1 /*
2 * Copyright (c) 2018, 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/javaClasses.inline.hpp"
27 #include "classfile/vmSymbols.hpp"
28 #include "code/codeCache.inline.hpp"
29 #include "code/nmethod.inline.hpp"
30 #include "code/vmreg.inline.hpp"
31 #include "compiler/oopMap.inline.hpp"
32 #include "gc/shared/continuationGCSupport.inline.hpp"
33 #include "gc/shared/gc_globals.hpp"
34 #include "gc/shared/barrierSet.hpp"
35 #include "gc/shared/memAllocator.hpp"
36 #include "gc/shared/threadLocalAllocBuffer.inline.hpp"
37 #include "interpreter/interpreter.hpp"
38 #include "jfr/jfrEvents.hpp"
39 #include "logging/log.hpp"
40 #include "logging/logStream.hpp"
41 #include "oops/access.inline.hpp"
42 #include "oops/method.inline.hpp"
43 #include "oops/oopsHierarchy.hpp"
44 #include "oops/objArrayOop.inline.hpp"
45 #include "oops/stackChunkOop.inline.hpp"
46 #include "prims/jvmtiThreadState.hpp"
47 #include "runtime/arguments.hpp"
48 #include "runtime/continuation.hpp"
49 #include "runtime/continuationEntry.inline.hpp"
50 #include "runtime/continuationHelper.inline.hpp"
51 #include "runtime/continuationJavaClasses.inline.hpp"
52 #include "runtime/continuationWrapper.inline.hpp"
53 #include "runtime/frame.inline.hpp"
54 #include "runtime/interfaceSupport.inline.hpp"
55 #include "runtime/javaThread.inline.hpp"
56 #include "runtime/jniHandles.inline.hpp"
57 #include "runtime/keepStackGCProcessed.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 #if INCLUDE_ZGC
70 #include "gc/z/zStackChunkGCData.inline.hpp"
71 #endif
72
73 #include <type_traits>
74
75 /*
76 * This file contains the implementation of continuation freezing (yield) and thawing (run).
77 *
78 * This code is very latency-critical and very hot. An ordinary and well-behaved server application
79 * would likely call these operations many thousands of times per second second, on every core.
80 *
81 * Freeze might be called every time the application performs any I/O operation, every time it
82 * acquires a j.u.c. lock, every time it takes a message from a queue, and thaw can be called
83 * multiple times in each of those cases, as it is called by the return barrier, which may be
84 * invoked on method return.
85 *
86 * The amortized budget for each of those two operations is ~100-150ns. That is why, for
87 * example, every effort is made to avoid Java-VM transitions as much as possible.
88 *
89 * On the fast path, all frames are known to be compiled, and the chunk requires no barriers
90 * and so frames simply copied, and the bottom-most one is patched.
91 * On the slow path, internal pointers in interpreted frames are de/relativized to/from offsets
92 * and absolute pointers, and barriers invoked.
93 */
94
95 /************************************************
96
97 Thread-stack layout on freeze/thaw.
98 See corresponding stack-chunk layout in instanceStackChunkKlass.hpp
99
100 +----------------------------+
101 | . |
102 | . |
103 | . |
104 | carrier frames |
105 | |
106 |----------------------------|
107 | |
108 | Continuation.run |
109 | |
110 |============================|
111 | enterSpecial frame |
112 | pc |
113 | rbp |
114 | ----- |
115 ^ | int argsize | = ContinuationEntry
116 | | oopDesc* cont |
117 | | oopDesc* chunk |
118 | | ContinuationEntry* parent |
119 | | ... |
120 | |============================| <------ JavaThread::_cont_entry = entry->sp()
121 | | ? alignment word ? |
122 | |----------------------------| <--\
123 | | | |
124 | | ? caller stack args ? | | argsize (might not be 2-word aligned) words
125 Address | | | | Caller is still in the chunk.
126 | |----------------------------| |
127 | | pc (? return barrier ?) | | This pc contains the return barrier when the bottom-most frame
128 | | rbp | | isn't the last one in the continuation.
129 | | | |
130 | | frame | |
131 | | | |
132 +----------------------------| \__ Continuation frames to be frozen/thawed
133 | | /
134 | frame | |
135 | | |
136 |----------------------------| |
137 | | |
138 | frame | |
139 | | |
140 |----------------------------| <--/
141 | |
142 | doYield/safepoint stub | When preempting forcefully, we could have a safepoint stub
143 | | instead of a doYield stub
144 |============================| <- the sp passed to freeze
145 | |
146 | Native freeze/thaw frames |
147 | . |
148 | . |
149 | . |
150 +----------------------------+
151
152 ************************************************/
153
154 static const bool TEST_THAW_ONE_CHUNK_FRAME = false; // force thawing frames one-at-a-time for testing
155
156 #define CONT_JFR false // emit low-level JFR events that count slow/fast path for continuation performance debugging only
157 #if CONT_JFR
158 #define CONT_JFR_ONLY(code) code
159 #else
160 #define CONT_JFR_ONLY(code)
161 #endif
162
163 // TODO: See AbstractAssembler::generate_stack_overflow_check,
164 // Compile::bang_size_in_bytes(), m->as_SafePoint()->jvms()->interpreter_frame_size()
165 // when we stack-bang, we need to update a thread field with the lowest (farthest) bang point.
166
167 // Data invariants are defined by Continuation::debug_verify_continuation and Continuation::debug_verify_stack_chunk
168
169 // Used to just annotatate cold/hot branches
170 #define LIKELY(condition) (condition)
171 #define UNLIKELY(condition) (condition)
172
173 // debugging functions
174 #ifdef ASSERT
175 extern "C" bool dbg_is_safe(const void* p, intptr_t errvalue); // address p is readable and *(intptr_t*)p != errvalue
176
177 static void verify_continuation(oop continuation) { Continuation::debug_verify_continuation(continuation); }
178
179 static void do_deopt_after_thaw(JavaThread* thread);
180 static bool do_verify_after_thaw(JavaThread* thread, stackChunkOop chunk, outputStream* st);
181 static void log_frames(JavaThread* thread);
182 static void print_frame_layout(const frame& f, bool callee_complete, outputStream* st = tty);
183
184 #define assert_pfl(p, ...) \
185 do { \
186 if (!(p)) { \
187 JavaThread* t = JavaThread::active(); \
188 if (t->has_last_Java_frame()) { \
189 tty->print_cr("assert(" #p ") failed:"); \
190 t->print_frame_layout(); \
191 } \
192 } \
193 vmassert(p, __VA_ARGS__); \
194 } while(0)
195
196 #else
197 static void verify_continuation(oop continuation) { }
198 #define assert_pfl(p, ...)
199 #endif
200
201 // should match Continuation.preemptStatus() in Continuation.java
202 enum freeze_result {
203 freeze_ok = 0,
204 freeze_ok_bottom = 1,
205 freeze_pinned_cs = 2,
206 freeze_pinned_native = 3,
207 freeze_pinned_monitor = 4,
208 freeze_exception = 5
209 };
210
211 const char* freeze_result_names[6] = {
212 "freeze_ok",
213 "freeze_ok_bottom",
214 "freeze_pinned_cs",
215 "freeze_pinned_native",
216 "freeze_pinned_monitor",
217 "freeze_exception"
218 };
219
220 static freeze_result is_pinned0(JavaThread* thread, oop cont_scope, bool safepoint);
221 template<typename ConfigT> static inline int freeze_internal(JavaThread* current, intptr_t* const sp);
222
223 static inline int prepare_thaw_internal(JavaThread* thread, bool return_barrier);
224 template<typename ConfigT> static inline intptr_t* thaw_internal(JavaThread* thread, const Continuation::thaw_kind kind);
225
226
227 // Entry point to freeze. Transitions are handled manually
228 // Called from gen_continuation_yield() in sharedRuntime_<cpu>.cpp through Continuation::freeze_entry();
229 template<typename ConfigT>
230 static JRT_BLOCK_ENTRY(int, freeze(JavaThread* current, intptr_t* sp))
231 assert(sp == current->frame_anchor()->last_Java_sp(), "");
232
233 if (current->raw_cont_fastpath() > current->last_continuation()->entry_sp() || current->raw_cont_fastpath() < sp) {
234 current->set_cont_fastpath(nullptr);
235 }
236
237 return ConfigT::freeze(current, sp);
238 JRT_END
239
240 JRT_LEAF(int, Continuation::prepare_thaw(JavaThread* thread, bool return_barrier))
241 return prepare_thaw_internal(thread, return_barrier);
242 JRT_END
243
244 template<typename ConfigT>
245 static JRT_LEAF(intptr_t*, thaw(JavaThread* thread, int kind))
246 // TODO: JRT_LEAF and NoHandleMark is problematic for JFR events.
247 // vFrameStreamCommon allocates Handles in RegisterMap for continuations.
248 // JRT_ENTRY instead?
249 ResetNoHandleMark rnhm;
250
251 // we might modify the code cache via BarrierSetNMethod::nmethod_entry_barrier
252 MACOS_AARCH64_ONLY(ThreadWXEnable __wx(WXWrite, thread));
253 return ConfigT::thaw(thread, (Continuation::thaw_kind)kind);
254 JRT_END
255
256 JVM_ENTRY(jint, CONT_isPinned0(JNIEnv* env, jobject cont_scope)) {
257 JavaThread* thread = JavaThread::thread_from_jni_environment(env);
258 return is_pinned0(thread, JNIHandles::resolve(cont_scope), false);
259 }
260 JVM_END
261
262 ///////////
263
264 enum class oop_kind { NARROW, WIDE };
265 template <oop_kind oops, typename BarrierSetT>
266 class Config {
267 public:
268 typedef Config<oops, BarrierSetT> SelfT;
269 using OopT = std::conditional_t<oops == oop_kind::NARROW, narrowOop, oop>;
270
271 static int freeze(JavaThread* thread, intptr_t* const sp) {
272 return freeze_internal<SelfT>(thread, sp);
273 }
274
275 static intptr_t* thaw(JavaThread* thread, Continuation::thaw_kind kind) {
276 return thaw_internal<SelfT>(thread, kind);
277 }
278 };
279
280 static bool stack_overflow_check(JavaThread* thread, size_t size, address sp) {
281 const size_t page_size = os::vm_page_size();
282 if (size > page_size) {
283 if (sp - size < thread->stack_overflow_state()->shadow_zone_safe_limit()) {
284 return false;
285 }
286 }
287 return true;
288 }
289
290 #ifdef ASSERT
291 static oop get_continuation(JavaThread* thread) {
292 assert(thread != nullptr, "");
293 assert(thread->threadObj() != nullptr, "");
294 return java_lang_Thread::continuation(thread->threadObj());
295 }
296
297 inline void clear_anchor(JavaThread* thread) {
298 thread->frame_anchor()->clear();
299 }
300
301 static void set_anchor(JavaThread* thread, intptr_t* sp) {
302 address pc = ContinuationHelper::return_address_at(
303 sp - frame::sender_sp_ret_address_offset());
304 assert(pc != nullptr, "");
305
306 JavaFrameAnchor* anchor = thread->frame_anchor();
307 anchor->set_last_Java_sp(sp);
308 anchor->set_last_Java_pc(pc);
309 ContinuationHelper::set_anchor_pd(anchor, sp);
310
311 assert(thread->has_last_Java_frame(), "");
312 assert(thread->last_frame().cb() != nullptr, "");
313 }
314 #endif // ASSERT
315
316 static void set_anchor_to_entry(JavaThread* thread, ContinuationEntry* entry) {
317 JavaFrameAnchor* anchor = thread->frame_anchor();
318 anchor->set_last_Java_sp(entry->entry_sp());
319 anchor->set_last_Java_pc(entry->entry_pc());
320 ContinuationHelper::set_anchor_to_entry_pd(anchor, entry);
321
322 assert(thread->has_last_Java_frame(), "");
323 assert(thread->last_frame().cb() != nullptr, "");
324 }
325
326 #if CONT_JFR
327 class FreezeThawJfrInfo : public StackObj {
328 short _e_size;
329 short _e_num_interpreted_frames;
330 public:
331
332 FreezeThawJfrInfo() : _e_size(0), _e_num_interpreted_frames(0) {}
333 inline void record_interpreted_frame() { _e_num_interpreted_frames++; }
334 inline void record_size_copied(int size) { _e_size += size << LogBytesPerWord; }
335 template<typename Event> void post_jfr_event(Event *e, oop continuation, JavaThread* jt);
336 };
337
338 template<typename Event> void FreezeThawJfrInfo::post_jfr_event(Event* e, oop continuation, JavaThread* jt) {
339 if (e->should_commit()) {
340 log_develop_trace(continuations)("JFR event: iframes: %d size: %d", _e_num_interpreted_frames, _e_size);
341 e->set_carrierThread(JFR_JVM_THREAD_ID(jt));
342 e->set_continuationClass(continuation->klass());
343 e->set_interpretedFrames(_e_num_interpreted_frames);
344 e->set_size(_e_size);
345 e->commit();
346 }
347 }
348 #endif // CONT_JFR
349
350 /////////////// FREEZE ////
351
352 class FreezeBase : public StackObj {
353 protected:
354 JavaThread* const _thread;
355 ContinuationWrapper& _cont;
356 bool _barriers; // only set when we allocate a chunk
357 const bool _preempt; // used only on the slow path
358 const intptr_t * const _frame_sp; // Top frame sp for this freeze
359
360 intptr_t* _bottom_address;
361
362 int _freeze_size; // total size of all frames plus metadata in words.
