[ELF] Convert MIPS .rld_map to input section

[atanasyan]

LGTM Thanks!

[ruiu]

ELF/SyntheticSections.cpp

1663–1666 ↗

(On Diff #78839)

This should be moved to writeTo.

ELF/SyntheticSections.h

606 ↗

(On Diff #78839)

Can you derive from SyntheticSection?

613 ↗

(On Diff #78839)

You could just define typename ELFT::uint Dummy;.

But this is probably not a dummy because we actually need it. Maybe Pad?

[evgeny777]

Oops, looks like I committed it too early, but I did the required fixes

lld/trunk/ELF/OutputSections.h

 // until Writer is initialized.
 template <class ELFT> struct Out {
   typedef typename ELFT::uint uintX_t;
   typedef typename ELFT::Phdr Elf_Phdr;
 
   static uint8_t First;
   static EhOutputSection<ELFT> *EhFrame;
   static OutputSection<ELFT> *Bss;
-  static OutputSection<ELFT> *MipsRldMap;
   static OutputSectionBase *Opd;
   static uint8_t *OpdBuf;
   static Elf_Phdr *TlsPhdr;
   static OutputSectionBase *DebugInfo;
   static OutputSectionBase *ElfHeader;
   static OutputSectionBase *ProgramHeaders;
   static OutputSectionBase *PreinitArray;
   static OutputSectionBase *InitArray;
template <class ELFT> uint64_t getHeaderSize() {
   if (Config->OFormatBinary)
     return 0;
   return Out<ELFT>::ElfHeader->Size + Out<ELFT>::ProgramHeaders->Size;
 }
 
 template <class ELFT> uint8_t Out<ELFT>::First;
 template <class ELFT> EhOutputSection<ELFT> *Out<ELFT>::EhFrame;
 template <class ELFT> OutputSection<ELFT> *Out<ELFT>::Bss;
-template <class ELFT> OutputSection<ELFT> *Out<ELFT>::MipsRldMap;
 template <class ELFT> OutputSectionBase *Out<ELFT>::Opd;
 template <class ELFT> uint8_t *Out<ELFT>::OpdBuf;
 template <class ELFT> typename ELFT::Phdr *Out<ELFT>::TlsPhdr;
 template <class ELFT> OutputSectionBase *Out<ELFT>::DebugInfo;
 template <class ELFT> OutputSectionBase *Out<ELFT>::ElfHeader;
 template <class ELFT> OutputSectionBase *Out<ELFT>::ProgramHeaders;
 template <class ELFT> OutputSectionBase *Out<ELFT>::PreinitArray;
 template <class ELFT> OutputSectionBase *Out<ELFT>::InitArray;

lld/trunk/ELF/SyntheticSections.h

public:
   MipsReginfoSection(Elf_Mips_RegInfo Reginfo);
   size_t getSize() const override { return sizeof(Elf_Mips_RegInfo); }
   void writeTo(uint8_t *Buf) override;
 
 private:
   Elf_Mips_RegInfo Reginfo;
 };
 
+// This is a MIPS specific section to hold a space within the data segment
+// of executable file which is pointed to by the DT_MIPS_RLD_MAP entry.
+// See "Dynamic section" in Chapter 5 in the following document:
+// ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
+template <class ELFT> class MipsRldMap : public SyntheticSection<ELFT> {
+public:
+  MipsRldMap();
+  size_t getSize() const override { return sizeof(typename ELFT::uint); }
+  void writeTo(uint8_t *Buf) override;
+};
+
 template <class ELFT> InputSection<ELFT> *createCommonSection();
 template <class ELFT> InputSection<ELFT> *createInterpSection();
 template <class ELFT> MergeInputSection<ELFT> *createCommentSection();
 
 // Linker generated sections which can be used as inputs.
 template <class ELFT> struct In {
   static BuildIdSection<ELFT> *BuildId;
   static InputSection<ELFT> *Common;
   static DynamicSection<ELFT> *Dynamic;
   static StringTableSection<ELFT> *DynStrTab;
   static SymbolTableSection<ELFT> *DynSymTab;
   static EhFrameHeader<ELFT> *EhFrameHdr;
   static GnuHashTableSection<ELFT> *GnuHashTab;
   static GdbIndexSection<ELFT> *GdbIndex;
   static GotSection<ELFT> *Got;
   static MipsGotSection<ELFT> *MipsGot;
   static GotPltSection<ELFT> *GotPlt;
   static HashTableSection<ELFT> *HashTab;
   static InputSection<ELFT> *Interp;
+  static MipsRldMap<ELFT> *MipsRldMap;
   static PltSection<ELFT> *Plt;
   static RelocationSection<ELFT> *RelaDyn;
   static RelocationSection<ELFT> *RelaPlt;
   static StringTableSection<ELFT> *ShStrTab;
   static StringTableSection<ELFT> *StrTab;
   static SymbolTableSection<ELFT> *SymTab;
   static VersionDefinitionSection<ELFT> *VerDef;
   static VersionTableSection<ELFT> *VerSym;
   static VersionNeedSection<ELFT> *VerNeed;
 };
 
