1 /*
  2  * Copyright (c) 1997, 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.
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 23  */
 24 
 25 #include "precompiled.hpp"
 26 #include "code/vtableStubs.hpp"
 27 #include "compiler/compileBroker.hpp"
 28 #include "compiler/disassembler.hpp"
 29 #include "logging/log.hpp"
 30 #include "memory/allocation.inline.hpp"
 31 #include "memory/resourceArea.hpp"
 32 #include "oops/instanceKlass.hpp"
 33 #include "oops/klass.inline.hpp"
 34 #include "oops/klassVtable.hpp"
 35 #include "oops/oop.inline.hpp"
 36 #include "prims/forte.hpp"
 37 #include "prims/jvmtiExport.hpp"
 38 #include "runtime/handles.inline.hpp"
 39 #include "runtime/mutexLocker.hpp"
 40 #include "runtime/sharedRuntime.hpp"
 41 #include "utilities/align.hpp"
 42 #include "utilities/powerOfTwo.hpp"
 43 #ifdef COMPILER2
 44 #include "opto/matcher.hpp"
 45 #endif
 46 
 47 // -----------------------------------------------------------------------------------------
 48 // Implementation of VtableStub
 49 
 50 address VtableStub::_chunk             = nullptr;
 51 address VtableStub::_chunk_end         = nullptr;
 52 VMReg   VtableStub::_receiver_location = VMRegImpl::Bad();
 53 
 54 
 55 void* VtableStub::operator new(size_t size, int code_size) throw() {
 56   assert_lock_strong(VtableStubs_lock);
 57   assert(size == sizeof(VtableStub), "mismatched size");
 58   // compute real VtableStub size (rounded to nearest word)
 59   const int real_size = align_up(code_size + (int)sizeof(VtableStub), wordSize);
 60   // malloc them in chunks to minimize header overhead
 61   const int chunk_factor = 32;
 62   if (_chunk == nullptr || _chunk + real_size > _chunk_end) {
 63     const int bytes = chunk_factor * real_size + pd_code_alignment();
 64 
 65    // There is a dependency on the name of the blob in src/share/vm/prims/jvmtiCodeBlobEvents.cpp
 66    // If changing the name, update the other file accordingly.
 67     VtableBlob* blob = VtableBlob::create("vtable chunks", bytes);
 68     if (blob == nullptr) {
 69       return nullptr;
 70     }
 71     _chunk = blob->content_begin();
 72     _chunk_end = _chunk + bytes;
 73     Forte::register_stub("vtable stub", _chunk, _chunk_end);
 74     align_chunk();
 75   }
 76   assert(_chunk + real_size <= _chunk_end, "bad allocation");
 77   void* res = _chunk;
 78   _chunk += real_size;
 79   align_chunk();
 80  return res;
 81 }
 82 
 83 
 84 void VtableStub::print_on(outputStream* st) const {
 85   st->print("vtable stub (index = %d, receiver_location = " INTX_FORMAT ", code = [" INTPTR_FORMAT ", " INTPTR_FORMAT "])",
 86              index(), p2i(receiver_location()), p2i(code_begin()), p2i(code_end()));
 87 }
 88 
 89 void VtableStub::print() const { print_on(tty); }
 90 
 91 // -----------------------------------------------------------------------------------------
 92 // Implementation of VtableStubs
 93 //
 94 // For each hash value there's a linked list of vtable stubs (with that
 95 // hash value). Each list is anchored in a little hash _table, indexed
 96 // by that hash value.
 97 
 98 VtableStub* volatile VtableStubs::_table[VtableStubs::N];
 99 int VtableStubs::_vtab_stub_size = 0;
100 int VtableStubs::_itab_stub_size = 0;
101 
102 #if defined(PRODUCT)
103   // These values are good for the PRODUCT case (no tracing).
104   static const int first_vtableStub_size =  64;
105   static const int first_itableStub_size = 256;
106 #else
107   // These values are good for the non-PRODUCT case (when tracing can be switched on).
108   // To find out, run test workload with
109   //   -Xlog:vtablestubs=Trace -XX:+CountCompiledCalls -XX:+DebugVtables
110   // and use the reported "estimate" value.
111   // Here is a list of observed worst-case values:
112   //               vtable  itable
113   // aarch64:         460     324
114   // arm:               ?       ?
