1 /* 2 * Copyright (c) 2020, 2023, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "cds/archiveUtils.hpp" 27 #include "cds/archiveBuilder.hpp" 28 #include "cds/cdsConfig.hpp" 29 #include "cds/cppVtables.hpp" 30 #include "cds/metaspaceShared.hpp" 31 #include "logging/log.hpp" 32 #include "oops/flatArrayKlass.hpp" 33 #include "oops/inlineKlass.hpp" 34 #include "oops/instanceClassLoaderKlass.hpp" 35 #include "oops/instanceKlass.inline.hpp" 36 #include "oops/instanceMirrorKlass.hpp" 37 #include "oops/instanceRefKlass.hpp" 38 #include "oops/instanceStackChunkKlass.hpp" 39 #include "oops/methodData.hpp" 40 #include "oops/objArrayKlass.hpp" 41 #include "oops/typeArrayKlass.hpp" 42 #include "runtime/arguments.hpp" 43 #include "utilities/globalDefinitions.hpp" 44 45 // Objects of the Metadata types (such as Klass and ConstantPool) have C++ vtables. 46 // (In GCC this is the field <Type>::_vptr, i.e., first word in the object.) 47 // 48 // Addresses of the vtables and the methods may be different across JVM runs, 49 // if libjvm.so is dynamically loaded at a different base address. 50 // 51 // To ensure that the Metadata objects in the CDS archive always have the correct vtable: 52 // 53 // + at dump time: we redirect the _vptr to point to our own vtables inside 54 // the CDS image 55 // + at run time: we clone the actual contents of the vtables from libjvm.so 56 // into our own tables. 57 58 // Currently, the archive contains ONLY the following types of objects that have C++ vtables. 59 // NOTE: this table must be in-sync with sun.jvm.hotspot.memory.FileMapInfo::populateMetadataTypeArray(). 60 #define CPP_VTABLE_TYPES_DO(f) \ 61 f(ConstantPool) \ 62 f(InstanceKlass) \ 63 f(InstanceClassLoaderKlass) \ 64 f(InstanceMirrorKlass) \ 65 f(InstanceRefKlass) \ 66 f(InstanceStackChunkKlass) \ 67 f(Method) \ 68 f(ObjArrayKlass) \ 69 f(TypeArrayKlass) \ 70 f(FlatArrayKlass) \ 71 f(InlineKlass) 72 73 class CppVtableInfo { 74 intptr_t _vtable_size; 75 intptr_t _cloned_vtable[1]; 76 public: 77 static int num_slots(int vtable_size) { 78 return 1 + vtable_size; // Need to add the space occupied by _vtable_size; 79 } 80 int vtable_size() { return int(uintx(_vtable_size)); } 81 void set_vtable_size(int n) { _vtable_size = intptr_t(n); } 82 intptr_t* cloned_vtable() { return &_cloned_vtable[0]; } 83 void zero() { memset(_cloned_vtable, 0, sizeof(intptr_t) * vtable_size()); } 84 // Returns the address of the next CppVtableInfo that can be placed immediately after this CppVtableInfo 85 static size_t byte_size(int vtable_size) { 86 CppVtableInfo i; 87 return pointer_delta(&i._cloned_vtable[vtable_size], &i, sizeof(u1)); 88 } 89 }; 90 91 static inline intptr_t* vtable_of(const Metadata* m) { 92 return *((intptr_t**)m); 93 } 94 95 template <class T> class CppVtableCloner { 96 static int get_vtable_length(const char* name); 97 98 public: 99 // Allocate a clone of the vtable of T from the shared metaspace; 100 // Initialize the contents of this clone. 101 static CppVtableInfo* allocate_and_initialize(const char* name); 102 103 // Copy the contents of the vtable of T into info->_cloned_vtable; 104 static void initialize(const char* name, CppVtableInfo* info); 105 106 static void init_orig_cpp_vtptr(int kind); 107 }; 108 109 template <class T> 110 CppVtableInfo* CppVtableCloner<T>::allocate_and_initialize(const char* name) { 111 int n = get_vtable_length(name); 112 CppVtableInfo* info = 113 (CppVtableInfo*)ArchiveBuilder::current()->rw_region()->allocate(CppVtableInfo::byte_size(n)); 114 info->set_vtable_size(n); 115 initialize(name, info); 116 return info; 117 } 118 119 template <class T> 120 void CppVtableCloner<T>::initialize(const char* name, CppVtableInfo* info) { 121 T tmp; // Allocate temporary dummy metadata object to get to the original vtable. 