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) = 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 #ifdef ASSERT
443 bool is_empty(stackChunkOop chunk) {
444 // during freeze, the chunk is in an intermediate state (after setting the chunk's argsize but before setting its
445 // ultimate sp) so we use this instead of stackChunkOopDesc::is_empty
446 return chunk->sp() >= chunk->stack_size() - chunk->argsize() - frame::metadata_words_at_top;
447 }
448 #endif
449 };
450
451 template <typename ConfigT>
452 class Freeze : public FreezeBase {
453 private:
454 stackChunkOop allocate_chunk(size_t stack_size);
455
456 public:
457 inline Freeze(JavaThread* thread, ContinuationWrapper& cont, intptr_t* frame_sp)
458 : FreezeBase(thread, cont, frame_sp) {}
459
460 freeze_result try_freeze_fast();
461
462 protected:
463 virtual stackChunkOop allocate_chunk_slow(size_t stack_size) override { return allocate_chunk(stack_size); }
464 };
465
466 FreezeBase::FreezeBase(JavaThread* thread, ContinuationWrapper& cont, intptr_t* frame_sp) :
467 _thread(thread), _cont(cont), _barriers(false), _preempt(false), _frame_sp(frame_sp) {
468 DEBUG_ONLY(_jvmti_event_collector = nullptr;)
469
470 assert(_thread != nullptr, "");
471 assert(_thread->last_continuation()->entry_sp() == _cont.entrySP(), "");
472
473 DEBUG_ONLY(_cont.entry()->verify_cookie();)
474
475 assert(!Interpreter::contains(_cont.entryPC()), "");
476
477 _bottom_address = _cont.entrySP() - _cont.entry_frame_extension();
478 #ifdef _LP64
479 if (((intptr_t)_bottom_address & 0xf) != 0) {
480 _bottom_address--;
481 }
482 assert(is_aligned(_bottom_address, frame::frame_alignment), "");
483 #endif
484
485 log_develop_trace(continuations)("bottom_address: " INTPTR_FORMAT " entrySP: " INTPTR_FORMAT " argsize: " PTR_FORMAT,
486 p2i(_bottom_address), p2i(_cont.entrySP()), (_cont.entrySP() - _bottom_address) << LogBytesPerWord);
487 assert(_bottom_address != nullptr, "");
488 assert(_bottom_address <= _cont.entrySP(), "");
489 DEBUG_ONLY(_last_write = nullptr;)
490
491 assert(_cont.chunk_invariant(), "");
492 assert(!Interpreter::contains(_cont.entryPC()), "");
493 #if !defined(PPC64) || defined(ZERO)
494 static const int doYield_stub_frame_size = frame::metadata_words;
495 #else
496 static const int doYield_stub_frame_size = frame::native_abi_reg_args_size >> LogBytesPerWord;
497 #endif
498 assert(SharedRuntime::cont_doYield_stub()->frame_size() == doYield_stub_frame_size, "");
499
500 // properties of the continuation on the stack; all sizes are in words
501 _cont_stack_top = frame_sp + doYield_stub_frame_size; // we don't freeze the doYield stub frame
502 _cont_stack_bottom = _cont.entrySP() + (_cont.argsize() == 0 ? frame::metadata_words_at_top : 0)
503 - ContinuationHelper::frame_align_words(_cont.argsize()); // see alignment in thaw
504
505 log_develop_trace(continuations)("freeze size: %d argsize: %d top: " INTPTR_FORMAT " bottom: " INTPTR_FORMAT,
506 cont_size(), _cont.argsize(), p2i(_cont_stack_top), p2i(_cont_stack_bottom));
507 assert(cont_size() > 0, "");
508 }
509
510 void FreezeBase::init_rest() { // we want to postpone some initialization after chunk handling
511 _freeze_size = 0;
512 _total_align_size = 0;
513 NOT_PRODUCT(_frames = 0;)
514 }
515
516 void FreezeBase::copy_to_chunk(intptr_t* from, intptr_t* to, int size) {
517 stackChunkOop chunk = _cont.tail();
518 chunk->copy_from_stack_to_chunk(from, to, size);
519 CONT_JFR_ONLY(_jfr_info.record_size_copied(size);)
520
521 #ifdef ASSERT
522 if (_last_write != nullptr) {
523 assert(_last_write == to + size, "Missed a spot: _last_write: " INTPTR_FORMAT " to+size: " INTPTR_FORMAT
524 " stack_size: %d _last_write offset: " PTR_FORMAT " to+size: " PTR_FORMAT, p2i(_last_write), p2i(to+size),
525 chunk->stack_size(), _last_write-chunk->start_address(), to+size-chunk->start_address());
526 _last_write = to;
527 }
528 #endif
529 }
530
531 // Called _after_ the last possible safepoint during the freeze operation (chunk allocation)
532 void FreezeBase::unwind_frames() {
533 ContinuationEntry* entry = _cont.entry();
534 entry->flush_stack_processing(_thread);
535 set_anchor_to_entry(_thread, entry);
536 }
537
538 template <typename ConfigT>
539 freeze_result Freeze<ConfigT>::try_freeze_fast() {
540 assert(_thread->thread_state() == _thread_in_vm, "");
541 assert(_thread->cont_fastpath(), "");
542
543 DEBUG_ONLY(_fast_freeze_size = size_if_fast_freeze_available();)
544 assert(_fast_freeze_size == 0, "");
545
546 stackChunkOop chunk = allocate_chunk(cont_size() + frame::metadata_words);
547 if (freeze_fast_new_chunk(chunk)) {
548 return freeze_ok;
549 }
550 if (_thread->has_pending_exception()) {
551 return freeze_exception;
552 }
553
554 // TODO R REMOVE when deopt change is fixed
555 assert(!_thread->cont_fastpath() || _barriers, "");
556 log_develop_trace(continuations)("-- RETRYING SLOW --");
557 return freeze_slow();
558 }
559
560 // Returns size needed if the continuation fits, otherwise 0.
561 int FreezeBase::size_if_fast_freeze_available() {
562 stackChunkOop chunk = _cont.tail();
563 if (chunk == nullptr || chunk->is_gc_mode() || chunk->requires_barriers() || chunk->has_mixed_frames()) {
564 log_develop_trace(continuations)("chunk available %s", chunk == nullptr ? "no chunk" : "chunk requires barriers");
565 return 0;
566 }
567
568 int total_size_needed = cont_size();
569 const int chunk_sp = chunk->sp();
570
571 // argsize can be nonzero if we have a caller, but the caller could be in a non-empty parent chunk,
572 // so we subtract it only if we overlap with the caller, i.e. the current chunk isn't empty.
573 // Consider leaving the chunk's argsize set when emptying it and removing the following branch,
574 // although that would require changing stackChunkOopDesc::is_empty
575 if (chunk_sp < chunk->stack_size()) {
576 total_size_needed -= _cont.argsize() + frame::metadata_words_at_top;
577 }
578
579 int chunk_free_room = chunk_sp - frame::metadata_words_at_bottom;
580 bool available = chunk_free_room >= total_size_needed;
581 log_develop_trace(continuations)("chunk available: %s size: %d argsize: %d top: " INTPTR_FORMAT " bottom: " INTPTR_FORMAT,
582 available ? "yes" : "no" , total_size_needed, _cont.argsize(), p2i(_cont_stack_top), p2i(_cont_stack_bottom));
583 return available ? total_size_needed : 0;
584 }
585
586 void FreezeBase::freeze_fast_existing_chunk() {
587 stackChunkOop chunk = _cont.tail();
588 DEBUG_ONLY(_orig_chunk_sp = chunk->sp_address();)
589
590 DEBUG_ONLY(_fast_freeze_size = size_if_fast_freeze_available();)
591 assert(_fast_freeze_size > 0, "");
592
593 if (chunk->sp() < chunk->stack_size()) { // we are copying into a non-empty chunk
594 DEBUG_ONLY(_empty = false;)
595 assert(chunk->sp() < (chunk->stack_size() - chunk->argsize()), "");
596 #ifdef ASSERT
597 {
598 intptr_t* retaddr_slot = (chunk->sp_address()
599 - frame::sender_sp_ret_address_offset());
600 assert(ContinuationHelper::return_address_at(retaddr_slot) == chunk->pc(),
601 "unexpected saved return address");
602 }
603 #endif
604
605 // the chunk's sp before the freeze, adjusted to point beyond the stack-passed arguments in the topmost frame
606 // we overlap; we'll overwrite the chunk's top frame's callee arguments
607 const int chunk_start_sp = chunk->sp() + _cont.argsize() + frame::metadata_words_at_top;
608 assert(chunk_start_sp <= chunk->stack_size(), "sp not pointing into stack");
609
610 // increase max_size by what we're freezing minus the overlap
611 chunk->set_max_thawing_size(chunk->max_thawing_size() + cont_size() - _cont.argsize() - frame::metadata_words_at_top);
612
613 intptr_t* const bottom_sp = _cont_stack_bottom - _cont.argsize() - frame::metadata_words_at_top;
614 assert(bottom_sp == _bottom_address, "");
615 // Because the chunk isn't empty, we know there's a caller in the chunk, therefore the bottom-most frame
616 // should have a return barrier (installed back when we thawed it).
617 #ifdef ASSERT
618 {
619 intptr_t* retaddr_slot = (bottom_sp
620 - frame::sender_sp_ret_address_offset());
621 assert(ContinuationHelper::return_address_at(retaddr_slot)
622 == StubRoutines::cont_returnBarrier(),
623 "should be the continuation return barrier");
624 }
625 #endif
626 // We copy the fp from the chunk back to the stack because it contains some caller data,
627 // including, possibly, an oop that might have gone stale since we thawed.
628 patch_stack_pd(bottom_sp, chunk->sp_address());
629 // we don't patch the return pc at this time, so as not to make the stack unwalkable for async walks
630
631 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA false));
632 } else { // the chunk is empty
633 DEBUG_ONLY(_empty = true;)
634 const int chunk_start_sp = chunk->sp();
635
636 assert(chunk_start_sp == chunk->stack_size(), "");
637
638 chunk->set_max_thawing_size(cont_size());
639 chunk->set_argsize(_cont.argsize());
640
641 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA false));
642 }
643 }
644
645 bool FreezeBase::freeze_fast_new_chunk(stackChunkOop chunk) {
646 DEBUG_ONLY(_empty = true;)
647
648 // Install new chunk
649 _cont.set_tail(chunk);
650
651 if (UNLIKELY(chunk == nullptr || !_thread->cont_fastpath() || _barriers)) { // OOME/probably humongous
652 log_develop_trace(continuations)("Retrying slow. Barriers: %d", _barriers);
653 return false;
654 }
655
656 chunk->set_max_thawing_size(cont_size());
657 chunk->set_argsize(_cont.argsize());
658
659 // in a fresh chunk, we freeze *with* the bottom-most frame's stack arguments.
660 // They'll then be stored twice: in the chunk and in the parent chunk's top frame
661 const int chunk_start_sp = cont_size() + frame::metadata_words;
662 assert(chunk_start_sp == chunk->stack_size(), "");
663
664 DEBUG_ONLY(_orig_chunk_sp = chunk->start_address() + chunk_start_sp;)
665
666 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA true));
667
668 return true;
669 }
670
671 void FreezeBase::freeze_fast_copy(stackChunkOop chunk, int chunk_start_sp CONT_JFR_ONLY(COMMA bool chunk_is_allocated)) {
672 assert(chunk != nullptr, "");
673 assert(!chunk->has_mixed_frames(), "");
674 assert(!chunk->is_gc_mode(), "");
675 assert(!chunk->has_bitmap(), "");
676 assert(!chunk->requires_barriers(), "");
677 assert(chunk == _cont.tail(), "");
678
679 // We unwind frames after the last safepoint so that the GC will have found the oops in the frames, but before
680 // writing into the chunk. This is so that an asynchronous stack walk (not at a safepoint) that suspends us here
681 // will either see no continuation on the stack, or a consistent chunk.
682 unwind_frames();
683
684 log_develop_trace(continuations)("freeze_fast start: chunk " INTPTR_FORMAT " size: %d orig sp: %d argsize: %d",
685 p2i((oopDesc*)chunk), chunk->stack_size(), chunk_start_sp, _cont.argsize());
686 assert(chunk_start_sp <= chunk->stack_size(), "");
687 assert(chunk_start_sp >= cont_size(), "no room in the chunk");
688
689 const int chunk_new_sp = chunk_start_sp - cont_size(); // the chunk's new sp, after freeze
690 assert(!(_fast_freeze_size > 0) || _orig_chunk_sp - (chunk->start_address() + chunk_new_sp) == _fast_freeze_size, "");
691
692 intptr_t* chunk_top = chunk->start_address() + chunk_new_sp;
693 #ifdef ASSERT
694 if (!_empty) {
695 intptr_t* retaddr_slot = (_orig_chunk_sp
696 - frame::sender_sp_ret_address_offset());
697 assert(ContinuationHelper::return_address_at(retaddr_slot) == chunk->pc(),
698 "unexpected saved return address");
699 }
700 #endif
701
702 log_develop_trace(continuations)("freeze_fast start: " INTPTR_FORMAT " sp: %d chunk_top: " INTPTR_FORMAT,
703 p2i(chunk->start_address()), chunk_new_sp, p2i(chunk_top));
704 intptr_t* from = _cont_stack_top - frame::metadata_words_at_bottom;
705 intptr_t* to = chunk_top - frame::metadata_words_at_bottom;
706 copy_to_chunk(from, to, cont_size() + frame::metadata_words_at_bottom);
707 // Because we're not patched yet, the chunk is now in a bad state
708
709 // patch return pc of the bottom-most frozen frame (now in the chunk)
710 // with the actual caller's return address
711 intptr_t* chunk_bottom_retaddr_slot = (chunk_top + cont_size()
712 - _cont.argsize()
713 - frame::metadata_words_at_top
714 - frame::sender_sp_ret_address_offset());
715 #ifdef ASSERT
716 if (!_empty) {
717 assert(ContinuationHelper::return_address_at(chunk_bottom_retaddr_slot)
718 == StubRoutines::cont_returnBarrier(),
719 "should be the continuation return barrier");
720 }
721 #endif
722 ContinuationHelper::patch_return_address_at(chunk_bottom_retaddr_slot,
723 chunk->pc());
724
725 // We're always writing to a young chunk, so the GC can't see it until the next safepoint.