115   // ppc (linux, BE): 404     288
116   // ppc (linux, LE): 356     276
117   // ppc (AIX):       416     296
118   // s390x:           408     256
119   // Solaris-sparc:   792     348
120   // x86 (Linux):     670     309
121   // x86 (MacOS):     682     321
122   static const int first_vtableStub_size = 1024;
123   static const int first_itableStub_size =  512;
124 #endif
125 
126 
127 void VtableStubs::initialize() {
128   assert(VtableStub::_receiver_location == VMRegImpl::Bad(), "initialized multiple times?");
129 
130   VtableStub::_receiver_location = SharedRuntime::name_for_receiver();
131   {
132     MutexLocker ml(VtableStubs_lock, Mutex::_no_safepoint_check_flag);
133     for (int i = 0; i < N; i++) {
134       Atomic::store(&_table[i], (VtableStub*)nullptr);
135     }
136   }
137 }
138 
139 
140 int VtableStubs::code_size_limit(bool is_vtable_stub) {
141   if (is_vtable_stub) {
142     return _vtab_stub_size > 0 ? _vtab_stub_size : first_vtableStub_size;
143   } else { // itable stub
144     return _itab_stub_size > 0 ? _itab_stub_size : first_itableStub_size;
145   }
146 }   // code_size_limit
147 
148 
149 void VtableStubs::check_and_set_size_limit(bool is_vtable_stub,
150                                            int  code_size,
151                                            int  padding) {
152   const char* name = is_vtable_stub ? "vtable" : "itable";
153 
154   guarantee(code_size <= code_size_limit(is_vtable_stub),
155             "buffer overflow in %s stub, code_size is %d, limit is %d", name, code_size, code_size_limit(is_vtable_stub));
156 
157   if (is_vtable_stub) {
158     if (log_is_enabled(Trace, vtablestubs)) {
159       if ( (_vtab_stub_size > 0) && ((code_size + padding) > _vtab_stub_size) ) {
160         log_trace(vtablestubs)("%s size estimate needed adjustment from %d to %d bytes",
161                                name, _vtab_stub_size, code_size + padding);
162       }
163     }
164     if ( (code_size + padding) > _vtab_stub_size ) {
165       _vtab_stub_size = code_size + padding;
166     }
167   } else {  // itable stub
168     if (log_is_enabled(Trace, vtablestubs)) {
169       if ( (_itab_stub_size > 0) && ((code_size + padding) > _itab_stub_size) ) {
170         log_trace(vtablestubs)("%s size estimate needed adjustment from %d to %d bytes",
171                                name, _itab_stub_size, code_size + padding);
172       }
173     }
174     if ( (code_size + padding) > _itab_stub_size ) {
175       _itab_stub_size = code_size + padding;
176     }
177   }
178   return;
179 }   // check_and_set_size_limit
180 
181 
182 void VtableStubs::bookkeeping(MacroAssembler* masm, outputStream* out, VtableStub* s,
183                               address npe_addr, address ame_addr,   bool is_vtable_stub,
184                               int     index,    int     slop_bytes, int  index_dependent_slop) {
185   const char* name        = is_vtable_stub ? "vtable" : "itable";
186   const int   stub_length = code_size_limit(is_vtable_stub);
187 
188   if (log_is_enabled(Trace, vtablestubs)) {
189     log_trace(vtablestubs)("%s #%d at " PTR_FORMAT ": size: %d, estimate: %d, slop area: %d",
190                            name, index, p2i(s->code_begin()),
191                            (int)(masm->pc() - s->code_begin()),
192                            stub_length,
193                            (int)(s->code_end() - masm->pc()));
194   }
195   guarantee(masm->pc() <= s->code_end(), "%s #%d: overflowed buffer, estimated len: %d, actual len: %d, overrun: %d",
196                                          name, index, stub_length,
197                                          (int)(masm->pc() - s->code_begin()),
198                                          (int)(masm->pc() - s->code_end()));
199   assert((masm->pc() + index_dependent_slop) <= s->code_end(), "%s #%d: spare space for 32-bit offset: required = %d, available = %d",
200                                          name, index, index_dependent_slop,
201                                          (int)(s->code_end() - masm->pc()));
202 
203   // After the first vtable/itable stub is generated, we have a much
204   // better estimate for the stub size. Remember/update this
205   // estimate after some sanity checks.
206   check_and_set_size_limit(is_vtable_stub, masm->offset(), slop_bytes);
207   s->set_exception_points(npe_addr, ame_addr);
208 }
209 
210 
211 address VtableStubs::find_stub(bool is_vtable_stub, int vtable_index) {
212   assert(vtable_index >= 0, "must be positive");
213 
214   VtableStub* s;
215   {
216     MutexLocker ml(VtableStubs_lock, Mutex::_no_safepoint_check_flag);
217     s = lookup(is_vtable_stub, vtable_index);
218     if (s == nullptr) {
219       if (is_vtable_stub) {
220         s = create_vtable_stub(vtable_index);
221       } else {
222         s = create_itable_stub(vtable_index);
223       }
224 
225       // Creation of vtable or itable can fail if there is not enough free space in the code cache.