122 int n = info->vtable_size(); 123 intptr_t* srcvtable = vtable_of(&tmp); 124 intptr_t* dstvtable = info->cloned_vtable(); 125 126 // We already checked (and, if necessary, adjusted n) when the vtables were allocated, so we are 127 // safe to do memcpy. 128 log_debug(cds, vtables)("Copying %3d vtable entries for %s", n, name); 129 memcpy(dstvtable, srcvtable, sizeof(intptr_t) * n); 130 } 131 132 // To determine the size of the vtable for each type, we use the following 133 // trick by declaring 2 subclasses: 134 // 135 // class CppVtableTesterA: public InstanceKlass {virtual int last_virtual_method() {return 1;} }; 136 // class CppVtableTesterB: public InstanceKlass {virtual void* last_virtual_method() {return nullptr}; }; 137 // 138 // CppVtableTesterA and CppVtableTesterB's vtables have the following properties: 139 // - Their size (N+1) is exactly one more than the size of InstanceKlass's vtable (N) 140 // - The first N entries have are exactly the same as in InstanceKlass's vtable. 141 // - Their last entry is different. 142 // 143 // So to determine the value of N, we just walk CppVtableTesterA and CppVtableTesterB's tables 144 // and find the first entry that's different. 145 // 146 // This works on all C++ compilers supported by Oracle, but you may need to tweak it for more 147 // esoteric compilers. 148 149 template <class T> class CppVtableTesterB: public T { 150 public: 151 virtual int last_virtual_method() {return 1;} 152 }; 153 154 template <class T> class CppVtableTesterA : public T { 155 public: 156 virtual void* last_virtual_method() { 157 // Make this different than CppVtableTesterB::last_virtual_method so the C++ 158 // compiler/linker won't alias the two functions. 159 return nullptr; 160 } 161 }; 162 163 template <class T> 164 int CppVtableCloner<T>::get_vtable_length(const char* name) { 165 CppVtableTesterA<T> a; 166 CppVtableTesterB<T> b; 167 168 intptr_t* avtable = vtable_of(&a); 169 intptr_t* bvtable = vtable_of(&b); 170 171 // Start at slot 1, because slot 0 may be RTTI (on Solaris/Sparc) 172 int vtable_len = 1; 173 for (; ; vtable_len++) { 174 if (avtable[vtable_len] != bvtable[vtable_len]) { 175 break; 176 } 177 } 178 log_debug(cds, vtables)("Found %3d vtable entries for %s", vtable_len, name); 179 180 return vtable_len; 181 } 182 183 #define ALLOCATE_AND_INITIALIZE_VTABLE(c) \ 184 _index[c##_Kind] = CppVtableCloner<c>::allocate_and_initialize(#c); \ 185 ArchivePtrMarker::mark_pointer(&_index[c##_Kind]); 186 187 #define INITIALIZE_VTABLE(c) \ 188 CppVtableCloner<c>::initialize(#c, _index[c##_Kind]); 189 190 #define INIT_ORIG_CPP_VTPTRS(c) \ 191 CppVtableCloner<c>::init_orig_cpp_vtptr(c##_Kind); 192 193 #define DECLARE_CLONED_VTABLE_KIND(c) c ## _Kind, 194 195 enum ClonedVtableKind { 196 // E.g., ConstantPool_Kind == 0, InstanceKlass_Kind == 1, etc. 197 CPP_VTABLE_TYPES_DO(DECLARE_CLONED_VTABLE_KIND) 198 _num_cloned_vtable_kinds 199 }; 200 201 // This is a map of all the original vtptrs. E.g., for 202 // ConstantPool *cp = new (...) ConstantPool(...) ; // a dynamically allocated constant pool 203 // the following holds true: 204 // _orig_cpp_vtptrs[ConstantPool_Kind] == ((intptr_t**)cp)[0] 205 static intptr_t* _orig_cpp_vtptrs[_num_cloned_vtable_kinds]; 206 static bool _orig_cpp_vtptrs_inited = false; 207 208 template <class T> 209 void CppVtableCloner<T>::init_orig_cpp_vtptr(int kind) { 210 assert(kind < _num_cloned_vtable_kinds, "sanity"); 211 T tmp; // Allocate temporary dummy metadata object to get to the original vtable. 