726 chunk->set_sp(chunk_new_sp);
727 // set chunk->pc to the return address of the topmost frame in the chunk
728 chunk->set_pc(ContinuationHelper::return_address_at(
729 _cont_stack_top - frame::sender_sp_ret_address_offset()));
730
731 _cont.write();
732
733 log_develop_trace(continuations)("FREEZE CHUNK #" INTPTR_FORMAT " (young)", _cont.hash());
734 LogTarget(Trace, continuations) lt;
735 if (lt.develop_is_enabled()) {
736 LogStream ls(lt);
737 chunk->print_on(true, &ls);
738 }
739
740 // Verification
741 assert(_cont.chunk_invariant(), "");
742 chunk->verify();
743
744 #if CONT_JFR
745 EventContinuationFreezeFast e;
746 if (e.should_commit()) {
747 e.set_id(cast_from_oop<u8>(chunk));
748 DEBUG_ONLY(e.set_allocate(chunk_is_allocated);)
749 e.set_size(cont_size() << LogBytesPerWord);
750 e.commit();
751 }
752 #endif
753 }
754
755 NOINLINE freeze_result FreezeBase::freeze_slow() {
756 #ifdef ASSERT
757 ResourceMark rm;
758 #endif
759
760 log_develop_trace(continuations)("freeze_slow #" INTPTR_FORMAT, _cont.hash());
761 assert(_thread->thread_state() == _thread_in_vm || _thread->thread_state() == _thread_blocked, "");
762
763 #if CONT_JFR
764 EventContinuationFreezeSlow e;
765 if (e.should_commit()) {
766 e.set_id(cast_from_oop<u8>(_cont.continuation()));
767 e.commit();
768 }
769 #endif
770
771 init_rest();
772
773 HandleMark hm(Thread::current());
774
775 frame f = freeze_start_frame();
776
777 LogTarget(Debug, continuations) lt;
778 if (lt.develop_is_enabled()) {
779 LogStream ls(lt);
780 f.print_on(&ls);
781 }
782
783 frame caller; // the frozen caller in the chunk
784 freeze_result res = recurse_freeze(f, caller, 0, false, true);
785
786 if (res == freeze_ok) {
787 finish_freeze(f, caller);
788 _cont.write();
789 }
790
791 return res;
792 }
793
794 frame FreezeBase::freeze_start_frame() {
795 frame f = _thread->last_frame();
796 if (LIKELY(!_preempt)) {
797 return freeze_start_frame_yield_stub(f);
798 } else {
799 return freeze_start_frame_safepoint_stub(f);
800 }
801 }
802
803 frame FreezeBase::freeze_start_frame_yield_stub(frame f) {
804 assert(SharedRuntime::cont_doYield_stub()->contains(f.pc()), "must be");
805 f = sender<ContinuationHelper::NonInterpretedUnknownFrame>(f);
806 assert(Continuation::is_frame_in_continuation(_thread->last_continuation(), f), "");
807 return f;
808 }
809
810 frame FreezeBase::freeze_start_frame_safepoint_stub(frame f) {
811 #if (defined(X86) || defined(AARCH64) || defined(RISCV64)) && !defined(ZERO)
812 f.set_fp(f.real_fp()); // f.set_fp(*Frame::callee_link_address(f)); // ????
813 #else
814 Unimplemented();
815 #endif
816 if (!Interpreter::contains(f.pc())) {
817 assert(ContinuationHelper::Frame::is_stub(f.cb()), "must be");
818 assert(f.oop_map() != nullptr, "must be");
819
820 if (Interpreter::contains(ContinuationHelper::StubFrame::return_pc(f))) {
821 f = sender<ContinuationHelper::StubFrame>(f); // Safepoint stub in interpreter
822 }
823 }
824 assert(Continuation::is_frame_in_continuation(_thread->last_continuation(), f), "");
825 return f;
826 }
827
828 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
829 NOINLINE freeze_result FreezeBase::recurse_freeze(frame& f, frame& caller, int callee_argsize, bool callee_interpreted, bool top) {
830 assert(f.unextended_sp() < _bottom_address, ""); // see recurse_freeze_java_frame
831 assert(f.is_interpreted_frame() || ((top && _preempt) == ContinuationHelper::Frame::is_stub(f.cb())), "");
832
833 if (stack_overflow()) {
834 return freeze_exception;
835 }
836
837 if (f.is_compiled_frame()) {
838 if (UNLIKELY(f.oop_map() == nullptr)) {
839 // special native frame
840 return freeze_pinned_native;
841 }
842 return recurse_freeze_compiled_frame(f, caller, callee_argsize, callee_interpreted);
843 } else if (f.is_interpreted_frame()) {
844 assert((_preempt && top) || !f.interpreter_frame_method()->is_native(), "");
845 if (_preempt && top && f.interpreter_frame_method()->is_native()) {
846 // int native entry
847 return freeze_pinned_native;
848 }
849
850 return recurse_freeze_interpreted_frame(f, caller, callee_argsize, callee_interpreted);
851 } else if (_preempt && top && ContinuationHelper::Frame::is_stub(f.cb())) {
852 return recurse_freeze_stub_frame(f, caller);
853 } else {
854 return freeze_pinned_native;
855 }
856 }
857
858 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
859 // See also StackChunkFrameStream<frame_kind>::frame_size()
860 template<typename FKind>
861 inline freeze_result FreezeBase::recurse_freeze_java_frame(const frame& f, frame& caller, int fsize, int argsize) {
862 assert(FKind::is_instance(f), "");
863
864 assert(fsize > 0, "");
865 assert(argsize >= 0, "");
866 _freeze_size += fsize;
867 NOT_PRODUCT(_frames++;)
868
869 assert(FKind::frame_bottom(f) <= _bottom_address, "");
870
871 // We don't use FKind::frame_bottom(f) == _bottom_address because on x64 there's sometimes an extra word between
872 // enterSpecial and an interpreted frame
873 if (FKind::frame_bottom(f) >= _bottom_address - 1) {
874 return finalize_freeze(f, caller, argsize); // recursion end
875 } else {
876 frame senderf = sender<FKind>(f);
877 assert(FKind::interpreted || senderf.sp() == senderf.unextended_sp(), "");
878 freeze_result result = recurse_freeze(senderf, caller, argsize, FKind::interpreted, false); // recursive call
879 return result;
880 }
881 }
882
883 inline void FreezeBase::before_freeze_java_frame(const frame& f, const frame& caller, int fsize, int argsize, bool is_bottom_frame) {
884 LogTarget(Trace, continuations) lt;
885 if (lt.develop_is_enabled()) {
886 LogStream ls(lt);
887 ls.print_cr("======== FREEZING FRAME interpreted: %d bottom: %d", f.is_interpreted_frame(), is_bottom_frame);
888 ls.print_cr("fsize: %d argsize: %d", fsize, argsize);
889 f.print_value_on(&ls, nullptr);
890 }
891 assert(caller.is_interpreted_frame() == Interpreter::contains(caller.pc()), "");
892 }
893
894 inline void FreezeBase::after_freeze_java_frame(const frame& hf, bool is_bottom_frame) {
895 LogTarget(Trace, continuations) lt;
896 if (lt.develop_is_enabled()) {
897 LogStream ls(lt);
898 DEBUG_ONLY(hf.print_value_on(&ls, nullptr);)
899 assert(hf.is_heap_frame(), "should be");
900 DEBUG_ONLY(print_frame_layout(hf, false, &ls);)
901 if (is_bottom_frame) {
902 ls.print_cr("bottom h-frame:");
903 hf.print_on(&ls);
904 }
905 }
906 }
907
908 // The parameter argsize_md includes metadata that has to be part of caller/callee overlap.
909 // See also StackChunkFrameStream<frame_kind>::frame_size()
910 freeze_result FreezeBase::finalize_freeze(const frame& callee, frame& caller, int argsize_md) {
911 int argsize = argsize_md - frame::metadata_words_at_top;
912 assert(callee.is_interpreted_frame()
913 || callee.cb()->as_nmethod()->is_osr_method()
914 || argsize == _cont.argsize(), "argsize: %d cont.argsize: %d", argsize, _cont.argsize());
915 log_develop_trace(continuations)("bottom: " INTPTR_FORMAT " count %d size: %d argsize: %d",
916 p2i(_bottom_address), _frames, _freeze_size << LogBytesPerWord, argsize);
917
918 LogTarget(Trace, continuations) lt;
919
920 #ifdef ASSERT
921 bool empty = _cont.is_empty();
922 log_develop_trace(continuations)("empty: %d", empty);
923 #endif
924
925 stackChunkOop chunk = _cont.tail();
926
927 assert(chunk == nullptr || (chunk->max_thawing_size() == 0) == chunk->is_empty(), "");
928
929 _freeze_size += frame::metadata_words; // for top frame's metadata
930
931 int overlap = 0; // the args overlap the caller -- if there is one in this chunk and is of the same kind
932 int unextended_sp = -1;
933 if (chunk != nullptr) {
934 unextended_sp = chunk->sp();
935 if (!chunk->is_empty()) {
936 StackChunkFrameStream<ChunkFrames::Mixed> last(chunk);
937 unextended_sp = chunk->to_offset(StackChunkFrameStream<ChunkFrames::Mixed>(chunk).unextended_sp());
938 bool top_interpreted = Interpreter::contains(chunk->pc());
939 if (callee.is_interpreted_frame() == top_interpreted) {
940 overlap = argsize_md;
941 }
942 }
943 }
944
945 log_develop_trace(continuations)("finalize _size: %d overlap: %d unextended_sp: %d", _freeze_size, overlap, unextended_sp);
946
947 _freeze_size -= overlap;
948 assert(_freeze_size >= 0, "");
949
950 assert(chunk == nullptr || chunk->is_empty()
951 || unextended_sp == chunk->to_offset(StackChunkFrameStream<ChunkFrames::Mixed>(chunk).unextended_sp()), "");
952 assert(chunk != nullptr || unextended_sp < _freeze_size, "");
953
954 // _barriers can be set to true by an allocation in freeze_fast, in which case the chunk is available
955 bool allocated_old_in_freeze_fast = _barriers;
956 assert(!allocated_old_in_freeze_fast || (unextended_sp >= _freeze_size && chunk->is_empty()),
957 "Chunk allocated in freeze_fast is of insufficient size "
958 "unextended_sp: %d size: %d is_empty: %d", unextended_sp, _freeze_size, chunk->is_empty());
959 assert(!allocated_old_in_freeze_fast || (!UseZGC && !UseG1GC), "Unexpected allocation");
960
961 DEBUG_ONLY(bool empty_chunk = true);
962 if (unextended_sp < _freeze_size || chunk->is_gc_mode() || (!allocated_old_in_freeze_fast && chunk->requires_barriers())) {
963 // ALLOCATE NEW CHUNK
964
965 if (lt.develop_is_enabled()) {
966 LogStream ls(lt);
967 if (chunk == nullptr) {
968 ls.print_cr("no chunk");
969 } else {
970 ls.print_cr("chunk barriers: %d _size: %d free size: %d",
971 chunk->requires_barriers(), _freeze_size, chunk->sp() - frame::metadata_words);
972 chunk->print_on(&ls);
973 }
974 }
975
976 _freeze_size += overlap; // we're allocating a new chunk, so no overlap
977 // overlap = 0;
978
979 chunk = allocate_chunk_slow(_freeze_size);
980 if (chunk == nullptr) {
981 return freeze_exception;
982 }
983
984 // Install new chunk
985 _cont.set_tail(chunk);
986
987 int sp = chunk->stack_size() - argsize_md;
988 chunk->set_sp(sp);
989 chunk->set_argsize(argsize);
990 assert(is_empty(chunk), "");
991 } else {
992 // REUSE EXISTING CHUNK
993 log_develop_trace(continuations)("Reusing chunk mixed: %d empty: %d", chunk->has_mixed_frames(), chunk->is_empty());
994 if (chunk->is_empty()) {
995 int sp = chunk->stack_size() - argsize_md;
996 chunk->set_sp(sp);
997 chunk->set_argsize(argsize);
998 _freeze_size += overlap;
999 assert(chunk->max_thawing_size() == 0, "");
1000 } DEBUG_ONLY(else empty_chunk = false;)
1001 }
1002 assert(!chunk->is_gc_mode(), "");
1003 assert(!chunk->has_bitmap(), "");
1004 chunk->set_has_mixed_frames(true);
1005
1006 assert(chunk->requires_barriers() == _barriers, "");
1007 assert(!_barriers || is_empty(chunk), "");
1008
1009 assert(!is_empty(chunk) || StackChunkFrameStream<ChunkFrames::Mixed>(chunk).is_done(), "");
1010 assert(!is_empty(chunk) || StackChunkFrameStream<ChunkFrames::Mixed>(chunk).to_frame().is_empty(), "");
1011
1012 // We unwind frames after the last safepoint so that the GC will have found the oops in the frames, but before
1013 // writing into the chunk. This is so that an asynchronous stack walk (not at a safepoint) that suspends us here
1014 // will either see no continuation or a consistent chunk.
