[llvm] 7570d38 - [yaml2obj/obj2yaml] - Add support for SHT_RELR sections.

Georgii Rymar via llvm-commits llvm-commits at lists.llvm.org
Wed Jan 15 04:15:47 PST 2020


Author: Georgii Rymar
Date: 2020-01-15T15:15:24+03:00
New Revision: 7570d387c21935b58afa67cb9ee17250e38721fa

URL: https://github.com/llvm/llvm-project/commit/7570d387c21935b58afa67cb9ee17250e38721fa
DIFF: https://github.com/llvm/llvm-project/commit/7570d387c21935b58afa67cb9ee17250e38721fa.diff

LOG: [yaml2obj/obj2yaml] - Add support for SHT_RELR sections.

Note: this is a reland with a trivial 2 lines fix in ELFState<ELFT>::writeSectionContent.
      It adds a check similar to ones we already have for other sections to fix the case revealed
      by bots, like http://lab.llvm.org:8011/builders/llvm-clang-lld-x86_64-scei-ps4-ubuntu-fast/builds/60744.

The encoded sequence of Elf*_Relr entries in a SHT_RELR section looks
like [ AAAAAAAA BBBBBBB1 BBBBBBB1 ... AAAAAAAA BBBBBB1 ... ]
i.e. start with an address, followed by any number of bitmaps. The address
entry encodes 1 relocation. The subsequent bitmap entries encode up to 63(31)
relocations each, at subsequent offsets following the last address entry.

More information is here:
https://github.com/llvm-mirror/llvm/blob/master/lib/Object/ELF.cpp#L272

This patch adds a support for these sections.

Differential revision: https://reviews.llvm.org/D71872

Added: 
    

Modified: 
    llvm/include/llvm/ObjectYAML/ELFYAML.h
    llvm/lib/ObjectYAML/ELFEmitter.cpp
    llvm/lib/ObjectYAML/ELFYAML.cpp
    llvm/tools/obj2yaml/elf2yaml.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/ObjectYAML/ELFYAML.h b/llvm/include/llvm/ObjectYAML/ELFYAML.h
index c9f14589906f..f87135e6a1b5 100644
--- a/llvm/include/llvm/ObjectYAML/ELFYAML.h
+++ b/llvm/include/llvm/ObjectYAML/ELFYAML.h
@@ -138,6 +138,7 @@ struct Chunk {
     Group,
     RawContent,
     Relocation,
+    Relr,
     NoBits,
     Note,
     Hash,
@@ -440,6 +441,17 @@ struct RelocationSection : Section {
   }
 };
 
+struct RelrSection : Section {
+  Optional<std::vector<llvm::yaml::Hex64>> Entries;
+  Optional<yaml::BinaryRef> Content;
+
+  RelrSection() : Section(ChunkKind::Relr) {}
+
+  static bool classof(const Chunk *S) {
+    return S->Kind == ChunkKind::Relr;
+  }
+};
+
 struct SymtabShndxSection : Section {
   std::vector<uint32_t> Entries;
 

diff  --git a/llvm/lib/ObjectYAML/ELFEmitter.cpp b/llvm/lib/ObjectYAML/ELFEmitter.cpp
index 69f5510fc7fa..ee7d5f616a73 100644
--- a/llvm/lib/ObjectYAML/ELFEmitter.cpp
+++ b/llvm/lib/ObjectYAML/ELFEmitter.cpp
@@ -110,6 +110,7 @@ template <class ELFT> class ELFState {
   typedef typename ELFT::Rela Elf_Rela;
   typedef typename ELFT::Relr Elf_Relr;
   typedef typename ELFT::Dyn Elf_Dyn;
+  typedef typename ELFT::uint uintX_t;
 
   enum class SymtabType { Static, Dynamic };
 
