3 files changed, 94 insertions, 2 deletions

diff --git a/llvm/tools/llvm-objdump/ELFDump.cpp b/llvm/tools/llvm-objdump/ELFDump.cpp
index 9475ab35f11..f4d36656a6c 100644
--- a/llvm/tools/llvm-objdump/ELFDump.cpp
+++ b/llvm/tools/llvm-objdump/ELFDump.cpp
@@ -21,6 +21,77 @@
 using namespace llvm;
 using namespace llvm::object;
 
+template <class ELFT>
+Expected<StringRef> getDynamicStrTab(const ELFFile<ELFT> *Elf) {
+  typedef ELFFile<ELFT> ELFO;
+
+  auto DynamicEntriesOrError = Elf->dynamicEntries();
+  if (!DynamicEntriesOrError)
+    return DynamicEntriesOrError.takeError();
+
+  for (const typename ELFO::Elf_Dyn &Dyn : *DynamicEntriesOrError) {
+    if (Dyn.d_tag == ELF::DT_STRTAB) {
+      auto MappedAddrOrError = Elf->toMappedAddr(Dyn.getPtr());
+      if (!MappedAddrOrError)
+        consumeError(MappedAddrOrError.takeError());
+      return StringRef(reinterpret_cast<const char *>(*MappedAddrOrError));
+    }
+  }
+
+  // If the dynamic segment is not present, we fall back on the sections.
+  auto SectionsOrError = Elf->sections();
+  if (!SectionsOrError)
+    return SectionsOrError.takeError();
+
+  for (const typename ELFO::Elf_Shdr &Sec : *SectionsOrError) {
+    if (Sec.sh_type == ELF::SHT_DYNSYM)
+      return Elf->getStringTableForSymtab(Sec);
+  }
+
+  return createError("dynamic string table not found");
+}
+
+template <class ELFT>
+void printDynamicSection(const ELFFile<ELFT> *Elf, StringRef Filename) {
+  auto ProgramHeaderOrError = Elf->program_headers();
+  if (!ProgramHeaderOrError)
+    report_error(Filename, ProgramHeaderOrError.takeError());
+
+  auto DynamicEntriesOrError = Elf->dynamicEntries();
+  if (!DynamicEntriesOrError)
+    report_error(Filename, DynamicEntriesOrError.takeError());
+
+  outs() << "Dynamic Section:\n";
+  for (const auto &Dyn : *DynamicEntriesOrError) {
+    if (Dyn.d_tag == ELF::DT_NULL)
+      continue;
+
+    StringRef Str = StringRef(Elf->getDynamicTagAsString(Dyn.d_tag));
+
+    if (Str.empty()) {
+      std::string HexStr = utohexstr(static_cast<uint64_t>(Dyn.d_tag), true);
+      outs() << format("  0x%-19s", HexStr.c_str());
+    } else {
+      // We use "-21" in order to match GNU objdump's output.
+      outs() << format("  %-21s", Str.data());
+    }
+
+    const char *Fmt =
+        ELFT::Is64Bits ? "0x%016" PRIx64 "\n" : "0x%08" PRIx64 "\n";
+    if (Dyn.d_tag == ELF::DT_NEEDED) {
+      Expected<StringRef> StrTabOrErr = getDynamicStrTab(Elf);
+      if (StrTabOrErr) {
+        const char *Data = StrTabOrErr.get().data();
+        outs() << (Data + Dyn.d_un.d_val) << "\n";
+        continue;
+      }
+      warn(errorToErrorCode(StrTabOrErr.takeError()).message());
+      consumeError(StrTabOrErr.takeError());
+    }
+    outs() << format(Fmt, (uint64_t)Dyn.d_un.d_val);
+  }
+}
+
 template <class ELFT> void printProgramHeaders(const ELFFile<ELFT> *o) {
   typedef ELFFile<ELFT> ELFO;
   outs() << "Program Header:\n";
@@ -103,3 +174,21 @@ void llvm::printELFFileHeader(const object::ObjectFile *Obj) {
   if (const ELF64BEObjectFile *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj))
     printProgramHeaders(ELFObj->getELFFile());
 }
+
+void llvm::printELFDynamicSection(const object::ObjectFile *Obj) {
+  // Little-endian 32-bit
+  if (const ELF32LEObjectFile *ELFObj = dyn_cast<ELF32LEObjectFile>(Obj))
+    printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
+
+  // Big-endian 32-bit
+  if (const ELF32BEObjectFile *ELFObj = dyn_cast<ELF32BEObjectFile>(Obj))
+    printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
+
+  // Little-endian 64-bit
+  if (const ELF64LEObjectFile *ELFObj = dyn_cast<ELF64LEObjectFile>(Obj))
+    printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
+
+  // Big-endian 64-bit
+  if (const ELF64BEObjectFile *ELFObj = dyn_cast<ELF64BEObjectFile>(Obj))
+    printDynamicSection(ELFObj->getELFFile(), Obj->getFileName());
+}
diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index bbac90e74ed..610cd11365c 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -2153,8 +2153,10 @@ static void printFaultMaps(const ObjectFile *Obj) {
 }
 
 static void printPrivateFileHeaders(const ObjectFile *o, bool onlyFirst) {
-  if (o->isELF())
-    return printELFFileHeader(o);
+  if (o->isELF()) {
+    printELFFileHeader(o);
+    return printELFDynamicSection(o);
+  }
   if (o->isCOFF())
     return printCOFFFileHeader(o);
   if (o->isWasm())
diff --git a/llvm/tools/llvm-objdump/llvm-objdump.h b/llvm/tools/llvm-objdump/llvm-objdump.h
index c5a1ac8df9e..b2eb6e9d777 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.h
+++ b/llvm/tools/llvm-objdump/llvm-objdump.h
@@ -79,6 +79,7 @@ void printMachOBindTable(object::MachOObjectFile* o);
 void printMachOLazyBindTable(object::MachOObjectFile* o);
 void printMachOWeakBindTable(object::MachOObjectFile* o);
 void printELFFileHeader(const object::ObjectFile *o);
+void printELFDynamicSection(const object::ObjectFile *Obj);
 void printCOFFFileHeader(const object::ObjectFile *o);
 void printCOFFSymbolTable(const object::COFFImportFile *i);
 void printCOFFSymbolTable(const object::COFFObjectFile *o);