8248186: Move CDS C++ vtable code to cppVtables.cpp

Reviewed-by: coleenp

Author: iklam

make/hotspot/lib/JvmFeatures.gmk

@@ -121,6 +121,7 @@ ifneq ($(call check-jvm-feature, cds), true)
       classListParser.cpp \
       classLoaderDataShared.cpp \
       classLoaderExt.cpp \
+      cppVtables.cpp \
       dumpAllocStats.cpp \
       dynamicArchive.cpp \
       filemap.cpp \

src/hotspot/share/memory/archiveBuilder.cpp

@@ -29,6 +29,7 @@
 #include "logging/logMessage.hpp"
 #include "memory/archiveBuilder.hpp"
 #include "memory/archiveUtils.hpp"
+#include "memory/cppVtables.hpp"
 #include "memory/dumpAllocStats.hpp"
 #include "memory/metaspaceShared.hpp"
 #include "memory/resourceArea.hpp"
@@ -479,7 +480,7 @@ void ArchiveBuilder::make_shallow_copy(DumpRegion *dump_region, SourceObjInfo* s
 
   memcpy(dest, src, bytes);
 
-  intptr_t* archived_vtable = MetaspaceShared::get_archived_cpp_vtable(ref->msotype(), (address)dest);
+  intptr_t* archived_vtable = CppVtables::get_archived_cpp_vtable(ref->msotype(), (address)dest);
   if (archived_vtable != NULL) {
     *(address*)dest = (address)archived_vtable;
     ArchivePtrMarker::mark_pointer((address*)dest);