363 int _total_align_size;
364
365 intptr_t* _cont_stack_top;
366 intptr_t* _cont_stack_bottom;
367
368 CONT_JFR_ONLY(FreezeThawJfrInfo _jfr_info;)
369
370 #ifdef ASSERT
371 intptr_t* _orig_chunk_sp;
372 int _fast_freeze_size;
373 bool _empty;
374 #endif
375
376 JvmtiSampledObjectAllocEventCollector* _jvmti_event_collector;
377
378 NOT_PRODUCT(int _frames;)
379 DEBUG_ONLY(intptr_t* _last_write;)
380
381 inline FreezeBase(JavaThread* thread, ContinuationWrapper& cont, intptr_t* sp);
382
383 public:
384 NOINLINE freeze_result freeze_slow();
385 void freeze_fast_existing_chunk();
386
387 CONT_JFR_ONLY(FreezeThawJfrInfo& jfr_info() { return _jfr_info; })
388 void set_jvmti_event_collector(JvmtiSampledObjectAllocEventCollector* jsoaec) { _jvmti_event_collector = jsoaec; }
389
390 inline int size_if_fast_freeze_available();
391
392 #ifdef ASSERT
393 bool check_valid_fast_path();
394 #endif
395
396 protected:
397 inline void init_rest();
398 void throw_stack_overflow_on_humongous_chunk();
399
400 // fast path
401 inline void copy_to_chunk(intptr_t* from, intptr_t* to, int size);
402 inline void unwind_frames();
403 inline void patch_stack_pd(intptr_t* frame_sp, intptr_t* heap_sp);
404
405 // slow path
406 virtual stackChunkOop allocate_chunk_slow(size_t stack_size, int argsize_md) = 0;
407
408 int cont_size() { return pointer_delta_as_int(_cont_stack_bottom, _cont_stack_top); }
409
410 private:
411 // slow path
412 frame freeze_start_frame();
413 frame freeze_start_frame_safepoint_stub(frame f);
414 NOINLINE freeze_result recurse_freeze(frame& f, frame& caller, int callee_argsize, bool callee_interpreted, bool top);
415 inline frame freeze_start_frame_yield_stub(frame f);
416 template<typename FKind>
417 inline freeze_result recurse_freeze_java_frame(const frame& f, frame& caller, int fsize, int argsize);
418 inline void before_freeze_java_frame(const frame& f, const frame& caller, int fsize, int argsize, bool is_bottom_frame);
419 inline void after_freeze_java_frame(const frame& hf, bool is_bottom_frame);
420 freeze_result finalize_freeze(const frame& callee, frame& caller, int argsize);
421 void patch(const frame& f, frame& hf, const frame& caller, bool is_bottom_frame);
422 NOINLINE freeze_result recurse_freeze_interpreted_frame(frame& f, frame& caller, int callee_argsize, bool callee_interpreted);
423 freeze_result recurse_freeze_compiled_frame(frame& f, frame& caller, int callee_argsize, bool callee_interpreted);
424 NOINLINE freeze_result recurse_freeze_stub_frame(frame& f, frame& caller);
425 NOINLINE void finish_freeze(const frame& f, const frame& top);
426
427 inline bool stack_overflow();
428
429 static frame sender(const frame& f) { return f.is_interpreted_frame() ? sender<ContinuationHelper::InterpretedFrame>(f)
430 : sender<ContinuationHelper::NonInterpretedUnknownFrame>(f); }
431 template<typename FKind> static inline frame sender(const frame& f);
432 template<typename FKind> frame new_heap_frame(frame& f, frame& caller);
433 inline void set_top_frame_metadata_pd(const frame& hf);
434 inline void patch_pd(frame& callee, const frame& caller);
435 void adjust_interpreted_frame_unextended_sp(frame& f);
436 static inline void relativize_interpreted_frame_metadata(const frame& f, const frame& hf);
437
438 protected:
439 void freeze_fast_copy(stackChunkOop chunk, int chunk_start_sp CONT_JFR_ONLY(COMMA bool chunk_is_allocated));
440 bool freeze_fast_new_chunk(stackChunkOop chunk);
441 };
442
443 template <typename ConfigT>
444 class Freeze : public FreezeBase {
445 private:
446 stackChunkOop allocate_chunk(size_t stack_size, int argsize_md);
447
448 public:
449 inline Freeze(JavaThread* thread, ContinuationWrapper& cont, intptr_t* frame_sp)
450 : FreezeBase(thread, cont, frame_sp) {}
451
452 freeze_result try_freeze_fast();
453
454 protected:
455 virtual stackChunkOop allocate_chunk_slow(size_t stack_size, int argsize_md) override { return allocate_chunk(stack_size, argsize_md); }
456 };
457
458 FreezeBase::FreezeBase(JavaThread* thread, ContinuationWrapper& cont, intptr_t* frame_sp) :
459 _thread(thread), _cont(cont), _barriers(false), _preempt(false), _frame_sp(frame_sp) {
460 DEBUG_ONLY(_jvmti_event_collector = nullptr;)
461
462 assert(_thread != nullptr, "");
463 assert(_thread->last_continuation()->entry_sp() == _cont.entrySP(), "");
464
465 DEBUG_ONLY(_cont.entry()->verify_cookie();)
466
467 assert(!Interpreter::contains(_cont.entryPC()), "");
468
469 _bottom_address = _cont.entrySP() - _cont.entry_frame_extension();
470 #ifdef _LP64
471 if (((intptr_t)_bottom_address & 0xf) != 0) {
472 _bottom_address--;
473 }
474 assert(is_aligned(_bottom_address, frame::frame_alignment), "");
475 #endif
476
477 log_develop_trace(continuations)("bottom_address: " INTPTR_FORMAT " entrySP: " INTPTR_FORMAT " argsize: " PTR_FORMAT,
478 p2i(_bottom_address), p2i(_cont.entrySP()), (_cont.entrySP() - _bottom_address) << LogBytesPerWord);
479 assert(_bottom_address != nullptr, "");
480 assert(_bottom_address <= _cont.entrySP(), "");
481 DEBUG_ONLY(_last_write = nullptr;)
482
483 assert(_cont.chunk_invariant(), "");
484 assert(!Interpreter::contains(_cont.entryPC()), "");
485 #if !defined(PPC64) || defined(ZERO)
486 static const int doYield_stub_frame_size = frame::metadata_words;
487 #else
488 static const int doYield_stub_frame_size = frame::native_abi_reg_args_size >> LogBytesPerWord;
489 #endif
490 assert(SharedRuntime::cont_doYield_stub()->frame_size() == doYield_stub_frame_size, "");
491
492 // properties of the continuation on the stack; all sizes are in words
493 _cont_stack_top = frame_sp + doYield_stub_frame_size; // we don't freeze the doYield stub frame
494 _cont_stack_bottom = _cont.entrySP() + (_cont.argsize() == 0 ? frame::metadata_words_at_top : 0)
495 - ContinuationHelper::frame_align_words(_cont.argsize()); // see alignment in thaw
496
497 log_develop_trace(continuations)("freeze size: %d argsize: %d top: " INTPTR_FORMAT " bottom: " INTPTR_FORMAT,
498 cont_size(), _cont.argsize(), p2i(_cont_stack_top), p2i(_cont_stack_bottom));
499 assert(cont_size() > 0, "");
500 }
501
502 void FreezeBase::init_rest() { // we want to postpone some initialization after chunk handling
503 _freeze_size = 0;
504 _total_align_size = 0;
505 NOT_PRODUCT(_frames = 0;)
506 }
507
508 void FreezeBase::copy_to_chunk(intptr_t* from, intptr_t* to, int size) {
509 stackChunkOop chunk = _cont.tail();
510 chunk->copy_from_stack_to_chunk(from, to, size);
511 CONT_JFR_ONLY(_jfr_info.record_size_copied(size);)
512
513 #ifdef ASSERT
514 if (_last_write != nullptr) {
515 assert(_last_write == to + size, "Missed a spot: _last_write: " INTPTR_FORMAT " to+size: " INTPTR_FORMAT
516 " stack_size: %d _last_write offset: " PTR_FORMAT " to+size: " PTR_FORMAT, p2i(_last_write), p2i(to+size),
517 chunk->stack_size(), _last_write-chunk->start_address(), to+size-chunk->start_address());
518 _last_write = to;
519 }
520 #endif
521 }
522
523 // Called _after_ the last possible safepoint during the freeze operation (chunk allocation)
524 void FreezeBase::unwind_frames() {
525 ContinuationEntry* entry = _cont.entry();
526 entry->flush_stack_processing(_thread);
527 set_anchor_to_entry(_thread, entry);
528 }
529
530 template <typename ConfigT>
531 freeze_result Freeze<ConfigT>::try_freeze_fast() {
532 assert(_thread->thread_state() == _thread_in_vm, "");
533 assert(_thread->cont_fastpath(), "");
534
535 DEBUG_ONLY(_fast_freeze_size = size_if_fast_freeze_available();)
536 assert(_fast_freeze_size == 0, "");
537
538 stackChunkOop chunk = allocate_chunk(cont_size() + frame::metadata_words, _cont.argsize() + frame::metadata_words_at_top);
539 if (freeze_fast_new_chunk(chunk)) {
540 return freeze_ok;
541 }
542 if (_thread->has_pending_exception()) {
543 return freeze_exception;
544 }
545
546 // TODO R REMOVE when deopt change is fixed
547 assert(!_thread->cont_fastpath() || _barriers, "");
548 log_develop_trace(continuations)("-- RETRYING SLOW --");
549 return freeze_slow();
550 }
551
552 // Returns size needed if the continuation fits, otherwise 0.
553 int FreezeBase::size_if_fast_freeze_available() {
554 stackChunkOop chunk = _cont.tail();
555 if (chunk == nullptr || chunk->is_gc_mode() || chunk->requires_barriers() || chunk->has_mixed_frames()) {
556 log_develop_trace(continuations)("chunk available %s", chunk == nullptr ? "no chunk" : "chunk requires barriers");
557 return 0;
558 }
559
560 int total_size_needed = cont_size();
561 const int chunk_sp = chunk->sp();
562
563 // argsize can be nonzero if we have a caller, but the caller could be in a non-empty parent chunk,
564 // so we subtract it only if we overlap with the caller, i.e. the current chunk isn't empty.
565 // Consider leaving the chunk's argsize set when emptying it and removing the following branch,
566 // although that would require changing stackChunkOopDesc::is_empty
567 if (!chunk->is_empty()) {
568 total_size_needed -= _cont.argsize() + frame::metadata_words_at_top;
569 }
570
571 int chunk_free_room = chunk_sp - frame::metadata_words_at_bottom;
572 bool available = chunk_free_room >= total_size_needed;
573 log_develop_trace(continuations)("chunk available: %s size: %d argsize: %d top: " INTPTR_FORMAT " bottom: " INTPTR_FORMAT,
574 available ? "yes" : "no" , total_size_needed, _cont.argsize(), p2i(_cont_stack_top), p2i(_cont_stack_bottom));
575 return available ? total_size_needed : 0;
576 }
577
578 void FreezeBase::freeze_fast_existing_chunk() {
579 stackChunkOop chunk = _cont.tail();
580
581 DEBUG_ONLY(_fast_freeze_size = size_if_fast_freeze_available();)
582 assert(_fast_freeze_size > 0, "");
583
584 if (!chunk->is_empty()) { // we are copying into a non-empty chunk
585 DEBUG_ONLY(_empty = false;)
586 DEBUG_ONLY(_orig_chunk_sp = chunk->sp_address();)
587 #ifdef ASSERT
588 {
589 intptr_t* retaddr_slot = (chunk->sp_address()
590 - frame::sender_sp_ret_address_offset());
591 assert(ContinuationHelper::return_address_at(retaddr_slot) == chunk->pc(),
592 "unexpected saved return address");
593 }
594 #endif
595
596 // the chunk's sp before the freeze, adjusted to point beyond the stack-passed arguments in the topmost frame
597 // we overlap; we'll overwrite the chunk's top frame's callee arguments
598 const int chunk_start_sp = chunk->sp() + _cont.argsize() + frame::metadata_words_at_top;
599 assert(chunk_start_sp <= chunk->stack_size(), "sp not pointing into stack");
600
601 // increase max_size by what we're freezing minus the overlap
602 chunk->set_max_thawing_size(chunk->max_thawing_size() + cont_size() - _cont.argsize() - frame::metadata_words_at_top);
603
604 intptr_t* const bottom_sp = _cont_stack_bottom - _cont.argsize() - frame::metadata_words_at_top;
605 assert(bottom_sp == _bottom_address, "");
606 // Because the chunk isn't empty, we know there's a caller in the chunk, therefore the bottom-most frame
607 // should have a return barrier (installed back when we thawed it).
608 #ifdef ASSERT
609 {
610 intptr_t* retaddr_slot = (bottom_sp
611 - frame::sender_sp_ret_address_offset());
612 assert(ContinuationHelper::return_address_at(retaddr_slot)
613 == StubRoutines::cont_returnBarrier(),
614 "should be the continuation return barrier");
615 }
616 #endif
617 // We copy the fp from the chunk back to the stack because it contains some caller data,
618 // including, possibly, an oop that might have gone stale since we thawed.
619 patch_stack_pd(bottom_sp, chunk->sp_address());
620 // we don't patch the return pc at this time, so as not to make the stack unwalkable for async walks
621
622 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA false));
623 } else { // the chunk is empty
624 const int chunk_start_sp = chunk->stack_size();
625
626 DEBUG_ONLY(_empty = true;)
627 DEBUG_ONLY(_orig_chunk_sp = chunk->start_address() + chunk_start_sp;)
628
629 chunk->set_max_thawing_size(cont_size());
630 chunk->set_bottom(chunk_start_sp - _cont.argsize() - frame::metadata_words_at_top);
631 chunk->set_sp(chunk->bottom());
632
633 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA false));
634 }
635 }
636
637 bool FreezeBase::freeze_fast_new_chunk(stackChunkOop chunk) {
638 DEBUG_ONLY(_empty = true;)
639
640 // Install new chunk
641 _cont.set_tail(chunk);
642
643 if (UNLIKELY(chunk == nullptr || !_thread->cont_fastpath() || _barriers)) { // OOME/probably humongous
644 log_develop_trace(continuations)("Retrying slow. Barriers: %d", _barriers);
645 return false;
646 }
647
648 chunk->set_max_thawing_size(cont_size());
649
650 // in a fresh chunk, we freeze *with* the bottom-most frame's stack arguments.
651 // They'll then be stored twice: in the chunk and in the parent chunk's top frame
652 const int chunk_start_sp = cont_size() + frame::metadata_words;
653 assert(chunk_start_sp == chunk->stack_size(), "");
654
655 DEBUG_ONLY(_orig_chunk_sp = chunk->start_address() + chunk_start_sp;)
656
657 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA true));
658
659 return true;
660 }
661
662 void FreezeBase::freeze_fast_copy(stackChunkOop chunk, int chunk_start_sp CONT_JFR_ONLY(COMMA bool chunk_is_allocated)) {
663 assert(chunk != nullptr, "");
664 assert(!chunk->has_mixed_frames(), "");
665 assert(!chunk->is_gc_mode(), "");
666 assert(!chunk->has_bitmap(), "");
667 assert(!chunk->requires_barriers(), "");
668 assert(chunk == _cont.tail(), "");
669
670 // We unwind frames after the last safepoint so that the GC will have found the oops in the frames, but before
671 // writing into the chunk. This is so that an asynchronous stack walk (not at a safepoint) that suspends us here
672 // will either see no continuation on the stack, or a consistent chunk.
673 unwind_frames();
674
675 log_develop_trace(continuations)("freeze_fast start: chunk " INTPTR_FORMAT " size: %d orig sp: %d argsize: %d",
676 p2i((oopDesc*)chunk), chunk->stack_size(), chunk_start_sp, _cont.argsize());
677 assert(chunk_start_sp <= chunk->stack_size(), "");
678 assert(chunk_start_sp >= cont_size(), "no room in the chunk");
679
680 const int chunk_new_sp = chunk_start_sp - cont_size(); // the chunk's new sp, after freeze
681 assert(!(_fast_freeze_size > 0) || _orig_chunk_sp - (chunk->start_address() + chunk_new_sp) == _fast_freeze_size, "");
682
683 intptr_t* chunk_top = chunk->start_address() + chunk_new_sp;
684 #ifdef ASSERT
685 if (!_empty) {
686 intptr_t* retaddr_slot = (_orig_chunk_sp
687 - frame::sender_sp_ret_address_offset());
688 assert(ContinuationHelper::return_address_at(retaddr_slot) == chunk->pc(),
689 "unexpected saved return address");
690 }
691 #endif
692
693 log_develop_trace(continuations)("freeze_fast start: " INTPTR_FORMAT " sp: %d chunk_top: " INTPTR_FORMAT,
694 p2i(chunk->start_address()), chunk_new_sp, p2i(chunk_top));
695 intptr_t* from = _cont_stack_top - frame::metadata_words_at_bottom;
696 intptr_t* to = chunk_top - frame::metadata_words_at_bottom;
697 copy_to_chunk(from, to, cont_size() + frame::metadata_words_at_bottom);
698 // Because we're not patched yet, the chunk is now in a bad state
699
700 // patch return pc of the bottom-most frozen frame (now in the chunk)
701 // with the actual caller's return address
702 intptr_t* chunk_bottom_retaddr_slot = (chunk_top + cont_size()
703 - _cont.argsize()
704 - frame::metadata_words_at_top
705 - frame::sender_sp_ret_address_offset());
706 #ifdef ASSERT
707 if (!_empty) {
708 assert(ContinuationHelper::return_address_at(chunk_bottom_retaddr_slot)
709 == StubRoutines::cont_returnBarrier(),
710 "should be the continuation return barrier");
711 }
712 #endif
713 ContinuationHelper::patch_return_address_at(chunk_bottom_retaddr_slot,
714 chunk->pc());
715
716 // We're always writing to a young chunk, so the GC can't see it until the next safepoint.
