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/objectMonitor.inline.hpp"
59 #include "runtime/orderAccess.hpp"
60 #include "runtime/prefetch.inline.hpp"
61 #include "runtime/smallRegisterMap.inline.hpp"
62 #include "runtime/sharedRuntime.hpp"
63 #include "runtime/stackChunkFrameStream.inline.hpp"
64 #include "runtime/stackFrameStream.inline.hpp"
65 #include "runtime/stackOverflow.hpp"
66 #include "runtime/stackWatermarkSet.inline.hpp"
67 #include "utilities/debug.hpp"
68 #include "utilities/exceptions.hpp"
69 #include "utilities/macros.hpp"
70 #include "utilities/vmError.hpp"
71 #if INCLUDE_ZGC
72 #include "gc/z/zStackChunkGCData.inline.hpp"
73 #endif
74
75 #include <type_traits>
76
77 /*
78 * This file contains the implementation of continuation freezing (yield) and thawing (run).
79 *
80 * This code is very latency-critical and very hot. An ordinary and well-behaved server application
81 * would likely call these operations many thousands of times per second second, on every core.
82 *
83 * Freeze might be called every time the application performs any I/O operation, every time it
84 * acquires a j.u.c. lock, every time it takes a message from a queue, and thaw can be called
85 * multiple times in each of those cases, as it is called by the return barrier, which may be
86 * invoked on method return.
87 *
88 * The amortized budget for each of those two operations is ~100-150ns. That is why, for
89 * example, every effort is made to avoid Java-VM transitions as much as possible.
90 *
91 * On the fast path, all frames are known to be compiled, and the chunk requires no barriers
92 * and so frames simply copied, and the bottom-most one is patched.
93 * On the slow path, internal pointers in interpreted frames are de/relativized to/from offsets
94 * and absolute pointers, and barriers invoked.
95 */
96
97 /************************************************
98
99 Thread-stack layout on freeze/thaw.
100 See corresponding stack-chunk layout in instanceStackChunkKlass.hpp
101
102 +----------------------------+
103 | . |
104 | . |
105 | . |
106 | carrier frames |
107 | |
108 |----------------------------|
109 | |
110 | Continuation.run |
111 | |
112 |============================|
113 | enterSpecial frame |
114 | pc |
115 | rbp |
116 | ----- |
117 ^ | int argsize | = ContinuationEntry
118 | | oopDesc* cont |
119 | | oopDesc* chunk |
120 | | ContinuationEntry* parent |
121 | | ... |
122 | |============================| <------ JavaThread::_cont_entry = entry->sp()
123 | | ? alignment word ? |
124 | |----------------------------| <--\
125 | | | |
126 | | ? caller stack args ? | | argsize (might not be 2-word aligned) words
127 Address | | | | Caller is still in the chunk.
128 | |----------------------------| |
129 | | pc (? return barrier ?) | | This pc contains the return barrier when the bottom-most frame
130 | | rbp | | isn't the last one in the continuation.
131 | | | |
132 | | frame | |
133 | | | |
134 +----------------------------| \__ Continuation frames to be frozen/thawed
135 | | /
136 | frame | |
137 | | |
138 |----------------------------| |
139 | | |
140 | frame | |
141 | | |
142 |----------------------------| <--/
143 | |
144 | doYield/safepoint stub | When preempting forcefully, we could have a safepoint stub
145 | | instead of a doYield stub
146 |============================| <- the sp passed to freeze
147 | |
148 | Native freeze/thaw frames |
149 | . |
150 | . |
151 | . |
152 +----------------------------+
153
154 ************************************************/
155
156 static const bool TEST_THAW_ONE_CHUNK_FRAME = false; // force thawing frames one-at-a-time for testing
157
158 #define CONT_JFR false // emit low-level JFR events that count slow/fast path for continuation performance debugging only
159 #if CONT_JFR
160 #define CONT_JFR_ONLY(code) code
161 #else
162 #define CONT_JFR_ONLY(code)
163 #endif
164
165 // TODO: See AbstractAssembler::generate_stack_overflow_check,
166 // Compile::bang_size_in_bytes(), m->as_SafePoint()->jvms()->interpreter_frame_size()
167 // when we stack-bang, we need to update a thread field with the lowest (farthest) bang point.
168
169 // Data invariants are defined by Continuation::debug_verify_continuation and Continuation::debug_verify_stack_chunk
170
171 // Used to just annotatate cold/hot branches
172 #define LIKELY(condition) (condition)
173 #define UNLIKELY(condition) (condition)
174
175 // debugging functions
176 #ifdef ASSERT
177 extern "C" bool dbg_is_safe(const void* p, intptr_t errvalue); // address p is readable and *(intptr_t*)p != errvalue
178
179 static void verify_continuation(oop continuation) { Continuation::debug_verify_continuation(continuation); }
180
181 static void do_deopt_after_thaw(JavaThread* thread);
182 static bool do_verify_after_thaw(JavaThread* thread, stackChunkOop chunk, outputStream* st);
183 static void log_frames(JavaThread* thread);
184 static void log_frames_after_thaw(JavaThread* thread, ContinuationWrapper& cont, intptr_t* sp);
185 static void print_frame_layout(const frame& f, bool callee_complete, outputStream* st = tty);
186
187 #define assert_pfl(p, ...) \
188 do { \
189 if (!(p)) { \
190 JavaThread* t = JavaThread::active(); \
191 if (t->has_last_Java_frame()) { \
192 tty->print_cr("assert(" #p ") failed:"); \
193 t->print_frame_layout(); \
194 } \
195 } \
196 vmassert(p, __VA_ARGS__); \
197 } while(0)
198
199 #else
200 static void verify_continuation(oop continuation) { }
201 #define assert_pfl(p, ...)
202 #endif
203
204 static freeze_result is_pinned0(JavaThread* thread, oop cont_scope, bool safepoint);
205 template<typename ConfigT, bool preempt> static inline int freeze_internal(JavaThread* thread, intptr_t* const sp, int freeze_kind = freeze_self_from_java);
206
207 static inline int prepare_thaw_internal(JavaThread* thread, bool return_barrier);
208 template<typename ConfigT> static inline intptr_t* thaw_internal(JavaThread* thread, const Continuation::thaw_kind kind);
209
210
211 // Entry point to freeze. Transitions are handled manually
212 // Called from gen_continuation_yield() in sharedRuntime_<cpu>.cpp through Continuation::freeze_entry();
213 template<typename ConfigT>
214 static JRT_BLOCK_ENTRY(int, freeze(JavaThread* current, intptr_t* sp))
215 assert(sp == current->frame_anchor()->last_Java_sp(), "");
216
217 if (current->raw_cont_fastpath() > current->last_continuation()->entry_sp() || current->raw_cont_fastpath() < sp) {
218 current->set_cont_fastpath(nullptr);
219 }
220
221 return ConfigT::freeze(current, sp);
222 JRT_END
223
224 JRT_LEAF(int, Continuation::prepare_thaw(JavaThread* thread, bool return_barrier))
225 return prepare_thaw_internal(thread, return_barrier);
226 JRT_END
227
228 template<typename ConfigT>
229 static JRT_LEAF(intptr_t*, thaw(JavaThread* thread, int kind))
230 // TODO: JRT_LEAF and NoHandleMark is problematic for JFR events.
231 // vFrameStreamCommon allocates Handles in RegisterMap for continuations.
232 // Also the preemption case with JVMTI events enabled might safepoint so
233 // undo the NoSafepointVerifier here and rely on handling by ContinuationWrapper.
234 // JRT_ENTRY instead?