src/hotspot/share/memory/cppVtables.cpp

@@ -0,0 +1,332 @@
+/*
+ * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "logging/log.hpp"
+#include "memory/archiveUtils.hpp"
+#include "memory/cppVtables.hpp"
+#include "memory/metaspaceShared.hpp"
+#include "oops/instanceClassLoaderKlass.hpp"
+#include "oops/instanceMirrorKlass.hpp"
+#include "oops/instanceRefKlass.hpp"
+#include "oops/methodData.hpp"
+#include "oops/objArrayKlass.hpp"
+#include "oops/typeArrayKlass.hpp"
+#include "runtime/arguments.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+// Objects of the Metadata types (such as Klass and ConstantPool) have C++ vtables.
+// (In GCC this is the field <Type>::_vptr, i.e., first word in the object.)
+//
+// Addresses of the vtables and the methods may be different across JVM runs,
+// if libjvm.so is dynamically loaded at a different base address.
+//
+// To ensure that the Metadata objects in the CDS archive always have the correct vtable:
+//
+// + at dump time:  we redirect the _vptr to point to our own vtables inside
+//                  the CDS image
+// + at run time:   we clone the actual contents of the vtables from libjvm.so
+//                  into our own tables.
+
+// Currently, the archive contain ONLY the following types of objects that have C++ vtables.
+#define CPP_VTABLE_PATCH_TYPES_DO(f) \
+  f(ConstantPool) \
+  f(InstanceKlass) \
+  f(InstanceClassLoaderKlass) \
+  f(InstanceMirrorKlass) \
+  f(InstanceRefKlass) \
+  f(Method) \
+  f(ObjArrayKlass) \
+  f(TypeArrayKlass)
+
+class CppVtableInfo {
+  intptr_t _vtable_size;
+  intptr_t _cloned_vtable[1];
+public:
+  static int num_slots(int vtable_size) {
+    return 1 + vtable_size; // Need to add the space occupied by _vtable_size;
+  }
+  int vtable_size()           { return int(uintx(_vtable_size)); }
+  void set_vtable_size(int n) { _vtable_size = intptr_t(n); }
+  intptr_t* cloned_vtable()   { return &_cloned_vtable[0]; }
+  void zero()                 { memset(_cloned_vtable, 0, sizeof(intptr_t) * vtable_size()); }
+  // Returns the address of the next CppVtableInfo that can be placed immediately after this CppVtableInfo
+  static size_t byte_size(int vtable_size) {
+    CppVtableInfo i;
+    return pointer_delta(&i._cloned_vtable[vtable_size], &i, sizeof(u1));
+  }
+};
+
+static inline intptr_t* vtable_of(Metadata* m) {
+  return *((intptr_t**)m);
+}
+
+static inline DumpRegion* mc_region() {
+  return MetaspaceShared::misc_code_dump_space();
+}
+
+template <class T> class CppVtableCloner : public T {
+  static CppVtableInfo* _info;
+
+  static int get_vtable_length(const char* name);
+
+public:
+  // Allocate and initialize the C++ vtable, starting from top, but do not go past end.
+  static intptr_t* allocate(const char* name);
+
+  // Clone the vtable to ...
+  static intptr_t* clone_vtable(const char* name, CppVtableInfo* info);
+
+  static void zero_vtable_clone() {
+    assert(DumpSharedSpaces, "dump-time only");
+    _info->zero();
+  }
+
+  static bool is_valid_shared_object(const T* obj) {
+    intptr_t* vptr = *(intptr_t**)obj;
+    return vptr == _info->cloned_vtable();
+  }
+
+  static void init_orig_cpp_vtptr(int kind);
+};
+
+template <class T> CppVtableInfo* CppVtableCloner<T>::_info = NULL;
+
+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->set_vtable_size(n);
+
+  intptr_t* p = clone_vtable(name, _info);
+  assert((char*)p == mc_region()->top(), "must be");
+
+  return _info->cloned_vtable();
+}
+
+template <class T>
+intptr_t* CppVtableCloner<T>::clone_vtable(const char* name, CppVtableInfo* info) {
+  if (!DumpSharedSpaces) {
+    assert(_info == 0, "_info is initialized only at dump time");
+    _info = info; // Remember it -- it will be used by MetaspaceShared::is_valid_shared_method()
+  }
+  T tmp; // Allocate temporary dummy metadata object to get to the original vtable.
+  int n = info->vtable_size();
+  intptr_t* srcvtable = vtable_of(&tmp);
+  intptr_t* dstvtable = info->cloned_vtable();
+
+  // We already checked (and, if necessary, adjusted n) when the vtables were allocated, so we are
+  // safe to do memcpy.
+  log_debug(cds, vtables)("Copying %3d vtable entries for %s", n, name);
+  memcpy(dstvtable, srcvtable, sizeof(intptr_t) * n);
+  return dstvtable + n;
+}
+
+// To determine the size of the vtable for each type, we use the following
+// trick by declaring 2 subclasses:
+//
+//   class CppVtableTesterA: public InstanceKlass {virtual int   last_virtual_method() {return 1;}    };
+//   class CppVtableTesterB: public InstanceKlass {virtual void* last_virtual_method() {return NULL}; };
+//
+// CppVtableTesterA and CppVtableTesterB's vtables have the following properties:
+// - Their size (N+1) is exactly one more than the size of InstanceKlass's vtable (N)
+// - The first N entries have are exactly the same as in InstanceKlass's vtable.
+// - Their last entry is different.
+//
+// So to determine the value of N, we just walk CppVtableTesterA and CppVtableTesterB's tables
+// and find the first entry that's different.
+//
+// This works on all C++ compilers supported by Oracle, but you may need to tweak it for more
+// esoteric compilers.
+
+template <class T> class CppVtableTesterB: public T {
+public:
+  virtual int last_virtual_method() {return 1;}
+};
+
+template <class T> class CppVtableTesterA : public T {
+public:
+  virtual void* last_virtual_method() {
+    // Make this different than CppVtableTesterB::last_virtual_method so the C++
