Convert Out::InterpSection to In::InterpSection.

Differential Revision: https://reviews.llvm.org/D26225

llvm-svn: 285851

lld/ELF/OutputSections.cpp

@@ -496,17 +496,6 @@ template <class ELFT> void RelocationSection<ELFT>::finalize() {
   this->Header.sh_size = Relocs.size() * this->Header.sh_entsize;
 }
 
-template <class ELFT>
-InterpSection<ELFT>::InterpSection()
-    : OutputSectionBase<ELFT>(".interp", SHT_PROGBITS, SHF_ALLOC) {
-  this->Header.sh_size = Config->DynamicLinker.size() + 1;
-}
-
-template <class ELFT> void InterpSection<ELFT>::writeTo(uint8_t *Buf) {
-  StringRef S = Config->DynamicLinker;
-  memcpy(Buf, S.data(), S.size());
-}
-
 template <class ELFT>
 HashTableSection<ELFT>::HashTableSection()
     : OutputSectionBase<ELFT>(".hash", SHT_HASH, SHF_ALLOC) {
@@ -1969,11 +1958,6 @@ template class RelocationSection<ELF32BE>;
 template class RelocationSection<ELF64LE>;
 template class RelocationSection<ELF64BE>;
 
-template class InterpSection<ELF32LE>;
-template class InterpSection<ELF32BE>;
-template class InterpSection<ELF64LE>;
-template class InterpSection<ELF64BE>;
-
 template class GnuHashTableSection<ELF32LE>;
 template class GnuHashTableSection<ELF32BE>;
 template class GnuHashTableSection<ELF64LE>;

lld/ELF/OutputSections.h

@@ -56,7 +56,6 @@ public:
     Got,
     GotPlt,
     HashTable,
-    Interp,
     Merge,
     MipsReginfo,
     MipsOptions,
@@ -516,17 +515,6 @@ private:
   llvm::DenseMap<std::pair<ArrayRef<uint8_t>, SymbolBody *>, CieRecord> CieMap;
 };
 
-template <class ELFT>
-class InterpSection final : public OutputSectionBase<ELFT> {
-  typedef OutputSectionBase<ELFT> Base;
-
-public:
-  InterpSection();
-  void writeTo(uint8_t *Buf) override;
-  typename Base::Kind getKind() const override { return Base::Interp; }
-  static bool classof(const Base *B) { return B->getKind() == Base::Interp; }
-};
-
 template <class ELFT>
 class StringTableSection final : public OutputSectionBase<ELFT> {
   typedef OutputSectionBase<ELFT> Base;
@@ -755,7 +743,6 @@ template <class ELFT> struct Out {
   static GotPltSection<ELFT> *GotPlt;
   static GotSection<ELFT> *Got;
   static HashTableSection<ELFT> *HashTab;
-  static InterpSection<ELFT> *Interp;
   static OutputSection<ELFT> *Bss;
   static OutputSection<ELFT> *MipsRldMap;
   static OutputSectionBase<ELFT> *Opd;
@@ -822,7 +809,6 @@ template <class ELFT> GnuHashTableSection<ELFT> *Out<ELFT>::GnuHashTab;
 template <class ELFT> GotPltSection<ELFT> *Out<ELFT>::GotPlt;
 template <class ELFT> GotSection<ELFT> *Out<ELFT>::Got;
 template <class ELFT> HashTableSection<ELFT> *Out<ELFT>::HashTab;
-template <class ELFT> InterpSection<ELFT> *Out<ELFT>::Interp;
 template <class ELFT> OutputSection<ELFT> *Out<ELFT>::Bss;
 template <class ELFT> OutputSection<ELFT> *Out<ELFT>::MipsRldMap;
 template <class ELFT> OutputSectionBase<ELFT> *Out<ELFT>::Opd;

lld/ELF/SyntheticSections.cpp

@@ -18,6 +18,7 @@
 #include "Config.h"
 #include "Error.h"
 #include "InputFiles.h"
+#include "Memory.h"
 #include "OutputSections.h"
 #include "Strings.h"
 
@@ -36,6 +37,17 @@ using namespace llvm::support::endian;
 using namespace lld;
 using namespace lld::elf;
 
+static ArrayRef<uint8_t> createInterp() {
+  // StringSaver guarantees that the returned string ends with '\0'.
+  StringRef S = Saver.save(Config->DynamicLinker);
+  return {(uint8_t *)S.data(), S.size() + 1};
+}
+
+template <class ELFT>
+InterpSection<ELFT>::InterpSection()
+    : InputSection<ELFT>(SHF_ALLOC, SHT_PROGBITS, 1, createInterp(),
+                         ".interp") {}
+
 template <class ELFT>
 BuildIdSection<ELFT>::BuildIdSection(size_t HashSize)
     : InputSection<ELFT>(SHF_ALLOC, SHT_NOTE, 1, ArrayRef<uint8_t>(),
@@ -95,6 +107,11 @@ void BuildIdHexstring<ELFT>::writeBuildId(MutableArrayRef<uint8_t> Buf) {
          Config->BuildIdVector.size());
 }
 