235 ResetNoHandleMark rnhm;
236 debug_only(PauseNoSafepointVerifier pnsv(&__nsv);)
237
238 // we might modify the code cache via BarrierSetNMethod::nmethod_entry_barrier
239 MACOS_AARCH64_ONLY(ThreadWXEnable __wx(WXWrite, thread));
240 return ConfigT::thaw(thread, (Continuation::thaw_kind)kind);
241 JRT_END
242
243 JVM_ENTRY(jint, CONT_isPinned0(JNIEnv* env, jobject cont_scope)) {
244 JavaThread* thread = JavaThread::thread_from_jni_environment(env);
245 return is_pinned0(thread, JNIHandles::resolve(cont_scope), false);
246 }
247 JVM_END
248
249 ///////////
250
251 enum class oop_kind { NARROW, WIDE };
252 template <oop_kind oops, typename BarrierSetT>
253 class Config {
254 public:
255 typedef Config<oops, BarrierSetT> SelfT;
256 using OopT = std::conditional_t<oops == oop_kind::NARROW, narrowOop, oop>;
257
258 static int freeze(JavaThread* thread, intptr_t* const sp) {
259 return freeze_internal<SelfT, false>(thread, sp);
260 }
261
262 static int freeze_preempt(JavaThread* thread, intptr_t* const sp, int preempt_kind) {
263 return freeze_internal<SelfT, true>(thread, sp, preempt_kind);
264 }
265
266 static intptr_t* thaw(JavaThread* thread, Continuation::thaw_kind kind) {
267 return thaw_internal<SelfT>(thread, kind);
268 }
269 };
270
271 static bool stack_overflow_check(JavaThread* thread, size_t size, address sp) {
272 const size_t page_size = os::vm_page_size();
273 if (size > page_size) {
274 if (sp - size < thread->stack_overflow_state()->shadow_zone_safe_limit()) {
275 return false;
276 }
277 }
278 return true;
279 }
280
281 #ifdef ASSERT
282 static oop get_continuation(JavaThread* thread) {
283 assert(thread != nullptr, "");
284 assert(thread->threadObj() != nullptr, "");
285 return java_lang_Thread::continuation(thread->threadObj());
286 }
287 #endif // ASSERT
288
289 inline void clear_anchor(JavaThread* thread) {
290 thread->frame_anchor()->clear();
291 }
292
293 static void set_anchor(JavaThread* thread, intptr_t* sp, address pc = nullptr) {
294 if (pc == nullptr) {
295 pc = ContinuationHelper::return_address_at(
296 sp - frame::sender_sp_ret_address_offset());
297 }
298 assert(pc != nullptr, "");
299
300 JavaFrameAnchor* anchor = thread->frame_anchor();
301 anchor->set_last_Java_sp(sp);
302 anchor->set_last_Java_pc(pc);
303 ContinuationHelper::set_anchor_pd(anchor, sp);
304
305 assert(thread->has_last_Java_frame(), "");
306 assert(thread->last_frame().cb() != nullptr, "");
307 }
308
309 static void set_anchor_to_entry(JavaThread* thread, ContinuationEntry* entry) {
310 JavaFrameAnchor* anchor = thread->frame_anchor();
311 anchor->set_last_Java_sp(entry->entry_sp());
312 anchor->set_last_Java_pc(entry->entry_pc());
313 ContinuationHelper::set_anchor_to_entry_pd(anchor, entry);
314
315 assert(thread->has_last_Java_frame(), "");
316 assert(thread->last_frame().cb() != nullptr, "");
317 }
318
319 #ifdef ASSERT
320 static int monitors_to_fix_on_stack(JavaThread* thread) {
321 ResourceMark rm(JavaThread::current());
322 ContinuationEntry* ce = thread->last_continuation();
323 RegisterMap map(thread,
324 RegisterMap::UpdateMap::include,
325 RegisterMap::ProcessFrames::include,
326 RegisterMap::WalkContinuation::include);
327 map.set_include_argument_oops(false);
328 ResourceHashtable<oopDesc*, bool> rhtable;
329 int monitor_count = 0;
330 for (frame f = thread->last_frame(); Continuation::is_frame_in_continuation(thread, f); f = f.sender(&map)) {
331 if (f.is_interpreted_frame()) {
332 frame abs = !f.is_heap_frame() ? f : map.stack_chunk()->derelativize(f);
333 monitor_count += ContinuationHelper::InterpretedFrame::monitors_to_fix(thread, abs, rhtable, map.stack_chunk()());
334 } else if (f.is_compiled_frame()) {
335 monitor_count += ContinuationHelper::CompiledFrame::monitors_to_fix(thread, &map, f, rhtable);
336 } else if (f.is_native_frame()) {
337 monitor_count += ContinuationHelper::NativeFrame::monitors_to_fix(thread, f, rhtable);
338 }
339 }
340 return monitor_count;
341 }
342 #endif
343
344 #if CONT_JFR
345 class FreezeThawJfrInfo : public StackObj {
346 short _e_size;
347 short _e_num_interpreted_frames;
348 public:
349
350 FreezeThawJfrInfo() : _e_size(0), _e_num_interpreted_frames(0) {}
351 inline void record_interpreted_frame() { _e_num_interpreted_frames++; }
352 inline void record_size_copied(int size) { _e_size += size << LogBytesPerWord; }
353 template<typename Event> void post_jfr_event(Event *e, oop continuation, JavaThread* jt);
354 };
355
356 template<typename Event> void FreezeThawJfrInfo::post_jfr_event(Event* e, oop continuation, JavaThread* jt) {
357 if (e->should_commit()) {
358 log_develop_trace(continuations)("JFR event: iframes: %d size: %d", _e_num_interpreted_frames, _e_size);
359 e->set_carrierThread(JFR_JVM_THREAD_ID(jt));
360 e->set_continuationClass(continuation->klass());
361 e->set_interpretedFrames(_e_num_interpreted_frames);
362 e->set_size(_e_size);
363 e->commit();
364 }
365 }
366 #endif // CONT_JFR
367
368 /////////////// FREEZE ////
369
370 class FreezeBase : public StackObj {
371 protected:
372 JavaThread* const _thread;
373 ContinuationWrapper& _cont;
374 bool _barriers; // only set when we allocate a chunk
375
376 intptr_t* _bottom_address;
377
378 const bool _preempt;
379 // Used on preemption only
380 frame _last_frame;
381 oop _monitorenter_obj;
382
383 // Used to support freezing with held monitors
384 int _monitors_to_fix;
385 int _monitors_in_lockstack;
386
387 int _freeze_size; // total size of all frames plus metadata in words.
