ELF2: Add DT_REL{,A}ENT and DT_SYMENT.

[ruiu]

Summary

According to the ELF specification, these dynamic array entries are mandatory.

[• rafael]

LGTM with a nit.

test/elf2/dynamic-reloc.s

48

You can check the numeric value, it is not going to change any time soon :-)

[Eugene.Zelenko]

Committed in r248952.

ELF/OutputSections.h

private:
   SymbolTableSection<ELFT> &DynSymSec;
   std::vector<uint32_t> Hashes;
 };
 
 template <class ELFT>
 class DynamicSection final : public OutputSectionBase<ELFT::Is64Bits> {
   typedef OutputSectionBase<ELFT::Is64Bits> Base;
   typedef typename Base::HeaderT HeaderT;
+  typedef typename llvm::object::ELFFile<ELFT>::Elf_Rel Elf_Rel;
+  typedef typename llvm::object::ELFFile<ELFT>::Elf_Rela Elf_Rela;
+  typedef typename llvm::object::ELFFile<ELFT>::Elf_Sym Elf_Sym;
 
 public:
   DynamicSection(SymbolTable &SymTab, HashTableSection<ELFT> &HashSec,
                  RelocationSection<ELFT> &RelaDynSec);
   void finalize() override;
   void writeTo(uint8_t *Buf) override;
 
 private:

ELF/OutputSections.cpp

 
 template <class ELFT> void DynamicSection<ELFT>::finalize() {
   typename Base::HeaderT &Header = this->Header;
   Header.sh_link = DynStrSec.getSectionIndex();
 
   unsigned NumEntries = 0;
   if (RelaDynSec.hasRelocs()) {
     ++NumEntries; // DT_RELA / DT_REL
-    ++NumEntries; // DT_RELASZ / DTRELSZ
+    ++NumEntries; // DT_RELASZ / DT_RELSZ
+    ++NumEntries; // DT_RELAENT / DT_RELENT
   }
   ++NumEntries; // DT_SYMTAB
+  ++NumEntries; // DT_SYMENT
   ++NumEntries; // DT_STRTAB
   ++NumEntries; // DT_STRSZ
   ++NumEntries; // DT_HASH
 
   StringRef RPath = Config->RPath;
   if (!RPath.empty()) {
     ++NumEntries; // DT_RUNPATH
     DynStrSec.add(RPath);
if (RelaDynSec.hasRelocs()) {
     bool IsRela = RelaDynSec.isRela();
     P->d_tag = IsRela ? DT_RELA : DT_REL;
     P->d_un.d_ptr = RelaDynSec.getVA();
     ++P;
 
     P->d_tag = IsRela ? DT_RELASZ : DT_RELSZ;
     P->d_un.d_val = RelaDynSec.getSize();
     ++P;
+
+    P->d_tag = IsRela ? DT_RELAENT : DT_RELENT;
+    P->d_un.d_val = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
+    ++P;
   }
 
   P->d_tag = DT_SYMTAB;
   P->d_un.d_ptr = DynSymSec.getVA();
   ++P;
 
+  P->d_tag = DT_SYMENT;
+  P->d_un.d_ptr = sizeof(Elf_Sym);
+  ++P;
+
   P->d_tag = DT_STRTAB;
   P->d_un.d_ptr = DynStrSec.getVA();
   ++P;
 
   P->d_tag = DT_STRSZ;
   P->d_un.d_val = DynStrSec.data().size();
   ++P;
 

test/elf2/dynamic-reloc.s

 // CHECK-NEXT:     }
 // CHECK-NEXT:   }
 // CHECK-NEXT: ]
 
 // CHECK: DynamicSection [
 // CHECK-NEXT:  Tag                Type                 Name/Value
 // CHECK-NEXT:  0x0000000000000007 RELA                 [[RELAADDR]]
 // CHECK-NEXT:  0x0000000000000008 RELASZ               [[RELASIZE]] (bytes)
+// CHECK-NEXT:  0x0000000000000009 RELAENT
 // CHECK-NEXT:  0x0000000000000006 SYMTAB
+// CHECK-NEXT:  0x000000000000000B SYMENT
 // CHECK-NEXT:  0x0000000000000005 STRTAB
 // CHECK-NEXT:  0x000000000000000A STRSZ
 // CHECK-NEXT:  0x0000000000000004 HASH
 // CHECK-NEXT:  0x0000000000000001 NEEDED               SharedLibrary ({{.*}}2.so)
 // CHECK-NEXT:  0x0000000000000000 NULL                 0x0
 // CHECK-NEXT: ]
 
 
 .global _start
 _start:
 .quad bar + 0x42
 call main

test/elf2/shared.s

 // CHECK:      Name: .rel.dyn
 // CHECK-NEXT: Type: SHT_REL
 // CHECK-NEXT: Flags [
 // CHECK-NEXT:   SHF_ALLOC
 // CHECK-NEXT: ]
 // CHECK-NEXT: Address: [[RELADDR:.*]]
 // CHECK-NEXT: Offset:
 // CHECK-NEXT: Size: [[RELSIZE:.*]]
+// CHECK-NEXT: Link:
+// CHECK-NEXT: Info:
+// CHECK-NEXT: AddressAlignment:
+// CHECK-NEXT: EntrySize: [[RELENT:.*]]
 
+// CHECK:      Name: .symtab
+// CHECK-NEXT: Type: SHT_SYMTAB
+// CHECK-NEXT: Flags [
+// CHECK-NEXT: ]
+// CHECK-NEXT: Address:
+// CHECK-NEXT: Offset:
+// CHECK-NEXT: Size:
+// CHECK-NEXT: Link:
+// CHECK-NEXT: Info:
+// CHECK-NEXT: AddressAlignment:
+// CHECK-NEXT: EntrySize: [[SYMENT:.*]]
 
 // CHECK:      Symbols [
 // CHECK-NEXT:   Symbol {
 // CHECK-NEXT:     Name:
 // CHECK-NEXT:     Value: 0x0
 // CHECK-NEXT:     Size: 0
 // CHECK-NEXT:     Binding: Local
 // CHECK-NEXT:     Type: None

 // DONT_EXPORT-NEXT:     Section: Undefined
 // DONT_EXPORT-NEXT:   }
 // DONT_EXPORT-NEXT: ]
 
 // CHECK:      DynamicSection [
 // CHECK-NEXT:   Tag        Type                 Name/Value
 // CHECK-NEXT:   0x00000011 REL                  [[RELADDR]]
 // CHECK-NEXT:   0x00000012 RELSZ                [[RELSIZE]] (bytes)
+// CHECK-NEXT:   0x00000013 RELENT               [[RELENT]] (bytes)
 // CHECK-NEXT:   0x00000006 SYMTAB               [[DYNSYMADDR]]
+// CHECK-NEXT:   0x0000000B SYMENT               [[SYMENT]] (bytes)
 // CHECK-NEXT:   0x00000005 STRTAB               [[DYNSTRADDR]]
 // CHECK-NEXT:   0x0000000A STRSZ
 // CHECK-NEXT:   0x00000004 HASH                 [[HASHADDR]]
 // CHECK-NEXT:   0x0000001D RUNPATH              foo:bar
 // CHECK-NEXT:   0x00000001 NEEDED               SharedLibrary ({{.*}}2.so)
 // CHECK-NEXT:   0x00000000 NULL                 0x0
 // CHECK-NEXT: ]