1 /*
2 * Copyright (c) 2018, 2025, 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 "classfile/javaClasses.inline.hpp"
26 #include "classfile/vmSymbols.hpp"
27 #include "code/codeCache.inline.hpp"
28 #include "code/nmethod.inline.hpp"
29 #include "code/vmreg.inline.hpp"
30 #include "compiler/oopMap.inline.hpp"
31 #include "gc/shared/continuationGCSupport.inline.hpp"
32 #include "gc/shared/gc_globals.hpp"
33 #include "gc/shared/barrierSet.hpp"
34 #include "gc/shared/memAllocator.hpp"
35 #include "gc/shared/threadLocalAllocBuffer.inline.hpp"
36 #include "interpreter/interpreter.hpp"
37 #include "jfr/jfrEvents.hpp"
38 #include "logging/log.hpp"
39 #include "logging/logStream.hpp"
40 #include "oops/access.inline.hpp"
41 #include "oops/method.inline.hpp"
42 #include "oops/oopsHierarchy.hpp"
43 #include "oops/objArrayOop.inline.hpp"
44 #include "oops/stackChunkOop.inline.hpp"
45 #include "prims/jvmtiThreadState.hpp"
46 #include "runtime/arguments.hpp"
47 #include "runtime/continuation.hpp"
48 #include "runtime/continuationEntry.inline.hpp"
49 #include "runtime/continuationHelper.inline.hpp"
50 #include "runtime/continuationJavaClasses.inline.hpp"
51 #include "runtime/continuationWrapper.inline.hpp"
52 #include "runtime/frame.inline.hpp"
53 #include "runtime/interfaceSupport.inline.hpp"
54 #include "runtime/javaThread.inline.hpp"
55 #include "runtime/jniHandles.inline.hpp"
56 #include "runtime/keepStackGCProcessed.hpp"
57 #include "runtime/objectMonitor.inline.hpp"
58 #include "runtime/orderAccess.hpp"
59 #include "runtime/prefetch.inline.hpp"
60 #include "runtime/smallRegisterMap.inline.hpp"
61 #include "runtime/sharedRuntime.hpp"
62 #include "runtime/stackChunkFrameStream.inline.hpp"
63 #include "runtime/stackFrameStream.inline.hpp"
64 #include "runtime/stackOverflow.hpp"
65 #include "runtime/stackWatermarkSet.inline.hpp"
66 #include "utilities/debug.hpp"
67 #include "utilities/exceptions.hpp"
68 #include "utilities/macros.hpp"
69 #include "utilities/vmError.hpp"
70 #if INCLUDE_ZGC
71 #include "gc/z/zStackChunkGCData.inline.hpp"
72 #endif
73 #if INCLUDE_JFR
74 #include "jfr/jfr.inline.hpp"
75 #endif
76
77 #include <type_traits>
78
79 /*
80 * This file contains the implementation of continuation freezing (yield) and thawing (run).
81 *
82 * This code is very latency-critical and very hot. An ordinary and well-behaved server application
83 * would likely call these operations many thousands of times per second second, on every core.
84 *
85 * Freeze might be called every time the application performs any I/O operation, every time it
86 * acquires a j.u.c. lock, every time it takes a message from a queue, and thaw can be called
87 * multiple times in each of those cases, as it is called by the return barrier, which may be
88 * invoked on method return.
89 *
90 * The amortized budget for each of those two operations is ~100-150ns. That is why, for
91 * example, every effort is made to avoid Java-VM transitions as much as possible.
92 *
93 * On the fast path, all frames are known to be compiled, and the chunk requires no barriers
94 * and so frames simply copied, and the bottom-most one is patched.
95 * On the slow path, internal pointers in interpreted frames are de/relativized to/from offsets
96 * and absolute pointers, and barriers invoked.
97 */
98
99 /************************************************
100
101 Thread-stack layout on freeze/thaw.
102 See corresponding stack-chunk layout in instanceStackChunkKlass.hpp
103
104 +----------------------------+
105 | . |
106 | . |
107 | . |
108 | carrier frames |
109 | |
110 |----------------------------|
111 | |
112 | Continuation.run |
113 | |
114 |============================|
115 | enterSpecial frame |
116 | pc |
117 | rbp |
118 | ----- |
119 ^ | int argsize | = ContinuationEntry
120 | | oopDesc* cont |
121 | | oopDesc* chunk |
122 | | ContinuationEntry* parent |
123 | | ... |
124 | |============================| <------ JavaThread::_cont_entry = entry->sp()
125 | | ? alignment word ? |
126 | |----------------------------| <--\
127 | | | |
128 | | ? caller stack args ? | | argsize (might not be 2-word aligned) words
129 Address | | | | Caller is still in the chunk.
130 | |----------------------------| |
131 | | pc (? return barrier ?) | | This pc contains the return barrier when the bottom-most frame
132 | | rbp | | isn't the last one in the continuation.
133 | | | |
134 | | frame | |
135 | | | |
136 +----------------------------| \__ Continuation frames to be frozen/thawed
137 | | /
138 | frame | |
139 | | |
140 |----------------------------| |
141 | | |
142 | frame | |
143 | | |
144 |----------------------------| <--/
145 | |
146 | doYield/safepoint stub | When preempting forcefully, we could have a safepoint stub
147 | | instead of a doYield stub
148 |============================| <- the sp passed to freeze
149 | |
150 | Native freeze/thaw frames |
151 | . |
152 | . |
153 | . |
154 +----------------------------+
155
156 ************************************************/
157
158 static const bool TEST_THAW_ONE_CHUNK_FRAME = false; // force thawing frames one-at-a-time for testing
159
160 #define CONT_JFR false // emit low-level JFR events that count slow/fast path for continuation performance debugging only
161 #if CONT_JFR
162 #define CONT_JFR_ONLY(code) code
163 #else
164 #define CONT_JFR_ONLY(code)
165 #endif
166
167 // TODO: See AbstractAssembler::generate_stack_overflow_check,
168 // Compile::bang_size_in_bytes(), m->as_SafePoint()->jvms()->interpreter_frame_size()
169 // when we stack-bang, we need to update a thread field with the lowest (farthest) bang point.
170
171 // Data invariants are defined by Continuation::debug_verify_continuation and Continuation::debug_verify_stack_chunk
172
173 // Used to just annotatate cold/hot branches
174 #define LIKELY(condition) (condition)
175 #define UNLIKELY(condition) (condition)
176
177 // debugging functions
178 #ifdef ASSERT
179 extern "C" bool dbg_is_safe(const void* p, intptr_t errvalue); // address p is readable and *(intptr_t*)p != errvalue
180
181 static void verify_continuation(oop continuation) { Continuation::debug_verify_continuation(continuation); }
182
183 static void do_deopt_after_thaw(JavaThread* thread);
184 static bool do_verify_after_thaw(JavaThread* thread, stackChunkOop chunk, outputStream* st);
185 static void log_frames(JavaThread* thread);
186 static void log_frames_after_thaw(JavaThread* thread, ContinuationWrapper& cont, intptr_t* sp, bool preempted);
187 static void print_frame_layout(const frame& f, bool callee_complete, outputStream* st = tty);
188
189 #define assert_pfl(p, ...) \
190 do { \
191 if (!(p)) { \
192 JavaThread* t = JavaThread::active(); \
193 if (t->has_last_Java_frame()) { \
194 tty->print_cr("assert(" #p ") failed:"); \
195 t->print_frame_layout(); \
196 } \
197 } \
198 vmassert(p, __VA_ARGS__); \
199 } while(0)
200
201 #else
202 static void verify_continuation(oop continuation) { }
203 #define assert_pfl(p, ...)
204 #endif
205
206 static freeze_result is_pinned0(JavaThread* thread, oop cont_scope, bool safepoint);
207 template<typename ConfigT, bool preempt> static inline freeze_result freeze_internal(JavaThread* current, intptr_t* const sp);
208
209 static inline int prepare_thaw_internal(JavaThread* thread, bool return_barrier);
210 template<typename ConfigT> static inline intptr_t* thaw_internal(JavaThread* thread, const Continuation::thaw_kind kind);
211
212
213 // Entry point to freeze. Transitions are handled manually
214 // Called from gen_continuation_yield() in sharedRuntime_<cpu>.cpp through Continuation::freeze_entry();
215 template<typename ConfigT>
216 static JRT_BLOCK_ENTRY(int, freeze(JavaThread* current, intptr_t* sp))
217 assert(sp == current->frame_anchor()->last_Java_sp(), "");
218
219 if (current->raw_cont_fastpath() > current->last_continuation()->entry_sp() || current->raw_cont_fastpath() < sp) {
220 current->set_cont_fastpath(nullptr);
221 }
222
223 return checked_cast<int>(ConfigT::freeze(current, sp));
224 JRT_END
225
226 JRT_LEAF(int, Continuation::prepare_thaw(JavaThread* thread, bool return_barrier))
227 return prepare_thaw_internal(thread, return_barrier);
228 JRT_END
229
230 template<typename ConfigT>
231 static JRT_LEAF(intptr_t*, thaw(JavaThread* thread, int kind))
232 // TODO: JRT_LEAF and NoHandleMark is problematic for JFR events.
233 // vFrameStreamCommon allocates Handles in RegisterMap for continuations.
234 // Also the preemption case with JVMTI events enabled might safepoint so
235 // undo the NoSafepointVerifier here and rely on handling by ContinuationWrapper.
236 // JRT_ENTRY instead?
237 ResetNoHandleMark rnhm;
238 DEBUG_ONLY(PauseNoSafepointVerifier pnsv(&__nsv);)
239
240 // we might modify the code cache via BarrierSetNMethod::nmethod_entry_barrier
241 MACOS_AARCH64_ONLY(ThreadWXEnable __wx(WXWrite, thread));
242 return ConfigT::thaw(thread, (Continuation::thaw_kind)kind);
243 JRT_END
244
245 JVM_ENTRY(jint, CONT_isPinned0(JNIEnv* env, jobject cont_scope)) {
246 JavaThread* thread = JavaThread::thread_from_jni_environment(env);
247 return is_pinned0(thread, JNIHandles::resolve(cont_scope), false);
248 }
249 JVM_END
250
251 ///////////
252
253 enum class oop_kind { NARROW, WIDE };
254 template <oop_kind oops, typename BarrierSetT>
255 class Config {
256 public:
257 typedef Config<oops, BarrierSetT> SelfT;
258 using OopT = std::conditional_t<oops == oop_kind::NARROW, narrowOop, oop>;
259
260 static freeze_result freeze(JavaThread* thread, intptr_t* const sp) {
261 freeze_result res = freeze_internal<SelfT, false>(thread, sp);
262 JFR_ONLY(assert((res == freeze_ok) || (res == thread->last_freeze_fail_result()), "freeze failure not set"));
263 return res;
264 }
265
266 static freeze_result freeze_preempt(JavaThread* thread, intptr_t* const sp) {
267 return freeze_internal<SelfT, true>(thread, sp);
268 }
269
270 static intptr_t* thaw(JavaThread* thread, Continuation::thaw_kind kind) {
271 return thaw_internal<SelfT>(thread, kind);
272 }
273 };
274
275 #ifdef _WINDOWS
276 static void map_stack_pages(JavaThread* thread, size_t size, address sp) {
277 address new_sp = sp - size;
278 address watermark = thread->stack_overflow_state()->shadow_zone_growth_watermark();
279
280 if (new_sp < watermark) {
281 size_t page_size = os::vm_page_size();
282 address last_touched_page = watermark - StackOverflow::stack_shadow_zone_size();
283 size_t pages_to_touch = align_up(watermark - new_sp, page_size) / page_size;
284 while (pages_to_touch-- > 0) {
285 last_touched_page -= page_size;
286 *last_touched_page = 0;
287 }
288 thread->stack_overflow_state()->set_shadow_zone_growth_watermark(new_sp);
289 }
290 }
291 #endif
292
293 static bool stack_overflow_check(JavaThread* thread, size_t size, address sp) {
294 const size_t page_size = os::vm_page_size();
295 if (size > page_size) {
296 if (sp - size < thread->stack_overflow_state()->shadow_zone_safe_limit()) {
297 return false;
298 }
299 WINDOWS_ONLY(map_stack_pages(thread, size, sp));
300 }
301 return true;
302 }
303
304 #ifdef ASSERT
305 static oop get_continuation(JavaThread* thread) {
306 assert(thread != nullptr, "");
307 assert(thread->threadObj() != nullptr, "");
308 return java_lang_Thread::continuation(thread->threadObj());
309 }
310 #endif // ASSERT
311
312 inline void clear_anchor(JavaThread* thread) {
313 thread->frame_anchor()->clear();
314 }
315
316 static void set_anchor(JavaThread* thread, intptr_t* sp, address pc) {
317 assert(pc != nullptr, "");
318
319 JavaFrameAnchor* anchor = thread->frame_anchor();
320 anchor->set_last_Java_sp(sp);
321 anchor->set_last_Java_pc(pc);
322 ContinuationHelper::set_anchor_pd(anchor, sp);
323
324 assert(thread->has_last_Java_frame(), "");
325 assert(thread->last_frame().cb() != nullptr, "");
326 }
327
328 static void set_anchor(JavaThread* thread, intptr_t* sp) {
329 address pc = ContinuationHelper::return_address_at(
330 sp - frame::sender_sp_ret_address_offset());
331 set_anchor(thread, sp, pc);
332 }
333
334 static void set_anchor_to_entry(JavaThread* thread, ContinuationEntry* entry) {
335 JavaFrameAnchor* anchor = thread->frame_anchor();
336 anchor->set_last_Java_sp(entry->entry_sp());
337 anchor->set_last_Java_pc(entry->entry_pc());
338 ContinuationHelper::set_anchor_to_entry_pd(anchor, entry);
339
340 assert(thread->has_last_Java_frame(), "");
341 assert(thread->last_frame().cb() != nullptr, "");
342 }
343
344 #if CONT_JFR
345 class FreezeThawJfrInfo : public StackObj {
346 short _e_size;
347 short _e_num_interpreted_frames;
348 public:
349
350 FreezeThawJfrInfo() : _e_size(0), _e_num_interpreted_frames(0) {}
351 inline void record_interpreted_frame() { _e_num_interpreted_frames++; }
352 inline void record_size_copied(int size) { _e_size += size << LogBytesPerWord; }
353 template<typename Event> void post_jfr_event(Event *e, oop continuation, JavaThread* jt);
354 };
355
356 template<typename Event> void FreezeThawJfrInfo::post_jfr_event(Event* e, oop continuation, JavaThread* jt) {
357 if (e->should_commit()) {
358 log_develop_trace(continuations)("JFR event: iframes: %d size: %d", _e_num_interpreted_frames, _e_size);
359 e->set_carrierThread(JFR_JVM_THREAD_ID(jt));
360 e->set_continuationClass(continuation->klass());
361 e->set_interpretedFrames(_e_num_interpreted_frames);
362 e->set_size(_e_size);
363 e->commit();
364 }
365 }
366 #endif // CONT_JFR
367
368 /////////////// FREEZE ////
369
370 class FreezeBase : public StackObj {
371 protected:
372 JavaThread* const _thread;
373 ContinuationWrapper& _cont;
374 bool _barriers; // only set when we allocate a chunk
375
376 intptr_t* _bottom_address;
377
378 // Used for preemption only
379 const bool _preempt;
380 frame _last_frame;
381
382 // Used to support freezing with held monitors
383 int _monitors_in_lockstack;
384
385 int _freeze_size; // total size of all frames plus metadata in words.