388 int _total_align_size;
389
390 intptr_t* _cont_stack_top;
391 intptr_t* _cont_stack_bottom;
392
393 CONT_JFR_ONLY(FreezeThawJfrInfo _jfr_info;)
394
395 #ifdef ASSERT
396 intptr_t* _orig_chunk_sp;
397 int _fast_freeze_size;
398 bool _empty;
399 #endif
400
401 JvmtiSampledObjectAllocEventCollector* _jvmti_event_collector;
402
403 NOT_PRODUCT(int _frames;)
404 DEBUG_ONLY(intptr_t* _last_write;)
405
406 inline FreezeBase(JavaThread* thread, ContinuationWrapper& cont, intptr_t* sp, bool preempt);
407
408 public:
409 NOINLINE freeze_result freeze_slow();
410 void freeze_fast_existing_chunk();
411
412 CONT_JFR_ONLY(FreezeThawJfrInfo& jfr_info() { return _jfr_info; })
413 void set_jvmti_event_collector(JvmtiSampledObjectAllocEventCollector* jsoaec) { _jvmti_event_collector = jsoaec; }
414
415 inline int size_if_fast_freeze_available();
416
417 inline frame& last_frame() { return _last_frame; }
418
419 #ifdef ASSERT
420 bool check_valid_fast_path();
421 #endif
422
423 protected:
424 inline void init_rest();
425 void throw_stack_overflow_on_humongous_chunk();
426
427 // fast path
428 inline void copy_to_chunk(intptr_t* from, intptr_t* to, int size);
429 inline void unwind_frames();
430 inline void patch_stack_pd(intptr_t* frame_sp, intptr_t* heap_sp);
431
432 // slow path
433 virtual stackChunkOop allocate_chunk_slow(size_t stack_size, int argsize_md) = 0;
434
435 int cont_size() { return pointer_delta_as_int(_cont_stack_bottom, _cont_stack_top); }
436
437 private:
438 // slow path
439 frame freeze_start_frame();
440 frame freeze_start_frame_on_preempt();
441 NOINLINE freeze_result recurse_freeze(frame& f, frame& caller, int callee_argsize, bool callee_interpreted, bool top);
442 inline frame freeze_start_frame_yield_stub();
443 template<typename FKind>
444 inline freeze_result recurse_freeze_java_frame(const frame& f, frame& caller, int fsize, int argsize);
445 inline void before_freeze_java_frame(const frame& f, const frame& caller, int fsize, int argsize, bool is_bottom_frame);
446 inline void after_freeze_java_frame(const frame& hf, bool is_bottom_frame);
447 freeze_result finalize_freeze(const frame& callee, frame& caller, int argsize);
448 void patch(const frame& f, frame& hf, const frame& caller, bool is_bottom_frame);
449 NOINLINE freeze_result recurse_freeze_interpreted_frame(frame& f, frame& caller, int callee_argsize, bool callee_interpreted);
450 freeze_result recurse_freeze_compiled_frame(frame& f, frame& caller, int callee_argsize, bool callee_interpreted);
451 NOINLINE freeze_result recurse_freeze_stub_frame(frame& f, frame& caller);
452 NOINLINE freeze_result recurse_freeze_native_frame(frame& f, frame& caller);
453 NOINLINE void finish_freeze(const frame& f, const frame& top);
454
455 void fix_monitors_in_interpreted_frame(frame& f);
456 template <typename RegisterMapT>
457 void fix_monitors_in_compiled_frame(frame& f, RegisterMapT* map);
458 void fix_monitors_in_fast_path();
459
460 inline bool stack_overflow();
461
462 static frame sender(const frame& f) { return f.is_interpreted_frame() ? sender<ContinuationHelper::InterpretedFrame>(f)
463 : sender<ContinuationHelper::NonInterpretedUnknownFrame>(f); }
464 template<typename FKind> static inline frame sender(const frame& f);
465 template<typename FKind> frame new_heap_frame(frame& f, frame& caller);
466 inline void set_top_frame_metadata_pd(const frame& hf);
467 inline void patch_pd(frame& callee, const frame& caller);
468 void adjust_interpreted_frame_unextended_sp(frame& f);
469 static inline void prepare_freeze_interpreted_top_frame(const frame& f);
470 static inline void relativize_interpreted_frame_metadata(const frame& f, const frame& hf);
471
472 protected:
473 void freeze_fast_copy(stackChunkOop chunk, int chunk_start_sp CONT_JFR_ONLY(COMMA bool chunk_is_allocated));
474 bool freeze_fast_new_chunk(stackChunkOop chunk);
475 };
476
477 template <typename ConfigT>
478 class Freeze : public FreezeBase {
479 private:
480 stackChunkOop allocate_chunk(size_t stack_size, int argsize_md);
481
482 public:
483 inline Freeze(JavaThread* thread, ContinuationWrapper& cont, intptr_t* frame_sp, bool preempt)
484 : FreezeBase(thread, cont, frame_sp, preempt) {}
485
486 freeze_result try_freeze_fast();
487
488 protected:
489 virtual stackChunkOop allocate_chunk_slow(size_t stack_size, int argsize_md) override { return allocate_chunk(stack_size, argsize_md); }
490 };
491
492 FreezeBase::FreezeBase(JavaThread* thread, ContinuationWrapper& cont, intptr_t* frame_sp, bool preempt) :
493 _thread(thread), _cont(cont), _barriers(false), _preempt(preempt), _last_frame(false /* no initialization */) {
494 DEBUG_ONLY(_jvmti_event_collector = nullptr;)
495
496 assert(_thread != nullptr, "");
497 assert(_thread->last_continuation()->entry_sp() == _cont.entrySP(), "");
498
499 DEBUG_ONLY(_cont.entry()->verify_cookie();)
500
501 assert(!Interpreter::contains(_cont.entryPC()), "");
502
503 _bottom_address = _cont.entrySP() - _cont.entry_frame_extension();
504 #ifdef _LP64
505 if (((intptr_t)_bottom_address & 0xf) != 0) {
506 _bottom_address--;
507 }
508 assert(is_aligned(_bottom_address, frame::frame_alignment), "");
509 #endif
510
511 log_develop_trace(continuations)("bottom_address: " INTPTR_FORMAT " entrySP: " INTPTR_FORMAT " argsize: " PTR_FORMAT,
512 p2i(_bottom_address), p2i(_cont.entrySP()), (_cont.entrySP() - _bottom_address) << LogBytesPerWord);
513 assert(_bottom_address != nullptr, "");
514 assert(_bottom_address <= _cont.entrySP(), "");
515 DEBUG_ONLY(_last_write = nullptr;)
516
517 assert(_cont.chunk_invariant(), "");
518 assert(!Interpreter::contains(_cont.entryPC()), "");
519 #if !defined(PPC64) || defined(ZERO)
520 static const int doYield_stub_frame_size = frame::metadata_words;
521 #else
522 static const int doYield_stub_frame_size = frame::native_abi_reg_args_size >> LogBytesPerWord;
523 #endif
524 // With preemption doYield() might not have been resolved yet
525 assert(_preempt || SharedRuntime::cont_doYield_stub()->frame_size() == doYield_stub_frame_size, "");
526
527 if (preempt) {
528 _last_frame = _thread->last_frame();
529 }
530
531 // properties of the continuation on the stack; all sizes are in words
532 _cont_stack_top = frame_sp + (!preempt ? doYield_stub_frame_size : 0); // we don't freeze the doYield stub frame
533 _cont_stack_bottom = _cont.entrySP() + (_cont.argsize() == 0 ? frame::metadata_words_at_top : 0)
534 - ContinuationHelper::frame_align_words(_cont.argsize()); // see alignment in thaw
535
536 log_develop_trace(continuations)("freeze size: %d argsize: %d top: " INTPTR_FORMAT " bottom: " INTPTR_FORMAT,
537 cont_size(), _cont.argsize(), p2i(_cont_stack_top), p2i(_cont_stack_bottom));
538 assert(cont_size() > 0, "");
539
540 if (LockingMode == LM_LEGACY) {
541 _monitors_to_fix = thread->held_monitor_count();
542 assert(_monitors_to_fix >= 0, "invariant");
543 _monitors_in_lockstack = 0;
544 assert(_thread->lock_stack().monitor_count() == 0, "should be set only for LM_LIGHTWEIGHT");
545 } else {
546 _monitors_in_lockstack = _thread->lock_stack().monitor_count();
547 assert(_monitors_in_lockstack >= 0 && _monitors_in_lockstack <= 8, "_monitors_in_lockstack=%d", _monitors_in_lockstack);
548 _monitors_to_fix = _monitors_in_lockstack;
549 assert(thread->held_monitor_count() == 0, "should be set only for LM_LEGACY");
550 }
551 DEBUG_ONLY(int verified_cnt = monitors_to_fix_on_stack(_thread);)
552 assert(verified_cnt == _monitors_to_fix || thread->obj_locker_count() > 0 ||
553 (LockingMode == LM_LIGHTWEIGHT && verified_cnt == _thread->lock_stack().unique_count()),
554 "wrong monitor count. Found %d in the stack but counter is %d", verified_cnt, _monitors_to_fix);
555 }
556
557 void FreezeBase::init_rest() { // we want to postpone some initialization after chunk handling
558 _freeze_size = 0;
559 _total_align_size = 0;
560 NOT_PRODUCT(_frames = 0;)
561 }
562
563 void FreezeBase::fix_monitors_in_interpreted_frame(frame& f) {
564 assert(LockingMode == LM_LEGACY, "invariant");
565 BasicObjectLock* first_mon = f.interpreter_frame_monitor_begin();
566 BasicObjectLock* last_mon = f.interpreter_frame_monitor_end();
567 assert(last_mon <= first_mon, "must be");
568
569 if (first_mon == last_mon) {
570 // No monitors in this frame
571 return;
572 }
573
574 for (BasicObjectLock* current = f.previous_monitor_in_interpreter_frame(first_mon);
575 current >= last_mon; current = f.previous_monitor_in_interpreter_frame(current)) {
576 oop obj = current->obj();
577 if (obj == nullptr) {
578 continue;
579 }
580 if (obj == _monitorenter_obj) {
581 assert(_preempt, "should be preemption on monitorenter case");
582 assert(obj->mark().monitor() != nullptr, "failed to acquire the lock but its not inflated");
583 continue;
584 }
585 markWord mark = obj->mark();
586 if (mark.has_monitor() && !mark.monitor()->is_owner_anonymous()) {
587 // Good for freezing, nothing to do.
