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 "classfile/vmSymbols.hpp"
27 #include "gc/shared/barrierSetNMethod.hpp"
28 #include "oops/method.inline.hpp"
29 #include "runtime/arguments.hpp"
30 #include "runtime/continuation.hpp"
31 #include "runtime/continuationEntry.inline.hpp"
32 #include "runtime/continuationHelper.inline.hpp"
33 #include "runtime/continuationJavaClasses.inline.hpp"
34 #include "runtime/continuationWrapper.inline.hpp"
35 #include "runtime/interfaceSupport.inline.hpp"
36 #include "runtime/javaThread.inline.hpp"
37 #include "runtime/osThread.hpp"
38 #include "runtime/vframe.inline.hpp"
39 #include "runtime/vframe_hp.hpp"
40
41 // defined in continuationFreezeThaw.cpp
42 extern "C" jint JNICALL CONT_isPinned0(JNIEnv* env, jobject cont_scope);
43
44 JVM_ENTRY(void, CONT_pin(JNIEnv* env, jclass cls)) {
45 if (!Continuation::pin(JavaThread::thread_from_jni_environment(env))) {
46 THROW_MSG(vmSymbols::java_lang_IllegalStateException(), "pin overflow");
47 }
48 }
49 JVM_END
50
51 JVM_ENTRY(void, CONT_unpin(JNIEnv* env, jclass cls)) {
52 if (!Continuation::unpin(JavaThread::thread_from_jni_environment(env))) {
53 THROW_MSG(vmSymbols::java_lang_IllegalStateException(), "pin underflow");
54 }
55 }
56 JVM_END
57
58 #ifndef PRODUCT
59 static jlong java_tid(JavaThread* thread) {
60 return java_lang_Thread::thread_id(thread->threadObj());
61 }
62 #endif
63
64 const ContinuationEntry* Continuation::last_continuation(const JavaThread* thread, oop cont_scope) {
65 // guarantee (thread->has_last_Java_frame(), "");
66 for (ContinuationEntry* entry = thread->last_continuation(); entry != nullptr; entry = entry->parent()) {
67 if (cont_scope == jdk_internal_vm_Continuation::scope(entry->cont_oop())) {
68 return entry;
69 }
70 }
71 return nullptr;
72 }
73
74 ContinuationEntry* Continuation::get_continuation_entry_for_continuation(JavaThread* thread, oop continuation) {
75 if (thread == nullptr || continuation == nullptr) {
76 return nullptr;
77 }
78
79 for (ContinuationEntry* entry = thread->last_continuation(); entry != nullptr; entry = entry->parent()) {
80 if (continuation == entry->cont_oop()) {
81 return entry;
82 }
83 }
84 return nullptr;
85 }
86
87 static bool is_on_stack(JavaThread* thread, const ContinuationEntry* entry) {
88 if (entry == nullptr) {
89 return false;
90 }
91
92 assert(thread->is_in_full_stack((address)entry), "");
93 return true;
94 // return false if called when transitioning to Java on return from freeze
95 // return !thread->has_last_Java_frame() || thread->last_Java_sp() < cont->entry_sp();
96 }
97
98 bool Continuation::is_continuation_mounted(JavaThread* thread, oop continuation) {
99 return is_on_stack(thread, get_continuation_entry_for_continuation(thread, continuation));
100 }
101
102 bool Continuation::is_continuation_scope_mounted(JavaThread* thread, oop cont_scope) {
103 return is_on_stack(thread, last_continuation(thread, cont_scope));
104 }
105
106 // When walking the virtual stack, this method returns true
107 // iff the frame is a thawed continuation frame whose
108 // caller is still frozen on the h-stack.
109 // The continuation object can be extracted from the thread.