 template <class ELFT> BuildIdSection<ELFT> *In<ELFT>::BuildId;
 template <class ELFT> InputSection<ELFT> *In<ELFT>::Common;
 template <class ELFT> DynamicSection<ELFT> *In<ELFT>::Dynamic;
 template <class ELFT> StringTableSection<ELFT> *In<ELFT>::DynStrTab;
 template <class ELFT> SymbolTableSection<ELFT> *In<ELFT>::DynSymTab;
 template <class ELFT> EhFrameHeader<ELFT> *In<ELFT>::EhFrameHdr;
 template <class ELFT> GdbIndexSection<ELFT> *In<ELFT>::GdbIndex;
 template <class ELFT> GnuHashTableSection<ELFT> *In<ELFT>::GnuHashTab;
 template <class ELFT> GotSection<ELFT> *In<ELFT>::Got;
 template <class ELFT> MipsGotSection<ELFT> *In<ELFT>::MipsGot;
 template <class ELFT> GotPltSection<ELFT> *In<ELFT>::GotPlt;
 template <class ELFT> HashTableSection<ELFT> *In<ELFT>::HashTab;
 template <class ELFT> InputSection<ELFT> *In<ELFT>::Interp;
+template <class ELFT> MipsRldMap<ELFT> *In<ELFT>::MipsRldMap;
 template <class ELFT> PltSection<ELFT> *In<ELFT>::Plt;
 template <class ELFT> RelocationSection<ELFT> *In<ELFT>::RelaDyn;
 template <class ELFT> RelocationSection<ELFT> *In<ELFT>::RelaPlt;
 template <class ELFT> StringTableSection<ELFT> *In<ELFT>::ShStrTab;
 template <class ELFT> StringTableSection<ELFT> *In<ELFT>::StrTab;
 template <class ELFT> SymbolTableSection<ELFT> *In<ELFT>::SymTab;
 template <class ELFT> VersionDefinitionSection<ELFT> *In<ELFT>::VerDef;
 template <class ELFT> VersionTableSection<ELFT> *In<ELFT>::VerSym;
 template <class ELFT> VersionNeedSection<ELFT> *In<ELFT>::VerNeed;
 } // namespace elf
 } // namespace lld
 
 #endif

lld/trunk/ELF/SyntheticSections.cpp

 // input sections.
 //
 //===----------------------------------------------------------------------===//
 
 #include "SyntheticSections.h"
 #include "Config.h"
 #include "Error.h"
 #include "InputFiles.h"
+#include "LinkerScript.h"
 #include "Memory.h"
 #include "OutputSections.h"
 #include "Strings.h"
 #include "SymbolTable.h"
 #include "Target.h"
 #include "Writer.h"
 
 #include "lld/Config/Version.h"
if (Config->EMachine == EM_MIPS) {
     add({DT_MIPS_BASE_ADDRESS, Config->ImageBase});
     add({DT_MIPS_SYMTABNO, In<ELFT>::DynSymTab->getNumSymbols()});
     add({DT_MIPS_LOCAL_GOTNO, In<ELFT>::MipsGot->getLocalEntriesNum()});
     if (const SymbolBody *B = In<ELFT>::MipsGot->getFirstGlobalEntry())
       add({DT_MIPS_GOTSYM, B->DynsymIndex});
     else
       add({DT_MIPS_GOTSYM, In<ELFT>::DynSymTab->getNumSymbols()});
     add({DT_PLTGOT, In<ELFT>::MipsGot});
-    if (Out<ELFT>::MipsRldMap)
-      add({DT_MIPS_RLD_MAP, Out<ELFT>::MipsRldMap});
+    if (In<ELFT>::MipsRldMap)
+      add({DT_MIPS_RLD_MAP, In<ELFT>::MipsRldMap});
   }
 
   this->OutSec->Entsize = this->Entsize;
   this->OutSec->Link = this->Link;
 
   // +1 for DT_NULL
   this->Size = (Entries.size() + 1) * this->Entsize;
 }

 
 template <class ELFT> size_t VersionNeedSection<ELFT>::getSize() const {
   unsigned Size = Needed.size() * sizeof(Elf_Verneed);
   for (const std::pair<SharedFile<ELFT> *, size_t> &P : Needed)
     Size += P.first->VerdefMap.size() * sizeof(Elf_Vernaux);
   return Size;
 }
 