588 assert(mark.monitor()->is_owner(_thread), "invariant");
589 continue;
590 }
591 // Found locked monitor that needs fixing. Inflate will fix the owner for stack-locked case or inflated but anonymously owned.
592 ObjectMonitor* om = ObjectSynchronizer::inflate(_thread, obj, ObjectSynchronizer::InflateCause::inflate_cause_cont_freeze);
593 assert(om != nullptr, "invariant");
594 assert(om->is_owner(_thread), "invariant");
595 if (--_monitors_to_fix == 0) break;
596 }
597 assert(_monitors_to_fix >= 0, "invariant");
598 }
599
600 template <typename RegisterMapT>
601 void FreezeBase::fix_monitors_in_compiled_frame(frame& f, RegisterMapT* map) {
602 assert(LockingMode == LM_LEGACY, "invariant");
603 assert(!f.is_interpreted_frame(), "");
604 assert(ContinuationHelper::CompiledFrame::is_instance(f), "");
605
606 nmethod* nm = f.cb()->as_nmethod();
607
608 if (!nm->has_monitors()) {
609 // No monitors in this frame
610 return;
611 }
612
613 for (ScopeDesc* scope = nm->scope_desc_at(f.pc()); scope != nullptr; scope = scope->sender()) {
614 GrowableArray<MonitorValue*>* mons = scope->monitors();
615 if (mons == nullptr || mons->is_empty()) {
616 continue;
617 }
618
619 for (int index = (mons->length()-1); index >= 0; index--) { // see compiledVFrame::monitors()
620 MonitorValue* mon = mons->at(index);
621 if (mon->eliminated()) {
622 continue; // we ignore eliminated monitors
623 }
624 ScopeValue* ov = mon->owner();
625 StackValue* owner_sv = StackValue::create_stack_value(&f, map, ov); // it is an oop
626 oop obj = owner_sv->get_obj()();
627 if (obj == nullptr) {
628 continue;
629 }
630 if (obj == _monitorenter_obj) {
631 assert(_preempt, "should be preemption on monitorenter case");
632 assert(obj->mark().monitor() != nullptr, "failed to acquire the lock but its not inflated");
633 continue;
634 }
635 markWord mark = obj->mark();
636 if (mark.has_monitor() && !mark.monitor()->is_owner_anonymous()) {
637 // Good for freezing, nothing to do.
638 assert(mark.monitor()->is_owner(_thread), "invariant");
639 continue;
640 }
641 // Found locked monitor that needs fixing. Inflate will fix the owner for stack-locked case or inflated but anonymously owned.
642 ObjectMonitor* om = ObjectSynchronizer::inflate(_thread, obj, ObjectSynchronizer::InflateCause::inflate_cause_cont_freeze);
643 assert(om != nullptr, "invariant");
644 assert(om->is_owner(_thread), "invariant");
645 if (--_monitors_to_fix == 0) break;
646 }
647 }
648 assert(_monitors_to_fix >= 0, "invariant");
649 }
650
651 void FreezeBase::fix_monitors_in_fast_path() {
652 if (LockingMode == LM_LIGHTWEIGHT) {
653 stackChunkOop chunk = _cont.tail();
654 assert(chunk->sp_address() - chunk->start_address() >= _monitors_in_lockstack, "no room for lockstack");
655 _thread->lock_stack().move_to_address((oop*)chunk->start_address());
656
657 chunk->set_lockstack_size((uint8_t)_monitors_in_lockstack);
658 chunk->set_has_lockstack(true);
659
660 DEBUG_ONLY(_monitors_to_fix -= _monitors_in_lockstack;)
661 } else {
662 assert(LockingMode == LM_LEGACY, "invariant");
663 _monitorenter_obj = _thread->is_on_monitorenter() ? _thread->current_pending_monitor()->object() : nullptr;
664
665 ResourceMark rm(_thread);
666 RegisterMap map(JavaThread::current(),
667 RegisterMap::UpdateMap::include,
668 RegisterMap::ProcessFrames::skip, // already processed in unwind_frames()
669 RegisterMap::WalkContinuation::skip);
670 map.set_include_argument_oops(false);
671 frame freezed_top(_cont_stack_top);
672 frame first = !_preempt ? freezed_top : freezed_top.sender(&map);
673 for (frame f = first; _monitors_to_fix > 0 && Continuation::is_frame_in_continuation(_cont.entry(), f); f = f.sender(&map)) {
674 fix_monitors_in_compiled_frame(f, &map);
675 }
676 }
677 assert(_monitors_to_fix == 0, "missing monitors in stack");
678 assert(_thread->held_monitor_count() == 0, "should be 0 now");
679 }
680
681 void FreezeBase::copy_to_chunk(intptr_t* from, intptr_t* to, int size) {
682 stackChunkOop chunk = _cont.tail();
683 chunk->copy_from_stack_to_chunk(from, to, size);
684 CONT_JFR_ONLY(_jfr_info.record_size_copied(size);)
685
686 #ifdef ASSERT
687 if (_last_write != nullptr) {
688 assert(_last_write == to + size, "Missed a spot: _last_write: " INTPTR_FORMAT " to+size: " INTPTR_FORMAT
689 " stack_size: %d _last_write offset: " PTR_FORMAT " to+size: " PTR_FORMAT, p2i(_last_write), p2i(to+size),
690 chunk->stack_size(), _last_write-chunk->start_address(), to+size-chunk->start_address());
691 _last_write = to;
692 }
693 #endif
694 }
695
696 // Called _after_ the last possible safepoint during the freeze operation (chunk allocation)
697 void FreezeBase::unwind_frames() {
698 ContinuationEntry* entry = _cont.entry();
699 entry->flush_stack_processing(_thread);
700 set_anchor_to_entry(_thread, entry);
701 }
702
703 template <typename ConfigT>
704 freeze_result Freeze<ConfigT>::try_freeze_fast() {
705 assert(_thread->thread_state() == _thread_in_vm, "");
706 assert(_thread->cont_fastpath(), "");
707
708 DEBUG_ONLY(_fast_freeze_size = size_if_fast_freeze_available();)
709 assert(_fast_freeze_size == 0, "");
710
711 stackChunkOop chunk = allocate_chunk(cont_size() + frame::metadata_words + _monitors_in_lockstack, _cont.argsize() + frame::metadata_words_at_top);
712 if (freeze_fast_new_chunk(chunk)) {
713 return freeze_ok;
714 }
715 if (_thread->has_pending_exception()) {
716 return freeze_exception;
717 }
718
719 // TODO R REMOVE when deopt change is fixed
720 assert(!_thread->cont_fastpath() || _barriers, "");
721 log_develop_trace(continuations)("-- RETRYING SLOW --");
722 return freeze_slow();
723 }
724
725 // Returns size needed if the continuation fits, otherwise 0.
