[PATCH] D33403: [RuntimeDyld, PowerPC] Fix relocation detection overflow

[Ulrich Weigand via Phabricator via llvm-commits]

uweigand created this revision.
Herald added a subscriber: nemanjai.

Code in RuntimeDyldELF currently uses 32-bit temporaries to detect whether a PPC64 relocation target is out of range.  This is incorrect, and can mis-detect overflow where the distance between relocation site and target is close to a multiple of 4GB.  Fixed by using 64-bit temporaries.

Noticed while debugging PR32650.


https://reviews.llvm.org/D33403

Files:
  lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp


Index: lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
===================================================================
--- lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
+++ lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
@@ -737,23 +737,23 @@
     writeInt16BE(LocalAddress, applyPPCha(Delta));
   } break;
   case ELF::R_PPC64_ADDR32: {
-    int32_t Result = static_cast<int32_t>(Value + Addend);
-    if (SignExtend32<32>(Result) != Result)
+    int64_t Result = static_cast<int64_t>(Value + Addend);
+    if (SignExtend64<32>(Result) != Result)
       llvm_unreachable("Relocation R_PPC64_ADDR32 overflow");
     writeInt32BE(LocalAddress, Result);
   } break;
   case ELF::R_PPC64_REL24: {
     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
-    int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
-    if (SignExtend32<26>(delta) != delta)
+    int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
+    if (SignExtend64<26>(delta) != delta)
       llvm_unreachable("Relocation R_PPC64_REL24 overflow");
     // Generates a 'bl <address>' instruction
     writeInt32BE(LocalAddress, 0x48000001 | (delta & 0x03FFFFFC));
   } break;
   case ELF::R_PPC64_REL32: {
     uint64_t FinalAddress = Section.getLoadAddressWithOffset(Offset);
-    int32_t delta = static_cast<int32_t>(Value - FinalAddress + Addend);
-    if (SignExtend32<32>(delta) != delta)
+    int64_t delta = static_cast<int64_t>(Value - FinalAddress + Addend);
+    if (SignExtend64<32>(delta) != delta)
       llvm_unreachable("Relocation R_PPC64_REL32 overflow");
     writeInt32BE(LocalAddress, delta);
   } break;
@@ -1344,9 +1344,9 @@
         }
         uint8_t *RelocTarget =
             Sections[Value.SectionID].getAddressWithOffset(Value.Addend);
-        int32_t delta = static_cast<int32_t>(Target - RelocTarget);
+        int64_t delta = static_cast<int64_t>(Target - RelocTarget);
         // If it is within 26-bits branch range, just set the branch target
-        if (SignExtend32<26>(delta) == delta) {
+        if (SignExtend64<26>(delta) == delta) {
           RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
           if (Value.SymbolName)
             addRelocationForSymbol(RE, Value.SymbolName);


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