+template <class ELFT>
+MipsRldMap<ELFT>::MipsRldMap()
+    : SyntheticSection<ELFT>(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
+                             sizeof(typename ELFT::uint), ".rld_map") {}
+
+template <class ELFT> void MipsRldMap<ELFT>::writeTo(uint8_t *Buf) {
+
+  // Apply filler from linker script.
+  uint64_t Filler = Script<ELFT>::X->getFiller(this->Name);
+  Filler = (Filler << 32) | Filler;
+  memcpy(Buf, &Filler, getSize());
+}
+
 template InputSection<ELF32LE> *elf::createCommonSection();
 template InputSection<ELF32BE> *elf::createCommonSection();
 template InputSection<ELF64LE> *elf::createCommonSection();
 template InputSection<ELF64BE> *elf::createCommonSection();
 
 template InputSection<ELF32LE> *elf::createInterpSection();
 template InputSection<ELF32BE> *elf::createInterpSection();
 template InputSection<ELF64LE> *elf::createInterpSection();

 template class elf::VersionNeedSection<ELF32BE>;
 template class elf::VersionNeedSection<ELF64LE>;
 template class elf::VersionNeedSection<ELF64BE>;
 
 template class elf::VersionDefinitionSection<ELF32LE>;
 template class elf::VersionDefinitionSection<ELF32BE>;
 template class elf::VersionDefinitionSection<ELF64LE>;
 template class elf::VersionDefinitionSection<ELF64BE>;
+
+template class elf::MipsRldMap<ELF32LE>;
+template class elf::MipsRldMap<ELF32BE>;
+template class elf::MipsRldMap<ELF64LE>;
+template class elf::MipsRldMap<ELF64BE>;

lld/trunk/ELF/Writer.cpp

template <class ELFT> void Writer<ELFT>::createSyntheticSections() {
 
   In<ELFT>::RelaPlt = make<RelocationSection<ELFT>>(
       Config->Rela ? ".rela.plt" : ".rel.plt", false /*Sort*/);
   if (Config->Strip != StripPolicy::All) {
     In<ELFT>::StrTab = make<StringTableSection<ELFT>>(".strtab", false);
     In<ELFT>::SymTab = make<SymbolTableSection<ELFT>>(*In<ELFT>::StrTab);
   }
 
-  if (Config->EMachine == EM_MIPS && !Config->Shared) {
-    // This is a MIPS specific section to hold a space within the data segment
-    // of executable file which is pointed to by the DT_MIPS_RLD_MAP entry.
-    // See "Dynamic section" in Chapter 5 in the following document:
-    // ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
-    Out<ELFT>::MipsRldMap = make<OutputSection<ELFT>>(".rld_map", SHT_PROGBITS,
-                                                      SHF_ALLOC | SHF_WRITE);
-    Out<ELFT>::MipsRldMap->Size = sizeof(uintX_t);
-    Out<ELFT>::MipsRldMap->updateAlignment(sizeof(uintX_t));
-  }
   if (!Config->VersionDefinitions.empty())
     In<ELFT>::VerDef = make<VersionDefinitionSection<ELFT>>();
 
   // Initialize linker generated sections
   if (!Config->Relocatable)
     Symtab<ELFT>::X->Sections.push_back(createCommentSection<ELFT>());
 
   if (Config->BuildId != BuildIdKind::None) {
     In<ELFT>::BuildId = make<BuildIdSection<ELFT>>();
     Symtab<ELFT>::X->Sections.push_back(In<ELFT>::BuildId);
   }
 
   InputSection<ELFT> *Common = createCommonSection<ELFT>();
   if (!Common->Data.empty()) {
     In<ELFT>::Common = Common;
     Symtab<ELFT>::X->Sections.push_back(Common);
   }
 
   // Add MIPS-specific sections.
   if (Config->EMachine == EM_MIPS) {
+    if (!Config->Shared && In<ELFT>::DynSymTab) {
+      In<ELFT>::MipsRldMap = make<MipsRldMap<ELFT>>();
+      Symtab<ELFT>::X->Sections.push_back(In<ELFT>::MipsRldMap);
+    }
     if (auto *Sec = MipsAbiFlagsSection<ELFT>::create())
       Symtab<ELFT>::X->Sections.push_back(Sec);
     if (auto *Sec = MipsOptionsSection<ELFT>::create())
       Symtab<ELFT>::X->Sections.push_back(Sec);
     if (auto *Sec = MipsReginfoSection<ELFT>::create())
       Symtab<ELFT>::X->Sections.push_back(Sec);
   }
 
if (HasVerNeed)
       addInputSec(In<ELFT>::VerNeed);
 
     addInputSec(In<ELFT>::GnuHashTab);
     addInputSec(In<ELFT>::HashTab);
     addInputSec(In<ELFT>::Dynamic);
     addInputSec(In<ELFT>::DynStrTab);
     if (In<ELFT>::RelaDyn->hasRelocs())
       addInputSec(In<ELFT>::RelaDyn);
-    Add(Out<ELFT>::MipsRldMap);
   }
 
   // We always need to add rel[a].plt to output if it has entries.
   // Even during static linking it can contain R_[*]_IRELATIVE relocations.
   if (In<ELFT>::RelaPlt->hasRelocs())
     addInputSec(In<ELFT>::RelaPlt);
 
   // We fill .got and .got.plt sections in scanRelocs(). This is the