+template class elf::InterpSection<ELF32LE>;
+template class elf::InterpSection<ELF32BE>;
+template class elf::InterpSection<ELF64LE>;
+template class elf::InterpSection<ELF64BE>;
+
 template class elf::BuildIdSection<ELF32LE>;
 template class elf::BuildIdSection<ELF32BE>;
 template class elf::BuildIdSection<ELF64LE>;

lld/ELF/SyntheticSections.h

@@ -15,6 +15,11 @@
 namespace lld {
 namespace elf {
 
+template <class ELFT> class InterpSection final : public InputSection<ELFT> {
+public:
+  InterpSection();
+};
+
 template <class ELFT> class BuildIdSection : public InputSection<ELFT> {
 public:
   virtual void writeBuildId(llvm::MutableArrayRef<uint8_t> Buf) = 0;
@@ -62,10 +67,12 @@ public:
 // Linker generated sections which can be used as inputs.
 template <class ELFT> struct In {
   static BuildIdSection<ELFT> *BuildId;
+  static InterpSection<ELFT> *Interp;
   static std::vector<InputSection<ELFT> *> Sections;
 };
 
 template <class ELFT> BuildIdSection<ELFT> *In<ELFT>::BuildId;
+template <class ELFT> InterpSection<ELFT> *In<ELFT>::Interp;
 template <class ELFT> std::vector<InputSection<ELFT> *> In<ELFT>::Sections;
 
 } // namespace elf

lld/ELF/Writer.cpp

@@ -235,7 +235,7 @@ template <class ELFT> void Writer<ELFT>::createSyntheticSections() {
   Out<ELFT>::ProgramHeaders->updateAlignment(sizeof(uintX_t));
 
   if (needsInterpSection<ELFT>())
-    Out<ELFT>::Interp = make<InterpSection<ELFT>>();
+    In<ELFT>::Interp = make<InterpSection<ELFT>>();
 
   if (!Symtab<ELFT>::X->getSharedFiles().empty() || Config->Pic) {
     Out<ELFT>::DynSymTab =
@@ -284,7 +284,8 @@ template <class ELFT> void Writer<ELFT>::createSyntheticSections() {
     In<ELFT>::BuildId = make<BuildIdUuid<ELFT>>();
   else if (Config->BuildId == BuildIdKind::Hexstring)
     In<ELFT>::BuildId = make<BuildIdHexstring<ELFT>>();
-  In<ELFT>::Sections = {In<ELFT>::BuildId};
+
+  In<ELFT>::Sections = {In<ELFT>::BuildId, In<ELFT>::Interp};
 }
 
 template <class ELFT>
@@ -408,6 +409,13 @@ template <class ELFT> bool elf::isRelroSection(OutputSectionBase<ELFT> *Sec) {
 template <class ELFT>
 static bool compareSectionsNonScript(OutputSectionBase<ELFT> *A,
                                      OutputSectionBase<ELFT> *B) {
+  // Put .interp first because some loaders want to see that section
+  // on the first page of the executable file when loaded into memory.
+  bool AIsInterp = A->getName() == ".interp";
+  bool BIsInterp = B->getName() == ".interp";
+  if (AIsInterp != BIsInterp)
+    return AIsInterp;
+
   typedef typename ELFT::uint uintX_t;
   uintX_t AFlags = A->getFlags();
   uintX_t BFlags = B->getFlags();
@@ -872,11 +880,6 @@ template <class ELFT> void Writer<ELFT>::addPredefinedSections() {
       OutputSections.push_back(OS);
   };
 
-  // Add .interp at first because some loaders want to see that section
-  // on the first page of the executable file when loaded into memory.
-  if (Out<ELFT>::Interp)
-    OutputSections.insert(OutputSections.begin(), Out<ELFT>::Interp);
-
   // This order is not the same as the final output order
   // because we sort the sections using their attributes below.
   if (Out<ELFT>::GdbIndex && Out<ELFT>::DebugInfo)
@@ -999,9 +1002,9 @@ template <class ELFT> std::vector<PhdrEntry<ELFT>> Writer<ELFT>::createPhdrs() {
   Hdr.add(Out<ELFT>::ProgramHeaders);
 
   // PT_INTERP must be the second entry if exists.
-  if (Out<ELFT>::Interp) {
-    Phdr &Hdr = *AddHdr(PT_INTERP, Out<ELFT>::Interp->getPhdrFlags());
-    Hdr.add(Out<ELFT>::Interp);
+  if (OutputSectionBase<ELFT> *Sec = findSection(".interp")) {
+    Phdr &Hdr = *AddHdr(PT_INTERP, Sec->getPhdrFlags());
+    Hdr.add(Sec);
   }
 
   // Add the first PT_LOAD segment for regular output sections.