1015 unwind_frames();
1016
1017 chunk->set_max_thawing_size(chunk->max_thawing_size() + _freeze_size - frame::metadata_words);
1018
1019 if (lt.develop_is_enabled()) {
1020 LogStream ls(lt);
1021 ls.print_cr("top chunk:");
1022 chunk->print_on(&ls);
1023 }
1024
1025 // The topmost existing frame in the chunk; or an empty frame if the chunk is empty
1026 caller = StackChunkFrameStream<ChunkFrames::Mixed>(chunk).to_frame();
1027
1028 DEBUG_ONLY(_last_write = caller.unextended_sp() + (empty_chunk ? argsize_md : overlap);)
1029
1030 assert(chunk->is_in_chunk(_last_write - _freeze_size),
1031 "last_write-size: " INTPTR_FORMAT " start: " INTPTR_FORMAT, p2i(_last_write-_freeze_size), p2i(chunk->start_address()));
1032 #ifdef ASSERT
1033 if (lt.develop_is_enabled()) {
1034 LogStream ls(lt);
1035 ls.print_cr("top hframe before (freeze):");
1036 assert(caller.is_heap_frame(), "should be");
1037 caller.print_on(&ls);
1038 }
1039
1040 assert(!empty || Continuation::is_continuation_entry_frame(callee, nullptr), "");
1041
1042 frame entry = sender(callee);
1043
1044 assert(Continuation::is_return_barrier_entry(entry.pc()) || Continuation::is_continuation_enterSpecial(entry), "");
1045 assert(callee.is_interpreted_frame() || entry.sp() == entry.unextended_sp(), "");
1046 #endif
1047
1048 return freeze_ok_bottom;
1049 }
1050
1051 void FreezeBase::patch(const frame& f, frame& hf, const frame& caller, bool is_bottom_frame) {
1052 if (is_bottom_frame) {
1053 // If we're the bottom frame, we need to replace the return barrier with the real
1054 // caller's pc.
1055 address last_pc = caller.pc();
1056 assert((last_pc == nullptr) == is_empty(_cont.tail()), "");
1057 ContinuationHelper::Frame::patch_pc(caller, last_pc);
1058 } else {
1059 assert(!caller.is_empty(), "");
1060 }
1061
1062 patch_pd(hf, caller);
1063
1064 if (f.is_interpreted_frame()) {
1065 assert(hf.is_heap_frame(), "should be");
1066 ContinuationHelper::InterpretedFrame::patch_sender_sp(hf, caller);
1067 }
1068
1069 #ifdef ASSERT
1070 if (hf.is_compiled_frame()) {
1071 if (f.is_deoptimized_frame()) { // TODO DEOPT: long term solution: unroll on freeze and patch pc
1072 log_develop_trace(continuations)("Freezing deoptimized frame");
1073 assert(f.cb()->as_nmethod()->is_deopt_pc(f.raw_pc()), "");
1074 assert(f.cb()->as_nmethod()->is_deopt_pc(ContinuationHelper::Frame::real_pc(f)), "");
1075 }
1076 }
1077 #endif
1078 }
1079
1080 #ifdef ASSERT
1081 static void verify_frame_top(const frame& f, intptr_t* top) {
1082 ResourceMark rm;
1083 InterpreterOopMap mask;
1084 f.interpreted_frame_oop_map(&mask);
1085 assert(top <= ContinuationHelper::InterpretedFrame::frame_top(f, &mask),
1086 "frame_top: " INTPTR_FORMAT " Interpreted::frame_top: " INTPTR_FORMAT,
1087 p2i(top), p2i(ContinuationHelper::InterpretedFrame::frame_top(f, &mask)));
1088 }
1089 #endif // ASSERT
1090
1091 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
1092 // See also StackChunkFrameStream<frame_kind>::frame_size()
1093 NOINLINE freeze_result FreezeBase::recurse_freeze_interpreted_frame(frame& f, frame& caller,
1094 int callee_argsize /* incl. metadata */,
1095 bool callee_interpreted) {
1096 adjust_interpreted_frame_unextended_sp(f);
1097
1098 // The frame's top never includes the stack arguments to the callee
1099 intptr_t* const stack_frame_top = ContinuationHelper::InterpretedFrame::frame_top(f, callee_argsize, callee_interpreted);
1100 intptr_t* const stack_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(f);
1101 const int fsize = pointer_delta_as_int(stack_frame_bottom, stack_frame_top);
1102
1103 DEBUG_ONLY(verify_frame_top(f, stack_frame_top));
1104
1105 Method* frame_method = ContinuationHelper::Frame::frame_method(f);
1106 // including metadata between f and its args
1107 const int argsize = ContinuationHelper::InterpretedFrame::stack_argsize(f) + frame::metadata_words_at_top;
1108
1109 log_develop_trace(continuations)("recurse_freeze_interpreted_frame %s _size: %d fsize: %d argsize: %d",
1110 frame_method->name_and_sig_as_C_string(), _freeze_size, fsize, argsize);
1111 // we'd rather not yield inside methods annotated with @JvmtiMountTransition
1112 assert(!ContinuationHelper::Frame::frame_method(f)->jvmti_mount_transition(), "");
1113
1114 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::InterpretedFrame>(f, caller, fsize, argsize);
1115 if (UNLIKELY(result > freeze_ok_bottom)) {
1116 return result;
1117 }
1118
1119 bool is_bottom_frame = result == freeze_ok_bottom;
1120 assert(!caller.is_empty() || is_bottom_frame, "");
1121
1122 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, 0, is_bottom_frame);)
1123
1124 frame hf = new_heap_frame<ContinuationHelper::InterpretedFrame>(f, caller);
1125 _total_align_size += frame::align_wiggle; // add alignment room for internal interpreted frame alignment on AArch64/PPC64
1126
1127 intptr_t* heap_frame_top = ContinuationHelper::InterpretedFrame::frame_top(hf, callee_argsize, callee_interpreted);
1128 intptr_t* heap_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(hf);
1129 assert(heap_frame_bottom == heap_frame_top + fsize, "");
1130
1131 // Some architectures (like AArch64/PPC64/RISC-V) add padding between the locals and the fixed_frame to keep the fp 16-byte-aligned.
1132 // On those architectures we freeze the padding in order to keep the same fp-relative offsets in the fixed_frame.
1133 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1134 assert(!is_bottom_frame || !caller.is_interpreted_frame() || (heap_frame_top + fsize) == (caller.unextended_sp() + argsize), "");
1135
1136 relativize_interpreted_frame_metadata(f, hf);
1137
1138 patch(f, hf, caller, is_bottom_frame);
1139
1140 CONT_JFR_ONLY(_jfr_info.record_interpreted_frame();)
1141 DEBUG_ONLY(after_freeze_java_frame(hf, is_bottom_frame);)
1142 caller = hf;
1143
1144 // Mark frame_method's GC epoch for class redefinition on_stack calculation.
1145 frame_method->record_gc_epoch();
1146
1147 return freeze_ok;
1148 }
1149
1150 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
1151 // See also StackChunkFrameStream<frame_kind>::frame_size()
1152 freeze_result FreezeBase::recurse_freeze_compiled_frame(frame& f, frame& caller,
1153 int callee_argsize /* incl. metadata */,
1154 bool callee_interpreted) {
1155 // The frame's top never includes the stack arguments to the callee
1156 intptr_t* const stack_frame_top = ContinuationHelper::CompiledFrame::frame_top(f, callee_argsize, callee_interpreted);
1157 intptr_t* const stack_frame_bottom = ContinuationHelper::CompiledFrame::frame_bottom(f);
1158 // including metadata between f and its stackargs
1159 const int argsize = ContinuationHelper::CompiledFrame::stack_argsize(f) + frame::metadata_words_at_top;
1160 const int fsize = pointer_delta_as_int(stack_frame_bottom + argsize, stack_frame_top);
1161
1162 log_develop_trace(continuations)("recurse_freeze_compiled_frame %s _size: %d fsize: %d argsize: %d",
1163 ContinuationHelper::Frame::frame_method(f) != nullptr ?
1164 ContinuationHelper::Frame::frame_method(f)->name_and_sig_as_C_string() : "",
1165 _freeze_size, fsize, argsize);
1166 // we'd rather not yield inside methods annotated with @JvmtiMountTransition
1167 assert(!ContinuationHelper::Frame::frame_method(f)->jvmti_mount_transition(), "");
1168
1169 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::CompiledFrame>(f, caller, fsize, argsize);
1170 if (UNLIKELY(result > freeze_ok_bottom)) {
1171 return result;
1172 }
1173
1174 bool is_bottom_frame = result == freeze_ok_bottom;
1175 assert(!caller.is_empty() || is_bottom_frame, "");
1176
1177 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, argsize, is_bottom_frame);)
1178
1179 frame hf = new_heap_frame<ContinuationHelper::CompiledFrame>(f, caller);
1180
1181 intptr_t* heap_frame_top = ContinuationHelper::CompiledFrame::frame_top(hf, callee_argsize, callee_interpreted);
1182
1183 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1184 assert(!is_bottom_frame || !caller.is_compiled_frame() || (heap_frame_top + fsize) == (caller.unextended_sp() + argsize), "");
1185
1186 if (caller.is_interpreted_frame()) {
1187 _total_align_size += frame::align_wiggle; // See Thaw::align
1188 }
1189
1190 patch(f, hf, caller, is_bottom_frame);
1191
1192 assert(is_bottom_frame || Interpreter::contains(ContinuationHelper::CompiledFrame::real_pc(caller)) == caller.is_interpreted_frame(), "");
1193
1194 DEBUG_ONLY(after_freeze_java_frame(hf, is_bottom_frame);)
1195 caller = hf;
1196 return freeze_ok;
1197 }
1198
1199 NOINLINE freeze_result FreezeBase::recurse_freeze_stub_frame(frame& f, frame& caller) {
1200 intptr_t* const stack_frame_top = ContinuationHelper::StubFrame::frame_top(f, 0, 0);
1201 const int fsize = f.cb()->frame_size();
1202
1203 log_develop_trace(continuations)("recurse_freeze_stub_frame %s _size: %d fsize: %d :: " INTPTR_FORMAT " - " INTPTR_FORMAT,
1204 f.cb()->name(), _freeze_size, fsize, p2i(stack_frame_top), p2i(stack_frame_top+fsize));
1205
1206 // recurse_freeze_java_frame and freeze inlined here because we need to use a full RegisterMap for lock ownership
1207 NOT_PRODUCT(_frames++;)
1208 _freeze_size += fsize;
1209
1210 RegisterMap map(_cont.thread(),
1211 RegisterMap::UpdateMap::include,
1212 RegisterMap::ProcessFrames::skip,
1213 RegisterMap::WalkContinuation::skip);
1214 map.set_include_argument_oops(false);
1215 ContinuationHelper::update_register_map<ContinuationHelper::StubFrame>(f, &map);
1216 f.oop_map()->update_register_map(&f, &map); // we have callee-save registers in this case
1217 frame senderf = sender<ContinuationHelper::StubFrame>(f);
1218 assert(senderf.unextended_sp() < _bottom_address - 1, "");
1219 assert(senderf.is_compiled_frame(), "");
1220
1221 if (UNLIKELY(senderf.oop_map() == nullptr)) {
1222 // native frame
1223 return freeze_pinned_native;
1224 }
1225
1226 freeze_result result = recurse_freeze_compiled_frame(senderf, caller, 0, 0); // This might be deoptimized
1227 if (UNLIKELY(result > freeze_ok_bottom)) {
1228 return result;
1229 }
1230 assert(result != freeze_ok_bottom, "");
1231 assert(!caller.is_interpreted_frame(), "");
1232
1233 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, 0, false);)
1234 frame hf = new_heap_frame<ContinuationHelper::StubFrame>(f, caller);
1235 intptr_t* heap_frame_top = ContinuationHelper::StubFrame::frame_top(hf, 0, 0);
1236 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1237 DEBUG_ONLY(after_freeze_java_frame(hf, false);)
1238
1239 caller = hf;
1240 return freeze_ok;
1241 }
1242
1243 NOINLINE void FreezeBase::finish_freeze(const frame& f, const frame& top) {
1244 stackChunkOop chunk = _cont.tail();
1245
1246 LogTarget(Trace, continuations) lt;
1247 if (lt.develop_is_enabled()) {
1248 LogStream ls(lt);
1249 assert(top.is_heap_frame(), "should be");
1250 top.print_on(&ls);
1251 }
1252
1253 set_top_frame_metadata_pd(top);
1254
1255 chunk->set_sp(chunk->to_offset(top.sp()));
1256 chunk->set_pc(top.pc());
1257
1258 chunk->set_max_thawing_size(chunk->max_thawing_size() + _total_align_size);
1259
1260 // At this point the chunk is consistent
1261
1262 if (UNLIKELY(_barriers)) {
1263 log_develop_trace(continuations)("do barriers on old chunk");
1264 // Serial and Parallel GC can allocate objects directly into the old generation.
