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/instanceClassLoaderKlass.hpp" 33 #include "oops/instanceMirrorKlass.hpp" 34 #include "oops/instanceRefKlass.hpp" 35 #include "oops/instanceStackChunkKlass.hpp" 36 #include "oops/methodCounters.hpp" 37 #include "oops/methodData.hpp" 38 #include "oops/trainingData.hpp" 39 #include "oops/objArrayKlass.hpp" 40 #include "oops/typeArrayKlass.hpp" 41 #include "runtime/arguments.hpp" 42 #include "utilities/globalDefinitions.hpp" 43 44 // Objects of the Metadata types (such as Klass and ConstantPool) have C++ vtables. 45 // (In GCC this is the field <Type>::_vptr, i.e., first word in the object.) 46 // 47 // Addresses of the vtables and the methods may be different across JVM runs, 48 // if libjvm.so is dynamically loaded at a different base address. 49 // 50 // To ensure that the Metadata objects in the CDS archive always have the correct vtable: 51 // 52 // + at dump time: we redirect the _vptr to point to our own vtables inside 53 // the CDS image 54 // + at run time: we clone the actual contents of the vtables from libjvm.so 55 // into our own tables. 56 57 // Currently, the archive contains ONLY the following types of objects that have C++ vtables. 58 #define CPP_VTABLE_TYPES_DO(f) \ 59 f(ConstantPool) \ 60 f(InstanceKlass) \ 61 f(InstanceClassLoaderKlass) \ 62 f(InstanceMirrorKlass) \ 63 f(InstanceRefKlass) \ 64 f(InstanceStackChunkKlass) \ 65 f(Method) \ 66 f(MethodData) \ 67 f(MethodCounters) \ 68 f(ObjArrayKlass) \ 69 f(TypeArrayKlass) \ 70 f(KlassTrainingData) \ 71 f(MethodTrainingData) \ 72 f(CompileTrainingData) 73 74 class CppVtableInfo { 75 intptr_t _vtable_size; 76 intptr_t _cloned_vtable[1]; 77 public: 78 static int num_slots(int vtable_size) { 79 return 1 + vtable_size; // Need to add the space occupied by _vtable_size; 80 } 81 int vtable_size() { return int(uintx(_vtable_size)); } 82 void set_vtable_size(int n) { _vtable_size = intptr_t(n); } 83 intptr_t* cloned_vtable() { return &_cloned_vtable[0]; } 84 void zero() { memset(_cloned_vtable, 0, sizeof(intptr_t) * vtable_size()); } 85 // Returns the address of the next CppVtableInfo that can be placed immediately after this CppVtableInfo 86 static size_t byte_size(int vtable_size) { 87 CppVtableInfo i; 88 return pointer_delta(&i._cloned_vtable[vtable_size], &i, sizeof(u1)); 89 } 90 }; 91 92 static inline intptr_t* vtable_of(const Metadata* m) { 93 return *((intptr_t**)m); 94 } 95 96 template <class T> class CppVtableCloner { 97 static int get_vtable_length(const char* name); 98 99 public: 100 // Allocate a clone of the vtable of T from the shared metaspace; 101 // Initialize the contents of this clone. 102 static CppVtableInfo* allocate_and_initialize(const char* name); 103 104 // Copy the contents of the vtable of T into info->_cloned_vtable; 105 static void initialize(const char* name, CppVtableInfo* info); 106 107 static void init_orig_cpp_vtptr(int kind); 108 }; 109 110 template <class T> 111 CppVtableInfo* CppVtableCloner<T>::allocate_and_initialize(const char* name) { 112 int n = get_vtable_length(name); 113 CppVtableInfo* info = 114 (CppVtableInfo*)ArchiveBuilder::current()->rw_region()->allocate(CppVtableInfo::byte_size(n)); 115 info->set_vtable_size(n); 116 initialize(name, info); 117 return info; 118 } 119 120 template <class T> 121 void CppVtableCloner<T>::initialize(const char* name, CppVtableInfo* info) { 122 T tmp; // Allocate temporary dummy metadata object to get to the original vtable. 123 int n = info->vtable_size(); 124 intptr_t* srcvtable = vtable_of(&tmp); 125 intptr_t* dstvtable = info->cloned_vtable(); 126 127 // We already checked (and, if necessary, adjusted n) when the vtables were allocated, so we are 128 // safe to do memcpy. 