When getting an error location, don't assume that all sections prior to a given offset can be cast to an InputSection.

ELF/InputSection.cpp

for (Relocation &Rel : Relocations) {
     // after the name check.
     if (D->Type != STT_FUNC)
       continue;
 
     if (enclosingPrologueAdjusted(Rel.Offset, AdjustedPrologues))
       continue;
 
     if (Defined *F = getEnclosingFunction<ELFT>(Rel.Offset)) {
-      if (Target->adjustPrologueForCrossSplitStack(Buf + F->Value, End)) {
+      uint64_t SecOffset = 0;
+      if (auto *Sec = dyn_cast<InputSection>(this))
+        SecOffset = Sec->OutSecOff;
+      if (Target->adjustPrologueForCrossSplitStack(Buf + SecOffset + F->Value, End)) {
         AdjustedPrologues.insert(F);
         continue;
       }
     }
     if (!getFile<ELFT>()->SomeNoSplitStack)
       error("function call at " + getErrorLocation(Buf + Rel.Offset) +
             "crosses a split-stack boundary, but unable " +
             "to adjust the enclosing function's prologue");

ELF/Target.cpp

if (Config->EKind == ELF32LEKind)
       return getX32TargetInfo();
     return getX86_64TargetInfo();
   }
   fatal("unknown target machine");
 }
 
 template <class ELFT> static ErrorPlace getErrPlace(const uint8_t *Loc) {
   for (InputSectionBase *D : InputSections) {
-    auto *IS = cast<InputSection>(D);
-    if (!IS->getParent())
-      continue;
+    InputSection *IS = dyn_cast<InputSection>(D);
 
+    if (IS && IS->getParent()) {
       uint8_t *ISLoc = IS->getParent()->Loc + IS->OutSecOff;
       if (ISLoc <= Loc && Loc < ISLoc + IS->getSize())
         return {IS, IS->template getLocation<ELFT>(Loc - ISLoc) + ": "};
     }
+  }
   return {};
 }
 
 ErrorPlace elf::getErrorPlace(const uint8_t *Loc) {
   switch (Config->EKind) {
   case ELF32LEKind:
     return getErrPlace<ELF32LE>(Loc);
   case ELF32BEKind: