[BPF] Fix bpf llvm-objdump issues.

Commit https://reviews.llvm.org/D57939 ("[DWARF] Refactor
RelocVisitor and fix computation of SHT_RELA-typed relocation entries)
made a change for relocation resolution when operating
on an object file.

The change unfortunately broke BPF as given SymbolValue (S) and
Addent (A), previously relocation is resolved to
    S + A
and after the change, it is resolved to
    S

This patch fixed the issue by resolving relocation correctly.

It looks not all relocation resolution reaches here and I did not
trace down exactly when. But I do find if the object file includes
codes in two different ELF sections than default ".text",
the above bug will be triggered.

This patch included a trivial two function source code to
demonstrate this issue. The relocation for .debug_loc is resolved
incorrectly due to this and llvm-objdump cannot display source
annotated assembly.

Differential Revision: https://reviews.llvm.org/D66372

llvm-svn: 369199

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/Object/RelocationResolver.cpp b/llvm/lib/Object/RelocationResolver.cpp
index 8738e2e9f3b..7df4f8d2b90 100644
--- a/llvm/lib/Object/RelocationResolver.cpp
+++ b/llvm/lib/Object/RelocationResolver.cpp
@@ -90,9 +90,9 @@ static bool supportsBPF(uint64_t Type) {
 static uint64_t resolveBPF(RelocationRef R, uint64_t S, uint64_t A) {
   switch (R.getType()) {
   case ELF::R_BPF_64_32:
-    return S & 0xFFFFFFFF;
+    return (S + A) & 0xFFFFFFFF;
   case ELF::R_BPF_64_64:
-    return S;
+    return S + A;
   default:
     llvm_unreachable("Invalid relocation type");
   }