386 int _total_align_size;
387
388 intptr_t* _cont_stack_top;
389 intptr_t* _cont_stack_bottom;
390
391 CONT_JFR_ONLY(FreezeThawJfrInfo _jfr_info;)
392
393 #ifdef ASSERT
394 intptr_t* _orig_chunk_sp;
395 int _fast_freeze_size;
396 bool _empty;
397 #endif
398
399 JvmtiSampledObjectAllocEventCollector* _jvmti_event_collector;
400
401 NOT_PRODUCT(int _frames;)
402 DEBUG_ONLY(intptr_t* _last_write;)
403
404 inline FreezeBase(JavaThread* thread, ContinuationWrapper& cont, intptr_t* sp, bool preempt);
405
406 public:
407 NOINLINE freeze_result freeze_slow();
408 void freeze_fast_existing_chunk();
409
410 CONT_JFR_ONLY(FreezeThawJfrInfo& jfr_info() { return _jfr_info; })
411 void set_jvmti_event_collector(JvmtiSampledObjectAllocEventCollector* jsoaec) { _jvmti_event_collector = jsoaec; }
412
413 inline int size_if_fast_freeze_available();
414
415 inline frame& last_frame() { return _last_frame; }
416
417 #ifdef ASSERT
418 bool check_valid_fast_path();
419 #endif
420
421 protected:
422 inline void init_rest();
423 void throw_stack_overflow_on_humongous_chunk();
424
425 // fast path
426 inline void copy_to_chunk(intptr_t* from, intptr_t* to, int size);
427 inline void unwind_frames();
428 inline void patch_stack_pd(intptr_t* frame_sp, intptr_t* heap_sp);
429
430 // slow path
431 virtual stackChunkOop allocate_chunk_slow(size_t stack_size, int argsize_md) = 0;
432
433 int cont_size() { return pointer_delta_as_int(_cont_stack_bottom, _cont_stack_top); }
434
435 private:
436 // slow path
437 frame freeze_start_frame();
438 frame freeze_start_frame_on_preempt();
439 NOINLINE freeze_result recurse_freeze(frame& f, frame& caller, int callee_argsize, bool callee_interpreted, bool top);
440 inline frame freeze_start_frame_yield_stub();
441 template<typename FKind>
442 inline freeze_result recurse_freeze_java_frame(const frame& f, frame& caller, int fsize, int argsize);
443 inline void before_freeze_java_frame(const frame& f, const frame& caller, int fsize, int argsize, bool is_bottom_frame);
444 inline void after_freeze_java_frame(const frame& hf, bool is_bottom_frame);
445 freeze_result finalize_freeze(const frame& callee, frame& caller, int argsize);
446 void patch(const frame& f, frame& hf, const frame& caller, bool is_bottom_frame);
447 NOINLINE freeze_result recurse_freeze_interpreted_frame(frame& f, frame& caller, int callee_argsize, bool callee_interpreted);
448 freeze_result recurse_freeze_compiled_frame(frame& f, frame& caller, int callee_argsize, bool callee_interpreted);
449 NOINLINE freeze_result recurse_freeze_stub_frame(frame& f, frame& caller);
450 NOINLINE freeze_result recurse_freeze_native_frame(frame& f, frame& caller);
451 NOINLINE void finish_freeze(const frame& f, const frame& top);
452
453 void freeze_lockstack(stackChunkOop chunk);
454
455 inline bool stack_overflow();
456
457 static frame sender(const frame& f) { return f.is_interpreted_frame() ? sender<ContinuationHelper::InterpretedFrame>(f)
458 : sender<ContinuationHelper::NonInterpretedUnknownFrame>(f); }
459 template<typename FKind> static inline frame sender(const frame& f);
460 template<typename FKind> frame new_heap_frame(frame& f, frame& caller, int size_adjust = 0);
461 inline void set_top_frame_metadata_pd(const frame& hf);
462 inline void patch_pd(frame& callee, const frame& caller, bool is_bottom_frame);
463 inline void patch_pd_unused(intptr_t* sp);
464 void adjust_interpreted_frame_unextended_sp(frame& f);
465 static inline void prepare_freeze_interpreted_top_frame(frame& f);
466 static inline void relativize_interpreted_frame_metadata(const frame& f, const frame& hf);
467
468 protected:
469 void freeze_fast_copy(stackChunkOop chunk, int chunk_start_sp CONT_JFR_ONLY(COMMA bool chunk_is_allocated));
470 bool freeze_fast_new_chunk(stackChunkOop chunk);
471 };
472
473 template <typename ConfigT>
474 class Freeze : public FreezeBase {
475 private:
476 stackChunkOop allocate_chunk(size_t stack_size, int argsize_md);
477
478 public:
479 inline Freeze(JavaThread* thread, ContinuationWrapper& cont, intptr_t* frame_sp, bool preempt)
480 : FreezeBase(thread, cont, frame_sp, preempt) {}
481
482 freeze_result try_freeze_fast();
483
484 protected:
485 virtual stackChunkOop allocate_chunk_slow(size_t stack_size, int argsize_md) override { return allocate_chunk(stack_size, argsize_md); }
486 };
487
488 FreezeBase::FreezeBase(JavaThread* thread, ContinuationWrapper& cont, intptr_t* frame_sp, bool preempt) :
489 _thread(thread), _cont(cont), _barriers(false), _preempt(preempt), _last_frame(false /* no initialization */) {
490 DEBUG_ONLY(_jvmti_event_collector = nullptr;)
491
492 assert(_thread != nullptr, "");
493 assert(_thread->last_continuation()->entry_sp() == _cont.entrySP(), "");
494
495 DEBUG_ONLY(_cont.entry()->verify_cookie();)
496
497 assert(!Interpreter::contains(_cont.entryPC()), "");
498
499 _bottom_address = _cont.entrySP() - _cont.entry_frame_extension();
500 #ifdef _LP64
501 if (((intptr_t)_bottom_address & 0xf) != 0) {
502 _bottom_address--;
503 }
504 assert(is_aligned(_bottom_address, frame::frame_alignment), "");
505 #endif
506
507 log_develop_trace(continuations)("bottom_address: " INTPTR_FORMAT " entrySP: " INTPTR_FORMAT " argsize: " PTR_FORMAT,
508 p2i(_bottom_address), p2i(_cont.entrySP()), (_cont.entrySP() - _bottom_address) << LogBytesPerWord);
509 assert(_bottom_address != nullptr, "");
510 assert(_bottom_address <= _cont.entrySP(), "");
511 DEBUG_ONLY(_last_write = nullptr;)
512
513 assert(_cont.chunk_invariant(), "");
514 assert(!Interpreter::contains(_cont.entryPC()), "");
515 #if !defined(PPC64) || defined(ZERO)
516 static const int doYield_stub_frame_size = frame::metadata_words;
517 #else
518 static const int doYield_stub_frame_size = frame::native_abi_reg_args_size >> LogBytesPerWord;
519 #endif
520 // With preemption doYield() might not have been resolved yet
521 assert(_preempt || SharedRuntime::cont_doYield_stub()->frame_size() == doYield_stub_frame_size, "");
522
523 if (preempt) {
524 _last_frame = _thread->last_frame();
525 }
526
527 // properties of the continuation on the stack; all sizes are in words
528 _cont_stack_top = frame_sp + (!preempt ? doYield_stub_frame_size : 0); // we don't freeze the doYield stub frame
529 _cont_stack_bottom = _cont.entrySP() + (_cont.argsize() == 0 ? frame::metadata_words_at_top : 0)
530 - ContinuationHelper::frame_align_words(_cont.argsize()); // see alignment in thaw
531
532 log_develop_trace(continuations)("freeze size: %d argsize: %d top: " INTPTR_FORMAT " bottom: " INTPTR_FORMAT,
533 cont_size(), _cont.argsize(), p2i(_cont_stack_top), p2i(_cont_stack_bottom));
534 assert(cont_size() > 0, "");
535
536 if (LockingMode != LM_LIGHTWEIGHT) {
537 _monitors_in_lockstack = 0;
538 } else {
539 _monitors_in_lockstack = _thread->lock_stack().monitor_count();
540 }
541 }
542
543 void FreezeBase::init_rest() { // we want to postpone some initialization after chunk handling
544 _freeze_size = 0;
545 _total_align_size = 0;
546 NOT_PRODUCT(_frames = 0;)
547 }
548
549 void FreezeBase::freeze_lockstack(stackChunkOop chunk) {
550 assert(chunk->sp_address() - chunk->start_address() >= _monitors_in_lockstack, "no room for lockstack");
551
552 _thread->lock_stack().move_to_address((oop*)chunk->start_address());
553 chunk->set_lockstack_size(checked_cast<uint8_t>(_monitors_in_lockstack));
554 chunk->set_has_lockstack(true);
555 }
556
557 void FreezeBase::copy_to_chunk(intptr_t* from, intptr_t* to, int size) {
558 stackChunkOop chunk = _cont.tail();
559 chunk->copy_from_stack_to_chunk(from, to, size);
560 CONT_JFR_ONLY(_jfr_info.record_size_copied(size);)
561
562 #ifdef ASSERT
563 if (_last_write != nullptr) {
564 assert(_last_write == to + size, "Missed a spot: _last_write: " INTPTR_FORMAT " to+size: " INTPTR_FORMAT
565 " stack_size: %d _last_write offset: " PTR_FORMAT " to+size: " PTR_FORMAT, p2i(_last_write), p2i(to+size),
566 chunk->stack_size(), _last_write-chunk->start_address(), to+size-chunk->start_address());
567 _last_write = to;
568 }
569 #endif
570 }
571
572 static void assert_frames_in_continuation_are_safe(JavaThread* thread) {
573 #ifdef ASSERT
574 StackWatermark* watermark = StackWatermarkSet::get(thread, StackWatermarkKind::gc);
575 if (watermark == nullptr) {
576 return;
577 }
578 ContinuationEntry* ce = thread->last_continuation();
579 RegisterMap map(thread,
580 RegisterMap::UpdateMap::include,
581 RegisterMap::ProcessFrames::skip,
582 RegisterMap::WalkContinuation::skip);
583 map.set_include_argument_oops(false);
584 for (frame f = thread->last_frame(); Continuation::is_frame_in_continuation(ce, f); f = f.sender(&map)) {
585 watermark->assert_is_frame_safe(f);
586 }
587 #endif // ASSERT
588 }
589
590 #ifdef ASSERT
591 static bool monitors_on_stack(JavaThread* thread) {
592 assert_frames_in_continuation_are_safe(thread);
593 ContinuationEntry* ce = thread->last_continuation();
594 RegisterMap map(thread,
595 RegisterMap::UpdateMap::include,
596 RegisterMap::ProcessFrames::skip,
597 RegisterMap::WalkContinuation::skip);
598 map.set_include_argument_oops(false);
599 for (frame f = thread->last_frame(); Continuation::is_frame_in_continuation(ce, f); f = f.sender(&map)) {
600 if ((f.is_interpreted_frame() && ContinuationHelper::InterpretedFrame::is_owning_locks(f)) ||
601 (f.is_compiled_frame() && ContinuationHelper::CompiledFrame::is_owning_locks(map.thread(), &map, f)) ||
602 (f.is_native_frame() && ContinuationHelper::NativeFrame::is_owning_locks(map.thread(), f))) {
603 return true;
604 }
605 }
606 return false;
607 }
608 #endif // ASSERT
609
610 // Called _after_ the last possible safepoint during the freeze operation (chunk allocation)
611 void FreezeBase::unwind_frames() {
612 ContinuationEntry* entry = _cont.entry();
613 entry->flush_stack_processing(_thread);
614 assert_frames_in_continuation_are_safe(_thread);
615 JFR_ONLY(Jfr::check_and_process_sample_request(_thread);)
616 assert(LockingMode != LM_LEGACY || !monitors_on_stack(_thread), "unexpected monitors on stack");
617 set_anchor_to_entry(_thread, entry);
618 }
619
620 template <typename ConfigT>
621 freeze_result Freeze<ConfigT>::try_freeze_fast() {
622 assert(_thread->thread_state() == _thread_in_vm, "");
623 assert(_thread->cont_fastpath(), "");
624
625 DEBUG_ONLY(_fast_freeze_size = size_if_fast_freeze_available();)
626 assert(_fast_freeze_size == 0, "");
627
628 stackChunkOop chunk = allocate_chunk(cont_size() + frame::metadata_words + _monitors_in_lockstack, _cont.argsize() + frame::metadata_words_at_top);
629 if (freeze_fast_new_chunk(chunk)) {
630 return freeze_ok;
631 }
632 if (_thread->has_pending_exception()) {
633 return freeze_exception;
634 }
635
636 // TODO R REMOVE when deopt change is fixed
637 assert(!_thread->cont_fastpath() || _barriers, "");
638 log_develop_trace(continuations)("-- RETRYING SLOW --");
639 return freeze_slow();
640 }
641
642 // Returns size needed if the continuation fits, otherwise 0.
643 int FreezeBase::size_if_fast_freeze_available() {
644 stackChunkOop chunk = _cont.tail();
645 if (chunk == nullptr || chunk->is_gc_mode() || chunk->requires_barriers() || chunk->has_mixed_frames()) {
646 log_develop_trace(continuations)("chunk available %s", chunk == nullptr ? "no chunk" : "chunk requires barriers");
647 return 0;
648 }
649
650 int total_size_needed = cont_size();
651 const int chunk_sp = chunk->sp();
652
653 // argsize can be nonzero if we have a caller, but the caller could be in a non-empty parent chunk,
654 // so we subtract it only if we overlap with the caller, i.e. the current chunk isn't empty.
655 // Consider leaving the chunk's argsize set when emptying it and removing the following branch,
656 // although that would require changing stackChunkOopDesc::is_empty
657 if (!chunk->is_empty()) {
658 total_size_needed -= _cont.argsize() + frame::metadata_words_at_top;
659 }
660
661 total_size_needed += _monitors_in_lockstack;
662
663 int chunk_free_room = chunk_sp - frame::metadata_words_at_bottom;
664 bool available = chunk_free_room >= total_size_needed;
665 log_develop_trace(continuations)("chunk available: %s size: %d argsize: %d top: " INTPTR_FORMAT " bottom: " INTPTR_FORMAT,
666 available ? "yes" : "no" , total_size_needed, _cont.argsize(), p2i(_cont_stack_top), p2i(_cont_stack_bottom));
667 return available ? total_size_needed : 0;
668 }
669
670 void FreezeBase::freeze_fast_existing_chunk() {
671 stackChunkOop chunk = _cont.tail();
672
673 DEBUG_ONLY(_fast_freeze_size = size_if_fast_freeze_available();)
674 assert(_fast_freeze_size > 0, "");
675
676 if (!chunk->is_empty()) { // we are copying into a non-empty chunk
677 DEBUG_ONLY(_empty = false;)
678 DEBUG_ONLY(_orig_chunk_sp = chunk->sp_address();)
679 #ifdef ASSERT
680 {
681 intptr_t* retaddr_slot = (chunk->sp_address()
682 - frame::sender_sp_ret_address_offset());
683 assert(ContinuationHelper::return_address_at(retaddr_slot) == chunk->pc(),
684 "unexpected saved return address");
685 }
686 #endif
687
688 // the chunk's sp before the freeze, adjusted to point beyond the stack-passed arguments in the topmost frame
689 // we overlap; we'll overwrite the chunk's top frame's callee arguments
690 const int chunk_start_sp = chunk->sp() + _cont.argsize() + frame::metadata_words_at_top;
691 assert(chunk_start_sp <= chunk->stack_size(), "sp not pointing into stack");
692
693 // increase max_size by what we're freezing minus the overlap
694 chunk->set_max_thawing_size(chunk->max_thawing_size() + cont_size() - _cont.argsize() - frame::metadata_words_at_top);
695
696 intptr_t* const bottom_sp = _cont_stack_bottom - _cont.argsize() - frame::metadata_words_at_top;
697 assert(bottom_sp == _bottom_address, "");
698 // Because the chunk isn't empty, we know there's a caller in the chunk, therefore the bottom-most frame
699 // should have a return barrier (installed back when we thawed it).
700 #ifdef ASSERT
701 {
702 intptr_t* retaddr_slot = (bottom_sp
703 - frame::sender_sp_ret_address_offset());
704 assert(ContinuationHelper::return_address_at(retaddr_slot)
705 == StubRoutines::cont_returnBarrier(),
706 "should be the continuation return barrier");
707 }
708 #endif
709 // We copy the fp from the chunk back to the stack because it contains some caller data,
710 // including, possibly, an oop that might have gone stale since we thawed.
711 patch_stack_pd(bottom_sp, chunk->sp_address());
712 // we don't patch the return pc at this time, so as not to make the stack unwalkable for async walks
713
714 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA false));
715 } else { // the chunk is empty
716 const int chunk_start_sp = chunk->stack_size();
717
718 DEBUG_ONLY(_empty = true;)
719 DEBUG_ONLY(_orig_chunk_sp = chunk->start_address() + chunk_start_sp;)
720
721 chunk->set_max_thawing_size(cont_size());
722 chunk->set_bottom(chunk_start_sp - _cont.argsize() - frame::metadata_words_at_top);
723 chunk->set_sp(chunk->bottom());
724
725 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA false));
726 }
727 }
728
729 bool FreezeBase::freeze_fast_new_chunk(stackChunkOop chunk) {
730 DEBUG_ONLY(_empty = true;)
731
732 // Install new chunk
733 _cont.set_tail(chunk);
734
735 if (UNLIKELY(chunk == nullptr || !_thread->cont_fastpath() || _barriers)) { // OOME/probably humongous
736 log_develop_trace(continuations)("Retrying slow. Barriers: %d", _barriers);
737 return false;
738 }
739
740 chunk->set_max_thawing_size(cont_size());
741
742 // in a fresh chunk, we freeze *with* the bottom-most frame's stack arguments.
743 // They'll then be stored twice: in the chunk and in the parent chunk's top frame
744 const int chunk_start_sp = cont_size() + frame::metadata_words + _monitors_in_lockstack;
745 assert(chunk_start_sp == chunk->stack_size(), "");
746
747 DEBUG_ONLY(_orig_chunk_sp = chunk->start_address() + chunk_start_sp;)
748
749 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA true));
750
751 return true;
752 }
753
754 void FreezeBase::freeze_fast_copy(stackChunkOop chunk, int chunk_start_sp CONT_JFR_ONLY(COMMA bool chunk_is_allocated)) {
755 assert(chunk != nullptr, "");
756 assert(!chunk->has_mixed_frames(), "");
757 assert(!chunk->is_gc_mode(), "");
758 assert(!chunk->has_bitmap(), "");
759 assert(!chunk->requires_barriers(), "");
760 assert(chunk == _cont.tail(), "");
761
762 // We unwind frames after the last safepoint so that the GC will have found the oops in the frames, but before
763 // writing into the chunk. This is so that an asynchronous stack walk (not at a safepoint) that suspends us here
764 // will either see no continuation on the stack, or a consistent chunk.
765 unwind_frames();
766
767 log_develop_trace(continuations)("freeze_fast start: chunk " INTPTR_FORMAT " size: %d orig sp: %d argsize: %d",
768 p2i((oopDesc*)chunk), chunk->stack_size(), chunk_start_sp, _cont.argsize());
769 assert(chunk_start_sp <= chunk->stack_size(), "");
770 assert(chunk_start_sp >= cont_size(), "no room in the chunk");
771
772 const int chunk_new_sp = chunk_start_sp - cont_size(); // the chunk's new sp, after freeze
773 assert(!(_fast_freeze_size > 0) || (_orig_chunk_sp - (chunk->start_address() + chunk_new_sp)) == (_fast_freeze_size - _monitors_in_lockstack), "");
774
775 intptr_t* chunk_top = chunk->start_address() + chunk_new_sp;
776 #ifdef ASSERT
777 if (!_empty) {
778 intptr_t* retaddr_slot = (_orig_chunk_sp
779 - frame::sender_sp_ret_address_offset());
780 assert(ContinuationHelper::return_address_at(retaddr_slot) == chunk->pc(),
781 "unexpected saved return address");
782 }
783 #endif
784
785 log_develop_trace(continuations)("freeze_fast start: " INTPTR_FORMAT " sp: %d chunk_top: " INTPTR_FORMAT,
786 p2i(chunk->start_address()), chunk_new_sp, p2i(chunk_top));
787
788 int adjust = frame::metadata_words_at_bottom;
789 #if INCLUDE_ASAN && defined(AARCH64)
790 // Reading at offset frame::metadata_words_at_bottom from _cont_stack_top
791 // will accesss memory at the callee frame, which on preemption cases will
792 // be the VM native method being called. The Arm 64-bit ABI doesn't specify
793 // a location where the frame record (returnpc+fp) has to be stored within
794 // a stack frame, and GCC currently chooses to save it at the top of the
795 // frame (lowest address). ASan treats this memory access in the callee as
796 // an overflow access to one of the locals stored in that frame. For these
797 // preemption cases we don't need to read these words anyways so we avoid it.
798 if (_preempt) {
799 adjust = 0;
800 }
801 #endif
802 intptr_t* from = _cont_stack_top - adjust;
803 intptr_t* to = chunk_top - adjust;
804 copy_to_chunk(from, to, cont_size() + adjust);
805 // Because we're not patched yet, the chunk is now in a bad state
806
807 // patch return pc of the bottom-most frozen frame (now in the chunk)
808 // with the actual caller's return address
809 intptr_t* chunk_bottom_retaddr_slot = (chunk_top + cont_size()
810 - _cont.argsize()
811 - frame::metadata_words_at_top
812 - frame::sender_sp_ret_address_offset());
813 #ifdef ASSERT
814 if (!_empty) {
815 assert(ContinuationHelper::return_address_at(chunk_bottom_retaddr_slot)
816 == StubRoutines::cont_returnBarrier(),
817 "should be the continuation return barrier");
818 }
819 #endif
820 ContinuationHelper::patch_return_address_at(chunk_bottom_retaddr_slot,
821 chunk->pc());
822
823 // We're always writing to a young chunk, so the GC can't see it until the next safepoint.
824 chunk->set_sp(chunk_new_sp);
825
826 // set chunk->pc to the return address of the topmost frame in the chunk
827 if (_preempt) {
828 // On aarch64/riscv64, the return pc of the top frame won't necessarily be at sp[-1].
829 // Also, on x64, if the top frame is the native wrapper frame, sp[-1] will not
830 // be the pc we used when creating the oopmap. Get the top's frame last pc from
831 // the anchor instead.
832 address last_pc = _last_frame.pc();
833 ContinuationHelper::patch_return_address_at(chunk_top - frame::sender_sp_ret_address_offset(), last_pc);
834 chunk->set_pc(last_pc);
835 // For stub/native frames the fp is not used while frozen, and will be constructed
836 // again when thawing the frame (see ThawBase::handle_preempted_continuation). We
837 // patch it with a special bad address to help with debugging, particularly when
838 // inspecting frames and identifying invalid accesses.
839 patch_pd_unused(chunk_top);
840 } else {
841 chunk->set_pc(ContinuationHelper::return_address_at(
842 _cont_stack_top - frame::sender_sp_ret_address_offset()));
843 }
844
845 if (_monitors_in_lockstack > 0) {
846 freeze_lockstack(chunk);
847 }
848
849 _cont.write();
850
851 log_develop_trace(continuations)("FREEZE CHUNK #" INTPTR_FORMAT " (young)", _cont.hash());
852 LogTarget(Trace, continuations) lt;
853 if (lt.develop_is_enabled()) {
854 LogStream ls(lt);
855 chunk->print_on(true, &ls);
856 }
857
858 // Verification
859 assert(_cont.chunk_invariant(), "");
860 chunk->verify();
861
862 #if CONT_JFR
863 EventContinuationFreezeFast e;
864 if (e.should_commit()) {
865 e.set_id(cast_from_oop<u8>(chunk));
866 DEBUG_ONLY(e.set_allocate(chunk_is_allocated);)
867 e.set_size(cont_size() << LogBytesPerWord);
868 e.commit();
869 }
870 #endif
871 }
872
873 NOINLINE freeze_result FreezeBase::freeze_slow() {
874 #ifdef ASSERT
875 ResourceMark rm;
876 #endif
877
878 log_develop_trace(continuations)("freeze_slow #" INTPTR_FORMAT, _cont.hash());
879 assert(_thread->thread_state() == _thread_in_vm || _thread->thread_state() == _thread_blocked, "");
880
881 #if CONT_JFR
882 EventContinuationFreezeSlow e;
883 if (e.should_commit()) {
884 e.set_id(cast_from_oop<u8>(_cont.continuation()));
885 e.commit();
886 }
887 #endif
888
889 init_rest();
890
891 HandleMark hm(Thread::current());
892
893 frame f = freeze_start_frame();
894
895 LogTarget(Debug, continuations) lt;
896 if (lt.develop_is_enabled()) {
897 LogStream ls(lt);
898 f.print_on(&ls);
899 }
900
901 frame caller; // the frozen caller in the chunk
902 freeze_result res = recurse_freeze(f, caller, 0, false, true);
903
904 if (res == freeze_ok) {
905 finish_freeze(f, caller);
906 _cont.write();
907 }
908
909 return res;
910 }
911
912 frame FreezeBase::freeze_start_frame() {
913 if (LIKELY(!_preempt)) {
914 return freeze_start_frame_yield_stub();
915 } else {
916 return freeze_start_frame_on_preempt();
917 }
918 }
919
920 frame FreezeBase::freeze_start_frame_yield_stub() {
921 frame f = _thread->last_frame();
922 assert(SharedRuntime::cont_doYield_stub()->contains(f.pc()), "must be");
923 f = sender<ContinuationHelper::NonInterpretedUnknownFrame>(f);
924 assert(Continuation::is_frame_in_continuation(_thread->last_continuation(), f), "");
925 return f;
926 }
927
928 frame FreezeBase::freeze_start_frame_on_preempt() {
929 assert(_last_frame.sp() == _thread->last_frame().sp(), "_last_frame should be already initialized");
930 assert(Continuation::is_frame_in_continuation(_thread->last_continuation(), _last_frame), "");
931 return _last_frame;
932 }
933
934 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
935 NOINLINE freeze_result FreezeBase::recurse_freeze(frame& f, frame& caller, int callee_argsize, bool callee_interpreted, bool top) {
936 assert(f.unextended_sp() < _bottom_address, ""); // see recurse_freeze_java_frame
937 assert(f.is_interpreted_frame() || ((top && _preempt) == ContinuationHelper::Frame::is_stub(f.cb()))
938 || ((top && _preempt) == f.is_native_frame()), "");
939
940 if (stack_overflow()) {
941 return freeze_exception;
942 }
943
944 if (f.is_compiled_frame()) {
945 if (UNLIKELY(f.oop_map() == nullptr)) {
946 // special native frame
947 return freeze_pinned_native;
948 }
949 return recurse_freeze_compiled_frame(f, caller, callee_argsize, callee_interpreted);
950 } else if (f.is_interpreted_frame()) {
951 assert(!f.interpreter_frame_method()->is_native() || (top && _preempt), "");
952 return recurse_freeze_interpreted_frame(f, caller, callee_argsize, callee_interpreted);
953 } else if (top && _preempt) {
954 assert(f.is_native_frame() || f.is_runtime_frame(), "");
955 return f.is_native_frame() ? recurse_freeze_native_frame(f, caller) : recurse_freeze_stub_frame(f, caller);
956 } else {
957 // Frame can't be frozen. Most likely the call_stub or upcall_stub
958 // which indicates there are further natives frames up the stack.
959 return freeze_pinned_native;
960 }
961 }
962
963 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
964 // See also StackChunkFrameStream<frame_kind>::frame_size()
965 template<typename FKind>
966 inline freeze_result FreezeBase::recurse_freeze_java_frame(const frame& f, frame& caller, int fsize, int argsize) {
967 assert(FKind::is_instance(f), "");
968
969 assert(fsize > 0, "");
970 assert(argsize >= 0, "");
971 _freeze_size += fsize;
972 NOT_PRODUCT(_frames++;)
973
974 assert(FKind::frame_bottom(f) <= _bottom_address, "");
975
976 // We don't use FKind::frame_bottom(f) == _bottom_address because on x64 there's sometimes an extra word between
977 // enterSpecial and an interpreted frame
978 if (FKind::frame_bottom(f) >= _bottom_address - 1) {
979 return finalize_freeze(f, caller, argsize); // recursion end
980 } else {
981 frame senderf = sender<FKind>(f);
982 assert(FKind::interpreted || senderf.sp() == senderf.unextended_sp(), "");
983 freeze_result result = recurse_freeze(senderf, caller, argsize, FKind::interpreted, false); // recursive call
984 return result;
985 }
986 }
987
988 inline void FreezeBase::before_freeze_java_frame(const frame& f, const frame& caller, int fsize, int argsize, bool is_bottom_frame) {
989 LogTarget(Trace, continuations) lt;
990 if (lt.develop_is_enabled()) {
991 LogStream ls(lt);
992 ls.print_cr("======== FREEZING FRAME interpreted: %d bottom: %d", f.is_interpreted_frame(), is_bottom_frame);
993 ls.print_cr("fsize: %d argsize: %d", fsize, argsize);
994 f.print_value_on(&ls);
995 }
996 assert(caller.is_interpreted_frame() == Interpreter::contains(caller.pc()), "");
997 }
998
999 inline void FreezeBase::after_freeze_java_frame(const frame& hf, bool is_bottom_frame) {
1000 LogTarget(Trace, continuations) lt;
1001 if (lt.develop_is_enabled()) {
1002 LogStream ls(lt);
1003 DEBUG_ONLY(hf.print_value_on(&ls);)
1004 assert(hf.is_heap_frame(), "should be");
1005 DEBUG_ONLY(print_frame_layout(hf, false, &ls);)
1006 if (is_bottom_frame) {
1007 ls.print_cr("bottom h-frame:");
1008 hf.print_on(&ls);
1009 }
1010 }
1011 }
1012
1013 // The parameter argsize_md includes metadata that has to be part of caller/callee overlap.
1014 // See also StackChunkFrameStream<frame_kind>::frame_size()
1015 freeze_result FreezeBase::finalize_freeze(const frame& callee, frame& caller, int argsize_md) {
1016 int argsize = argsize_md - frame::metadata_words_at_top;
1017 assert(callee.is_interpreted_frame()
1018 || ContinuationHelper::Frame::is_stub(callee.cb())
1019 || callee.cb()->as_nmethod()->is_osr_method()
1020 || argsize == _cont.argsize(), "argsize: %d cont.argsize: %d", argsize, _cont.argsize());
1021 log_develop_trace(continuations)("bottom: " INTPTR_FORMAT " count %d size: %d argsize: %d",
1022 p2i(_bottom_address), _frames, _freeze_size << LogBytesPerWord, argsize);
1023
1024 LogTarget(Trace, continuations) lt;
1025
1026 #ifdef ASSERT
1027 bool empty = _cont.is_empty();
1028 log_develop_trace(continuations)("empty: %d", empty);
1029 #endif
1030
1031 stackChunkOop chunk = _cont.tail();
1032
1033 assert(chunk == nullptr || (chunk->max_thawing_size() == 0) == chunk->is_empty(), "");
1034
1035 _freeze_size += frame::metadata_words; // for top frame's metadata
1036
1037 int overlap = 0; // the args overlap the caller -- if there is one in this chunk and is of the same kind
1038 int unextended_sp = -1;
1039 if (chunk != nullptr) {
1040 if (!chunk->is_empty()) {
1041 StackChunkFrameStream<ChunkFrames::Mixed> last(chunk);
1042 unextended_sp = chunk->to_offset(StackChunkFrameStream<ChunkFrames::Mixed>(chunk).unextended_sp());
1043 bool top_interpreted = Interpreter::contains(chunk->pc());
1044 if (callee.is_interpreted_frame() == top_interpreted) {
1045 overlap = argsize_md;
1046 }
1047 } else {
1048 unextended_sp = chunk->stack_size() - frame::metadata_words_at_top;
1049 }
1050 }
1051
1052 log_develop_trace(continuations)("finalize _size: %d overlap: %d unextended_sp: %d", _freeze_size, overlap, unextended_sp);
1053
1054 _freeze_size -= overlap;
1055 assert(_freeze_size >= 0, "");
1056
1057 assert(chunk == nullptr || chunk->is_empty()
1058 || unextended_sp == chunk->to_offset(StackChunkFrameStream<ChunkFrames::Mixed>(chunk).unextended_sp()), "");
1059 assert(chunk != nullptr || unextended_sp < _freeze_size, "");
1060
1061 _freeze_size += _monitors_in_lockstack;
1062
1063 // _barriers can be set to true by an allocation in freeze_fast, in which case the chunk is available
1064 bool allocated_old_in_freeze_fast = _barriers;
1065 assert(!allocated_old_in_freeze_fast || (unextended_sp >= _freeze_size && chunk->is_empty()),
1066 "Chunk allocated in freeze_fast is of insufficient size "
1067 "unextended_sp: %d size: %d is_empty: %d", unextended_sp, _freeze_size, chunk->is_empty());
1068 assert(!allocated_old_in_freeze_fast || (!UseZGC && !UseG1GC), "Unexpected allocation");
1069
1070 DEBUG_ONLY(bool empty_chunk = true);
1071 if (unextended_sp < _freeze_size || chunk->is_gc_mode() || (!allocated_old_in_freeze_fast && chunk->requires_barriers())) {
1072 // ALLOCATE NEW CHUNK
1073
1074 if (lt.develop_is_enabled()) {
1075 LogStream ls(lt);
1076 if (chunk == nullptr) {
1077 ls.print_cr("no chunk");
1078 } else {
1079 ls.print_cr("chunk barriers: %d _size: %d free size: %d",
1080 chunk->requires_barriers(), _freeze_size, chunk->sp() - frame::metadata_words);
1081 chunk->print_on(&ls);
1082 }
1083 }
1084
1085 _freeze_size += overlap; // we're allocating a new chunk, so no overlap
1086 // overlap = 0;
1087
1088 chunk = allocate_chunk_slow(_freeze_size, argsize_md);
1089 if (chunk == nullptr) {
1090 return freeze_exception;
1091 }
1092
1093 // Install new chunk
1094 _cont.set_tail(chunk);
1095 assert(chunk->is_empty(), "");
1096 } else {
1097 // REUSE EXISTING CHUNK
1098 log_develop_trace(continuations)("Reusing chunk mixed: %d empty: %d", chunk->has_mixed_frames(), chunk->is_empty());
1099 if (chunk->is_empty()) {
1100 int sp = chunk->stack_size() - argsize_md;
1101 chunk->set_sp(sp);
1102 chunk->set_bottom(sp);
1103 _freeze_size += overlap;
1104 assert(chunk->max_thawing_size() == 0, "");
1105 } DEBUG_ONLY(else empty_chunk = false;)
1106 }
1107 assert(!chunk->is_gc_mode(), "");
1108 assert(!chunk->has_bitmap(), "");
1109 chunk->set_has_mixed_frames(true);
1110
1111 assert(chunk->requires_barriers() == _barriers, "");
1112 assert(!_barriers || chunk->is_empty(), "");
1113
1114 assert(!chunk->is_empty() || StackChunkFrameStream<ChunkFrames::Mixed>(chunk).is_done(), "");
1115 assert(!chunk->is_empty() || StackChunkFrameStream<ChunkFrames::Mixed>(chunk).to_frame().is_empty(), "");
1116
1117 if (_preempt) {
1118 frame f = _thread->last_frame();
1119 if (f.is_interpreted_frame()) {
1120 // Some platforms do not save the last_sp in the top interpreter frame on VM calls.
1121 // We need it so that on resume we can restore the sp to the right place, since
1122 // thawing might add an alignment word to the expression stack (see finish_thaw()).
1123 // We do it now that we know freezing will be successful.
1124 prepare_freeze_interpreted_top_frame(f);
1125 }
1126 }
1127
1128 // We unwind frames after the last safepoint so that the GC will have found the oops in the frames, but before
1129 // writing into the chunk. This is so that an asynchronous stack walk (not at a safepoint) that suspends us here
1130 // will either see no continuation or a consistent chunk.
1131 unwind_frames();
1132
1133 chunk->set_max_thawing_size(chunk->max_thawing_size() + _freeze_size - _monitors_in_lockstack - frame::metadata_words);
1134
1135 if (lt.develop_is_enabled()) {
1136 LogStream ls(lt);
1137 ls.print_cr("top chunk:");
1138 chunk->print_on(&ls);
1139 }
1140
1141 if (_monitors_in_lockstack > 0) {
1142 freeze_lockstack(chunk);
1143 }
1144
1145 // The topmost existing frame in the chunk; or an empty frame if the chunk is empty
1146 caller = StackChunkFrameStream<ChunkFrames::Mixed>(chunk).to_frame();
1147
1148 DEBUG_ONLY(_last_write = caller.unextended_sp() + (empty_chunk ? argsize_md : overlap);)
1149
1150 assert(chunk->is_in_chunk(_last_write - _freeze_size),
1151 "last_write-size: " INTPTR_FORMAT " start: " INTPTR_FORMAT, p2i(_last_write-_freeze_size), p2i(chunk->start_address()));
1152 #ifdef ASSERT
1153 if (lt.develop_is_enabled()) {
1154 LogStream ls(lt);
1155 ls.print_cr("top hframe before (freeze):");
1156 assert(caller.is_heap_frame(), "should be");
1157 caller.print_on(&ls);
1158 }
1159
1160 assert(!empty || Continuation::is_continuation_entry_frame(callee, nullptr), "");
1161
1162 frame entry = sender(callee);
1163
1164 assert((!empty && Continuation::is_return_barrier_entry(entry.pc())) || (empty && Continuation::is_continuation_enterSpecial(entry)), "");
1165 assert(callee.is_interpreted_frame() || entry.sp() == entry.unextended_sp(), "");
1166 #endif
1167
1168 return freeze_ok_bottom;
1169 }
1170
1171 // After freezing a frame we need to possibly adjust some values related to the caller frame.
1172 void FreezeBase::patch(const frame& f, frame& hf, const frame& caller, bool is_bottom_frame) {
1173 if (is_bottom_frame) {
1174 // If we're the bottom frame, we need to replace the return barrier with the real
1175 // caller's pc.
1176 address last_pc = caller.pc();
1177 assert((last_pc == nullptr) == _cont.tail()->is_empty(), "");
1178 ContinuationHelper::Frame::patch_pc(caller, last_pc);
1179 } else {
1180 assert(!caller.is_empty(), "");
1181 }
1182
1183 patch_pd(hf, caller, is_bottom_frame);
1184
1185 if (f.is_interpreted_frame()) {
1186 assert(hf.is_heap_frame(), "should be");
1187 ContinuationHelper::InterpretedFrame::patch_sender_sp(hf, caller);
1188 }
1189
1190 #ifdef ASSERT
1191 if (hf.is_compiled_frame()) {
1192 if (f.is_deoptimized_frame()) { // TODO DEOPT: long term solution: unroll on freeze and patch pc
1193 log_develop_trace(continuations)("Freezing deoptimized frame");
1194 assert(f.cb()->as_nmethod()->is_deopt_pc(f.raw_pc()), "");
1195 assert(f.cb()->as_nmethod()->is_deopt_pc(ContinuationHelper::Frame::real_pc(f)), "");
1196 }
1197 }
1198 #endif
1199 }
1200
1201 #ifdef ASSERT
1202 static void verify_frame_top(const frame& f, intptr_t* top) {
1203 ResourceMark rm;
1204 InterpreterOopMap mask;
1205 f.interpreted_frame_oop_map(&mask);
1206 assert(top <= ContinuationHelper::InterpretedFrame::frame_top(f, &mask),
1207 "frame_top: " INTPTR_FORMAT " Interpreted::frame_top: " INTPTR_FORMAT,
1208 p2i(top), p2i(ContinuationHelper::InterpretedFrame::frame_top(f, &mask)));
1209 }
1210 #endif // ASSERT
1211
1212 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
1213 // See also StackChunkFrameStream<frame_kind>::frame_size()
1214 NOINLINE freeze_result FreezeBase::recurse_freeze_interpreted_frame(frame& f, frame& caller,
1215 int callee_argsize /* incl. metadata */,
1216 bool callee_interpreted) {
1217 adjust_interpreted_frame_unextended_sp(f);
1218
1219 // The frame's top never includes the stack arguments to the callee
1220 intptr_t* const stack_frame_top = ContinuationHelper::InterpretedFrame::frame_top(f, callee_argsize, callee_interpreted);
1221 intptr_t* const stack_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(f);
1222 const int fsize = pointer_delta_as_int(stack_frame_bottom, stack_frame_top);
1223
1224 DEBUG_ONLY(verify_frame_top(f, stack_frame_top));
1225
1226 Method* frame_method = ContinuationHelper::Frame::frame_method(f);
1227 // including metadata between f and its args
1228 const int argsize = ContinuationHelper::InterpretedFrame::stack_argsize(f) + frame::metadata_words_at_top;
1229
1230 log_develop_trace(continuations)("recurse_freeze_interpreted_frame %s _size: %d fsize: %d argsize: %d callee_interpreted: %d",
1231 frame_method->name_and_sig_as_C_string(), _freeze_size, fsize, argsize, callee_interpreted);
1232 // we'd rather not yield inside methods annotated with @JvmtiMountTransition
1233 assert(!ContinuationHelper::Frame::frame_method(f)->jvmti_mount_transition(), "");
1234
1235 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::InterpretedFrame>(f, caller, fsize, argsize);
1236 if (UNLIKELY(result > freeze_ok_bottom)) {
1237 return result;
1238 }
1239
1240 bool is_bottom_frame = result == freeze_ok_bottom;
1241 assert(!caller.is_empty() || is_bottom_frame, "");
1242
1243 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, 0, is_bottom_frame);)
1244
1245 frame hf = new_heap_frame<ContinuationHelper::InterpretedFrame>(f, caller);
1246 _total_align_size += frame::align_wiggle; // add alignment room for internal interpreted frame alignment on AArch64/PPC64
1247
1248 intptr_t* heap_frame_top = ContinuationHelper::InterpretedFrame::frame_top(hf, callee_argsize, callee_interpreted);
1249 intptr_t* heap_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(hf);
1250 assert(heap_frame_bottom == heap_frame_top + fsize, "");
1251
1252 // Some architectures (like AArch64/PPC64/RISC-V) add padding between the locals and the fixed_frame to keep the fp 16-byte-aligned.
