1 /*
2 * Copyright (c) 2018, 2022, 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 "gc/shared/barrierSetNMethod.hpp"
27 #include "runtime/arguments.hpp"
28 #include "runtime/continuation.hpp"
29 #include "runtime/continuationEntry.inline.hpp"
30 #include "runtime/continuationHelper.inline.hpp"
31 #include "runtime/continuationJavaClasses.inline.hpp"
32 #include "runtime/continuationWrapper.inline.hpp"
33 #include "runtime/interfaceSupport.inline.hpp"
34 #include "runtime/javaThread.inline.hpp"
35 #include "runtime/osThread.hpp"
36 #include "runtime/vframe.inline.hpp"
37 #include "runtime/vframe_hp.hpp"
38
39 // defined in continuationFreezeThaw.cpp
40 extern "C" jint JNICALL CONT_isPinned0(JNIEnv* env, jobject cont_scope);
41
42 JVM_ENTRY(void, CONT_pin(JNIEnv* env, jclass cls)) {
43 if (!Continuation::pin(JavaThread::thread_from_jni_environment(env))) {
44 THROW_MSG(vmSymbols::java_lang_IllegalStateException(), "pin overflow");
45 }
46 }
47 JVM_END
48
49 JVM_ENTRY(void, CONT_unpin(JNIEnv* env, jclass cls)) {
50 if (!Continuation::unpin(JavaThread::thread_from_jni_environment(env))) {
51 THROW_MSG(vmSymbols::java_lang_IllegalStateException(), "pin underflow");
52 }
53 }
54 JVM_END
55
56 #ifndef PRODUCT
57 static jlong java_tid(JavaThread* thread) {
58 return java_lang_Thread::thread_id(thread->threadObj());
59 }
60 #endif
61
62 const ContinuationEntry* Continuation::last_continuation(const JavaThread* thread, oop cont_scope) {
63 // guarantee (thread->has_last_Java_frame(), "");
64 for (ContinuationEntry* entry = thread->last_continuation(); entry != nullptr; entry = entry->parent()) {
65 if (cont_scope == jdk_internal_vm_Continuation::scope(entry->cont_oop())) {
66 return entry;
67 }
68 }
69 return nullptr;
70 }
71
72 ContinuationEntry* Continuation::get_continuation_entry_for_continuation(JavaThread* thread, oop continuation) {
73 if (thread == nullptr || continuation == nullptr) {
74 return nullptr;
75 }
76
77 for (ContinuationEntry* entry = thread->last_continuation(); entry != nullptr; entry = entry->parent()) {
78 if (continuation == entry->cont_oop()) {
79 return entry;
80 }
81 }
82 return nullptr;
83 }
84
85 static bool is_on_stack(JavaThread* thread, const ContinuationEntry* entry) {
86 if (entry == nullptr) {
87 return false;
88 }
89
90 assert(thread->is_in_full_stack((address)entry), "");
91 return true;
92 // return false if called when transitioning to Java on return from freeze
93 // return !thread->has_last_Java_frame() || thread->last_Java_sp() < cont->entry_sp();
94 }
95
96 bool Continuation::is_continuation_mounted(JavaThread* thread, oop continuation) {
97 return is_on_stack(thread, get_continuation_entry_for_continuation(thread, continuation));
98 }
99
100 bool Continuation::is_continuation_scope_mounted(JavaThread* thread, oop cont_scope) {
101 return is_on_stack(thread, last_continuation(thread, cont_scope));
102 }
103
104 // When walking the virtual stack, this method returns true
105 // iff the frame is a thawed continuation frame whose
106 // caller is still frozen on the h-stack.
107 // The continuation object can be extracted from the thread.