717 chunk->set_sp(chunk_new_sp);
718 // set chunk->pc to the return address of the topmost frame in the chunk
719 chunk->set_pc(ContinuationHelper::return_address_at(
720 _cont_stack_top - frame::sender_sp_ret_address_offset()));
721
722 _cont.write();
723
724 log_develop_trace(continuations)("FREEZE CHUNK #" INTPTR_FORMAT " (young)", _cont.hash());
725 LogTarget(Trace, continuations) lt;
726 if (lt.develop_is_enabled()) {
727 LogStream ls(lt);
728 chunk->print_on(true, &ls);
729 }
730
731 // Verification
732 assert(_cont.chunk_invariant(), "");
733 chunk->verify();
734
735 #if CONT_JFR
736 EventContinuationFreezeFast e;
737 if (e.should_commit()) {
738 e.set_id(cast_from_oop<u8>(chunk));
739 DEBUG_ONLY(e.set_allocate(chunk_is_allocated);)
740 e.set_size(cont_size() << LogBytesPerWord);
741 e.commit();
742 }
743 #endif
744 }
745
746 NOINLINE freeze_result FreezeBase::freeze_slow() {
747 #ifdef ASSERT
748 ResourceMark rm;
749 #endif
750
751 log_develop_trace(continuations)("freeze_slow #" INTPTR_FORMAT, _cont.hash());
752 assert(_thread->thread_state() == _thread_in_vm || _thread->thread_state() == _thread_blocked, "");
753
754 #if CONT_JFR
755 EventContinuationFreezeSlow e;
756 if (e.should_commit()) {
757 e.set_id(cast_from_oop<u8>(_cont.continuation()));
758 e.commit();
759 }
760 #endif
761
762 init_rest();
763
764 HandleMark hm(Thread::current());
765
766 frame f = freeze_start_frame();
767
768 LogTarget(Debug, continuations) lt;
769 if (lt.develop_is_enabled()) {
770 LogStream ls(lt);
771 f.print_on(&ls);
772 }
773
774 frame caller; // the frozen caller in the chunk
775 freeze_result res = recurse_freeze(f, caller, 0, false, true);
776
777 if (res == freeze_ok) {
778 finish_freeze(f, caller);
779 _cont.write();
780 }
781
782 return res;
783 }
784
785 frame FreezeBase::freeze_start_frame() {
786 frame f = _thread->last_frame();
787 if (LIKELY(!_preempt)) {
788 return freeze_start_frame_yield_stub(f);
789 } else {
790 return freeze_start_frame_safepoint_stub(f);
791 }
792 }
793
794 frame FreezeBase::freeze_start_frame_yield_stub(frame f) {
795 assert(SharedRuntime::cont_doYield_stub()->contains(f.pc()), "must be");
796 f = sender<ContinuationHelper::NonInterpretedUnknownFrame>(f);
797 assert(Continuation::is_frame_in_continuation(_thread->last_continuation(), f), "");
798 return f;
799 }
800
801 frame FreezeBase::freeze_start_frame_safepoint_stub(frame f) {
802 #if (defined(X86) || defined(AARCH64) || defined(RISCV64)) && !defined(ZERO)
803 f.set_fp(f.real_fp()); // f.set_fp(*Frame::callee_link_address(f)); // ????
804 #else
805 Unimplemented();
806 #endif
807 if (!Interpreter::contains(f.pc())) {
808 assert(ContinuationHelper::Frame::is_stub(f.cb()), "must be");
809 assert(f.oop_map() != nullptr, "must be");
810
811 if (Interpreter::contains(ContinuationHelper::StubFrame::return_pc(f))) {
812 f = sender<ContinuationHelper::StubFrame>(f); // Safepoint stub in interpreter
813 }
814 }
815 assert(Continuation::is_frame_in_continuation(_thread->last_continuation(), f), "");
816 return f;
817 }
818
819 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
820 NOINLINE freeze_result FreezeBase::recurse_freeze(frame& f, frame& caller, int callee_argsize, bool callee_interpreted, bool top) {
821 assert(f.unextended_sp() < _bottom_address, ""); // see recurse_freeze_java_frame
822 assert(f.is_interpreted_frame() || ((top && _preempt) == ContinuationHelper::Frame::is_stub(f.cb())), "");
823
824 if (stack_overflow()) {
825 return freeze_exception;
826 }
827
828 if (f.is_compiled_frame()) {
829 if (UNLIKELY(f.oop_map() == nullptr)) {
830 // special native frame
831 return freeze_pinned_native;
832 }
833 return recurse_freeze_compiled_frame(f, caller, callee_argsize, callee_interpreted);
834 } else if (f.is_interpreted_frame()) {
835 assert((_preempt && top) || !f.interpreter_frame_method()->is_native(), "");
836 if (_preempt && top && f.interpreter_frame_method()->is_native()) {
837 // int native entry
838 return freeze_pinned_native;
839 }
840
841 return recurse_freeze_interpreted_frame(f, caller, callee_argsize, callee_interpreted);
842 } else if (_preempt && top && ContinuationHelper::Frame::is_stub(f.cb())) {
843 return recurse_freeze_stub_frame(f, caller);
844 } else {
845 return freeze_pinned_native;
846 }
847 }
848
849 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
850 // See also StackChunkFrameStream<frame_kind>::frame_size()
851 template<typename FKind>
852 inline freeze_result FreezeBase::recurse_freeze_java_frame(const frame& f, frame& caller, int fsize, int argsize) {
853 assert(FKind::is_instance(f), "");
854
855 assert(fsize > 0, "");
856 assert(argsize >= 0, "");
857 _freeze_size += fsize;
858 NOT_PRODUCT(_frames++;)
859
860 assert(FKind::frame_bottom(f) <= _bottom_address, "");
861
862 // We don't use FKind::frame_bottom(f) == _bottom_address because on x64 there's sometimes an extra word between
863 // enterSpecial and an interpreted frame
864 if (FKind::frame_bottom(f) >= _bottom_address - 1) {
865 return finalize_freeze(f, caller, argsize); // recursion end
866 } else {
867 frame senderf = sender<FKind>(f);
868 assert(FKind::interpreted || senderf.sp() == senderf.unextended_sp(), "");
869 freeze_result result = recurse_freeze(senderf, caller, argsize, FKind::interpreted, false); // recursive call
870 return result;
871 }
872 }
873
874 inline void FreezeBase::before_freeze_java_frame(const frame& f, const frame& caller, int fsize, int argsize, bool is_bottom_frame) {
875 LogTarget(Trace, continuations) lt;
876 if (lt.develop_is_enabled()) {
877 LogStream ls(lt);
878 ls.print_cr("======== FREEZING FRAME interpreted: %d bottom: %d", f.is_interpreted_frame(), is_bottom_frame);
879 ls.print_cr("fsize: %d argsize: %d", fsize, argsize);
880 f.print_value_on(&ls, nullptr);
881 }
882 assert(caller.is_interpreted_frame() == Interpreter::contains(caller.pc()), "");
883 }
884
885 inline void FreezeBase::after_freeze_java_frame(const frame& hf, bool is_bottom_frame) {
886 LogTarget(Trace, continuations) lt;
887 if (lt.develop_is_enabled()) {
888 LogStream ls(lt);
889 DEBUG_ONLY(hf.print_value_on(&ls, nullptr);)
890 assert(hf.is_heap_frame(), "should be");
891 DEBUG_ONLY(print_frame_layout(hf, false, &ls);)
892 if (is_bottom_frame) {
893 ls.print_cr("bottom h-frame:");
894 hf.print_on(&ls);
895 }
896 }
897 }
898
899 // The parameter argsize_md includes metadata that has to be part of caller/callee overlap.
900 // See also StackChunkFrameStream<frame_kind>::frame_size()
901 freeze_result FreezeBase::finalize_freeze(const frame& callee, frame& caller, int argsize_md) {
902 int argsize = argsize_md - frame::metadata_words_at_top;
903 assert(callee.is_interpreted_frame()
904 || callee.cb()->as_nmethod()->is_osr_method()
905 || argsize == _cont.argsize(), "argsize: %d cont.argsize: %d", argsize, _cont.argsize());
906 log_develop_trace(continuations)("bottom: " INTPTR_FORMAT " count %d size: %d argsize: %d",
907 p2i(_bottom_address), _frames, _freeze_size << LogBytesPerWord, argsize);
908
909 LogTarget(Trace, continuations) lt;
910
911 #ifdef ASSERT
912 bool empty = _cont.is_empty();
913 log_develop_trace(continuations)("empty: %d", empty);
914 #endif
915
916 stackChunkOop chunk = _cont.tail();
917
918 assert(chunk == nullptr || (chunk->max_thawing_size() == 0) == chunk->is_empty(), "");
919
920 _freeze_size += frame::metadata_words; // for top frame's metadata
921
922 int overlap = 0; // the args overlap the caller -- if there is one in this chunk and is of the same kind
923 int unextended_sp = -1;
924 if (chunk != nullptr) {
925 if (!chunk->is_empty()) {
926 StackChunkFrameStream<ChunkFrames::Mixed> last(chunk);
927 unextended_sp = chunk->to_offset(StackChunkFrameStream<ChunkFrames::Mixed>(chunk).unextended_sp());
928 bool top_interpreted = Interpreter::contains(chunk->pc());
929 if (callee.is_interpreted_frame() == top_interpreted) {
930 overlap = argsize_md;
931 }
932 } else {
933 unextended_sp = chunk->stack_size() - frame::metadata_words_at_top;
934 }
935 }
936
937 log_develop_trace(continuations)("finalize _size: %d overlap: %d unextended_sp: %d", _freeze_size, overlap, unextended_sp);
938
939 _freeze_size -= overlap;
940 assert(_freeze_size >= 0, "");
941
942 assert(chunk == nullptr || chunk->is_empty()
943 || unextended_sp == chunk->to_offset(StackChunkFrameStream<ChunkFrames::Mixed>(chunk).unextended_sp()), "");
944 assert(chunk != nullptr || unextended_sp < _freeze_size, "");
945
946 // _barriers can be set to true by an allocation in freeze_fast, in which case the chunk is available
947 bool allocated_old_in_freeze_fast = _barriers;
948 assert(!allocated_old_in_freeze_fast || (unextended_sp >= _freeze_size && chunk->is_empty()),
949 "Chunk allocated in freeze_fast is of insufficient size "
950 "unextended_sp: %d size: %d is_empty: %d", unextended_sp, _freeze_size, chunk->is_empty());
951 assert(!allocated_old_in_freeze_fast || (!UseZGC && !UseG1GC), "Unexpected allocation");
952
953 DEBUG_ONLY(bool empty_chunk = true);
954 if (unextended_sp < _freeze_size || chunk->is_gc_mode() || (!allocated_old_in_freeze_fast && chunk->requires_barriers())) {
955 // ALLOCATE NEW CHUNK
956
957 if (lt.develop_is_enabled()) {
958 LogStream ls(lt);
959 if (chunk == nullptr) {
960 ls.print_cr("no chunk");
961 } else {
962 ls.print_cr("chunk barriers: %d _size: %d free size: %d",
963 chunk->requires_barriers(), _freeze_size, chunk->sp() - frame::metadata_words);
964 chunk->print_on(&ls);
965 }
966 }
967
968 _freeze_size += overlap; // we're allocating a new chunk, so no overlap
969 // overlap = 0;
970
971 chunk = allocate_chunk_slow(_freeze_size, argsize_md);
972 if (chunk == nullptr) {
973 return freeze_exception;
974 }
975
976 // Install new chunk
977 _cont.set_tail(chunk);
978 assert(chunk->is_empty(), "");
979 } else {
980 // REUSE EXISTING CHUNK
981 log_develop_trace(continuations)("Reusing chunk mixed: %d empty: %d", chunk->has_mixed_frames(), chunk->is_empty());
982 if (chunk->is_empty()) {
983 int sp = chunk->stack_size() - argsize_md;
984 chunk->set_sp(sp);
985 chunk->set_bottom(sp);
986 _freeze_size += overlap;
987 assert(chunk->max_thawing_size() == 0, "");
988 } DEBUG_ONLY(else empty_chunk = false;)
989 }
990 assert(!chunk->is_gc_mode(), "");
991 assert(!chunk->has_bitmap(), "");
992 chunk->set_has_mixed_frames(true);
993
994 assert(chunk->requires_barriers() == _barriers, "");
995 assert(!_barriers || chunk->is_empty(), "");
996
997 assert(!chunk->is_empty() || StackChunkFrameStream<ChunkFrames::Mixed>(chunk).is_done(), "");
998 assert(!chunk->is_empty() || StackChunkFrameStream<ChunkFrames::Mixed>(chunk).to_frame().is_empty(), "");
999
1000 // We unwind frames after the last safepoint so that the GC will have found the oops in the frames, but before
1001 // writing into the chunk. This is so that an asynchronous stack walk (not at a safepoint) that suspends us here
1002 // will either see no continuation or a consistent chunk.
1003 unwind_frames();
1004
1005 chunk->set_max_thawing_size(chunk->max_thawing_size() + _freeze_size - frame::metadata_words);
1006
1007 if (lt.develop_is_enabled()) {
1008 LogStream ls(lt);
1009 ls.print_cr("top chunk:");
1010 chunk->print_on(&ls);
1011 }
1012
1013 // The topmost existing frame in the chunk; or an empty frame if the chunk is empty
1014 caller = StackChunkFrameStream<ChunkFrames::Mixed>(chunk).to_frame();
1015
1016 DEBUG_ONLY(_last_write = caller.unextended_sp() + (empty_chunk ? argsize_md : overlap);)
1017
1018 assert(chunk->is_in_chunk(_last_write - _freeze_size),
1019 "last_write-size: " INTPTR_FORMAT " start: " INTPTR_FORMAT, p2i(_last_write-_freeze_size), p2i(chunk->start_address()));
1020 #ifdef ASSERT
1021 if (lt.develop_is_enabled()) {
1022 LogStream ls(lt);
1023 ls.print_cr("top hframe before (freeze):");
1024 assert(caller.is_heap_frame(), "should be");
1025 caller.print_on(&ls);
1026 }
1027
1028 assert(!empty || Continuation::is_continuation_entry_frame(callee, nullptr), "");
1029
1030 frame entry = sender(callee);
1031
1032 assert(Continuation::is_return_barrier_entry(entry.pc()) || Continuation::is_continuation_enterSpecial(entry), "");
1033 assert(callee.is_interpreted_frame() || entry.sp() == entry.unextended_sp(), "");
1034 #endif
1035
1036 return freeze_ok_bottom;
1037 }
1038
1039 void FreezeBase::patch(const frame& f, frame& hf, const frame& caller, bool is_bottom_frame) {
1040 if (is_bottom_frame) {
1041 // If we're the bottom frame, we need to replace the return barrier with the real
1042 // caller's pc.