1253 // On those architectures we freeze the padding in order to keep the same fp-relative offsets in the fixed_frame.
1254 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1255 assert(!is_bottom_frame || !caller.is_interpreted_frame() || (heap_frame_top + fsize) == (caller.unextended_sp() + argsize), "");
1256
1257 relativize_interpreted_frame_metadata(f, hf);
1258
1259 patch(f, hf, caller, is_bottom_frame);
1260
1261 CONT_JFR_ONLY(_jfr_info.record_interpreted_frame();)
1262 DEBUG_ONLY(after_freeze_java_frame(hf, is_bottom_frame);)
1263 caller = hf;
1264
1265 // Mark frame_method's GC epoch for class redefinition on_stack calculation.
1266 frame_method->record_gc_epoch();
1267
1268 return freeze_ok;
1269 }
1270
1271 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
1272 // See also StackChunkFrameStream<frame_kind>::frame_size()
1273 freeze_result FreezeBase::recurse_freeze_compiled_frame(frame& f, frame& caller,
1274 int callee_argsize /* incl. metadata */,
1275 bool callee_interpreted) {
1276 // The frame's top never includes the stack arguments to the callee
1277 intptr_t* const stack_frame_top = ContinuationHelper::CompiledFrame::frame_top(f, callee_argsize, callee_interpreted);
1278 intptr_t* const stack_frame_bottom = ContinuationHelper::CompiledFrame::frame_bottom(f);
1279 // including metadata between f and its stackargs
1280 int argsize = ContinuationHelper::CompiledFrame::stack_argsize(f) + frame::metadata_words_at_top;
1281 int fsize = pointer_delta_as_int(stack_frame_bottom + argsize, stack_frame_top);
1282
1283 int real_frame_size = 0;
1284 bool augmented = f.was_augmented_on_entry(real_frame_size);
1285 if (augmented) {
1286 // The args reside inside the frame so clear argsize. If the caller is compiled,
1287 // this will cause the stack arguments passed by the caller to be freezed when
1288 // freezing the caller frame itself. If the caller is interpreted this will have
1289 // the effect of discarding the arg area created in the i2c stub.
1290 argsize = 0;
1291 fsize = real_frame_size - (callee_interpreted ? 0 : callee_argsize);
1292 #ifdef ASSERT
1293 nmethod* nm = f.cb()->as_nmethod();
1294 Method* method = nm->method();
1295 address return_pc = ContinuationHelper::CompiledFrame::return_pc(f);
1296 CodeBlob* caller_cb = CodeCache::find_blob_fast(return_pc);
1297 assert(nm->is_compiled_by_c2() || (caller_cb->is_nmethod() && caller_cb->as_nmethod()->is_compiled_by_c2()), "caller or callee should be c2 compiled");
1298 assert((!caller_cb->is_nmethod() && nm->is_compiled_by_c2()) ||
1299 (nm->compiler_type() != caller_cb->as_nmethod()->compiler_type()) ||
1300 (nm->is_compiled_by_c2() && !method->is_static() && method->method_holder()->is_inline_klass()),
1301 "frame should not be extended");
1302 #endif
1303 }
1304
1305 log_develop_trace(continuations)("recurse_freeze_compiled_frame %s _size: %d fsize: %d argsize: %d augmented: %d",
1306 ContinuationHelper::Frame::frame_method(f) != nullptr ?
1307 ContinuationHelper::Frame::frame_method(f)->name_and_sig_as_C_string() : "",
1308 _freeze_size, fsize, argsize, augmented);
1309 // we'd rather not yield inside methods annotated with @JvmtiMountTransition
1310 assert(!ContinuationHelper::Frame::frame_method(f)->jvmti_mount_transition(), "");
1311
1312 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::CompiledFrame>(f, caller, fsize, argsize);
1313 if (UNLIKELY(result > freeze_ok_bottom)) {
1314 return result;
1315 }
1316
1317 bool is_bottom_frame = result == freeze_ok_bottom;
1318 assert(!caller.is_empty() || is_bottom_frame, "");
1319 assert(!is_bottom_frame || !augmented, "thaw extended frame without caller?");
1320
1321 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, argsize, is_bottom_frame);)
1322
1323 frame hf = new_heap_frame<ContinuationHelper::CompiledFrame>(f, caller, augmented ? real_frame_size - f.cb()->as_nmethod()->frame_size() : 0);
1324
1325 intptr_t* heap_frame_top = ContinuationHelper::CompiledFrame::frame_top(hf, callee_argsize, callee_interpreted);
1326
1327 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1328 assert(!is_bottom_frame || !caller.is_compiled_frame() || (heap_frame_top + fsize) == (caller.unextended_sp() + argsize), "");
1329
1330 if (caller.is_interpreted_frame()) {
1331 // When thawing the frame we might need to add alignment (see Thaw::align)
1332 _total_align_size += frame::align_wiggle;
1333 }
1334
1335 patch(f, hf, caller, is_bottom_frame);
1336
1337 assert(is_bottom_frame || Interpreter::contains(ContinuationHelper::CompiledFrame::real_pc(caller)) == caller.is_interpreted_frame(), "");
1338
1339 DEBUG_ONLY(after_freeze_java_frame(hf, is_bottom_frame);)
1340 caller = hf;
1341 return freeze_ok;
1342 }
1343
1344 NOINLINE freeze_result FreezeBase::recurse_freeze_stub_frame(frame& f, frame& caller) {
1345 DEBUG_ONLY(frame fsender = sender(f);)
1346 assert(fsender.is_compiled_frame(), "sender should be compiled frame");
1347
1348 intptr_t* const stack_frame_top = ContinuationHelper::StubFrame::frame_top(f);
1349 const int fsize = f.cb()->frame_size();
1350
1351 log_develop_trace(continuations)("recurse_freeze_stub_frame %s _size: %d fsize: %d :: " INTPTR_FORMAT " - " INTPTR_FORMAT,
1352 f.cb()->name(), _freeze_size, fsize, p2i(stack_frame_top), p2i(stack_frame_top+fsize));
1353
1354 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::StubFrame>(f, caller, fsize, 0);
1355 if (UNLIKELY(result > freeze_ok_bottom)) {
1356 return result;
1357 }
1358
1359 assert(result == freeze_ok, "should have caller");
1360 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, 0, false /*is_bottom_frame*/);)
1361
1362 frame hf = new_heap_frame<ContinuationHelper::StubFrame>(f, caller);
1363 intptr_t* heap_frame_top = ContinuationHelper::StubFrame::frame_top(hf);
1364
1365 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1366
1367 patch(f, hf, caller, false /*is_bottom_frame*/);
1368
1369 DEBUG_ONLY(after_freeze_java_frame(hf, false /*is_bottom_frame*/);)
1370
1371 caller = hf;
1372 return freeze_ok;
1373 }
1374
1375 NOINLINE freeze_result FreezeBase::recurse_freeze_native_frame(frame& f, frame& caller) {
1376 if (!f.cb()->as_nmethod()->method()->is_object_wait0()) {
1377 assert(f.cb()->as_nmethod()->method()->is_synchronized(), "");
1378 // Synchronized native method case. Unlike the interpreter native wrapper, the compiled
1379 // native wrapper tries to acquire the monitor after marshalling the arguments from the
1380 // caller into the native convention. This is so that we have a valid oopMap in case of
1381 // having to block in the slow path. But that would require freezing those registers too
1382 // and then fixing them back on thaw in case of oops. To avoid complicating things and
1383 // given that this would be a rare case anyways just pin the vthread to the carrier.
1384 return freeze_pinned_native;
1385 }
1386
1387 intptr_t* const stack_frame_top = ContinuationHelper::NativeFrame::frame_top(f);
1388 // There are no stackargs but argsize must include the metadata
1389 const int argsize = frame::metadata_words_at_top;
1390 const int fsize = f.cb()->frame_size() + argsize;
1391
1392 log_develop_trace(continuations)("recurse_freeze_native_frame %s _size: %d fsize: %d :: " INTPTR_FORMAT " - " INTPTR_FORMAT,
1393 f.cb()->name(), _freeze_size, fsize, p2i(stack_frame_top), p2i(stack_frame_top+fsize));
1394
1395 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::NativeFrame>(f, caller, fsize, argsize);
1396 if (UNLIKELY(result > freeze_ok_bottom)) {
1397 return result;
1398 }
1399
1400 assert(result == freeze_ok, "should have caller frame");
1401 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, argsize, false /* is_bottom_frame */);)
1402
1403 frame hf = new_heap_frame<ContinuationHelper::NativeFrame>(f, caller);
1404 intptr_t* heap_frame_top = ContinuationHelper::NativeFrame::frame_top(hf);
1405
1406 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1407
1408 if (caller.is_interpreted_frame()) {
1409 // When thawing the frame we might need to add alignment (see Thaw::align)
1410 _total_align_size += frame::align_wiggle;
1411 }
1412
1413 patch(f, hf, caller, false /* is_bottom_frame */);
1414
1415 DEBUG_ONLY(after_freeze_java_frame(hf, false /* is_bottom_frame */);)
1416
1417 caller = hf;
1418 return freeze_ok;
1419 }
1420
1421 NOINLINE void FreezeBase::finish_freeze(const frame& f, const frame& top) {
1422 stackChunkOop chunk = _cont.tail();
1423
1424 LogTarget(Trace, continuations) lt;
1425 if (lt.develop_is_enabled()) {
1426 LogStream ls(lt);
1427 assert(top.is_heap_frame(), "should be");
1428 top.print_on(&ls);
1429 }
1430
1431 set_top_frame_metadata_pd(top);
1432
1433 chunk->set_sp(chunk->to_offset(top.sp()));
1434 chunk->set_pc(top.pc());
1435
1436 chunk->set_max_thawing_size(chunk->max_thawing_size() + _total_align_size);
1437
1438 assert(chunk->sp_address() - chunk->start_address() >= _monitors_in_lockstack, "clash with lockstack");
1439
1440 // At this point the chunk is consistent
1441
1442 if (UNLIKELY(_barriers)) {
1443 log_develop_trace(continuations)("do barriers on old chunk");
1444 // Serial and Parallel GC can allocate objects directly into the old generation.
1445 // Then we want to relativize the derived pointers eagerly so that
1446 // old chunks are all in GC mode.
1447 assert(!UseG1GC, "G1 can not deal with allocating outside of eden");
1448 assert(!UseZGC, "ZGC can not deal with allocating chunks visible to marking");
1449 if (UseShenandoahGC) {
1450 _cont.tail()->relativize_derived_pointers_concurrently();
1451 } else {
1452 ContinuationGCSupport::transform_stack_chunk(_cont.tail());
1453 }
1454 // For objects in the old generation we must maintain the remembered set
1455 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>();
1456 }
1457
1458 log_develop_trace(continuations)("finish_freeze: has_mixed_frames: %d", chunk->has_mixed_frames());
1459 if (lt.develop_is_enabled()) {
1460 LogStream ls(lt);
1461 chunk->print_on(true, &ls);
1462 }
1463
1464 if (lt.develop_is_enabled()) {
1465 LogStream ls(lt);
1466 ls.print_cr("top hframe after (freeze):");
1467 assert(_cont.last_frame().is_heap_frame(), "should be");
1468 _cont.last_frame().print_on(&ls);
1469 DEBUG_ONLY(print_frame_layout(top, false, &ls);)
1470 }
1471
1472 assert(_cont.chunk_invariant(), "");
1473 }
1474
1475 inline bool FreezeBase::stack_overflow() { // detect stack overflow in recursive native code
1476 JavaThread* t = !_preempt ? _thread : JavaThread::current();
1477 assert(t == JavaThread::current(), "");
1478 if (os::current_stack_pointer() < t->stack_overflow_state()->shadow_zone_safe_limit()) {
1479 if (!_preempt) {
1480 ContinuationWrapper::SafepointOp so(t, _cont); // could also call _cont.done() instead
1481 Exceptions::_throw_msg(t, __FILE__, __LINE__, vmSymbols::java_lang_StackOverflowError(), "Stack overflow while freezing");
1482 }
1483 return true;
1484 }
1485 return false;
1486 }
1487
1488 class StackChunkAllocator : public MemAllocator {
1489 const size_t _stack_size;
1490 int _argsize_md;
1491 ContinuationWrapper& _continuation_wrapper;
1492 JvmtiSampledObjectAllocEventCollector* const _jvmti_event_collector;
1493 mutable bool _took_slow_path;
1494
1495 // Does the minimal amount of initialization needed for a TLAB allocation.
1496 // We don't need to do a full initialization, as such an allocation need not be immediately walkable.
1497 virtual oop initialize(HeapWord* mem) const override {
1498 assert(_stack_size > 0, "");
1499 assert(_stack_size <= max_jint, "");
1500 assert(_word_size > _stack_size, "");
1501
1502 // zero out fields (but not the stack)
1503 const size_t hs = oopDesc::header_size();
1504 if (oopDesc::has_klass_gap()) {
1505 oopDesc::set_klass_gap(mem, 0);
1506 }
1507 Copy::fill_to_aligned_words(mem + hs, vmClasses::StackChunk_klass()->size_helper() - hs);
1508
1509 int bottom = (int)_stack_size - _argsize_md;
1510
1511 jdk_internal_vm_StackChunk::set_size(mem, (int)_stack_size);
1512 jdk_internal_vm_StackChunk::set_bottom(mem, bottom);
1513 jdk_internal_vm_StackChunk::set_sp(mem, bottom);
1514
1515 return finish(mem);
1516 }
1517
1518 stackChunkOop allocate_fast() const {
1519 if (!UseTLAB) {
1520 return nullptr;
1521 }
1522
1523 HeapWord* const mem = MemAllocator::mem_allocate_inside_tlab_fast();
1524 if (mem == nullptr) {
1525 return nullptr;
1526 }
1527
1528 oop obj = initialize(mem);
1529 return stackChunkOopDesc::cast(obj);
1530 }
1531
1532 public:
1533 StackChunkAllocator(Klass* klass,
1534 size_t word_size,
1535 Thread* thread,
1536 size_t stack_size,
1537 int argsize_md,
1538 ContinuationWrapper& continuation_wrapper,
1539 JvmtiSampledObjectAllocEventCollector* jvmti_event_collector)
1540 : MemAllocator(klass, word_size, thread),
1541 _stack_size(stack_size),
1542 _argsize_md(argsize_md),
1543 _continuation_wrapper(continuation_wrapper),
1544 _jvmti_event_collector(jvmti_event_collector),
1545 _took_slow_path(false) {}
1546
1547 // Provides it's own, specialized allocation which skips instrumentation
1548 // if the memory can be allocated without going to a slow-path.
1549 stackChunkOop allocate() const {
1550 // First try to allocate without any slow-paths or instrumentation.
1551 stackChunkOop obj = allocate_fast();
1552 if (obj != nullptr) {
1553 return obj;
1554 }
1555
1556 // Now try full-blown allocation with all expensive operations,
1557 // including potentially safepoint operations.
1558 _took_slow_path = true;
1559
1560 // Protect unhandled Loom oops
1561 ContinuationWrapper::SafepointOp so(_thread, _continuation_wrapper);
1562
1563 // Can safepoint
1564 _jvmti_event_collector->start();
1565
1566 // Can safepoint
1567 return stackChunkOopDesc::cast(MemAllocator::allocate());
1568 }
1569
1570 bool took_slow_path() const {
1571 return _took_slow_path;
1572 }
1573 };
1574
1575 template <typename ConfigT>
1576 stackChunkOop Freeze<ConfigT>::allocate_chunk(size_t stack_size, int argsize_md) {
1577 log_develop_trace(continuations)("allocate_chunk allocating new chunk");
1578
1579 InstanceStackChunkKlass* klass = InstanceStackChunkKlass::cast(vmClasses::StackChunk_klass());
1580 size_t size_in_words = klass->instance_size(stack_size);
1581
1582 if (CollectedHeap::stack_chunk_max_size() > 0 && size_in_words >= CollectedHeap::stack_chunk_max_size()) {
1583 if (!_preempt) {
1584 throw_stack_overflow_on_humongous_chunk();
1585 }
1586 return nullptr;
1587 }
1588
1589 JavaThread* current = _preempt ? JavaThread::current() : _thread;
1590 assert(current == JavaThread::current(), "should be current");
1591
1592 // Allocate the chunk.
1593 //
1594 // This might safepoint while allocating, but all safepointing due to
1595 // instrumentation have been deferred. This property is important for
1596 // some GCs, as this ensures that the allocated object is in the young
1597 // generation / newly allocated memory.
