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 void adjust_interpreted_frame_unextended_sp(frame& f);
464 static inline void prepare_freeze_interpreted_top_frame(frame& f);
465 static inline void relativize_interpreted_frame_metadata(const frame& f, const frame& hf);
466
467 protected:
468 void freeze_fast_copy(stackChunkOop chunk, int chunk_start_sp CONT_JFR_ONLY(COMMA bool chunk_is_allocated));
469 bool freeze_fast_new_chunk(stackChunkOop chunk);
470 };
471
472 template <typename ConfigT>
473 class Freeze : public FreezeBase {
474 private:
475 stackChunkOop allocate_chunk(size_t stack_size, int argsize_md);
476
477 public:
478 inline Freeze(JavaThread* thread, ContinuationWrapper& cont, intptr_t* frame_sp, bool preempt)
479 : FreezeBase(thread, cont, frame_sp, preempt) {}
480
481 freeze_result try_freeze_fast();
482
483 protected:
484 virtual stackChunkOop allocate_chunk_slow(size_t stack_size, int argsize_md) override { return allocate_chunk(stack_size, argsize_md); }
485 };
486
487 FreezeBase::FreezeBase(JavaThread* thread, ContinuationWrapper& cont, intptr_t* frame_sp, bool preempt) :
488 _thread(thread), _cont(cont), _barriers(false), _preempt(preempt), _last_frame(false /* no initialization */) {
489 DEBUG_ONLY(_jvmti_event_collector = nullptr;)
490
491 assert(_thread != nullptr, "");
492 assert(_thread->last_continuation()->entry_sp() == _cont.entrySP(), "");
493
494 DEBUG_ONLY(_cont.entry()->verify_cookie();)
495
496 assert(!Interpreter::contains(_cont.entryPC()), "");
497
498 _bottom_address = _cont.entrySP() - _cont.entry_frame_extension();
499 #ifdef _LP64
500 if (((intptr_t)_bottom_address & 0xf) != 0) {
501 _bottom_address--;
502 }
503 assert(is_aligned(_bottom_address, frame::frame_alignment), "");
504 #endif
505
506 log_develop_trace(continuations)("bottom_address: " INTPTR_FORMAT " entrySP: " INTPTR_FORMAT " argsize: " PTR_FORMAT,
507 p2i(_bottom_address), p2i(_cont.entrySP()), (_cont.entrySP() - _bottom_address) << LogBytesPerWord);
508 assert(_bottom_address != nullptr, "");
509 assert(_bottom_address <= _cont.entrySP(), "");
510 DEBUG_ONLY(_last_write = nullptr;)
511
512 assert(_cont.chunk_invariant(), "");
513 assert(!Interpreter::contains(_cont.entryPC()), "");
514 #if !defined(PPC64) || defined(ZERO)
515 static const int doYield_stub_frame_size = frame::metadata_words;
516 #else
517 static const int doYield_stub_frame_size = frame::native_abi_reg_args_size >> LogBytesPerWord;
518 #endif
519 // With preemption doYield() might not have been resolved yet
520 assert(_preempt || SharedRuntime::cont_doYield_stub()->frame_size() == doYield_stub_frame_size, "");
521
522 if (preempt) {
523 _last_frame = _thread->last_frame();
524 }
525
526 // properties of the continuation on the stack; all sizes are in words
527 _cont_stack_top = frame_sp + (!preempt ? doYield_stub_frame_size : 0); // we don't freeze the doYield stub frame
528 _cont_stack_bottom = _cont.entrySP() + (_cont.argsize() == 0 ? frame::metadata_words_at_top : 0)
529 - ContinuationHelper::frame_align_words(_cont.argsize()); // see alignment in thaw
530
531 log_develop_trace(continuations)("freeze size: %d argsize: %d top: " INTPTR_FORMAT " bottom: " INTPTR_FORMAT,
532 cont_size(), _cont.argsize(), p2i(_cont_stack_top), p2i(_cont_stack_bottom));
533 assert(cont_size() > 0, "");
534
535 if (LockingMode != LM_LIGHTWEIGHT) {
536 _monitors_in_lockstack = 0;
537 } else {
538 _monitors_in_lockstack = _thread->lock_stack().monitor_count();
539 }
540 }
541
542 void FreezeBase::init_rest() { // we want to postpone some initialization after chunk handling
543 _freeze_size = 0;
544 _total_align_size = 0;
545 NOT_PRODUCT(_frames = 0;)
546 }
547
548 void FreezeBase::freeze_lockstack(stackChunkOop chunk) {
549 assert(chunk->sp_address() - chunk->start_address() >= _monitors_in_lockstack, "no room for lockstack");
550
551 _thread->lock_stack().move_to_address((oop*)chunk->start_address());
552 chunk->set_lockstack_size(checked_cast<uint8_t>(_monitors_in_lockstack));
553 chunk->set_has_lockstack(true);
554 }
555
556 void FreezeBase::copy_to_chunk(intptr_t* from, intptr_t* to, int size) {
557 stackChunkOop chunk = _cont.tail();
558 chunk->copy_from_stack_to_chunk(from, to, size);
559 CONT_JFR_ONLY(_jfr_info.record_size_copied(size);)
560
561 #ifdef ASSERT
562 if (_last_write != nullptr) {
563 assert(_last_write == to + size, "Missed a spot: _last_write: " INTPTR_FORMAT " to+size: " INTPTR_FORMAT
564 " stack_size: %d _last_write offset: " PTR_FORMAT " to+size: " PTR_FORMAT, p2i(_last_write), p2i(to+size),
565 chunk->stack_size(), _last_write-chunk->start_address(), to+size-chunk->start_address());
566 _last_write = to;
567 }
568 #endif
569 }
570
571 static void assert_frames_in_continuation_are_safe(JavaThread* thread) {
572 #ifdef ASSERT
573 StackWatermark* watermark = StackWatermarkSet::get(thread, StackWatermarkKind::gc);
574 if (watermark == nullptr) {
575 return;
576 }
577 ContinuationEntry* ce = thread->last_continuation();
578 RegisterMap map(thread,
579 RegisterMap::UpdateMap::include,
580 RegisterMap::ProcessFrames::skip,
581 RegisterMap::WalkContinuation::skip);
582 map.set_include_argument_oops(false);
583 for (frame f = thread->last_frame(); Continuation::is_frame_in_continuation(ce, f); f = f.sender(&map)) {
584 watermark->assert_is_frame_safe(f);
585 }
586 #endif // ASSERT
587 }
588
589 #ifdef ASSERT
590 static bool monitors_on_stack(JavaThread* thread) {
591 assert_frames_in_continuation_are_safe(thread);
592 ContinuationEntry* ce = thread->last_continuation();
593 RegisterMap map(thread,
594 RegisterMap::UpdateMap::include,
595 RegisterMap::ProcessFrames::skip,
596 RegisterMap::WalkContinuation::skip);
597 map.set_include_argument_oops(false);
598 for (frame f = thread->last_frame(); Continuation::is_frame_in_continuation(ce, f); f = f.sender(&map)) {
599 if ((f.is_interpreted_frame() && ContinuationHelper::InterpretedFrame::is_owning_locks(f)) ||
600 (f.is_compiled_frame() && ContinuationHelper::CompiledFrame::is_owning_locks(map.thread(), &map, f)) ||
601 (f.is_native_frame() && ContinuationHelper::NativeFrame::is_owning_locks(map.thread(), f))) {
602 return true;
603 }
604 }
605 return false;
606 }
607 #endif // ASSERT
608
609 // Called _after_ the last possible safepoint during the freeze operation (chunk allocation)
610 void FreezeBase::unwind_frames() {
611 ContinuationEntry* entry = _cont.entry();
612 entry->flush_stack_processing(_thread);
613 assert_frames_in_continuation_are_safe(_thread);
614 JFR_ONLY(Jfr::check_and_process_sample_request(_thread);)
615 assert(LockingMode != LM_LEGACY || !monitors_on_stack(_thread), "unexpected monitors on stack");
616 set_anchor_to_entry(_thread, entry);
617 }
618
619 template <typename ConfigT>
620 freeze_result Freeze<ConfigT>::try_freeze_fast() {
621 assert(_thread->thread_state() == _thread_in_vm, "");
622 assert(_thread->cont_fastpath(), "");
623
624 DEBUG_ONLY(_fast_freeze_size = size_if_fast_freeze_available();)
625 assert(_fast_freeze_size == 0, "");
626
627 stackChunkOop chunk = allocate_chunk(cont_size() + frame::metadata_words + _monitors_in_lockstack, _cont.argsize() + frame::metadata_words_at_top);
628 if (freeze_fast_new_chunk(chunk)) {
629 return freeze_ok;
630 }
631 if (_thread->has_pending_exception()) {
632 return freeze_exception;
633 }
634
635 // TODO R REMOVE when deopt change is fixed
636 assert(!_thread->cont_fastpath() || _barriers, "");
637 log_develop_trace(continuations)("-- RETRYING SLOW --");
638 return freeze_slow();
639 }
640
641 // Returns size needed if the continuation fits, otherwise 0.
642 int FreezeBase::size_if_fast_freeze_available() {
643 stackChunkOop chunk = _cont.tail();
644 if (chunk == nullptr || chunk->is_gc_mode() || chunk->requires_barriers() || chunk->has_mixed_frames()) {
645 log_develop_trace(continuations)("chunk available %s", chunk == nullptr ? "no chunk" : "chunk requires barriers");
646 return 0;
647 }
648
649 int total_size_needed = cont_size();
650 const int chunk_sp = chunk->sp();
651
652 // argsize can be nonzero if we have a caller, but the caller could be in a non-empty parent chunk,
653 // so we subtract it only if we overlap with the caller, i.e. the current chunk isn't empty.
654 // Consider leaving the chunk's argsize set when emptying it and removing the following branch,
655 // although that would require changing stackChunkOopDesc::is_empty
656 if (!chunk->is_empty()) {
657 total_size_needed -= _cont.argsize() + frame::metadata_words_at_top;
658 }
659
660 total_size_needed += _monitors_in_lockstack;
661
662 int chunk_free_room = chunk_sp - frame::metadata_words_at_bottom;
663 bool available = chunk_free_room >= total_size_needed;
664 log_develop_trace(continuations)("chunk available: %s size: %d argsize: %d top: " INTPTR_FORMAT " bottom: " INTPTR_FORMAT,
665 available ? "yes" : "no" , total_size_needed, _cont.argsize(), p2i(_cont_stack_top), p2i(_cont_stack_bottom));
666 return available ? total_size_needed : 0;
667 }
668
669 void FreezeBase::freeze_fast_existing_chunk() {
670 stackChunkOop chunk = _cont.tail();
671
672 DEBUG_ONLY(_fast_freeze_size = size_if_fast_freeze_available();)
673 assert(_fast_freeze_size > 0, "");
674
675 if (!chunk->is_empty()) { // we are copying into a non-empty chunk
676 DEBUG_ONLY(_empty = false;)
677 DEBUG_ONLY(_orig_chunk_sp = chunk->sp_address();)
678 #ifdef ASSERT
679 {
680 intptr_t* retaddr_slot = (chunk->sp_address()
681 - frame::sender_sp_ret_address_offset());
682 assert(ContinuationHelper::return_address_at(retaddr_slot) == chunk->pc(),
683 "unexpected saved return address");
684 }
685 #endif
686
687 // the chunk's sp before the freeze, adjusted to point beyond the stack-passed arguments in the topmost frame
688 // we overlap; we'll overwrite the chunk's top frame's callee arguments
689 const int chunk_start_sp = chunk->sp() + _cont.argsize() + frame::metadata_words_at_top;
690 assert(chunk_start_sp <= chunk->stack_size(), "sp not pointing into stack");
691
692 // increase max_size by what we're freezing minus the overlap
693 chunk->set_max_thawing_size(chunk->max_thawing_size() + cont_size() - _cont.argsize() - frame::metadata_words_at_top);
694
695 intptr_t* const bottom_sp = _cont_stack_bottom - _cont.argsize() - frame::metadata_words_at_top;
696 assert(bottom_sp == _bottom_address, "");
697 // Because the chunk isn't empty, we know there's a caller in the chunk, therefore the bottom-most frame
698 // should have a return barrier (installed back when we thawed it).
699 #ifdef ASSERT
700 {
701 intptr_t* retaddr_slot = (bottom_sp
702 - frame::sender_sp_ret_address_offset());
703 assert(ContinuationHelper::return_address_at(retaddr_slot)
704 == StubRoutines::cont_returnBarrier(),
705 "should be the continuation return barrier");
706 }
707 #endif
708 // We copy the fp from the chunk back to the stack because it contains some caller data,
709 // including, possibly, an oop that might have gone stale since we thawed.
710 patch_stack_pd(bottom_sp, chunk->sp_address());
711 // we don't patch the return pc at this time, so as not to make the stack unwalkable for async walks
712
713 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA false));
714 } else { // the chunk is empty
715 const int chunk_start_sp = chunk->stack_size();
716
717 DEBUG_ONLY(_empty = true;)
718 DEBUG_ONLY(_orig_chunk_sp = chunk->start_address() + chunk_start_sp;)
719
720 chunk->set_max_thawing_size(cont_size());
721 chunk->set_bottom(chunk_start_sp - _cont.argsize() - frame::metadata_words_at_top);
722 chunk->set_sp(chunk->bottom());
723
724 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA false));
725 }
726 }
727
728 bool FreezeBase::freeze_fast_new_chunk(stackChunkOop chunk) {
729 DEBUG_ONLY(_empty = true;)
730
731 // Install new chunk
732 _cont.set_tail(chunk);
733
734 if (UNLIKELY(chunk == nullptr || !_thread->cont_fastpath() || _barriers)) { // OOME/probably humongous
735 log_develop_trace(continuations)("Retrying slow. Barriers: %d", _barriers);
736 return false;
737 }
738
739 chunk->set_max_thawing_size(cont_size());
740
741 // in a fresh chunk, we freeze *with* the bottom-most frame's stack arguments.
742 // They'll then be stored twice: in the chunk and in the parent chunk's top frame
743 const int chunk_start_sp = cont_size() + frame::metadata_words + _monitors_in_lockstack;
744 assert(chunk_start_sp == chunk->stack_size(), "");
745
746 DEBUG_ONLY(_orig_chunk_sp = chunk->start_address() + chunk_start_sp;)
747
748 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA true));
749
750 return true;
751 }
752
753 void FreezeBase::freeze_fast_copy(stackChunkOop chunk, int chunk_start_sp CONT_JFR_ONLY(COMMA bool chunk_is_allocated)) {
754 assert(chunk != nullptr, "");
755 assert(!chunk->has_mixed_frames(), "");
756 assert(!chunk->is_gc_mode(), "");
757 assert(!chunk->has_bitmap(), "");
758 assert(!chunk->requires_barriers(), "");
759 assert(chunk == _cont.tail(), "");
760
761 // We unwind frames after the last safepoint so that the GC will have found the oops in the frames, but before
762 // writing into the chunk. This is so that an asynchronous stack walk (not at a safepoint) that suspends us here
763 // will either see no continuation on the stack, or a consistent chunk.
764 unwind_frames();
765
766 log_develop_trace(continuations)("freeze_fast start: chunk " INTPTR_FORMAT " size: %d orig sp: %d argsize: %d",
767 p2i((oopDesc*)chunk), chunk->stack_size(), chunk_start_sp, _cont.argsize());
768 assert(chunk_start_sp <= chunk->stack_size(), "");
769 assert(chunk_start_sp >= cont_size(), "no room in the chunk");
770
771 const int chunk_new_sp = chunk_start_sp - cont_size(); // the chunk's new sp, after freeze
772 assert(!(_fast_freeze_size > 0) || (_orig_chunk_sp - (chunk->start_address() + chunk_new_sp)) == (_fast_freeze_size - _monitors_in_lockstack), "");
773
774 intptr_t* chunk_top = chunk->start_address() + chunk_new_sp;
775 #ifdef ASSERT
776 if (!_empty) {
777 intptr_t* retaddr_slot = (_orig_chunk_sp
778 - frame::sender_sp_ret_address_offset());
779 assert(ContinuationHelper::return_address_at(retaddr_slot) == chunk->pc(),
780 "unexpected saved return address");
781 }
782 #endif
783
784 log_develop_trace(continuations)("freeze_fast start: " INTPTR_FORMAT " sp: %d chunk_top: " INTPTR_FORMAT,
785 p2i(chunk->start_address()), chunk_new_sp, p2i(chunk_top));
786 intptr_t* from = _cont_stack_top - frame::metadata_words_at_bottom;
787 intptr_t* to = chunk_top - frame::metadata_words_at_bottom;
788 copy_to_chunk(from, to, cont_size() + frame::metadata_words_at_bottom);
789 // Because we're not patched yet, the chunk is now in a bad state
790
791 // patch return pc of the bottom-most frozen frame (now in the chunk)
792 // with the actual caller's return address
793 intptr_t* chunk_bottom_retaddr_slot = (chunk_top + cont_size()
794 - _cont.argsize()
795 - frame::metadata_words_at_top
796 - frame::sender_sp_ret_address_offset());
797 #ifdef ASSERT
798 if (!_empty) {
799 assert(ContinuationHelper::return_address_at(chunk_bottom_retaddr_slot)
800 == StubRoutines::cont_returnBarrier(),
801 "should be the continuation return barrier");
802 }
803 #endif
804 ContinuationHelper::patch_return_address_at(chunk_bottom_retaddr_slot,
805 chunk->pc());
806
807 // We're always writing to a young chunk, so the GC can't see it until the next safepoint.