726 int FreezeBase::size_if_fast_freeze_available() {
727 stackChunkOop chunk = _cont.tail();
728 if (chunk == nullptr || chunk->is_gc_mode() || chunk->requires_barriers() || chunk->has_mixed_frames()) {
729 log_develop_trace(continuations)("chunk available %s", chunk == nullptr ? "no chunk" : "chunk requires barriers");
730 return 0;
731 }
732
733 int total_size_needed = cont_size();
734 const int chunk_sp = chunk->sp();
735
736 // argsize can be nonzero if we have a caller, but the caller could be in a non-empty parent chunk,
737 // so we subtract it only if we overlap with the caller, i.e. the current chunk isn't empty.
738 // Consider leaving the chunk's argsize set when emptying it and removing the following branch,
739 // although that would require changing stackChunkOopDesc::is_empty
740 if (!chunk->is_empty()) {
741 total_size_needed -= _cont.argsize() + frame::metadata_words_at_top;
742 }
743
744 total_size_needed += _monitors_in_lockstack;
745
746 int chunk_free_room = chunk_sp - frame::metadata_words_at_bottom;
747 bool available = chunk_free_room >= total_size_needed;
748 log_develop_trace(continuations)("chunk available: %s size: %d argsize: %d top: " INTPTR_FORMAT " bottom: " INTPTR_FORMAT,
749 available ? "yes" : "no" , total_size_needed, _cont.argsize(), p2i(_cont_stack_top), p2i(_cont_stack_bottom));
750 return available ? total_size_needed : 0;
751 }
752
753 void FreezeBase::freeze_fast_existing_chunk() {
754 stackChunkOop chunk = _cont.tail();
755
756 DEBUG_ONLY(_fast_freeze_size = size_if_fast_freeze_available();)
757 assert(_fast_freeze_size > 0, "");
758
759 if (!chunk->is_empty()) { // we are copying into a non-empty chunk
760 DEBUG_ONLY(_empty = false;)
761 DEBUG_ONLY(_orig_chunk_sp = chunk->sp_address();)
762 #ifdef ASSERT
763 {
764 intptr_t* retaddr_slot = (chunk->sp_address()
765 - frame::sender_sp_ret_address_offset());
766 assert(ContinuationHelper::return_address_at(retaddr_slot) == chunk->pc(),
767 "unexpected saved return address");
768 }
769 #endif
770
771 // the chunk's sp before the freeze, adjusted to point beyond the stack-passed arguments in the topmost frame
772 // we overlap; we'll overwrite the chunk's top frame's callee arguments
773 const int chunk_start_sp = chunk->sp() + _cont.argsize() + frame::metadata_words_at_top;
774 assert(chunk_start_sp <= chunk->stack_size(), "sp not pointing into stack");
775
776 // increase max_size by what we're freezing minus the overlap
777 chunk->set_max_thawing_size(chunk->max_thawing_size() + cont_size() - _cont.argsize() - frame::metadata_words_at_top);
778
779 intptr_t* const bottom_sp = _cont_stack_bottom - _cont.argsize() - frame::metadata_words_at_top;
780 assert(bottom_sp == _bottom_address, "");
781 // Because the chunk isn't empty, we know there's a caller in the chunk, therefore the bottom-most frame
782 // should have a return barrier (installed back when we thawed it).
783 #ifdef ASSERT
784 {
785 intptr_t* retaddr_slot = (bottom_sp
786 - frame::sender_sp_ret_address_offset());
787 assert(ContinuationHelper::return_address_at(retaddr_slot)
788 == StubRoutines::cont_returnBarrier(),
789 "should be the continuation return barrier");
790 }
791 #endif
792 // We copy the fp from the chunk back to the stack because it contains some caller data,
793 // including, possibly, an oop that might have gone stale since we thawed.
794 patch_stack_pd(bottom_sp, chunk->sp_address());
795 // we don't patch the return pc at this time, so as not to make the stack unwalkable for async walks
796
797 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA false));
798 } else { // the chunk is empty
799 const int chunk_start_sp = chunk->stack_size();
800
801 DEBUG_ONLY(_empty = true;)
802 DEBUG_ONLY(_orig_chunk_sp = chunk->start_address() + chunk_start_sp;)
803
804 chunk->set_max_thawing_size(cont_size());
805 chunk->set_bottom(chunk_start_sp - _cont.argsize() - frame::metadata_words_at_top);
806 chunk->set_sp(chunk->bottom());
807
808 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA false));
809 }
810 }
811
812 bool FreezeBase::freeze_fast_new_chunk(stackChunkOop chunk) {
813 DEBUG_ONLY(_empty = true;)
814
815 // Install new chunk
816 _cont.set_tail(chunk);
817
818 if (UNLIKELY(chunk == nullptr || !_thread->cont_fastpath() || _barriers)) { // OOME/probably humongous
819 log_develop_trace(continuations)("Retrying slow. Barriers: %d", _barriers);
820 return false;
821 }
822
823 chunk->set_max_thawing_size(cont_size());
824
825 // in a fresh chunk, we freeze *with* the bottom-most frame's stack arguments.
826 // They'll then be stored twice: in the chunk and in the parent chunk's top frame
827 const int chunk_start_sp = cont_size() + frame::metadata_words + _monitors_in_lockstack;
828 assert(chunk_start_sp == chunk->stack_size(), "");
829
830 DEBUG_ONLY(_orig_chunk_sp = chunk->start_address() + chunk_start_sp;)
831
832 freeze_fast_copy(chunk, chunk_start_sp CONT_JFR_ONLY(COMMA true));
833
834 return true;
835 }
836
837 void FreezeBase::freeze_fast_copy(stackChunkOop chunk, int chunk_start_sp CONT_JFR_ONLY(COMMA bool chunk_is_allocated)) {
838 assert(chunk != nullptr, "");
839 assert(!chunk->has_mixed_frames(), "");
840 assert(!chunk->is_gc_mode(), "");
841 assert(!chunk->has_bitmap(), "");
842 assert(!chunk->requires_barriers(), "");
843 assert(chunk == _cont.tail(), "");
844
845 // We unwind frames after the last safepoint so that the GC will have found the oops in the frames, but before
846 // writing into the chunk. This is so that an asynchronous stack walk (not at a safepoint) that suspends us here
847 // will either see no continuation on the stack, or a consistent chunk.