1043 address last_pc = caller.pc();
1044 assert((last_pc == nullptr) == _cont.tail()->is_empty(), "");
1045 ContinuationHelper::Frame::patch_pc(caller, last_pc);
1046 } else {
1047 assert(!caller.is_empty(), "");
1048 }
1049
1050 patch_pd(hf, caller);
1051
1052 if (f.is_interpreted_frame()) {
1053 assert(hf.is_heap_frame(), "should be");
1054 ContinuationHelper::InterpretedFrame::patch_sender_sp(hf, caller);
1055 }
1056
1057 #ifdef ASSERT
1058 if (hf.is_compiled_frame()) {
1059 if (f.is_deoptimized_frame()) { // TODO DEOPT: long term solution: unroll on freeze and patch pc
1060 log_develop_trace(continuations)("Freezing deoptimized frame");
1061 assert(f.cb()->as_nmethod()->is_deopt_pc(f.raw_pc()), "");
1062 assert(f.cb()->as_nmethod()->is_deopt_pc(ContinuationHelper::Frame::real_pc(f)), "");
1063 }
1064 }
1065 #endif
1066 }
1067
1068 #ifdef ASSERT
1069 static void verify_frame_top(const frame& f, intptr_t* top) {
1070 ResourceMark rm;
1071 InterpreterOopMap mask;
1072 f.interpreted_frame_oop_map(&mask);
1073 assert(top <= ContinuationHelper::InterpretedFrame::frame_top(f, &mask),
1074 "frame_top: " INTPTR_FORMAT " Interpreted::frame_top: " INTPTR_FORMAT,
1075 p2i(top), p2i(ContinuationHelper::InterpretedFrame::frame_top(f, &mask)));
1076 }
1077 #endif // ASSERT
1078
1079 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
1080 // See also StackChunkFrameStream<frame_kind>::frame_size()
1081 NOINLINE freeze_result FreezeBase::recurse_freeze_interpreted_frame(frame& f, frame& caller,
1082 int callee_argsize /* incl. metadata */,
1083 bool callee_interpreted) {
1084 adjust_interpreted_frame_unextended_sp(f);
1085
1086 // The frame's top never includes the stack arguments to the callee
1087 intptr_t* const stack_frame_top = ContinuationHelper::InterpretedFrame::frame_top(f, callee_argsize, callee_interpreted);
1088 intptr_t* const stack_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(f);
1089 const int fsize = pointer_delta_as_int(stack_frame_bottom, stack_frame_top);
1090
1091 DEBUG_ONLY(verify_frame_top(f, stack_frame_top));
1092
1093 Method* frame_method = ContinuationHelper::Frame::frame_method(f);
1094 // including metadata between f and its args
1095 const int argsize = ContinuationHelper::InterpretedFrame::stack_argsize(f) + frame::metadata_words_at_top;
1096
1097 log_develop_trace(continuations)("recurse_freeze_interpreted_frame %s _size: %d fsize: %d argsize: %d",
1098 frame_method->name_and_sig_as_C_string(), _freeze_size, fsize, argsize);
1099 // we'd rather not yield inside methods annotated with @JvmtiMountTransition
1100 assert(!ContinuationHelper::Frame::frame_method(f)->jvmti_mount_transition(), "");
1101
1102 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::InterpretedFrame>(f, caller, fsize, argsize);
1103 if (UNLIKELY(result > freeze_ok_bottom)) {
1104 return result;
1105 }
1106
1107 bool is_bottom_frame = result == freeze_ok_bottom;
1108 assert(!caller.is_empty() || is_bottom_frame, "");
1109
1110 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, 0, is_bottom_frame);)
1111
1112 frame hf = new_heap_frame<ContinuationHelper::InterpretedFrame>(f, caller);
1113 _total_align_size += frame::align_wiggle; // add alignment room for internal interpreted frame alignment on AArch64/PPC64
1114
1115 intptr_t* heap_frame_top = ContinuationHelper::InterpretedFrame::frame_top(hf, callee_argsize, callee_interpreted);
1116 intptr_t* heap_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(hf);
1117 assert(heap_frame_bottom == heap_frame_top + fsize, "");
1118
1119 // Some architectures (like AArch64/PPC64/RISC-V) add padding between the locals and the fixed_frame to keep the fp 16-byte-aligned.
1120 // On those architectures we freeze the padding in order to keep the same fp-relative offsets in the fixed_frame.
1121 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1122 assert(!is_bottom_frame || !caller.is_interpreted_frame() || (heap_frame_top + fsize) == (caller.unextended_sp() + argsize), "");
1123
1124 relativize_interpreted_frame_metadata(f, hf);
1125
1126 patch(f, hf, caller, is_bottom_frame);
1127
1128 CONT_JFR_ONLY(_jfr_info.record_interpreted_frame();)
1129 DEBUG_ONLY(after_freeze_java_frame(hf, is_bottom_frame);)
1130 caller = hf;
1131
1132 // Mark frame_method's GC epoch for class redefinition on_stack calculation.
1133 frame_method->record_gc_epoch();
1134
1135 return freeze_ok;
1136 }
1137
1138 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
1139 // See also StackChunkFrameStream<frame_kind>::frame_size()
1140 freeze_result FreezeBase::recurse_freeze_compiled_frame(frame& f, frame& caller,
1141 int callee_argsize /* incl. metadata */,
1142 bool callee_interpreted) {
1143 // The frame's top never includes the stack arguments to the callee
1144 intptr_t* const stack_frame_top = ContinuationHelper::CompiledFrame::frame_top(f, callee_argsize, callee_interpreted);
1145 intptr_t* const stack_frame_bottom = ContinuationHelper::CompiledFrame::frame_bottom(f);
1146 // including metadata between f and its stackargs
1147 const int argsize = ContinuationHelper::CompiledFrame::stack_argsize(f) + frame::metadata_words_at_top;
1148 const int fsize = pointer_delta_as_int(stack_frame_bottom + argsize, stack_frame_top);
1149
1150 log_develop_trace(continuations)("recurse_freeze_compiled_frame %s _size: %d fsize: %d argsize: %d",
1151 ContinuationHelper::Frame::frame_method(f) != nullptr ?
1152 ContinuationHelper::Frame::frame_method(f)->name_and_sig_as_C_string() : "",
1153 _freeze_size, fsize, argsize);
1154 // we'd rather not yield inside methods annotated with @JvmtiMountTransition
1155 assert(!ContinuationHelper::Frame::frame_method(f)->jvmti_mount_transition(), "");
1156
1157 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::CompiledFrame>(f, caller, fsize, argsize);
1158 if (UNLIKELY(result > freeze_ok_bottom)) {
1159 return result;
1160 }
1161
1162 bool is_bottom_frame = result == freeze_ok_bottom;
1163 assert(!caller.is_empty() || is_bottom_frame, "");
1164
1165 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, argsize, is_bottom_frame);)
1166
1167 frame hf = new_heap_frame<ContinuationHelper::CompiledFrame>(f, caller);
1168
1169 intptr_t* heap_frame_top = ContinuationHelper::CompiledFrame::frame_top(hf, callee_argsize, callee_interpreted);
1170
1171 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1172 assert(!is_bottom_frame || !caller.is_compiled_frame() || (heap_frame_top + fsize) == (caller.unextended_sp() + argsize), "");
1173
1174 if (caller.is_interpreted_frame()) {
1175 _total_align_size += frame::align_wiggle; // See Thaw::align
1176 }
1177
1178 patch(f, hf, caller, is_bottom_frame);
1179
1180 assert(is_bottom_frame || Interpreter::contains(ContinuationHelper::CompiledFrame::real_pc(caller)) == caller.is_interpreted_frame(), "");
1181
1182 DEBUG_ONLY(after_freeze_java_frame(hf, is_bottom_frame);)
1183 caller = hf;
1184 return freeze_ok;
1185 }
1186
1187 NOINLINE freeze_result FreezeBase::recurse_freeze_stub_frame(frame& f, frame& caller) {
1188 intptr_t* const stack_frame_top = ContinuationHelper::StubFrame::frame_top(f, 0, 0);
1189 const int fsize = f.cb()->frame_size();
1190
1191 log_develop_trace(continuations)("recurse_freeze_stub_frame %s _size: %d fsize: %d :: " INTPTR_FORMAT " - " INTPTR_FORMAT,
1192 f.cb()->name(), _freeze_size, fsize, p2i(stack_frame_top), p2i(stack_frame_top+fsize));
1193
1194 // recurse_freeze_java_frame and freeze inlined here because we need to use a full RegisterMap for lock ownership
1195 NOT_PRODUCT(_frames++;)
1196 _freeze_size += fsize;
1197
1198 RegisterMap map(_cont.thread(),
1199 RegisterMap::UpdateMap::include,
1200 RegisterMap::ProcessFrames::skip,
1201 RegisterMap::WalkContinuation::skip);
1202 map.set_include_argument_oops(false);
1203 ContinuationHelper::update_register_map<ContinuationHelper::StubFrame>(f, &map);
1204 f.oop_map()->update_register_map(&f, &map); // we have callee-save registers in this case
1205 frame senderf = sender<ContinuationHelper::StubFrame>(f);
1206 assert(senderf.unextended_sp() < _bottom_address - 1, "");
1207 assert(senderf.is_compiled_frame(), "");
1208
1209 if (UNLIKELY(senderf.oop_map() == nullptr)) {
1210 // native frame
1211 return freeze_pinned_native;
1212 }
1213
1214 freeze_result result = recurse_freeze_compiled_frame(senderf, caller, 0, 0); // This might be deoptimized
1215 if (UNLIKELY(result > freeze_ok_bottom)) {
1216 return result;
1217 }
1218 assert(result != freeze_ok_bottom, "");
1219 assert(!caller.is_interpreted_frame(), "");
1220
1221 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, 0, false);)
1222 frame hf = new_heap_frame<ContinuationHelper::StubFrame>(f, caller);
1223 intptr_t* heap_frame_top = ContinuationHelper::StubFrame::frame_top(hf, 0, 0);
1224 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1225 DEBUG_ONLY(after_freeze_java_frame(hf, false);)
1226
1227 caller = hf;
1228 return freeze_ok;
1229 }
1230
1231 NOINLINE void FreezeBase::finish_freeze(const frame& f, const frame& top) {
1232 stackChunkOop chunk = _cont.tail();
1233
1234 LogTarget(Trace, continuations) lt;
1235 if (lt.develop_is_enabled()) {
1236 LogStream ls(lt);
1237 assert(top.is_heap_frame(), "should be");
1238 top.print_on(&ls);
1239 }
1240
1241 set_top_frame_metadata_pd(top);
1242
1243 chunk->set_sp(chunk->to_offset(top.sp()));
1244 chunk->set_pc(top.pc());
1245
1246 chunk->set_max_thawing_size(chunk->max_thawing_size() + _total_align_size);
1247
1248 // At this point the chunk is consistent
1249
1250 if (UNLIKELY(_barriers)) {
1251 log_develop_trace(continuations)("do barriers on old chunk");
1252 // Serial and Parallel GC can allocate objects directly into the old generation.
1253 // Then we want to relativize the derived pointers eagerly so that
1254 // old chunks are all in GC mode.
1255 assert(!UseG1GC, "G1 can not deal with allocating outside of eden");
1256 assert(!UseZGC, "ZGC can not deal with allocating chunks visible to marking");
1257 if (UseShenandoahGC) {
1258 _cont.tail()->relativize_derived_pointers_concurrently();
1259 } else {
1260 ContinuationGCSupport::transform_stack_chunk(_cont.tail());
1261 }
1262 // For objects in the old generation we must maintain the remembered set
1263 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>();
1264 }
1265
1266 log_develop_trace(continuations)("finish_freeze: has_mixed_frames: %d", chunk->has_mixed_frames());
1267 if (lt.develop_is_enabled()) {
1268 LogStream ls(lt);
1269 chunk->print_on(true, &ls);
1270 }
1271
1272 if (lt.develop_is_enabled()) {
1273 LogStream ls(lt);
1274 ls.print_cr("top hframe after (freeze):");
1275 assert(_cont.last_frame().is_heap_frame(), "should be");
1276 _cont.last_frame().print_on(&ls);
1277 }
1278
1279 assert(_cont.chunk_invariant(), "");
1280 }
1281
1282 inline bool FreezeBase::stack_overflow() { // detect stack overflow in recursive native code
1283 JavaThread* t = !_preempt ? _thread : JavaThread::current();
1284 assert(t == JavaThread::current(), "");
1285 if (os::current_stack_pointer() < t->stack_overflow_state()->shadow_zone_safe_limit()) {
1286 if (!_preempt) {
1287 ContinuationWrapper::SafepointOp so(t, _cont); // could also call _cont.done() instead
1288 Exceptions::_throw_msg(t, __FILE__, __LINE__, vmSymbols::java_lang_StackOverflowError(), "Stack overflow while freezing");
1289 }
1290 return true;
1291 }
1292 return false;
1293 }
1294
1295 class StackChunkAllocator : public MemAllocator {
1296 const size_t _stack_size;
1297 int _argsize_md;
1298 ContinuationWrapper& _continuation_wrapper;
1299 JvmtiSampledObjectAllocEventCollector* const _jvmti_event_collector;
1300 mutable bool _took_slow_path;
1301
1302 // Does the minimal amount of initialization needed for a TLAB allocation.
1303 // We don't need to do a full initialization, as such an allocation need not be immediately walkable.
1304 virtual oop initialize(HeapWord* mem) const override {
1305 assert(_stack_size > 0, "");
1306 assert(_stack_size <= max_jint, "");
1307 assert(_word_size > _stack_size, "");
1308
1309 // zero out fields (but not the stack)
1310 const size_t hs = oopDesc::header_size();
1311 Copy::fill_to_aligned_words(mem + hs, vmClasses::StackChunk_klass()->size_helper() - hs);
1312
1313 int bottom = (int)_stack_size - _argsize_md;
1314
1315 jdk_internal_vm_StackChunk::set_size(mem, (int)_stack_size);
1316 jdk_internal_vm_StackChunk::set_bottom(mem, bottom);
1317 jdk_internal_vm_StackChunk::set_sp(mem, bottom);
1318
1319 return finish(mem);
1320 }
1321
1322 stackChunkOop allocate_fast() const {
1323 if (!UseTLAB) {
1324 return nullptr;
1325 }
1326
1327 HeapWord* const mem = MemAllocator::mem_allocate_inside_tlab_fast();
1328 if (mem == nullptr) {
1329 return nullptr;
1330 }
1331
1332 oop obj = initialize(mem);
1333 return stackChunkOopDesc::cast(obj);
1334 }
1335
1336 public:
1337 StackChunkAllocator(Klass* klass,
1338 size_t word_size,
1339 Thread* thread,
1340 size_t stack_size,
1341 int argsize_md,
1342 ContinuationWrapper& continuation_wrapper,
1343 JvmtiSampledObjectAllocEventCollector* jvmti_event_collector)
1344 : MemAllocator(klass, word_size, thread),
1345 _stack_size(stack_size),
1346 _argsize_md(argsize_md),
1347 _continuation_wrapper(continuation_wrapper),
1348 _jvmti_event_collector(jvmti_event_collector),
1349 _took_slow_path(false) {}
1350
1351 // Provides it's own, specialized allocation which skips instrumentation
1352 // if the memory can be allocated without going to a slow-path.
1353 stackChunkOop allocate() const {
1354 // First try to allocate without any slow-paths or instrumentation.
1355 stackChunkOop obj = allocate_fast();
1356 if (obj != nullptr) {
1357 return obj;
1358 }
1359
1360 // Now try full-blown allocation with all expensive operations,
1361 // including potentially safepoint operations.