1598 StackChunkAllocator allocator(klass, size_in_words, current, stack_size, argsize_md, _cont, _jvmti_event_collector);
1599 stackChunkOop chunk = allocator.allocate();
1600
1601 if (chunk == nullptr) {
1602 return nullptr; // OOME
1603 }
1604
1605 // assert that chunk is properly initialized
1606 assert(chunk->stack_size() == (int)stack_size, "");
1607 assert(chunk->size() >= stack_size, "chunk->size(): %zu size: %zu", chunk->size(), stack_size);
1608 assert(chunk->sp() == chunk->bottom(), "");
1609 assert((intptr_t)chunk->start_address() % 8 == 0, "");
1610 assert(chunk->max_thawing_size() == 0, "");
1611 assert(chunk->pc() == nullptr, "");
1612 assert(chunk->is_empty(), "");
1613 assert(chunk->flags() == 0, "");
1614 assert(chunk->is_gc_mode() == false, "");
1615 assert(chunk->lockstack_size() == 0, "");
1616
1617 // fields are uninitialized
1618 chunk->set_parent_access<IS_DEST_UNINITIALIZED>(_cont.last_nonempty_chunk());
1619 chunk->set_cont_access<IS_DEST_UNINITIALIZED>(_cont.continuation());
1620
1621 #if INCLUDE_ZGC
1622 if (UseZGC) {
1623 ZStackChunkGCData::initialize(chunk);
1624 assert(!chunk->requires_barriers(), "ZGC always allocates in the young generation");
1625 _barriers = false;
1626 } else
1627 #endif
1628 #if INCLUDE_SHENANDOAHGC
1629 if (UseShenandoahGC) {
1630 _barriers = chunk->requires_barriers();
1631 } else
1632 #endif
1633 {
1634 if (!allocator.took_slow_path()) {
1635 // Guaranteed to be in young gen / newly allocated memory
1636 assert(!chunk->requires_barriers(), "Unfamiliar GC requires barriers on TLAB allocation");
1637 _barriers = false;
1638 } else {
1639 // Some GCs could put direct allocations in old gen for slow-path
1640 // allocations; need to explicitly check if that was the case.
1641 _barriers = chunk->requires_barriers();
1642 }
1643 }
1644
1645 if (_barriers) {
1646 log_develop_trace(continuations)("allocation requires barriers");
1647 }
1648
1649 assert(chunk->parent() == nullptr || chunk->parent()->is_stackChunk(), "");
1650
1651 return chunk;
1652 }
1653
1654 void FreezeBase::throw_stack_overflow_on_humongous_chunk() {
1655 ContinuationWrapper::SafepointOp so(_thread, _cont); // could also call _cont.done() instead
1656 Exceptions::_throw_msg(_thread, __FILE__, __LINE__, vmSymbols::java_lang_StackOverflowError(), "Humongous stack chunk");
1657 }
1658
1659 #if INCLUDE_JVMTI
1660 static int num_java_frames(ContinuationWrapper& cont) {
1661 ResourceMark rm; // used for scope traversal in num_java_frames(nmethod*, address)
1662 int count = 0;
1663 for (stackChunkOop chunk = cont.tail(); chunk != nullptr; chunk = chunk->parent()) {
1664 count += chunk->num_java_frames();
1665 }
1666 return count;
1667 }
1668
1669 static void invalidate_jvmti_stack(JavaThread* thread) {
1670 if (thread->is_interp_only_mode()) {
1671 JvmtiThreadState *state = thread->jvmti_thread_state();
1672 if (state != nullptr)
1673 state->invalidate_cur_stack_depth();
1674 }
1675 }
1676
1677 static void jvmti_yield_cleanup(JavaThread* thread, ContinuationWrapper& cont) {
1678 if (JvmtiExport::can_post_frame_pop()) {
1679 int num_frames = num_java_frames(cont);
1680
1681 ContinuationWrapper::SafepointOp so(Thread::current(), cont);
1682 JvmtiExport::continuation_yield_cleanup(JavaThread::current(), num_frames);
1683 }
1684 invalidate_jvmti_stack(thread);
1685 }
1686
1687 static void jvmti_mount_end(JavaThread* current, ContinuationWrapper& cont, frame top) {
1688 assert(current->vthread() != nullptr, "must be");
1689
1690 HandleMarkCleaner hm(current);
1691 Handle vth(current, current->vthread());
1692
1693 ContinuationWrapper::SafepointOp so(current, cont);
1694
1695 // Since we might safepoint set the anchor so that the stack can be walked.
1696 set_anchor(current, top.sp());
1697
1698 JRT_BLOCK
1699 JvmtiVTMSTransitionDisabler::VTMS_vthread_mount((jthread)vth.raw_value(), false);
1700
1701 if (current->pending_contended_entered_event()) {
1702 JvmtiExport::post_monitor_contended_entered(current, current->contended_entered_monitor());
1703 current->set_contended_entered_monitor(nullptr);
1704 }
1705 JRT_BLOCK_END
1706
1707 clear_anchor(current);
1708 }
1709 #endif // INCLUDE_JVMTI
1710
1711 #ifdef ASSERT
1712 // There are no interpreted frames if we're not called from the interpreter and we haven't ancountered an i2c
1713 // adapter or called Deoptimization::unpack_frames. As for native frames, upcalls from JNI also go through the
1714 // interpreter (see JavaCalls::call_helper), while the UpcallLinker explicitly sets cont_fastpath.
1715 bool FreezeBase::check_valid_fast_path() {
1716 ContinuationEntry* ce = _thread->last_continuation();
1717 RegisterMap map(_thread,
1718 RegisterMap::UpdateMap::skip,
1719 RegisterMap::ProcessFrames::skip,
1720 RegisterMap::WalkContinuation::skip);
1721 map.set_include_argument_oops(false);
1722 bool is_top_frame = true;
1723 for (frame f = freeze_start_frame(); Continuation::is_frame_in_continuation(ce, f); f = f.sender(&map), is_top_frame = false) {
1724 if (!((f.is_compiled_frame() && !f.is_deoptimized_frame()) || (is_top_frame && (f.is_runtime_frame() || f.is_native_frame())))) {
1725 return false;
1726 }
1727 }
1728 return true;
1729 }
1730 #endif // ASSERT
1731
1732 static inline freeze_result freeze_epilog(ContinuationWrapper& cont) {
1733 verify_continuation(cont.continuation());
1734 assert(!cont.is_empty(), "");
1735
1736 log_develop_debug(continuations)("=== End of freeze cont ### #" INTPTR_FORMAT, cont.hash());
1737 return freeze_ok;
1738 }
1739
1740 static freeze_result freeze_epilog(JavaThread* thread, ContinuationWrapper& cont, freeze_result res) {
1741 if (UNLIKELY(res != freeze_ok)) {
1742 JFR_ONLY(thread->set_last_freeze_fail_result(res);)
1743 verify_continuation(cont.continuation());
1744 log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1745 return res;
1746 }
1747
1748 JVMTI_ONLY(jvmti_yield_cleanup(thread, cont)); // can safepoint
1749 return freeze_epilog(cont);
1750 }
1751
1752 static freeze_result preempt_epilog(ContinuationWrapper& cont, freeze_result res, frame& old_last_frame) {
1753 if (UNLIKELY(res != freeze_ok)) {
1754 verify_continuation(cont.continuation());
1755 log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1756 return res;
1757 }
1758
1759 patch_return_pc_with_preempt_stub(old_last_frame);
1760 cont.tail()->set_preempted(true);
1761
1762 return freeze_epilog(cont);
1763 }
1764
1765 template<typename ConfigT, bool preempt>
1766 static inline freeze_result freeze_internal(JavaThread* current, intptr_t* const sp) {
1767 assert(!current->has_pending_exception(), "");
1768
1769 #ifdef ASSERT
1770 log_trace(continuations)("~~~~ freeze sp: " INTPTR_FORMAT "JavaThread: " INTPTR_FORMAT, p2i(current->last_continuation()->entry_sp()), p2i(current));
1771 log_frames(current);
1772 #endif
1773
1774 CONT_JFR_ONLY(EventContinuationFreeze event;)
1775
1776 ContinuationEntry* entry = current->last_continuation();
1777
1778 oop oopCont = entry->cont_oop(current);
1779 assert(oopCont == current->last_continuation()->cont_oop(current), "");
1780 assert(ContinuationEntry::assert_entry_frame_laid_out(current), "");
1781
1782 verify_continuation(oopCont);
1783 ContinuationWrapper cont(current, oopCont);
1784 log_develop_debug(continuations)("FREEZE #" INTPTR_FORMAT " " INTPTR_FORMAT, cont.hash(), p2i((oopDesc*)oopCont));
1785
1786 assert(entry->is_virtual_thread() == (entry->scope(current) == java_lang_VirtualThread::vthread_scope()), "");
1787
1788 assert(LockingMode == LM_LEGACY || (current->held_monitor_count() == 0 && current->jni_monitor_count() == 0),
1789 "Held monitor count should only be used for LM_LEGACY: " INT64_FORMAT " JNI: " INT64_FORMAT, (int64_t)current->held_monitor_count(), (int64_t)current->jni_monitor_count());
1790
1791 if (entry->is_pinned() || current->held_monitor_count() > 0) {
1792 log_develop_debug(continuations)("PINNED due to critical section/hold monitor");
1793 verify_continuation(cont.continuation());
1794 freeze_result res = entry->is_pinned() ? freeze_pinned_cs : freeze_pinned_monitor;
1795 if (!preempt) {
1796 JFR_ONLY(current->set_last_freeze_fail_result(res);)
1797 }
1798 log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1799 // Avoid Thread.yield() loops without safepoint polls.
1800 if (SafepointMechanism::should_process(current) && !preempt) {
1801 cont.done(); // allow safepoint
1802 ThreadInVMfromJava tivmfj(current);
1803 }
1804 return res;
1805 }
1806
1807 Freeze<ConfigT> freeze(current, cont, sp, preempt);
1808
1809 assert(!current->cont_fastpath() || freeze.check_valid_fast_path(), "");
1810 bool fast = UseContinuationFastPath && current->cont_fastpath();
1811 if (fast && freeze.size_if_fast_freeze_available() > 0) {
1812 freeze.freeze_fast_existing_chunk();
1813 CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1814 return !preempt ? freeze_epilog(cont) : preempt_epilog(cont, freeze_ok, freeze.last_frame());
1815 }
1816
1817 if (preempt) {
1818 JvmtiSampledObjectAllocEventCollector jsoaec(false);
1819 freeze.set_jvmti_event_collector(&jsoaec);
1820
1821 freeze_result res = fast ? freeze.try_freeze_fast() : freeze.freeze_slow();
1822
1823 CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1824 preempt_epilog(cont, res, freeze.last_frame());
1825 return res;
1826 }
1827
1828 log_develop_trace(continuations)("chunk unavailable; transitioning to VM");
1829 assert(current == JavaThread::current(), "must be current thread");
1830 JRT_BLOCK
1831 // delays a possible JvmtiSampledObjectAllocEventCollector in alloc_chunk
1832 JvmtiSampledObjectAllocEventCollector jsoaec(false);
1833 freeze.set_jvmti_event_collector(&jsoaec);
1834
1835 freeze_result res = fast ? freeze.try_freeze_fast() : freeze.freeze_slow();
1836
1837 CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1838 freeze_epilog(current, cont, res);
1839 cont.done(); // allow safepoint in the transition back to Java
1840 return res;
1841 JRT_BLOCK_END
1842 }
1843
1844 static freeze_result is_pinned0(JavaThread* thread, oop cont_scope, bool safepoint) {
1845 ContinuationEntry* entry = thread->last_continuation();
1846 if (entry == nullptr) {
1847 return freeze_ok;
1848 }
1849 if (entry->is_pinned()) {
1850 return freeze_pinned_cs;
1851 } else if (thread->held_monitor_count() > 0) {
1852 return freeze_pinned_monitor;
1853 }
1854
1855 RegisterMap map(thread,
1856 RegisterMap::UpdateMap::include,
1857 RegisterMap::ProcessFrames::skip,
1858 RegisterMap::WalkContinuation::skip);
1859 map.set_include_argument_oops(false);
1860 frame f = thread->last_frame();
1861
1862 if (!safepoint) {
1863 f = f.sender(&map); // this is the yield frame
1864 } else { // safepoint yield
1865 #if (defined(X86) || defined(AARCH64) || defined(RISCV64)) && !defined(ZERO)
1866 f.set_fp(f.real_fp()); // Instead of this, maybe in ContinuationWrapper::set_last_frame always use the real_fp?
1867 #else
1868 Unimplemented();
1869 #endif
1870 if (!Interpreter::contains(f.pc())) {
1871 assert(ContinuationHelper::Frame::is_stub(f.cb()), "must be");
1872 assert(f.oop_map() != nullptr, "must be");
1873 f.oop_map()->update_register_map(&f, &map); // we have callee-save registers in this case
1874 }
1875 }
1876
1877 while (true) {
1878 if ((f.is_interpreted_frame() && f.interpreter_frame_method()->is_native()) || f.is_native_frame()) {
1879 return freeze_pinned_native;
1880 }
1881
1882 f = f.sender(&map);
1883 if (!Continuation::is_frame_in_continuation(entry, f)) {
1884 oop scope = jdk_internal_vm_Continuation::scope(entry->cont_oop(thread));
1885 if (scope == cont_scope) {
1886 break;
1887 }
1888 intx monitor_count = entry->parent_held_monitor_count();
1889 entry = entry->parent();
1890 if (entry == nullptr) {
1891 break;
1892 }
1893 if (entry->is_pinned()) {
1894 return freeze_pinned_cs;
1895 } else if (monitor_count > 0) {
1896 return freeze_pinned_monitor;
1897 }
1898 }
1899 }
1900 return freeze_ok;
1901 }
1902
1903 /////////////// THAW ////
1904
1905 static int thaw_size(stackChunkOop chunk) {
1906 int size = chunk->max_thawing_size();
1907 size += frame::metadata_words; // For the top pc+fp in push_return_frame or top = stack_sp - frame::metadata_words in thaw_fast
1908 size += 2*frame::align_wiggle; // in case of alignments at the top and bottom
1909 return size;
1910 }
1911
1912 // make room on the stack for thaw
1913 // returns the size in bytes, or 0 on failure
1914 static inline int prepare_thaw_internal(JavaThread* thread, bool return_barrier) {
1915 log_develop_trace(continuations)("~~~~ prepare_thaw return_barrier: %d", return_barrier);
1916
1917 assert(thread == JavaThread::current(), "");
1918
1919 ContinuationEntry* ce = thread->last_continuation();
1920 assert(ce != nullptr, "");
1921 oop continuation = ce->cont_oop(thread);
1922 assert(continuation == get_continuation(thread), "");
1923 verify_continuation(continuation);
1924
1925 stackChunkOop chunk = jdk_internal_vm_Continuation::tail(continuation);
1926 assert(chunk != nullptr, "");
1927
1928 // The tail can be empty because it might still be available for another freeze.
1929 // However, here we want to thaw, so we get rid of it (it will be GCed).
1930 if (UNLIKELY(chunk->is_empty())) {
1931 chunk = chunk->parent();
1932 assert(chunk != nullptr, "");
1933 assert(!chunk->is_empty(), "");
1934 jdk_internal_vm_Continuation::set_tail(continuation, chunk);
1935 }
1936
1937 // Verification
1938 chunk->verify();
1939 assert(chunk->max_thawing_size() > 0, "chunk invariant violated; expected to not be empty");
1940
1941 // Only make space for the last chunk because we only thaw from the last chunk
1942 int size = thaw_size(chunk) << LogBytesPerWord;
1943
1944 const address bottom = (address)thread->last_continuation()->entry_sp();
1945 // 300 is an estimate for stack size taken for this native code, in addition to StackShadowPages
1946 // for the Java frames in the check below.
1947 if (!stack_overflow_check(thread, size + 300, bottom)) {
1948 return 0;
1949 }
1950
1951 log_develop_trace(continuations)("prepare_thaw bottom: " INTPTR_FORMAT " top: " INTPTR_FORMAT " size: %d",
1952 p2i(bottom), p2i(bottom - size), size);
1953 return size;
1954 }
1955
1956 class ThawBase : public StackObj {
1957 protected:
1958 JavaThread* _thread;
1959 ContinuationWrapper& _cont;
1960 CONT_JFR_ONLY(FreezeThawJfrInfo _jfr_info;)
1961
1962 intptr_t* _fastpath;
1963 bool _barriers;
1964 bool _preempted_case;
1965 intptr_t* _top_unextended_sp_before_thaw;
1966 int _align_size;
1967 DEBUG_ONLY(intptr_t* _top_stack_address);
1968
1969 StackChunkFrameStream<ChunkFrames::Mixed> _stream;
1970
1971 NOT_PRODUCT(int _frames;)
1972
1973 protected:
1974 ThawBase(JavaThread* thread, ContinuationWrapper& cont) :
1975 _thread(thread), _cont(cont),
1976 _fastpath(nullptr) {
1977 DEBUG_ONLY(_top_unextended_sp_before_thaw = nullptr;)
1978 assert (cont.tail() != nullptr, "no last chunk");
1979 DEBUG_ONLY(_top_stack_address = _cont.entrySP() - thaw_size(cont.tail());)
1980 }
1981
1982 void clear_chunk(stackChunkOop chunk);
1983 template<bool check_stub>
1984 int remove_top_compiled_frame_from_chunk(stackChunkOop chunk, int &argsize);
1985 int remove_scalarized_frames(StackChunkFrameStream<ChunkFrames::CompiledOnly>& scfs, int &argsize);
1986 void copy_from_chunk(intptr_t* from, intptr_t* to, int size);
1987
1988 void thaw_lockstack(stackChunkOop chunk);
1989
1990 // fast path
1991 inline void prefetch_chunk_pd(void* start, int size_words);
1992 void patch_return(intptr_t* sp, bool is_last);
1993
1994 intptr_t* handle_preempted_continuation(intptr_t* sp, Continuation::preempt_kind preempt_kind, bool fast_case);
1995 inline intptr_t* push_cleanup_continuation();
1996 void throw_interrupted_exception(JavaThread* current, frame& top);
1997
1998 void recurse_thaw(const frame& heap_frame, frame& caller, int num_frames, bool top_on_preempt_case);
1999 void finish_thaw(frame& f);
2000
2001 private:
2002 template<typename FKind> bool recurse_thaw_java_frame(frame& caller, int num_frames);
2003 void finalize_thaw(frame& entry, int argsize);
2004
2005 inline bool seen_by_gc();
2006
2007 inline void before_thaw_java_frame(const frame& hf, const frame& caller, bool bottom, int num_frame);
2008 inline void after_thaw_java_frame(const frame& f, bool bottom);
2009 inline void patch(frame& f, const frame& caller, bool bottom, bool augmented = false);
2010 void clear_bitmap_bits(address start, address end);
2011
2012 NOINLINE void recurse_thaw_interpreted_frame(const frame& hf, frame& caller, int num_frames);
2013 void recurse_thaw_compiled_frame(const frame& hf, frame& caller, int num_frames, bool stub_caller);
2014 void recurse_thaw_stub_frame(const frame& hf, frame& caller, int num_frames);
2015 void recurse_thaw_native_frame(const frame& hf, frame& caller, int num_frames);
2016
2017 void push_return_frame(frame& f);
2018 inline frame new_entry_frame();
2019 template<typename FKind> frame new_stack_frame(const frame& hf, frame& caller, bool bottom, int size_adjust = 0);
2020 inline void patch_pd(frame& f, const frame& sender);
2021 inline void patch_pd(frame& f, intptr_t* caller_sp);
2022 inline intptr_t* align(const frame& hf, intptr_t* frame_sp, frame& caller, bool bottom);
2023
2024 void maybe_set_fastpath(intptr_t* sp) { if (sp > _fastpath) _fastpath = sp; }
2025
2026 static inline void derelativize_interpreted_frame_metadata(const frame& hf, const frame& f);
2027
2028 public:
2029 CONT_JFR_ONLY(FreezeThawJfrInfo& jfr_info() { return _jfr_info; })
2030 };
2031
2032 template <typename ConfigT>
2033 class Thaw : public ThawBase {
2034 public:
2035 Thaw(JavaThread* thread, ContinuationWrapper& cont) : ThawBase(thread, cont) {}
2036
2037 inline bool can_thaw_fast(stackChunkOop chunk) {
2038 return !_barriers
2039 && _thread->cont_fastpath_thread_state()
2040 && !chunk->has_thaw_slowpath_condition()
2041 && !PreserveFramePointer;
2042 }
2043
2044 inline intptr_t* thaw(Continuation::thaw_kind kind);
2045 template<bool check_stub = false>
2046 NOINLINE intptr_t* thaw_fast(stackChunkOop chunk);
2047 NOINLINE intptr_t* thaw_slow(stackChunkOop chunk, Continuation::thaw_kind kind);
2048 inline void patch_caller_links(intptr_t* sp, intptr_t* bottom);
2049 };
2050
2051 template <typename ConfigT>
2052 inline intptr_t* Thaw<ConfigT>::thaw(Continuation::thaw_kind kind) {
2053 verify_continuation(_cont.continuation());
2054 assert(!jdk_internal_vm_Continuation::done(_cont.continuation()), "");
2055 assert(!_cont.is_empty(), "");
2056
2057 stackChunkOop chunk = _cont.tail();
2058 assert(chunk != nullptr, "guaranteed by prepare_thaw");
2059 assert(!chunk->is_empty(), "guaranteed by prepare_thaw");
2060
2061 _barriers = chunk->requires_barriers();
2062 return (LIKELY(can_thaw_fast(chunk))) ? thaw_fast(chunk)
2063 : thaw_slow(chunk, kind);
2064 }
2065
2066 class ReconstructedStack : public StackObj {
2067 intptr_t* _base; // _cont.entrySP(); // top of the entry frame
2068 int _thaw_size;
2069 int _argsize;
2070 public:
2071 ReconstructedStack(intptr_t* base, int thaw_size, int argsize)
2072 : _base(base), _thaw_size(thaw_size - (argsize == 0 ? frame::metadata_words_at_top : 0)), _argsize(argsize) {
2073 // The only possible source of misalignment is stack-passed arguments b/c compiled frames are 16-byte aligned.