808 chunk->set_sp(chunk_new_sp);
809
810 // set chunk->pc to the return address of the topmost frame in the chunk
811 if (_preempt) {
812 // On aarch64/riscv64, the return pc of the top frame won't necessarily be at sp[-1].
813 // Also, on x64, if the top frame is the native wrapper frame, sp[-1] will not
814 // be the pc we used when creating the oopmap. Get the top's frame last pc from
815 // the anchor instead.
816 address last_pc = _last_frame.pc();
817 ContinuationHelper::patch_return_address_at(chunk_top - frame::sender_sp_ret_address_offset(), last_pc);
818 chunk->set_pc(last_pc);
819 } else {
820 chunk->set_pc(ContinuationHelper::return_address_at(
821 _cont_stack_top - frame::sender_sp_ret_address_offset()));
822 }
823
824 if (_monitors_in_lockstack > 0) {
825 freeze_lockstack(chunk);
826 }
827
828 _cont.write();
829
830 log_develop_trace(continuations)("FREEZE CHUNK #" INTPTR_FORMAT " (young)", _cont.hash());
831 LogTarget(Trace, continuations) lt;
832 if (lt.develop_is_enabled()) {
833 LogStream ls(lt);
834 chunk->print_on(true, &ls);
835 }
836
837 // Verification
838 assert(_cont.chunk_invariant(), "");
839 chunk->verify();
840
841 #if CONT_JFR
842 EventContinuationFreezeFast e;
843 if (e.should_commit()) {
844 e.set_id(cast_from_oop<u8>(chunk));
845 DEBUG_ONLY(e.set_allocate(chunk_is_allocated);)
846 e.set_size(cont_size() << LogBytesPerWord);
847 e.commit();
848 }
849 #endif
850 }
851
852 NOINLINE freeze_result FreezeBase::freeze_slow() {
853 #ifdef ASSERT
854 ResourceMark rm;
855 #endif
856
857 log_develop_trace(continuations)("freeze_slow #" INTPTR_FORMAT, _cont.hash());
858 assert(_thread->thread_state() == _thread_in_vm || _thread->thread_state() == _thread_blocked, "");
859
860 #if CONT_JFR
861 EventContinuationFreezeSlow e;
862 if (e.should_commit()) {
863 e.set_id(cast_from_oop<u8>(_cont.continuation()));
864 e.commit();
865 }
866 #endif
867
868 init_rest();
869
870 HandleMark hm(Thread::current());
871
872 frame f = freeze_start_frame();
873
874 LogTarget(Debug, continuations) lt;
875 if (lt.develop_is_enabled()) {
876 LogStream ls(lt);
877 f.print_on(&ls);
878 }
879
880 frame caller; // the frozen caller in the chunk
881 freeze_result res = recurse_freeze(f, caller, 0, false, true);
882
883 if (res == freeze_ok) {
884 finish_freeze(f, caller);
885 _cont.write();
886 }
887
888 return res;
889 }
890
891 frame FreezeBase::freeze_start_frame() {
892 if (LIKELY(!_preempt)) {
893 return freeze_start_frame_yield_stub();
894 } else {
895 return freeze_start_frame_on_preempt();
896 }
897 }
898
899 frame FreezeBase::freeze_start_frame_yield_stub() {
900 frame f = _thread->last_frame();
901 assert(SharedRuntime::cont_doYield_stub()->contains(f.pc()), "must be");
902 f = sender<ContinuationHelper::NonInterpretedUnknownFrame>(f);
903 assert(Continuation::is_frame_in_continuation(_thread->last_continuation(), f), "");
904 return f;
905 }
906
907 frame FreezeBase::freeze_start_frame_on_preempt() {
908 assert(_last_frame.sp() == _thread->last_frame().sp(), "_last_frame should be already initialized");
909 assert(Continuation::is_frame_in_continuation(_thread->last_continuation(), _last_frame), "");
910 return _last_frame;
911 }
912
913 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
914 NOINLINE freeze_result FreezeBase::recurse_freeze(frame& f, frame& caller, int callee_argsize, bool callee_interpreted, bool top) {
915 assert(f.unextended_sp() < _bottom_address, ""); // see recurse_freeze_java_frame
916 assert(f.is_interpreted_frame() || ((top && _preempt) == ContinuationHelper::Frame::is_stub(f.cb()))
917 || ((top && _preempt) == f.is_native_frame()), "");
918
919 if (stack_overflow()) {
920 return freeze_exception;
921 }
922
923 if (f.is_compiled_frame()) {
924 if (UNLIKELY(f.oop_map() == nullptr)) {
925 // special native frame
926 return freeze_pinned_native;
927 }
928 return recurse_freeze_compiled_frame(f, caller, callee_argsize, callee_interpreted);
929 } else if (f.is_interpreted_frame()) {
930 assert(!f.interpreter_frame_method()->is_native() || (top && _preempt), "");
931 return recurse_freeze_interpreted_frame(f, caller, callee_argsize, callee_interpreted);
932 } else if (top && _preempt) {
933 assert(f.is_native_frame() || f.is_runtime_frame(), "");
934 return f.is_native_frame() ? recurse_freeze_native_frame(f, caller) : recurse_freeze_stub_frame(f, caller);
935 } else {
936 // Frame can't be frozen. Most likely the call_stub or upcall_stub
937 // which indicates there are further natives frames up the stack.
938 return freeze_pinned_native;
939 }
940 }
941
942 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
943 // See also StackChunkFrameStream<frame_kind>::frame_size()
944 template<typename FKind>
945 inline freeze_result FreezeBase::recurse_freeze_java_frame(const frame& f, frame& caller, int fsize, int argsize) {
946 assert(FKind::is_instance(f), "");
947
948 assert(fsize > 0, "");
949 assert(argsize >= 0, "");
950 _freeze_size += fsize;
951 NOT_PRODUCT(_frames++;)
952
953 assert(FKind::frame_bottom(f) <= _bottom_address, "");
954
955 // We don't use FKind::frame_bottom(f) == _bottom_address because on x64 there's sometimes an extra word between
956 // enterSpecial and an interpreted frame
957 if (FKind::frame_bottom(f) >= _bottom_address - 1) {
958 return finalize_freeze(f, caller, argsize); // recursion end
959 } else {
960 frame senderf = sender<FKind>(f);
961 assert(FKind::interpreted || senderf.sp() == senderf.unextended_sp(), "");
962 freeze_result result = recurse_freeze(senderf, caller, argsize, FKind::interpreted, false); // recursive call
963 return result;
964 }
965 }
966
967 inline void FreezeBase::before_freeze_java_frame(const frame& f, const frame& caller, int fsize, int argsize, bool is_bottom_frame) {
968 LogTarget(Trace, continuations) lt;
969 if (lt.develop_is_enabled()) {
970 LogStream ls(lt);
971 ls.print_cr("======== FREEZING FRAME interpreted: %d bottom: %d", f.is_interpreted_frame(), is_bottom_frame);
972 ls.print_cr("fsize: %d argsize: %d", fsize, argsize);
973 f.print_value_on(&ls);
974 }
975 assert(caller.is_interpreted_frame() == Interpreter::contains(caller.pc()), "");
976 }
977
978 inline void FreezeBase::after_freeze_java_frame(const frame& hf, bool is_bottom_frame) {
979 LogTarget(Trace, continuations) lt;
980 if (lt.develop_is_enabled()) {
981 LogStream ls(lt);
982 DEBUG_ONLY(hf.print_value_on(&ls);)
983 assert(hf.is_heap_frame(), "should be");
984 DEBUG_ONLY(print_frame_layout(hf, false, &ls);)
985 if (is_bottom_frame) {
986 ls.print_cr("bottom h-frame:");
987 hf.print_on(&ls);
988 }
989 }
990 }
991
992 // The parameter argsize_md includes metadata that has to be part of caller/callee overlap.
993 // See also StackChunkFrameStream<frame_kind>::frame_size()
994 freeze_result FreezeBase::finalize_freeze(const frame& callee, frame& caller, int argsize_md) {
995 int argsize = argsize_md - frame::metadata_words_at_top;
996 assert(callee.is_interpreted_frame()
997 || ContinuationHelper::Frame::is_stub(callee.cb())
998 || callee.cb()->as_nmethod()->is_osr_method()
999 || argsize == _cont.argsize(), "argsize: %d cont.argsize: %d", argsize, _cont.argsize());
1000 log_develop_trace(continuations)("bottom: " INTPTR_FORMAT " count %d size: %d argsize: %d",
1001 p2i(_bottom_address), _frames, _freeze_size << LogBytesPerWord, argsize);
1002
1003 LogTarget(Trace, continuations) lt;
1004
1005 #ifdef ASSERT
1006 bool empty = _cont.is_empty();
1007 log_develop_trace(continuations)("empty: %d", empty);
1008 #endif
1009
1010 stackChunkOop chunk = _cont.tail();
1011
1012 assert(chunk == nullptr || (chunk->max_thawing_size() == 0) == chunk->is_empty(), "");
1013
1014 _freeze_size += frame::metadata_words; // for top frame's metadata
1015
1016 int overlap = 0; // the args overlap the caller -- if there is one in this chunk and is of the same kind
1017 int unextended_sp = -1;
1018 if (chunk != nullptr) {
1019 if (!chunk->is_empty()) {
1020 StackChunkFrameStream<ChunkFrames::Mixed> last(chunk);
1021 unextended_sp = chunk->to_offset(StackChunkFrameStream<ChunkFrames::Mixed>(chunk).unextended_sp());
1022 bool top_interpreted = Interpreter::contains(chunk->pc());
1023 if (callee.is_interpreted_frame() == top_interpreted) {
1024 overlap = argsize_md;
1025 }
1026 } else {
1027 unextended_sp = chunk->stack_size() - frame::metadata_words_at_top;
1028 }
1029 }
1030
1031 log_develop_trace(continuations)("finalize _size: %d overlap: %d unextended_sp: %d", _freeze_size, overlap, unextended_sp);
1032
1033 _freeze_size -= overlap;
1034 assert(_freeze_size >= 0, "");
1035
1036 assert(chunk == nullptr || chunk->is_empty()
1037 || unextended_sp == chunk->to_offset(StackChunkFrameStream<ChunkFrames::Mixed>(chunk).unextended_sp()), "");
1038 assert(chunk != nullptr || unextended_sp < _freeze_size, "");
1039
1040 _freeze_size += _monitors_in_lockstack;
1041
1042 // _barriers can be set to true by an allocation in freeze_fast, in which case the chunk is available
1043 bool allocated_old_in_freeze_fast = _barriers;
1044 assert(!allocated_old_in_freeze_fast || (unextended_sp >= _freeze_size && chunk->is_empty()),
1045 "Chunk allocated in freeze_fast is of insufficient size "
1046 "unextended_sp: %d size: %d is_empty: %d", unextended_sp, _freeze_size, chunk->is_empty());
1047 assert(!allocated_old_in_freeze_fast || (!UseZGC && !UseG1GC), "Unexpected allocation");
1048
1049 DEBUG_ONLY(bool empty_chunk = true);
1050 if (unextended_sp < _freeze_size || chunk->is_gc_mode() || (!allocated_old_in_freeze_fast && chunk->requires_barriers())) {
1051 // ALLOCATE NEW CHUNK
1052
1053 if (lt.develop_is_enabled()) {
1054 LogStream ls(lt);
1055 if (chunk == nullptr) {
1056 ls.print_cr("no chunk");
1057 } else {
1058 ls.print_cr("chunk barriers: %d _size: %d free size: %d",
1059 chunk->requires_barriers(), _freeze_size, chunk->sp() - frame::metadata_words);
1060 chunk->print_on(&ls);
1061 }
1062 }
1063
1064 _freeze_size += overlap; // we're allocating a new chunk, so no overlap
1065 // overlap = 0;
1066
1067 chunk = allocate_chunk_slow(_freeze_size, argsize_md);
1068 if (chunk == nullptr) {
1069 return freeze_exception;
1070 }
1071
1072 // Install new chunk
1073 _cont.set_tail(chunk);
1074 assert(chunk->is_empty(), "");
1075 } else {
1076 // REUSE EXISTING CHUNK
1077 log_develop_trace(continuations)("Reusing chunk mixed: %d empty: %d", chunk->has_mixed_frames(), chunk->is_empty());
1078 if (chunk->is_empty()) {
1079 int sp = chunk->stack_size() - argsize_md;
1080 chunk->set_sp(sp);
1081 chunk->set_bottom(sp);
1082 _freeze_size += overlap;
1083 assert(chunk->max_thawing_size() == 0, "");
1084 } DEBUG_ONLY(else empty_chunk = false;)
1085 }
1086 assert(!chunk->is_gc_mode(), "");
1087 assert(!chunk->has_bitmap(), "");
1088 chunk->set_has_mixed_frames(true);
1089
1090 assert(chunk->requires_barriers() == _barriers, "");
1091 assert(!_barriers || chunk->is_empty(), "");
1092
1093 assert(!chunk->is_empty() || StackChunkFrameStream<ChunkFrames::Mixed>(chunk).is_done(), "");
1094 assert(!chunk->is_empty() || StackChunkFrameStream<ChunkFrames::Mixed>(chunk).to_frame().is_empty(), "");
1095
1096 if (_preempt) {
1097 frame f = _thread->last_frame();
1098 if (f.is_interpreted_frame()) {
1099 // Some platforms do not save the last_sp in the top interpreter frame on VM calls.
1100 // We need it so that on resume we can restore the sp to the right place, since
1101 // thawing might add an alignment word to the expression stack (see finish_thaw()).
1102 // We do it now that we know freezing will be successful.
1103 prepare_freeze_interpreted_top_frame(f);
1104 }
1105 }
1106
1107 // We unwind frames after the last safepoint so that the GC will have found the oops in the frames, but before
1108 // writing into the chunk. This is so that an asynchronous stack walk (not at a safepoint) that suspends us here
1109 // will either see no continuation or a consistent chunk.
1110 unwind_frames();
1111
1112 chunk->set_max_thawing_size(chunk->max_thawing_size() + _freeze_size - _monitors_in_lockstack - frame::metadata_words);
1113
1114 if (lt.develop_is_enabled()) {
1115 LogStream ls(lt);
1116 ls.print_cr("top chunk:");
1117 chunk->print_on(&ls);
1118 }
1119
1120 if (_monitors_in_lockstack > 0) {
1121 freeze_lockstack(chunk);
1122 }
1123
1124 // The topmost existing frame in the chunk; or an empty frame if the chunk is empty
1125 caller = StackChunkFrameStream<ChunkFrames::Mixed>(chunk).to_frame();
1126
1127 DEBUG_ONLY(_last_write = caller.unextended_sp() + (empty_chunk ? argsize_md : overlap);)
1128
1129 assert(chunk->is_in_chunk(_last_write - _freeze_size),
1130 "last_write-size: " INTPTR_FORMAT " start: " INTPTR_FORMAT, p2i(_last_write-_freeze_size), p2i(chunk->start_address()));
1131 #ifdef ASSERT
1132 if (lt.develop_is_enabled()) {
1133 LogStream ls(lt);
1134 ls.print_cr("top hframe before (freeze):");
1135 assert(caller.is_heap_frame(), "should be");
1136 caller.print_on(&ls);
1137 }
1138
1139 assert(!empty || Continuation::is_continuation_entry_frame(callee, nullptr), "");
1140
1141 frame entry = sender(callee);
1142
1143 assert((!empty && Continuation::is_return_barrier_entry(entry.pc())) || (empty && Continuation::is_continuation_enterSpecial(entry)), "");
1144 assert(callee.is_interpreted_frame() || entry.sp() == entry.unextended_sp(), "");
1145 #endif
1146
1147 return freeze_ok_bottom;
1148 }
1149
1150 // After freezing a frame we need to possibly adjust some values related to the caller frame.
1151 void FreezeBase::patch(const frame& f, frame& hf, const frame& caller, bool is_bottom_frame) {
1152 if (is_bottom_frame) {
1153 // If we're the bottom frame, we need to replace the return barrier with the real
1154 // caller's pc.
1155 address last_pc = caller.pc();
1156 assert((last_pc == nullptr) == _cont.tail()->is_empty(), "");
1157 ContinuationHelper::Frame::patch_pc(caller, last_pc);
1158 } else {
1159 assert(!caller.is_empty(), "");
1160 }
1161
1162 patch_pd(hf, caller, is_bottom_frame);
1163
1164 if (f.is_interpreted_frame()) {
1165 assert(hf.is_heap_frame(), "should be");
1166 ContinuationHelper::InterpretedFrame::patch_sender_sp(hf, caller);
1167 }
1168
1169 #ifdef ASSERT
1170 if (hf.is_compiled_frame()) {
1171 if (f.is_deoptimized_frame()) { // TODO DEOPT: long term solution: unroll on freeze and patch pc
1172 log_develop_trace(continuations)("Freezing deoptimized frame");
1173 assert(f.cb()->as_nmethod()->is_deopt_pc(f.raw_pc()), "");
1174 assert(f.cb()->as_nmethod()->is_deopt_pc(ContinuationHelper::Frame::real_pc(f)), "");
1175 }
1176 }
1177 #endif
1178 }
1179
1180 #ifdef ASSERT
1181 static void verify_frame_top(const frame& f, intptr_t* top) {
1182 ResourceMark rm;
1183 InterpreterOopMap mask;
1184 f.interpreted_frame_oop_map(&mask);
1185 assert(top <= ContinuationHelper::InterpretedFrame::frame_top(f, &mask),
1186 "frame_top: " INTPTR_FORMAT " Interpreted::frame_top: " INTPTR_FORMAT,
1187 p2i(top), p2i(ContinuationHelper::InterpretedFrame::frame_top(f, &mask)));
1188 }
1189 #endif // ASSERT
1190
1191 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
1192 // See also StackChunkFrameStream<frame_kind>::frame_size()
1193 NOINLINE freeze_result FreezeBase::recurse_freeze_interpreted_frame(frame& f, frame& caller,
1194 int callee_argsize /* incl. metadata */,
1195 bool callee_interpreted) {
1196 adjust_interpreted_frame_unextended_sp(f);
1197
1198 // The frame's top never includes the stack arguments to the callee
1199 intptr_t* const stack_frame_top = ContinuationHelper::InterpretedFrame::frame_top(f, callee_argsize, callee_interpreted);
1200 intptr_t* const stack_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(f);
1201 const int fsize = pointer_delta_as_int(stack_frame_bottom, stack_frame_top);
1202
1203 DEBUG_ONLY(verify_frame_top(f, stack_frame_top));
1204
1205 Method* frame_method = ContinuationHelper::Frame::frame_method(f);
1206 // including metadata between f and its args
1207 const int argsize = ContinuationHelper::InterpretedFrame::stack_argsize(f) + frame::metadata_words_at_top;
1208
1209 log_develop_trace(continuations)("recurse_freeze_interpreted_frame %s _size: %d fsize: %d argsize: %d callee_interpreted: %d",
1210 frame_method->name_and_sig_as_C_string(), _freeze_size, fsize, argsize, callee_interpreted);
1211 // we'd rather not yield inside methods annotated with @JvmtiMountTransition
1212 assert(!ContinuationHelper::Frame::frame_method(f)->jvmti_mount_transition(), "");
1213
1214 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::InterpretedFrame>(f, caller, fsize, argsize);
1215 if (UNLIKELY(result > freeze_ok_bottom)) {
1216 return result;
1217 }
1218
1219 bool is_bottom_frame = result == freeze_ok_bottom;
1220 assert(!caller.is_empty() || is_bottom_frame, "");
1221
1222 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, 0, is_bottom_frame);)
1223
1224 frame hf = new_heap_frame<ContinuationHelper::InterpretedFrame>(f, caller);
1225 _total_align_size += frame::align_wiggle; // add alignment room for internal interpreted frame alignment on AArch64/PPC64
1226
1227 intptr_t* heap_frame_top = ContinuationHelper::InterpretedFrame::frame_top(hf, callee_argsize, callee_interpreted);
1228 intptr_t* heap_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(hf);
1229 assert(heap_frame_bottom == heap_frame_top + fsize, "");
1230
1231 // Some architectures (like AArch64/PPC64/RISC-V) add padding between the locals and the fixed_frame to keep the fp 16-byte-aligned.
1232 // On those architectures we freeze the padding in order to keep the same fp-relative offsets in the fixed_frame.
1233 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1234 assert(!is_bottom_frame || !caller.is_interpreted_frame() || (heap_frame_top + fsize) == (caller.unextended_sp() + argsize), "");
1235
1236 relativize_interpreted_frame_metadata(f, hf);
1237
1238 patch(f, hf, caller, is_bottom_frame);
1239
1240 CONT_JFR_ONLY(_jfr_info.record_interpreted_frame();)
1241 DEBUG_ONLY(after_freeze_java_frame(hf, is_bottom_frame);)
1242 caller = hf;
1243
1244 // Mark frame_method's GC epoch for class redefinition on_stack calculation.
1245 frame_method->record_gc_epoch();
1246
1247 return freeze_ok;
1248 }
1249
1250 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
1251 // See also StackChunkFrameStream<frame_kind>::frame_size()
1252 freeze_result FreezeBase::recurse_freeze_compiled_frame(frame& f, frame& caller,
1253 int callee_argsize /* incl. metadata */,
1254 bool callee_interpreted) {
1255 // The frame's top never includes the stack arguments to the callee
1256 intptr_t* const stack_frame_top = ContinuationHelper::CompiledFrame::frame_top(f, callee_argsize, callee_interpreted);
1257 intptr_t* const stack_frame_bottom = ContinuationHelper::CompiledFrame::frame_bottom(f);
1258 // including metadata between f and its stackargs
1259 int argsize = ContinuationHelper::CompiledFrame::stack_argsize(f) + frame::metadata_words_at_top;
1260 int fsize = pointer_delta_as_int(stack_frame_bottom + argsize, stack_frame_top);
1261
1262 int real_frame_size = 0;
1263 bool augmented = f.was_augmented_on_entry(real_frame_size);
1264 if (augmented) {
1265 // The args reside inside the frame so clear argsize. If the caller is compiled,
1266 // this will cause the stack arguments passed by the caller to be freezed when
1267 // freezing the caller frame itself. If the caller is interpreted this will have
1268 // the effect of discarding the arg area created in the i2c stub.
1269 argsize = 0;
1270 fsize = real_frame_size - (callee_interpreted ? 0 : callee_argsize);
1271 #ifdef ASSERT
1272 nmethod* nm = f.cb()->as_nmethod();
1273 Method* method = nm->method();
1274 address return_pc = ContinuationHelper::CompiledFrame::return_pc(f);
1275 CodeBlob* caller_cb = CodeCache::find_blob_fast(return_pc);
1276 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");
1277 assert((!caller_cb->is_nmethod() && nm->is_compiled_by_c2()) ||
1278 (nm->compiler_type() != caller_cb->as_nmethod()->compiler_type()) ||
1279 (nm->is_compiled_by_c2() && !method->is_static() && method->method_holder()->is_inline_klass()),
1280 "frame should not be extended");
1281 #endif
1282 }
1283
1284 log_develop_trace(continuations)("recurse_freeze_compiled_frame %s _size: %d fsize: %d argsize: %d augmented: %d",
1285 ContinuationHelper::Frame::frame_method(f) != nullptr ?
1286 ContinuationHelper::Frame::frame_method(f)->name_and_sig_as_C_string() : "",
1287 _freeze_size, fsize, argsize, augmented);
1288 // we'd rather not yield inside methods annotated with @JvmtiMountTransition
1289 assert(!ContinuationHelper::Frame::frame_method(f)->jvmti_mount_transition(), "");
1290
1291 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::CompiledFrame>(f, caller, fsize, argsize);
1292 if (UNLIKELY(result > freeze_ok_bottom)) {
1293 return result;
1294 }
1295
1296 bool is_bottom_frame = result == freeze_ok_bottom;
1297 assert(!caller.is_empty() || is_bottom_frame, "");
1298 assert(!is_bottom_frame || !augmented, "thaw extended frame without caller?");
1299
1300 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, argsize, is_bottom_frame);)
1301
1302 frame hf = new_heap_frame<ContinuationHelper::CompiledFrame>(f, caller, augmented ? real_frame_size - f.cb()->as_nmethod()->frame_size() : 0);
1303
1304 intptr_t* heap_frame_top = ContinuationHelper::CompiledFrame::frame_top(hf, callee_argsize, callee_interpreted);
1305
1306 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1307 assert(!is_bottom_frame || !caller.is_compiled_frame() || (heap_frame_top + fsize) == (caller.unextended_sp() + argsize), "");
1308
1309 if (caller.is_interpreted_frame()) {
1310 // When thawing the frame we might need to add alignment (see Thaw::align)
1311 _total_align_size += frame::align_wiggle;
1312 }
1313
1314 patch(f, hf, caller, is_bottom_frame);
1315
1316 assert(is_bottom_frame || Interpreter::contains(ContinuationHelper::CompiledFrame::real_pc(caller)) == caller.is_interpreted_frame(), "");
1317
1318 DEBUG_ONLY(after_freeze_java_frame(hf, is_bottom_frame);)
1319 caller = hf;
1320 return freeze_ok;
1321 }
1322
1323 NOINLINE freeze_result FreezeBase::recurse_freeze_stub_frame(frame& f, frame& caller) {
1324 DEBUG_ONLY(frame fsender = sender(f);)
1325 assert(fsender.is_compiled_frame(), "sender should be compiled frame");
1326
1327 intptr_t* const stack_frame_top = ContinuationHelper::StubFrame::frame_top(f);
1328 const int fsize = f.cb()->frame_size();
1329
1330 log_develop_trace(continuations)("recurse_freeze_stub_frame %s _size: %d fsize: %d :: " INTPTR_FORMAT " - " INTPTR_FORMAT,
1331 f.cb()->name(), _freeze_size, fsize, p2i(stack_frame_top), p2i(stack_frame_top+fsize));
1332
1333 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::StubFrame>(f, caller, fsize, 0);
1334 if (UNLIKELY(result > freeze_ok_bottom)) {
1335 return result;
1336 }
1337
1338 assert(result == freeze_ok, "should have caller");
1339 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, 0, false /*is_bottom_frame*/);)
1340
1341 frame hf = new_heap_frame<ContinuationHelper::StubFrame>(f, caller);
1342 intptr_t* heap_frame_top = ContinuationHelper::StubFrame::frame_top(hf);
1343
1344 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1345
1346 patch(f, hf, caller, false /*is_bottom_frame*/);
1347
1348 DEBUG_ONLY(after_freeze_java_frame(hf, false /*is_bottom_frame*/);)
1349
1350 caller = hf;
1351 return freeze_ok;
1352 }
1353
1354 NOINLINE freeze_result FreezeBase::recurse_freeze_native_frame(frame& f, frame& caller) {
1355 if (!f.cb()->as_nmethod()->method()->is_object_wait0()) {
1356 assert(f.cb()->as_nmethod()->method()->is_synchronized(), "");
1357 // Synchronized native method case. Unlike the interpreter native wrapper, the compiled
1358 // native wrapper tries to acquire the monitor after marshalling the arguments from the
1359 // caller into the native convention. This is so that we have a valid oopMap in case of
1360 // having to block in the slow path. But that would require freezing those registers too
1361 // and then fixing them back on thaw in case of oops. To avoid complicating things and
1362 // given that this would be a rare case anyways just pin the vthread to the carrier.
1363 return freeze_pinned_native;
1364 }
1365
1366 intptr_t* const stack_frame_top = ContinuationHelper::NativeFrame::frame_top(f);
1367 // There are no stackargs but argsize must include the metadata
1368 const int argsize = frame::metadata_words_at_top;
1369 const int fsize = f.cb()->frame_size() + argsize;
1370
1371 log_develop_trace(continuations)("recurse_freeze_native_frame %s _size: %d fsize: %d :: " INTPTR_FORMAT " - " INTPTR_FORMAT,
1372 f.cb()->name(), _freeze_size, fsize, p2i(stack_frame_top), p2i(stack_frame_top+fsize));
1373
1374 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::NativeFrame>(f, caller, fsize, argsize);
1375 if (UNLIKELY(result > freeze_ok_bottom)) {
1376 return result;
1377 }
1378
1379 assert(result == freeze_ok, "should have caller frame");
1380 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, argsize, false /* is_bottom_frame */);)
1381
1382 frame hf = new_heap_frame<ContinuationHelper::NativeFrame>(f, caller);
1383 intptr_t* heap_frame_top = ContinuationHelper::NativeFrame::frame_top(hf);
1384
1385 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1386
1387 if (caller.is_interpreted_frame()) {
1388 // When thawing the frame we might need to add alignment (see Thaw::align)
1389 _total_align_size += frame::align_wiggle;
1390 }
1391
1392 patch(f, hf, caller, false /* is_bottom_frame */);
1393
1394 DEBUG_ONLY(after_freeze_java_frame(hf, false /* is_bottom_frame */);)
1395
1396 caller = hf;
1397 return freeze_ok;
1398 }
1399
1400 NOINLINE void FreezeBase::finish_freeze(const frame& f, const frame& top) {
1401 stackChunkOop chunk = _cont.tail();
1402
1403 LogTarget(Trace, continuations) lt;
1404 if (lt.develop_is_enabled()) {
1405 LogStream ls(lt);
1406 assert(top.is_heap_frame(), "should be");
1407 top.print_on(&ls);
1408 }
1409
1410 set_top_frame_metadata_pd(top);
1411
1412 chunk->set_sp(chunk->to_offset(top.sp()));
1413 chunk->set_pc(top.pc());
1414
1415 chunk->set_max_thawing_size(chunk->max_thawing_size() + _total_align_size);
1416
1417 assert(chunk->sp_address() - chunk->start_address() >= _monitors_in_lockstack, "clash with lockstack");
1418
1419 // At this point the chunk is consistent
1420
1421 if (UNLIKELY(_barriers)) {
1422 log_develop_trace(continuations)("do barriers on old chunk");
1423 // Serial and Parallel GC can allocate objects directly into the old generation.
1424 // Then we want to relativize the derived pointers eagerly so that
1425 // old chunks are all in GC mode.
1426 assert(!UseG1GC, "G1 can not deal with allocating outside of eden");
1427 assert(!UseZGC, "ZGC can not deal with allocating chunks visible to marking");
1428 if (UseShenandoahGC) {
1429 _cont.tail()->relativize_derived_pointers_concurrently();
1430 } else {
1431 ContinuationGCSupport::transform_stack_chunk(_cont.tail());
1432 }
1433 // For objects in the old generation we must maintain the remembered set
1434 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>();
1435 }
1436
1437 log_develop_trace(continuations)("finish_freeze: has_mixed_frames: %d", chunk->has_mixed_frames());
1438 if (lt.develop_is_enabled()) {
1439 LogStream ls(lt);
1440 chunk->print_on(true, &ls);
1441 }
1442
1443 if (lt.develop_is_enabled()) {
1444 LogStream ls(lt);
1445 ls.print_cr("top hframe after (freeze):");
1446 assert(_cont.last_frame().is_heap_frame(), "should be");
1447 _cont.last_frame().print_on(&ls);
1448 DEBUG_ONLY(print_frame_layout(top, false, &ls);)
1449 }
1450
1451 assert(_cont.chunk_invariant(), "");
1452 }
1453
1454 inline bool FreezeBase::stack_overflow() { // detect stack overflow in recursive native code
1455 JavaThread* t = !_preempt ? _thread : JavaThread::current();
1456 assert(t == JavaThread::current(), "");
1457 if (os::current_stack_pointer() < t->stack_overflow_state()->shadow_zone_safe_limit()) {
1458 if (!_preempt) {
1459 ContinuationWrapper::SafepointOp so(t, _cont); // could also call _cont.done() instead
1460 Exceptions::_throw_msg(t, __FILE__, __LINE__, vmSymbols::java_lang_StackOverflowError(), "Stack overflow while freezing");
1461 }
1462 return true;
1463 }
1464 return false;
1465 }
1466
1467 class StackChunkAllocator : public MemAllocator {
1468 const size_t _stack_size;
1469 int _argsize_md;
1470 ContinuationWrapper& _continuation_wrapper;
1471 JvmtiSampledObjectAllocEventCollector* const _jvmti_event_collector;
1472 mutable bool _took_slow_path;
1473
1474 // Does the minimal amount of initialization needed for a TLAB allocation.
1475 // We don't need to do a full initialization, as such an allocation need not be immediately walkable.
1476 virtual oop initialize(HeapWord* mem) const override {
1477 assert(_stack_size > 0, "");
1478 assert(_stack_size <= max_jint, "");
1479 assert(_word_size > _stack_size, "");
1480
1481 // zero out fields (but not the stack)
1482 const size_t hs = oopDesc::header_size();
1483 if (oopDesc::has_klass_gap()) {
1484 oopDesc::set_klass_gap(mem, 0);
1485 }
1486 Copy::fill_to_aligned_words(mem + hs, vmClasses::StackChunk_klass()->size_helper() - hs);
1487
1488 int bottom = (int)_stack_size - _argsize_md;
1489
1490 jdk_internal_vm_StackChunk::set_size(mem, (int)_stack_size);
1491 jdk_internal_vm_StackChunk::set_bottom(mem, bottom);
1492 jdk_internal_vm_StackChunk::set_sp(mem, bottom);
1493
1494 return finish(mem);
1495 }
1496
1497 stackChunkOop allocate_fast() const {
1498 if (!UseTLAB) {
1499 return nullptr;
1500 }
1501
1502 HeapWord* const mem = MemAllocator::mem_allocate_inside_tlab_fast();
1503 if (mem == nullptr) {
1504 return nullptr;
1505 }
1506
1507 oop obj = initialize(mem);
1508 return stackChunkOopDesc::cast(obj);
1509 }
1510
1511 public:
1512 StackChunkAllocator(Klass* klass,
1513 size_t word_size,
1514 Thread* thread,
1515 size_t stack_size,
1516 int argsize_md,
1517 ContinuationWrapper& continuation_wrapper,
1518 JvmtiSampledObjectAllocEventCollector* jvmti_event_collector)
1519 : MemAllocator(klass, word_size, thread),
1520 _stack_size(stack_size),
1521 _argsize_md(argsize_md),
1522 _continuation_wrapper(continuation_wrapper),
1523 _jvmti_event_collector(jvmti_event_collector),
1524 _took_slow_path(false) {}
1525
1526 // Provides it's own, specialized allocation which skips instrumentation
1527 // if the memory can be allocated without going to a slow-path.
1528 stackChunkOop allocate() const {
1529 // First try to allocate without any slow-paths or instrumentation.
1530 stackChunkOop obj = allocate_fast();
1531 if (obj != nullptr) {
1532 return obj;
1533 }
1534
1535 // Now try full-blown allocation with all expensive operations,
1536 // including potentially safepoint operations.
1537 _took_slow_path = true;
1538
1539 // Protect unhandled Loom oops
1540 ContinuationWrapper::SafepointOp so(_thread, _continuation_wrapper);
1541
1542 // Can safepoint
1543 _jvmti_event_collector->start();
1544
1545 // Can safepoint
1546 return stackChunkOopDesc::cast(MemAllocator::allocate());
1547 }
1548
1549 bool took_slow_path() const {
1550 return _took_slow_path;
1551 }
1552 };
1553
1554 template <typename ConfigT>
1555 stackChunkOop Freeze<ConfigT>::allocate_chunk(size_t stack_size, int argsize_md) {
1556 log_develop_trace(continuations)("allocate_chunk allocating new chunk");
1557
1558 InstanceStackChunkKlass* klass = InstanceStackChunkKlass::cast(vmClasses::StackChunk_klass());
1559 size_t size_in_words = klass->instance_size(stack_size);
1560
1561 if (CollectedHeap::stack_chunk_max_size() > 0 && size_in_words >= CollectedHeap::stack_chunk_max_size()) {
1562 if (!_preempt) {
1563 throw_stack_overflow_on_humongous_chunk();
1564 }
1565 return nullptr;
1566 }
1567
1568 JavaThread* current = _preempt ? JavaThread::current() : _thread;
1569 assert(current == JavaThread::current(), "should be current");
1570
1571 // Allocate the chunk.
1572 //
1573 // This might safepoint while allocating, but all safepointing due to
1574 // instrumentation have been deferred. This property is important for
1575 // some GCs, as this ensures that the allocated object is in the young
1576 // generation / newly allocated memory.
1577 StackChunkAllocator allocator(klass, size_in_words, current, stack_size, argsize_md, _cont, _jvmti_event_collector);
1578 stackChunkOop chunk = allocator.allocate();
1579
1580 if (chunk == nullptr) {
1581 return nullptr; // OOME
1582 }
1583
1584 // assert that chunk is properly initialized
1585 assert(chunk->stack_size() == (int)stack_size, "");
1586 assert(chunk->size() >= stack_size, "chunk->size(): %zu size: %zu", chunk->size(), stack_size);
1587 assert(chunk->sp() == chunk->bottom(), "");
1588 assert((intptr_t)chunk->start_address() % 8 == 0, "");
1589 assert(chunk->max_thawing_size() == 0, "");
1590 assert(chunk->pc() == nullptr, "");
1591 assert(chunk->is_empty(), "");
1592 assert(chunk->flags() == 0, "");
1593 assert(chunk->is_gc_mode() == false, "");
1594 assert(chunk->lockstack_size() == 0, "");
1595
1596 // fields are uninitialized
1597 chunk->set_parent_access<IS_DEST_UNINITIALIZED>(_cont.last_nonempty_chunk());
1598 chunk->set_cont_access<IS_DEST_UNINITIALIZED>(_cont.continuation());
1599
1600 #if INCLUDE_ZGC
1601 if (UseZGC) {
1602 ZStackChunkGCData::initialize(chunk);
1603 assert(!chunk->requires_barriers(), "ZGC always allocates in the young generation");
1604 _barriers = false;
1605 } else
1606 #endif
1607 #if INCLUDE_SHENANDOAHGC
1608 if (UseShenandoahGC) {
1609 _barriers = chunk->requires_barriers();
1610 } else
1611 #endif
1612 {
1613 if (!allocator.took_slow_path()) {
1614 // Guaranteed to be in young gen / newly allocated memory
1615 assert(!chunk->requires_barriers(), "Unfamiliar GC requires barriers on TLAB allocation");
1616 _barriers = false;
1617 } else {
1618 // Some GCs could put direct allocations in old gen for slow-path
1619 // allocations; need to explicitly check if that was the case.
1620 _barriers = chunk->requires_barriers();
1621 }
1622 }
1623
1624 if (_barriers) {
1625 log_develop_trace(continuations)("allocation requires barriers");
1626 }
1627
1628 assert(chunk->parent() == nullptr || chunk->parent()->is_stackChunk(), "");
1629
1630 return chunk;
1631 }
1632
1633 void FreezeBase::throw_stack_overflow_on_humongous_chunk() {
1634 ContinuationWrapper::SafepointOp so(_thread, _cont); // could also call _cont.done() instead
1635 Exceptions::_throw_msg(_thread, __FILE__, __LINE__, vmSymbols::java_lang_StackOverflowError(), "Humongous stack chunk");
1636 }
1637
1638 #if INCLUDE_JVMTI
1639 static int num_java_frames(ContinuationWrapper& cont) {
1640 ResourceMark rm; // used for scope traversal in num_java_frames(nmethod*, address)
1641 int count = 0;
1642 for (stackChunkOop chunk = cont.tail(); chunk != nullptr; chunk = chunk->parent()) {
1643 count += chunk->num_java_frames();
1644 }
1645 return count;
1646 }
1647
1648 static void invalidate_jvmti_stack(JavaThread* thread) {
1649 if (thread->is_interp_only_mode()) {
1650 JvmtiThreadState *state = thread->jvmti_thread_state();
1651 if (state != nullptr)
1652 state->invalidate_cur_stack_depth();
1653 }
1654 }
1655
1656 static void jvmti_yield_cleanup(JavaThread* thread, ContinuationWrapper& cont) {
1657 if (JvmtiExport::can_post_frame_pop()) {
1658 int num_frames = num_java_frames(cont);
1659
1660 ContinuationWrapper::SafepointOp so(Thread::current(), cont);
1661 JvmtiExport::continuation_yield_cleanup(JavaThread::current(), num_frames);
1662 }
1663 invalidate_jvmti_stack(thread);
1664 }
1665
1666 static void jvmti_mount_end(JavaThread* current, ContinuationWrapper& cont, frame top) {
1667 assert(current->vthread() != nullptr, "must be");
1668
1669 HandleMarkCleaner hm(current);
1670 Handle vth(current, current->vthread());
1671
1672 ContinuationWrapper::SafepointOp so(current, cont);
1673
1674 // Since we might safepoint set the anchor so that the stack can be walked.
1675 set_anchor(current, top.sp());
1676
1677 JRT_BLOCK
1678 JvmtiVTMSTransitionDisabler::VTMS_vthread_mount((jthread)vth.raw_value(), false);
1679
1680 if (current->pending_contended_entered_event()) {
1681 JvmtiExport::post_monitor_contended_entered(current, current->contended_entered_monitor());
1682 current->set_contended_entered_monitor(nullptr);
1683 }
1684 JRT_BLOCK_END
1685
1686 clear_anchor(current);
1687 }
1688 #endif // INCLUDE_JVMTI
1689
1690 #ifdef ASSERT
1691 // There are no interpreted frames if we're not called from the interpreter and we haven't ancountered an i2c
1692 // adapter or called Deoptimization::unpack_frames. As for native frames, upcalls from JNI also go through the
1693 // interpreter (see JavaCalls::call_helper), while the UpcallLinker explicitly sets cont_fastpath.
1694 bool FreezeBase::check_valid_fast_path() {
1695 ContinuationEntry* ce = _thread->last_continuation();
1696 RegisterMap map(_thread,
1697 RegisterMap::UpdateMap::skip,
1698 RegisterMap::ProcessFrames::skip,
1699 RegisterMap::WalkContinuation::skip);
1700 map.set_include_argument_oops(false);
1701 bool is_top_frame = true;
1702 for (frame f = freeze_start_frame(); Continuation::is_frame_in_continuation(ce, f); f = f.sender(&map), is_top_frame = false) {
1703 if (!((f.is_compiled_frame() && !f.is_deoptimized_frame()) || (is_top_frame && (f.is_runtime_frame() || f.is_native_frame())))) {
1704 return false;
1705 }
1706 }
1707 return true;
1708 }
1709 #endif // ASSERT
1710
1711 static inline freeze_result freeze_epilog(ContinuationWrapper& cont) {
1712 verify_continuation(cont.continuation());
1713 assert(!cont.is_empty(), "");
1714
1715 log_develop_debug(continuations)("=== End of freeze cont ### #" INTPTR_FORMAT, cont.hash());
1716 return freeze_ok;
1717 }
1718
1719 static freeze_result freeze_epilog(JavaThread* thread, ContinuationWrapper& cont, freeze_result res) {
1720 if (UNLIKELY(res != freeze_ok)) {
1721 JFR_ONLY(thread->set_last_freeze_fail_result(res);)
1722 verify_continuation(cont.continuation());
1723 log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1724 return res;
1725 }
1726
1727 JVMTI_ONLY(jvmti_yield_cleanup(thread, cont)); // can safepoint
1728 return freeze_epilog(cont);
1729 }
1730
1731 static freeze_result preempt_epilog(ContinuationWrapper& cont, freeze_result res, frame& old_last_frame) {
1732 if (UNLIKELY(res != freeze_ok)) {
1733 verify_continuation(cont.continuation());
1734 log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1735 return res;
1736 }
1737
1738 patch_return_pc_with_preempt_stub(old_last_frame);
1739 cont.tail()->set_preempted(true);
1740
1741 return freeze_epilog(cont);
1742 }
1743
1744 template<typename ConfigT, bool preempt>
1745 static inline freeze_result freeze_internal(JavaThread* current, intptr_t* const sp) {
1746 assert(!current->has_pending_exception(), "");
1747
1748 #ifdef ASSERT
1749 log_trace(continuations)("~~~~ freeze sp: " INTPTR_FORMAT "JavaThread: " INTPTR_FORMAT, p2i(current->last_continuation()->entry_sp()), p2i(current));
1750 log_frames(current);
1751 #endif
1752
1753 CONT_JFR_ONLY(EventContinuationFreeze event;)
1754
1755 ContinuationEntry* entry = current->last_continuation();
1756
1757 oop oopCont = entry->cont_oop(current);
1758 assert(oopCont == current->last_continuation()->cont_oop(current), "");
1759 assert(ContinuationEntry::assert_entry_frame_laid_out(current), "");
1760
1761 verify_continuation(oopCont);
1762 ContinuationWrapper cont(current, oopCont);
1763 log_develop_debug(continuations)("FREEZE #" INTPTR_FORMAT " " INTPTR_FORMAT, cont.hash(), p2i((oopDesc*)oopCont));
1764
1765 assert(entry->is_virtual_thread() == (entry->scope(current) == java_lang_VirtualThread::vthread_scope()), "");
1766
1767 assert(LockingMode == LM_LEGACY || (current->held_monitor_count() == 0 && current->jni_monitor_count() == 0),
1768 "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());
1769
1770 if (entry->is_pinned() || current->held_monitor_count() > 0) {
1771 log_develop_debug(continuations)("PINNED due to critical section/hold monitor");
1772 verify_continuation(cont.continuation());
1773 freeze_result res = entry->is_pinned() ? freeze_pinned_cs : freeze_pinned_monitor;
1774 if (!preempt) {
1775 JFR_ONLY(current->set_last_freeze_fail_result(res);)
1776 }
1777 log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1778 // Avoid Thread.yield() loops without safepoint polls.
1779 if (SafepointMechanism::should_process(current) && !preempt) {
1780 cont.done(); // allow safepoint
1781 ThreadInVMfromJava tivmfj(current);
1782 }
1783 return res;
1784 }
1785
1786 Freeze<ConfigT> freeze(current, cont, sp, preempt);
1787
1788 assert(!current->cont_fastpath() || freeze.check_valid_fast_path(), "");
1789 bool fast = UseContinuationFastPath && current->cont_fastpath();
1790 if (fast && freeze.size_if_fast_freeze_available() > 0) {
1791 freeze.freeze_fast_existing_chunk();
1792 CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1793 return !preempt ? freeze_epilog(cont) : preempt_epilog(cont, freeze_ok, freeze.last_frame());
1794 }
1795
1796 if (preempt) {
1797 JvmtiSampledObjectAllocEventCollector jsoaec(false);
1798 freeze.set_jvmti_event_collector(&jsoaec);
1799
1800 freeze_result res = fast ? freeze.try_freeze_fast() : freeze.freeze_slow();
1801
1802 CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1803 preempt_epilog(cont, res, freeze.last_frame());
1804 return res;
1805 }
1806
1807 log_develop_trace(continuations)("chunk unavailable; transitioning to VM");
1808 assert(current == JavaThread::current(), "must be current thread");
1809 JRT_BLOCK
1810 // delays a possible JvmtiSampledObjectAllocEventCollector in alloc_chunk
1811 JvmtiSampledObjectAllocEventCollector jsoaec(false);
1812 freeze.set_jvmti_event_collector(&jsoaec);
1813
1814 freeze_result res = fast ? freeze.try_freeze_fast() : freeze.freeze_slow();
1815
1816 CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1817 freeze_epilog(current, cont, res);
1818 cont.done(); // allow safepoint in the transition back to Java
1819 return res;
1820 JRT_BLOCK_END
1821 }
1822
1823 static freeze_result is_pinned0(JavaThread* thread, oop cont_scope, bool safepoint) {
1824 ContinuationEntry* entry = thread->last_continuation();
1825 if (entry == nullptr) {
1826 return freeze_ok;
1827 }
1828 if (entry->is_pinned()) {
1829 return freeze_pinned_cs;
1830 } else if (thread->held_monitor_count() > 0) {
1831 return freeze_pinned_monitor;
1832 }
1833
1834 RegisterMap map(thread,
1835 RegisterMap::UpdateMap::include,
1836 RegisterMap::ProcessFrames::skip,
1837 RegisterMap::WalkContinuation::skip);
1838 map.set_include_argument_oops(false);
1839 frame f = thread->last_frame();
1840
1841 if (!safepoint) {
1842 f = f.sender(&map); // this is the yield frame
1843 } else { // safepoint yield
1844 #if (defined(X86) || defined(AARCH64) || defined(RISCV64)) && !defined(ZERO)
1845 f.set_fp(f.real_fp()); // Instead of this, maybe in ContinuationWrapper::set_last_frame always use the real_fp?
1846 #else
1847 Unimplemented();
1848 #endif
1849 if (!Interpreter::contains(f.pc())) {
1850 assert(ContinuationHelper::Frame::is_stub(f.cb()), "must be");
1851 assert(f.oop_map() != nullptr, "must be");
1852 f.oop_map()->update_register_map(&f, &map); // we have callee-save registers in this case
1853 }
1854 }
1855
1856 while (true) {
1857 if ((f.is_interpreted_frame() && f.interpreter_frame_method()->is_native()) || f.is_native_frame()) {
1858 return freeze_pinned_native;
1859 }
1860
1861 f = f.sender(&map);
1862 if (!Continuation::is_frame_in_continuation(entry, f)) {
1863 oop scope = jdk_internal_vm_Continuation::scope(entry->cont_oop(thread));
1864 if (scope == cont_scope) {
1865 break;
1866 }
1867 intx monitor_count = entry->parent_held_monitor_count();
1868 entry = entry->parent();
1869 if (entry == nullptr) {
1870 break;
1871 }
1872 if (entry->is_pinned()) {
1873 return freeze_pinned_cs;
1874 } else if (monitor_count > 0) {
1875 return freeze_pinned_monitor;
1876 }
1877 }
1878 }
1879 return freeze_ok;
1880 }
1881
1882 /////////////// THAW ////
1883
1884 static int thaw_size(stackChunkOop chunk) {
1885 int size = chunk->max_thawing_size();
1886 size += frame::metadata_words; // For the top pc+fp in push_return_frame or top = stack_sp - frame::metadata_words in thaw_fast
1887 size += 2*frame::align_wiggle; // in case of alignments at the top and bottom
1888 return size;
1889 }
1890
1891 // make room on the stack for thaw
1892 // returns the size in bytes, or 0 on failure
1893 static inline int prepare_thaw_internal(JavaThread* thread, bool return_barrier) {
1894 log_develop_trace(continuations)("~~~~ prepare_thaw return_barrier: %d", return_barrier);
1895
1896 assert(thread == JavaThread::current(), "");
1897
1898 ContinuationEntry* ce = thread->last_continuation();
1899 assert(ce != nullptr, "");
1900 oop continuation = ce->cont_oop(thread);
1901 assert(continuation == get_continuation(thread), "");
1902 verify_continuation(continuation);
1903
1904 stackChunkOop chunk = jdk_internal_vm_Continuation::tail(continuation);
1905 assert(chunk != nullptr, "");
1906
1907 // The tail can be empty because it might still be available for another freeze.
1908 // However, here we want to thaw, so we get rid of it (it will be GCed).
1909 if (UNLIKELY(chunk->is_empty())) {
1910 chunk = chunk->parent();
1911 assert(chunk != nullptr, "");
1912 assert(!chunk->is_empty(), "");
1913 jdk_internal_vm_Continuation::set_tail(continuation, chunk);
1914 }
1915
1916 // Verification
1917 chunk->verify();
1918 assert(chunk->max_thawing_size() > 0, "chunk invariant violated; expected to not be empty");
1919
1920 // Only make space for the last chunk because we only thaw from the last chunk
1921 int size = thaw_size(chunk) << LogBytesPerWord;
1922
1923 const address bottom = (address)thread->last_continuation()->entry_sp();
1924 // 300 is an estimate for stack size taken for this native code, in addition to StackShadowPages
1925 // for the Java frames in the check below.
1926 if (!stack_overflow_check(thread, size + 300, bottom)) {
1927 return 0;
1928 }
1929
1930 log_develop_trace(continuations)("prepare_thaw bottom: " INTPTR_FORMAT " top: " INTPTR_FORMAT " size: %d",
1931 p2i(bottom), p2i(bottom - size), size);
1932 return size;
1933 }
1934
1935 class ThawBase : public StackObj {
1936 protected:
1937 JavaThread* _thread;
1938 ContinuationWrapper& _cont;
1939 CONT_JFR_ONLY(FreezeThawJfrInfo _jfr_info;)
1940
1941 intptr_t* _fastpath;
1942 bool _barriers;
1943 bool _preempted_case;
1944 intptr_t* _top_unextended_sp_before_thaw;
1945 int _align_size;
1946 DEBUG_ONLY(intptr_t* _top_stack_address);
1947
1948 StackChunkFrameStream<ChunkFrames::Mixed> _stream;
1949
1950 NOT_PRODUCT(int _frames;)
1951
1952 protected:
1953 ThawBase(JavaThread* thread, ContinuationWrapper& cont) :
1954 _thread(thread), _cont(cont),
1955 _fastpath(nullptr) {
1956 DEBUG_ONLY(_top_unextended_sp_before_thaw = nullptr;)
1957 assert (cont.tail() != nullptr, "no last chunk");
1958 DEBUG_ONLY(_top_stack_address = _cont.entrySP() - thaw_size(cont.tail());)
1959 }
1960
1961 void clear_chunk(stackChunkOop chunk);
1962 template<bool check_stub>
1963 int remove_top_compiled_frame_from_chunk(stackChunkOop chunk, int &argsize);
1964 int remove_scalarized_frames(StackChunkFrameStream<ChunkFrames::CompiledOnly>& scfs, stackChunkOop chunk, int &argsize);
1965 void copy_from_chunk(intptr_t* from, intptr_t* to, int size);
1966
1967 void thaw_lockstack(stackChunkOop chunk);
1968
1969 // fast path
1970 inline void prefetch_chunk_pd(void* start, int size_words);
1971 void patch_return(intptr_t* sp, bool is_last);
1972
1973 intptr_t* handle_preempted_continuation(intptr_t* sp, Continuation::preempt_kind preempt_kind, bool fast_case);
1974 inline intptr_t* push_cleanup_continuation();
1975 void throw_interrupted_exception(JavaThread* current, frame& top);
1976
1977 void recurse_thaw(const frame& heap_frame, frame& caller, int num_frames, bool top_on_preempt_case);
1978 void finish_thaw(frame& f);
1979
1980 private:
1981 template<typename FKind> bool recurse_thaw_java_frame(frame& caller, int num_frames);
1982 void finalize_thaw(frame& entry, int argsize);
1983
1984 inline bool seen_by_gc();
1985
1986 inline void before_thaw_java_frame(const frame& hf, const frame& caller, bool bottom, int num_frame);
1987 inline void after_thaw_java_frame(const frame& f, bool bottom);
1988 inline void patch(frame& f, const frame& caller, bool bottom, bool augmented = false);
1989 void clear_bitmap_bits(address start, address end);
1990
1991 NOINLINE void recurse_thaw_interpreted_frame(const frame& hf, frame& caller, int num_frames);
1992 void recurse_thaw_compiled_frame(const frame& hf, frame& caller, int num_frames, bool stub_caller);
1993 void recurse_thaw_stub_frame(const frame& hf, frame& caller, int num_frames);
1994 void recurse_thaw_native_frame(const frame& hf, frame& caller, int num_frames);
1995
1996 void push_return_frame(frame& f);
1997 inline frame new_entry_frame();
1998 template<typename FKind> frame new_stack_frame(const frame& hf, frame& caller, bool bottom, int size_adjust = 0);
1999 inline void patch_pd(frame& f, const frame& sender);
2000 inline void patch_pd(frame& f, intptr_t* caller_sp);
2001 inline intptr_t* align(const frame& hf, intptr_t* frame_sp, frame& caller, bool bottom);
2002
2003 void maybe_set_fastpath(intptr_t* sp) { if (sp > _fastpath) _fastpath = sp; }
2004
2005 static inline void derelativize_interpreted_frame_metadata(const frame& hf, const frame& f);
2006
2007 public:
2008 CONT_JFR_ONLY(FreezeThawJfrInfo& jfr_info() { return _jfr_info; })
2009 };
2010
2011 template <typename ConfigT>
2012 class Thaw : public ThawBase {
2013 public:
2014 Thaw(JavaThread* thread, ContinuationWrapper& cont) : ThawBase(thread, cont) {}
2015
2016 inline bool can_thaw_fast(stackChunkOop chunk) {
2017 return !_barriers
2018 && _thread->cont_fastpath_thread_state()
2019 && !chunk->has_thaw_slowpath_condition()
2020 && !PreserveFramePointer;
2021 }
2022
2023 inline intptr_t* thaw(Continuation::thaw_kind kind);
2024 template<bool check_stub = false>
2025 NOINLINE intptr_t* thaw_fast(stackChunkOop chunk);
2026 NOINLINE intptr_t* thaw_slow(stackChunkOop chunk, Continuation::thaw_kind kind);
2027 inline void patch_caller_links(intptr_t* sp, intptr_t* bottom);
2028 };
2029
2030 template <typename ConfigT>
2031 inline intptr_t* Thaw<ConfigT>::thaw(Continuation::thaw_kind kind) {
2032 verify_continuation(_cont.continuation());
2033 assert(!jdk_internal_vm_Continuation::done(_cont.continuation()), "");
2034 assert(!_cont.is_empty(), "");
2035
2036 stackChunkOop chunk = _cont.tail();
2037 assert(chunk != nullptr, "guaranteed by prepare_thaw");
2038 assert(!chunk->is_empty(), "guaranteed by prepare_thaw");
2039
2040 _barriers = chunk->requires_barriers();
2041 return (LIKELY(can_thaw_fast(chunk))) ? thaw_fast(chunk)
2042 : thaw_slow(chunk, kind);
2043 }
2044
2045 class ReconstructedStack : public StackObj {
2046 intptr_t* _base; // _cont.entrySP(); // top of the entry frame
2047 int _thaw_size;
2048 int _argsize;
2049 public:
2050 ReconstructedStack(intptr_t* base, int thaw_size, int argsize)
2051 : _base(base), _thaw_size(thaw_size - (argsize == 0 ? frame::metadata_words_at_top : 0)), _argsize(argsize) {
2052 // The only possible source of misalignment is stack-passed arguments b/c compiled frames are 16-byte aligned.
2053 assert(argsize != 0 || (_base - _thaw_size) == ContinuationHelper::frame_align_pointer(_base - _thaw_size), "");
2054 // We're at most one alignment word away from entrySP
2055 assert(_base - 1 <= top() + total_size() + frame::metadata_words_at_bottom, "missed entry frame");
2056 }
2057
2058 int entry_frame_extension() const { return _argsize + (_argsize > 0 ? frame::metadata_words_at_top : 0); }
2059
2060 // top and bottom stack pointers
2061 intptr_t* sp() const { return ContinuationHelper::frame_align_pointer(_base - _thaw_size); }
2062 intptr_t* bottom_sp() const { return ContinuationHelper::frame_align_pointer(_base - entry_frame_extension()); }
2063
2064 // several operations operate on the totality of the stack being reconstructed,
2065 // including the metadata words
2066 intptr_t* top() const { return sp() - frame::metadata_words_at_bottom; }
2067 int total_size() const { return _thaw_size + frame::metadata_words_at_bottom; }
2068 };
2069
2070 inline void ThawBase::clear_chunk(stackChunkOop chunk) {
2071 chunk->set_sp(chunk->bottom());
2072 chunk->set_max_thawing_size(0);
2073 }
2074
2075 int ThawBase::remove_scalarized_frames(StackChunkFrameStream<ChunkFrames::CompiledOnly>& f, stackChunkOop chunk, int &argsize) {
2076 DEBUG_ONLY(intptr_t* const chunk_sp = chunk->start_address() + chunk->sp();)
2077 intptr_t* top = f.sp();
2078
2079 while (f.cb()->as_nmethod_or_null()->needs_stack_repair()) {
2080 f.next(SmallRegisterMap::instance(), false /* stop */);
2081 }
2082 assert(!f.is_done(), "");
2083 assert(f.is_compiled(), "");
2084
2085 intptr_t* bottom = f.sp() + f.cb()->frame_size();
2086 argsize = f.stack_argsize();
2087 int frames_size = bottom - top;
2088
2089 f.next(SmallRegisterMap::instance(), true /* stop */);
2090 bool empty = f.is_done();
2091 assert(!empty || argsize == chunk->argsize(), "");
2092
2093 if (empty) {
2094 clear_chunk(chunk);
2095 } else {
2096 chunk->set_sp(chunk->sp() + frames_size);
2097 chunk->set_max_thawing_size(chunk->max_thawing_size() - frames_size);
2098 // We set chunk->pc to the return pc into the next frame
2099 chunk->set_pc(f.pc());
2100 #ifdef ASSERT
2101 {
2102 intptr_t* retaddr_slot = (chunk_sp
2103 + frames_size
2104 - frame::sender_sp_ret_address_offset());
2105 assert(f.pc() == ContinuationHelper::return_address_at(retaddr_slot),
2106 "unexpected pc");
2107 }
2108 #endif
2109 }
2110 assert(empty == chunk->is_empty(), "");
2111 // returns the size required to store the frame on stack, and because it is a
2112 // compiled frame, it must include a copy of the arguments passed by the caller
2113 return frames_size + argsize + frame::metadata_words_at_top;
2114 }
2115
2116 template<bool check_stub>
2117 int ThawBase::remove_top_compiled_frame_from_chunk(stackChunkOop chunk, int &argsize) {
2118 bool empty = false;
2119 StackChunkFrameStream<ChunkFrames::CompiledOnly> f(chunk);
2120 DEBUG_ONLY(intptr_t* const chunk_sp = chunk->start_address() + chunk->sp();)
2121 assert(chunk_sp == f.sp(), "");
2122 assert(chunk_sp == f.unextended_sp(), "");
2123
2124 if (f.cb()->as_nmethod_or_null()->needs_stack_repair()) {
2125 return remove_scalarized_frames(f, chunk, argsize);
2126 }
2127
2128 int frame_size = f.cb()->frame_size();
2129 argsize = f.stack_argsize();
2130
2131 assert(!f.is_stub() || check_stub, "");
2132 if (check_stub && f.is_stub()) {
2133 // If we don't thaw the top compiled frame too, after restoring the saved
2134 // registers back in Java, we would hit the return barrier to thaw one more
2135 // frame effectively overwriting the restored registers during that call.
2136 f.next(SmallRegisterMap::instance(), true /* stop */);
2137 assert(!f.is_done(), "");
2138
2139 f.get_cb();
2140 assert(f.is_compiled(), "");
2141 frame_size += f.cb()->frame_size();
2142 argsize = f.stack_argsize();
2143
2144 if (f.cb()->as_nmethod()->is_marked_for_deoptimization()) {
2145 // The caller of the runtime stub when the continuation is preempted is not at a
2146 // Java call instruction, and so cannot rely on nmethod patching for deopt.