1362 _took_slow_path = true;
1363
1364 // Protect unhandled Loom oops
1365 ContinuationWrapper::SafepointOp so(_thread, _continuation_wrapper);
1366
1367 // Can safepoint
1368 _jvmti_event_collector->start();
1369
1370 // Can safepoint
1371 return stackChunkOopDesc::cast(MemAllocator::allocate());
1372 }
1373
1374 bool took_slow_path() const {
1375 return _took_slow_path;
1376 }
1377 };
1378
1379 template <typename ConfigT>
1380 stackChunkOop Freeze<ConfigT>::allocate_chunk(size_t stack_size, int argsize_md) {
1381 log_develop_trace(continuations)("allocate_chunk allocating new chunk");
1382
1383 InstanceStackChunkKlass* klass = InstanceStackChunkKlass::cast(vmClasses::StackChunk_klass());
1384 size_t size_in_words = klass->instance_size(stack_size);
1385
1386 if (CollectedHeap::stack_chunk_max_size() > 0 && size_in_words >= CollectedHeap::stack_chunk_max_size()) {
1387 if (!_preempt) {
1388 throw_stack_overflow_on_humongous_chunk();
1389 }
1390 return nullptr;
1391 }
1392
1393 JavaThread* current = _preempt ? JavaThread::current() : _thread;
1394 assert(current == JavaThread::current(), "should be current");
1395
1396 // Allocate the chunk.
1397 //
1398 // This might safepoint while allocating, but all safepointing due to
1399 // instrumentation have been deferred. This property is important for
1400 // some GCs, as this ensures that the allocated object is in the young
1401 // generation / newly allocated memory.
1402 StackChunkAllocator allocator(klass, size_in_words, current, stack_size, argsize_md, _cont, _jvmti_event_collector);
1403 stackChunkOop chunk = allocator.allocate();
1404
1405 if (chunk == nullptr) {
1406 return nullptr; // OOME
1407 }
1408
1409 // assert that chunk is properly initialized
1410 assert(chunk->stack_size() == (int)stack_size, "");
1411 assert(chunk->size() >= stack_size, "chunk->size(): %zu size: %zu", chunk->size(), stack_size);
1412 assert(chunk->sp() == chunk->bottom(), "");
1413 assert((intptr_t)chunk->start_address() % 8 == 0, "");
1414 assert(chunk->max_thawing_size() == 0, "");
1415 assert(chunk->pc() == nullptr, "");
1416 assert(chunk->is_empty(), "");
1417 assert(chunk->flags() == 0, "");
1418 assert(chunk->is_gc_mode() == false, "");
1419
1420 // fields are uninitialized
1421 chunk->set_parent_access<IS_DEST_UNINITIALIZED>(_cont.last_nonempty_chunk());
1422 chunk->set_cont_access<IS_DEST_UNINITIALIZED>(_cont.continuation());
1423
1424 #if INCLUDE_ZGC
1425 if (UseZGC) {
1426 if (ZGenerational) {
1427 ZStackChunkGCData::initialize(chunk);
1428 }
1429 assert(!chunk->requires_barriers(), "ZGC always allocates in the young generation");
1430 _barriers = false;
1431 } else
1432 #endif
1433 #if INCLUDE_SHENANDOAHGC
1434 if (UseShenandoahGC) {
1435 _barriers = chunk->requires_barriers();
1436 } else
1437 #endif
1438 {
1439 if (!allocator.took_slow_path()) {
1440 // Guaranteed to be in young gen / newly allocated memory
1441 assert(!chunk->requires_barriers(), "Unfamiliar GC requires barriers on TLAB allocation");
1442 _barriers = false;
1443 } else {
1444 // Some GCs could put direct allocations in old gen for slow-path
1445 // allocations; need to explicitly check if that was the case.
1446 _barriers = chunk->requires_barriers();
1447 }
1448 }
1449
1450 if (_barriers) {
1451 log_develop_trace(continuations)("allocation requires barriers");
1452 }
1453
1454 assert(chunk->parent() == nullptr || chunk->parent()->is_stackChunk(), "");
1455
1456 return chunk;
1457 }
1458
1459 void FreezeBase::throw_stack_overflow_on_humongous_chunk() {
1460 ContinuationWrapper::SafepointOp so(_thread, _cont); // could also call _cont.done() instead
1461 Exceptions::_throw_msg(_thread, __FILE__, __LINE__, vmSymbols::java_lang_StackOverflowError(), "Humongous stack chunk");
1462 }
1463
1464 #if INCLUDE_JVMTI
1465 static int num_java_frames(ContinuationWrapper& cont) {
1466 ResourceMark rm; // used for scope traversal in num_java_frames(nmethod*, address)
1467 int count = 0;
1468 for (stackChunkOop chunk = cont.tail(); chunk != nullptr; chunk = chunk->parent()) {
1469 count += chunk->num_java_frames();
1470 }
1471 return count;
1472 }
1473
1474 static void invalidate_jvmti_stack(JavaThread* thread) {
1475 if (thread->is_interp_only_mode()) {
1476 JvmtiThreadState *state = thread->jvmti_thread_state();
1477 if (state != nullptr)
1478 state->invalidate_cur_stack_depth();
1479 }
1480 }
1481
1482 static void jvmti_yield_cleanup(JavaThread* thread, ContinuationWrapper& cont) {
1483 if (JvmtiExport::can_post_frame_pop()) {
1484 int num_frames = num_java_frames(cont);
1485
1486 ContinuationWrapper::SafepointOp so(Thread::current(), cont);
1487 JvmtiExport::continuation_yield_cleanup(JavaThread::current(), num_frames);
1488 }
1489 invalidate_jvmti_stack(thread);
1490 }
1491 #endif // INCLUDE_JVMTI
1492
1493 #ifdef ASSERT
1494 static bool monitors_on_stack(JavaThread* thread) {
1495 ContinuationEntry* ce = thread->last_continuation();
1496 RegisterMap map(thread,
1497 RegisterMap::UpdateMap::include,
1498 RegisterMap::ProcessFrames::include,
1499 RegisterMap::WalkContinuation::skip);
1500 map.set_include_argument_oops(false);
1501 for (frame f = thread->last_frame(); Continuation::is_frame_in_continuation(ce, f); f = f.sender(&map)) {
1502 if ((f.is_interpreted_frame() && ContinuationHelper::InterpretedFrame::is_owning_locks(f)) ||
1503 (f.is_compiled_frame() && ContinuationHelper::CompiledFrame::is_owning_locks(map.thread(), &map, f))) {
1504 return true;
1505 }
1506 }
1507 return false;
1508 }
1509
1510 // There are no interpreted frames if we're not called from the interpreter and we haven't ancountered an i2c
1511 // adapter or called Deoptimization::unpack_frames. As for native frames, upcalls from JNI also go through the
1512 // interpreter (see JavaCalls::call_helper), while the UpcallLinker explicitly sets cont_fastpath.
1513 bool FreezeBase::check_valid_fast_path() {
1514 ContinuationEntry* ce = _thread->last_continuation();
1515 RegisterMap map(_thread,
1516 RegisterMap::UpdateMap::skip,
1517 RegisterMap::ProcessFrames::skip,
1518 RegisterMap::WalkContinuation::skip);
1519 map.set_include_argument_oops(false);
1520 for (frame f = freeze_start_frame(); Continuation::is_frame_in_continuation(ce, f); f = f.sender(&map)) {
1521 if (!f.is_compiled_frame() || f.is_deoptimized_frame()) {
1522 return false;
1523 }
1524 }
1525 return true;
1526 }
1527 #endif // ASSERT
1528
1529 static inline int freeze_epilog(JavaThread* thread, ContinuationWrapper& cont) {
1530 verify_continuation(cont.continuation());
1531 assert(!cont.is_empty(), "");
1532 // This is done for the sake of the enterSpecial frame
1533 StackWatermarkSet::after_unwind(thread);
1534
1535 log_develop_debug(continuations)("=== End of freeze cont ### #" INTPTR_FORMAT, cont.hash());
1536
1537 return 0;
1538 }
1539
1540 static int freeze_epilog(JavaThread* thread, ContinuationWrapper& cont, freeze_result res) {
1541 if (UNLIKELY(res != freeze_ok)) {
1542 verify_continuation(cont.continuation());
1543 log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1544 return res;
1545 }
1546
1547 JVMTI_ONLY(jvmti_yield_cleanup(thread, cont)); // can safepoint
1548 return freeze_epilog(thread, cont);
1549 }
1550
1551 template<typename ConfigT>
1552 static inline int freeze_internal(JavaThread* current, intptr_t* const sp) {
1553 assert(!current->has_pending_exception(), "");
1554
1555 #ifdef ASSERT
1556 log_trace(continuations)("~~~~ freeze sp: " INTPTR_FORMAT, p2i(current->last_continuation()->entry_sp()));
1557 log_frames(current);
1558 #endif
1559
1560 CONT_JFR_ONLY(EventContinuationFreeze event;)
1561
1562 ContinuationEntry* entry = current->last_continuation();
1563
1564 oop oopCont = entry->cont_oop(current);
1565 assert(oopCont == current->last_continuation()->cont_oop(current), "");
1566 assert(ContinuationEntry::assert_entry_frame_laid_out(current), "");
1567
1568 verify_continuation(oopCont);
1569 ContinuationWrapper cont(current, oopCont);
1570 log_develop_debug(continuations)("FREEZE #" INTPTR_FORMAT " " INTPTR_FORMAT, cont.hash(), p2i((oopDesc*)oopCont));
1571
1572 assert(entry->is_virtual_thread() == (entry->scope(current) == java_lang_VirtualThread::vthread_scope()), "");
1573
1574 assert(monitors_on_stack(current) == ((current->held_monitor_count() - current->jni_monitor_count()) > 0),
1575 "Held monitor count and locks on stack invariant: " INT64_FORMAT " JNI: " INT64_FORMAT, (int64_t)current->held_monitor_count(), (int64_t)current->jni_monitor_count());
1576
1577 if (entry->is_pinned() || current->held_monitor_count() > 0) {
1578 log_develop_debug(continuations)("PINNED due to critical section/hold monitor");
1579 verify_continuation(cont.continuation());
1580 freeze_result res = entry->is_pinned() ? freeze_pinned_cs : freeze_pinned_monitor;
1581 log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1582 // Avoid Thread.yield() loops without safepoint polls.
1583 if (SafepointMechanism::should_process(current)) {
1584 cont.done(); // allow safepoint
1585 ThreadInVMfromJava tivmfj(current);
1586 }
1587 return res;
1588 }
1589
1590 Freeze<ConfigT> freeze(current, cont, sp);
1591
1592 assert(!current->cont_fastpath() || freeze.check_valid_fast_path(), "");
1593 bool fast = UseContinuationFastPath && current->cont_fastpath();
1594 if (fast && freeze.size_if_fast_freeze_available() > 0) {
1595 freeze.freeze_fast_existing_chunk();
1596 CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1597 freeze_epilog(current, cont);
1598 return 0;
1599 }
1600
1601 log_develop_trace(continuations)("chunk unavailable; transitioning to VM");
1602 assert(current == JavaThread::current(), "must be current thread except for preempt");
1603 JRT_BLOCK
1604 // delays a possible JvmtiSampledObjectAllocEventCollector in alloc_chunk
1605 JvmtiSampledObjectAllocEventCollector jsoaec(false);
1606 freeze.set_jvmti_event_collector(&jsoaec);
1607
1608 freeze_result res = fast ? freeze.try_freeze_fast() : freeze.freeze_slow();
1609
1610 CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1611 freeze_epilog(current, cont, res);
1612 cont.done(); // allow safepoint in the transition back to Java
1613 return res;
1614 JRT_BLOCK_END
1615 }
1616
1617 static freeze_result is_pinned0(JavaThread* thread, oop cont_scope, bool safepoint) {
1618 ContinuationEntry* entry = thread->last_continuation();
1619 if (entry == nullptr) {
1620 return freeze_ok;
1621 }
1622 if (entry->is_pinned()) {
1623 return freeze_pinned_cs;
1624 } else if (thread->held_monitor_count() > 0) {
1625 return freeze_pinned_monitor;
1626 }
1627
1628 RegisterMap map(thread,
1629 RegisterMap::UpdateMap::include,
1630 RegisterMap::ProcessFrames::skip,
1631 RegisterMap::WalkContinuation::skip);
1632 map.set_include_argument_oops(false);
1633 frame f = thread->last_frame();
1634
1635 if (!safepoint) {
1636 f = f.sender(&map); // this is the yield frame
1637 } else { // safepoint yield
1638 #if (defined(X86) || defined(AARCH64) || defined(RISCV64)) && !defined(ZERO)
1639 f.set_fp(f.real_fp()); // Instead of this, maybe in ContinuationWrapper::set_last_frame always use the real_fp?
1640 #else
1641 Unimplemented();
1642 #endif
1643 if (!Interpreter::contains(f.pc())) {
1644 assert(ContinuationHelper::Frame::is_stub(f.cb()), "must be");
1645 assert(f.oop_map() != nullptr, "must be");
1646 f.oop_map()->update_register_map(&f, &map); // we have callee-save registers in this case
1647 }
1648 }
1649
1650 while (true) {
1651 if ((f.is_interpreted_frame() && f.interpreter_frame_method()->is_native()) || f.is_native_frame()) {
1652 return freeze_pinned_native;
1653 }
1654
1655 f = f.sender(&map);
1656 if (!Continuation::is_frame_in_continuation(entry, f)) {
1657 oop scope = jdk_internal_vm_Continuation::scope(entry->cont_oop(thread));
1658 if (scope == cont_scope) {
1659 break;
1660 }
1661 intx monitor_count = entry->parent_held_monitor_count();
1662 entry = entry->parent();
1663 if (entry == nullptr) {
1664 break;
1665 }
1666 if (entry->is_pinned()) {
1667 return freeze_pinned_cs;
1668 } else if (monitor_count > 0) {
1669 return freeze_pinned_monitor;
1670 }
1671 }
1672 }
1673 return freeze_ok;
1674 }
1675
1676 /////////////// THAW ////
1677
1678 static int thaw_size(stackChunkOop chunk) {
1679 int size = chunk->max_thawing_size();
1680 size += frame::metadata_words; // For the top pc+fp in push_return_frame or top = stack_sp - frame::metadata_words in thaw_fast
1681 size += 2*frame::align_wiggle; // in case of alignments at the top and bottom
1682 return size;
1683 }
1684
1685 // make room on the stack for thaw
1686 // returns the size in bytes, or 0 on failure
1687 static inline int prepare_thaw_internal(JavaThread* thread, bool return_barrier) {
1688 log_develop_trace(continuations)("~~~~ prepare_thaw return_barrier: %d", return_barrier);
1689
1690 assert(thread == JavaThread::current(), "");
1691
1692 ContinuationEntry* ce = thread->last_continuation();
1693 assert(ce != nullptr, "");
1694 oop continuation = ce->cont_oop(thread);
1695 assert(continuation == get_continuation(thread), "");
1696 verify_continuation(continuation);
1697
1698 stackChunkOop chunk = jdk_internal_vm_Continuation::tail(continuation);
1699 assert(chunk != nullptr, "");
1700
1701 // The tail can be empty because it might still be available for another freeze.
1702 // However, here we want to thaw, so we get rid of it (it will be GCed).
1703 if (UNLIKELY(chunk->is_empty())) {
1704 chunk = chunk->parent();
1705 assert(chunk != nullptr, "");
1706 assert(!chunk->is_empty(), "");
1707 jdk_internal_vm_Continuation::set_tail(continuation, chunk);
1708 }
1709
1710 // Verification
1711 chunk->verify();
1712 assert(chunk->max_thawing_size() > 0, "chunk invariant violated; expected to not be empty");
1713
1714 // Only make space for the last chunk because we only thaw from the last chunk
1715 int size = thaw_size(chunk) << LogBytesPerWord;
1716
1717 const address bottom = (address)thread->last_continuation()->entry_sp();
1718 // 300 is an estimate for stack size taken for this native code, in addition to StackShadowPages
1719 // for the Java frames in the check below.
