Add a relocation for R_AARCH64_ABS32 in ObjectFileELF

[lanza]

Summary

.rela.debug_info relocations are being done via
ObjectFileELF::ApplyRelocations for aarch64. Currently, the switch case
that iterates over the relocation type is only implemented for a few
different types and assert(false)es over the rest.

Implement the relocation for R_AARCH64_ABS32 in ApplyRelocations

[peter.smith]

Speaking as primarily a linker person; the implementation of the R_AARCH64_ABS32 relocation is correct. You'll need to get some input from an LLDB person about whether extending the function like this is the right approach though, I'm guessing that there are more than just AArch64 and Arm that support relocated debug sections? The more codes that are added the less readable that assert is going to get. Final comment: is there a test case that you can add to show that R_AARCH64_ABS32 is handled correctly, or even just doesn't assert fail?

source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

2705–2706

Is it worth refactoring this assert a little bit. At a microscopic level both

(reloc_type(rel) == R_AARCH64_ABS32 && (value <= UINT32_MAX)));

and

(reloc_type(rel) == R_X86_64_32 && (value <= UINT32_MAX))

are really an instance of:

(IsRelocABS32(rel) && value <= UINT32_MAX)

Where IsRelocABS32 could abstract away the target specific relocation codes.

2705–2706

Not related to this change, just a drive by comment. Should this be an error message and not an assert? If this can happen due to bad input objects (too much debug information) then it would be helpful to the user to have an error message rather than an assert failure.

[lanza]

Refactor assert code

[lanza]

Convert assert to a log

[lanza]

fix typo

source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp

if (hdr->Is32Bit()) {
           uint64_t *dst = reinterpret_cast<uint64_t *>(
               data_buffer_sp->GetBytes() + rel_section->GetFileOffset() +
               ELFRelocation::RelocOffset64(rel));
           *dst = value + ELFRelocation::RelocAddend64(rel);
         }
         break;
       }
       case R_X86_64_32:
-      case R_X86_64_32S: {
+      case R_X86_64_32S:
+      case R_AARCH64_ABS32: {
         symbol = symtab->FindSymbolByID(reloc_symbol(rel));
         if (symbol) {
           addr_t value = symbol->GetAddressRef().GetFileAddress();
           value += ELFRelocation::RelocAddend32(rel);
-          assert(
-              (reloc_type(rel) == R_X86_64_32 && (value <= UINT32_MAX)) ||
+          if (!((IsRelocABS32(rel) && value <= UINT32_MAX) ||
                 (reloc_type(rel) == R_X86_64_32S &&
-               ((int64_t)value <= INT32_MAX && (int64_t)value >= INT32_MIN)));
+                 ((int64_t)value <= INT32_MAX &&
+                  (int64_t)value >= INT32_MIN)))) {
+            Log *log =
+                lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_MODULES);
+            log->Printf("Failed to apply debug info relocations");
+          }
           uint32_t truncated_addr = (value & 0xFFFFFFFF);
           DataBufferSP &data_buffer_sp = debug_data.GetSharedDataBuffer();
           uint32_t *dst = reinterpret_cast<uint32_t *>(
               data_buffer_sp->GetBytes() + rel_section->GetFileOffset() +
               ELFRelocation::RelocOffset32(rel));
           *dst = truncated_addr;
         }
         break;