2147 log_develop_trace(continuations)("Deoptimizing runtime stub caller");
2148 f.to_frame().deoptimize(nullptr); // the null thread simply avoids the assertion in deoptimize which we're not set up for
2149 }
2150 }
2151
2152 f.next(SmallRegisterMap::instance(), true /* stop */);
2153 empty = f.is_done();
2154 assert(!empty || argsize == chunk->argsize(), "");
2155
2156 if (empty) {
2157 clear_chunk(chunk);
2158 } else {
2159 chunk->set_sp(chunk->sp() + frame_size);
2160 chunk->set_max_thawing_size(chunk->max_thawing_size() - frame_size);
2161 // We set chunk->pc to the return pc into the next frame
2162 chunk->set_pc(f.pc());
2163 #ifdef ASSERT
2164 {
2165 intptr_t* retaddr_slot = (chunk_sp
2166 + frame_size
2167 - frame::sender_sp_ret_address_offset());
2168 assert(f.pc() == ContinuationHelper::return_address_at(retaddr_slot),
2169 "unexpected pc");
2170 }
2171 #endif
2172 }
2173 assert(empty == chunk->is_empty(), "");
2174 // returns the size required to store the frame on stack, and because it is a
2175 // compiled frame, it must include a copy of the arguments passed by the caller
2176 return frame_size + argsize + frame::metadata_words_at_top;
2177 }
2178
2179 void ThawBase::thaw_lockstack(stackChunkOop chunk) {
2180 int lockStackSize = chunk->lockstack_size();
2181 assert(lockStackSize > 0 && lockStackSize <= LockStack::CAPACITY, "");
2182
2183 oop tmp_lockstack[LockStack::CAPACITY];
2184 chunk->transfer_lockstack(tmp_lockstack, _barriers);
2185 _thread->lock_stack().move_from_address(tmp_lockstack, lockStackSize);
2186
2187 chunk->set_lockstack_size(0);
2188 chunk->set_has_lockstack(false);
2189 }
2190
2191 void ThawBase::copy_from_chunk(intptr_t* from, intptr_t* to, int size) {
2192 assert(to >= _top_stack_address, "overwrote past thawing space"
2193 " to: " INTPTR_FORMAT " top_address: " INTPTR_FORMAT, p2i(to), p2i(_top_stack_address));
2194 assert(to + size <= _cont.entrySP(), "overwrote past thawing space");
2195 _cont.tail()->copy_from_chunk_to_stack(from, to, size);
2196 CONT_JFR_ONLY(_jfr_info.record_size_copied(size);)
2197 }
2198
2199 void ThawBase::patch_return(intptr_t* sp, bool is_last) {
2200 log_develop_trace(continuations)("thaw_fast patching -- sp: " INTPTR_FORMAT, p2i(sp));
2201
2202 address pc = !is_last ? StubRoutines::cont_returnBarrier() : _cont.entryPC();
2203 ContinuationHelper::patch_return_address_at(
2204 sp - frame::sender_sp_ret_address_offset(),
2205 pc);
2206 }
2207
2208 template <typename ConfigT>
2209 template<bool check_stub>
2210 NOINLINE intptr_t* Thaw<ConfigT>::thaw_fast(stackChunkOop chunk) {
2211 assert(chunk == _cont.tail(), "");
2212 assert(!chunk->has_mixed_frames(), "");
2213 assert(!chunk->requires_barriers(), "");
2214 assert(!chunk->has_bitmap(), "");
2215 assert(!_thread->is_interp_only_mode(), "");
2216
2217 LogTarget(Trace, continuations) lt;
2218 if (lt.develop_is_enabled()) {
2219 LogStream ls(lt);
2220 ls.print_cr("thaw_fast");
2221 chunk->print_on(true, &ls);
2222 }
2223
2224 // Below this heuristic, we thaw the whole chunk, above it we thaw just one frame.
2225 static const int threshold = 500; // words
2226
2227 const int full_chunk_size = chunk->stack_size() - chunk->sp(); // this initial size could be reduced if it's a partial thaw
2228 int argsize, thaw_size;
2229
2230 intptr_t* const chunk_sp = chunk->start_address() + chunk->sp();
2231
2232 bool partial, empty;
2233 if (LIKELY(!TEST_THAW_ONE_CHUNK_FRAME && (full_chunk_size < threshold))) {
2234 prefetch_chunk_pd(chunk->start_address(), full_chunk_size); // prefetch anticipating memcpy starting at highest address
2235
2236 partial = false;
2237 argsize = chunk->argsize(); // must be called *before* clearing the chunk
2238 clear_chunk(chunk);
2239 thaw_size = full_chunk_size;
2240 empty = true;
2241 } else { // thaw a single frame
2242 partial = true;
2243 thaw_size = remove_top_compiled_frame_from_chunk<check_stub>(chunk, argsize);
2244 empty = chunk->is_empty();
2245 }
2246
2247 // Are we thawing the last frame(s) in the continuation
2248 const bool is_last = empty && chunk->parent() == nullptr;
2249 assert(!is_last || argsize == 0, "");
2250
2251 log_develop_trace(continuations)("thaw_fast partial: %d is_last: %d empty: %d size: %d argsize: %d entrySP: " PTR_FORMAT,
2252 partial, is_last, empty, thaw_size, argsize, p2i(_cont.entrySP()));
2253
2254 ReconstructedStack rs(_cont.entrySP(), thaw_size, argsize);
2255
2256 // also copy metadata words at frame bottom
2257 copy_from_chunk(chunk_sp - frame::metadata_words_at_bottom, rs.top(), rs.total_size());
2258
2259 // update the ContinuationEntry
2260 _cont.set_argsize(argsize);
2261 log_develop_trace(continuations)("setting entry argsize: %d", _cont.argsize());
2262 assert(rs.bottom_sp() == _cont.entry()->bottom_sender_sp(), "");
2263
2264 // install the return barrier if not last frame, or the entry's pc if last
2265 patch_return(rs.bottom_sp(), is_last);
2266
2267 // insert the back links from callee to caller frames
2268 patch_caller_links(rs.top(), rs.top() + rs.total_size());
2269
2270 assert(is_last == _cont.is_empty(), "");
2271 assert(_cont.chunk_invariant(), "");
2272
2273 #if CONT_JFR
2274 EventContinuationThawFast e;
2275 if (e.should_commit()) {
2276 e.set_id(cast_from_oop<u8>(chunk));
2277 e.set_size(thaw_size << LogBytesPerWord);
2278 e.set_full(!partial);
2279 e.commit();
2280 }
2281 #endif
2282
2283 #ifdef ASSERT
2284 set_anchor(_thread, rs.sp());
2285 log_frames(_thread);
2286 if (LoomDeoptAfterThaw) {
2287 do_deopt_after_thaw(_thread);
2288 }
2289 clear_anchor(_thread);
2290 #endif
2291
2292 return rs.sp();
2293 }
2294
2295 inline bool ThawBase::seen_by_gc() {
2296 return _barriers || _cont.tail()->is_gc_mode();
2297 }
2298
2299 static inline void relativize_chunk_concurrently(stackChunkOop chunk) {
2300 #if INCLUDE_ZGC || INCLUDE_SHENANDOAHGC
2301 if (UseZGC || UseShenandoahGC) {
2302 chunk->relativize_derived_pointers_concurrently();
2303 }
2304 #endif
2305 }
2306
2307 template <typename ConfigT>
2308 NOINLINE intptr_t* Thaw<ConfigT>::thaw_slow(stackChunkOop chunk, Continuation::thaw_kind kind) {
2309 Continuation::preempt_kind preempt_kind;
2310 bool retry_fast_path = false;
2311
2312 _preempted_case = chunk->preempted();
2313 if (_preempted_case) {
2314 ObjectWaiter* waiter = java_lang_VirtualThread::objectWaiter(_thread->vthread());
2315 if (waiter != nullptr) {
2316 // Mounted again after preemption. Resume the pending monitor operation,
2317 // which will be either a monitorenter or Object.wait() call.
2318 ObjectMonitor* mon = waiter->monitor();
2319 preempt_kind = waiter->is_wait() ? Continuation::freeze_on_wait : Continuation::freeze_on_monitorenter;
2320
2321 bool mon_acquired = mon->resume_operation(_thread, waiter, _cont);
2322 assert(!mon_acquired || mon->has_owner(_thread), "invariant");
2323 if (!mon_acquired) {
2324 // Failed to acquire monitor. Return to enterSpecial to unmount again.
2325 return push_cleanup_continuation();
2326 }
2327 chunk = _cont.tail(); // reload oop in case of safepoint in resume_operation (if posting JVMTI events).
2328 } else {
2329 // Preemption cancelled in moniterenter case. We actually acquired
2330 // the monitor after freezing all frames so nothing to do.
2331 preempt_kind = Continuation::freeze_on_monitorenter;
2332 }
2333 // Call this first to avoid racing with GC threads later when modifying the chunk flags.
2334 relativize_chunk_concurrently(chunk);
2335 chunk->set_preempted(false);
2336 retry_fast_path = true;
2337 } else {
2338 relativize_chunk_concurrently(chunk);
2339 }
2340
2341 // On first thaw after freeze restore oops to the lockstack if any.
2342 assert(chunk->lockstack_size() == 0 || kind == Continuation::thaw_top, "");
2343 if (kind == Continuation::thaw_top && chunk->lockstack_size() > 0) {
2344 thaw_lockstack(chunk);
2345 retry_fast_path = true;
2346 }
2347
2348 // Retry the fast path now that we possibly cleared the FLAG_HAS_LOCKSTACK
2349 // and FLAG_PREEMPTED flags from the stackChunk.
2350 if (retry_fast_path && can_thaw_fast(chunk)) {
2351 intptr_t* sp = thaw_fast<true>(chunk);
2352 if (_preempted_case) {
2353 return handle_preempted_continuation(sp, preempt_kind, true /* fast_case */);
2354 }
2355 return sp;
2356 }
2357
2358 LogTarget(Trace, continuations) lt;
2359 if (lt.develop_is_enabled()) {
2360 LogStream ls(lt);
2361 ls.print_cr("thaw slow return_barrier: %d " INTPTR_FORMAT, kind, p2i(chunk));
2362 chunk->print_on(true, &ls);
2363 }
2364
2365 #if CONT_JFR
2366 EventContinuationThawSlow e;
2367 if (e.should_commit()) {
2368 e.set_id(cast_from_oop<u8>(_cont.continuation()));
2369 e.commit();
2370 }
2371 #endif
2372
2373 DEBUG_ONLY(_frames = 0;)
2374 _align_size = 0;
2375 int num_frames = kind == Continuation::thaw_top ? 2 : 1;
2376
2377 _stream = StackChunkFrameStream<ChunkFrames::Mixed>(chunk);
2378 _top_unextended_sp_before_thaw = _stream.unextended_sp();
2379
2380 frame heap_frame = _stream.to_frame();
2381 if (lt.develop_is_enabled()) {
2382 LogStream ls(lt);
2383 ls.print_cr("top hframe before (thaw):");
2384 assert(heap_frame.is_heap_frame(), "should have created a relative frame");
2385 heap_frame.print_value_on(&ls);
2386 }
2387
2388 frame caller; // the thawed caller on the stack
2389 recurse_thaw(heap_frame, caller, num_frames, _preempted_case);
2390 finish_thaw(caller); // caller is now the topmost thawed frame
2391 _cont.write();
2392
2393 assert(_cont.chunk_invariant(), "");
2394
2395 JVMTI_ONLY(invalidate_jvmti_stack(_thread));
2396
2397 _thread->set_cont_fastpath(_fastpath);
2398
2399 intptr_t* sp = caller.sp();
2400
2401 if (_preempted_case) {
2402 return handle_preempted_continuation(sp, preempt_kind, false /* fast_case */);
2403 }
2404 return sp;
2405 }
2406
2407 void ThawBase::recurse_thaw(const frame& heap_frame, frame& caller, int num_frames, bool top_on_preempt_case) {
2408 log_develop_debug(continuations)("thaw num_frames: %d", num_frames);
2409 assert(!_cont.is_empty(), "no more frames");
2410 assert(num_frames > 0, "");
2411 assert(!heap_frame.is_empty(), "");
2412
2413 if (top_on_preempt_case && (heap_frame.is_native_frame() || heap_frame.is_runtime_frame())) {
2414 heap_frame.is_native_frame() ? recurse_thaw_native_frame(heap_frame, caller, 2) : recurse_thaw_stub_frame(heap_frame, caller, 2);
2415 } else if (!heap_frame.is_interpreted_frame()) {
2416 recurse_thaw_compiled_frame(heap_frame, caller, num_frames, false);
2417 } else {
2418 recurse_thaw_interpreted_frame(heap_frame, caller, num_frames);
2419 }
2420 }
2421
2422 template<typename FKind>
2423 bool ThawBase::recurse_thaw_java_frame(frame& caller, int num_frames) {
2424 assert(num_frames > 0, "");
2425
2426 DEBUG_ONLY(_frames++;)
2427
2428 int argsize = _stream.stack_argsize();
2429 CodeBlob* cb = _stream.cb();
2430
2431 _stream.next(SmallRegisterMap::instance());
2432 assert(_stream.to_frame().is_empty() == _stream.is_done(), "");
2433
2434 // We never leave a compiled caller of an interpreted frame as the top frame in the chunk
2435 // as it makes detecting that situation and adjusting unextended_sp tricky. We also always
2436 // thaw the caller of a frame that needs_stack_repair, as it would otherwise complicate things:
2437 // - Regardless of whether the frame was extended or not, we would need to copy the right arg
2438 // size if its greater than the one given by the normal method signature (non-scalarized).
2439 // - If the frame was indeed extended, leaving its caller as the top frame would complicate walking
2440 // the chunk (we need unextended_sp, but we only have sp).
2441 if (num_frames == 1 && !_stream.is_done() && ((FKind::interpreted && _stream.is_compiled()) || (FKind::compiled && cb->as_nmethod_or_null()->needs_stack_repair()))) {
2442 log_develop_trace(continuations)("thawing extra compiled frame to not leave a compiled interpreted-caller at top");
2443 num_frames++;
2444 }
2445
2446 if (num_frames == 1 || _stream.is_done()) { // end recursion
2447 finalize_thaw(caller, FKind::interpreted ? 0 : argsize);
2448 return true; // bottom
2449 } else { // recurse
2450 recurse_thaw(_stream.to_frame(), caller, num_frames - 1, false /* top_on_preempt_case */);
2451 return false;
2452 }
2453 }
2454
2455 void ThawBase::finalize_thaw(frame& entry, int argsize) {
2456 stackChunkOop chunk = _cont.tail();
2457
2458 if (!_stream.is_done()) {
2459 assert(_stream.sp() >= chunk->sp_address(), "");
2460 chunk->set_sp(chunk->to_offset(_stream.sp()));
2461 chunk->set_pc(_stream.pc());
2462 } else {
2463 chunk->set_sp(chunk->bottom());
2464 chunk->set_pc(nullptr);
2465 }
2466 assert(_stream.is_done() == chunk->is_empty(), "");
2467
2468 int total_thawed = pointer_delta_as_int(_stream.unextended_sp(), _top_unextended_sp_before_thaw);
2469 chunk->set_max_thawing_size(chunk->max_thawing_size() - total_thawed);
2470
2471 _cont.set_argsize(argsize);
2472 entry = new_entry_frame();
2473
2474 assert(entry.sp() == _cont.entrySP(), "");
2475 assert(Continuation::is_continuation_enterSpecial(entry), "");
2476 assert(_cont.is_entry_frame(entry), "");
2477 }
2478
2479 inline void ThawBase::before_thaw_java_frame(const frame& hf, const frame& caller, bool bottom, int num_frame) {
2480 LogTarget(Trace, continuations) lt;
2481 if (lt.develop_is_enabled()) {
2482 LogStream ls(lt);
2483 ls.print_cr("======== THAWING FRAME: %d", num_frame);
2484 assert(hf.is_heap_frame(), "should be");
2485 hf.print_value_on(&ls);
2486 }
2487 assert(bottom == _cont.is_entry_frame(caller), "bottom: %d is_entry_frame: %d", bottom, _cont.is_entry_frame(hf));
2488 }
2489
2490 inline void ThawBase::after_thaw_java_frame(const frame& f, bool bottom) {
2491 #ifdef ASSERT
2492 LogTarget(Trace, continuations) lt;
2493 if (lt.develop_is_enabled()) {
2494 LogStream ls(lt);
2495 ls.print_cr("thawed frame:");
2496 print_frame_layout(f, false, &ls); // f.print_on(&ls);
2497 }
2498 #endif
2499 }
2500
2501 inline void ThawBase::patch(frame& f, const frame& caller, bool bottom, bool augmented) {
2502 assert(!bottom || caller.fp() == _cont.entryFP(), "");
2503 if (bottom) {
2504 ContinuationHelper::Frame::patch_pc(caller, _cont.is_empty() ? caller.pc()
2505 : StubRoutines::cont_returnBarrier());
2506 } else if (caller.is_compiled_frame()){
2507 // caller might have been deoptimized during thaw but we've overwritten the return address when copying f from the heap.