1720 if (!stack_overflow_check(thread, size + 300, bottom)) {
1721 return 0;
1722 }
1723
1724 log_develop_trace(continuations)("prepare_thaw bottom: " INTPTR_FORMAT " top: " INTPTR_FORMAT " size: %d",
1725 p2i(bottom), p2i(bottom - size), size);
1726 return size;
1727 }
1728
1729 class ThawBase : public StackObj {
1730 protected:
1731 JavaThread* _thread;
1732 ContinuationWrapper& _cont;
1733 CONT_JFR_ONLY(FreezeThawJfrInfo _jfr_info;)
1734
1735 intptr_t* _fastpath;
1736 bool _barriers;
1737 intptr_t* _top_unextended_sp_before_thaw;
1738 int _align_size;
1739 DEBUG_ONLY(intptr_t* _top_stack_address);
1740
1741 StackChunkFrameStream<ChunkFrames::Mixed> _stream;
1742
1743 NOT_PRODUCT(int _frames;)
1744
1745 protected:
1746 ThawBase(JavaThread* thread, ContinuationWrapper& cont) :
1747 _thread(thread), _cont(cont),
1748 _fastpath(nullptr) {
1749 DEBUG_ONLY(_top_unextended_sp_before_thaw = nullptr;)
1750 assert (cont.tail() != nullptr, "no last chunk");
1751 DEBUG_ONLY(_top_stack_address = _cont.entrySP() - thaw_size(cont.tail());)
1752 }
1753
1754 void clear_chunk(stackChunkOop chunk);
1755 int remove_top_compiled_frame_from_chunk(stackChunkOop chunk, int &argsize);
1756 void copy_from_chunk(intptr_t* from, intptr_t* to, int size);
1757
1758 // fast path
1759 inline void prefetch_chunk_pd(void* start, int size_words);
1760 void patch_return(intptr_t* sp, bool is_last);
1761
1762 // slow path
1763 NOINLINE intptr_t* thaw_slow(stackChunkOop chunk, bool return_barrier);
1764
1765 private:
1766 void recurse_thaw(const frame& heap_frame, frame& caller, int num_frames, bool top);
1767 template<typename FKind> bool recurse_thaw_java_frame(frame& caller, int num_frames);
1768 void finalize_thaw(frame& entry, int argsize);
1769
1770 inline bool seen_by_gc();
1771
1772 inline void before_thaw_java_frame(const frame& hf, const frame& caller, bool bottom, int num_frame);
1773 inline void after_thaw_java_frame(const frame& f, bool bottom);
1774 inline void patch(frame& f, const frame& caller, bool bottom);
1775 void clear_bitmap_bits(address start, address end);
1776
1777 NOINLINE void recurse_thaw_interpreted_frame(const frame& hf, frame& caller, int num_frames);
1778 void recurse_thaw_compiled_frame(const frame& hf, frame& caller, int num_frames, bool stub_caller);
1779 void recurse_thaw_stub_frame(const frame& hf, frame& caller, int num_frames);
1780 void finish_thaw(frame& f);
1781
1782 void push_return_frame(frame& f);
1783 inline frame new_entry_frame();
1784 template<typename FKind> frame new_stack_frame(const frame& hf, frame& caller, bool bottom);
1785 inline void patch_pd(frame& f, const frame& sender);
1786 inline intptr_t* align(const frame& hf, intptr_t* frame_sp, frame& caller, bool bottom);
1787
1788 void maybe_set_fastpath(intptr_t* sp) { if (sp > _fastpath) _fastpath = sp; }
1789
1790 static inline void derelativize_interpreted_frame_metadata(const frame& hf, const frame& f);
1791
1792 public:
1793 CONT_JFR_ONLY(FreezeThawJfrInfo& jfr_info() { return _jfr_info; })
1794 };
1795
1796 template <typename ConfigT>
1797 class Thaw : public ThawBase {
1798 public:
1799 Thaw(JavaThread* thread, ContinuationWrapper& cont) : ThawBase(thread, cont) {}
1800
1801 inline bool can_thaw_fast(stackChunkOop chunk) {
1802 return !_barriers
1803 && _thread->cont_fastpath_thread_state()
1804 && !chunk->has_thaw_slowpath_condition()
1805 && !PreserveFramePointer;
1806 }
1807
1808 inline intptr_t* thaw(Continuation::thaw_kind kind);
1809 NOINLINE intptr_t* thaw_fast(stackChunkOop chunk);
1810 inline void patch_caller_links(intptr_t* sp, intptr_t* bottom);
1811 };
1812
1813 template <typename ConfigT>
1814 inline intptr_t* Thaw<ConfigT>::thaw(Continuation::thaw_kind kind) {
1815 verify_continuation(_cont.continuation());
1816 assert(!jdk_internal_vm_Continuation::done(_cont.continuation()), "");
1817 assert(!_cont.is_empty(), "");
1818
1819 stackChunkOop chunk = _cont.tail();
1820 assert(chunk != nullptr, "guaranteed by prepare_thaw");
1821 assert(!chunk->is_empty(), "guaranteed by prepare_thaw");
1822
1823 _barriers = chunk->requires_barriers();
1824 return (LIKELY(can_thaw_fast(chunk))) ? thaw_fast(chunk)
1825 : thaw_slow(chunk, kind != Continuation::thaw_top);
1826 }
1827
1828 class ReconstructedStack : public StackObj {
1829 intptr_t* _base; // _cont.entrySP(); // top of the entry frame
1830 int _thaw_size;
1831 int _argsize;
1832 public:
1833 ReconstructedStack(intptr_t* base, int thaw_size, int argsize)
1834 : _base(base), _thaw_size(thaw_size - (argsize == 0 ? frame::metadata_words_at_top : 0)), _argsize(argsize) {
1835 // The only possible source of misalignment is stack-passed arguments b/c compiled frames are 16-byte aligned.
1836 assert(argsize != 0 || (_base - _thaw_size) == ContinuationHelper::frame_align_pointer(_base - _thaw_size), "");
1837 // We're at most one alignment word away from entrySP
1838 assert(_base - 1 <= top() + total_size() + frame::metadata_words_at_bottom, "missed entry frame");
1839 }
1840
1841 int entry_frame_extension() const { return _argsize + (_argsize > 0 ? frame::metadata_words_at_top : 0); }
1842
1843 // top and bottom stack pointers
1844 intptr_t* sp() const { return ContinuationHelper::frame_align_pointer(_base - _thaw_size); }
1845 intptr_t* bottom_sp() const { return ContinuationHelper::frame_align_pointer(_base - entry_frame_extension()); }
1846
1847 // several operations operate on the totality of the stack being reconstructed,
1848 // including the metadata words
1849 intptr_t* top() const { return sp() - frame::metadata_words_at_bottom; }
1850 int total_size() const { return _thaw_size + frame::metadata_words_at_bottom; }
1851 };
1852
1853 inline void ThawBase::clear_chunk(stackChunkOop chunk) {
1854 chunk->set_sp(chunk->bottom());
1855 chunk->set_max_thawing_size(0);
1856 }
1857
1858 int ThawBase::remove_top_compiled_frame_from_chunk(stackChunkOop chunk, int &argsize) {
1859 bool empty = false;
1860 StackChunkFrameStream<ChunkFrames::CompiledOnly> f(chunk);
1861 DEBUG_ONLY(intptr_t* const chunk_sp = chunk->start_address() + chunk->sp();)
1862 assert(chunk_sp == f.sp(), "");
1863 assert(chunk_sp == f.unextended_sp(), "");
1864
1865 const int frame_size = f.cb()->frame_size();
1866 argsize = f.stack_argsize();
1867
1868 f.next(SmallRegisterMap::instance, true /* stop */);
1869 empty = f.is_done();
1870 assert(!empty || argsize == chunk->argsize(), "");
1871
1872 if (empty) {
1873 clear_chunk(chunk);
1874 } else {
1875 chunk->set_sp(chunk->sp() + frame_size);
1876 chunk->set_max_thawing_size(chunk->max_thawing_size() - frame_size);
1877 // We set chunk->pc to the return pc into the next frame
1878 chunk->set_pc(f.pc());
1879 #ifdef ASSERT
1880 {
1881 intptr_t* retaddr_slot = (chunk_sp
1882 + frame_size
1883 - frame::sender_sp_ret_address_offset());
1884 assert(f.pc() == ContinuationHelper::return_address_at(retaddr_slot),
1885 "unexpected pc");
1886 }
1887 #endif
1888 }
1889 assert(empty == chunk->is_empty(), "");
1890 // returns the size required to store the frame on stack, and because it is a
1891 // compiled frame, it must include a copy of the arguments passed by the caller
1892 return frame_size + argsize + frame::metadata_words_at_top;
1893 }
1894
1895 void ThawBase::copy_from_chunk(intptr_t* from, intptr_t* to, int size) {
1896 assert(to >= _top_stack_address, "overwrote past thawing space"
1897 " to: " INTPTR_FORMAT " top_address: " INTPTR_FORMAT, p2i(to), p2i(_top_stack_address));
1898 assert(to + size <= _cont.entrySP(), "overwrote past thawing space");
1899 _cont.tail()->copy_from_chunk_to_stack(from, to, size);
1900 CONT_JFR_ONLY(_jfr_info.record_size_copied(size);)
1901 }
1902
1903 void ThawBase::patch_return(intptr_t* sp, bool is_last) {
1904 log_develop_trace(continuations)("thaw_fast patching -- sp: " INTPTR_FORMAT, p2i(sp));
1905
1906 address pc = !is_last ? StubRoutines::cont_returnBarrier() : _cont.entryPC();
1907 ContinuationHelper::patch_return_address_at(
1908 sp - frame::sender_sp_ret_address_offset(),
1909 pc);
1910 }
1911
1912 template <typename ConfigT>
1913 NOINLINE intptr_t* Thaw<ConfigT>::thaw_fast(stackChunkOop chunk) {
1914 assert(chunk == _cont.tail(), "");
1915 assert(!chunk->has_mixed_frames(), "");
1916 assert(!chunk->requires_barriers(), "");
1917 assert(!chunk->has_bitmap(), "");
1918 assert(!_thread->is_interp_only_mode(), "");
1919
1920 LogTarget(Trace, continuations) lt;
1921 if (lt.develop_is_enabled()) {
1922 LogStream ls(lt);
1923 ls.print_cr("thaw_fast");
1924 chunk->print_on(true, &ls);
1925 }
1926
1927 // Below this heuristic, we thaw the whole chunk, above it we thaw just one frame.
1928 static const int threshold = 500; // words
1929
1930 const int full_chunk_size = chunk->stack_size() - chunk->sp(); // this initial size could be reduced if it's a partial thaw
1931 int argsize, thaw_size;
1932
1933 intptr_t* const chunk_sp = chunk->start_address() + chunk->sp();
1934
1935 bool partial, empty;
1936 if (LIKELY(!TEST_THAW_ONE_CHUNK_FRAME && (full_chunk_size < threshold))) {
1937 prefetch_chunk_pd(chunk->start_address(), full_chunk_size); // prefetch anticipating memcpy starting at highest address
1938
1939 partial = false;
1940 argsize = chunk->argsize(); // must be called *before* clearing the chunk
1941 clear_chunk(chunk);
1942 thaw_size = full_chunk_size;
1943 empty = true;
1944 } else { // thaw a single frame
1945 partial = true;
1946 thaw_size = remove_top_compiled_frame_from_chunk(chunk, argsize);
1947 empty = chunk->is_empty();
1948 }
1949
1950 // Are we thawing the last frame(s) in the continuation
1951 const bool is_last = empty && chunk->parent() == nullptr;
1952 assert(!is_last || argsize == 0, "");
1953
1954 log_develop_trace(continuations)("thaw_fast partial: %d is_last: %d empty: %d size: %d argsize: %d entrySP: " PTR_FORMAT,
1955 partial, is_last, empty, thaw_size, argsize, p2i(_cont.entrySP()));
1956
1957 ReconstructedStack rs(_cont.entrySP(), thaw_size, argsize);
1958
1959 // also copy metadata words at frame bottom
1960 copy_from_chunk(chunk_sp - frame::metadata_words_at_bottom, rs.top(), rs.total_size());
1961
1962 // update the ContinuationEntry
1963 _cont.set_argsize(argsize);
1964 log_develop_trace(continuations)("setting entry argsize: %d", _cont.argsize());
1965 assert(rs.bottom_sp() == _cont.entry()->bottom_sender_sp(), "");
1966
1967 // install the return barrier if not last frame, or the entry's pc if last
1968 patch_return(rs.bottom_sp(), is_last);
1969
1970 // insert the back links from callee to caller frames
1971 patch_caller_links(rs.top(), rs.top() + rs.total_size());
1972
1973 assert(is_last == _cont.is_empty(), "");
1974 assert(_cont.chunk_invariant(), "");
1975
1976 #if CONT_JFR
1977 EventContinuationThawFast e;
1978 if (e.should_commit()) {
1979 e.set_id(cast_from_oop<u8>(chunk));
1980 e.set_size(thaw_size << LogBytesPerWord);
1981 e.set_full(!partial);
1982 e.commit();
1983 }
1984 #endif
1985
1986 #ifdef ASSERT
1987 set_anchor(_thread, rs.sp());
1988 log_frames(_thread);
1989 if (LoomDeoptAfterThaw) {
1990 do_deopt_after_thaw(_thread);
1991 }
1992 clear_anchor(_thread);
1993 #endif
1994
1995 return rs.sp();
1996 }
1997
1998 inline bool ThawBase::seen_by_gc() {
1999 return _barriers || _cont.tail()->is_gc_mode();
2000 }
2001
2002 NOINLINE intptr_t* ThawBase::thaw_slow(stackChunkOop chunk, bool return_barrier) {
2003 LogTarget(Trace, continuations) lt;
2004 if (lt.develop_is_enabled()) {
2005 LogStream ls(lt);
2006 ls.print_cr("thaw slow return_barrier: %d " INTPTR_FORMAT, return_barrier, p2i(chunk));
2007 chunk->print_on(true, &ls);
2008 }
2009
2010 #if CONT_JFR
2011 EventContinuationThawSlow e;
2012 if (e.should_commit()) {
2013 e.set_id(cast_from_oop<u8>(_cont.continuation()));
2014 e.commit();
2015 }
2016 #endif
2017
2018 DEBUG_ONLY(_frames = 0;)
2019 _align_size = 0;
2020 int num_frames = (return_barrier ? 1 : 2);
2021
2022 _stream = StackChunkFrameStream<ChunkFrames::Mixed>(chunk);
2023 _top_unextended_sp_before_thaw = _stream.unextended_sp();
2024
2025 frame heap_frame = _stream.to_frame();
2026 if (lt.develop_is_enabled()) {
2027 LogStream ls(lt);
2028 ls.print_cr("top hframe before (thaw):");
2029 assert(heap_frame.is_heap_frame(), "should have created a relative frame");