1265 // Then we want to relativize the derived pointers eagerly so that
1266 // old chunks are all in GC mode.
1267 assert(!UseG1GC, "G1 can not deal with allocating outside of eden");
1268 assert(!UseZGC, "ZGC can not deal with allocating chunks visible to marking");
1269 if (UseShenandoahGC) {
1270 _cont.tail()->relativize_derived_pointers_concurrently();
1271 } else {
1272 ContinuationGCSupport::transform_stack_chunk(_cont.tail());
1273 }
1274 // For objects in the old generation we must maintain the remembered set
1275 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>();
1276 }
1277
1278 log_develop_trace(continuations)("finish_freeze: has_mixed_frames: %d", chunk->has_mixed_frames());
1279 if (lt.develop_is_enabled()) {
1280 LogStream ls(lt);
1281 chunk->print_on(true, &ls);
1282 }
1283
1284 if (lt.develop_is_enabled()) {
1285 LogStream ls(lt);
1286 ls.print_cr("top hframe after (freeze):");
1287 assert(_cont.last_frame().is_heap_frame(), "should be");
1288 _cont.last_frame().print_on(&ls);
1289 }
1290
1291 assert(_cont.chunk_invariant(), "");
1292 }
1293
1294 inline bool FreezeBase::stack_overflow() { // detect stack overflow in recursive native code
1295 JavaThread* t = !_preempt ? _thread : JavaThread::current();
1296 assert(t == JavaThread::current(), "");
1297 if (os::current_stack_pointer() < t->stack_overflow_state()->shadow_zone_safe_limit()) {
1298 if (!_preempt) {
1299 ContinuationWrapper::SafepointOp so(t, _cont); // could also call _cont.done() instead
1300 Exceptions::_throw_msg(t, __FILE__, __LINE__, vmSymbols::java_lang_StackOverflowError(), "Stack overflow while freezing");
1301 }
1302 return true;
1303 }
1304 return false;
1305 }
1306
1307 class StackChunkAllocator : public MemAllocator {
1308 const size_t _stack_size;
1309 ContinuationWrapper& _continuation_wrapper;
1310 JvmtiSampledObjectAllocEventCollector* const _jvmti_event_collector;
1311 mutable bool _took_slow_path;
1312
1313 // Does the minimal amount of initialization needed for a TLAB allocation.
1314 // We don't need to do a full initialization, as such an allocation need not be immediately walkable.
1315 virtual oop initialize(HeapWord* mem) const override {
1316 assert(_stack_size > 0, "");
1317 assert(_stack_size <= max_jint, "");
1318 assert(_word_size > _stack_size, "");
1319
1320 // zero out fields (but not the stack)
1321 const size_t hs = oopDesc::header_size();
1322 Copy::fill_to_aligned_words(mem + hs, vmClasses::StackChunk_klass()->size_helper() - hs);
1323
1324 jdk_internal_vm_StackChunk::set_size(mem, (int)_stack_size);
1325 jdk_internal_vm_StackChunk::set_sp(mem, (int)_stack_size);
1326
1327 return finish(mem);
1328 }
1329
1330 stackChunkOop allocate_fast() const {
1331 if (!UseTLAB) {
1332 return nullptr;
1333 }
1334
1335 HeapWord* const mem = MemAllocator::mem_allocate_inside_tlab_fast();
1336 if (mem == nullptr) {
1337 return nullptr;
1338 }
1339
1340 oop obj = initialize(mem);
1341 return stackChunkOopDesc::cast(obj);
1342 }
1343
1344 public:
1345 StackChunkAllocator(Klass* klass,
1346 size_t word_size,
1347 Thread* thread,
1348 size_t stack_size,
1349 ContinuationWrapper& continuation_wrapper,
1350 JvmtiSampledObjectAllocEventCollector* jvmti_event_collector)
1351 : MemAllocator(klass, word_size, thread),
1352 _stack_size(stack_size),
1353 _continuation_wrapper(continuation_wrapper),
1354 _jvmti_event_collector(jvmti_event_collector),
1355 _took_slow_path(false) {}
1356
1357 // Provides it's own, specialized allocation which skips instrumentation
1358 // if the memory can be allocated without going to a slow-path.
1359 stackChunkOop allocate() const {
1360 // First try to allocate without any slow-paths or instrumentation.
1361 stackChunkOop obj = allocate_fast();
1362 if (obj != nullptr) {
1363 return obj;
1364 }
1365
1366 // Now try full-blown allocation with all expensive operations,
1367 // including potentially safepoint operations.
1368 _took_slow_path = true;
1369
1370 // Protect unhandled Loom oops
1371 ContinuationWrapper::SafepointOp so(_thread, _continuation_wrapper);
1372
1373 // Can safepoint
1374 _jvmti_event_collector->start();
1375
1376 // Can safepoint
1377 return stackChunkOopDesc::cast(MemAllocator::allocate());
1378 }
1379
1380 bool took_slow_path() const {
1381 return _took_slow_path;
1382 }
1383 };
1384
1385 template <typename ConfigT>
1386 stackChunkOop Freeze<ConfigT>::allocate_chunk(size_t stack_size) {
1387 log_develop_trace(continuations)("allocate_chunk allocating new chunk");
1388
1389 InstanceStackChunkKlass* klass = InstanceStackChunkKlass::cast(vmClasses::StackChunk_klass());
1390 size_t size_in_words = klass->instance_size(stack_size);
1391
1392 if (CollectedHeap::stack_chunk_max_size() > 0 && size_in_words >= CollectedHeap::stack_chunk_max_size()) {
1393 if (!_preempt) {
1394 throw_stack_overflow_on_humongous_chunk();
1395 }
1396 return nullptr;
1397 }
1398
1399 JavaThread* current = _preempt ? JavaThread::current() : _thread;
1400 assert(current == JavaThread::current(), "should be current");
1401
1402 // Allocate the chunk.
1403 //
1404 // This might safepoint while allocating, but all safepointing due to
1405 // instrumentation have been deferred. This property is important for
1406 // some GCs, as this ensures that the allocated object is in the young
1407 // generation / newly allocated memory.
1408 StackChunkAllocator allocator(klass, size_in_words, current, stack_size, _cont, _jvmti_event_collector);
1409 stackChunkOop chunk = allocator.allocate();
1410
1411 if (chunk == nullptr) {
1412 return nullptr; // OOME
1413 }
1414
1415 // assert that chunk is properly initialized
1416 assert(chunk->stack_size() == (int)stack_size, "");
1417 assert(chunk->size() >= stack_size, "chunk->size(): %zu size: %zu", chunk->size(), stack_size);
1418 assert(chunk->sp() == chunk->stack_size(), "");
1419 assert((intptr_t)chunk->start_address() % 8 == 0, "");
1420 assert(chunk->max_thawing_size() == 0, "");
1421 assert(chunk->pc() == nullptr, "");
1422 assert(chunk->argsize() == 0, "");
1423 assert(chunk->flags() == 0, "");
1424 assert(chunk->is_gc_mode() == false, "");
1425
1426 // fields are uninitialized
1427 chunk->set_parent_access<IS_DEST_UNINITIALIZED>(_cont.last_nonempty_chunk());
1428 chunk->set_cont_access<IS_DEST_UNINITIALIZED>(_cont.continuation());
1429
1430 #if INCLUDE_ZGC
1431 if (UseZGC) {
1432 if (ZGenerational) {
1433 ZStackChunkGCData::initialize(chunk);
1434 }
1435 assert(!chunk->requires_barriers(), "ZGC always allocates in the young generation");
1436 _barriers = false;
1437 } else
1438 #endif
1439 #if INCLUDE_SHENANDOAHGC
1440 if (UseShenandoahGC) {
1441 _barriers = chunk->requires_barriers();
1442 } else
1443 #endif
1444 {
1445 if (!allocator.took_slow_path()) {
1446 // Guaranteed to be in young gen / newly allocated memory
1447 assert(!chunk->requires_barriers(), "Unfamiliar GC requires barriers on TLAB allocation");
1448 _barriers = false;
1449 } else {
1450 // Some GCs could put direct allocations in old gen for slow-path
1451 // allocations; need to explicitly check if that was the case.
1452 _barriers = chunk->requires_barriers();
1453 }
1454 }
1455
1456 if (_barriers) {
1457 log_develop_trace(continuations)("allocation requires barriers");
1458 }
1459
1460 assert(chunk->parent() == nullptr || chunk->parent()->is_stackChunk(), "");
1461
1462 return chunk;
1463 }
1464
1465 void FreezeBase::throw_stack_overflow_on_humongous_chunk() {
1466 ContinuationWrapper::SafepointOp so(_thread, _cont); // could also call _cont.done() instead
1467 Exceptions::_throw_msg(_thread, __FILE__, __LINE__, vmSymbols::java_lang_StackOverflowError(), "Humongous stack chunk");
1468 }
1469
1470 #if INCLUDE_JVMTI
1471 static int num_java_frames(ContinuationWrapper& cont) {
1472 ResourceMark rm; // used for scope traversal in num_java_frames(nmethod*, address)
1473 int count = 0;
1474 for (stackChunkOop chunk = cont.tail(); chunk != nullptr; chunk = chunk->parent()) {
1475 count += chunk->num_java_frames();
1476 }
1477 return count;
1478 }
1479
1480 static void invalidate_jvmti_stack(JavaThread* thread) {
1481 if (thread->is_interp_only_mode()) {
1482 JvmtiThreadState *state = thread->jvmti_thread_state();
1483 if (state != nullptr)
1484 state->invalidate_cur_stack_depth();
1485 }
1486 }
1487
1488 static void jvmti_yield_cleanup(JavaThread* thread, ContinuationWrapper& cont) {
1489 if (JvmtiExport::can_post_frame_pop()) {
1490 int num_frames = num_java_frames(cont);
1491
1492 ContinuationWrapper::SafepointOp so(Thread::current(), cont);
1493 JvmtiExport::continuation_yield_cleanup(JavaThread::current(), num_frames);
1494 }
1495 invalidate_jvmti_stack(thread);
1496 }
1497 #endif // INCLUDE_JVMTI
1498
1499 #ifdef ASSERT
1500 static bool monitors_on_stack(JavaThread* thread) {
1501 ContinuationEntry* ce = thread->last_continuation();
1502 RegisterMap map(thread,
1503 RegisterMap::UpdateMap::include,
1504 RegisterMap::ProcessFrames::include,
1505 RegisterMap::WalkContinuation::skip);
1506 map.set_include_argument_oops(false);
1507 for (frame f = thread->last_frame(); Continuation::is_frame_in_continuation(ce, f); f = f.sender(&map)) {
1508 if ((f.is_interpreted_frame() && ContinuationHelper::InterpretedFrame::is_owning_locks(f)) ||
1509 (f.is_compiled_frame() && ContinuationHelper::CompiledFrame::is_owning_locks(map.thread(), &map, f))) {
1510 return true;
1511 }
1512 }
1513 return false;
1514 }
1515
1516 // There are no interpreted frames if we're not called from the interpreter and we haven't ancountered an i2c
1517 // adapter or called Deoptimization::unpack_frames. As for native frames, upcalls from JNI also go through the
1518 // interpreter (see JavaCalls::call_helper), while the UpcallLinker explicitly sets cont_fastpath.