@@ -165,6 +166,9 @@ template <class ELFT> class ELFState {
   void writeSectionContent(Elf_Shdr &SHeader,
                            const ELFYAML::RelocationSection &Section,
                            ContiguousBlobAccumulator &CBA);
+  void writeSectionContent(Elf_Shdr &SHeader,
+                           const ELFYAML::RelrSection &Section,
+                           ContiguousBlobAccumulator &CBA);
   void writeSectionContent(Elf_Shdr &SHeader, const ELFYAML::Group &Group,
                            ContiguousBlobAccumulator &CBA);
   void writeSectionContent(Elf_Shdr &SHeader,
@@ -454,6 +458,8 @@ void ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
       writeSectionContent(SHeader, *S, CBA);
     } else if (auto S = dyn_cast<ELFYAML::RelocationSection>(Sec)) {
       writeSectionContent(SHeader, *S, CBA);
+    } else if (auto S = dyn_cast<ELFYAML::RelrSection>(Sec)) {
+      writeSectionContent(SHeader, *S, CBA);
     } else if (auto S = dyn_cast<ELFYAML::Group>(Sec)) {
       writeSectionContent(SHeader, *S, CBA);
     } else if (auto S = dyn_cast<ELFYAML::MipsABIFlags>(Sec)) {
@@ -770,10 +776,6 @@ void ELFState<ELFT>::writeSectionContent(
 
   if (Section.EntSize)
     SHeader.sh_entsize = *Section.EntSize;
-  else if (Section.Type == llvm::ELF::SHT_RELR)
-    SHeader.sh_entsize = sizeof(Elf_Relr);
-  else
-    SHeader.sh_entsize = 0;
 
   if (Section.Info)
     SHeader.sh_info = *Section.Info;
@@ -827,6 +829,33 @@ void ELFState<ELFT>::writeSectionContent(
   }
 }
 
+template <class ELFT>
+void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
+                                         const ELFYAML::RelrSection &Section,
+                                         ContiguousBlobAccumulator &CBA) {
+  raw_ostream &OS =
+      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
+  SHeader.sh_entsize =
+      Section.EntSize ? uint64_t(*Section.EntSize) : sizeof(Elf_Relr);
+
+  if (Section.Content) {
+    SHeader.sh_size = writeContent(OS, Section.Content, None);
+    return;
+  }
+
+  if (!Section.Entries)
+    return;
+
+  for (llvm::yaml::Hex64 E : *Section.Entries) {
+    if (!ELFT::Is64Bits && E > UINT32_MAX)
+      reportError(Section.Name + ": the value is too large for 32-bits: 0x" +
+                  Twine::utohexstr(E));
+    support::endian::write<uintX_t>(OS, E, ELFT::TargetEndianness);
+  }
+
+  SHeader.sh_size = sizeof(uintX_t) * Section.Entries->size();
+}
+
 template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(
     Elf_Shdr &SHeader, const ELFYAML::SymtabShndxSection &Shndx,
@@ -889,7 +918,6 @@ template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(
     Elf_Shdr &SHeader, const ELFYAML::StackSizesSection &Section,
     ContiguousBlobAccumulator &CBA) {
-  using uintX_t = typename ELFT::uint;
   raw_ostream &OS =
       CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 
@@ -1115,8 +1143,6 @@ template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
                                          const ELFYAML::DynamicSection &Section,
                                          ContiguousBlobAccumulator &CBA) {
-  typedef typename ELFT::uint uintX_t;
-
   assert(Section.Type == llvm::ELF::SHT_DYNAMIC &&
          "Section type is not SHT_DYNAMIC");
 

diff  --git a/llvm/lib/ObjectYAML/ELFYAML.cpp b/llvm/lib/ObjectYAML/ELFYAML.cpp
index 21ae85022c25..efa7ecb4728b 100644
--- a/llvm/lib/ObjectYAML/ELFYAML.cpp
+++ b/llvm/lib/ObjectYAML/ELFYAML.cpp
@@ -1101,6 +1101,12 @@ static void sectionMapping(IO &IO, ELFYAML::RelocationSection &Section) {
   IO.mapOptional("Relocations", Section.Relocations);
 }
 
+static void sectionMapping(IO &IO, ELFYAML::RelrSection &Section) {
+  commonSectionMapping(IO, Section);
+  IO.mapOptional("Entries", Section.Entries);
+  IO.mapOptional("Content", Section.Content);
+}
+
 static void groupSectionMapping(IO &IO, ELFYAML::Group &Group) {
   commonSectionMapping(IO, Group);
   IO.mapOptional("Info", Group.Signature);
@@ -1200,6 +1206,11 @@ void MappingTraits<std::unique_ptr<ELFYAML::Chunk>>::mapping(
       Section.reset(new ELFYAML::RelocationSection());
     sectionMapping(IO, *cast<ELFYAML::RelocationSection>(Section.get()));
     break;
+  case ELF::SHT_RELR:
+    if (!IO.outputting())
+      Section.reset(new ELFYAML::RelrSection());
+    sectionMapping(IO, *cast<ELFYAML::RelrSection>(Section.get()));
+    break;
   case ELF::SHT_GROUP:
     if (!IO.outputting())
       Section.reset(new ELFYAML::Group());
@@ -1441,6 +1452,12 @@ StringRef MappingTraits<std::unique_ptr<ELFYAML::Chunk>>::validate(
     return {};
   }
 