129 log_debug(cds, vtables)("Copying %3d vtable entries for %s", n, name); 130 memcpy(dstvtable, srcvtable, sizeof(intptr_t) * n); 131 } 132 133 // To determine the size of the vtable for each type, we use the following 134 // trick by declaring 2 subclasses: 135 // 136 // class CppVtableTesterA: public InstanceKlass {virtual int last_virtual_method() {return 1;} }; 137 // class CppVtableTesterB: public InstanceKlass {virtual void* last_virtual_method() {return nullptr}; }; 138 // 139 // CppVtableTesterA and CppVtableTesterB's vtables have the following properties: 140 // - Their size (N+1) is exactly one more than the size of InstanceKlass's vtable (N) 141 // - The first N entries have are exactly the same as in InstanceKlass's vtable. 142 // - Their last entry is different. 143 // 144 // So to determine the value of N, we just walk CppVtableTesterA and CppVtableTesterB's tables 145 // and find the first entry that's different. 146 // 147 // This works on all C++ compilers supported by Oracle, but you may need to tweak it for more 148 // esoteric compilers. 149 150 template <class T> class CppVtableTesterB: public T { 151 public: 152 virtual int last_virtual_method() {return 1;} 153 }; 154 155 template <class T> class CppVtableTesterA : public T { 156 public: 157 virtual void* last_virtual_method() { 158 // Make this different than CppVtableTesterB::last_virtual_method so the C++ 159 // compiler/linker won't alias the two functions. 160 return nullptr; 161 } 162 }; 163 164 template <class T> 165 int CppVtableCloner<T>::get_vtable_length(const char* name) { 166 CppVtableTesterA<T> a; 167 CppVtableTesterB<T> b; 168 169 intptr_t* avtable = vtable_of(&a); 170 intptr_t* bvtable = vtable_of(&b); 171 172 // Start at slot 1, because slot 0 may be RTTI (on Solaris/Sparc) 173 int vtable_len = 1; 174 for (; ; vtable_len++) { 175 if (avtable[vtable_len] != bvtable[vtable_len]) { 176 break; 177 } 178 } 179 log_debug(cds, vtables)("Found %3d vtable entries for %s", vtable_len, name); 180 181 return vtable_len; 182 } 183 184 #define ALLOCATE_AND_INITIALIZE_VTABLE(c) \ 185 _index[c##_Kind] = CppVtableCloner<c>::allocate_and_initialize(#c); \ 186 ArchivePtrMarker::mark_pointer(&_index[c##_Kind]); 187 188 #define INITIALIZE_VTABLE(c) \ 189 CppVtableCloner<c>::initialize(#c, _index[c##_Kind]); 190 191 #define INIT_ORIG_CPP_VTPTRS(c) \ 192 CppVtableCloner<c>::init_orig_cpp_vtptr(c##_Kind); 193 194 #define DECLARE_CLONED_VTABLE_KIND(c) c ## _Kind, 195 196 enum ClonedVtableKind { 197 // E.g., ConstantPool_Kind == 0, InstanceKlass_Kind == 1, etc. 198 CPP_VTABLE_TYPES_DO(DECLARE_CLONED_VTABLE_KIND) 199 _num_cloned_vtable_kinds 200 }; 201 202 // This is a map of all the original vtptrs. E.g., for 203 // ConstantPool *cp = new (...) ConstantPool(...) ; // a dynamically allocated constant pool 204 // the following holds true: 205 // _orig_cpp_vtptrs[ConstantPool_Kind] == ((intptr_t**)cp)[0] 206 static intptr_t* _orig_cpp_vtptrs[_num_cloned_vtable_kinds]; // vtptrs set by the C++ compiler 207 static intptr_t* _archived_cpp_vtptrs[_num_cloned_vtable_kinds]; // vtptrs used in the static archive 208 static bool _orig_cpp_vtptrs_inited = false; 209 210 template <class T> 211 void CppVtableCloner<T>::init_orig_cpp_vtptr(int kind) { 212 assert(kind < _num_cloned_vtable_kinds, "sanity"); 213 T tmp; // Allocate temporary dummy metadata object to get to the original vtable. 