2508 // If the caller is not deoptimized, pc is unchanged.
2509 ContinuationHelper::Frame::patch_pc(caller, caller.raw_pc(), augmented /*callee_augmented*/);
2510 }
2511
2512 patch_pd(f, caller);
2513
2514 if (f.is_interpreted_frame()) {
2515 ContinuationHelper::InterpretedFrame::patch_sender_sp(f, caller);
2516 }
2517
2518 assert(!bottom || !_cont.is_empty() || Continuation::is_continuation_entry_frame(f, nullptr), "");
2519 assert(!bottom || (_cont.is_empty() != Continuation::is_cont_barrier_frame(f)), "");
2520 }
2521
2522 void ThawBase::clear_bitmap_bits(address start, address end) {
2523 assert(is_aligned(start, wordSize), "should be aligned: " PTR_FORMAT, p2i(start));
2524 assert(is_aligned(end, VMRegImpl::stack_slot_size), "should be aligned: " PTR_FORMAT, p2i(end));
2525
2526 // we need to clear the bits that correspond to arguments as they reside in the caller frame
2527 // or they will keep objects that are otherwise unreachable alive.
2528
2529 // Align `end` if UseCompressedOops is not set to avoid UB when calculating the bit index, since
2530 // `end` could be at an odd number of stack slots from `start`, i.e might not be oop aligned.
2531 // If that's the case the bit range corresponding to the last stack slot should not have bits set
2532 // anyways and we assert that before returning.
2533 address effective_end = UseCompressedOops ? end : align_down(end, wordSize);
2534 log_develop_trace(continuations)("clearing bitmap for " INTPTR_FORMAT " - " INTPTR_FORMAT, p2i(start), p2i(effective_end));
2535 stackChunkOop chunk = _cont.tail();
2536 chunk->bitmap().clear_range(chunk->bit_index_for(start), chunk->bit_index_for(effective_end));
2537 assert(effective_end == end || !chunk->bitmap().at(chunk->bit_index_for(effective_end)), "bit should not be set");
2538 }
2539
2540 intptr_t* ThawBase::handle_preempted_continuation(intptr_t* sp, Continuation::preempt_kind preempt_kind, bool fast_case) {
2541 assert(preempt_kind == Continuation::freeze_on_wait || preempt_kind == Continuation::freeze_on_monitorenter, "");
2542 frame top(sp);
2543 assert(top.pc() == *(address*)(sp - frame::sender_sp_ret_address_offset()), "");
2544
2545 #if INCLUDE_JVMTI
2546 // Finish the VTMS transition.
2547 assert(_thread->is_in_VTMS_transition(), "must be");
2548 bool is_vthread = Continuation::continuation_scope(_cont.continuation()) == java_lang_VirtualThread::vthread_scope();
2549 if (is_vthread) {
2550 if (JvmtiVTMSTransitionDisabler::VTMS_notify_jvmti_events()) {
2551 jvmti_mount_end(_thread, _cont, top);
2552 } else {
2553 _thread->set_is_in_VTMS_transition(false);
2554 java_lang_Thread::set_is_in_VTMS_transition(_thread->vthread(), false);
2555 }
2556 }
2557 #endif
2558
2559 if (fast_case) {
2560 // If we thawed in the slow path the runtime stub/native wrapper frame already
2561 // has the correct fp (see ThawBase::new_stack_frame). On the fast path though,
2562 // we copied the original fp at the time of freeze which now will have to be fixed.
2563 assert(top.is_runtime_frame() || top.is_native_frame(), "");
2564 int fsize = top.cb()->frame_size();
2565 patch_pd(top, sp + fsize);
2566 }
2567
2568 if (preempt_kind == Continuation::freeze_on_wait) {
2569 // Check now if we need to throw IE exception.
2570 if (_thread->pending_interrupted_exception()) {
2571 throw_interrupted_exception(_thread, top);
2572 _thread->set_pending_interrupted_exception(false);
2573 }
2574 } else if (top.is_runtime_frame()) {
2575 // The continuation might now run on a different platform thread than the previous time so
2576 // we need to adjust the current thread saved in the stub frame before restoring registers.
2577 JavaThread** thread_addr = frame::saved_thread_address(top);
2578 if (thread_addr != nullptr) *thread_addr = _thread;
2579 }
2580 return sp;
2581 }
2582
2583 void ThawBase::throw_interrupted_exception(JavaThread* current, frame& top) {
2584 ContinuationWrapper::SafepointOp so(current, _cont);
2585 // Since we might safepoint set the anchor so that the stack can be walked.
2586 set_anchor(current, top.sp());
2587 JRT_BLOCK
2588 THROW(vmSymbols::java_lang_InterruptedException());
2589 JRT_BLOCK_END
2590 clear_anchor(current);
2591 }
2592
2593 NOINLINE void ThawBase::recurse_thaw_interpreted_frame(const frame& hf, frame& caller, int num_frames) {
2594 assert(hf.is_interpreted_frame(), "");
2595
2596 if (UNLIKELY(seen_by_gc())) {
2597 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance());
2598 }
2599
2600 const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::InterpretedFrame>(caller, num_frames);
2601
2602 DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2603
2604 _align_size += frame::align_wiggle; // possible added alignment for internal interpreted frame alignment om AArch64
2605
2606 frame f = new_stack_frame<ContinuationHelper::InterpretedFrame>(hf, caller, is_bottom_frame);
2607
2608 intptr_t* const stack_frame_top = f.sp() + frame::metadata_words_at_top;
2609 intptr_t* const stack_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(f);
2610 intptr_t* const heap_frame_top = hf.unextended_sp() + frame::metadata_words_at_top;
2611 intptr_t* const heap_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(hf);
2612
2613 assert(hf.is_heap_frame(), "should be");
2614 assert(!f.is_heap_frame(), "should not be");
2615
2616 const int fsize = pointer_delta_as_int(heap_frame_bottom, heap_frame_top);
2617 assert((stack_frame_bottom == stack_frame_top + fsize), "");
2618
2619 // Some architectures (like AArch64/PPC64/RISC-V) add padding between the locals and the fixed_frame to keep the fp 16-byte-aligned.
2620 // On those architectures we freeze the padding in order to keep the same fp-relative offsets in the fixed_frame.
2621 copy_from_chunk(heap_frame_top, stack_frame_top, fsize);
2622
2623 // Make sure the relativized locals is already set.
2624 assert(f.interpreter_frame_local_at(0) == stack_frame_bottom - 1, "invalid frame bottom");
2625
2626 derelativize_interpreted_frame_metadata(hf, f);
2627 patch(f, caller, is_bottom_frame);
2628
2629 assert(f.is_interpreted_frame_valid(_cont.thread()), "invalid thawed frame");
2630 assert(stack_frame_bottom <= ContinuationHelper::Frame::frame_top(caller), "");
2631
2632 CONT_JFR_ONLY(_jfr_info.record_interpreted_frame();)
2633
2634 maybe_set_fastpath(f.sp());
2635
2636 Method* m = hf.interpreter_frame_method();
2637 assert(!m->is_native() || !is_bottom_frame, "should be top frame of thaw_top case; missing caller frame");
2638 const int locals = m->max_locals();
2639
2640 if (!is_bottom_frame) {
2641 // can only fix caller once this frame is thawed (due to callee saved regs)
2642 _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance());
2643 } else if (_cont.tail()->has_bitmap() && locals > 0) {
2644 assert(hf.is_heap_frame(), "should be");
2645 address start = (address)(heap_frame_bottom - locals);
2646 address end = (address)heap_frame_bottom;
2647 clear_bitmap_bits(start, end);
2648 }
2649
2650 DEBUG_ONLY(after_thaw_java_frame(f, is_bottom_frame);)
2651 caller = f;
2652 }
2653
2654 void ThawBase::recurse_thaw_compiled_frame(const frame& hf, frame& caller, int num_frames, bool stub_caller) {
2655 assert(hf.is_compiled_frame(), "");
2656 assert(_preempted_case || !stub_caller, "stub caller not at preemption");
2657
2658 if (!stub_caller && UNLIKELY(seen_by_gc())) { // recurse_thaw_stub_frame already invoked our barriers with a full regmap
2659 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance());
2660 }
2661
2662 const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::CompiledFrame>(caller, num_frames);
2663
2664 DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2665
2666 assert(caller.sp() == caller.unextended_sp(), "");
2667
2668 if ((!is_bottom_frame && caller.is_interpreted_frame()) || (is_bottom_frame && Interpreter::contains(_cont.tail()->pc()))) {
2669 _align_size += frame::align_wiggle; // we add one whether or not we've aligned because we add it in recurse_freeze_compiled_frame
2670 }
2671
2672 int fsize = 0;
2673 int added_argsize = 0;
2674 bool augmented = hf.was_augmented_on_entry(fsize);
2675 if (!augmented) {
2676 added_argsize = (is_bottom_frame || caller.is_interpreted_frame()) ? hf.compiled_frame_stack_argsize() : 0;
2677 fsize += added_argsize;
2678 }
2679 assert(!is_bottom_frame || !augmented, "");
2680
2681
2682 // new_stack_frame must construct the resulting frame using hf.pc() rather than hf.raw_pc() because the frame is not
2683 // yet laid out in the stack, and so the original_pc is not stored in it.
2684 // As a result, f.is_deoptimized_frame() is always false and we must test hf to know if the frame is deoptimized.
2685 frame f = new_stack_frame<ContinuationHelper::CompiledFrame>(hf, caller, is_bottom_frame, augmented ? fsize - hf.cb()->frame_size() : 0);
2686 assert(f.cb()->frame_size() == (int)(caller.sp() - f.sp()), "");
2687
2688 intptr_t* const stack_frame_top = f.sp();
2689 intptr_t* const heap_frame_top = hf.unextended_sp();
2690 intptr_t* from = heap_frame_top - frame::metadata_words_at_bottom;
2691 intptr_t* to = stack_frame_top - frame::metadata_words_at_bottom;
2692 // copy metadata, except the metadata at the top of the (unextended) entry frame
2693 int sz = fsize + frame::metadata_words_at_bottom + (is_bottom_frame && added_argsize == 0 ? 0 : frame::metadata_words_at_top);
2694
2695 // If we're the bottom-most thawed frame, we're writing to within one word from entrySP
2696 // (we might have one padding word for alignment)
2697 assert(!is_bottom_frame || (_cont.entrySP() - 1 <= to + sz && to + sz <= _cont.entrySP()), "");
2698 assert(!is_bottom_frame || hf.compiled_frame_stack_argsize() != 0 || (to + sz && to + sz == _cont.entrySP()), "");
2699
2700 copy_from_chunk(from, to, sz); // copying good oops because we invoked barriers above
2701
2702 patch(f, caller, is_bottom_frame, augmented);
2703
2704 // f.is_deoptimized_frame() is always false and we must test hf.is_deoptimized_frame() (see comment above)
2705 assert(!f.is_deoptimized_frame(), "");
2706 if (hf.is_deoptimized_frame()) {
2707 maybe_set_fastpath(f.sp());
2708 } else if (_thread->is_interp_only_mode()
2709 || (stub_caller && f.cb()->as_nmethod()->is_marked_for_deoptimization())) {
2710 // The caller of the safepoint stub when the continuation is preempted is not at a call instruction, and so
2711 // cannot rely on nmethod patching for deopt.
2712 assert(_thread->is_interp_only_mode() || stub_caller, "expected a stub-caller");
2713
2714 log_develop_trace(continuations)("Deoptimizing thawed frame");
2715 DEBUG_ONLY(ContinuationHelper::Frame::patch_pc(f, nullptr));
2716
2717 f.deoptimize(nullptr); // the null thread simply avoids the assertion in deoptimize which we're not set up for
2718 assert(f.is_deoptimized_frame(), "");
2719 assert(ContinuationHelper::Frame::is_deopt_return(f.raw_pc(), f), "");
2720 maybe_set_fastpath(f.sp());
2721 }
2722
2723 if (!is_bottom_frame) {
2724 // can only fix caller once this frame is thawed (due to callee saved regs); this happens on the stack
2725 _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance());
2726 } else if (_cont.tail()->has_bitmap() && added_argsize > 0) {
2727 address start = (address)(heap_frame_top + ContinuationHelper::CompiledFrame::size(hf) + frame::metadata_words_at_top);
2728 int stack_args_slots = f.cb()->as_nmethod()->num_stack_arg_slots(false /* rounded */);
2729 int argsize_in_bytes = stack_args_slots * VMRegImpl::stack_slot_size;
2730 clear_bitmap_bits(start, start + argsize_in_bytes);
2731 }
2732
2733 DEBUG_ONLY(after_thaw_java_frame(f, is_bottom_frame);)
2734 caller = f;
2735 }
2736
2737 void ThawBase::recurse_thaw_stub_frame(const frame& hf, frame& caller, int num_frames) {
2738 DEBUG_ONLY(_frames++;)
2739
2740 if (UNLIKELY(seen_by_gc())) {
2741 // Process the stub's caller here since we might need the full map.
2742 RegisterMap map(nullptr,
2743 RegisterMap::UpdateMap::include,
2744 RegisterMap::ProcessFrames::skip,
2745 RegisterMap::WalkContinuation::skip);
2746 map.set_include_argument_oops(false);
2747 _stream.next(&map);
2748 assert(!_stream.is_done(), "");
2749 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, &map);
2750 } else {
2751 _stream.next(SmallRegisterMap::instance());
2752 assert(!_stream.is_done(), "");
2753 }
2754
2755 recurse_thaw_compiled_frame(_stream.to_frame(), caller, num_frames, true);
2756
2757 assert(caller.is_compiled_frame(), "");
2758 assert(caller.sp() == caller.unextended_sp(), "");
2759
2760 DEBUG_ONLY(before_thaw_java_frame(hf, caller, false /*is_bottom_frame*/, num_frames);)
2761
2762 frame f = new_stack_frame<ContinuationHelper::StubFrame>(hf, caller, false);
2763 intptr_t* stack_frame_top = f.sp();
2764 intptr_t* heap_frame_top = hf.sp();
2765 int fsize = ContinuationHelper::StubFrame::size(hf);
2766
2767 copy_from_chunk(heap_frame_top - frame::metadata_words, stack_frame_top - frame::metadata_words,
2768 fsize + frame::metadata_words);
2769
2770 patch(f, caller, false /*is_bottom_frame*/);
2771
2772 // can only fix caller once this frame is thawed (due to callee saved regs)
2773 RegisterMap map(nullptr,
2774 RegisterMap::UpdateMap::include,
2775 RegisterMap::ProcessFrames::skip,
2776 RegisterMap::WalkContinuation::skip);
2777 map.set_include_argument_oops(false);
2778 f.oop_map()->update_register_map(&f, &map);
2779 ContinuationHelper::update_register_map_with_callee(caller, &map);
2780 _cont.tail()->fix_thawed_frame(caller, &map);
2781
2782 DEBUG_ONLY(after_thaw_java_frame(f, false /*is_bottom_frame*/);)
2783 caller = f;
2784 }
2785
2786 void ThawBase::recurse_thaw_native_frame(const frame& hf, frame& caller, int num_frames) {
2787 assert(hf.is_native_frame(), "");
2788 assert(_preempted_case && hf.cb()->as_nmethod()->method()->is_object_wait0(), "");
2789
2790 if (UNLIKELY(seen_by_gc())) { // recurse_thaw_stub_frame already invoked our barriers with a full regmap
2791 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance());
2792 }
2793
2794 const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::NativeFrame>(caller, num_frames);
2795 assert(!is_bottom_frame, "");
2796
2797 DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2798
2799 assert(caller.sp() == caller.unextended_sp(), "");
2800
2801 if (caller.is_interpreted_frame()) {
2802 _align_size += frame::align_wiggle; // we add one whether or not we've aligned because we add it in recurse_freeze_native_frame
2803 }
2804
2805 // new_stack_frame must construct the resulting frame using hf.pc() rather than hf.raw_pc() because the frame is not
2806 // yet laid out in the stack, and so the original_pc is not stored in it.
2807 // As a result, f.is_deoptimized_frame() is always false and we must test hf to know if the frame is deoptimized.