+  if (const auto *RS = dyn_cast<ELFYAML::RelrSection>(C.get())) {
+    if (RS->Entries && RS->Content)
+      return "\"Entries\" and \"Content\" can't be used together";
+    return {};
+  }
+
   return {};
 }
 

diff  --git a/llvm/tools/obj2yaml/elf2yaml.cpp b/llvm/tools/obj2yaml/elf2yaml.cpp
index 75d2e427b4f2..904d1ad9d0ae 100644
--- a/llvm/tools/obj2yaml/elf2yaml.cpp
+++ b/llvm/tools/obj2yaml/elf2yaml.cpp
@@ -27,6 +27,7 @@ class ELFDumper {
   typedef typename ELFT::Word Elf_Word;
   typedef typename ELFT::Rel Elf_Rel;
   typedef typename ELFT::Rela Elf_Rela;
+  using Elf_Relr = typename ELFT::Relr;
   using Elf_Nhdr = typename ELFT::Nhdr;
   using Elf_Note = typename ELFT::Note;
 
@@ -66,6 +67,7 @@ class ELFDumper {
   dumpDependentLibrariesSection(const Elf_Shdr *Shdr);
   Expected<ELFYAML::DynamicSection *> dumpDynamicSection(const Elf_Shdr *Shdr);
   Expected<ELFYAML::RelocationSection *> dumpRelocSection(const Elf_Shdr *Shdr);
+  Expected<ELFYAML::RelrSection *> dumpRelrSection(const Elf_Shdr *Shdr);
   Expected<ELFYAML::RawContentSection *>
   dumpContentSection(const Elf_Shdr *Shdr);
   Expected<ELFYAML::SymtabShndxSection *>
@@ -251,6 +253,13 @@ template <class ELFT> Expected<ELFYAML::Object *> ELFDumper<ELFT>::dump() {
       Y->Chunks.emplace_back(*SecOrErr);
       break;
     }
+    case ELF::SHT_RELR: {
+      Expected<ELFYAML::RelrSection *> SecOrErr = dumpRelrSection(&Sec);
+      if (!SecOrErr)
+        return SecOrErr.takeError();
+      Y->Chunks.emplace_back(*SecOrErr);
+      break;
+    }
     case ELF::SHT_GROUP: {
       Expected<ELFYAML::Group *> GroupOrErr = dumpGroup(&Sec);
       if (!GroupOrErr)
@@ -723,6 +732,30 @@ ELFDumper<ELFT>::dumpRelocSection(const Elf_Shdr *Shdr) {
   return S.release();
 }
 
+template <class ELFT>
+Expected<ELFYAML::RelrSection *>
+ELFDumper<ELFT>::dumpRelrSection(const Elf_Shdr *Shdr) {
+  auto S = std::make_unique<ELFYAML::RelrSection>();
+  if (auto E = dumpCommonSection(Shdr, *S))
+    return std::move(E);
+
+  if (Expected<ArrayRef<Elf_Relr>> Relrs = Obj.relrs(Shdr)) {
+    S->Entries.emplace();
+    for (Elf_Relr Rel : *Relrs)
+      S->Entries->emplace_back(Rel);
+    return S.release();
+  } else {
+    // Ignore. We are going to dump the data as raw content below.
+    consumeError(Relrs.takeError());
+  }
+
+  Expected<ArrayRef<uint8_t>> ContentOrErr = Obj.getSectionContents(Shdr);
+  if (!ContentOrErr)
+    return ContentOrErr.takeError();
+  S->Content = *ContentOrErr;
+  return S.release();
+}
+
 template <class ELFT>
 Expected<ELFYAML::RawContentSection *>
 ELFDumper<ELFT>::dumpContentSection(const Elf_Shdr *Shdr) {


        


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