1519 bool FreezeBase::check_valid_fast_path() {
1520 ContinuationEntry* ce = _thread->last_continuation();
1521 RegisterMap map(_thread,
1522 RegisterMap::UpdateMap::skip,
1523 RegisterMap::ProcessFrames::skip,
1524 RegisterMap::WalkContinuation::skip);
1525 map.set_include_argument_oops(false);
1526 for (frame f = freeze_start_frame(); Continuation::is_frame_in_continuation(ce, f); f = f.sender(&map)) {
1527 if (!f.is_compiled_frame() || f.is_deoptimized_frame()) {
1528 return false;
1529 }
1530 }
1531 return true;
1532 }
1533 #endif // ASSERT
1534
1535 static inline int freeze_epilog(JavaThread* thread, ContinuationWrapper& cont) {
1536 verify_continuation(cont.continuation());
1537 assert(!cont.is_empty(), "");
1538 // This is done for the sake of the enterSpecial frame
1539 StackWatermarkSet::after_unwind(thread);
1540
1541 log_develop_debug(continuations)("=== End of freeze cont ### #" INTPTR_FORMAT, cont.hash());
1542
1543 return 0;
1544 }
1545
1546 static int freeze_epilog(JavaThread* thread, ContinuationWrapper& cont, freeze_result res) {
1547 if (UNLIKELY(res != freeze_ok)) {
1548 verify_continuation(cont.continuation());
1549 log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1550 return res;
1551 }
1552
1553 JVMTI_ONLY(jvmti_yield_cleanup(thread, cont)); // can safepoint
1554 return freeze_epilog(thread, cont);
1555 }
1556
1557 template<typename ConfigT>
1558 static inline int freeze_internal(JavaThread* current, intptr_t* const sp) {
1559 assert(!current->has_pending_exception(), "");
1560
1561 #ifdef ASSERT
1562 log_trace(continuations)("~~~~ freeze sp: " INTPTR_FORMAT, p2i(current->last_continuation()->entry_sp()));
1563 log_frames(current);
1564 #endif
1565
1566 CONT_JFR_ONLY(EventContinuationFreeze event;)
1567
1568 ContinuationEntry* entry = current->last_continuation();
1569
1570 oop oopCont = entry->cont_oop(current);
1571 assert(oopCont == current->last_continuation()->cont_oop(current), "");
1572 assert(ContinuationEntry::assert_entry_frame_laid_out(current), "");
1573
1574 verify_continuation(oopCont);
1575 ContinuationWrapper cont(current, oopCont);
1576 log_develop_debug(continuations)("FREEZE #" INTPTR_FORMAT " " INTPTR_FORMAT, cont.hash(), p2i((oopDesc*)oopCont));
1577
1578 assert(entry->is_virtual_thread() == (entry->scope(current) == java_lang_VirtualThread::vthread_scope()), "");
1579
1580 assert(monitors_on_stack(current) == ((current->held_monitor_count() - current->jni_monitor_count()) > 0),
1581 "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());
1582
1583 if (entry->is_pinned() || current->held_monitor_count() > 0) {
1584 log_develop_debug(continuations)("PINNED due to critical section/hold monitor");
1585 verify_continuation(cont.continuation());
1586 freeze_result res = entry->is_pinned() ? freeze_pinned_cs : freeze_pinned_monitor;
1587 log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1588 return res;
1589 }
1590
1591 Freeze<ConfigT> freeze(current, cont, sp);
1592
1593 assert(!current->cont_fastpath() || freeze.check_valid_fast_path(), "");
1594 bool fast = UseContinuationFastPath && current->cont_fastpath();
1595 if (fast && freeze.size_if_fast_freeze_available() > 0) {
1596 freeze.freeze_fast_existing_chunk();
1597 CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1598 freeze_epilog(current, cont);
1599 return 0;
1600 }
1601
1602 log_develop_trace(continuations)("chunk unavailable; transitioning to VM");
1603 assert(current == JavaThread::current(), "must be current thread except for preempt");
1604 JRT_BLOCK
1605 // delays a possible JvmtiSampledObjectAllocEventCollector in alloc_chunk
1606 JvmtiSampledObjectAllocEventCollector jsoaec(false);
1607 freeze.set_jvmti_event_collector(&jsoaec);
1608
1609 freeze_result res = fast ? freeze.try_freeze_fast() : freeze.freeze_slow();
1610
1611 CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1612 freeze_epilog(current, cont, res);
1613 cont.done(); // allow safepoint in the transition back to Java
1614 return res;
1615 JRT_BLOCK_END
1616 }
1617
1618 static freeze_result is_pinned0(JavaThread* thread, oop cont_scope, bool safepoint) {
1619 ContinuationEntry* entry = thread->last_continuation();
1620 if (entry == nullptr) {
1621 return freeze_ok;
1622 }
1623 if (entry->is_pinned()) {
1624 return freeze_pinned_cs;
1625 } else if (thread->held_monitor_count() > 0) {
1626 return freeze_pinned_monitor;
1627 }
1628
1629 RegisterMap map(thread,
1630 RegisterMap::UpdateMap::include,
1631 RegisterMap::ProcessFrames::skip,
1632 RegisterMap::WalkContinuation::skip);
1633 map.set_include_argument_oops(false);
1634 frame f = thread->last_frame();
1635
1636 if (!safepoint) {
1637 f = f.sender(&map); // this is the yield frame
1638 } else { // safepoint yield
1639 #if (defined(X86) || defined(AARCH64) || defined(RISCV64)) && !defined(ZERO)
1640 f.set_fp(f.real_fp()); // Instead of this, maybe in ContinuationWrapper::set_last_frame always use the real_fp?
1641 #else
1642 Unimplemented();
1643 #endif
1644 if (!Interpreter::contains(f.pc())) {
1645 assert(ContinuationHelper::Frame::is_stub(f.cb()), "must be");
1646 assert(f.oop_map() != nullptr, "must be");
1647 f.oop_map()->update_register_map(&f, &map); // we have callee-save registers in this case
1648 }
1649 }
1650
1651 while (true) {
1652 if ((f.is_interpreted_frame() && f.interpreter_frame_method()->is_native()) || f.is_native_frame()) {
1653 return freeze_pinned_native;
1654 }
1655
1656 f = f.sender(&map);
1657 if (!Continuation::is_frame_in_continuation(entry, f)) {
1658 oop scope = jdk_internal_vm_Continuation::scope(entry->cont_oop(thread));
1659 if (scope == cont_scope) {
1660 break;
1661 }
1662 intx monitor_count = entry->parent_held_monitor_count();
1663 entry = entry->parent();
1664 if (entry == nullptr) {
1665 break;
1666 }
1667 if (entry->is_pinned()) {
1668 return freeze_pinned_cs;
1669 } else if (monitor_count > 0) {
1670 return freeze_pinned_monitor;
1671 }
1672 }
1673 }
1674 return freeze_ok;
1675 }
1676
1677 /////////////// THAW ////
1678
1679 static int thaw_size(stackChunkOop chunk) {
1680 int size = chunk->max_thawing_size();
1681 size += frame::metadata_words; // For the top pc+fp in push_return_frame or top = stack_sp - frame::metadata_words in thaw_fast
1682 size += 2*frame::align_wiggle; // in case of alignments at the top and bottom
1683 return size;
1684 }
1685
1686 // make room on the stack for thaw
1687 // returns the size in bytes, or 0 on failure
1688 static inline int prepare_thaw_internal(JavaThread* thread, bool return_barrier) {
1689 log_develop_trace(continuations)("~~~~ prepare_thaw return_barrier: %d", return_barrier);
1690
1691 assert(thread == JavaThread::current(), "");
1692
1693 ContinuationEntry* ce = thread->last_continuation();
1694 assert(ce != nullptr, "");
1695 oop continuation = ce->cont_oop(thread);
1696 assert(continuation == get_continuation(thread), "");
1697 verify_continuation(continuation);
1698
1699 stackChunkOop chunk = jdk_internal_vm_Continuation::tail(continuation);
1700 assert(chunk != nullptr, "");
1701
1702 // The tail can be empty because it might still be available for another freeze.
1703 // However, here we want to thaw, so we get rid of it (it will be GCed).
1704 if (UNLIKELY(chunk->is_empty())) {
1705 chunk = chunk->parent();
1706 assert(chunk != nullptr, "");
1707 assert(!chunk->is_empty(), "");
1708 jdk_internal_vm_Continuation::set_tail(continuation, chunk);
1709 }
1710
1711 // Verification
1712 chunk->verify();
1713 assert(chunk->max_thawing_size() > 0, "chunk invariant violated; expected to not be empty");
1714
1715 // Only make space for the last chunk because we only thaw from the last chunk
1716 int size = thaw_size(chunk) << LogBytesPerWord;
1717
1718 const address bottom = (address)thread->last_continuation()->entry_sp();
1719 // 300 is an estimate for stack size taken for this native code, in addition to StackShadowPages
1720 // for the Java frames in the check below.
1721 if (!stack_overflow_check(thread, size + 300, bottom)) {
1722 return 0;
1723 }
1724
1725 log_develop_trace(continuations)("prepare_thaw bottom: " INTPTR_FORMAT " top: " INTPTR_FORMAT " size: %d",
1726 p2i(bottom), p2i(bottom - size), size);
1727 return size;
1728 }
1729
1730 class ThawBase : public StackObj {
1731 protected:
1732 JavaThread* _thread;
1733 ContinuationWrapper& _cont;
1734 CONT_JFR_ONLY(FreezeThawJfrInfo _jfr_info;)
1735
1736 intptr_t* _fastpath;
1737 bool _barriers;
1738 intptr_t* _top_unextended_sp_before_thaw;
1739 int _align_size;
1740 DEBUG_ONLY(intptr_t* _top_stack_address);
1741
1742 StackChunkFrameStream<ChunkFrames::Mixed> _stream;
1743
1744 NOT_PRODUCT(int _frames;)
1745
1746 protected:
1747 ThawBase(JavaThread* thread, ContinuationWrapper& cont) :
1748 _thread(thread), _cont(cont),
1749 _fastpath(nullptr) {
1750 DEBUG_ONLY(_top_unextended_sp_before_thaw = nullptr;)
1751 assert (cont.tail() != nullptr, "no last chunk");
1752 DEBUG_ONLY(_top_stack_address = _cont.entrySP() - thaw_size(cont.tail());)
1753 }
1754
1755 void clear_chunk(stackChunkOop chunk);
1756 int remove_top_compiled_frame_from_chunk(stackChunkOop chunk, int &argsize);
1757 void copy_from_chunk(intptr_t* from, intptr_t* to, int size);
1758
1759 // fast path
1760 inline void prefetch_chunk_pd(void* start, int size_words);
1761 void patch_return(intptr_t* sp, bool is_last);
1762
1763 // slow path
1764 NOINLINE intptr_t* thaw_slow(stackChunkOop chunk, bool return_barrier);
1765
1766 private:
1767 void recurse_thaw(const frame& heap_frame, frame& caller, int num_frames, bool top);
1768 template<typename FKind> bool recurse_thaw_java_frame(frame& caller, int num_frames);
1769 void finalize_thaw(frame& entry, int argsize);
1770
1771 inline bool seen_by_gc();
1772
1773 inline void before_thaw_java_frame(const frame& hf, const frame& caller, bool bottom, int num_frame);
1774 inline void after_thaw_java_frame(const frame& f, bool bottom);
1775 inline void patch(frame& f, const frame& caller, bool bottom);
1776 void clear_bitmap_bits(address start, address end);
1777
1778 NOINLINE void recurse_thaw_interpreted_frame(const frame& hf, frame& caller, int num_frames);
1779 void recurse_thaw_compiled_frame(const frame& hf, frame& caller, int num_frames, bool stub_caller);
1780 void recurse_thaw_stub_frame(const frame& hf, frame& caller, int num_frames);
1781 void finish_thaw(frame& f);
1782
1783 void push_return_frame(frame& f);
1784 inline frame new_entry_frame();
1785 template<typename FKind> frame new_stack_frame(const frame& hf, frame& caller, bool bottom);
1786 inline void patch_pd(frame& f, const frame& sender);
1787 inline intptr_t* align(const frame& hf, intptr_t* frame_sp, frame& caller, bool bottom);
1788
1789 void maybe_set_fastpath(intptr_t* sp) { if (sp > _fastpath) _fastpath = sp; }
1790
1791 static inline void derelativize_interpreted_frame_metadata(const frame& hf, const frame& f);
1792
1793 public:
1794 CONT_JFR_ONLY(FreezeThawJfrInfo& jfr_info() { return _jfr_info; })
1795 };
1796
1797 template <typename ConfigT>
1798 class Thaw : public ThawBase {
1799 public:
1800 Thaw(JavaThread* thread, ContinuationWrapper& cont) : ThawBase(thread, cont) {}
1801
1802 inline bool can_thaw_fast(stackChunkOop chunk) {
1803 return !_barriers
1804 && _thread->cont_fastpath_thread_state()
1805 && !chunk->has_thaw_slowpath_condition()
1806 && !PreserveFramePointer;
1807 }
1808
1809 inline intptr_t* thaw(Continuation::thaw_kind kind);
1810 NOINLINE intptr_t* thaw_fast(stackChunkOop chunk);
1811 inline void patch_caller_links(intptr_t* sp, intptr_t* bottom);
1812 };
1813
1814 template <typename ConfigT>
1815 inline intptr_t* Thaw<ConfigT>::thaw(Continuation::thaw_kind kind) {
1816 verify_continuation(_cont.continuation());
1817 assert(!jdk_internal_vm_Continuation::done(_cont.continuation()), "");
1818 assert(!_cont.is_empty(), "");
1819
1820 stackChunkOop chunk = _cont.tail();
1821 assert(chunk != nullptr, "guaranteed by prepare_thaw");
1822 assert(!chunk->is_empty(), "guaranteed by prepare_thaw");
1823
1824 _barriers = chunk->requires_barriers();
1825 return (LIKELY(can_thaw_fast(chunk))) ? thaw_fast(chunk)
1826 : thaw_slow(chunk, kind != Continuation::thaw_top);
1827 }
1828
1829 class ReconstructedStack : public StackObj {
1830 intptr_t* _base; // _cont.entrySP(); // top of the entry frame
1831 int _thaw_size;
1832 int _argsize;
1833 public:
1834 ReconstructedStack(intptr_t* base, int thaw_size, int argsize)
1835 : _base(base), _thaw_size(thaw_size - (argsize == 0 ? frame::metadata_words_at_top : 0)), _argsize(argsize) {
1836 // The only possible source of misalignment is stack-passed arguments b/c compiled frames are 16-byte aligned.