214 intptr_t* srcvtable = vtable_of(&tmp); 215 _orig_cpp_vtptrs[kind] = srcvtable; 216 } 217 218 // This is the index of all the cloned vtables. E.g., for 219 // ConstantPool* cp = ....; // an archived constant pool 220 // InstanceKlass* ik = ....;// an archived class 221 // the following holds true: 222 // _index[ConstantPool_Kind]->cloned_vtable() == ((intptr_t**)cp)[0] 223 // _index[InstanceKlass_Kind]->cloned_vtable() == ((intptr_t**)ik)[0] 224 static CppVtableInfo* _index[_num_cloned_vtable_kinds]; 225 226 // Vtables are all fixed offsets from ArchiveBuilder::current()->mapped_base() 227 // E.g. ConstantPool is at offset 0x58. We can archive these offsets in the 228 // RO region and use them to alculate their location at runtime without storing 229 // the pointers in the RW region 230 char* CppVtables::_vtables_serialized_base = nullptr; 231 232 void CppVtables::dumptime_init(ArchiveBuilder* builder) { 233 assert(CDSConfig::is_dumping_static_archive(), "cpp tables are only dumped into static archive"); 234 235 CPP_VTABLE_TYPES_DO(ALLOCATE_AND_INITIALIZE_VTABLE); 236 237 if (!CDSConfig::is_dumping_final_static_archive()) { 238 for (int kind = 0; kind < _num_cloned_vtable_kinds; kind++) { 239 _archived_cpp_vtptrs[kind] = _index[kind]->cloned_vtable(); 240 } 241 } 242 243 size_t cpp_tables_size = builder->rw_region()->top() - builder->rw_region()->base(); 244 builder->alloc_stats()->record_cpp_vtables((int)cpp_tables_size); 245 } 246 247 void CppVtables::serialize(SerializeClosure* soc) { 248 if (!soc->reading()) { 249 _vtables_serialized_base = (char*)ArchiveBuilder::current()->buffer_top(); 250 } 251 for (int i = 0; i < _num_cloned_vtable_kinds; i++) { 252 soc->do_ptr(&_index[i]); 253 } 254 if (soc->reading()) { 255 CPP_VTABLE_TYPES_DO(INITIALIZE_VTABLE); 256 } 257 258 if (soc->writing() && CDSConfig::is_dumping_final_static_archive()) { 259 memset(_archived_cpp_vtptrs, 0, sizeof(_archived_cpp_vtptrs)); 260 } 261 262 for (int kind = 0; kind < _num_cloned_vtable_kinds; kind++) { 263 soc->do_ptr(&_archived_cpp_vtptrs[kind]); 264 } 265 } 266 267 intptr_t* CppVtables::get_archived_vtable(MetaspaceObj::Type msotype, address obj) { 268 if (!_orig_cpp_vtptrs_inited) { 269 CPP_VTABLE_TYPES_DO(INIT_ORIG_CPP_VTPTRS); 270 _orig_cpp_vtptrs_inited = true; 271 } 272 273 assert(CDSConfig::is_dumping_archive(), "sanity"); 274 int kind = -1; 275 switch (msotype) { 276 case MetaspaceObj::SymbolType: 277 case MetaspaceObj::TypeArrayU1Type: 278 case MetaspaceObj::TypeArrayU2Type: 279 case MetaspaceObj::TypeArrayU4Type: 280 case MetaspaceObj::TypeArrayU8Type: 281 case MetaspaceObj::TypeArrayOtherType: 282 case MetaspaceObj::ConstMethodType: 283 case MetaspaceObj::ConstantPoolCacheType: 284 case MetaspaceObj::AnnotationsType: 285 case MetaspaceObj::SharedClassPathEntryType: 286 case MetaspaceObj::RecordComponentType: 287 // These have no vtables. 288 break; 289 default: 290 for (kind = 0; kind < _num_cloned_vtable_kinds; kind ++) { 291 if (vtable_of((Metadata*)obj) == _orig_cpp_vtptrs[kind] || 292 vtable_of((Metadata*)obj) == _archived_cpp_vtptrs[kind]) { 293 break; 294 } 295 } 296 if (kind >= _num_cloned_vtable_kinds) { 297 fatal("Cannot find C++ vtable for " INTPTR_FORMAT " -- you probably added" 298 " a new subtype of Klass or MetaData without updating CPP_VTABLE_TYPES_DO or the cases in this 'switch' statement", 299 p2i(obj)); 300 } 301 } 302 303 if (kind >= 0) { 304 assert(kind < _num_cloned_vtable_kinds, "must be"); 305 return _index[kind]->cloned_vtable(); 306 } else { 307 return nullptr; 308 } 309 } 310 311 void CppVtables::zero_archived_vtables() { 312 assert(CDSConfig::is_dumping_static_archive(), "cpp tables are only dumped into static archive"); 313 for (int kind = 0; kind < _num_cloned_vtable_kinds; kind ++) { 314 _index[kind]->zero(); 315 } 316 } 317 318 bool CppVtables::is_valid_shared_method(const Method* m) { 319 assert(MetaspaceShared::is_in_shared_metaspace(m), "must be"); 320 return vtable_of(m) == _index[Method_Kind]->cloned_vtable(); 321 }