848 unwind_frames();
849
850 log_develop_trace(continuations)("freeze_fast start: chunk " INTPTR_FORMAT " size: %d orig sp: %d argsize: %d",
851 p2i((oopDesc*)chunk), chunk->stack_size(), chunk_start_sp, _cont.argsize());
852 assert(chunk_start_sp <= chunk->stack_size(), "");
853 assert(chunk_start_sp >= cont_size(), "no room in the chunk");
854
855 const int chunk_new_sp = chunk_start_sp - cont_size(); // the chunk's new sp, after freeze
856 assert(!(_fast_freeze_size > 0) || (_orig_chunk_sp - (chunk->start_address() + chunk_new_sp)) == (_fast_freeze_size - _monitors_in_lockstack), "");
857
858 intptr_t* chunk_top = chunk->start_address() + chunk_new_sp;
859 #ifdef ASSERT
860 if (!_empty) {
861 intptr_t* retaddr_slot = (_orig_chunk_sp
862 - frame::sender_sp_ret_address_offset());
863 assert(ContinuationHelper::return_address_at(retaddr_slot) == chunk->pc(),
864 "unexpected saved return address");
865 }
866 #endif
867
868 log_develop_trace(continuations)("freeze_fast start: " INTPTR_FORMAT " sp: %d chunk_top: " INTPTR_FORMAT,
869 p2i(chunk->start_address()), chunk_new_sp, p2i(chunk_top));
870 intptr_t* from = _cont_stack_top - frame::metadata_words_at_bottom;
871 intptr_t* to = chunk_top - frame::metadata_words_at_bottom;
872 copy_to_chunk(from, to, cont_size() + frame::metadata_words_at_bottom);
873 // Because we're not patched yet, the chunk is now in a bad state
874
875 // patch return pc of the bottom-most frozen frame (now in the chunk)
876 // with the actual caller's return address
877 intptr_t* chunk_bottom_retaddr_slot = (chunk_top + cont_size()
878 - _cont.argsize()
879 - frame::metadata_words_at_top
880 - frame::sender_sp_ret_address_offset());
881 #ifdef ASSERT
882 if (!_empty) {
883 assert(ContinuationHelper::return_address_at(chunk_bottom_retaddr_slot)
884 == StubRoutines::cont_returnBarrier(),
885 "should be the continuation return barrier");
886 }
887 #endif
888 ContinuationHelper::patch_return_address_at(chunk_bottom_retaddr_slot,
889 chunk->pc());
890
891 // We're always writing to a young chunk, so the GC can't see it until the next safepoint.
892 chunk->set_sp(chunk_new_sp);
893
894 // set chunk->pc to the return address of the topmost frame in the chunk
895 if (_preempt) {
896 // On aarch64, the return pc of the top frame won't necessarily be at sp[-1].
897 // Also, on x64, if the top frame is the native wrapper frame, sp[-1] will not
898 // be the pc we used when creating the oopmap. Get the top's frame last pc from
899 // the anchor instead.
900 address last_pc = _last_frame.pc();
901 ContinuationHelper::patch_return_address_at(chunk_top - frame::sender_sp_ret_address_offset(), last_pc);
902 chunk->set_pc(last_pc);
903 } else {
904 chunk->set_pc(ContinuationHelper::return_address_at(
905 _cont_stack_top - frame::sender_sp_ret_address_offset()));
906 }
907
908 // Fix monitors after unwinding frames to make sure oops are valid.
909 if (_monitors_to_fix > 0) {
910 fix_monitors_in_fast_path();
911 }
912
913 _cont.write();
914
915 log_develop_trace(continuations)("FREEZE CHUNK #" INTPTR_FORMAT " (young)", _cont.hash());
916 LogTarget(Trace, continuations) lt;
917 if (lt.develop_is_enabled()) {
918 LogStream ls(lt);
919 chunk->print_on(true, &ls);
920 }
921
922 // Verification
923 assert(_cont.chunk_invariant(), "");
924 chunk->verify();
925
926 #if CONT_JFR
927 EventContinuationFreezeFast e;
928 if (e.should_commit()) {
929 e.set_id(cast_from_oop<u8>(chunk));
930 DEBUG_ONLY(e.set_allocate(chunk_is_allocated);)
931 e.set_size(cont_size() << LogBytesPerWord);
932 e.commit();
933 }
934 #endif
935 }
936
937 NOINLINE freeze_result FreezeBase::freeze_slow() {
938 #ifdef ASSERT
939 ResourceMark rm;
940 #endif
941
942 log_develop_trace(continuations)("freeze_slow #" INTPTR_FORMAT, _cont.hash());
943 assert(_thread->thread_state() == _thread_in_vm || _thread->thread_state() == _thread_blocked, "");
944
945 #if CONT_JFR
946 EventContinuationFreezeSlow e;
947 if (e.should_commit()) {
948 e.set_id(cast_from_oop<u8>(_cont.continuation()));
949 e.commit();
950 }
951 #endif
952
953 init_rest();
954
955 HandleMark hm(Thread::current());
956
957 frame f = freeze_start_frame();
958
959 LogTarget(Debug, continuations) lt;
960 if (lt.develop_is_enabled()) {
961 LogStream ls(lt);
962 f.print_on(&ls);
963 }
964
965 frame caller; // the frozen caller in the chunk
966 freeze_result res = recurse_freeze(f, caller, 0, false, true);
967
968 if (res == freeze_ok) {
969 finish_freeze(f, caller);
970 _cont.write();
971 assert(_monitors_to_fix == 0, "missing monitors in stack");
972 assert(_thread->held_monitor_count() == 0, "should be 0 now");
973 }
974
975 return res;
976 }
977
978 frame FreezeBase::freeze_start_frame() {
979 if (LIKELY(!_preempt)) {
980 return freeze_start_frame_yield_stub();
981 } else {
982 return freeze_start_frame_on_preempt();
983 }
984 }
985
986 frame FreezeBase::freeze_start_frame_yield_stub() {
987 frame f = _thread->last_frame();
988 assert(SharedRuntime::cont_doYield_stub()->contains(f.pc()), "must be");
989 f = sender<ContinuationHelper::NonInterpretedUnknownFrame>(f);
990 assert(Continuation::is_frame_in_continuation(_thread->last_continuation(), f), "");
991 return f;
992 }
993
994 frame FreezeBase::freeze_start_frame_on_preempt() {
995 assert(_last_frame.sp() == _thread->last_frame().sp(), "_last_frame should be already initialized");
996 assert(Continuation::is_frame_in_continuation(_thread->last_continuation(), _last_frame), "");
997 return _last_frame;
998 }
999
1000 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
1001 NOINLINE freeze_result FreezeBase::recurse_freeze(frame& f, frame& caller, int callee_argsize, bool callee_interpreted, bool top) {
1002 assert(f.unextended_sp() < _bottom_address, ""); // see recurse_freeze_java_frame
1003 assert(f.is_interpreted_frame() || ((top && _preempt) == ContinuationHelper::Frame::is_stub(f.cb()))
1004 || ((top && _preempt) == f.is_native_frame()), "");
1005
1006 if (stack_overflow()) {
1007 return freeze_exception;
1008 }
1009
1010 if (f.is_compiled_frame()) {
1011 if (UNLIKELY(f.oop_map() == nullptr)) {
1012 // special native frame
1013 return freeze_pinned_native;
1014 }
1015 return recurse_freeze_compiled_frame(f, caller, callee_argsize, callee_interpreted);
1016 } else if (f.is_interpreted_frame()) {
1017 assert(!f.interpreter_frame_method()->is_native() || (top && _preempt), "");
1018 return recurse_freeze_interpreted_frame(f, caller, callee_argsize, callee_interpreted);
1019 } else if (top && _preempt) {
1020 assert(f.is_native_frame() || f.is_runtime_frame(), "");
1021 return f.is_native_frame() ? recurse_freeze_native_frame(f, caller) : recurse_freeze_stub_frame(f, caller);
1022 } else {
1023 return freeze_pinned_native;
1024 }
1025 }
1026