1837 assert(argsize != 0 || (_base - _thaw_size) == ContinuationHelper::frame_align_pointer(_base - _thaw_size), "");
1838 // We're at most one alignment word away from entrySP
1839 assert(_base - 1 <= top() + total_size() + frame::metadata_words_at_bottom, "missed entry frame");
1840 }
1841
1842 int entry_frame_extension() const { return _argsize + (_argsize > 0 ? frame::metadata_words_at_top : 0); }
1843
1844 // top and bottom stack pointers
1845 intptr_t* sp() const { return ContinuationHelper::frame_align_pointer(_base - _thaw_size); }
1846 intptr_t* bottom_sp() const { return ContinuationHelper::frame_align_pointer(_base - entry_frame_extension()); }
1847
1848 // several operations operate on the totality of the stack being reconstructed,
1849 // including the metadata words
1850 intptr_t* top() const { return sp() - frame::metadata_words_at_bottom; }
1851 int total_size() const { return _thaw_size + frame::metadata_words_at_bottom; }
1852 };
1853
1854 inline void ThawBase::clear_chunk(stackChunkOop chunk) {
1855 chunk->set_sp(chunk->stack_size());
1856 chunk->set_argsize(0);
1857 chunk->set_max_thawing_size(0);
1858 }
1859
1860 int ThawBase::remove_top_compiled_frame_from_chunk(stackChunkOop chunk, int &argsize) {
1861 bool empty = false;
1862 StackChunkFrameStream<ChunkFrames::CompiledOnly> f(chunk);
1863 DEBUG_ONLY(intptr_t* const chunk_sp = chunk->start_address() + chunk->sp();)
1864 assert(chunk_sp == f.sp(), "");
1865 assert(chunk_sp == f.unextended_sp(), "");
1866
1867 const int frame_size = f.cb()->frame_size();
1868 argsize = f.stack_argsize();
1869
1870 f.next(SmallRegisterMap::instance, true /* stop */);
1871 empty = f.is_done();
1872 assert(!empty || argsize == chunk->argsize(), "");
1873
1874 if (empty) {
1875 clear_chunk(chunk);
1876 } else {
1877 chunk->set_sp(chunk->sp() + frame_size);
1878 chunk->set_max_thawing_size(chunk->max_thawing_size() - frame_size);
1879 // We set chunk->pc to the return pc into the next frame
1880 chunk->set_pc(f.pc());
1881 #ifdef ASSERT
1882 {
1883 intptr_t* retaddr_slot = (chunk_sp
1884 + frame_size
1885 - frame::sender_sp_ret_address_offset());
1886 assert(f.pc() == ContinuationHelper::return_address_at(retaddr_slot),
1887 "unexpected pc");
1888 }
1889 #endif
1890 }
1891 assert(empty == chunk->is_empty(), "");
1892 // returns the size required to store the frame on stack, and because it is a
1893 // compiled frame, it must include a copy of the arguments passed by the caller
1894 return frame_size + argsize + frame::metadata_words_at_top;
1895 }
1896
1897 void ThawBase::copy_from_chunk(intptr_t* from, intptr_t* to, int size) {
1898 assert(to >= _top_stack_address, "overwrote past thawing space"
1899 " to: " INTPTR_FORMAT " top_address: " INTPTR_FORMAT, p2i(to), p2i(_top_stack_address));
1900 assert(to + size <= _cont.entrySP(), "overwrote past thawing space");
1901 _cont.tail()->copy_from_chunk_to_stack(from, to, size);
1902 CONT_JFR_ONLY(_jfr_info.record_size_copied(size);)
1903 }
1904
1905 void ThawBase::patch_return(intptr_t* sp, bool is_last) {
1906 log_develop_trace(continuations)("thaw_fast patching -- sp: " INTPTR_FORMAT, p2i(sp));
1907
1908 address pc = !is_last ? StubRoutines::cont_returnBarrier() : _cont.entryPC();
1909 ContinuationHelper::patch_return_address_at(
1910 sp - frame::sender_sp_ret_address_offset(),
1911 pc);
1912 }
1913
1914 template <typename ConfigT>
1915 NOINLINE intptr_t* Thaw<ConfigT>::thaw_fast(stackChunkOop chunk) {
1916 assert(chunk == _cont.tail(), "");
1917 assert(!chunk->has_mixed_frames(), "");
1918 assert(!chunk->requires_barriers(), "");
1919 assert(!chunk->has_bitmap(), "");
1920 assert(!_thread->is_interp_only_mode(), "");
1921
1922 LogTarget(Trace, continuations) lt;
1923 if (lt.develop_is_enabled()) {
1924 LogStream ls(lt);
1925 ls.print_cr("thaw_fast");
1926 chunk->print_on(true, &ls);
1927 }
1928
1929 // Below this heuristic, we thaw the whole chunk, above it we thaw just one frame.
1930 static const int threshold = 500; // words
1931
1932 const int full_chunk_size = chunk->stack_size() - chunk->sp(); // this initial size could be reduced if it's a partial thaw
1933 int argsize, thaw_size;
1934
1935 intptr_t* const chunk_sp = chunk->start_address() + chunk->sp();
1936
1937 bool partial, empty;
1938 if (LIKELY(!TEST_THAW_ONE_CHUNK_FRAME && (full_chunk_size < threshold))) {
1939 prefetch_chunk_pd(chunk->start_address(), full_chunk_size); // prefetch anticipating memcpy starting at highest address
1940
1941 partial = false;
1942 argsize = chunk->argsize(); // must be called *before* clearing the chunk
1943 clear_chunk(chunk);
1944 thaw_size = full_chunk_size;
1945 empty = true;
1946 } else { // thaw a single frame
1947 partial = true;
1948 thaw_size = remove_top_compiled_frame_from_chunk(chunk, argsize);
1949 empty = chunk->is_empty();
1950 }
1951
1952 // Are we thawing the last frame(s) in the continuation
1953 const bool is_last = empty && chunk->parent() == nullptr;
1954 assert(!is_last || argsize == 0, "");
1955
1956 log_develop_trace(continuations)("thaw_fast partial: %d is_last: %d empty: %d size: %d argsize: %d entrySP: " PTR_FORMAT,
1957 partial, is_last, empty, thaw_size, argsize, p2i(_cont.entrySP()));
1958
1959 ReconstructedStack rs(_cont.entrySP(), thaw_size, argsize);
1960
1961 // also copy metadata words at frame bottom
1962 copy_from_chunk(chunk_sp - frame::metadata_words_at_bottom, rs.top(), rs.total_size());
1963
1964 // update the ContinuationEntry
1965 _cont.set_argsize(argsize);
1966 log_develop_trace(continuations)("setting entry argsize: %d", _cont.argsize());
1967 assert(rs.bottom_sp() == _cont.entry()->bottom_sender_sp(), "");
1968
1969 // install the return barrier if not last frame, or the entry's pc if last
1970 patch_return(rs.bottom_sp(), is_last);
1971
1972 // insert the back links from callee to caller frames
1973 patch_caller_links(rs.top(), rs.top() + rs.total_size());
1974
1975 assert(is_last == _cont.is_empty(), "");
1976 assert(_cont.chunk_invariant(), "");
1977
1978 #if CONT_JFR
1979 EventContinuationThawFast e;
1980 if (e.should_commit()) {
1981 e.set_id(cast_from_oop<u8>(chunk));
1982 e.set_size(thaw_size << LogBytesPerWord);
1983 e.set_full(!partial);
1984 e.commit();
1985 }
1986 #endif
1987
1988 #ifdef ASSERT
1989 set_anchor(_thread, rs.sp());
1990 log_frames(_thread);
1991 if (LoomDeoptAfterThaw) {
1992 do_deopt_after_thaw(_thread);
1993 }
1994 clear_anchor(_thread);
1995 #endif
1996
1997 return rs.sp();
1998 }
1999
2000 inline bool ThawBase::seen_by_gc() {
2001 return _barriers || _cont.tail()->is_gc_mode();
2002 }
2003
2004 NOINLINE intptr_t* ThawBase::thaw_slow(stackChunkOop chunk, bool return_barrier) {
2005 LogTarget(Trace, continuations) lt;
2006 if (lt.develop_is_enabled()) {
2007 LogStream ls(lt);
2008 ls.print_cr("thaw slow return_barrier: %d " INTPTR_FORMAT, return_barrier, p2i(chunk));
2009 chunk->print_on(true, &ls);
2010 }
2011
2012 #if CONT_JFR
2013 EventContinuationThawSlow e;
2014 if (e.should_commit()) {
2015 e.set_id(cast_from_oop<u8>(_cont.continuation()));
2016 e.commit();
2017 }
2018 #endif
2019
2020 DEBUG_ONLY(_frames = 0;)
2021 _align_size = 0;
2022 int num_frames = (return_barrier ? 1 : 2);
2023
2024 _stream = StackChunkFrameStream<ChunkFrames::Mixed>(chunk);
2025 _top_unextended_sp_before_thaw = _stream.unextended_sp();
2026
2027 frame heap_frame = _stream.to_frame();
2028 if (lt.develop_is_enabled()) {
2029 LogStream ls(lt);
2030 ls.print_cr("top hframe before (thaw):");
2031 assert(heap_frame.is_heap_frame(), "should have created a relative frame");
2032 heap_frame.print_value_on(&ls, nullptr);
2033 }
2034
2035 #if INCLUDE_ZGC || INCLUDE_SHENANDOAHGC
2036 if (UseZGC || UseShenandoahGC) {
2037 _cont.tail()->relativize_derived_pointers_concurrently();
2038 }
2039 #endif
2040
2041 frame caller; // the thawed caller on the stack
2042 recurse_thaw(heap_frame, caller, num_frames, true);
2043 finish_thaw(caller); // caller is now the topmost thawed frame
2044 _cont.write();
2045
2046 assert(_cont.chunk_invariant(), "");
2047
2048 JVMTI_ONLY(if (!return_barrier) invalidate_jvmti_stack(_thread));
2049
2050 _thread->set_cont_fastpath(_fastpath);
2051
2052 intptr_t* sp = caller.sp();
2053 return sp;
2054 }
2055
2056 void ThawBase::recurse_thaw(const frame& heap_frame, frame& caller, int num_frames, bool top) {
2057 log_develop_debug(continuations)("thaw num_frames: %d", num_frames);
2058 assert(!_cont.is_empty(), "no more frames");
2059 assert(num_frames > 0, "");
2060 assert(!heap_frame.is_empty(), "");
2061
2062 if (top && heap_frame.is_safepoint_blob_frame()) {
2063 assert(ContinuationHelper::Frame::is_stub(heap_frame.cb()), "cb: %s", heap_frame.cb()->name());
2064 recurse_thaw_stub_frame(heap_frame, caller, num_frames);
2065 } else if (!heap_frame.is_interpreted_frame()) {
2066 recurse_thaw_compiled_frame(heap_frame, caller, num_frames, false);
2067 } else {
2068 recurse_thaw_interpreted_frame(heap_frame, caller, num_frames);
2069 }
2070 }
2071
2072 template<typename FKind>
2073 bool ThawBase::recurse_thaw_java_frame(frame& caller, int num_frames) {
2074 assert(num_frames > 0, "");
2075
2076 DEBUG_ONLY(_frames++;)
2077
2078 int argsize = _stream.stack_argsize();
2079
2080 _stream.next(SmallRegisterMap::instance);
2081 assert(_stream.to_frame().is_empty() == _stream.is_done(), "");
2082
2083 // we never leave a compiled caller of an interpreted frame as the top frame in the chunk
2084 // as it makes detecting that situation and adjusting unextended_sp tricky
2085 if (num_frames == 1 && !_stream.is_done() && FKind::interpreted && _stream.is_compiled()) {
2086 log_develop_trace(continuations)("thawing extra compiled frame to not leave a compiled interpreted-caller at top");
2087 num_frames++;
2088 }
2089
2090 if (num_frames == 1 || _stream.is_done()) { // end recursion
2091 finalize_thaw(caller, FKind::interpreted ? 0 : argsize);
2092 return true; // bottom
2093 } else { // recurse
2094 recurse_thaw(_stream.to_frame(), caller, num_frames - 1, false);
2095 return false;
2096 }
2097 }
2098
2099 void ThawBase::finalize_thaw(frame& entry, int argsize) {
2100 stackChunkOop chunk = _cont.tail();
2101
2102 if (!_stream.is_done()) {
2103 assert(_stream.sp() >= chunk->sp_address(), "");
2104 chunk->set_sp(chunk->to_offset(_stream.sp()));
2105 chunk->set_pc(_stream.pc());
2106 } else {
2107 chunk->set_argsize(0);
2108 chunk->set_sp(chunk->stack_size());
2109 chunk->set_pc(nullptr);
2110 }
2111 assert(_stream.is_done() == chunk->is_empty(), "");
2112
2113 int total_thawed = pointer_delta_as_int(_stream.unextended_sp(), _top_unextended_sp_before_thaw);
2114 chunk->set_max_thawing_size(chunk->max_thawing_size() - total_thawed);
2115
2116 _cont.set_argsize(argsize);
2117 entry = new_entry_frame();
2118
2119 assert(entry.sp() == _cont.entrySP(), "");
2120 assert(Continuation::is_continuation_enterSpecial(entry), "");
2121 assert(_cont.is_entry_frame(entry), "");
2122 }
2123
2124 inline void ThawBase::before_thaw_java_frame(const frame& hf, const frame& caller, bool bottom, int num_frame) {
2125 LogTarget(Trace, continuations) lt;
2126 if (lt.develop_is_enabled()) {
2127 LogStream ls(lt);
2128 ls.print_cr("======== THAWING FRAME: %d", num_frame);
2129 assert(hf.is_heap_frame(), "should be");
2130 hf.print_value_on(&ls, nullptr);
2131 }
2132 assert(bottom == _cont.is_entry_frame(caller), "bottom: %d is_entry_frame: %d", bottom, _cont.is_entry_frame(hf));
2133 }
2134
2135 inline void ThawBase::after_thaw_java_frame(const frame& f, bool bottom) {
2136 #ifdef ASSERT
2137 LogTarget(Trace, continuations) lt;
2138 if (lt.develop_is_enabled()) {
2139 LogStream ls(lt);
2140 ls.print_cr("thawed frame:");
2141 print_frame_layout(f, false, &ls); // f.print_on(&ls);
2142 }
2143 #endif
2144 }
2145
2146 inline void ThawBase::patch(frame& f, const frame& caller, bool bottom) {
2147 assert(!bottom || caller.fp() == _cont.entryFP(), "");
2148 if (bottom) {
2149 ContinuationHelper::Frame::patch_pc(caller, _cont.is_empty() ? caller.pc()
2150 : StubRoutines::cont_returnBarrier());
2151 } else {
2152 // caller might have been deoptimized during thaw but we've overwritten the return address when copying f from the heap.