2074 assert(argsize != 0 || (_base - _thaw_size) == ContinuationHelper::frame_align_pointer(_base - _thaw_size), "");
2075 // We're at most one alignment word away from entrySP
2076 assert(_base - 1 <= top() + total_size() + frame::metadata_words_at_bottom, "missed entry frame");
2077 }
2078
2079 int entry_frame_extension() const { return _argsize + (_argsize > 0 ? frame::metadata_words_at_top : 0); }
2080
2081 // top and bottom stack pointers
2082 intptr_t* sp() const { return ContinuationHelper::frame_align_pointer(_base - _thaw_size); }
2083 intptr_t* bottom_sp() const { return ContinuationHelper::frame_align_pointer(_base - entry_frame_extension()); }
2084
2085 // several operations operate on the totality of the stack being reconstructed,
2086 // including the metadata words
2087 intptr_t* top() const { return sp() - frame::metadata_words_at_bottom; }
2088 int total_size() const { return _thaw_size + frame::metadata_words_at_bottom; }
2089 };
2090
2091 inline void ThawBase::clear_chunk(stackChunkOop chunk) {
2092 chunk->set_sp(chunk->bottom());
2093 chunk->set_max_thawing_size(0);
2094 }
2095
2096 int ThawBase::remove_scalarized_frames(StackChunkFrameStream<ChunkFrames::CompiledOnly>& f, int &argsize) {
2097 intptr_t* top = f.sp();
2098
2099 while (f.cb()->as_nmethod()->needs_stack_repair()) {
2100 f.next(SmallRegisterMap::instance(), false /* stop */);
2101 }
2102 assert(!f.is_done(), "");
2103 assert(f.is_compiled(), "");
2104
2105 intptr_t* bottom = f.sp() + f.cb()->frame_size();
2106 argsize = f.stack_argsize();
2107 return bottom - top;
2108 }
2109
2110 template<bool check_stub>
2111 int ThawBase::remove_top_compiled_frame_from_chunk(stackChunkOop chunk, int &argsize) {
2112 bool empty = false;
2113 StackChunkFrameStream<ChunkFrames::CompiledOnly> f(chunk);
2114 DEBUG_ONLY(intptr_t* const chunk_sp = chunk->start_address() + chunk->sp();)
2115 assert(chunk_sp == f.sp(), "");
2116 assert(chunk_sp == f.unextended_sp(), "");
2117
2118 int frame_size = f.cb()->frame_size();
2119 argsize = f.stack_argsize();
2120
2121 assert(!f.is_stub() || check_stub, "");
2122 if (check_stub && f.is_stub()) {
2123 // If we don't thaw the top compiled frame too, after restoring the saved
2124 // registers back in Java, we would hit the return barrier to thaw one more
2125 // frame effectively overwriting the restored registers during that call.
2126 f.next(SmallRegisterMap::instance(), true /* stop */);
2127 assert(!f.is_done(), "");
2128
2129 f.get_cb();
2130 assert(f.is_compiled(), "");
2131 if (f.cb()->as_nmethod()->is_marked_for_deoptimization()) {
2132 // The caller of the runtime stub when the continuation is preempted is not at a
2133 // Java call instruction, and so cannot rely on nmethod patching for deopt.
2134 log_develop_trace(continuations)("Deoptimizing runtime stub caller");
2135 f.to_frame().deoptimize(nullptr); // the null thread simply avoids the assertion in deoptimize which we're not set up for
2136 }
2137
2138 if (f.cb()->as_nmethod()->needs_stack_repair()) {
2139 frame_size += remove_scalarized_frames(f, argsize);
2140 } else {
2141 frame_size += f.cb()->frame_size();
2142 argsize = f.stack_argsize();
2143 }
2144 } else if (f.cb()->as_nmethod()->needs_stack_repair()) {
2145 frame_size = remove_scalarized_frames(f, argsize);
2146 }
2147
2148 f.next(SmallRegisterMap::instance(), true /* stop */);
2149 empty = f.is_done();
2150 assert(!empty || argsize == chunk->argsize(), "");
2151
2152 if (empty) {
2153 clear_chunk(chunk);
2154 } else {
2155 chunk->set_sp(chunk->sp() + frame_size);
2156 chunk->set_max_thawing_size(chunk->max_thawing_size() - frame_size);
2157 // We set chunk->pc to the return pc into the next frame
2158 chunk->set_pc(f.pc());
2159 #ifdef ASSERT
2160 {
2161 intptr_t* retaddr_slot = (chunk_sp
2162 + frame_size
2163 - frame::sender_sp_ret_address_offset());
2164 assert(f.pc() == ContinuationHelper::return_address_at(retaddr_slot),
2165 "unexpected pc");
2166 }
2167 #endif
2168 }
2169 assert(empty == chunk->is_empty(), "");
2170 // returns the size required to store the frame on stack, and because it is a
2171 // compiled frame, it must include a copy of the arguments passed by the caller
2172 return frame_size + argsize + frame::metadata_words_at_top;
2173 }
2174
2175 void ThawBase::thaw_lockstack(stackChunkOop chunk) {
2176 int lockStackSize = chunk->lockstack_size();
2177 assert(lockStackSize > 0 && lockStackSize <= LockStack::CAPACITY, "");
2178
2179 oop tmp_lockstack[LockStack::CAPACITY];
2180 chunk->transfer_lockstack(tmp_lockstack, _barriers);
2181 _thread->lock_stack().move_from_address(tmp_lockstack, lockStackSize);
2182
2183 chunk->set_lockstack_size(0);
2184 chunk->set_has_lockstack(false);
2185 }
2186
2187 void ThawBase::copy_from_chunk(intptr_t* from, intptr_t* to, int size) {
2188 assert(to >= _top_stack_address, "overwrote past thawing space"
2189 " to: " INTPTR_FORMAT " top_address: " INTPTR_FORMAT, p2i(to), p2i(_top_stack_address));
2190 assert(to + size <= _cont.entrySP(), "overwrote past thawing space");
2191 _cont.tail()->copy_from_chunk_to_stack(from, to, size);
2192 CONT_JFR_ONLY(_jfr_info.record_size_copied(size);)
2193 }
2194
2195 void ThawBase::patch_return(intptr_t* sp, bool is_last) {
2196 log_develop_trace(continuations)("thaw_fast patching -- sp: " INTPTR_FORMAT, p2i(sp));
2197
2198 address pc = !is_last ? StubRoutines::cont_returnBarrier() : _cont.entryPC();
2199 ContinuationHelper::patch_return_address_at(
2200 sp - frame::sender_sp_ret_address_offset(),
2201 pc);
2202 }
2203
2204 template <typename ConfigT>
2205 template<bool check_stub>
2206 NOINLINE intptr_t* Thaw<ConfigT>::thaw_fast(stackChunkOop chunk) {
2207 assert(chunk == _cont.tail(), "");
2208 assert(!chunk->has_mixed_frames(), "");
2209 assert(!chunk->requires_barriers(), "");
2210 assert(!chunk->has_bitmap(), "");
2211 assert(!_thread->is_interp_only_mode(), "");
2212
2213 LogTarget(Trace, continuations) lt;
2214 if (lt.develop_is_enabled()) {
2215 LogStream ls(lt);
2216 ls.print_cr("thaw_fast");
2217 chunk->print_on(true, &ls);
2218 }
2219
2220 // Below this heuristic, we thaw the whole chunk, above it we thaw just one frame.
2221 static const int threshold = 500; // words
2222
2223 const int full_chunk_size = chunk->stack_size() - chunk->sp(); // this initial size could be reduced if it's a partial thaw
2224 int argsize, thaw_size;
2225
2226 intptr_t* const chunk_sp = chunk->start_address() + chunk->sp();
2227
2228 bool partial, empty;
2229 if (LIKELY(!TEST_THAW_ONE_CHUNK_FRAME && (full_chunk_size < threshold))) {
2230 prefetch_chunk_pd(chunk->start_address(), full_chunk_size); // prefetch anticipating memcpy starting at highest address
2231
2232 partial = false;
2233 argsize = chunk->argsize(); // must be called *before* clearing the chunk
2234 clear_chunk(chunk);
2235 thaw_size = full_chunk_size;
2236 empty = true;
2237 } else { // thaw a single frame
2238 partial = true;
2239 thaw_size = remove_top_compiled_frame_from_chunk<check_stub>(chunk, argsize);
2240 empty = chunk->is_empty();
2241 }
2242
2243 // Are we thawing the last frame(s) in the continuation
2244 const bool is_last = empty && chunk->parent() == nullptr;
2245 assert(!is_last || argsize == 0, "");
2246
2247 log_develop_trace(continuations)("thaw_fast partial: %d is_last: %d empty: %d size: %d argsize: %d entrySP: " PTR_FORMAT,
2248 partial, is_last, empty, thaw_size, argsize, p2i(_cont.entrySP()));
2249
2250 ReconstructedStack rs(_cont.entrySP(), thaw_size, argsize);
2251
2252 // also copy metadata words at frame bottom
2253 copy_from_chunk(chunk_sp - frame::metadata_words_at_bottom, rs.top(), rs.total_size());
2254
2255 // update the ContinuationEntry
2256 _cont.set_argsize(argsize);
2257 log_develop_trace(continuations)("setting entry argsize: %d", _cont.argsize());
2258 assert(rs.bottom_sp() == _cont.entry()->bottom_sender_sp(), "");
2259
2260 // install the return barrier if not last frame, or the entry's pc if last
2261 patch_return(rs.bottom_sp(), is_last);
2262
2263 // insert the back links from callee to caller frames
2264 patch_caller_links(rs.top(), rs.top() + rs.total_size());
2265
2266 assert(is_last == _cont.is_empty(), "");
2267 assert(_cont.chunk_invariant(), "");
2268
2269 #if CONT_JFR
2270 EventContinuationThawFast e;
2271 if (e.should_commit()) {
2272 e.set_id(cast_from_oop<u8>(chunk));
2273 e.set_size(thaw_size << LogBytesPerWord);
2274 e.set_full(!partial);
2275 e.commit();
2276 }
2277 #endif
2278
2279 #ifdef ASSERT
2280 set_anchor(_thread, rs.sp());
2281 log_frames(_thread);
2282 if (LoomDeoptAfterThaw) {
2283 do_deopt_after_thaw(_thread);
2284 }
2285 clear_anchor(_thread);
2286 #endif
2287
2288 return rs.sp();
2289 }
2290
2291 inline bool ThawBase::seen_by_gc() {
2292 return _barriers || _cont.tail()->is_gc_mode();
2293 }
2294
2295 static inline void relativize_chunk_concurrently(stackChunkOop chunk) {
2296 #if INCLUDE_ZGC || INCLUDE_SHENANDOAHGC
2297 if (UseZGC || UseShenandoahGC) {
2298 chunk->relativize_derived_pointers_concurrently();
2299 }
2300 #endif
2301 }
2302
2303 template <typename ConfigT>
2304 NOINLINE intptr_t* Thaw<ConfigT>::thaw_slow(stackChunkOop chunk, Continuation::thaw_kind kind) {
2305 Continuation::preempt_kind preempt_kind;
2306 bool retry_fast_path = false;
2307
2308 _preempted_case = chunk->preempted();
2309 if (_preempted_case) {
2310 ObjectWaiter* waiter = java_lang_VirtualThread::objectWaiter(_thread->vthread());
2311 if (waiter != nullptr) {
2312 // Mounted again after preemption. Resume the pending monitor operation,
2313 // which will be either a monitorenter or Object.wait() call.
2314 ObjectMonitor* mon = waiter->monitor();
2315 preempt_kind = waiter->is_wait() ? Continuation::freeze_on_wait : Continuation::freeze_on_monitorenter;
2316
2317 bool mon_acquired = mon->resume_operation(_thread, waiter, _cont);
2318 assert(!mon_acquired || mon->has_owner(_thread), "invariant");
2319 if (!mon_acquired) {
2320 // Failed to acquire monitor. Return to enterSpecial to unmount again.
2321 return push_cleanup_continuation();
2322 }
2323 chunk = _cont.tail(); // reload oop in case of safepoint in resume_operation (if posting JVMTI events).
2324 } else {
2325 // Preemption cancelled in moniterenter case. We actually acquired
2326 // the monitor after freezing all frames so nothing to do.
2327 preempt_kind = Continuation::freeze_on_monitorenter;
2328 }
2329 // Call this first to avoid racing with GC threads later when modifying the chunk flags.
2330 relativize_chunk_concurrently(chunk);
2331 chunk->set_preempted(false);
2332 retry_fast_path = true;
2333 } else {
2334 relativize_chunk_concurrently(chunk);
2335 }
2336
2337 // On first thaw after freeze restore oops to the lockstack if any.
2338 assert(chunk->lockstack_size() == 0 || kind == Continuation::thaw_top, "");
2339 if (kind == Continuation::thaw_top && chunk->lockstack_size() > 0) {
2340 thaw_lockstack(chunk);
2341 retry_fast_path = true;
2342 }
2343
2344 // Retry the fast path now that we possibly cleared the FLAG_HAS_LOCKSTACK
2345 // and FLAG_PREEMPTED flags from the stackChunk.
2346 if (retry_fast_path && can_thaw_fast(chunk)) {
2347 intptr_t* sp = thaw_fast<true>(chunk);
2348 if (_preempted_case) {
2349 return handle_preempted_continuation(sp, preempt_kind, true /* fast_case */);
2350 }
2351 return sp;
2352 }
2353
2354 LogTarget(Trace, continuations) lt;
2355 if (lt.develop_is_enabled()) {
2356 LogStream ls(lt);
2357 ls.print_cr("thaw slow return_barrier: %d " INTPTR_FORMAT, kind, p2i(chunk));
2358 chunk->print_on(true, &ls);
2359 }
2360
2361 #if CONT_JFR
2362 EventContinuationThawSlow e;
2363 if (e.should_commit()) {
2364 e.set_id(cast_from_oop<u8>(_cont.continuation()));
2365 e.commit();
2366 }
2367 #endif
2368
2369 DEBUG_ONLY(_frames = 0;)
2370 _align_size = 0;
2371 int num_frames = kind == Continuation::thaw_top ? 2 : 1;
2372
2373 _stream = StackChunkFrameStream<ChunkFrames::Mixed>(chunk);
2374 _top_unextended_sp_before_thaw = _stream.unextended_sp();
2375
2376 frame heap_frame = _stream.to_frame();
2377 if (lt.develop_is_enabled()) {
2378 LogStream ls(lt);
2379 ls.print_cr("top hframe before (thaw):");
2380 assert(heap_frame.is_heap_frame(), "should have created a relative frame");
2381 heap_frame.print_value_on(&ls);
2382 }
2383
2384 frame caller; // the thawed caller on the stack
2385 recurse_thaw(heap_frame, caller, num_frames, _preempted_case);
2386 finish_thaw(caller); // caller is now the topmost thawed frame
2387 _cont.write();
2388
2389 assert(_cont.chunk_invariant(), "");
2390
2391 JVMTI_ONLY(invalidate_jvmti_stack(_thread));
2392
2393 _thread->set_cont_fastpath(_fastpath);
2394
2395 intptr_t* sp = caller.sp();
2396
2397 if (_preempted_case) {
2398 return handle_preempted_continuation(sp, preempt_kind, false /* fast_case */);
2399 }
2400 return sp;
2401 }
2402
2403 void ThawBase::recurse_thaw(const frame& heap_frame, frame& caller, int num_frames, bool top_on_preempt_case) {
2404 log_develop_debug(continuations)("thaw num_frames: %d", num_frames);
2405 assert(!_cont.is_empty(), "no more frames");
2406 assert(num_frames > 0, "");
2407 assert(!heap_frame.is_empty(), "");
2408
2409 if (top_on_preempt_case && (heap_frame.is_native_frame() || heap_frame.is_runtime_frame())) {
2410 heap_frame.is_native_frame() ? recurse_thaw_native_frame(heap_frame, caller, 2) : recurse_thaw_stub_frame(heap_frame, caller, 2);
2411 } else if (!heap_frame.is_interpreted_frame()) {
2412 recurse_thaw_compiled_frame(heap_frame, caller, num_frames, false);
2413 } else {
2414 recurse_thaw_interpreted_frame(heap_frame, caller, num_frames);
2415 }
2416 }
2417
2418 template<typename FKind>
2419 bool ThawBase::recurse_thaw_java_frame(frame& caller, int num_frames) {
2420 assert(num_frames > 0, "");
2421
2422 DEBUG_ONLY(_frames++;)
2423
2424 int argsize = _stream.stack_argsize();
2425 CodeBlob* cb = _stream.cb();
2426
2427 _stream.next(SmallRegisterMap::instance());
2428 assert(_stream.to_frame().is_empty() == _stream.is_done(), "");
2429
2430 // We never leave a compiled caller of an interpreted frame as the top frame in the chunk
2431 // as it makes detecting that situation and adjusting unextended_sp tricky. We also always
2432 // thaw the caller of a frame that needs_stack_repair, as it would otherwise complicate things:
2433 // - Regardless of whether the frame was extended or not, we would need to copy the right arg
2434 // size if its greater than the one given by the normal method signature (non-scalarized).