108 bool Continuation::is_cont_barrier_frame(const frame& f) {
109 assert(f.is_interpreted_frame() || f.cb() != nullptr, "");
110 if (!Continuations::enabled()) return false;
111 return is_return_barrier_entry(f.is_interpreted_frame() ? ContinuationHelper::InterpretedFrame::return_pc(f)
112 : ContinuationHelper::CompiledFrame::return_pc(f));
113 }
114
115 bool Continuation::is_return_barrier_entry(const address pc) {
116 if (!Continuations::enabled()) return false;
117 return pc == StubRoutines::cont_returnBarrier();
118 }
119
120 bool Continuation::is_continuation_enterSpecial(const frame& f) {
121 if (f.cb() == nullptr || !f.cb()->is_compiled()) {
122 return false;
123 }
124 Method* m = f.cb()->as_compiled_method()->method();
125 return (m != nullptr && m->is_continuation_enter_intrinsic());
126 }
127
128 bool Continuation::is_continuation_entry_frame(const frame& f, const RegisterMap *map) {
129 // we can do this because the entry frame is never inlined
130 Method* m = (map != nullptr && map->in_cont() && f.is_interpreted_frame())
131 ? map->stack_chunk()->interpreter_frame_method(f)
132 : ContinuationHelper::Frame::frame_method(f);
133 return m != nullptr && m->intrinsic_id() == vmIntrinsics::_Continuation_enter;
134 }
135
136 static inline bool is_sp_in_continuation(const ContinuationEntry* entry, intptr_t* const sp) {
137 return entry->entry_sp() > sp;
138 }
139
140 bool Continuation::is_frame_in_continuation(const ContinuationEntry* entry, const frame& f) {
141 return is_sp_in_continuation(entry, f.unextended_sp());
142 }
143
144 ContinuationEntry* Continuation::get_continuation_entry_for_sp(JavaThread* thread, intptr_t* const sp) {
145 assert(thread != nullptr, "");
146 ContinuationEntry* entry = thread->last_continuation();
147 while (entry != nullptr && !is_sp_in_continuation(entry, sp)) {
148 entry = entry->parent();
149 }
150 return entry;
151 }
152
153 ContinuationEntry* Continuation::get_continuation_entry_for_entry_frame(JavaThread* thread, const frame& f) {
154 assert(is_continuation_enterSpecial(f), "");
155 ContinuationEntry* entry = (ContinuationEntry*)f.unextended_sp();
156 assert(entry == get_continuation_entry_for_sp(thread, f.sp()-2), "mismatched entry");
157 return entry;
158 }
159
160 bool Continuation::is_frame_in_continuation(JavaThread* thread, const frame& f) {
161 return f.is_heap_frame() || (get_continuation_entry_for_sp(thread, f.unextended_sp()) != nullptr);
162 }
163
164 static frame continuation_top_frame(const ContinuationWrapper& cont, RegisterMap* map) {
165 stackChunkOop chunk = cont.last_nonempty_chunk();
166 map->set_stack_chunk(chunk);
167 return chunk != nullptr ? chunk->top_frame(map) : frame();
168 }
169
170 bool Continuation::has_last_Java_frame(oop continuation, frame* frame, RegisterMap* map) {
171 ContinuationWrapper cont(continuation);
172 if (!cont.is_empty()) {
173 *frame = continuation_top_frame(cont, map);
174 return true;
175 } else {
176 return false;
177 }
178 }
179
180 frame Continuation::last_frame(oop continuation, RegisterMap *map) {
181 assert(map != nullptr, "a map must be given");
182 return continuation_top_frame(ContinuationWrapper(continuation), map);
183 }
184
185 frame Continuation::top_frame(const frame& callee, RegisterMap* map) {
186 assert(map != nullptr, "");
187 ContinuationEntry* ce = get_continuation_entry_for_sp(map->thread(), callee.sp());
188 assert(ce != nullptr, "");
189 oop continuation = ce->cont_oop();
190 ContinuationWrapper cont(continuation);
191 return continuation_top_frame(cont, map);
192 }
193
194 javaVFrame* Continuation::last_java_vframe(Handle continuation, RegisterMap *map) {
195 assert(map != nullptr, "a map must be given");
196 if (!ContinuationWrapper(continuation()).is_empty()) {
197 frame f = last_frame(continuation(), map);
198 for (vframe* vf = vframe::new_vframe(&f, map, nullptr); vf; vf = vf->sender()) {
199 if (vf->is_java_frame()) {
200 return javaVFrame::cast(vf);
201 }
202 }
203 }
204 return nullptr;
205 }
206
207 frame Continuation::continuation_parent_frame(RegisterMap* map) {
208 assert(map->in_cont(), "");
209 ContinuationWrapper cont(map);
210 assert(map->thread() != nullptr || !cont.is_mounted(), "");
211
212 log_develop_trace(continuations)("continuation_parent_frame");
213 if (map->update_map()) {
214 // we need to register the link address for the entry frame
215 if (cont.entry() != nullptr) {