1027 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
1028 // See also StackChunkFrameStream<frame_kind>::frame_size()
1029 template<typename FKind>
1030 inline freeze_result FreezeBase::recurse_freeze_java_frame(const frame& f, frame& caller, int fsize, int argsize) {
1031 assert(FKind::is_instance(f), "");
1032
1033 assert(fsize > 0, "");
1034 assert(argsize >= 0, "");
1035 _freeze_size += fsize;
1036 NOT_PRODUCT(_frames++;)
1037
1038 assert(FKind::frame_bottom(f) <= _bottom_address, "");
1039
1040 // We don't use FKind::frame_bottom(f) == _bottom_address because on x64 there's sometimes an extra word between
1041 // enterSpecial and an interpreted frame
1042 if (FKind::frame_bottom(f) >= _bottom_address - 1) {
1043 return finalize_freeze(f, caller, argsize); // recursion end
1044 } else {
1045 frame senderf = sender<FKind>(f);
1046 assert(FKind::interpreted || senderf.sp() == senderf.unextended_sp(), "");
1047 freeze_result result = recurse_freeze(senderf, caller, argsize, FKind::interpreted, false); // recursive call
1048 return result;
1049 }
1050 }
1051
1052 inline void FreezeBase::before_freeze_java_frame(const frame& f, const frame& caller, int fsize, int argsize, bool is_bottom_frame) {
1053 LogTarget(Trace, continuations) lt;
1054 if (lt.develop_is_enabled()) {
1055 LogStream ls(lt);
1056 ls.print_cr("======== FREEZING FRAME interpreted: %d bottom: %d", f.is_interpreted_frame(), is_bottom_frame);
1057 ls.print_cr("fsize: %d argsize: %d", fsize, argsize);
1058 f.print_value_on(&ls, nullptr);
1059 }
1060 assert(caller.is_interpreted_frame() == Interpreter::contains(caller.pc()), "");
1061 }
1062
1063 inline void FreezeBase::after_freeze_java_frame(const frame& hf, bool is_bottom_frame) {
1064 LogTarget(Trace, continuations) lt;
1065 if (lt.develop_is_enabled()) {
1066 LogStream ls(lt);
1067 DEBUG_ONLY(hf.print_value_on(&ls, nullptr);)
1068 assert(hf.is_heap_frame(), "should be");
1069 DEBUG_ONLY(print_frame_layout(hf, false, &ls);)
1070 if (is_bottom_frame) {
1071 ls.print_cr("bottom h-frame:");
1072 hf.print_on(&ls);
1073 }
1074 }
1075 }
1076
1077 // The parameter argsize_md includes metadata that has to be part of caller/callee overlap.
1078 // See also StackChunkFrameStream<frame_kind>::frame_size()
1079 freeze_result FreezeBase::finalize_freeze(const frame& callee, frame& caller, int argsize_md) {
1080 int argsize = argsize_md - frame::metadata_words_at_top;
1081 assert(callee.is_interpreted_frame()
1082 || ContinuationHelper::Frame::is_stub(callee.cb())
1083 || callee.cb()->as_nmethod()->is_osr_method()
1084 || argsize == _cont.argsize(), "argsize: %d cont.argsize: %d", argsize, _cont.argsize());
1085 log_develop_trace(continuations)("bottom: " INTPTR_FORMAT " count %d size: %d argsize: %d",
1086 p2i(_bottom_address), _frames, _freeze_size << LogBytesPerWord, argsize);
1087
1088 LogTarget(Trace, continuations) lt;
1089
1090 #ifdef ASSERT
1091 bool empty = _cont.is_empty();
1092 log_develop_trace(continuations)("empty: %d", empty);
1093 #endif
1094
1095 stackChunkOop chunk = _cont.tail();
1096
1097 assert(chunk == nullptr || (chunk->max_thawing_size() == 0) == chunk->is_empty(), "");
1098
1099 _freeze_size += frame::metadata_words; // for top frame's metadata
1100
1101 int overlap = 0; // the args overlap the caller -- if there is one in this chunk and is of the same kind
1102 int unextended_sp = -1;
1103 if (chunk != nullptr) {
1104 if (!chunk->is_empty()) {
1105 StackChunkFrameStream<ChunkFrames::Mixed> last(chunk);
1106 unextended_sp = chunk->to_offset(StackChunkFrameStream<ChunkFrames::Mixed>(chunk).unextended_sp());
1107 bool top_interpreted = Interpreter::contains(chunk->pc());
1108 if (callee.is_interpreted_frame() == top_interpreted) {
1109 overlap = argsize_md;
1110 }
1111 } else {
1112 unextended_sp = chunk->stack_size() - frame::metadata_words_at_top;
1113 }
1114 }
1115
1116 log_develop_trace(continuations)("finalize _size: %d overlap: %d unextended_sp: %d", _freeze_size, overlap, unextended_sp);
1117
1118 _freeze_size -= overlap;
1119 assert(_freeze_size >= 0, "");
1120
1121 assert(chunk == nullptr || chunk->is_empty()
1122 || unextended_sp == chunk->to_offset(StackChunkFrameStream<ChunkFrames::Mixed>(chunk).unextended_sp()), "");
1123 assert(chunk != nullptr || unextended_sp < _freeze_size, "");
1124
1125 _freeze_size += _monitors_in_lockstack;
1126
1127 // _barriers can be set to true by an allocation in freeze_fast, in which case the chunk is available
1128 bool allocated_old_in_freeze_fast = _barriers;
1129 assert(!allocated_old_in_freeze_fast || (unextended_sp >= _freeze_size && chunk->is_empty()),
1130 "Chunk allocated in freeze_fast is of insufficient size "
1131 "unextended_sp: %d size: %d is_empty: %d", unextended_sp, _freeze_size, chunk->is_empty());
1132 assert(!allocated_old_in_freeze_fast || (!UseZGC && !UseG1GC), "Unexpected allocation");
1133
1134 DEBUG_ONLY(bool empty_chunk = true);
1135 if (unextended_sp < _freeze_size || chunk->is_gc_mode() || (!allocated_old_in_freeze_fast && chunk->requires_barriers())) {
1136 // ALLOCATE NEW CHUNK
1137
1138 if (lt.develop_is_enabled()) {
1139 LogStream ls(lt);
1140 if (chunk == nullptr) {
1141 ls.print_cr("no chunk");
1142 } else {
1143 ls.print_cr("chunk barriers: %d _size: %d free size: %d",
1144 chunk->requires_barriers(), _freeze_size, chunk->sp() - frame::metadata_words);
1145 chunk->print_on(&ls);
1146 }
1147 }
1148
1149 _freeze_size += overlap; // we're allocating a new chunk, so no overlap
1150 // overlap = 0;
1151
1152 chunk = allocate_chunk_slow(_freeze_size, argsize_md);
1153 if (chunk == nullptr) {
1154 return freeze_exception;
1155 }
1156
1157 // Install new chunk
1158 _cont.set_tail(chunk);
1159 assert(chunk->is_empty(), "");
1160 } else {
1161 // REUSE EXISTING CHUNK
1162 log_develop_trace(continuations)("Reusing chunk mixed: %d empty: %d", chunk->has_mixed_frames(), chunk->is_empty());
1163 if (chunk->is_empty()) {
1164 int sp = chunk->stack_size() - argsize_md;
1165 chunk->set_sp(sp);
1166 chunk->set_bottom(sp);
1167 _freeze_size += overlap;
1168 assert(chunk->max_thawing_size() == 0, "");
1169 } DEBUG_ONLY(else empty_chunk = false;)
1170 }
1171 assert(!chunk->is_gc_mode(), "");
1172 assert(!chunk->has_bitmap(), "");
1173 chunk->set_has_mixed_frames(true);
1174
1175 assert(chunk->requires_barriers() == _barriers, "");
1176 assert(!_barriers || chunk->is_empty(), "");
1177
1178 assert(!chunk->is_empty() || StackChunkFrameStream<ChunkFrames::Mixed>(chunk).is_done(), "");
1179 assert(!chunk->is_empty() || StackChunkFrameStream<ChunkFrames::Mixed>(chunk).to_frame().is_empty(), "");
1180
1181 if (_preempt) {
1182 frame f = _thread->last_frame();
1183 if (f.is_interpreted_frame()) {
1184 // Do it now that we know freezing will be successful.