2435 // - If the frame was indeed extended, leaving its caller as the top frame would complicate walking
2436 // the chunk (we need unextended_sp, but we only have sp).
2437 if (num_frames == 1 && !_stream.is_done() && ((FKind::interpreted && _stream.is_compiled()) || (FKind::compiled && cb->as_nmethod_or_null()->needs_stack_repair()))) {
2438 log_develop_trace(continuations)("thawing extra compiled frame to not leave a compiled interpreted-caller at top");
2439 num_frames++;
2440 }
2441
2442 if (num_frames == 1 || _stream.is_done()) { // end recursion
2443 finalize_thaw(caller, FKind::interpreted ? 0 : argsize);
2444 return true; // bottom
2445 } else { // recurse
2446 recurse_thaw(_stream.to_frame(), caller, num_frames - 1, false /* top_on_preempt_case */);
2447 return false;
2448 }
2449 }
2450
2451 void ThawBase::finalize_thaw(frame& entry, int argsize) {
2452 stackChunkOop chunk = _cont.tail();
2453
2454 if (!_stream.is_done()) {
2455 assert(_stream.sp() >= chunk->sp_address(), "");
2456 chunk->set_sp(chunk->to_offset(_stream.sp()));
2457 chunk->set_pc(_stream.pc());
2458 } else {
2459 chunk->set_sp(chunk->bottom());
2460 chunk->set_pc(nullptr);
2461 }
2462 assert(_stream.is_done() == chunk->is_empty(), "");
2463
2464 int total_thawed = pointer_delta_as_int(_stream.unextended_sp(), _top_unextended_sp_before_thaw);
2465 chunk->set_max_thawing_size(chunk->max_thawing_size() - total_thawed);
2466
2467 _cont.set_argsize(argsize);
2468 entry = new_entry_frame();
2469
2470 assert(entry.sp() == _cont.entrySP(), "");
2471 assert(Continuation::is_continuation_enterSpecial(entry), "");
2472 assert(_cont.is_entry_frame(entry), "");
2473 }
2474
2475 inline void ThawBase::before_thaw_java_frame(const frame& hf, const frame& caller, bool bottom, int num_frame) {
2476 LogTarget(Trace, continuations) lt;
2477 if (lt.develop_is_enabled()) {
2478 LogStream ls(lt);
2479 ls.print_cr("======== THAWING FRAME: %d", num_frame);
2480 assert(hf.is_heap_frame(), "should be");
2481 hf.print_value_on(&ls);
2482 }
2483 assert(bottom == _cont.is_entry_frame(caller), "bottom: %d is_entry_frame: %d", bottom, _cont.is_entry_frame(hf));
2484 }
2485
2486 inline void ThawBase::after_thaw_java_frame(const frame& f, bool bottom) {
2487 #ifdef ASSERT
2488 LogTarget(Trace, continuations) lt;
2489 if (lt.develop_is_enabled()) {
2490 LogStream ls(lt);
2491 ls.print_cr("thawed frame:");
2492 print_frame_layout(f, false, &ls); // f.print_on(&ls);
2493 }
2494 #endif
2495 }
2496
2497 inline void ThawBase::patch(frame& f, const frame& caller, bool bottom, bool augmented) {
2498 assert(!bottom || caller.fp() == _cont.entryFP(), "");
2499 if (bottom) {
2500 ContinuationHelper::Frame::patch_pc(caller, _cont.is_empty() ? caller.pc()
2501 : StubRoutines::cont_returnBarrier());
2502 } else if (caller.is_compiled_frame()){
2503 // caller might have been deoptimized during thaw but we've overwritten the return address when copying f from the heap.
2504 // If the caller is not deoptimized, pc is unchanged.
2505 ContinuationHelper::Frame::patch_pc(caller, caller.raw_pc(), augmented /*callee_augmented*/);
2506 }
2507
2508 patch_pd(f, caller);
2509
2510 if (f.is_interpreted_frame()) {
2511 ContinuationHelper::InterpretedFrame::patch_sender_sp(f, caller);
2512 }
2513
2514 assert(!bottom || !_cont.is_empty() || Continuation::is_continuation_entry_frame(f, nullptr), "");
2515 assert(!bottom || (_cont.is_empty() != Continuation::is_cont_barrier_frame(f)), "");
2516 }
2517
2518 void ThawBase::clear_bitmap_bits(address start, address end) {
2519 assert(is_aligned(start, wordSize), "should be aligned: " PTR_FORMAT, p2i(start));
2520 assert(is_aligned(end, VMRegImpl::stack_slot_size), "should be aligned: " PTR_FORMAT, p2i(end));
2521
2522 // we need to clear the bits that correspond to arguments as they reside in the caller frame
2523 // or they will keep objects that are otherwise unreachable alive.
2524
2525 // Align `end` if UseCompressedOops is not set to avoid UB when calculating the bit index, since
2526 // `end` could be at an odd number of stack slots from `start`, i.e might not be oop aligned.
2527 // If that's the case the bit range corresponding to the last stack slot should not have bits set
2528 // anyways and we assert that before returning.
2529 address effective_end = UseCompressedOops ? end : align_down(end, wordSize);
2530 log_develop_trace(continuations)("clearing bitmap for " INTPTR_FORMAT " - " INTPTR_FORMAT, p2i(start), p2i(effective_end));
2531 stackChunkOop chunk = _cont.tail();
2532 chunk->bitmap().clear_range(chunk->bit_index_for(start), chunk->bit_index_for(effective_end));
2533 assert(effective_end == end || !chunk->bitmap().at(chunk->bit_index_for(effective_end)), "bit should not be set");
2534 }
2535
2536 intptr_t* ThawBase::handle_preempted_continuation(intptr_t* sp, Continuation::preempt_kind preempt_kind, bool fast_case) {
2537 assert(preempt_kind == Continuation::freeze_on_wait || preempt_kind == Continuation::freeze_on_monitorenter, "");
2538 frame top(sp);
2539 assert(top.pc() == *(address*)(sp - frame::sender_sp_ret_address_offset()), "");
2540
2541 #if INCLUDE_JVMTI
2542 // Finish the VTMS transition.
2543 assert(_thread->is_in_VTMS_transition(), "must be");
2544 bool is_vthread = Continuation::continuation_scope(_cont.continuation()) == java_lang_VirtualThread::vthread_scope();
2545 if (is_vthread) {
2546 if (JvmtiVTMSTransitionDisabler::VTMS_notify_jvmti_events()) {
2547 jvmti_mount_end(_thread, _cont, top);
2548 } else {
2549 _thread->set_is_in_VTMS_transition(false);
2550 java_lang_Thread::set_is_in_VTMS_transition(_thread->vthread(), false);
2551 }
2552 }
2553 #endif
2554
2555 if (fast_case) {
2556 // If we thawed in the slow path the runtime stub/native wrapper frame already
2557 // has the correct fp (see ThawBase::new_stack_frame). On the fast path though,
2558 // we copied the fp patched during freeze, which will now have to be fixed.
2559 assert(top.is_runtime_frame() || top.is_native_frame(), "");
2560 int fsize = top.cb()->frame_size();
2561 patch_pd(top, sp + fsize);
2562 }
2563
2564 if (preempt_kind == Continuation::freeze_on_wait) {
2565 // Check now if we need to throw IE exception.
2566 if (_thread->pending_interrupted_exception()) {
2567 throw_interrupted_exception(_thread, top);
2568 _thread->set_pending_interrupted_exception(false);
2569 }
2570 } else if (top.is_runtime_frame()) {
2571 // The continuation might now run on a different platform thread than the previous time so
2572 // we need to adjust the current thread saved in the stub frame before restoring registers.
2573 JavaThread** thread_addr = frame::saved_thread_address(top);
2574 if (thread_addr != nullptr) *thread_addr = _thread;
2575 }
2576 return sp;
2577 }
2578
2579 void ThawBase::throw_interrupted_exception(JavaThread* current, frame& top) {
2580 ContinuationWrapper::SafepointOp so(current, _cont);
2581 // Since we might safepoint set the anchor so that the stack can be walked.
2582 set_anchor(current, top.sp());
2583 JRT_BLOCK
2584 THROW(vmSymbols::java_lang_InterruptedException());
2585 JRT_BLOCK_END
2586 clear_anchor(current);
2587 }
2588
2589 NOINLINE void ThawBase::recurse_thaw_interpreted_frame(const frame& hf, frame& caller, int num_frames) {
2590 assert(hf.is_interpreted_frame(), "");
2591
2592 if (UNLIKELY(seen_by_gc())) {
2593 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance());
2594 }
2595
2596 const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::InterpretedFrame>(caller, num_frames);
2597
2598 DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2599
2600 _align_size += frame::align_wiggle; // possible added alignment for internal interpreted frame alignment om AArch64
2601
2602 frame f = new_stack_frame<ContinuationHelper::InterpretedFrame>(hf, caller, is_bottom_frame);
2603
2604 intptr_t* const stack_frame_top = f.sp() + frame::metadata_words_at_top;
2605 intptr_t* const stack_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(f);
2606 intptr_t* const heap_frame_top = hf.unextended_sp() + frame::metadata_words_at_top;
2607 intptr_t* const heap_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(hf);
2608
2609 assert(hf.is_heap_frame(), "should be");
2610 assert(!f.is_heap_frame(), "should not be");
2611
2612 const int fsize = pointer_delta_as_int(heap_frame_bottom, heap_frame_top);
2613 assert((stack_frame_bottom == stack_frame_top + fsize), "");
2614
2615 // Some architectures (like AArch64/PPC64/RISC-V) add padding between the locals and the fixed_frame to keep the fp 16-byte-aligned.
2616 // On those architectures we freeze the padding in order to keep the same fp-relative offsets in the fixed_frame.
2617 copy_from_chunk(heap_frame_top, stack_frame_top, fsize);
2618
2619 // Make sure the relativized locals is already set.
2620 assert(f.interpreter_frame_local_at(0) == stack_frame_bottom - 1, "invalid frame bottom");
2621
2622 derelativize_interpreted_frame_metadata(hf, f);
2623 patch(f, caller, is_bottom_frame);
2624
2625 assert(f.is_interpreted_frame_valid(_cont.thread()), "invalid thawed frame");
2626 assert(stack_frame_bottom <= ContinuationHelper::Frame::frame_top(caller), "");
2627
2628 CONT_JFR_ONLY(_jfr_info.record_interpreted_frame();)
2629
2630 maybe_set_fastpath(f.sp());
2631
2632 Method* m = hf.interpreter_frame_method();
2633 assert(!m->is_native() || !is_bottom_frame, "should be top frame of thaw_top case; missing caller frame");
2634 const int locals = m->max_locals();
2635
2636 if (!is_bottom_frame) {
2637 // can only fix caller once this frame is thawed (due to callee saved regs)
2638 _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance());
2639 } else if (_cont.tail()->has_bitmap() && locals > 0) {
2640 assert(hf.is_heap_frame(), "should be");
2641 address start = (address)(heap_frame_bottom - locals);
2642 address end = (address)heap_frame_bottom;
2643 clear_bitmap_bits(start, end);
2644 }
2645
2646 DEBUG_ONLY(after_thaw_java_frame(f, is_bottom_frame);)
2647 caller = f;
2648 }
2649
2650 void ThawBase::recurse_thaw_compiled_frame(const frame& hf, frame& caller, int num_frames, bool stub_caller) {
2651 assert(hf.is_compiled_frame(), "");
2652 assert(_preempted_case || !stub_caller, "stub caller not at preemption");
2653
2654 if (!stub_caller && UNLIKELY(seen_by_gc())) { // recurse_thaw_stub_frame already invoked our barriers with a full regmap
2655 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance());
2656 }
2657
2658 const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::CompiledFrame>(caller, num_frames);
2659
2660 DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2661
2662 assert(caller.sp() == caller.unextended_sp(), "");
2663
2664 if ((!is_bottom_frame && caller.is_interpreted_frame()) || (is_bottom_frame && Interpreter::contains(_cont.tail()->pc()))) {
2665 _align_size += frame::align_wiggle; // we add one whether or not we've aligned because we add it in recurse_freeze_compiled_frame
2666 }
2667
2668 int fsize = 0;
2669 int added_argsize = 0;
2670 bool augmented = hf.was_augmented_on_entry(fsize);
2671 if (!augmented) {
2672 added_argsize = (is_bottom_frame || caller.is_interpreted_frame()) ? hf.compiled_frame_stack_argsize() : 0;
2673 fsize += added_argsize;
2674 }
2675 assert(!is_bottom_frame || !augmented, "");
2676
2677
2678 // new_stack_frame must construct the resulting frame using hf.pc() rather than hf.raw_pc() because the frame is not
2679 // yet laid out in the stack, and so the original_pc is not stored in it.
2680 // As a result, f.is_deoptimized_frame() is always false and we must test hf to know if the frame is deoptimized.
2681 frame f = new_stack_frame<ContinuationHelper::CompiledFrame>(hf, caller, is_bottom_frame, augmented ? fsize - hf.cb()->frame_size() : 0);
2682 assert(f.cb()->frame_size() == (int)(caller.sp() - f.sp()), "");
2683
2684 intptr_t* const stack_frame_top = f.sp();
2685 intptr_t* const heap_frame_top = hf.unextended_sp();
2686 intptr_t* from = heap_frame_top - frame::metadata_words_at_bottom;
2687 intptr_t* to = stack_frame_top - frame::metadata_words_at_bottom;
2688 // copy metadata, except the metadata at the top of the (unextended) entry frame
2689 int sz = fsize + frame::metadata_words_at_bottom + (is_bottom_frame && added_argsize == 0 ? 0 : frame::metadata_words_at_top);
2690
2691 // If we're the bottom-most thawed frame, we're writing to within one word from entrySP
2692 // (we might have one padding word for alignment)
2693 assert(!is_bottom_frame || (_cont.entrySP() - 1 <= to + sz && to + sz <= _cont.entrySP()), "");
2694 assert(!is_bottom_frame || hf.compiled_frame_stack_argsize() != 0 || (to + sz && to + sz == _cont.entrySP()), "");
2695
2696 copy_from_chunk(from, to, sz); // copying good oops because we invoked barriers above
2697
2698 patch(f, caller, is_bottom_frame, augmented);
2699
2700 // f.is_deoptimized_frame() is always false and we must test hf.is_deoptimized_frame() (see comment above)
2701 assert(!f.is_deoptimized_frame(), "");
2702 if (hf.is_deoptimized_frame()) {
2703 maybe_set_fastpath(f.sp());
2704 } else if (_thread->is_interp_only_mode()
2705 || (stub_caller && f.cb()->as_nmethod()->is_marked_for_deoptimization())) {
2706 // The caller of the safepoint stub when the continuation is preempted is not at a call instruction, and so
2707 // cannot rely on nmethod patching for deopt.
2708 assert(_thread->is_interp_only_mode() || stub_caller, "expected a stub-caller");
2709
2710 log_develop_trace(continuations)("Deoptimizing thawed frame");
2711 DEBUG_ONLY(ContinuationHelper::Frame::patch_pc(f, nullptr));
2712
2713 f.deoptimize(nullptr); // the null thread simply avoids the assertion in deoptimize which we're not set up for
2714 assert(f.is_deoptimized_frame(), "");
2715 assert(ContinuationHelper::Frame::is_deopt_return(f.raw_pc(), f), "");
2716 maybe_set_fastpath(f.sp());
2717 }
2718
2719 if (!is_bottom_frame) {
2720 // can only fix caller once this frame is thawed (due to callee saved regs); this happens on the stack
2721 _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance());
2722 } else if (_cont.tail()->has_bitmap() && added_argsize > 0) {
2723 address start = (address)(heap_frame_top + ContinuationHelper::CompiledFrame::size(hf) + frame::metadata_words_at_top);
2724 int stack_args_slots = f.cb()->as_nmethod()->num_stack_arg_slots(false /* rounded */);
2725 int argsize_in_bytes = stack_args_slots * VMRegImpl::stack_slot_size;
2726 clear_bitmap_bits(start, start + argsize_in_bytes);
2727 }
2728
2729 DEBUG_ONLY(after_thaw_java_frame(f, is_bottom_frame);)
2730 caller = f;
2731 }
2732
2733 void ThawBase::recurse_thaw_stub_frame(const frame& hf, frame& caller, int num_frames) {
2734 DEBUG_ONLY(_frames++;)
2735
2736 if (UNLIKELY(seen_by_gc())) {
2737 // Process the stub's caller here since we might need the full map.