226       if (s == nullptr) {
227         return nullptr;
228       }
229 
230       enter(is_vtable_stub, vtable_index, s);
231       if (PrintAdapterHandlers) {
232         tty->print_cr("Decoding VtableStub %s[%d]@" PTR_FORMAT " [" PTR_FORMAT ", " PTR_FORMAT "] (" SIZE_FORMAT " bytes)",
233                       is_vtable_stub? "vtbl": "itbl", vtable_index, p2i(VtableStub::receiver_location()),
234                       p2i(s->code_begin()), p2i(s->code_end()), pointer_delta(s->code_end(), s->code_begin(), 1));
235         Disassembler::decode(s->code_begin(), s->code_end());
236       }
237       // Notify JVMTI about this stub. The event will be recorded by the enclosing
238       // JvmtiDynamicCodeEventCollector and posted when this thread has released
239       // all locks. Only post this event if a new state is not required. Creating a new state would
240       // cause a safepoint and the caller of this code has a NoSafepointVerifier.
241       if (JvmtiExport::should_post_dynamic_code_generated()) {
242         JvmtiExport::post_dynamic_code_generated_while_holding_locks(is_vtable_stub? "vtable stub": "itable stub",
243                                                                      s->code_begin(), s->code_end());
244       }
245     }
246   }
247   return s->entry_point();
248 }
249 
250 
251 inline uint VtableStubs::hash(bool is_vtable_stub, int vtable_index){
252   // Assumption: receiver_location < 4 in most cases.
253   int hash = ((vtable_index << 2) ^ VtableStub::receiver_location()->value()) + vtable_index;
254   return (is_vtable_stub ? ~hash : hash)  & mask;
255 }
256 
257 
258 VtableStub* VtableStubs::lookup(bool is_vtable_stub, int vtable_index) {
259   assert_lock_strong(VtableStubs_lock);
260   unsigned hash = VtableStubs::hash(is_vtable_stub, vtable_index);
261   VtableStub* s = Atomic::load(&_table[hash]);
262   while( s && !s->matches(is_vtable_stub, vtable_index)) s = s->next();
263   return s;
264 }
265 
266 
267 void VtableStubs::enter(bool is_vtable_stub, int vtable_index, VtableStub* s) {
268   assert_lock_strong(VtableStubs_lock);
269   assert(s->matches(is_vtable_stub, vtable_index), "bad vtable stub");
270   unsigned int h = VtableStubs::hash(is_vtable_stub, vtable_index);
271   // Insert s at the beginning of the corresponding list.
272   s->set_next(Atomic::load(&_table[h]));
273   // Make sure that concurrent readers not taking the mutex observe the writing of "next".
274   Atomic::release_store(&_table[h], s);
275 }
276 
277 VtableStub* VtableStubs::entry_point(address pc) {
278   MutexLocker ml(VtableStubs_lock, Mutex::_no_safepoint_check_flag);
279   VtableStub* stub = (VtableStub*)(pc - VtableStub::entry_offset());
280   uint hash = VtableStubs::hash(stub->is_vtable_stub(), stub->index());
281   VtableStub* s;
282   for (s = Atomic::load(&_table[hash]); s != nullptr && s != stub; s = s->next()) {}
283   return (s == stub) ? s : nullptr;
284 }
285 
286 bool VtableStubs::contains(address pc) {
287   // simple solution for now - we may want to use
288   // a faster way if this function is called often
289   return stub_containing(pc) != nullptr;
290 }
291 
292 
293 VtableStub* VtableStubs::stub_containing(address pc) {
294   for (int i = 0; i < N; i++) {
295     for (VtableStub* s = Atomic::load_acquire(&_table[i]); s != nullptr; s = s->next()) {
296       if (s->contains(pc)) return s;
297     }
298   }
299   return nullptr;
300 }
301 
302 void vtableStubs_init() {
303   VtableStubs::initialize();
304 }
305 
306 void VtableStubs::vtable_stub_do(void f(VtableStub*)) {
307   for (int i = 0; i < N; i++) {
308     for (VtableStub* s = Atomic::load_acquire(&_table[i]); s != nullptr; s = s->next()) {
309       f(s);
310     }
311   }
312 }
313 
314 
315 //-----------------------------------------------------------------------------------------------------
316 // Non-product code
317 #ifndef PRODUCT
318 
319 extern "C" void bad_compiled_vtable_index(JavaThread* thread, oop receiver, int index) {
320   ResourceMark rm;
321   Klass* klass = receiver->klass();
322   InstanceKlass* ik = InstanceKlass::cast(klass);
323   klassVtable vt = ik->vtable();
324   ik->print();
325   fatal("bad compiled vtable dispatch: receiver " INTPTR_FORMAT ", "
326         "index %d (vtable length %d)",
327         p2i(receiver), index, vt.length());
328 }
329 
330 #endif // PRODUCT