Reapply r260489.

Original commit message:

[readobj] Dump DT_JMPREL relocations when outputting dynamic relocations.

The bits of r260488 it depends on have been committed.

llvm-svn: 260970

2 files changed, 41 insertions, 0 deletions

diff --git a/llvm/test/Object/relocation-executable.test b/llvm/test/Object/relocation-executable.test
index 93d4dee3089..bb0bb157b6a 100644
--- a/llvm/test/Object/relocation-executable.test
+++ b/llvm/test/Object/relocation-executable.test
@@ -34,6 +34,18 @@ RUN:   %p/Inputs/hello-world.elf-x86-64 | FileCheck %s --check-prefix=DYN
 // DYN-NEXT:     Symbol: __gmon_start__
 // DYN-NEXT:     Addend: 0x0
 // DYN-NEXT:   }
+// DYN-NEXT:   Relocation {
+// DYN-NEXT:     Offset: 0x4018F8
+// DYN-NEXT:     Type: R_X86_64_JUMP_SLOT (7)
+// DYN-NEXT:     Symbol: __libc_start_main
+// DYN-NEXT:     Addend: 0x0
+// DYN-NEXT:   }
+// DYN-NEXT:   Relocation {
+// DYN-NEXT:     Offset: 0x401900
+// DYN-NEXT:     Type: R_X86_64_JUMP_SLOT (7)
+// DYN-NEXT:     Symbol: puts
+// DYN-NEXT:     Addend: 0x0
+// DYN-NEXT:   }
 // DYN-NEXT: }
 
 RUN: llvm-readobj -dyn-relocations -expand-relocs \
diff --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
index b8c815e4b35..f305d6d0d6c 100644
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -60,6 +60,8 @@ struct DynRegionInfo {
 
   template <typename Type> iterator_range<const Type *> getAsRange() const {
     const Type *Start = reinterpret_cast<const Type *>(Addr);
+    if (!Start)
+      return {Start, Start};
     if (EntSize != sizeof(Type) || Size % EntSize)
       reportError("Invalid entity size");
     return {Start, Start + (Size / EntSize)};
@@ -152,6 +154,7 @@ private:
   const ELFO *Obj;
   DynRegionInfo DynRelRegion;
   DynRegionInfo DynRelaRegion;
+  DynRegionInfo DynPLTRelRegion;
   const Elf_Phdr *DynamicProgHeader = nullptr;
   StringRef DynamicStringTable;
   const Elf_Sym *DynSymStart = nullptr;
@@ -1105,6 +1108,21 @@ void ELFDumper<ELFT>::parseDynamicTable(
     case ELF::DT_RELENT:
       DynRelRegion.EntSize = Dyn.getVal();
       break;
+    case ELF::DT_PLTREL:
+      if (Dyn.getVal() == DT_REL)
+        DynPLTRelRegion.EntSize = sizeof(Elf_Rel);
+      else if (Dyn.getVal() == DT_RELA)
+        DynPLTRelRegion.EntSize = sizeof(Elf_Rela);
+      else
+        reportError(Twine("unknown DT_PLTREL value of ") +
+                    Twine((uint64_t)Dyn.getVal()));
+      break;
+    case ELF::DT_JMPREL:
+      DynPLTRelRegion.Addr = toMappedAddr(Dyn.getPtr());
+      break;
+    case ELF::DT_PLTRELSZ:
+      DynPLTRelRegion.Size = Dyn.getVal();
+      break;
     }
   }
   if (StringTableBegin)
@@ -1246,6 +1264,17 @@ template <class ELFT> void ELFDumper<ELFT>::printDynamicRelocations() {
       Rela.r_addend = 0;
       printDynamicRelocation(Rela);
     }
+  if (DynPLTRelRegion.EntSize == sizeof(Elf_Rela))
+    for (const Elf_Rela &Rela : DynPLTRelRegion.getAsRange<Elf_Rela>())
+      printDynamicRelocation(Rela);
+  else
+    for (const Elf_Rel &Rel : DynPLTRelRegion.getAsRange<Elf_Rel>()) {
+      Elf_Rela Rela;
+      Rela.r_offset = Rel.r_offset;
+      Rela.r_info = Rel.r_info;
+      Rela.r_addend = 0;
+      printDynamicRelocation(Rela);
+    }
   W.unindent();
   W.startLine() << "}\n";
 }