2808 frame f = new_stack_frame<ContinuationHelper::NativeFrame>(hf, caller, false /* bottom */);
2809 intptr_t* const stack_frame_top = f.sp();
2810 intptr_t* const heap_frame_top = hf.unextended_sp();
2811
2812 int fsize = ContinuationHelper::NativeFrame::size(hf);
2813 assert(fsize <= (int)(caller.unextended_sp() - f.unextended_sp()), "");
2814
2815 intptr_t* from = heap_frame_top - frame::metadata_words_at_bottom;
2816 intptr_t* to = stack_frame_top - frame::metadata_words_at_bottom;
2817 int sz = fsize + frame::metadata_words_at_bottom;
2818
2819 copy_from_chunk(from, to, sz); // copying good oops because we invoked barriers above
2820
2821 patch(f, caller, false /* bottom */);
2822
2823 // f.is_deoptimized_frame() is always false and we must test hf.is_deoptimized_frame() (see comment above)
2824 assert(!f.is_deoptimized_frame(), "");
2825 assert(!hf.is_deoptimized_frame(), "");
2826 assert(!f.cb()->as_nmethod()->is_marked_for_deoptimization(), "");
2827
2828 // can only fix caller once this frame is thawed (due to callee saved regs); this happens on the stack
2829 _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance());
2830
2831 DEBUG_ONLY(after_thaw_java_frame(f, false /* bottom */);)
2832 caller = f;
2833 }
2834
2835 void ThawBase::finish_thaw(frame& f) {
2836 stackChunkOop chunk = _cont.tail();
2837
2838 if (chunk->is_empty()) {
2839 // Only remove chunk from list if it can't be reused for another freeze
2840 if (seen_by_gc()) {
2841 _cont.set_tail(chunk->parent());
2842 } else {
2843 chunk->set_has_mixed_frames(false);
2844 }
2845 chunk->set_max_thawing_size(0);
2846 } else {
2847 chunk->set_max_thawing_size(chunk->max_thawing_size() - _align_size);
2848 }
2849 assert(chunk->is_empty() == (chunk->max_thawing_size() == 0), "");
2850
2851 if (!is_aligned(f.sp(), frame::frame_alignment)) {
2852 assert(f.is_interpreted_frame(), "");
2853 f.set_sp(align_down(f.sp(), frame::frame_alignment));
2854 }
2855 push_return_frame(f);
2856 chunk->fix_thawed_frame(f, SmallRegisterMap::instance()); // can only fix caller after push_return_frame (due to callee saved regs)
2857
2858 assert(_cont.is_empty() == _cont.last_frame().is_empty(), "");
2859
2860 log_develop_trace(continuations)("thawed %d frames", _frames);
2861
2862 LogTarget(Trace, continuations) lt;
2863 if (lt.develop_is_enabled()) {
2864 LogStream ls(lt);
2865 ls.print_cr("top hframe after (thaw):");
2866 _cont.last_frame().print_value_on(&ls);
2867 }
2868 }
2869
2870 void ThawBase::push_return_frame(frame& f) { // see generate_cont_thaw
2871 assert(!f.is_compiled_frame() || f.is_deoptimized_frame() == f.cb()->as_nmethod()->is_deopt_pc(f.raw_pc()), "");
2872 assert(!f.is_compiled_frame() || f.is_deoptimized_frame() == (f.pc() != f.raw_pc()), "");
2873
2874 LogTarget(Trace, continuations) lt;
2875 if (lt.develop_is_enabled()) {
2876 LogStream ls(lt);
2877 ls.print_cr("push_return_frame");
2878 f.print_value_on(&ls);
2879 }
2880
2881 assert(f.sp() - frame::metadata_words_at_bottom >= _top_stack_address, "overwrote past thawing space"
2882 " to: " INTPTR_FORMAT " top_address: " INTPTR_FORMAT, p2i(f.sp() - frame::metadata_words), p2i(_top_stack_address));
2883 ContinuationHelper::Frame::patch_pc(f, f.raw_pc()); // in case we want to deopt the frame in a full transition, this is checked.
2884 ContinuationHelper::push_pd(f);
2885
2886 assert(ContinuationHelper::Frame::assert_frame_laid_out(f), "");
2887 }
2888
2889 // returns new top sp
2890 // called after preparations (stack overflow check and making room)
2891 template<typename ConfigT>
2892 static inline intptr_t* thaw_internal(JavaThread* thread, const Continuation::thaw_kind kind) {
2893 assert(thread == JavaThread::current(), "Must be current thread");
2894
2895 CONT_JFR_ONLY(EventContinuationThaw event;)
2896
2897 log_develop_trace(continuations)("~~~~ thaw kind: %d sp: " INTPTR_FORMAT, kind, p2i(thread->last_continuation()->entry_sp()));
2898
2899 ContinuationEntry* entry = thread->last_continuation();
2900 assert(entry != nullptr, "");
2901 oop oopCont = entry->cont_oop(thread);
2902
2903 assert(!jdk_internal_vm_Continuation::done(oopCont), "");
2904 assert(oopCont == get_continuation(thread), "");
2905 verify_continuation(oopCont);
2906
2907 assert(entry->is_virtual_thread() == (entry->scope(thread) == java_lang_VirtualThread::vthread_scope()), "");
2908
2909 ContinuationWrapper cont(thread, oopCont);
2910 log_develop_debug(continuations)("THAW #" INTPTR_FORMAT " " INTPTR_FORMAT, cont.hash(), p2i((oopDesc*)oopCont));
2911
2912 #ifdef ASSERT
2913 set_anchor_to_entry(thread, cont.entry());
2914 log_frames(thread);
2915 clear_anchor(thread);
2916 #endif
2917
2918 DEBUG_ONLY(bool preempted = cont.tail()->preempted();)
2919 Thaw<ConfigT> thw(thread, cont);
2920 intptr_t* const sp = thw.thaw(kind);
2921 assert(is_aligned(sp, frame::frame_alignment), "");
2922 DEBUG_ONLY(log_frames_after_thaw(thread, cont, sp, preempted);)
2923
2924 CONT_JFR_ONLY(thw.jfr_info().post_jfr_event(&event, cont.continuation(), thread);)
2925
2926 verify_continuation(cont.continuation());
2927 log_develop_debug(continuations)("=== End of thaw #" INTPTR_FORMAT, cont.hash());
2928
2929 return sp;
2930 }
2931
2932 #ifdef ASSERT
2933 static void do_deopt_after_thaw(JavaThread* thread) {
2934 int i = 0;
2935 StackFrameStream fst(thread, true, false);
2936 fst.register_map()->set_include_argument_oops(false);
2937 ContinuationHelper::update_register_map_with_callee(*fst.current(), fst.register_map());
2938 for (; !fst.is_done(); fst.next()) {
2939 if (fst.current()->cb()->is_nmethod()) {
2940 nmethod* nm = fst.current()->cb()->as_nmethod();
2941 if (!nm->method()->is_continuation_native_intrinsic()) {
2942 nm->make_deoptimized();
2943 }
2944 }
2945 }
2946 }
2947
2948 class ThawVerifyOopsClosure: public OopClosure {
2949 intptr_t* _p;
2950 outputStream* _st;
2951 bool is_good_oop(oop o) {
2952 return dbg_is_safe(o, -1) && dbg_is_safe(o->klass(), -1) && oopDesc::is_oop(o) && o->klass()->is_klass();
2953 }
2954 public:
2955 ThawVerifyOopsClosure(outputStream* st) : _p(nullptr), _st(st) {}
2956 intptr_t* p() { return _p; }
2957 void reset() { _p = nullptr; }
2958
2959 virtual void do_oop(oop* p) {
2960 oop o = *p;
2961 if (o == nullptr || is_good_oop(o)) {
2962 return;
2963 }
2964 _p = (intptr_t*)p;
2965 _st->print_cr("*** non-oop " PTR_FORMAT " found at " PTR_FORMAT, p2i(*p), p2i(p));
2966 }
2967 virtual void do_oop(narrowOop* p) {
2968 oop o = RawAccess<>::oop_load(p);
2969 if (o == nullptr || is_good_oop(o)) {
2970 return;
2971 }
2972 _p = (intptr_t*)p;
2973 _st->print_cr("*** (narrow) non-oop %x found at " PTR_FORMAT, (int)(*p), p2i(p));
2974 }
2975 };
2976
2977 static bool do_verify_after_thaw(JavaThread* thread, stackChunkOop chunk, outputStream* st) {
2978 assert(thread->has_last_Java_frame(), "");
2979
2980 ResourceMark rm;
2981 ThawVerifyOopsClosure cl(st);
2982 NMethodToOopClosure cf(&cl, false);
2983
2984 StackFrameStream fst(thread, true, false);
2985 fst.register_map()->set_include_argument_oops(false);
2986 ContinuationHelper::update_register_map_with_callee(*fst.current(), fst.register_map());
2987 for (; !fst.is_done() && !Continuation::is_continuation_enterSpecial(*fst.current()); fst.next()) {
2988 if (fst.current()->cb()->is_nmethod() && fst.current()->cb()->as_nmethod()->is_marked_for_deoptimization()) {
2989 st->print_cr(">>> do_verify_after_thaw deopt");
2990 fst.current()->deoptimize(nullptr);
2991 fst.current()->print_on(st);
2992 }
2993
2994 fst.current()->oops_do(&cl, &cf, fst.register_map());
2995 if (cl.p() != nullptr) {
2996 frame fr = *fst.current();
2997 st->print_cr("Failed for frame barriers: %d",chunk->requires_barriers());
2998 fr.print_on(st);
2999 if (!fr.is_interpreted_frame()) {
3000 st->print_cr("size: %d argsize: %d",
3001 ContinuationHelper::NonInterpretedUnknownFrame::size(fr),
3002 ContinuationHelper::NonInterpretedUnknownFrame::stack_argsize(fr));
3003 }
3004 VMReg reg = fst.register_map()->find_register_spilled_here(cl.p(), fst.current()->sp());
3005 if (reg != nullptr) {
3006 st->print_cr("Reg %s %d", reg->name(), reg->is_stack() ? (int)reg->reg2stack() : -99);
3007 }
3008 cl.reset();
3009 DEBUG_ONLY(thread->print_frame_layout();)
3010 if (chunk != nullptr) {
3011 chunk->print_on(true, st);
3012 }
3013 return false;
3014 }
3015 }
3016 return true;
3017 }
3018
3019 static void log_frames(JavaThread* thread) {
3020 const static int show_entry_callers = 3;
3021 LogTarget(Trace, continuations) lt;
3022 if (!lt.develop_is_enabled()) {
3023 return;
3024 }
3025 LogStream ls(lt);
3026
3027 ls.print_cr("------- frames --------- for thread " INTPTR_FORMAT, p2i(thread));
3028 if (!thread->has_last_Java_frame()) {
3029 ls.print_cr("NO ANCHOR!");
3030 }
3031
3032 RegisterMap map(thread,
3033 RegisterMap::UpdateMap::include,
3034 RegisterMap::ProcessFrames::include,
3035 RegisterMap::WalkContinuation::skip);
3036 map.set_include_argument_oops(false);
3037
3038 if (false) {
3039 for (frame f = thread->last_frame(); !f.is_entry_frame(); f = f.sender(&map)) {
3040 f.print_on(&ls);
3041 }
3042 } else {
3043 map.set_skip_missing(true);
3044 ResetNoHandleMark rnhm;
3045 ResourceMark rm;
3046 HandleMark hm(Thread::current());
3047 FrameValues values;
3048
3049 int i = 0;
3050 int post_entry = -1;
3051 for (frame f = thread->last_frame(); !f.is_first_frame(); f = f.sender(&map), i++) {
3052 f.describe(values, i, &map, i == 0);
3053 if (post_entry >= 0 || Continuation::is_continuation_enterSpecial(f))
3054 post_entry++;
3055 if (post_entry >= show_entry_callers)
3056 break;
3057 }
3058 values.print_on(thread, &ls);
3059 }
3060
3061 ls.print_cr("======= end frames =========");
3062 }
3063
3064 static void log_frames_after_thaw(JavaThread* thread, ContinuationWrapper& cont, intptr_t* sp, bool preempted) {
3065 intptr_t* sp0 = sp;
3066 address pc0 = *(address*)(sp - frame::sender_sp_ret_address_offset());
3067
3068 if (preempted && sp0 == cont.entrySP()) {
3069 // Still preempted (monitor not acquired) so no frames were thawed.
3070 assert(cont.tail()->preempted(), "");
3071 set_anchor(thread, cont.entrySP(), cont.entryPC());
3072 } else {
3073 set_anchor(thread, sp0);
3074 }
3075
3076 log_frames(thread);
3077 if (LoomVerifyAfterThaw) {
3078 assert(do_verify_after_thaw(thread, cont.tail(), tty), "");
3079 }
3080 assert(ContinuationEntry::assert_entry_frame_laid_out(thread), "");
3081 clear_anchor(thread);
3082
3083 LogTarget(Trace, continuations) lt;
3084 if (lt.develop_is_enabled()) {
3085 LogStream ls(lt);
3086 ls.print_cr("Jumping to frame (thaw):");
3087 frame(sp).print_value_on(&ls);
3088 }
3089 }
3090 #endif // ASSERT
3091
3092 #include CPU_HEADER_INLINE(continuationFreezeThaw)
3093
3094 #ifdef ASSERT
3095 static void print_frame_layout(const frame& f, bool callee_complete, outputStream* st) {
3096 ResourceMark rm;
3097 FrameValues values;
3098 assert(f.get_cb() != nullptr, "");
3099 RegisterMap map(f.is_heap_frame() ?
3100 nullptr :
3101 JavaThread::current(),
3102 RegisterMap::UpdateMap::include,
3103 RegisterMap::ProcessFrames::skip,
3104 RegisterMap::WalkContinuation::skip);
3105 map.set_include_argument_oops(false);
3106 map.set_skip_missing(true);
3107 if (callee_complete) {
3108 frame::update_map_with_saved_link(&map, ContinuationHelper::Frame::callee_link_address(f));
3109 }
3110 const_cast<frame&>(f).describe(values, 0, &map, true);
3111 values.print_on(static_cast<JavaThread*>(nullptr), st);
3112 }
3113 #endif
3114
3115 static address thaw_entry = nullptr;
3116 static address freeze_entry = nullptr;
3117 static address freeze_preempt_entry = nullptr;
3118
3119 address Continuation::thaw_entry() {
3120 return ::thaw_entry;
3121 }
3122
3123 address Continuation::freeze_entry() {
3124 return ::freeze_entry;
3125 }
3126
3127 address Continuation::freeze_preempt_entry() {
3128 return ::freeze_preempt_entry;
3129 }
3130
3131 class ConfigResolve {
3132 public:
3133 static void resolve() { resolve_compressed(); }
3134
3135 static void resolve_compressed() {
3136 UseCompressedOops ? resolve_gc<true>()
3137 : resolve_gc<false>();
3138 }
3139
3140 private:
3141 template <bool use_compressed>
3142 static void resolve_gc() {
3143 BarrierSet* bs = BarrierSet::barrier_set();
3144 assert(bs != nullptr, "freeze/thaw invoked before BarrierSet is set");
3145 switch (bs->kind()) {
3146 #define BARRIER_SET_RESOLVE_BARRIER_CLOSURE(bs_name) \
3147 case BarrierSet::bs_name: { \
3148 resolve<use_compressed, typename BarrierSet::GetType<BarrierSet::bs_name>::type>(); \
3149 } \
3150 break;
3151 FOR_EACH_CONCRETE_BARRIER_SET_DO(BARRIER_SET_RESOLVE_BARRIER_CLOSURE)
3152 #undef BARRIER_SET_RESOLVE_BARRIER_CLOSURE
3153
3154 default:
3155 fatal("BarrierSet resolving not implemented");
3156 };
3157 }
3158
3159 template <bool use_compressed, typename BarrierSetT>
3160 static void resolve() {
3161 typedef Config<use_compressed ? oop_kind::NARROW : oop_kind::WIDE, BarrierSetT> SelectedConfigT;
3162
3163 freeze_entry = (address)freeze<SelectedConfigT>;
3164 freeze_preempt_entry = (address)SelectedConfigT::freeze_preempt;
3165
3166 // If we wanted, we could templatize by kind and have three different thaw entries
3167 thaw_entry = (address)thaw<SelectedConfigT>;
3168 }
3169 };
3170
3171 void Continuation::init() {
3172 ConfigResolve::resolve();
3173 }