2030 heap_frame.print_value_on(&ls, nullptr);
2031 }
2032
2033 #if INCLUDE_ZGC || INCLUDE_SHENANDOAHGC
2034 if (UseZGC || UseShenandoahGC) {
2035 _cont.tail()->relativize_derived_pointers_concurrently();
2036 }
2037 #endif
2038
2039 frame caller; // the thawed caller on the stack
2040 recurse_thaw(heap_frame, caller, num_frames, true);
2041 finish_thaw(caller); // caller is now the topmost thawed frame
2042 _cont.write();
2043
2044 assert(_cont.chunk_invariant(), "");
2045
2046 JVMTI_ONLY(if (!return_barrier) invalidate_jvmti_stack(_thread));
2047
2048 _thread->set_cont_fastpath(_fastpath);
2049
2050 intptr_t* sp = caller.sp();
2051 return sp;
2052 }
2053
2054 void ThawBase::recurse_thaw(const frame& heap_frame, frame& caller, int num_frames, bool top) {
2055 log_develop_debug(continuations)("thaw num_frames: %d", num_frames);
2056 assert(!_cont.is_empty(), "no more frames");
2057 assert(num_frames > 0, "");
2058 assert(!heap_frame.is_empty(), "");
2059
2060 if (top && heap_frame.is_safepoint_blob_frame()) {
2061 assert(ContinuationHelper::Frame::is_stub(heap_frame.cb()), "cb: %s", heap_frame.cb()->name());
2062 recurse_thaw_stub_frame(heap_frame, caller, num_frames);
2063 } else if (!heap_frame.is_interpreted_frame()) {
2064 recurse_thaw_compiled_frame(heap_frame, caller, num_frames, false);
2065 } else {
2066 recurse_thaw_interpreted_frame(heap_frame, caller, num_frames);
2067 }
2068 }
2069
2070 template<typename FKind>
2071 bool ThawBase::recurse_thaw_java_frame(frame& caller, int num_frames) {
2072 assert(num_frames > 0, "");
2073
2074 DEBUG_ONLY(_frames++;)
2075
2076 int argsize = _stream.stack_argsize();
2077
2078 _stream.next(SmallRegisterMap::instance);
2079 assert(_stream.to_frame().is_empty() == _stream.is_done(), "");
2080
2081 // we never leave a compiled caller of an interpreted frame as the top frame in the chunk
2082 // as it makes detecting that situation and adjusting unextended_sp tricky
2083 if (num_frames == 1 && !_stream.is_done() && FKind::interpreted && _stream.is_compiled()) {
2084 log_develop_trace(continuations)("thawing extra compiled frame to not leave a compiled interpreted-caller at top");
2085 num_frames++;
2086 }
2087
2088 if (num_frames == 1 || _stream.is_done()) { // end recursion
2089 finalize_thaw(caller, FKind::interpreted ? 0 : argsize);
2090 return true; // bottom
2091 } else { // recurse
2092 recurse_thaw(_stream.to_frame(), caller, num_frames - 1, false);
2093 return false;
2094 }
2095 }
2096
2097 void ThawBase::finalize_thaw(frame& entry, int argsize) {
2098 stackChunkOop chunk = _cont.tail();
2099
2100 if (!_stream.is_done()) {
2101 assert(_stream.sp() >= chunk->sp_address(), "");
2102 chunk->set_sp(chunk->to_offset(_stream.sp()));
2103 chunk->set_pc(_stream.pc());
2104 } else {
2105 chunk->set_sp(chunk->bottom());
2106 chunk->set_pc(nullptr);
2107 }
2108 assert(_stream.is_done() == chunk->is_empty(), "");
2109
2110 int total_thawed = pointer_delta_as_int(_stream.unextended_sp(), _top_unextended_sp_before_thaw);
2111 chunk->set_max_thawing_size(chunk->max_thawing_size() - total_thawed);
2112
2113 _cont.set_argsize(argsize);
2114 entry = new_entry_frame();
2115
2116 assert(entry.sp() == _cont.entrySP(), "");
2117 assert(Continuation::is_continuation_enterSpecial(entry), "");
2118 assert(_cont.is_entry_frame(entry), "");
2119 }
2120
2121 inline void ThawBase::before_thaw_java_frame(const frame& hf, const frame& caller, bool bottom, int num_frame) {
2122 LogTarget(Trace, continuations) lt;
2123 if (lt.develop_is_enabled()) {
2124 LogStream ls(lt);
2125 ls.print_cr("======== THAWING FRAME: %d", num_frame);
2126 assert(hf.is_heap_frame(), "should be");
2127 hf.print_value_on(&ls, nullptr);
2128 }
2129 assert(bottom == _cont.is_entry_frame(caller), "bottom: %d is_entry_frame: %d", bottom, _cont.is_entry_frame(hf));
2130 }
2131
2132 inline void ThawBase::after_thaw_java_frame(const frame& f, bool bottom) {
2133 #ifdef ASSERT
2134 LogTarget(Trace, continuations) lt;
2135 if (lt.develop_is_enabled()) {
2136 LogStream ls(lt);
2137 ls.print_cr("thawed frame:");
2138 print_frame_layout(f, false, &ls); // f.print_on(&ls);
2139 }
2140 #endif
2141 }
2142
2143 inline void ThawBase::patch(frame& f, const frame& caller, bool bottom) {
2144 assert(!bottom || caller.fp() == _cont.entryFP(), "");
2145 if (bottom) {
2146 ContinuationHelper::Frame::patch_pc(caller, _cont.is_empty() ? caller.pc()
2147 : StubRoutines::cont_returnBarrier());
2148 } else {
2149 // caller might have been deoptimized during thaw but we've overwritten the return address when copying f from the heap.
2150 // If the caller is not deoptimized, pc is unchanged.
2151 ContinuationHelper::Frame::patch_pc(caller, caller.raw_pc());
2152 }
2153
2154 patch_pd(f, caller);
2155
2156 if (f.is_interpreted_frame()) {
2157 ContinuationHelper::InterpretedFrame::patch_sender_sp(f, caller);
2158 }
2159
2160 assert(!bottom || !_cont.is_empty() || Continuation::is_continuation_entry_frame(f, nullptr), "");
2161 assert(!bottom || (_cont.is_empty() != Continuation::is_cont_barrier_frame(f)), "");
2162 }
2163
2164 void ThawBase::clear_bitmap_bits(address start, address end) {
2165 assert(is_aligned(start, wordSize), "should be aligned: " PTR_FORMAT, p2i(start));
2166 assert(is_aligned(end, VMRegImpl::stack_slot_size), "should be aligned: " PTR_FORMAT, p2i(end));
2167
2168 // we need to clear the bits that correspond to arguments as they reside in the caller frame
2169 // or they will keep objects that are otherwise unreachable alive.
2170
2171 // Align `end` if UseCompressedOops is not set to avoid UB when calculating the bit index, since
2172 // `end` could be at an odd number of stack slots from `start`, i.e might not be oop aligned.
2173 // If that's the case the bit range corresponding to the last stack slot should not have bits set
2174 // anyways and we assert that before returning.
2175 address effective_end = UseCompressedOops ? end : align_down(end, wordSize);
2176 log_develop_trace(continuations)("clearing bitmap for " INTPTR_FORMAT " - " INTPTR_FORMAT, p2i(start), p2i(effective_end));
2177 stackChunkOop chunk = _cont.tail();
2178 chunk->bitmap().clear_range(chunk->bit_index_for(start), chunk->bit_index_for(effective_end));
2179 assert(effective_end == end || !chunk->bitmap().at(chunk->bit_index_for(effective_end)), "bit should not be set");
2180 }
2181
2182 NOINLINE void ThawBase::recurse_thaw_interpreted_frame(const frame& hf, frame& caller, int num_frames) {
2183 assert(hf.is_interpreted_frame(), "");
2184
2185 if (UNLIKELY(seen_by_gc())) {
2186 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance);
2187 }
2188
2189 const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::InterpretedFrame>(caller, num_frames);
2190
2191 DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2192
2193 _align_size += frame::align_wiggle; // possible added alignment for internal interpreted frame alignment om AArch64
2194
2195 frame f = new_stack_frame<ContinuationHelper::InterpretedFrame>(hf, caller, is_bottom_frame);
2196
2197 intptr_t* const stack_frame_top = f.sp() + frame::metadata_words_at_top;
2198 intptr_t* const stack_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(f);
2199 intptr_t* const heap_frame_top = hf.unextended_sp() + frame::metadata_words_at_top;
2200 intptr_t* const heap_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(hf);
2201
2202 assert(hf.is_heap_frame(), "should be");
2203 assert(!f.is_heap_frame(), "should not be");
2204
2205 const int fsize = pointer_delta_as_int(heap_frame_bottom, heap_frame_top);
2206 assert((stack_frame_bottom == stack_frame_top + fsize), "");
2207
2208 // Some architectures (like AArch64/PPC64/RISC-V) add padding between the locals and the fixed_frame to keep the fp 16-byte-aligned.
2209 // On those architectures we freeze the padding in order to keep the same fp-relative offsets in the fixed_frame.
2210 copy_from_chunk(heap_frame_top, stack_frame_top, fsize);
2211
2212 // Make sure the relativized locals is already set.
2213 assert(f.interpreter_frame_local_at(0) == stack_frame_bottom - 1, "invalid frame bottom");
2214
2215 derelativize_interpreted_frame_metadata(hf, f);
2216 patch(f, caller, is_bottom_frame);
2217
2218 assert(f.is_interpreted_frame_valid(_cont.thread()), "invalid thawed frame");
2219 assert(stack_frame_bottom <= ContinuationHelper::Frame::frame_top(caller), "");
2220
2221 CONT_JFR_ONLY(_jfr_info.record_interpreted_frame();)
2222
2223 maybe_set_fastpath(f.sp());
2224
2225 const int locals = hf.interpreter_frame_method()->max_locals();
2226
2227 if (!is_bottom_frame) {
2228 // can only fix caller once this frame is thawed (due to callee saved regs)
2229 _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance);
2230 } else if (_cont.tail()->has_bitmap() && locals > 0) {
2231 assert(hf.is_heap_frame(), "should be");
2232 address start = (address)(heap_frame_bottom - locals);
2233 address end = (address)heap_frame_bottom;
2234 clear_bitmap_bits(start, end);
2235 }
2236
2237 DEBUG_ONLY(after_thaw_java_frame(f, is_bottom_frame);)
2238 caller = f;
2239 }
2240
2241 void ThawBase::recurse_thaw_compiled_frame(const frame& hf, frame& caller, int num_frames, bool stub_caller) {
2242 assert(!hf.is_interpreted_frame(), "");
2243 assert(_cont.is_preempted() || !stub_caller, "stub caller not at preemption");
2244
2245 if (!stub_caller && UNLIKELY(seen_by_gc())) { // recurse_thaw_stub_frame already invoked our barriers with a full regmap
2246 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance);
2247 }
2248
2249 const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::CompiledFrame>(caller, num_frames);
2250
2251 DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2252
2253 assert(caller.sp() == caller.unextended_sp(), "");
2254
2255 if ((!is_bottom_frame && caller.is_interpreted_frame()) || (is_bottom_frame && Interpreter::contains(_cont.tail()->pc()))) {
2256 _align_size += frame::align_wiggle; // we add one whether or not we've aligned because we add it in freeze_interpreted_frame
2257 }
2258
2259 // new_stack_frame must construct the resulting frame using hf.pc() rather than hf.raw_pc() because the frame is not
2260 // yet laid out in the stack, and so the original_pc is not stored in it.
2261 // As a result, f.is_deoptimized_frame() is always false and we must test hf to know if the frame is deoptimized.
2262 frame f = new_stack_frame<ContinuationHelper::CompiledFrame>(hf, caller, is_bottom_frame);
2263 intptr_t* const stack_frame_top = f.sp();
2264 intptr_t* const heap_frame_top = hf.unextended_sp();
2265
2266 const int added_argsize = (is_bottom_frame || caller.is_interpreted_frame()) ? hf.compiled_frame_stack_argsize() : 0;
2267 int fsize = ContinuationHelper::CompiledFrame::size(hf) + added_argsize;
2268 assert(fsize <= (int)(caller.unextended_sp() - f.unextended_sp()), "");
2269
2270 intptr_t* from = heap_frame_top - frame::metadata_words_at_bottom;
2271 intptr_t* to = stack_frame_top - frame::metadata_words_at_bottom;
2272 // copy metadata, except the metadata at the top of the (unextended) entry frame
2273 int sz = fsize + frame::metadata_words_at_bottom + (is_bottom_frame && added_argsize == 0 ? 0 : frame::metadata_words_at_top);
2274
2275 // If we're the bottom-most thawed frame, we're writing to within one word from entrySP
2276 // (we might have one padding word for alignment)
2277 assert(!is_bottom_frame || (_cont.entrySP() - 1 <= to + sz && to + sz <= _cont.entrySP()), "");
2278 assert(!is_bottom_frame || hf.compiled_frame_stack_argsize() != 0 || (to + sz && to + sz == _cont.entrySP()), "");
2279
2280 copy_from_chunk(from, to, sz); // copying good oops because we invoked barriers above
2281
2282 patch(f, caller, is_bottom_frame);
2283
2284 // f.is_deoptimized_frame() is always false and we must test hf.is_deoptimized_frame() (see comment above)
2285 assert(!f.is_deoptimized_frame(), "");
2286 if (hf.is_deoptimized_frame()) {
2287 maybe_set_fastpath(f.sp());
2288 } else if (_thread->is_interp_only_mode()
2289 || (_cont.is_preempted() && f.cb()->as_nmethod()->is_marked_for_deoptimization())) {
2290 // The caller of the safepoint stub when the continuation is preempted is not at a call instruction, and so
2291 // cannot rely on nmethod patching for deopt.
