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.
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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 inline uint VtableStubs::unsafe_hash(address entry_point) {
259 // The entrypoint may or may not be a VtableStub. Generate a hash as if it was.
260 address vtable_stub_addr = entry_point - VtableStub::entry_offset();
261 assert(CodeCache::contains(vtable_stub_addr), "assumed to always be the case");
262 address vtable_type_addr = vtable_stub_addr + offset_of(VtableStub, _type);
263 address vtable_index_addr = vtable_stub_addr + offset_of(VtableStub, _index);
264 bool is_vtable_stub = *vtable_type_addr == static_cast<uint8_t>(VtableStub::Type::vtable_stub);
265 short vtable_index;
266 static_assert(sizeof(VtableStub::_index) == sizeof(vtable_index), "precondition");
267 memcpy(&vtable_index, vtable_index_addr, sizeof(vtable_index));
268 return hash(is_vtable_stub, vtable_index);
269 }
270
271
272 VtableStub* VtableStubs::lookup(bool is_vtable_stub, int vtable_index) {
273 assert_lock_strong(VtableStubs_lock);
274 unsigned hash = VtableStubs::hash(is_vtable_stub, vtable_index);
275 VtableStub* s = Atomic::load(&_table[hash]);
276 while( s && !s->matches(is_vtable_stub, vtable_index)) s = s->next();
277 return s;
278 }
279
280
281 void VtableStubs::enter(bool is_vtable_stub, int vtable_index, VtableStub* s) {
282 assert_lock_strong(VtableStubs_lock);
283 assert(s->matches(is_vtable_stub, vtable_index), "bad vtable stub");
284 unsigned int h = VtableStubs::hash(is_vtable_stub, vtable_index);
285 // Insert s at the beginning of the corresponding list.
286 s->set_next(Atomic::load(&_table[h]));
287 // Make sure that concurrent readers not taking the mutex observe the writing of "next".
288 Atomic::release_store(&_table[h], s);
289 }
290
291 VtableStub* VtableStubs::entry_point(address pc) {
292 // The pc may or may not be the entry point for a VtableStub. Use unsafe_hash
293 // to generate the hash that would have been used if it was. The lookup in the
294 // _table will only succeed if there is a VtableStub with an entry point at
295 // the pc.
296 MutexLocker ml(VtableStubs_lock, Mutex::_no_safepoint_check_flag);
297 uint hash = VtableStubs::unsafe_hash(pc);
298 VtableStub* s;
299 for (s = Atomic::load(&_table[hash]); s != nullptr && s->entry_point() != pc; s = s->next()) {}
300 return (s != nullptr && s->entry_point() == pc) ? s : nullptr;
301 }
302
303 bool VtableStubs::contains(address pc) {
304 // simple solution for now - we may want to use
305 // a faster way if this function is called often
306 return stub_containing(pc) != nullptr;
307 }
308
309
310 VtableStub* VtableStubs::stub_containing(address pc) {
311 for (int i = 0; i < N; i++) {
312 for (VtableStub* s = Atomic::load_acquire(&_table[i]); s != nullptr; s = s->next()) {
313 if (s->contains(pc)) return s;
314 }
315 }
316 return nullptr;
317 }
318
319 void vtableStubs_init() {
320 VtableStubs::initialize();
321 }
322
323 void VtableStubs::vtable_stub_do(void f(VtableStub*)) {
324 for (int i = 0; i < N; i++) {
325 for (VtableStub* s = Atomic::load_acquire(&_table[i]); s != nullptr; s = s->next()) {
326 f(s);
327 }
328 }
329 }
330
331
332 //-----------------------------------------------------------------------------------------------------
333 // Non-product code
334 #ifndef PRODUCT
335
336 extern "C" void bad_compiled_vtable_index(JavaThread* thread, oop receiver, int index) {
337 ResourceMark rm;
338 Klass* klass = receiver->klass();
339 InstanceKlass* ik = InstanceKlass::cast(klass);
340 klassVtable vt = ik->vtable();
341 ik->print();
342 fatal("bad compiled vtable dispatch: receiver " INTPTR_FORMAT ", "
343 "index %d (vtable length %d)",
344 p2i(receiver), index, vt.length());
345 }
346
347 #endif // PRODUCT