216 cont.entry()->update_register_map(map);
217 } else {
218 map->clear();
219 }
220 }
221
222 if (!cont.is_mounted()) { // When we're walking an unmounted continuation and reached the end
223 oop parent = jdk_internal_vm_Continuation::parent(cont.continuation());
224 stackChunkOop chunk = parent != nullptr ? ContinuationWrapper(parent).last_nonempty_chunk() : nullptr;
225 if (chunk != nullptr) {
226 return chunk->top_frame(map);
227 }
228
229 map->set_stack_chunk(nullptr);
230 return frame();
231 }
232
233 map->set_stack_chunk(nullptr);
234
235 #if (defined(X86) || defined(AARCH64)) && !defined(ZERO)
236 frame sender(cont.entrySP(), cont.entryFP(), cont.entryPC());
237 #else
238 frame sender = frame();
239 Unimplemented();
240 #endif
241
242 return sender;
243 }
244
245 oop Continuation::continuation_scope(oop continuation) {
246 return continuation != nullptr ? jdk_internal_vm_Continuation::scope(continuation) : nullptr;
247 }
248
249 bool Continuation::is_scope_bottom(oop cont_scope, const frame& f, const RegisterMap* map) {
250 if (cont_scope == nullptr || !is_continuation_entry_frame(f, map)) {
251 return false;
252 }
253
254 oop continuation;
255 if (map->in_cont()) {
256 continuation = map->cont();
257 } else {
258 ContinuationEntry* ce = get_continuation_entry_for_sp(map->thread(), f.sp());
259 if (ce == nullptr) {
260 return false;
261 }
262 continuation = ce->cont_oop();
263 }
264 if (continuation == nullptr) {
265 return false;
266 }
267
268 oop sc = continuation_scope(continuation);
269 assert(sc != nullptr, "");
270 return sc == cont_scope;
271 }
272
273 bool Continuation::is_in_usable_stack(address addr, const RegisterMap* map) {
274 ContinuationWrapper cont(map);
275 stackChunkOop chunk = cont.find_chunk_by_address(addr);
276 return chunk != nullptr ? chunk->is_usable_in_chunk(addr) : false;
277 }
278
279 bool Continuation::pin(JavaThread* current) {
280 ContinuationEntry* ce = current->last_continuation();
281 if (ce == nullptr) {
282 return true; // no continuation mounted
283 }
284 return ce->pin();
285 }
286
287 bool Continuation::unpin(JavaThread* current) {
288 ContinuationEntry* ce = current->last_continuation();
289 if (ce == nullptr) {
290 return true; // no continuation mounted
291 }
292 return ce->unpin();
293 }
294
295 frame Continuation::continuation_bottom_sender(JavaThread* thread, const frame& callee, intptr_t* sender_sp) {
296 assert (thread != nullptr, "");
297 ContinuationEntry* ce = get_continuation_entry_for_sp(thread,
298 callee.is_interpreted_frame() ? callee.interpreter_frame_last_sp() : callee.unextended_sp());
299 assert(ce != nullptr, "callee.unextended_sp(): " INTPTR_FORMAT, p2i(callee.unextended_sp()));
300
301 log_develop_debug(continuations)("continuation_bottom_sender: [" JLONG_FORMAT "] [%d] callee: " INTPTR_FORMAT
302 " sender_sp: " INTPTR_FORMAT,
303 java_tid(thread), thread->osthread()->thread_id(), p2i(callee.sp()), p2i(sender_sp));
304
305 frame entry = ce->to_frame();
306 if (callee.is_interpreted_frame()) {
307 entry.set_sp(sender_sp); // sp != unextended_sp
308 }
309 return entry;
310 }
311
312 address Continuation::get_top_return_pc_post_barrier(JavaThread* thread, address pc) {
313 ContinuationEntry* ce;
314 if (thread != nullptr && is_return_barrier_entry(pc) && (ce = thread->last_continuation()) != nullptr) {
315 return ce->entry_pc();
316 }
317 return pc;
318 }
319
320 void Continuation::set_cont_fastpath_thread_state(JavaThread* thread) {
321 assert(thread != nullptr, "");
322 bool fast = !thread->is_interp_only_mode();
323 thread->set_cont_fastpath_thread_state(fast);
324 }
325
326 void Continuation::notify_deopt(JavaThread* thread, intptr_t* sp) {
327 ContinuationEntry* entry = thread->last_continuation();
328
329 if (entry == nullptr) {
330 return;
331 }
332
333 if (is_sp_in_continuation(entry, sp)) {
334 thread->push_cont_fastpath(sp);
335 return;
336 }
337
338 ContinuationEntry* prev;
339 do {
340 prev = entry;
341 entry = entry->parent();
342 } while (entry != nullptr && !is_sp_in_continuation(entry, sp));
343
344 if (entry == nullptr) {
345 return;
346 }
347 assert(is_sp_in_continuation(entry, sp), "");
348 if (sp > prev->parent_cont_fastpath()) {
349 prev->set_parent_cont_fastpath(sp);
350 }
351 }
352
353 #ifndef PRODUCT
354 void Continuation::describe(FrameValues &values) {
355 JavaThread* thread = JavaThread::active();
356 if (thread != nullptr) {
