelTy &Rel : Rels) {
    RelType Type = Rel.getType(Config->IsMips64EL);
    Symbol &Sym = getFile<ELFT>()->getRelocTargetSym(Rel);

    auto *P = reinterpret_cast<typename ELFT::Rela *>(Buf);
    Buf += sizeof(RelTy);

    if (Config->IsRela)
      P->r_addend = getAddend<ELFT>(Rel);

    // Output section VA is zero for -r, so r_offset is an offset within the
    // section, but for --emit-relocs it is an virtual address.
    P->r_offset = Sec->getOutputSection()->Addr + Sec->getOffset(Rel.r_offset);
    P->setSymbolAndType(InX::SymTab->getSymbolIndex(&Sym), Type,
                        Config->IsMips64EL);

    if (Sym.Type == STT_SECTION) {
      // We combine multiple section symbols into only one per
      // section. This means we have to update the addend. That is
      // trivial for Elf_Rela, but for Elf_Rel we have to write to the
      // section data. We do that by adding to the Relocation vector.

      // .eh_frame is horribly special and can reference discarded sections. To
      // avoid having to parse and recreate .eh_frame, we just replace any
      // relocation in it pointing to discarded sections with R_*_NONE, which
      // hopefully creates a frame that is ignored at runtime.
      auto *D = dyn_cast<Defined>(&Sym);
      if (!D) {
        error("STT_SECTION symbol should be defined");
        continue;
      }
      SectionBase *Section = D->Section;
      if (Section == &InputSection::Discarded) {
        P->setSymbolAndType(0, 0, false);
        continue;
      }

      if (Config->IsRela) {
        P->r_addend =
            Sym.getVA(getAddend<ELFT>(Rel)) - Section->getOutputSection()->Addr;
      } else if (Config->Relocatable) {
        const uint8_t *BufLoc = Sec->Data.begin() + Rel.r_offset;
        Sec->Relocations.push_back({R_ABS, Type, Rel.r_offset,
                                    Target->getImplicitAddend(BufLoc, Type),
                                    &Sym});
      }
    }

  }
}
Пример #2
0
template <class ELFT> void OutputSection::finalize() {
  if (Type == SHT_NOBITS)
    for (BaseCommand *Base : SectionCommands)
      if (isa<ByteCommand>(Base))
        Type = SHT_PROGBITS;

  std::vector<InputSection *> V = getInputSections(this);
  InputSection *First = V.empty() ? nullptr : V[0];

  if (Flags & SHF_LINK_ORDER) {
    // We must preserve the link order dependency of sections with the
    // SHF_LINK_ORDER flag. The dependency is indicated by the sh_link field. We
    // need to translate the InputSection sh_link to the OutputSection sh_link,
    // all InputSections in the OutputSection have the same dependency.
    if (auto *D = First->getLinkOrderDep())
      Link = D->getParent()->SectionIndex;
  }

  if (Type == SHT_GROUP) {
    finalizeShtGroup<ELFT>(this, First);
    return;
  }

  if (!Config->CopyRelocs || (Type != SHT_RELA && Type != SHT_REL))
    return;

  if (isa<SyntheticSection>(First))
    return;

  Link = In.SymTab->getParent()->SectionIndex;
  // sh_info for SHT_REL[A] sections should contain the section header index of
  // the section to which the relocation applies.
  InputSectionBase *S = First->getRelocatedSection();
  Info = S->getOutputSection()->SectionIndex;
  Flags |= SHF_INFO_LINK;
}