[LLDB][ObjectFileELF] Correct the return type of RelocOffset64 and RelocAddend64

[SixWeining]

Summary

According to /usr/include/elf.h and lldb/source/Plugins/ObjectFile/ELF/ELFHeader.h.
For ELF64 relocation, types of offset and addend should be elf_addr and elf_sxword.

Depends on D145462.

[DavidSpickett]

Seems to me that member functions of ELFRelocation should use the typedefs from lldb/source/Plugins/ObjectFile/ELF/ELFHeader.h where there is one. elf_sxword for example.

If you want to do that in another patch, that's fine. Just in case some test case is relying on the uin64_t -> unsigned down cast unintentionally.

lldb/test/Shell/ObjectFile/ELF/loongarch64-relocations.yaml

37–41

I'm not familiar with how these relocation are processed, would it be better to use something with the sign bit set here? Or does it not matter, the value is just copied into .debug_info verbatim anyway.

[SixWeining]

In D145550#4177291, @DavidSpickett wrote:

Seems to me that member functions of ELFRelocation should use the typedefs from lldb/source/Plugins/ObjectFile/ELF/ELFHeader.h where there is one. elf_sxword for example.

If you want to do that in another patch, that's fine. Just in case some test case is relying on the uin64_t -> unsigned down cast unintentionally.

Yes, I agree. Let me do that in another patch. Thanks.

lldb/test/Shell/ObjectFile/ELF/loongarch64-relocations.yaml

37–41

For this case, it is processed by below code:

2596 static void ApplyELF64ABS64Relocation(Symtab *symtab, ELFRelocation &rel,
2597                                       DataExtractor &debug_data,
2598                                       Section *rel_section) {
2599   Symbol *symbol = symtab->FindSymbolByID(ELFRelocation::RelocSymbol64(rel));
2600   if (symbol) {
2601     addr_t value = symbol->GetAddressRef().GetFileAddress();
2602     DataBufferSP &data_buffer_sp = debug_data.GetSharedDataBuffer(); 
2603     // ObjectFileELF creates a WritableDataBuffer in CreateInstance.
2604     WritableDataBuffer *data_buffer =
2605         llvm::cast<WritableDataBuffer>(data_buffer_sp.get());
2606     uint64_t *dst = reinterpret_cast<uint64_t *>(
2607         data_buffer->GetBytes() + rel_section->GetFileOffset() +
2608         ELFRelocation::RelocOffset64(rel));
2609     uint64_t val_offset = value + ELFRelocation::RelocAddend64(rel);
2610     memcpy(dst, &val_offset, sizeof(uint64_t));
2611   }
2612 }

Memcpy S + A to .debug_info.

I can add another relocation entry with the sign bit set.

[SixWeining]

Address @DavidSpickett's comments.

[DavidSpickett]

LGTM.

lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

public:
   static unsigned RelocType64(const ELFRelocation &rel);
 
   static unsigned RelocSymbol32(const ELFRelocation &rel);
 
   static unsigned RelocSymbol64(const ELFRelocation &rel);
 
   static unsigned RelocOffset32(const ELFRelocation &rel);
 
-  static unsigned RelocOffset64(const ELFRelocation &rel);
+  static elf_addr RelocOffset64(const ELFRelocation &rel);
 
   static unsigned RelocAddend32(const ELFRelocation &rel);
 
-  static unsigned RelocAddend64(const ELFRelocation &rel);
+  static elf_sxword RelocAddend64(const ELFRelocation &rel);
 
   bool IsRela() { return (reloc.is<ELFRela *>()); }
 
 private:
   typedef llvm::PointerUnion<ELFRel *, ELFRela *> RelocUnion;
 
   RelocUnion reloc;
 };

 
 unsigned ELFRelocation::RelocOffset32(const ELFRelocation &rel) {
   if (rel.reloc.is<ELFRel *>())
     return rel.reloc.get<ELFRel *>()->r_offset;
   else
     return rel.reloc.get<ELFRela *>()->r_offset;
 }
 
-unsigned ELFRelocation::RelocOffset64(const ELFRelocation &rel) {
+elf_addr ELFRelocation::RelocOffset64(const ELFRelocation &rel) {
   if (rel.reloc.is<ELFRel *>())
     return rel.reloc.get<ELFRel *>()->r_offset;
   else
     return rel.reloc.get<ELFRela *>()->r_offset;
 }
 
 unsigned ELFRelocation::RelocAddend32(const ELFRelocation &rel) {
   if (rel.reloc.is<ELFRel *>())
     return 0;
   else
     return rel.reloc.get<ELFRela *>()->r_addend;
 }
 
-unsigned ELFRelocation::RelocAddend64(const ELFRelocation &rel) {
+elf_sxword  ELFRelocation::RelocAddend64(const ELFRelocation &rel) {
   if (rel.reloc.is<ELFRel *>())
     return 0;
   else
     return rel.reloc.get<ELFRela *>()->r_addend;
 }
 
 static user_id_t SegmentID(size_t PHdrIndex) {
   return ~user_id_t(PHdrIndex);

lldb/test/Shell/ObjectFile/ELF/loongarch64-relocations.yaml

 # RUN: yaml2obj %s -o %t
 # RUN: lldb-test object-file -contents %t | FileCheck %s
 
 ## Test that relocations are correctly applied to the .debug_info section on loongarch64.
 
 # CHECK:      Name: .debug_info
 # CHECK:      Data:  (
 ## Before relocation:
-##                0000: 00000000 00000000 00000000
+##                0000: 00000000 00000000 00000000 00000000 00000000
 ## After relocation:
-# CHECK-NEXT:     0000: 34120000 78560000 00000000
+# CHECK-NEXT:     0000: 34120000 88776655 44332211 8899AABB CCDDEEFF
 # CHECK-NEXT: )
 
 --- !ELF
 FileHeader:
   Class:           ELFCLASS64
   Data:            ELFDATA2LSB
   Type:            ET_REL
   Machine:         EM_LOONGARCH
 Sections:
   - Name:            .debug_str
     Type:            SHT_PROGBITS
   - Name:            .debug_info
     Type:            SHT_PROGBITS
-    Content:         000000000000000000000000
+    Content:         0000000000000000000000000000000000000000
   - Name:            .rela.debug_info
     Type:            SHT_RELA
     Info:            .debug_info
     Relocations:
       - Offset:          0x0000000000000000
         Symbol:          .debug_str
         Type:            R_LARCH_32
         Addend:          0x1234
       - Offset:          0x0000000000000004
         Symbol:          .debug_str
         Type:            R_LARCH_64
-        Addend:          0x5678
+        Addend:          0x1122334455667788
+      - Offset:          0x000000000000000C
+        Symbol:          .debug_str
+        Type:            R_LARCH_64
+        Addend:          0xFFEEDDCCBBAA9988
 Symbols:
   - Name:            .debug_str
     Type:            STT_SECTION
     Section:         .debug_str
   - Name:            .debug_info
     Type:            STT_SECTION
     Section:         .debug_info
 ...