2292 assert(_thread->is_interp_only_mode() || stub_caller, "expected a stub-caller");
2293
2294 log_develop_trace(continuations)("Deoptimizing thawed frame");
2295 DEBUG_ONLY(ContinuationHelper::Frame::patch_pc(f, nullptr));
2296
2297 f.deoptimize(nullptr); // the null thread simply avoids the assertion in deoptimize which we're not set up for
2298 assert(f.is_deoptimized_frame(), "");
2299 assert(ContinuationHelper::Frame::is_deopt_return(f.raw_pc(), f), "");
2300 maybe_set_fastpath(f.sp());
2301 }
2302
2303 if (!is_bottom_frame) {
2304 // can only fix caller once this frame is thawed (due to callee saved regs); this happens on the stack
2305 _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance);
2306 } else if (_cont.tail()->has_bitmap() && added_argsize > 0) {
2307 address start = (address)(heap_frame_top + ContinuationHelper::CompiledFrame::size(hf) + frame::metadata_words_at_top);
2308 int stack_args_slots = f.cb()->as_nmethod()->num_stack_arg_slots(false /* rounded */);
2309 int argsize_in_bytes = stack_args_slots * VMRegImpl::stack_slot_size;
2310 clear_bitmap_bits(start, start + argsize_in_bytes);
2311 }
2312
2313 DEBUG_ONLY(after_thaw_java_frame(f, is_bottom_frame);)
2314 caller = f;
2315 }
2316
2317 void ThawBase::recurse_thaw_stub_frame(const frame& hf, frame& caller, int num_frames) {
2318 DEBUG_ONLY(_frames++;)
2319
2320 {
2321 RegisterMap map(nullptr,
2322 RegisterMap::UpdateMap::include,
2323 RegisterMap::ProcessFrames::skip,
2324 RegisterMap::WalkContinuation::skip);
2325 map.set_include_argument_oops(false);
2326 _stream.next(&map);
2327 assert(!_stream.is_done(), "");
2328 if (UNLIKELY(seen_by_gc())) { // we're now doing this on the stub's caller
2329 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, &map);
2330 }
2331 assert(!_stream.is_done(), "");
2332 }
2333
2334 recurse_thaw_compiled_frame(_stream.to_frame(), caller, num_frames, true); // this could be deoptimized
2335
2336 DEBUG_ONLY(before_thaw_java_frame(hf, caller, false, num_frames);)
2337
2338 assert(ContinuationHelper::Frame::is_stub(hf.cb()), "");
2339 assert(caller.sp() == caller.unextended_sp(), "");
2340 assert(!caller.is_interpreted_frame(), "");
2341
2342 int fsize = ContinuationHelper::StubFrame::size(hf);
2343
2344 frame f = new_stack_frame<ContinuationHelper::StubFrame>(hf, caller, false);
2345 intptr_t* stack_frame_top = f.sp();
2346 intptr_t* heap_frame_top = hf.sp();
2347
2348 copy_from_chunk(heap_frame_top - frame::metadata_words, stack_frame_top - frame::metadata_words,
2349 fsize + frame::metadata_words);
2350
2351 { // can only fix caller once this frame is thawed (due to callee saved regs)
2352 RegisterMap map(nullptr,
2353 RegisterMap::UpdateMap::include,
2354 RegisterMap::ProcessFrames::skip,
2355 RegisterMap::WalkContinuation::skip); // map.clear();
2356 map.set_include_argument_oops(false);
2357 f.oop_map()->update_register_map(&f, &map);
2358 ContinuationHelper::update_register_map_with_callee(caller, &map);
2359 _cont.tail()->fix_thawed_frame(caller, &map);
2360 }
2361
2362 DEBUG_ONLY(after_thaw_java_frame(f, false);)
2363 caller = f;
2364 }
2365
2366 void ThawBase::finish_thaw(frame& f) {
2367 stackChunkOop chunk = _cont.tail();
2368
2369 if (chunk->is_empty()) {
2370 // Only remove chunk from list if it can't be reused for another freeze
2371 if (seen_by_gc()) {
2372 _cont.set_tail(chunk->parent());
2373 } else {
2374 chunk->set_has_mixed_frames(false);
2375 }
2376 chunk->set_max_thawing_size(0);
2377 } else {
2378 chunk->set_max_thawing_size(chunk->max_thawing_size() - _align_size);
2379 }
2380 assert(chunk->is_empty() == (chunk->max_thawing_size() == 0), "");
2381
2382 if (!is_aligned(f.sp(), frame::frame_alignment)) {
2383 assert(f.is_interpreted_frame(), "");
2384 f.set_sp(align_down(f.sp(), frame::frame_alignment));
2385 }
2386 push_return_frame(f);
2387 chunk->fix_thawed_frame(f, SmallRegisterMap::instance); // can only fix caller after push_return_frame (due to callee saved regs)
2388
2389 assert(_cont.is_empty() == _cont.last_frame().is_empty(), "");
2390
2391 log_develop_trace(continuations)("thawed %d frames", _frames);
2392
2393 LogTarget(Trace, continuations) lt;
2394 if (lt.develop_is_enabled()) {
2395 LogStream ls(lt);
2396 ls.print_cr("top hframe after (thaw):");
2397 _cont.last_frame().print_value_on(&ls, nullptr);
2398 }
2399 }
2400
2401 void ThawBase::push_return_frame(frame& f) { // see generate_cont_thaw
2402 assert(!f.is_compiled_frame() || f.is_deoptimized_frame() == f.cb()->as_nmethod()->is_deopt_pc(f.raw_pc()), "");
2403 assert(!f.is_compiled_frame() || f.is_deoptimized_frame() == (f.pc() != f.raw_pc()), "");
2404
2405 LogTarget(Trace, continuations) lt;
2406 if (lt.develop_is_enabled()) {
2407 LogStream ls(lt);
2408 ls.print_cr("push_return_frame");
2409 f.print_value_on(&ls, nullptr);
2410 }
2411
2412 assert(f.sp() - frame::metadata_words_at_bottom >= _top_stack_address, "overwrote past thawing space"
2413 " to: " INTPTR_FORMAT " top_address: " INTPTR_FORMAT, p2i(f.sp() - frame::metadata_words), p2i(_top_stack_address));
2414 ContinuationHelper::Frame::patch_pc(f, f.raw_pc()); // in case we want to deopt the frame in a full transition, this is checked.
2415 ContinuationHelper::push_pd(f);
2416
2417 assert(ContinuationHelper::Frame::assert_frame_laid_out(f), "");
2418 }
2419
2420 // returns new top sp
2421 // called after preparations (stack overflow check and making room)
2422 template<typename ConfigT>
2423 static inline intptr_t* thaw_internal(JavaThread* thread, const Continuation::thaw_kind kind) {
2424 assert(thread == JavaThread::current(), "Must be current thread");
2425
2426 CONT_JFR_ONLY(EventContinuationThaw event;)
2427
2428 log_develop_trace(continuations)("~~~~ thaw kind: %d sp: " INTPTR_FORMAT, kind, p2i(thread->last_continuation()->entry_sp()));
2429
2430 ContinuationEntry* entry = thread->last_continuation();
2431 assert(entry != nullptr, "");
2432 oop oopCont = entry->cont_oop(thread);
2433
2434 assert(!jdk_internal_vm_Continuation::done(oopCont), "");
2435 assert(oopCont == get_continuation(thread), "");
2436 verify_continuation(oopCont);
2437
2438 assert(entry->is_virtual_thread() == (entry->scope(thread) == java_lang_VirtualThread::vthread_scope()), "");
2439
2440 ContinuationWrapper cont(thread, oopCont);
2441 log_develop_debug(continuations)("THAW #" INTPTR_FORMAT " " INTPTR_FORMAT, cont.hash(), p2i((oopDesc*)oopCont));
2442
2443 #ifdef ASSERT
2444 set_anchor_to_entry(thread, cont.entry());
2445 log_frames(thread);
2446 clear_anchor(thread);
2447 #endif
2448
2449 Thaw<ConfigT> thw(thread, cont);
2450 intptr_t* const sp = thw.thaw(kind);
2451 assert(is_aligned(sp, frame::frame_alignment), "");
2452
2453 // All or part of the frames have been thawed so we know they don't hold any monitors except JNI monitors.
2454 assert(thread->held_monitor_count() == thread->jni_monitor_count(), "Must be");
2455
2456 #ifdef ASSERT
2457 intptr_t* sp0 = sp;
2458 set_anchor(thread, sp0);
2459 log_frames(thread);
2460 if (LoomVerifyAfterThaw) {
2461 assert(do_verify_after_thaw(thread, cont.tail(), tty), "");
2462 }
2463 assert(ContinuationEntry::assert_entry_frame_laid_out(thread), "");
2464 clear_anchor(thread);
2465
2466 LogTarget(Trace, continuations) lt;
2467 if (lt.develop_is_enabled()) {
2468 LogStream ls(lt);
2469 ls.print_cr("Jumping to frame (thaw):");
2470 frame(sp).print_value_on(&ls, nullptr);
2471 }
2472 #endif
2473
2474 CONT_JFR_ONLY(thw.jfr_info().post_jfr_event(&event, cont.continuation(), thread);)
2475
2476 verify_continuation(cont.continuation());
2477 log_develop_debug(continuations)("=== End of thaw #" INTPTR_FORMAT, cont.hash());
2478
2479 return sp;
2480 }
2481
2482 #ifdef ASSERT
2483 static void do_deopt_after_thaw(JavaThread* thread) {
2484 int i = 0;
2485 StackFrameStream fst(thread, true, false);
2486 fst.register_map()->set_include_argument_oops(false);
2487 ContinuationHelper::update_register_map_with_callee(*fst.current(), fst.register_map());
2488 for (; !fst.is_done(); fst.next()) {
2489 if (fst.current()->cb()->is_nmethod()) {
2490 nmethod* nm = fst.current()->cb()->as_nmethod();
2491 if (!nm->method()->is_continuation_native_intrinsic()) {
2492 nm->make_deoptimized();
2493 }
2494 }
2495 }
2496 }
2497
2498 class ThawVerifyOopsClosure: public OopClosure {
2499 intptr_t* _p;
2500 outputStream* _st;
2501 bool is_good_oop(oop o) {
2502 return dbg_is_safe(o, -1) && dbg_is_safe(o->klass(), -1) && oopDesc::is_oop(o) && o->klass()->is_klass();
2503 }
2504 public:
2505 ThawVerifyOopsClosure(outputStream* st) : _p(nullptr), _st(st) {}
2506 intptr_t* p() { return _p; }
2507 void reset() { _p = nullptr; }
2508
2509 virtual void do_oop(oop* p) {
2510 oop o = *p;
2511 if (o == nullptr || is_good_oop(o)) {
2512 return;
2513 }
2514 _p = (intptr_t*)p;
2515 _st->print_cr("*** non-oop " PTR_FORMAT " found at " PTR_FORMAT, p2i(*p), p2i(p));
2516 }
2517 virtual void do_oop(narrowOop* p) {
2518 oop o = RawAccess<>::oop_load(p);
2519 if (o == nullptr || is_good_oop(o)) {
2520 return;
2521 }
2522 _p = (intptr_t*)p;
2523 _st->print_cr("*** (narrow) non-oop %x found at " PTR_FORMAT, (int)(*p), p2i(p));
2524 }
2525 };
2526
2527 static bool do_verify_after_thaw(JavaThread* thread, stackChunkOop chunk, outputStream* st) {
2528 assert(thread->has_last_Java_frame(), "");
2529
2530 ResourceMark rm;
2531 ThawVerifyOopsClosure cl(st);
2532 NMethodToOopClosure cf(&cl, false);
2533
2534 StackFrameStream fst(thread, true, false);
2535 fst.register_map()->set_include_argument_oops(false);
2536 ContinuationHelper::update_register_map_with_callee(*fst.current(), fst.register_map());
2537 for (; !fst.is_done() && !Continuation::is_continuation_enterSpecial(*fst.current()); fst.next()) {
2538 if (fst.current()->cb()->is_nmethod() && fst.current()->cb()->as_nmethod()->is_marked_for_deoptimization()) {
2539 st->print_cr(">>> do_verify_after_thaw deopt");
2540 fst.current()->deoptimize(nullptr);
2541 fst.current()->print_on(st);
2542 }
2543
2544 fst.current()->oops_do(&cl, &cf, fst.register_map());
2545 if (cl.p() != nullptr) {
2546 frame fr = *fst.current();
2547 st->print_cr("Failed for frame barriers: %d",chunk->requires_barriers());
2548 fr.print_on(st);
2549 if (!fr.is_interpreted_frame()) {
2550 st->print_cr("size: %d argsize: %d",
2551 ContinuationHelper::NonInterpretedUnknownFrame::size(fr),
2552 ContinuationHelper::NonInterpretedUnknownFrame::stack_argsize(fr));
2553 }
2554 VMReg reg = fst.register_map()->find_register_spilled_here(cl.p(), fst.current()->sp());
2555 if (reg != nullptr) {
2556 st->print_cr("Reg %s %d", reg->name(), reg->is_stack() ? (int)reg->reg2stack() : -99);
2557 }
2558 cl.reset();
2559 DEBUG_ONLY(thread->print_frame_layout();)
2560 if (chunk != nullptr) {
2561 chunk->print_on(true, st);
2562 }
2563 return false;
2564 }
2565 }
2566 return true;
2567 }
2568
2569 static void log_frames(JavaThread* thread) {
2570 const static int show_entry_callers = 3;
2571 LogTarget(Trace, continuations) lt;
2572 if (!lt.develop_is_enabled()) {
2573 return;
2574 }
2575 LogStream ls(lt);
2576
2577 ls.print_cr("------- frames ---------");
2578 if (!thread->has_last_Java_frame()) {
2579 ls.print_cr("NO ANCHOR!");
2580 }
2581
2582 RegisterMap map(thread,
2583 RegisterMap::UpdateMap::include,
2584 RegisterMap::ProcessFrames::include,
2585 RegisterMap::WalkContinuation::skip);
2586 map.set_include_argument_oops(false);
2587
2588 if (false) {
2589 for (frame f = thread->last_frame(); !f.is_entry_frame(); f = f.sender(&map)) {
2590 f.print_on(&ls);
2591 }
2592 } else {
2593 map.set_skip_missing(true);
2594 ResetNoHandleMark rnhm;
2595 ResourceMark rm;
2596 HandleMark hm(Thread::current());
2597 FrameValues values;
2598
2599 int i = 0;
2600 int post_entry = -1;
2601 for (frame f = thread->last_frame(); !f.is_entry_frame(); f = f.sender(&map)) {
2602 f.describe(values, i++, &map);
2603 if (post_entry >= 0 || Continuation::is_continuation_enterSpecial(f))
2604 post_entry++;
2605 if (post_entry >= show_entry_callers)
2606 break;
2607 }
2608 values.print_on(thread, &ls);
2609 }
2610
2611 ls.print_cr("======= end frames =========");
2612 }
2613 #endif // ASSERT
2614
2615 #include CPU_HEADER_INLINE(continuationFreezeThaw)
2616
2617 #ifdef ASSERT
2618 static void print_frame_layout(const frame& f, bool callee_complete, outputStream* st) {
2619 ResourceMark rm;
2620 FrameValues values;
2621 assert(f.get_cb() != nullptr, "");
2622 RegisterMap map(f.is_heap_frame() ?
2623 nullptr :
2624 JavaThread::current(),
2625 RegisterMap::UpdateMap::include,
2626 RegisterMap::ProcessFrames::skip,
2627 RegisterMap::WalkContinuation::skip);
2628 map.set_include_argument_oops(false);
2629 map.set_skip_missing(true);
2630 if (callee_complete) {
2631 frame::update_map_with_saved_link(&map, ContinuationHelper::Frame::callee_link_address(f));
2632 }
2633 const_cast<frame&>(f).describe(values, 0, &map);
2634 values.print_on(static_cast<JavaThread*>(nullptr), st);
2635 }
2636 #endif
2637
2638 static address thaw_entry = nullptr;
2639 static address freeze_entry = nullptr;
2640
2641 address Continuation::thaw_entry() {
2642 return ::thaw_entry;
2643 }
2644
2645 address Continuation::freeze_entry() {
2646 return ::freeze_entry;
2647 }
2648
2649 class ConfigResolve {
2650 public:
2651 static void resolve() { resolve_compressed(); }
2652
2653 static void resolve_compressed() {
2654 UseCompressedOops ? resolve_gc<true>()
2655 : resolve_gc<false>();
2656 }
2657
2658 private:
2659 template <bool use_compressed>
2660 static void resolve_gc() {
2661 BarrierSet* bs = BarrierSet::barrier_set();
2662 assert(bs != nullptr, "freeze/thaw invoked before BarrierSet is set");
2663 switch (bs->kind()) {
2664 #define BARRIER_SET_RESOLVE_BARRIER_CLOSURE(bs_name) \
2665 case BarrierSet::bs_name: { \
2666 resolve<use_compressed, typename BarrierSet::GetType<BarrierSet::bs_name>::type>(); \
2667 } \
2668 break;
2669 FOR_EACH_CONCRETE_BARRIER_SET_DO(BARRIER_SET_RESOLVE_BARRIER_CLOSURE)
2670 #undef BARRIER_SET_RESOLVE_BARRIER_CLOSURE
2671
2672 default:
2673 fatal("BarrierSet resolving not implemented");
2674 };
2675 }
2676
2677 template <bool use_compressed, typename BarrierSetT>
2678 static void resolve() {
2679 typedef Config<use_compressed ? oop_kind::NARROW : oop_kind::WIDE, BarrierSetT> SelectedConfigT;
2680
2681 freeze_entry = (address)freeze<SelectedConfigT>;
2682
2683 // If we wanted, we could templatize by kind and have three different thaw entries
2684 thaw_entry = (address)thaw<SelectedConfigT>;
2685 }
2686 };
2687
2688 void Continuation::init() {
2689 ConfigResolve::resolve();
2690 }