110 bool Continuation::is_cont_barrier_frame(const frame& f) {
111 assert(f.is_interpreted_frame() || f.cb() != nullptr, "");
112 if (!Continuations::enabled()) return false;
113 return is_return_barrier_entry(f.is_interpreted_frame() ? ContinuationHelper::InterpretedFrame::return_pc(f)
114 : ContinuationHelper::CompiledFrame::return_pc(f));
115 }
116
117 bool Continuation::is_return_barrier_entry(const address pc) {
118 if (!Continuations::enabled()) return false;
119 return pc == StubRoutines::cont_returnBarrier();
120 }
121
122 bool Continuation::is_continuation_enterSpecial(const frame& f) {
123 if (f.cb() == nullptr || !f.cb()->is_compiled()) {
124 return false;
125 }
126 Method* m = f.cb()->as_compiled_method()->method();
127 return (m != nullptr && m->is_continuation_enter_intrinsic());
128 }
129
130 bool Continuation::is_continuation_entry_frame(const frame& f, const RegisterMap *map) {
131 // we can do this because the entry frame is never inlined
132 Method* m = (map != nullptr && map->in_cont() && f.is_interpreted_frame())
133 ? map->stack_chunk()->interpreter_frame_method(f)
134 : ContinuationHelper::Frame::frame_method(f);
135 return m != nullptr && m->intrinsic_id() == vmIntrinsics::_Continuation_enter;
136 }
137
138 // The parameter `sp` should be the actual sp and not the unextended sp because at
139 // least on PPC64 unextended_sp < sp is possible as interpreted frames are trimmed
140 // to the actual size of the expression stack before calls. The problem there is
141 // that even unextended_sp < entry_sp < sp is possible for an interpreted frame.
142 static inline bool is_sp_in_continuation(const ContinuationEntry* entry, intptr_t* const sp) {
143 // entry_sp() returns the unextended_sp which is always greater or equal to the actual sp
144 return entry->entry_sp() > sp;
145 }
146
147 bool Continuation::is_frame_in_continuation(const ContinuationEntry* entry, const frame& f) {
148 return is_sp_in_continuation(entry, f.sp());
149 }
150
151 ContinuationEntry* Continuation::get_continuation_entry_for_sp(JavaThread* thread, intptr_t* const sp) {
152 assert(thread != nullptr, "");
153 ContinuationEntry* entry = thread->last_continuation();
154 while (entry != nullptr && !is_sp_in_continuation(entry, sp)) {
155 entry = entry->parent();
156 }
157 return entry;
158 }
159
160 ContinuationEntry* Continuation::get_continuation_entry_for_entry_frame(JavaThread* thread, const frame& f) {
161 assert(is_continuation_enterSpecial(f), "");
162 ContinuationEntry* entry = (ContinuationEntry*)f.unextended_sp();
163 assert(entry == get_continuation_entry_for_sp(thread, f.sp()-2), "mismatched entry");
164 return entry;
165 }
166
167 bool Continuation::is_frame_in_continuation(JavaThread* thread, const frame& f) {
168 return f.is_heap_frame() || (get_continuation_entry_for_sp(thread, f.sp()) != nullptr);
169 }
170
171 static frame continuation_top_frame(const ContinuationWrapper& cont, RegisterMap* map) {
172 stackChunkOop chunk = cont.last_nonempty_chunk();
173 map->set_stack_chunk(chunk);
174 return chunk != nullptr ? chunk->top_frame(map) : frame();
175 }
176
177 bool Continuation::has_last_Java_frame(oop continuation, frame* frame, RegisterMap* map) {
178 ContinuationWrapper cont(continuation);
179 if (!cont.is_empty()) {
180 *frame = continuation_top_frame(cont, map);
181 return true;
182 } else {
183 return false;
184 }
185 }
186
187 frame Continuation::last_frame(oop continuation, RegisterMap *map) {
188 assert(map != nullptr, "a map must be given");
189 return continuation_top_frame(ContinuationWrapper(continuation), map);
190 }
191
192 frame Continuation::top_frame(const frame& callee, RegisterMap* map) {
193 assert(map != nullptr, "");
194 ContinuationEntry* ce = get_continuation_entry_for_sp(map->thread(), callee.sp());
195 assert(ce != nullptr, "");
196 oop continuation = ce->cont_oop();
197 ContinuationWrapper cont(continuation);
198 return continuation_top_frame(cont, map);
199 }
200
201 javaVFrame* Continuation::last_java_vframe(Handle continuation, RegisterMap *map) {
