ELF: Create .gnu.version and .gnu.version_r sections when linking against versioned DSOs.
Differential Revision: http://reviews.llvm.org/D19464
llvm-svn: 267775
diff --git a/lld/ELF/OutputSections.cpp b/lld/ELF/OutputSections.cpp
index 15ddd9d..0088274 100644
--- a/lld/ELF/OutputSections.cpp
+++ b/lld/ELF/OutputSections.cpp
@@ -654,6 +654,12 @@
if (!Config->Entry.empty())
Add({DT_DEBUG, (uint64_t)0});
+ if (size_t NeedNum = Out<ELFT>::VerNeed->getNeedNum()) {
+ Add({DT_VERSYM, Out<ELFT>::VerSym});
+ Add({DT_VERNEED, Out<ELFT>::VerNeed});
+ Add({DT_VERNEEDNUM, NeedNum});
+ }
+
if (Config->EMachine == EM_MIPS) {
Add({DT_MIPS_RLD_VERSION, 1});
Add({DT_MIPS_FLAGS, RHF_NOTPOT});
@@ -1514,6 +1520,102 @@
}
template <class ELFT>
+VersionTableSection<ELFT>::VersionTableSection()
+ : OutputSectionBase<ELFT>(".gnu.version", SHT_GNU_versym, SHF_ALLOC) {}
+
+template <class ELFT> void VersionTableSection<ELFT>::finalize() {
+ this->Header.sh_size =
+ sizeof(Elf_Versym) * (Out<ELFT>::DynSymTab->getSymbols().size() + 1);
+ this->Header.sh_entsize = sizeof(Elf_Versym);
+}
+
+template <class ELFT> void VersionTableSection<ELFT>::writeTo(uint8_t *Buf) {
+ auto *OutVersym = reinterpret_cast<Elf_Versym *>(Buf) + 1;
+ for (const std::pair<SymbolBody *, size_t> &P :
+ Out<ELFT>::DynSymTab->getSymbols()) {
+ if (auto *SS = dyn_cast<SharedSymbol<ELFT>>(P.first))
+ OutVersym->vs_index = SS->VersionId;
+ else
+ // The reserved identifier for a non-versioned global symbol.
+ OutVersym->vs_index = 1;
+ ++OutVersym;
+ }
+}
+
+template <class ELFT>
+VersionNeedSection<ELFT>::VersionNeedSection()
+ : OutputSectionBase<ELFT>(".gnu.version_r", SHT_GNU_verneed, SHF_ALLOC) {}
+
+template <class ELFT>
+void VersionNeedSection<ELFT>::addSymbol(SharedSymbol<ELFT> *SS) {
+ if (!SS->Verdef) {
+ // The reserved identifier for a non-versioned global symbol.
+ SS->VersionId = 1;
+ return;
+ }
+ SharedFile<ELFT> *F = SS->File;
+ // If we don't already know that we need an Elf_Verneed for this DSO, prepare
+ // to create one by adding it to our needed list and creating a dynstr entry
+ // for the soname.
+ if (F->VerdefMap.empty())
+ Needed.push_back({F, Out<ELFT>::DynStrTab->addString(F->getSoName())});
+ typename SharedFile<ELFT>::NeededVer &NV = F->VerdefMap[SS->Verdef];
+ // If we don't already know that we need an Elf_Vernaux for this Elf_Verdef,
+ // prepare to create one by allocating a version identifier and creating a
+ // dynstr entry for the version name.
+ if (NV.Index == 0) {
+ NV.StrTab = Out<ELFT>::DynStrTab->addString(
+ SS->File->getStringTable().data() + SS->Verdef->getAux()->vda_name);
+ NV.Index = NextIndex++;
+ }
+ SS->VersionId = NV.Index;
+}
+
+template <class ELFT> void VersionNeedSection<ELFT>::writeTo(uint8_t *Buf) {
+ // The Elf_Verneeds need to appear first, followed by the Elf_Vernauxs.
+ auto *Verneed = reinterpret_cast<Elf_Verneed *>(Buf);
+ auto *Vernaux = reinterpret_cast<Elf_Vernaux *>(Verneed + Needed.size());
+
+ for (std::pair<SharedFile<ELFT> *, size_t> &P : Needed) {
+ // Create an Elf_Verneed for this DSO.
+ Verneed->vn_version = 1;
+ Verneed->vn_cnt = P.first->VerdefMap.size();
+ Verneed->vn_file = P.second;
+ Verneed->vn_aux =
+ reinterpret_cast<char *>(Vernaux) - reinterpret_cast<char *>(Verneed);
+ Verneed->vn_next = sizeof(Elf_Verneed);
+ ++Verneed;
+
+ // Create the Elf_Vernauxs for this Elf_Verneed. The loop iterates over
+ // VerdefMap, which will only contain references to needed version
+ // definitions. Each Elf_Vernaux is based on the information contained in
+ // the Elf_Verdef in the source DSO. This loop iterates over a std::map of
+ // pointers, but is deterministic because the pointers refer to Elf_Verdef
+ // data structures within a single input file.
+ for (auto &NV : P.first->VerdefMap) {
+ Vernaux->vna_hash = NV.first->vd_hash;
+ Vernaux->vna_flags = 0;
+ Vernaux->vna_other = NV.second.Index;
+ Vernaux->vna_name = NV.second.StrTab;
+ Vernaux->vna_next = sizeof(Elf_Vernaux);
+ ++Vernaux;
+ }
+
+ Vernaux[-1].vna_next = 0;
+ }
+ Verneed[-1].vn_next = 0;
+}
+
+template <class ELFT> void VersionNeedSection<ELFT>::finalize() {
+ this->Header.sh_link = Out<ELFT>::DynStrTab->SectionIndex;
+ this->Header.sh_info = Needed.size();
+ unsigned Size = Needed.size() * sizeof(Elf_Verneed);
+ for (std::pair<SharedFile<ELFT> *, size_t> &P : Needed)
+ Size += P.first->VerdefMap.size() * sizeof(Elf_Vernaux);
+ this->Header.sh_size = Size;
+}
+
+template <class ELFT>
BuildIdSection<ELFT>::BuildIdSection(size_t HashSize)
: OutputSectionBase<ELFT>(".note.gnu.build-id", SHT_NOTE, SHF_ALLOC),
HashSize(HashSize) {
@@ -1666,6 +1768,16 @@
template class SymbolTableSection<ELF64LE>;
template class SymbolTableSection<ELF64BE>;
+template class VersionTableSection<ELF32LE>;
+template class VersionTableSection<ELF32BE>;
+template class VersionTableSection<ELF64LE>;
+template class VersionTableSection<ELF64BE>;
+
+template class VersionNeedSection<ELF32LE>;
+template class VersionNeedSection<ELF32BE>;
+template class VersionNeedSection<ELF64LE>;
+template class VersionNeedSection<ELF64BE>;
+
template class BuildIdSection<ELF32LE>;
template class BuildIdSection<ELF32BE>;
template class BuildIdSection<ELF64LE>;