212 intptr_t* srcvtable = vtable_of(&tmp); 213 _orig_cpp_vtptrs[kind] = srcvtable; 214 } 215 216 // This is the index of all the cloned vtables. E.g., for 217 // ConstantPool* cp = ....; // an archived constant pool 218 // InstanceKlass* ik = ....;// an archived class 219 // the following holds true: 220 // _index[ConstantPool_Kind]->cloned_vtable() == ((intptr_t**)cp)[0] 221 // _index[InstanceKlass_Kind]->cloned_vtable() == ((intptr_t**)ik)[0] 222 CppVtableInfo** CppVtables::_index = nullptr; 223 224 char* CppVtables::dumptime_init(ArchiveBuilder* builder) { 225 assert(CDSConfig::is_dumping_static_archive(), "cpp tables are only dumped into static archive"); 226 size_t vtptrs_bytes = _num_cloned_vtable_kinds * sizeof(CppVtableInfo*); 227 _index = (CppVtableInfo**)builder->rw_region()->allocate(vtptrs_bytes); 228 229 CPP_VTABLE_TYPES_DO(ALLOCATE_AND_INITIALIZE_VTABLE); 230 231 size_t cpp_tables_size = builder->rw_region()->top() - builder->rw_region()->base(); 232 builder->alloc_stats()->record_cpp_vtables((int)cpp_tables_size); 233 234 return (char*)_index; 235 } 236 237 void CppVtables::serialize(SerializeClosure* soc) { 238 soc->do_ptr(&_index); 239 if (soc->reading()) { 240 CPP_VTABLE_TYPES_DO(INITIALIZE_VTABLE); 241 } 242 } 243 244 intptr_t* CppVtables::get_archived_vtable(MetaspaceObj::Type msotype, address obj) { 245 if (!_orig_cpp_vtptrs_inited) { 246 CPP_VTABLE_TYPES_DO(INIT_ORIG_CPP_VTPTRS); 247 _orig_cpp_vtptrs_inited = true; 248 } 249 250 assert(CDSConfig::is_dumping_archive(), "sanity"); 251 int kind = -1; 252 switch (msotype) { 253 case MetaspaceObj::SymbolType: 254 case MetaspaceObj::TypeArrayU1Type: 255 case MetaspaceObj::TypeArrayU2Type: 256 case MetaspaceObj::TypeArrayU4Type: 257 case MetaspaceObj::TypeArrayU8Type: 258 case MetaspaceObj::TypeArrayOtherType: 259 case MetaspaceObj::ConstMethodType: 260 case MetaspaceObj::ConstantPoolCacheType: 261 case MetaspaceObj::AnnotationsType: 262 case MetaspaceObj::MethodCountersType: 263 case MetaspaceObj::SharedClassPathEntryType: 264 case MetaspaceObj::RecordComponentType: 265 // These have no vtables. 266 break; 267 case MetaspaceObj::MethodDataType: 268 // We don't archive MethodData <-- should have been removed in removed_unsharable_info 269 ShouldNotReachHere(); 270 break; 271 default: 272 for (kind = 0; kind < _num_cloned_vtable_kinds; kind ++) { 273 if (vtable_of((Metadata*)obj) == _orig_cpp_vtptrs[kind]) { 274 break; 275 } 276 } 277 if (kind >= _num_cloned_vtable_kinds) { 278 fatal("Cannot find C++ vtable for " INTPTR_FORMAT " -- you probably added" 279 " a new subtype of Klass or MetaData without updating CPP_VTABLE_TYPES_DO or the cases in this 'switch' statement", 280 p2i(obj)); 281 } 282 } 283 284 if (kind >= 0) { 285 assert(kind < _num_cloned_vtable_kinds, "must be"); 286 return _index[kind]->cloned_vtable(); 287 } else { 288 return nullptr; 289 } 290 } 291 292 void CppVtables::zero_archived_vtables() { 293 assert(CDSConfig::is_dumping_static_archive(), "cpp tables are only dumped into static archive"); 294 for (int kind = 0; kind < _num_cloned_vtable_kinds; kind ++) { 295 _index[kind]->zero(); 296 } 297 } 298 299 bool CppVtables::is_valid_shared_method(const Method* m) { 300 assert(MetaspaceShared::is_in_shared_metaspace(m), "must be"); 301 return vtable_of(m) == _index[Method_Kind]->cloned_vtable(); 302 }