202 assert(map != nullptr, "a map must be given");
203 if (!ContinuationWrapper(continuation()).is_empty()) {
204 frame f = last_frame(continuation(), map);
205 for (vframe* vf = vframe::new_vframe(&f, map, nullptr); vf; vf = vf->sender()) {
206 if (vf->is_java_frame()) {
207 return javaVFrame::cast(vf);
208 }
209 }
210 }
211 return nullptr;
212 }
213
214 frame Continuation::continuation_parent_frame(RegisterMap* map) {
215 assert(map->in_cont(), "");
216 ContinuationWrapper cont(map);
217 assert(map->thread() != nullptr || !cont.is_mounted(), "");
218
219 log_develop_trace(continuations)("continuation_parent_frame");
220 if (map->update_map()) {
221 // we need to register the link address for the entry frame
222 if (cont.entry() != nullptr) {
223 cont.entry()->update_register_map(map);
224 } else {
225 map->clear();
226 }
227 }
228
229 if (!cont.is_mounted()) { // When we're walking an unmounted continuation and reached the end
230 oop parent = jdk_internal_vm_Continuation::parent(cont.continuation());
231 stackChunkOop chunk = parent != nullptr ? ContinuationWrapper(parent).last_nonempty_chunk() : nullptr;
232 if (chunk != nullptr) {
233 return chunk->top_frame(map);
234 }
235
236 map->set_stack_chunk(nullptr);
237 return frame();
238 }
239
240 map->set_stack_chunk(nullptr);
241
242 #if (defined(X86) || defined(AARCH64) || defined(RISCV64)) && !defined(ZERO)
243 frame sender(cont.entrySP(), cont.entryFP(), cont.entryPC());
244 #else
245 frame sender = frame();
246 Unimplemented();
247 #endif
248
249 return sender;
250 }
251
252 oop Continuation::continuation_scope(oop continuation) {
253 return continuation != nullptr ? jdk_internal_vm_Continuation::scope(continuation) : nullptr;
254 }
255
256 bool Continuation::is_scope_bottom(oop cont_scope, const frame& f, const RegisterMap* map) {
257 if (cont_scope == nullptr || !is_continuation_entry_frame(f, map)) {
258 return false;
259 }
260
261 oop continuation;
262 if (map->in_cont()) {
263 continuation = map->cont();
264 } else {
265 ContinuationEntry* ce = get_continuation_entry_for_sp(map->thread(), f.sp());
266 if (ce == nullptr) {
267 return false;
268 }
269 continuation = ce->cont_oop();
270 }
271 if (continuation == nullptr) {
272 return false;
273 }
274
275 oop sc = continuation_scope(continuation);
276 assert(sc != nullptr, "");
277 return sc == cont_scope;
278 }
279
280 bool Continuation::is_in_usable_stack(address addr, const RegisterMap* map) {
281 ContinuationWrapper cont(map);
282 stackChunkOop chunk = cont.find_chunk_by_address(addr);
283 return chunk != nullptr ? chunk->is_usable_in_chunk(addr) : false;
284 }
285
286 bool Continuation::pin(JavaThread* current) {
287 ContinuationEntry* ce = current->last_continuation();
288 if (ce == nullptr) {
289 return true; // no continuation mounted
290 }
291 return ce->pin();
292 }
293
294 bool Continuation::unpin(JavaThread* current) {
295 ContinuationEntry* ce = current->last_continuation();
296 if (ce == nullptr) {
297 return true; // no continuation mounted
298 }
299 return ce->unpin();
300 }
301
302 frame Continuation::continuation_bottom_sender(JavaThread* thread, const frame& callee, intptr_t* sender_sp) {
303 assert (thread != nullptr, "");
304 ContinuationEntry* ce = get_continuation_entry_for_sp(thread, callee.sp());
305 assert(ce != nullptr, "callee.sp(): " INTPTR_FORMAT, p2i(callee.sp()));
306
307 log_develop_debug(continuations)("continuation_bottom_sender: [" JLONG_FORMAT "] [%d] callee: " INTPTR_FORMAT
308 " sender_sp: " INTPTR_FORMAT,
309 java_tid(thread), thread->osthread()->thread_id(), p2i(callee.sp()), p2i(sender_sp));
310
311 frame entry = ce->to_frame();
312 if (callee.is_interpreted_frame()) {
313 entry.set_sp(sender_sp); // sp != unextended_sp
314 }
315 return entry;
316 }
317
318 address Continuation::get_top_return_pc_post_barrier(JavaThread* thread, address pc) {
319 ContinuationEntry* ce;
320 if (thread != nullptr && is_return_barrier_entry(pc) && (ce = thread->last_continuation()) != nullptr) {
321 return ce->entry_pc();
322 }
323 return pc;
324 }
325