2738 RegisterMap map(nullptr,
2739 RegisterMap::UpdateMap::include,
2740 RegisterMap::ProcessFrames::skip,
2741 RegisterMap::WalkContinuation::skip);
2742 map.set_include_argument_oops(false);
2743 _stream.next(&map);
2744 assert(!_stream.is_done(), "");
2745 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, &map);
2746 } else {
2747 _stream.next(SmallRegisterMap::instance());
2748 assert(!_stream.is_done(), "");
2749 }
2750
2751 recurse_thaw_compiled_frame(_stream.to_frame(), caller, num_frames, true);
2752
2753 assert(caller.is_compiled_frame(), "");
2754 assert(caller.sp() == caller.unextended_sp(), "");
2755
2756 DEBUG_ONLY(before_thaw_java_frame(hf, caller, false /*is_bottom_frame*/, num_frames);)
2757
2758 frame f = new_stack_frame<ContinuationHelper::StubFrame>(hf, caller, false);
2759 intptr_t* stack_frame_top = f.sp();
2760 intptr_t* heap_frame_top = hf.sp();
2761 int fsize = ContinuationHelper::StubFrame::size(hf);
2762
2763 copy_from_chunk(heap_frame_top - frame::metadata_words, stack_frame_top - frame::metadata_words,
2764 fsize + frame::metadata_words);
2765
2766 patch(f, caller, false /*is_bottom_frame*/);
2767
2768 // can only fix caller once this frame is thawed (due to callee saved regs)
2769 RegisterMap map(nullptr,
2770 RegisterMap::UpdateMap::include,
2771 RegisterMap::ProcessFrames::skip,
2772 RegisterMap::WalkContinuation::skip);
2773 map.set_include_argument_oops(false);
2774 f.oop_map()->update_register_map(&f, &map);
2775 ContinuationHelper::update_register_map_with_callee(caller, &map);
2776 _cont.tail()->fix_thawed_frame(caller, &map);
2777
2778 DEBUG_ONLY(after_thaw_java_frame(f, false /*is_bottom_frame*/);)
2779 caller = f;
2780 }
2781
2782 void ThawBase::recurse_thaw_native_frame(const frame& hf, frame& caller, int num_frames) {
2783 assert(hf.is_native_frame(), "");
2784 assert(_preempted_case && hf.cb()->as_nmethod()->method()->is_object_wait0(), "");
2785
2786 if (UNLIKELY(seen_by_gc())) { // recurse_thaw_stub_frame already invoked our barriers with a full regmap
2787 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance());
2788 }
2789
2790 const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::NativeFrame>(caller, num_frames);
2791 assert(!is_bottom_frame, "");
2792
2793 DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2794
2795 assert(caller.sp() == caller.unextended_sp(), "");
2796
2797 if (caller.is_interpreted_frame()) {
2798 _align_size += frame::align_wiggle; // we add one whether or not we've aligned because we add it in recurse_freeze_native_frame
2799 }
2800
2801 // new_stack_frame must construct the resulting frame using hf.pc() rather than hf.raw_pc() because the frame is not
2802 // yet laid out in the stack, and so the original_pc is not stored in it.
2803 // As a result, f.is_deoptimized_frame() is always false and we must test hf to know if the frame is deoptimized.
2804 frame f = new_stack_frame<ContinuationHelper::NativeFrame>(hf, caller, false /* bottom */);
2805 intptr_t* const stack_frame_top = f.sp();
2806 intptr_t* const heap_frame_top = hf.unextended_sp();
2807
2808 int fsize = ContinuationHelper::NativeFrame::size(hf);
2809 assert(fsize <= (int)(caller.unextended_sp() - f.unextended_sp()), "");
2810
2811 intptr_t* from = heap_frame_top - frame::metadata_words_at_bottom;
2812 intptr_t* to = stack_frame_top - frame::metadata_words_at_bottom;
2813 int sz = fsize + frame::metadata_words_at_bottom;
2814
2815 copy_from_chunk(from, to, sz); // copying good oops because we invoked barriers above
2816
2817 patch(f, caller, false /* bottom */);
2818
2819 // f.is_deoptimized_frame() is always false and we must test hf.is_deoptimized_frame() (see comment above)
2820 assert(!f.is_deoptimized_frame(), "");
2821 assert(!hf.is_deoptimized_frame(), "");
2822 assert(!f.cb()->as_nmethod()->is_marked_for_deoptimization(), "");
2823
2824 // can only fix caller once this frame is thawed (due to callee saved regs); this happens on the stack
2825 _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance());
2826
2827 DEBUG_ONLY(after_thaw_java_frame(f, false /* bottom */);)
2828 caller = f;
2829 }
2830
2831 void ThawBase::finish_thaw(frame& f) {
2832 stackChunkOop chunk = _cont.tail();
2833
2834 if (chunk->is_empty()) {
2835 // Only remove chunk from list if it can't be reused for another freeze
2836 if (seen_by_gc()) {
2837 _cont.set_tail(chunk->parent());
2838 } else {
2839 chunk->set_has_mixed_frames(false);
2840 }
2841 chunk->set_max_thawing_size(0);
2842 } else {
2843 chunk->set_max_thawing_size(chunk->max_thawing_size() - _align_size);
2844 }
2845 assert(chunk->is_empty() == (chunk->max_thawing_size() == 0), "");
2846
2847 if (!is_aligned(f.sp(), frame::frame_alignment)) {
2848 assert(f.is_interpreted_frame(), "");
2849 f.set_sp(align_down(f.sp(), frame::frame_alignment));
2850 }
2851 push_return_frame(f);
2852 chunk->fix_thawed_frame(f, SmallRegisterMap::instance()); // can only fix caller after push_return_frame (due to callee saved regs)
2853
2854 assert(_cont.is_empty() == _cont.last_frame().is_empty(), "");
2855
2856 log_develop_trace(continuations)("thawed %d frames", _frames);
2857
2858 LogTarget(Trace, continuations) lt;
2859 if (lt.develop_is_enabled()) {
2860 LogStream ls(lt);
2861 ls.print_cr("top hframe after (thaw):");
2862 _cont.last_frame().print_value_on(&ls);
2863 }
2864 }
2865
2866 void ThawBase::push_return_frame(frame& f) { // see generate_cont_thaw
2867 assert(!f.is_compiled_frame() || f.is_deoptimized_frame() == f.cb()->as_nmethod()->is_deopt_pc(f.raw_pc()), "");
2868 assert(!f.is_compiled_frame() || f.is_deoptimized_frame() == (f.pc() != f.raw_pc()), "");
2869
2870 LogTarget(Trace, continuations) lt;
2871 if (lt.develop_is_enabled()) {
2872 LogStream ls(lt);
2873 ls.print_cr("push_return_frame");
2874 f.print_value_on(&ls);
2875 }
2876
2877 assert(f.sp() - frame::metadata_words_at_bottom >= _top_stack_address, "overwrote past thawing space"
2878 " to: " INTPTR_FORMAT " top_address: " INTPTR_FORMAT, p2i(f.sp() - frame::metadata_words), p2i(_top_stack_address));
2879 ContinuationHelper::Frame::patch_pc(f, f.raw_pc()); // in case we want to deopt the frame in a full transition, this is checked.
2880 ContinuationHelper::push_pd(f);
2881
2882 assert(ContinuationHelper::Frame::assert_frame_laid_out(f), "");
2883 }
2884
2885 // returns new top sp
2886 // called after preparations (stack overflow check and making room)
2887 template<typename ConfigT>
2888 static inline intptr_t* thaw_internal(JavaThread* thread, const Continuation::thaw_kind kind) {
2889 assert(thread == JavaThread::current(), "Must be current thread");
2890
2891 CONT_JFR_ONLY(EventContinuationThaw event;)
2892
2893 log_develop_trace(continuations)("~~~~ thaw kind: %d sp: " INTPTR_FORMAT, kind, p2i(thread->last_continuation()->entry_sp()));
2894
2895 ContinuationEntry* entry = thread->last_continuation();
2896 assert(entry != nullptr, "");
2897 oop oopCont = entry->cont_oop(thread);
2898
2899 assert(!jdk_internal_vm_Continuation::done(oopCont), "");
2900 assert(oopCont == get_continuation(thread), "");
2901 verify_continuation(oopCont);
2902
2903 assert(entry->is_virtual_thread() == (entry->scope(thread) == java_lang_VirtualThread::vthread_scope()), "");
2904
2905 ContinuationWrapper cont(thread, oopCont);
2906 log_develop_debug(continuations)("THAW #" INTPTR_FORMAT " " INTPTR_FORMAT, cont.hash(), p2i((oopDesc*)oopCont));
2907
2908 #ifdef ASSERT
2909 set_anchor_to_entry(thread, cont.entry());
2910 log_frames(thread);
2911 clear_anchor(thread);
2912 #endif
2913
2914 DEBUG_ONLY(bool preempted = cont.tail()->preempted();)
2915 Thaw<ConfigT> thw(thread, cont);
2916 intptr_t* const sp = thw.thaw(kind);
2917 assert(is_aligned(sp, frame::frame_alignment), "");
2918 DEBUG_ONLY(log_frames_after_thaw(thread, cont, sp, preempted);)
2919
2920 CONT_JFR_ONLY(thw.jfr_info().post_jfr_event(&event, cont.continuation(), thread);)
2921
2922 verify_continuation(cont.continuation());
2923 log_develop_debug(continuations)("=== End of thaw #" INTPTR_FORMAT, cont.hash());
2924
2925 return sp;
2926 }
2927
2928 #ifdef ASSERT
2929 static void do_deopt_after_thaw(JavaThread* thread) {
2930 int i = 0;
2931 StackFrameStream fst(thread, true, false);
2932 fst.register_map()->set_include_argument_oops(false);
2933 ContinuationHelper::update_register_map_with_callee(*fst.current(), fst.register_map());
2934 for (; !fst.is_done(); fst.next()) {
2935 if (fst.current()->cb()->is_nmethod()) {
2936 nmethod* nm = fst.current()->cb()->as_nmethod();
2937 if (!nm->method()->is_continuation_native_intrinsic()) {
2938 nm->make_deoptimized();
2939 }
2940 }
2941 }
2942 }
2943
2944 class ThawVerifyOopsClosure: public OopClosure {
2945 intptr_t* _p;
2946 outputStream* _st;
2947 bool is_good_oop(oop o) {
2948 return dbg_is_safe(o, -1) && dbg_is_safe(o->klass(), -1) && oopDesc::is_oop(o) && o->klass()->is_klass();
2949 }
2950 public:
2951 ThawVerifyOopsClosure(outputStream* st) : _p(nullptr), _st(st) {}
2952 intptr_t* p() { return _p; }
2953 void reset() { _p = nullptr; }
2954
2955 virtual void do_oop(oop* p) {
2956 oop o = *p;
2957 if (o == nullptr || is_good_oop(o)) {
2958 return;
2959 }
2960 _p = (intptr_t*)p;
2961 _st->print_cr("*** non-oop " PTR_FORMAT " found at " PTR_FORMAT, p2i(*p), p2i(p));
2962 }
2963 virtual void do_oop(narrowOop* p) {
2964 oop o = RawAccess<>::oop_load(p);
2965 if (o == nullptr || is_good_oop(o)) {
2966 return;
2967 }
2968 _p = (intptr_t*)p;
2969 _st->print_cr("*** (narrow) non-oop %x found at " PTR_FORMAT, (int)(*p), p2i(p));
2970 }
2971 };
2972
2973 static bool do_verify_after_thaw(JavaThread* thread, stackChunkOop chunk, outputStream* st) {
2974 assert(thread->has_last_Java_frame(), "");
2975
2976 ResourceMark rm;
2977 ThawVerifyOopsClosure cl(st);
2978 NMethodToOopClosure cf(&cl, false);
2979
2980 StackFrameStream fst(thread, true, false);
2981 fst.register_map()->set_include_argument_oops(false);
2982 ContinuationHelper::update_register_map_with_callee(*fst.current(), fst.register_map());
2983 for (; !fst.is_done() && !Continuation::is_continuation_enterSpecial(*fst.current()); fst.next()) {
2984 if (fst.current()->cb()->is_nmethod() && fst.current()->cb()->as_nmethod()->is_marked_for_deoptimization()) {
2985 st->print_cr(">>> do_verify_after_thaw deopt");
2986 fst.current()->deoptimize(nullptr);
2987 fst.current()->print_on(st);
2988 }
2989
2990 fst.current()->oops_do(&cl, &cf, fst.register_map());
2991 if (cl.p() != nullptr) {
2992 frame fr = *fst.current();
2993 st->print_cr("Failed for frame barriers: %d",chunk->requires_barriers());
2994 fr.print_on(st);
2995 if (!fr.is_interpreted_frame()) {
2996 st->print_cr("size: %d argsize: %d",
2997 ContinuationHelper::NonInterpretedUnknownFrame::size(fr),
2998 ContinuationHelper::NonInterpretedUnknownFrame::stack_argsize(fr));
2999 }
3000 VMReg reg = fst.register_map()->find_register_spilled_here(cl.p(), fst.current()->sp());
3001 if (reg != nullptr) {
3002 st->print_cr("Reg %s %d", reg->name(), reg->is_stack() ? (int)reg->reg2stack() : -99);
3003 }
3004 cl.reset();
3005 DEBUG_ONLY(thread->print_frame_layout();)
3006 if (chunk != nullptr) {
3007 chunk->print_on(true, st);
3008 }
3009 return false;
3010 }
3011 }
3012 return true;
3013 }
3014
3015 static void log_frames(JavaThread* thread) {
3016 const static int show_entry_callers = 3;
3017 LogTarget(Trace, continuations) lt;
3018 if (!lt.develop_is_enabled()) {
3019 return;
3020 }
3021 LogStream ls(lt);
3022
3023 ls.print_cr("------- frames --------- for thread " INTPTR_FORMAT, p2i(thread));
3024 if (!thread->has_last_Java_frame()) {
3025 ls.print_cr("NO ANCHOR!");
3026 }
3027
3028 RegisterMap map(thread,
3029 RegisterMap::UpdateMap::include,
3030 RegisterMap::ProcessFrames::include,
3031 RegisterMap::WalkContinuation::skip);
3032 map.set_include_argument_oops(false);
3033
3034 if (false) {
3035 for (frame f = thread->last_frame(); !f.is_entry_frame(); f = f.sender(&map)) {
3036 f.print_on(&ls);
3037 }
3038 } else {
3039 map.set_skip_missing(true);
3040 ResetNoHandleMark rnhm;
3041 ResourceMark rm;
3042 HandleMark hm(Thread::current());
3043 FrameValues values;
3044
3045 int i = 0;
3046 int post_entry = -1;
3047 for (frame f = thread->last_frame(); !f.is_first_frame(); f = f.sender(&map), i++) {
3048 f.describe(values, i, &map, i == 0);
3049 if (post_entry >= 0 || Continuation::is_continuation_enterSpecial(f))
3050 post_entry++;
3051 if (post_entry >= show_entry_callers)
3052 break;
3053 }
3054 values.print_on(thread, &ls);
3055 }
3056
3057 ls.print_cr("======= end frames =========");
3058 }
3059
3060 static void log_frames_after_thaw(JavaThread* thread, ContinuationWrapper& cont, intptr_t* sp, bool preempted) {
3061 intptr_t* sp0 = sp;
3062 address pc0 = *(address*)(sp - frame::sender_sp_ret_address_offset());
3063
3064 if (preempted && sp0 == cont.entrySP()) {
3065 // Still preempted (monitor not acquired) so no frames were thawed.
3066 assert(cont.tail()->preempted(), "");
3067 set_anchor(thread, cont.entrySP(), cont.entryPC());
3068 } else {
3069 set_anchor(thread, sp0);
3070 }
3071
3072 log_frames(thread);
3073 if (LoomVerifyAfterThaw) {
3074 assert(do_verify_after_thaw(thread, cont.tail(), tty), "");
3075 }
3076 assert(ContinuationEntry::assert_entry_frame_laid_out(thread), "");
3077 clear_anchor(thread);
3078
3079 LogTarget(Trace, continuations) lt;
3080 if (lt.develop_is_enabled()) {
3081 LogStream ls(lt);
3082 ls.print_cr("Jumping to frame (thaw):");
3083 frame(sp).print_value_on(&ls);
3084 }
3085 }
3086 #endif // ASSERT
3087
3088 #include CPU_HEADER_INLINE(continuationFreezeThaw)
3089
3090 #ifdef ASSERT
3091 static void print_frame_layout(const frame& f, bool callee_complete, outputStream* st) {
3092 ResourceMark rm;
3093 FrameValues values;
3094 assert(f.get_cb() != nullptr, "");
3095 RegisterMap map(f.is_heap_frame() ?
3096 nullptr :
3097 JavaThread::current(),
3098 RegisterMap::UpdateMap::include,
3099 RegisterMap::ProcessFrames::skip,
3100 RegisterMap::WalkContinuation::skip);
3101 map.set_include_argument_oops(false);
3102 map.set_skip_missing(true);
3103 if (callee_complete) {
3104 frame::update_map_with_saved_link(&map, ContinuationHelper::Frame::callee_link_address(f));
3105 }
3106 const_cast<frame&>(f).describe(values, 0, &map, true);
3107 values.print_on(static_cast<JavaThread*>(nullptr), st);
3108 }
3109 #endif
3110
3111 static address thaw_entry = nullptr;
3112 static address freeze_entry = nullptr;
3113 static address freeze_preempt_entry = nullptr;
3114
3115 address Continuation::thaw_entry() {
3116 return ::thaw_entry;
3117 }
3118
3119 address Continuation::freeze_entry() {
3120 return ::freeze_entry;
3121 }
3122
3123 address Continuation::freeze_preempt_entry() {
3124 return ::freeze_preempt_entry;
3125 }
3126
3127 class ConfigResolve {
3128 public:
3129 static void resolve() { resolve_compressed(); }
3130
3131 static void resolve_compressed() {
3132 UseCompressedOops ? resolve_gc<true>()
3133 : resolve_gc<false>();
3134 }
3135
3136 private:
3137 template <bool use_compressed>
3138 static void resolve_gc() {
3139 BarrierSet* bs = BarrierSet::barrier_set();
3140 assert(bs != nullptr, "freeze/thaw invoked before BarrierSet is set");
3141 switch (bs->kind()) {
3142 #define BARRIER_SET_RESOLVE_BARRIER_CLOSURE(bs_name) \
3143 case BarrierSet::bs_name: { \
3144 resolve<use_compressed, typename BarrierSet::GetType<BarrierSet::bs_name>::type>(); \
3145 } \
3146 break;
3147 FOR_EACH_CONCRETE_BARRIER_SET_DO(BARRIER_SET_RESOLVE_BARRIER_CLOSURE)
3148 #undef BARRIER_SET_RESOLVE_BARRIER_CLOSURE
3149
3150 default:
3151 fatal("BarrierSet resolving not implemented");
3152 };
3153 }
3154
3155 template <bool use_compressed, typename BarrierSetT>
3156 static void resolve() {
3157 typedef Config<use_compressed ? oop_kind::NARROW : oop_kind::WIDE, BarrierSetT> SelectedConfigT;
3158
3159 freeze_entry = (address)freeze<SelectedConfigT>;
3160 freeze_preempt_entry = (address)SelectedConfigT::freeze_preempt;
3161
3162 // If we wanted, we could templatize by kind and have three different thaw entries
3163 thaw_entry = (address)thaw<SelectedConfigT>;
3164 }
3165 };
3166
3167 void Continuation::init() {
3168 ConfigResolve::resolve();
3169 }