2153 // If the caller is not deoptimized, pc is unchanged.
2154 ContinuationHelper::Frame::patch_pc(caller, caller.raw_pc());
2155 }
2156
2157 patch_pd(f, caller);
2158
2159 if (f.is_interpreted_frame()) {
2160 ContinuationHelper::InterpretedFrame::patch_sender_sp(f, caller);
2161 }
2162
2163 assert(!bottom || !_cont.is_empty() || Continuation::is_continuation_entry_frame(f, nullptr), "");
2164 assert(!bottom || (_cont.is_empty() != Continuation::is_cont_barrier_frame(f)), "");
2165 }
2166
2167 void ThawBase::clear_bitmap_bits(address start, address end) {
2168 assert(is_aligned(start, wordSize), "should be aligned: " PTR_FORMAT, p2i(start));
2169 assert(is_aligned(end, VMRegImpl::stack_slot_size), "should be aligned: " PTR_FORMAT, p2i(end));
2170
2171 // we need to clear the bits that correspond to arguments as they reside in the caller frame
2172 // or they will keep objects that are otherwise unreachable alive.
2173
2174 // Align `end` if UseCompressedOops is not set to avoid UB when calculating the bit index, since
2175 // `end` could be at an odd number of stack slots from `start`, i.e might not be oop aligned.
2176 // If that's the case the bit range corresponding to the last stack slot should not have bits set
2177 // anyways and we assert that before returning.
2178 address effective_end = UseCompressedOops ? end : align_down(end, wordSize);
2179 log_develop_trace(continuations)("clearing bitmap for " INTPTR_FORMAT " - " INTPTR_FORMAT, p2i(start), p2i(effective_end));
2180 stackChunkOop chunk = _cont.tail();
2181 chunk->bitmap().clear_range(chunk->bit_index_for(start), chunk->bit_index_for(effective_end));
2182 assert(effective_end == end || !chunk->bitmap().at(chunk->bit_index_for(effective_end)), "bit should not be set");
2183 }
2184
2185 NOINLINE void ThawBase::recurse_thaw_interpreted_frame(const frame& hf, frame& caller, int num_frames) {
2186 assert(hf.is_interpreted_frame(), "");
2187
2188 if (UNLIKELY(seen_by_gc())) {
2189 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance);
2190 }
2191
2192 const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::InterpretedFrame>(caller, num_frames);
2193
2194 DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2195
2196 _align_size += frame::align_wiggle; // possible added alignment for internal interpreted frame alignment om AArch64
2197
2198 frame f = new_stack_frame<ContinuationHelper::InterpretedFrame>(hf, caller, is_bottom_frame);
2199
2200 intptr_t* const stack_frame_top = f.sp() + frame::metadata_words_at_top;
2201 intptr_t* const stack_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(f);
2202 intptr_t* const heap_frame_top = hf.unextended_sp() + frame::metadata_words_at_top;
2203 intptr_t* const heap_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(hf);
2204
2205 assert(hf.is_heap_frame(), "should be");
2206 assert(!f.is_heap_frame(), "should not be");
2207
2208 const int fsize = pointer_delta_as_int(heap_frame_bottom, heap_frame_top);
2209 assert((stack_frame_bottom == stack_frame_top + fsize), "");
2210
2211 // Some architectures (like AArch64/PPC64/RISC-V) add padding between the locals and the fixed_frame to keep the fp 16-byte-aligned.
2212 // On those architectures we freeze the padding in order to keep the same fp-relative offsets in the fixed_frame.
2213 copy_from_chunk(heap_frame_top, stack_frame_top, fsize);
2214
2215 // Make sure the relativized locals is already set.
2216 assert(f.interpreter_frame_local_at(0) == stack_frame_bottom - 1, "invalid frame bottom");
2217
2218 derelativize_interpreted_frame_metadata(hf, f);
2219 patch(f, caller, is_bottom_frame);
2220
2221 assert(f.is_interpreted_frame_valid(_cont.thread()), "invalid thawed frame");
2222 assert(stack_frame_bottom <= ContinuationHelper::Frame::frame_top(caller), "");
2223
2224 CONT_JFR_ONLY(_jfr_info.record_interpreted_frame();)
2225
2226 maybe_set_fastpath(f.sp());
2227
2228 const int locals = hf.interpreter_frame_method()->max_locals();
2229
2230 if (!is_bottom_frame) {
2231 // can only fix caller once this frame is thawed (due to callee saved regs)
2232 _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance);
2233 } else if (_cont.tail()->has_bitmap() && locals > 0) {
2234 assert(hf.is_heap_frame(), "should be");
2235 address start = (address)(heap_frame_bottom - locals);
2236 address end = (address)heap_frame_bottom;
2237 clear_bitmap_bits(start, end);
2238 }
2239
2240 DEBUG_ONLY(after_thaw_java_frame(f, is_bottom_frame);)
2241 caller = f;
2242 }
2243
2244 void ThawBase::recurse_thaw_compiled_frame(const frame& hf, frame& caller, int num_frames, bool stub_caller) {
2245 assert(!hf.is_interpreted_frame(), "");
2246 assert(_cont.is_preempted() || !stub_caller, "stub caller not at preemption");
2247
2248 if (!stub_caller && UNLIKELY(seen_by_gc())) { // recurse_thaw_stub_frame already invoked our barriers with a full regmap
2249 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance);
2250 }
2251
2252 const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::CompiledFrame>(caller, num_frames);
2253
2254 DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2255
2256 assert(caller.sp() == caller.unextended_sp(), "");
2257
2258 if ((!is_bottom_frame && caller.is_interpreted_frame()) || (is_bottom_frame && Interpreter::contains(_cont.tail()->pc()))) {
2259 _align_size += frame::align_wiggle; // we add one whether or not we've aligned because we add it in freeze_interpreted_frame
2260 }
2261
2262 // new_stack_frame must construct the resulting frame using hf.pc() rather than hf.raw_pc() because the frame is not
2263 // yet laid out in the stack, and so the original_pc is not stored in it.
2264 // As a result, f.is_deoptimized_frame() is always false and we must test hf to know if the frame is deoptimized.
2265 frame f = new_stack_frame<ContinuationHelper::CompiledFrame>(hf, caller, is_bottom_frame);
2266 intptr_t* const stack_frame_top = f.sp();
2267 intptr_t* const heap_frame_top = hf.unextended_sp();
2268
2269 const int added_argsize = (is_bottom_frame || caller.is_interpreted_frame()) ? hf.compiled_frame_stack_argsize() : 0;
2270 int fsize = ContinuationHelper::CompiledFrame::size(hf) + added_argsize;
2271 assert(fsize <= (int)(caller.unextended_sp() - f.unextended_sp()), "");
2272
2273 intptr_t* from = heap_frame_top - frame::metadata_words_at_bottom;
2274 intptr_t* to = stack_frame_top - frame::metadata_words_at_bottom;
2275 // copy metadata, except the metadata at the top of the (unextended) entry frame
2276 int sz = fsize + frame::metadata_words_at_bottom + (is_bottom_frame && added_argsize == 0 ? 0 : frame::metadata_words_at_top);
2277
2278 // If we're the bottom-most thawed frame, we're writing to within one word from entrySP
2279 // (we might have one padding word for alignment)
2280 assert(!is_bottom_frame || (_cont.entrySP() - 1 <= to + sz && to + sz <= _cont.entrySP()), "");
2281 assert(!is_bottom_frame || hf.compiled_frame_stack_argsize() != 0 || (to + sz && to + sz == _cont.entrySP()), "");
2282
2283 copy_from_chunk(from, to, sz); // copying good oops because we invoked barriers above
2284
2285 patch(f, caller, is_bottom_frame);
2286
2287 // f.is_deoptimized_frame() is always false and we must test hf.is_deoptimized_frame() (see comment above)
2288 assert(!f.is_deoptimized_frame(), "");
2289 if (hf.is_deoptimized_frame()) {
2290 maybe_set_fastpath(f.sp());
2291 } else if (_thread->is_interp_only_mode()
2292 || (_cont.is_preempted() && f.cb()->as_nmethod()->is_marked_for_deoptimization())) {
2293 // The caller of the safepoint stub when the continuation is preempted is not at a call instruction, and so
2294 // cannot rely on nmethod patching for deopt.
2295 assert(_thread->is_interp_only_mode() || stub_caller, "expected a stub-caller");
2296
2297 log_develop_trace(continuations)("Deoptimizing thawed frame");
2298 DEBUG_ONLY(ContinuationHelper::Frame::patch_pc(f, nullptr));
2299
2300 f.deoptimize(nullptr); // the null thread simply avoids the assertion in deoptimize which we're not set up for
2301 assert(f.is_deoptimized_frame(), "");
2302 assert(ContinuationHelper::Frame::is_deopt_return(f.raw_pc(), f), "");
2303 maybe_set_fastpath(f.sp());
2304 }
2305
2306 if (!is_bottom_frame) {
2307 // can only fix caller once this frame is thawed (due to callee saved regs); this happens on the stack
2308 _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance);
2309 } else if (_cont.tail()->has_bitmap() && added_argsize > 0) {
2310 address start = (address)(heap_frame_top + ContinuationHelper::CompiledFrame::size(hf) + frame::metadata_words_at_top);
2311 int stack_args_slots = f.cb()->as_nmethod()->num_stack_arg_slots(false /* rounded */);
2312 int argsize_in_bytes = stack_args_slots * VMRegImpl::stack_slot_size;
2313 clear_bitmap_bits(start, start + argsize_in_bytes);
2314 }
2315
2316 DEBUG_ONLY(after_thaw_java_frame(f, is_bottom_frame);)
2317 caller = f;
2318 }
2319
2320 void ThawBase::recurse_thaw_stub_frame(const frame& hf, frame& caller, int num_frames) {
2321 DEBUG_ONLY(_frames++;)
2322
2323 {
2324 RegisterMap map(nullptr,
2325 RegisterMap::UpdateMap::include,
2326 RegisterMap::ProcessFrames::skip,
2327 RegisterMap::WalkContinuation::skip);
2328 map.set_include_argument_oops(false);
2329 _stream.next(&map);
2330 assert(!_stream.is_done(), "");
2331 if (UNLIKELY(seen_by_gc())) { // we're now doing this on the stub's caller
2332 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, &map);
2333 }
2334 assert(!_stream.is_done(), "");
2335 }
2336
2337 recurse_thaw_compiled_frame(_stream.to_frame(), caller, num_frames, true); // this could be deoptimized
2338
2339 DEBUG_ONLY(before_thaw_java_frame(hf, caller, false, num_frames);)
2340
2341 assert(ContinuationHelper::Frame::is_stub(hf.cb()), "");
2342 assert(caller.sp() == caller.unextended_sp(), "");
2343 assert(!caller.is_interpreted_frame(), "");
2344
2345 int fsize = ContinuationHelper::StubFrame::size(hf);
2346
2347 frame f = new_stack_frame<ContinuationHelper::StubFrame>(hf, caller, false);
2348 intptr_t* stack_frame_top = f.sp();
2349 intptr_t* heap_frame_top = hf.sp();
2350
2351 copy_from_chunk(heap_frame_top - frame::metadata_words, stack_frame_top - frame::metadata_words,
2352 fsize + frame::metadata_words);
2353
2354 { // can only fix caller once this frame is thawed (due to callee saved regs)
2355 RegisterMap map(nullptr,
2356 RegisterMap::UpdateMap::include,
2357 RegisterMap::ProcessFrames::skip,
2358 RegisterMap::WalkContinuation::skip); // map.clear();
2359 map.set_include_argument_oops(false);
2360 f.oop_map()->update_register_map(&f, &map);
2361 ContinuationHelper::update_register_map_with_callee(caller, &map);
2362 _cont.tail()->fix_thawed_frame(caller, &map);
2363 }
2364
2365 DEBUG_ONLY(after_thaw_java_frame(f, false);)
2366 caller = f;
2367 }
2368
2369 void ThawBase::finish_thaw(frame& f) {
2370 stackChunkOop chunk = _cont.tail();
2371
2372 if (chunk->is_empty()) {
2373 // Only remove chunk from list if it can't be reused for another freeze
2374 if (seen_by_gc()) {
2375 _cont.set_tail(chunk->parent());
2376 } else {
2377 chunk->set_has_mixed_frames(false);
2378 }
2379 chunk->set_max_thawing_size(0);
2380 assert(chunk->argsize() == 0, "");
2381 } else {
2382 chunk->set_max_thawing_size(chunk->max_thawing_size() - _align_size);
2383 }
2384 assert(chunk->is_empty() == (chunk->max_thawing_size() == 0), "");
2385
2386 if (!is_aligned(f.sp(), frame::frame_alignment)) {
2387 assert(f.is_interpreted_frame(), "");
2388 f.set_sp(align_down(f.sp(), frame::frame_alignment));
2389 }
2390 push_return_frame(f);
2391 chunk->fix_thawed_frame(f, SmallRegisterMap::instance); // can only fix caller after push_return_frame (due to callee saved regs)
2392
2393 assert(_cont.is_empty() == _cont.last_frame().is_empty(), "");
2394
2395 log_develop_trace(continuations)("thawed %d frames", _frames);
2396
2397 LogTarget(Trace, continuations) lt;
2398 if (lt.develop_is_enabled()) {
2399 LogStream ls(lt);
2400 ls.print_cr("top hframe after (thaw):");
2401 _cont.last_frame().print_value_on(&ls, nullptr);
2402 }
2403 }
2404
2405 void ThawBase::push_return_frame(frame& f) { // see generate_cont_thaw
2406 assert(!f.is_compiled_frame() || f.is_deoptimized_frame() == f.cb()->as_nmethod()->is_deopt_pc(f.raw_pc()), "");
2407 assert(!f.is_compiled_frame() || f.is_deoptimized_frame() == (f.pc() != f.raw_pc()), "");
2408
2409 LogTarget(Trace, continuations) lt;
2410 if (lt.develop_is_enabled()) {
2411 LogStream ls(lt);
2412 ls.print_cr("push_return_frame");
2413 f.print_value_on(&ls, nullptr);
2414 }
2415
2416 assert(f.sp() - frame::metadata_words_at_bottom >= _top_stack_address, "overwrote past thawing space"
2417 " to: " INTPTR_FORMAT " top_address: " INTPTR_FORMAT, p2i(f.sp() - frame::metadata_words), p2i(_top_stack_address));
2418 ContinuationHelper::Frame::patch_pc(f, f.raw_pc()); // in case we want to deopt the frame in a full transition, this is checked.