357 for (ContinuationEntry* ce = thread->last_continuation(); ce != nullptr; ce = ce->parent()) {
358 intptr_t* bottom = ce->entry_sp();
359 if (bottom != nullptr) {
360 values.describe(-1, bottom, "continuation entry");
361 }
362 }
363 }
364 }
365 #endif
366
367 #ifdef ASSERT
368 void Continuation::debug_verify_continuation(oop contOop) {
369 if (!VerifyContinuations) {
370 return;
371 }
372 assert(contOop != nullptr, "");
373 assert(oopDesc::is_oop(contOop), "");
374 ContinuationWrapper cont(contOop);
375
376 assert(oopDesc::is_oop_or_null(cont.tail()), "");
377 assert(cont.chunk_invariant(), "");
378
379 bool nonempty_chunk = false;
380 size_t max_size = 0;
381 int num_chunks = 0;
382 int num_frames = 0;
383 int num_interpreted_frames = 0;
384 int num_oops = 0;
385
386 for (stackChunkOop chunk = cont.tail(); chunk != nullptr; chunk = chunk->parent()) {
387 log_develop_trace(continuations)("debug_verify_continuation chunk %d", num_chunks);
388 chunk->verify(&max_size, &num_oops, &num_frames, &num_interpreted_frames);
389 if (!chunk->is_empty()) {
390 nonempty_chunk = true;
391 }
392 num_chunks++;
393 }
394
395 const bool is_empty = cont.is_empty();
396 assert(!nonempty_chunk || !is_empty, "");
397 assert(is_empty == (!nonempty_chunk && cont.last_frame().is_empty()), "");
398 }
399
400 void Continuation::print(oop continuation) { print_on(tty, continuation); }
401
402 void Continuation::print_on(outputStream* st, oop continuation) {
403 ContinuationWrapper cont(continuation);
404
405 st->print_cr("CONTINUATION: " PTR_FORMAT " done: %d",
406 continuation->identity_hash(), jdk_internal_vm_Continuation::done(continuation));
407 st->print_cr("CHUNKS:");
408 for (stackChunkOop chunk = cont.tail(); chunk != nullptr; chunk = chunk->parent()) {
409 st->print("* ");
410 chunk->print_on(true, st);
411 }
412 }
413 #endif // ASSERT
414
415
416 void continuations_init() { Continuations::init(); }
417
418 void Continuations::init() {
419 Continuation::init();
420 }
421
422 // While virtual threads are in Preview, there are some VM mechanisms we disable if continuations aren't used
423 // See NMethodSweeper::do_stack_scanning and nmethod::is_not_on_continuation_stack
424 bool Continuations::enabled() {
425 // return VMContinuations && Arguments::enable_preview();
426 return VMContinuations;
427 }
428
429 // We initialize the _gc_epoch to 2, because previous_completed_gc_marking_cycle
430 // subtracts the value by 2, and the type is unsigned. We don't want underflow.
431 //
432 // Odd values mean that marking is in progress, and even values mean that no
433 // marking is currently active.
434 uint64_t Continuations::_gc_epoch = 2;
435
436 uint64_t Continuations::gc_epoch() {
437 return _gc_epoch;
438 }
439
440 bool Continuations::is_gc_marking_cycle_active() {
441 // Odd means that marking is active
442 return (_gc_epoch % 2) == 1;
443 }
444
445 uint64_t Continuations::previous_completed_gc_marking_cycle() {
446 if (is_gc_marking_cycle_active()) {
447 return _gc_epoch - 2;
448 } else {
449 return _gc_epoch - 1;
450 }
451 }
452
453 void Continuations::on_gc_marking_cycle_start() {
454 assert(!is_gc_marking_cycle_active(), "Previous marking cycle never ended");
455 ++_gc_epoch;
456 }
457
458 void Continuations::on_gc_marking_cycle_finish() {
459 assert(is_gc_marking_cycle_active(), "Marking cycle started before last one finished");
460 ++_gc_epoch;
461 }
462
463 void Continuations::arm_all_nmethods() {
464 BarrierSetNMethod* bs_nm = BarrierSet::barrier_set()->barrier_set_nmethod();
465 if (bs_nm != NULL) {
466 bs_nm->arm_all_nmethods();
467 }
468 }
469
470 #define CC (char*) /*cast a literal from (const char*)*/
471 #define FN_PTR(f) CAST_FROM_FN_PTR(void*, &f)
472
473 static JNINativeMethod CONT_methods[] = {
474 {CC"pin", CC"()V", FN_PTR(CONT_pin)},
475 {CC"unpin", CC"()V", FN_PTR(CONT_unpin)},
476 {CC"isPinned0", CC"(Ljdk/internal/vm/ContinuationScope;)I", FN_PTR(CONT_isPinned0)},
477 };
478
479 void CONT_RegisterNativeMethods(JNIEnv *env, jclass cls) {
480 Thread* thread = Thread::current();
481 assert(thread->is_Java_thread(), "");
482 ThreadToNativeFromVM trans((JavaThread*)thread);
483 int status = env->RegisterNatives(cls, CONT_methods, sizeof(CONT_methods)/sizeof(JNINativeMethod));
484 guarantee(status == JNI_OK, "register jdk.internal.vm.Continuation natives");
485 guarantee(!env->ExceptionOccurred(), "register jdk.internal.vm.Continuation natives");
486 }