+    // compiler/linker won't alias the two functions.
+    return NULL;
+  }
+};
+
+template <class T>
+int CppVtableCloner<T>::get_vtable_length(const char* name) {
+  CppVtableTesterA<T> a;
+  CppVtableTesterB<T> b;
+
+  intptr_t* avtable = vtable_of(&a);
+  intptr_t* bvtable = vtable_of(&b);
+
+  // Start at slot 1, because slot 0 may be RTTI (on Solaris/Sparc)
+  int vtable_len = 1;
+  for (; ; vtable_len++) {
+    if (avtable[vtable_len] != bvtable[vtable_len]) {
+      break;
+    }
+  }
+  log_debug(cds, vtables)("Found   %3d vtable entries for %s", vtable_len, name);
+
+  return vtable_len;
+}
+
+#define ALLOC_CPP_VTABLE_CLONE(c) \
+  _cloned_cpp_vtptrs[c##_Kind] = CppVtableCloner<c>::allocate(#c); \
+  ArchivePtrMarker::mark_pointer(&_cloned_cpp_vtptrs[c##_Kind]);
+
+#define CLONE_CPP_VTABLE(c) \
+  p = CppVtableCloner<c>::clone_vtable(#c, (CppVtableInfo*)p);
+
+#define ZERO_CPP_VTABLE(c) \
+ CppVtableCloner<c>::zero_vtable_clone();
+
+#define INIT_ORIG_CPP_VTPTRS(c) \
+  CppVtableCloner<c>::init_orig_cpp_vtptr(c##_Kind);
+
+#define DECLARE_CLONED_VTABLE_KIND(c) c ## _Kind,
+
+enum ClonedVtableKind {
+  // E.g., ConstantPool_Kind == 0, InstanceKlass_Kind == 1, etc.
+  CPP_VTABLE_PATCH_TYPES_DO(DECLARE_CLONED_VTABLE_KIND)
+  _num_cloned_vtable_kinds
+};
+
+// This is a map of all the original vtptrs. E.g., for
+//     ConstantPool *cp = new (...) ConstantPool(...) ; // a dynamically allocated constant pool
+// the following holds true:
+//     _orig_cpp_vtptrs[ConstantPool_Kind] ==  ((intptr_t**)cp)[0]
+static intptr_t* _orig_cpp_vtptrs[_num_cloned_vtable_kinds];
+static bool _orig_cpp_vtptrs_inited = false;
+
+template <class T>
+void CppVtableCloner<T>::init_orig_cpp_vtptr(int kind) {
+  assert(kind < _num_cloned_vtable_kinds, "sanity");
+  T tmp; // Allocate temporary dummy metadata object to get to the original vtable.
+  intptr_t* srcvtable = vtable_of(&tmp);
+  _orig_cpp_vtptrs[kind] = srcvtable;
+}
+
+// This is the index of all the cloned vtables. E.g., for
+//     ConstantPool* cp = ....; // an archived constant pool
+//     InstanceKlass* ik = ....;// an archived class
+// the following holds true:
+//     _cloned_cpp_vtptrs[ConstantPool_Kind]  == ((intptr_t**)cp)[0]
+//     _cloned_cpp_vtptrs[InstanceKlass_Kind] == ((intptr_t**)ik)[0]
+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*));
+}
+
+void CppVtables::serialize_cloned_cpp_vtptrs(SerializeClosure* soc) {
+  soc->do_ptr((void**)&_cloned_cpp_vtptrs);
+}
+
+intptr_t* CppVtables::get_archived_cpp_vtable(MetaspaceObj::Type msotype, address obj) {
+  if (!_orig_cpp_vtptrs_inited) {
+    CPP_VTABLE_PATCH_TYPES_DO(INIT_ORIG_CPP_VTPTRS);
+    _orig_cpp_vtptrs_inited = true;
+  }
+
+  Arguments::assert_is_dumping_archive();
+  int kind = -1;
+  switch (msotype) {
+  case MetaspaceObj::SymbolType:
+  case MetaspaceObj::TypeArrayU1Type:
+  case MetaspaceObj::TypeArrayU2Type:
+  case MetaspaceObj::TypeArrayU4Type:
+  case MetaspaceObj::TypeArrayU8Type:
+  case MetaspaceObj::TypeArrayOtherType:
+  case MetaspaceObj::ConstMethodType:
+  case MetaspaceObj::ConstantPoolCacheType:
+  case MetaspaceObj::AnnotationsType:
+  case MetaspaceObj::MethodCountersType:
+  case MetaspaceObj::RecordComponentType:
+    // These have no vtables.
+    break;
+  case MetaspaceObj::MethodDataType:
+    // We don't archive MethodData <-- should have been removed in removed_unsharable_info
+    ShouldNotReachHere();
+    break;
+  default:
+    for (kind = 0; kind < _num_cloned_vtable_kinds; kind ++) {
+      if (vtable_of((Metadata*)obj) == _orig_cpp_vtptrs[kind]) {
+        break;
+      }
+    }
+    if (kind >= _num_cloned_vtable_kinds) {
+      fatal("Cannot find C++ vtable for " INTPTR_FORMAT " -- you probably added"
+            " a new subtype of Klass or MetaData without updating CPP_VTABLE_PATCH_TYPES_DO",
+            p2i(obj));
+    }
+  }
+
+  if (kind >= 0) {
+    assert(kind < _num_cloned_vtable_kinds, "must be");
+    return _cloned_cpp_vtptrs[kind];
+  } else {
+    return NULL;
+  }
+}
+
+// This can be called at both dump time and run time:
+// - clone the contents of the c++ vtables into the space
+//   allocated by allocate_cpp_vtable_clones()
+void CppVtables::clone_cpp_vtables(intptr_t* p) {
+  assert(DumpSharedSpaces || UseSharedSpaces, "sanity");
+  CPP_VTABLE_PATCH_TYPES_DO(CLONE_CPP_VTABLE);
+}
+
+void CppVtables::zero_cpp_vtable_clones_for_writing() {
+  assert(DumpSharedSpaces, "dump-time only");
+  CPP_VTABLE_PATCH_TYPES_DO(ZERO_CPP_VTABLE);
+}
+
+// Allocate and initialize the C++ vtables, starting from top, but do not go past end.
+char* CppVtables::allocate_cpp_vtable_clones() {
+  char* cloned_vtables = mc_region()->top(); // This is the beginning of all the cloned vtables
+
+  assert(DumpSharedSpaces, "dump-time only");
+  // Layout (each slot is a intptr_t):
+  //   [number of slots in the first vtable = n1]
+  //   [ <n1> slots for the first vtable]
+  //   [number of slots in the first second = n2]
+  //   [ <n2> slots for the second vtable]
+  //   ...
+  // The order of the vtables is the same as the CPP_VTAB_PATCH_TYPES_DO macro.
+  CPP_VTABLE_PATCH_TYPES_DO(ALLOC_CPP_VTABLE_CLONE);
+
+  return cloned_vtables;
+}
+
+bool CppVtables::is_valid_shared_method(const Method* m) {
+  assert(MetaspaceShared::is_in_shared_metaspace(m), "must be");
+  return CppVtableCloner<Method>::is_valid_shared_object(m);
+}