[PATCH] D33402: [RuntimeDyld, PowerPC] Fix check for external symbols when detecting reloction overflow

[Ulrich Weigand via Phabricator via llvm-commits]

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

The PowerPC part of processRelocationRef currently assumes that external symbols can be identified by checking for SymType == SymbolRef::ST_Unknown.   This is actually incorrect in some cases, causing relocation overflows to be mis-detected.  The correct check is to test whether Value.SymbolName is null.

Fixes PR32650.


https://reviews.llvm.org/D33402

Files:
  lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp


Index: lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
===================================================================
--- lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
+++ lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
@@ -1324,12 +1324,12 @@
       Obj.getPlatformFlags(AbiVariant);
       AbiVariant &= ELF::EF_PPC64_ABI;
       // A PPC branch relocation will need a stub function if the target is
-      // an external symbol (Symbol::ST_Unknown) or if the target address
+      // an external symbol (Value.SymbolName set) or if the target address
       // is not within the signed 24-bits branch address.
       SectionEntry &Section = Sections[SectionID];
       uint8_t *Target = Section.getAddressWithOffset(Offset);
       bool RangeOverflow = false;
-      if (SymType != SymbolRef::ST_Unknown) {
+      if (!Value.SymbolName) {
         if (AbiVariant != 2) {
           // In the ELFv1 ABI, a function call may point to the .opd entry,
           // so the final symbol value is calculated based on the relocation
@@ -1348,15 +1348,12 @@
         // If it is within 26-bits branch range, just set the branch target
         if (SignExtend32<26>(delta) == delta) {
           RelocationEntry RE(SectionID, Offset, RelType, Value.Addend);
-          if (Value.SymbolName)
-            addRelocationForSymbol(RE, Value.SymbolName);
-          else
-            addRelocationForSection(RE, Value.SectionID);
+          addRelocationForSection(RE, Value.SectionID);
         } else {
           RangeOverflow = true;
         }
       }
-      if (SymType == SymbolRef::ST_Unknown || RangeOverflow) {
+      if (Value.SymbolName || RangeOverflow) {
         // It is an external symbol (SymbolRef::ST_Unknown) or within a range
         // larger than 24-bits.
         StubMap::const_iterator i = Stubs.find(Value);
@@ -1412,7 +1409,7 @@
                             RelType, 0);
           Section.advanceStubOffset(getMaxStubSize());
         }
-        if (SymType == SymbolRef::ST_Unknown) {
+        if (Value.SymbolName) {
           // Restore the TOC for external calls
           if (AbiVariant == 2)
             writeInt32BE(Target + 4, 0xE8410018); // ld r2,28(r1)


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