326 void Continuation::set_cont_fastpath_thread_state(JavaThread* thread) {
327 assert(thread != nullptr, "");
328 bool fast = !thread->is_interp_only_mode();
329 thread->set_cont_fastpath_thread_state(fast);
330 }
331
332 void Continuation::notify_deopt(JavaThread* thread, intptr_t* sp) {
333 ContinuationEntry* entry = thread->last_continuation();
334
335 if (entry == nullptr) {
336 return;
337 }
338
339 if (is_sp_in_continuation(entry, sp)) {
340 thread->push_cont_fastpath(sp);
341 return;
342 }
343
344 ContinuationEntry* prev;
345 do {
346 prev = entry;
347 entry = entry->parent();
348 } while (entry != nullptr && !is_sp_in_continuation(entry, sp));
349
350 if (entry == nullptr) {
351 return;
352 }
353 assert(is_sp_in_continuation(entry, sp), "");
354 if (sp > prev->parent_cont_fastpath()) {
355 prev->set_parent_cont_fastpath(sp);
356 }
357 }
358
359 #ifndef PRODUCT
360 void Continuation::describe(FrameValues &values) {
361 JavaThread* thread = JavaThread::active();
362 if (thread != nullptr) {
363 for (ContinuationEntry* ce = thread->last_continuation(); ce != nullptr; ce = ce->parent()) {
364 intptr_t* bottom = ce->entry_sp();
365 if (bottom != nullptr) {
366 values.describe(-1, bottom, "continuation entry");
367 }
368 }
369 }
370 }
371 #endif
372
373 #ifdef ASSERT
374 void Continuation::debug_verify_continuation(oop contOop) {
375 if (!VerifyContinuations) {
376 return;
377 }
378 assert(contOop != nullptr, "");
379 assert(oopDesc::is_oop(contOop), "");
380 ContinuationWrapper cont(contOop);
381
382 assert(oopDesc::is_oop_or_null(cont.tail()), "");
383 assert(cont.chunk_invariant(), "");
384
385 bool nonempty_chunk = false;
386 size_t max_size = 0;
387 int num_chunks = 0;
388 int num_frames = 0;
389 int num_interpreted_frames = 0;
390 int num_oops = 0;
391
392 for (stackChunkOop chunk = cont.tail(); chunk != nullptr; chunk = chunk->parent()) {
393 log_develop_trace(continuations)("debug_verify_continuation chunk %d", num_chunks);
394 chunk->verify(&max_size, &num_oops, &num_frames, &num_interpreted_frames);
395 if (!chunk->is_empty()) {
396 nonempty_chunk = true;
397 }
398 num_chunks++;
399 }
400
401 const bool is_empty = cont.is_empty();
402 assert(!nonempty_chunk || !is_empty, "");
403 assert(is_empty == (!nonempty_chunk && cont.last_frame().is_empty()), "");
404 }
405
406 void Continuation::print(oop continuation) { print_on(tty, continuation); }
407
408 void Continuation::print_on(outputStream* st, oop continuation) {
409 ContinuationWrapper cont(continuation);
410
411 st->print_cr("CONTINUATION: " PTR_FORMAT " done: %d",
412 continuation->identity_hash(), jdk_internal_vm_Continuation::done(continuation));
413 st->print_cr("CHUNKS:");
414 for (stackChunkOop chunk = cont.tail(); chunk != nullptr; chunk = chunk->parent()) {
415 st->print("* ");
416 chunk->print_on(true, st);
417 }
418 }
419 #endif // ASSERT
420
421
422 void continuations_init() { Continuations::init(); }
423
424 void Continuations::init() {
425 Continuation::init();
426 }
427
428 // While virtual threads are in Preview, there are some VM mechanisms we disable if continuations aren't used
429 bool Continuations::enabled() {
430 // return VMContinuations && Arguments::enable_preview();
431 return VMContinuations;
432 }
433
434 #define CC (char*) /*cast a literal from (const char*)*/
435 #define FN_PTR(f) CAST_FROM_FN_PTR(void*, &f)
436
437 static JNINativeMethod CONT_methods[] = {
438 {CC"pin", CC"()V", FN_PTR(CONT_pin)},
439 {CC"unpin", CC"()V", FN_PTR(CONT_unpin)},
440 {CC"isPinned0", CC"(Ljdk/internal/vm/ContinuationScope;)I", FN_PTR(CONT_isPinned0)},
441 };
442
443 void CONT_RegisterNativeMethods(JNIEnv *env, jclass cls) {
444 Thread* thread = Thread::current();
445 assert(thread->is_Java_thread(), "");
446 ThreadToNativeFromVM trans((JavaThread*)thread);
447 int status = env->RegisterNatives(cls, CONT_methods, sizeof(CONT_methods)/sizeof(JNINativeMethod));
448 guarantee(status == JNI_OK, "register jdk.internal.vm.Continuation natives");
449 guarantee(!env->ExceptionOccurred(), "register jdk.internal.vm.Continuation natives");
450 }