2419 ContinuationHelper::push_pd(f);
2420
2421 assert(ContinuationHelper::Frame::assert_frame_laid_out(f), "");
2422 }
2423
2424 // returns new top sp
2425 // called after preparations (stack overflow check and making room)
2426 template<typename ConfigT>
2427 static inline intptr_t* thaw_internal(JavaThread* thread, const Continuation::thaw_kind kind) {
2428 assert(thread == JavaThread::current(), "Must be current thread");
2429
2430 CONT_JFR_ONLY(EventContinuationThaw event;)
2431
2432 log_develop_trace(continuations)("~~~~ thaw kind: %d sp: " INTPTR_FORMAT, kind, p2i(thread->last_continuation()->entry_sp()));
2433
2434 ContinuationEntry* entry = thread->last_continuation();
2435 assert(entry != nullptr, "");
2436 oop oopCont = entry->cont_oop(thread);
2437
2438 assert(!jdk_internal_vm_Continuation::done(oopCont), "");
2439 assert(oopCont == get_continuation(thread), "");
2440 verify_continuation(oopCont);
2441
2442 assert(entry->is_virtual_thread() == (entry->scope(thread) == java_lang_VirtualThread::vthread_scope()), "");
2443
2444 ContinuationWrapper cont(thread, oopCont);
2445 log_develop_debug(continuations)("THAW #" INTPTR_FORMAT " " INTPTR_FORMAT, cont.hash(), p2i((oopDesc*)oopCont));
2446
2447 #ifdef ASSERT
2448 set_anchor_to_entry(thread, cont.entry());
2449 log_frames(thread);
2450 clear_anchor(thread);
2451 #endif
2452
2453 Thaw<ConfigT> thw(thread, cont);
2454 intptr_t* const sp = thw.thaw(kind);
2455 assert(is_aligned(sp, frame::frame_alignment), "");
2456
2457 // All the frames have been thawed so we know they don't hold any monitors
2458 assert(thread->held_monitor_count() == 0, "Must be");
2459
2460 #ifdef ASSERT
2461 intptr_t* sp0 = sp;
2462 set_anchor(thread, sp0);
2463 log_frames(thread);
2464 if (LoomVerifyAfterThaw) {
2465 assert(do_verify_after_thaw(thread, cont.tail(), tty), "");
2466 }
2467 assert(ContinuationEntry::assert_entry_frame_laid_out(thread), "");
2468 clear_anchor(thread);
2469
2470 LogTarget(Trace, continuations) lt;
2471 if (lt.develop_is_enabled()) {
2472 LogStream ls(lt);
2473 ls.print_cr("Jumping to frame (thaw):");
2474 frame(sp).print_value_on(&ls, nullptr);
2475 }
2476 #endif
2477
2478 CONT_JFR_ONLY(thw.jfr_info().post_jfr_event(&event, cont.continuation(), thread);)
2479
2480 verify_continuation(cont.continuation());
2481 log_develop_debug(continuations)("=== End of thaw #" INTPTR_FORMAT, cont.hash());
2482
2483 return sp;
2484 }
2485
2486 #ifdef ASSERT
2487 static void do_deopt_after_thaw(JavaThread* thread) {
2488 int i = 0;
2489 StackFrameStream fst(thread, true, false);
2490 fst.register_map()->set_include_argument_oops(false);
2491 ContinuationHelper::update_register_map_with_callee(*fst.current(), fst.register_map());
2492 for (; !fst.is_done(); fst.next()) {
2493 if (fst.current()->cb()->is_nmethod()) {
2494 nmethod* nm = fst.current()->cb()->as_nmethod();
2495 if (!nm->method()->is_continuation_native_intrinsic()) {
2496 nm->make_deoptimized();
2497 }
2498 }
2499 }
2500 }
2501
2502 class ThawVerifyOopsClosure: public OopClosure {
2503 intptr_t* _p;
2504 outputStream* _st;
2505 bool is_good_oop(oop o) {
2506 return dbg_is_safe(o, -1) && dbg_is_safe(o->klass(), -1) && oopDesc::is_oop(o) && o->klass()->is_klass();
2507 }
2508 public:
2509 ThawVerifyOopsClosure(outputStream* st) : _p(nullptr), _st(st) {}
2510 intptr_t* p() { return _p; }
2511 void reset() { _p = nullptr; }
2512
2513 virtual void do_oop(oop* p) {
2514 oop o = *p;
2515 if (o == nullptr || is_good_oop(o)) {
2516 return;
2517 }
2518 _p = (intptr_t*)p;
2519 _st->print_cr("*** non-oop " PTR_FORMAT " found at " PTR_FORMAT, p2i(*p), p2i(p));
2520 }
2521 virtual void do_oop(narrowOop* p) {
2522 oop o = RawAccess<>::oop_load(p);
2523 if (o == nullptr || is_good_oop(o)) {
2524 return;
2525 }
2526 _p = (intptr_t*)p;
2527 _st->print_cr("*** (narrow) non-oop %x found at " PTR_FORMAT, (int)(*p), p2i(p));
2528 }
2529 };
2530
2531 static bool do_verify_after_thaw(JavaThread* thread, stackChunkOop chunk, outputStream* st) {
2532 assert(thread->has_last_Java_frame(), "");
2533
2534 ResourceMark rm;
2535 ThawVerifyOopsClosure cl(st);
2536 NMethodToOopClosure cf(&cl, false);
2537
2538 StackFrameStream fst(thread, true, false);
2539 fst.register_map()->set_include_argument_oops(false);
2540 ContinuationHelper::update_register_map_with_callee(*fst.current(), fst.register_map());
2541 for (; !fst.is_done() && !Continuation::is_continuation_enterSpecial(*fst.current()); fst.next()) {
2542 if (fst.current()->cb()->is_nmethod() && fst.current()->cb()->as_nmethod()->is_marked_for_deoptimization()) {
2543 st->print_cr(">>> do_verify_after_thaw deopt");
2544 fst.current()->deoptimize(nullptr);
2545 fst.current()->print_on(st);
2546 }
2547
2548 fst.current()->oops_do(&cl, &cf, fst.register_map());
2549 if (cl.p() != nullptr) {
2550 frame fr = *fst.current();
2551 st->print_cr("Failed for frame barriers: %d",chunk->requires_barriers());
2552 fr.print_on(st);
2553 if (!fr.is_interpreted_frame()) {
2554 st->print_cr("size: %d argsize: %d",
2555 ContinuationHelper::NonInterpretedUnknownFrame::size(fr),
2556 ContinuationHelper::NonInterpretedUnknownFrame::stack_argsize(fr));
2557 }
2558 VMReg reg = fst.register_map()->find_register_spilled_here(cl.p(), fst.current()->sp());
2559 if (reg != nullptr) {
2560 st->print_cr("Reg %s %d", reg->name(), reg->is_stack() ? (int)reg->reg2stack() : -99);
2561 }
2562 cl.reset();
2563 DEBUG_ONLY(thread->print_frame_layout();)
2564 if (chunk != nullptr) {
2565 chunk->print_on(true, st);
2566 }
2567 return false;
2568 }
2569 }
2570 return true;
2571 }
2572
2573 static void log_frames(JavaThread* thread) {
2574 const static int show_entry_callers = 3;
2575 LogTarget(Trace, continuations) lt;
2576 if (!lt.develop_is_enabled()) {
2577 return;
2578 }
2579 LogStream ls(lt);
2580
2581 ls.print_cr("------- frames ---------");
2582 if (!thread->has_last_Java_frame()) {
2583 ls.print_cr("NO ANCHOR!");
2584 }
2585
2586 RegisterMap map(thread,
2587 RegisterMap::UpdateMap::include,
2588 RegisterMap::ProcessFrames::include,
2589 RegisterMap::WalkContinuation::skip);
2590 map.set_include_argument_oops(false);
2591
2592 if (false) {
2593 for (frame f = thread->last_frame(); !f.is_entry_frame(); f = f.sender(&map)) {
2594 f.print_on(&ls);
2595 }
2596 } else {
2597 map.set_skip_missing(true);
2598 ResetNoHandleMark rnhm;
2599 ResourceMark rm;
2600 HandleMark hm(Thread::current());
2601 FrameValues values;
2602
2603 int i = 0;
2604 int post_entry = -1;
2605 for (frame f = thread->last_frame(); !f.is_entry_frame(); f = f.sender(&map)) {
2606 f.describe(values, i++, &map);
2607 if (post_entry >= 0 || Continuation::is_continuation_enterSpecial(f))
2608 post_entry++;
2609 if (post_entry >= show_entry_callers)
2610 break;
2611 }
2612 values.print_on(thread, &ls);
2613 }
2614
2615 ls.print_cr("======= end frames =========");
2616 }
2617 #endif // ASSERT
2618
2619 #include CPU_HEADER_INLINE(continuationFreezeThaw)
2620
2621 #ifdef ASSERT
2622 static void print_frame_layout(const frame& f, bool callee_complete, outputStream* st) {
2623 ResourceMark rm;
2624 FrameValues values;
2625 assert(f.get_cb() != nullptr, "");
2626 RegisterMap map(f.is_heap_frame() ?
2627 nullptr :
2628 JavaThread::current(),
2629 RegisterMap::UpdateMap::include,
2630 RegisterMap::ProcessFrames::skip,
2631 RegisterMap::WalkContinuation::skip);
2632 map.set_include_argument_oops(false);
2633 map.set_skip_missing(true);
2634 if (callee_complete) {
2635 frame::update_map_with_saved_link(&map, ContinuationHelper::Frame::callee_link_address(f));
2636 }
2637 const_cast<frame&>(f).describe(values, 0, &map);
2638 values.print_on(static_cast<JavaThread*>(nullptr), st);
2639 }
2640 #endif
2641
2642 static address thaw_entry = nullptr;
2643 static address freeze_entry = nullptr;
2644
2645 address Continuation::thaw_entry() {
2646 return ::thaw_entry;
2647 }
2648
2649 address Continuation::freeze_entry() {
2650 return ::freeze_entry;
2651 }
2652
2653 class ConfigResolve {
2654 public:
2655 static void resolve() { resolve_compressed(); }
2656
2657 static void resolve_compressed() {
2658 UseCompressedOops ? resolve_gc<true>()
2659 : resolve_gc<false>();
2660 }
2661
2662 private:
2663 template <bool use_compressed>
2664 static void resolve_gc() {
2665 BarrierSet* bs = BarrierSet::barrier_set();
2666 assert(bs != nullptr, "freeze/thaw invoked before BarrierSet is set");
2667 switch (bs->kind()) {
2668 #define BARRIER_SET_RESOLVE_BARRIER_CLOSURE(bs_name) \
2669 case BarrierSet::bs_name: { \
2670 resolve<use_compressed, typename BarrierSet::GetType<BarrierSet::bs_name>::type>(); \
2671 } \
2672 break;
2673 FOR_EACH_CONCRETE_BARRIER_SET_DO(BARRIER_SET_RESOLVE_BARRIER_CLOSURE)
2674 #undef BARRIER_SET_RESOLVE_BARRIER_CLOSURE
2675
2676 default:
2677 fatal("BarrierSet resolving not implemented");
2678 };
2679 }
2680
2681 template <bool use_compressed, typename BarrierSetT>
2682 static void resolve() {
2683 typedef Config<use_compressed ? oop_kind::NARROW : oop_kind::WIDE, BarrierSetT> SelectedConfigT;
2684
2685 freeze_entry = (address)freeze<SelectedConfigT>;
2686
2687 // If we wanted, we could templatize by kind and have three different thaw entries
2688 thaw_entry = (address)thaw<SelectedConfigT>;
2689 }
2690 };
2691
2692 void Continuation::init() {
2693 ConfigResolve::resolve();
2694 }