8224509: Incorrect alignment in CDS related allocation code on 32-bit platforms

Reviewed-by: iklam, stuefe

Author: calvinccheung

src/hotspot/share/classfile/systemDictionaryShared.cpp

@@ -2053,6 +2053,7 @@ InstanceKlass* SystemDictionaryShared::find_builtin_class(Symbol* name) {
   const RunTimeSharedClassInfo* record = find_record(&_builtin_dictionary, &_dynamic_builtin_dictionary, name);
   if (record != NULL) {
     assert(!record->_klass->is_hidden(), "hidden class cannot be looked up by name");
+    assert(check_alignment(record->_klass), "Address not aligned");
     return record->_klass;
   } else {
     return NULL;

src/hotspot/share/memory/archiveBuilder.cpp

@@ -460,7 +460,6 @@ void ArchiveBuilder::make_shallow_copy(DumpRegion *dump_region, SourceObjInfo* s
   address src = ref->obj();
   int bytes = src_info->size_in_bytes();
   char* dest;
-  size_t alignment = BytesPerWord;
   char* oldtop;
   char* newtop;
 
@@ -473,10 +472,10 @@ void ArchiveBuilder::make_shallow_copy(DumpRegion *dump_region, SourceObjInfo* s
     Klass* klass = (Klass*)src;
     if (klass->is_instance_klass()) {
       SystemDictionaryShared::validate_before_archiving(InstanceKlass::cast(klass));
-      dump_region->allocate(sizeof(address), BytesPerWord);
+      dump_region->allocate(sizeof(address));
     }
   }
-  dest = dump_region->allocate(bytes, alignment);
+  dest = dump_region->allocate(bytes);
   newtop = dump_region->top();
 
   memcpy(dest, src, bytes);

src/hotspot/share/memory/archiveUtils.cpp

@@ -37,6 +37,10 @@ address* ArchivePtrMarker::_ptr_base;
 address* ArchivePtrMarker::_ptr_end;
 bool ArchivePtrMarker::_compacted;
 
+// Metaspace::allocate() requires that all blocks must be aligned with KlassAlignmentInBytes.
+// We enforce the same alignment rule in blocks allocated from the shared space.
+const int SharedSpaceObjectAlignment = KlassAlignmentInBytes;
+
 void ArchivePtrMarker::initialize(CHeapBitMap* ptrmap, address* ptr_base, address* ptr_end) {
   assert(_ptrmap == NULL, "initialize only once");
   _ptr_base = ptr_base;
@@ -165,9 +169,9 @@ char* DumpRegion::expand_top_to(char* newtop) {
   return _top;
 }
 
-char* DumpRegion::allocate(size_t num_bytes, size_t alignment) {
-  char* p = (char*)align_up(_top, alignment);
-  char* newtop = p + align_up(num_bytes, alignment);
+char* DumpRegion::allocate(size_t num_bytes) {
+  char* p = (char*)align_up(_top, (size_t)SharedSpaceObjectAlignment);
+  char* newtop = p + align_up(num_bytes, (size_t)SharedSpaceObjectAlignment);
   expand_top_to(newtop);
   memset(p, 0, newtop - p);
   return p;

src/hotspot/share/memory/archiveUtils.hpp

@@ -157,7 +157,7 @@ class DumpRegion {
   DumpRegion(const char* name) : _name(name), _base(NULL), _top(NULL), _end(NULL), _is_packed(false) {}
 
   char* expand_top_to(char* newtop);
-  char* allocate(size_t num_bytes, size_t alignment=BytesPerWord);
+  char* allocate(size_t num_bytes);
 
   void append_intptr_t(intptr_t n, bool need_to_mark = false);
 

src/hotspot/share/memory/cppVtables.cpp

@@ -117,7 +117,7 @@ template <class T>
 intptr_t* CppVtableCloner<T>::allocate(const char* name) {
   assert(is_aligned(mc_region()->top(), sizeof(intptr_t)), "bad alignment");
   int n = get_vtable_length(name);
-  _info = (CppVtableInfo*)mc_region()->allocate(CppVtableInfo::byte_size(n), sizeof(intptr_t));
+  _info = (CppVtableInfo*)mc_region()->allocate(CppVtableInfo::byte_size(n));
   _info->set_vtable_size(n);
 
   intptr_t* p = clone_vtable(name, _info);
@@ -242,7 +242,7 @@ static intptr_t** _cloned_cpp_vtptrs = NULL;
 void CppVtables::allocate_cloned_cpp_vtptrs() {
   assert(DumpSharedSpaces, "must");
   size_t vtptrs_bytes = _num_cloned_vtable_kinds * sizeof(intptr_t*);
-  _cloned_cpp_vtptrs = (intptr_t**)mc_region()->allocate(vtptrs_bytes, sizeof(intptr_t*));
+  _cloned_cpp_vtptrs = (intptr_t**)mc_region()->allocate(vtptrs_bytes);
 }
 
 void CppVtables::serialize_cloned_cpp_vtptrs(SerializeClosure* soc) {