1185 prepare_freeze_interpreted_top_frame(f);
1186 }
1187 }
1188
1189 // We unwind frames after the last safepoint so that the GC will have found the oops in the frames, but before
1190 // writing into the chunk. This is so that an asynchronous stack walk (not at a safepoint) that suspends us here
1191 // will either see no continuation or a consistent chunk.
1192 unwind_frames();
1193
1194 chunk->set_max_thawing_size(chunk->max_thawing_size() + _freeze_size - _monitors_in_lockstack - frame::metadata_words);
1195
1196 if (lt.develop_is_enabled()) {
1197 LogStream ls(lt);
1198 ls.print_cr("top chunk:");
1199 chunk->print_on(&ls);
1200 }
1201
1202 // Fix monitors after unwinding frames to make sure oops are valid. Also do it now to avoid unnecessary
1203 // calls to fix_monitors_in_interpreted_frame/fix_monitors_in_compiled_frame() later.
1204 if (_monitors_to_fix > 0) {
1205 if (_monitors_in_lockstack > 0) {
1206 assert(chunk->sp_address() - chunk->start_address() >= _monitors_in_lockstack, "no room for lockstack");
1207 _thread->lock_stack().move_to_address((oop*)chunk->start_address());
1208
1209 chunk->set_lockstack_size((uint8_t)_monitors_in_lockstack);
1210 chunk->set_has_lockstack(true);
1211
1212 _monitors_to_fix -= _monitors_in_lockstack;
1213 assert(_monitors_to_fix == 0, "invariant");
1214 }
1215 _monitorenter_obj = _thread->is_on_monitorenter() ? _thread->current_pending_monitor()->object() : nullptr;
1216 }
1217
1218 // The topmost existing frame in the chunk; or an empty frame if the chunk is empty
1219 caller = StackChunkFrameStream<ChunkFrames::Mixed>(chunk).to_frame();
1220
1221 DEBUG_ONLY(_last_write = caller.unextended_sp() + (empty_chunk ? argsize_md : overlap);)
1222
1223 assert(chunk->is_in_chunk(_last_write - _freeze_size),
1224 "last_write-size: " INTPTR_FORMAT " start: " INTPTR_FORMAT, p2i(_last_write-_freeze_size), p2i(chunk->start_address()));
1225 #ifdef ASSERT
1226 if (lt.develop_is_enabled()) {
1227 LogStream ls(lt);
1228 ls.print_cr("top hframe before (freeze):");
1229 assert(caller.is_heap_frame(), "should be");
1230 caller.print_on(&ls);
1231 }
1232
1233 assert(!empty || Continuation::is_continuation_entry_frame(callee, nullptr), "");
1234
1235 frame entry = sender(callee);
1236
1237 assert((!empty && Continuation::is_return_barrier_entry(entry.pc())) || (empty && Continuation::is_continuation_enterSpecial(entry)), "");
1238 assert(callee.is_interpreted_frame() || entry.sp() == entry.unextended_sp(), "");
1239 #endif
1240
1241 return freeze_ok_bottom;
1242 }
1243
1244 void FreezeBase::patch(const frame& f, frame& hf, const frame& caller, bool is_bottom_frame) {
1245 if (is_bottom_frame) {
1246 // If we're the bottom frame, we need to replace the return barrier with the real
1247 // caller's pc.
1248 address last_pc = caller.pc();
1249 assert((last_pc == nullptr) == _cont.tail()->is_empty(), "");
1250 ContinuationHelper::Frame::patch_pc(caller, last_pc);
1251 } else {
1252 assert(!caller.is_empty(), "");
1253 }
1254
1255 patch_pd(hf, caller);
1256
1257 if (f.is_interpreted_frame()) {
1258 assert(hf.is_heap_frame(), "should be");
1259 ContinuationHelper::InterpretedFrame::patch_sender_sp(hf, caller);
1260 }
1261
1262 #ifdef ASSERT
1263 if (hf.is_compiled_frame()) {
1264 if (f.is_deoptimized_frame()) { // TODO DEOPT: long term solution: unroll on freeze and patch pc
1265 log_develop_trace(continuations)("Freezing deoptimized frame");
1266 assert(f.cb()->as_nmethod()->is_deopt_pc(f.raw_pc()), "");
1267 assert(f.cb()->as_nmethod()->is_deopt_pc(ContinuationHelper::Frame::real_pc(f)), "");
1268 }
1269 }
1270 #endif
1271 }
1272
1273 #ifdef ASSERT
1274 static void verify_frame_top(const frame& f, intptr_t* top) {
1275 ResourceMark rm;
1276 InterpreterOopMap mask;
1277 f.interpreted_frame_oop_map(&mask);
1278 assert(top <= ContinuationHelper::InterpretedFrame::frame_top(f, &mask),
1279 "frame_top: " INTPTR_FORMAT " Interpreted::frame_top: " INTPTR_FORMAT,
1280 p2i(top), p2i(ContinuationHelper::InterpretedFrame::frame_top(f, &mask)));
1281 }
1282 #endif // ASSERT
1283
1284 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
1285 // See also StackChunkFrameStream<frame_kind>::frame_size()
1286 NOINLINE freeze_result FreezeBase::recurse_freeze_interpreted_frame(frame& f, frame& caller,
1287 int callee_argsize /* incl. metadata */,
1288 bool callee_interpreted) {
1289 adjust_interpreted_frame_unextended_sp(f);
1290
1291 // The frame's top never includes the stack arguments to the callee
1292 intptr_t* const stack_frame_top = ContinuationHelper::InterpretedFrame::frame_top(f, callee_argsize, callee_interpreted);
1293 intptr_t* const stack_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(f);
1294 const int fsize = pointer_delta_as_int(stack_frame_bottom, stack_frame_top);
1295
1296 DEBUG_ONLY(verify_frame_top(f, stack_frame_top));
1297
1298 Method* frame_method = ContinuationHelper::Frame::frame_method(f);
1299 // including metadata between f and its args
1300 const int argsize = ContinuationHelper::InterpretedFrame::stack_argsize(f) + frame::metadata_words_at_top;
1301
1302 log_develop_trace(continuations)("recurse_freeze_interpreted_frame %s _size: %d fsize: %d argsize: %d",
1303 frame_method->name_and_sig_as_C_string(), _freeze_size, fsize, argsize);
1304 // we'd rather not yield inside methods annotated with @JvmtiMountTransition. In the preempt case
1305 // we already checked it is safe to do so in Continuation::is_safe_vthread_to_preempt().
1306 assert(!ContinuationHelper::Frame::frame_method(f)->jvmti_mount_transition() || _preempt, "");
1307
1308 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::InterpretedFrame>(f, caller, fsize, argsize);
1309 if (UNLIKELY(result > freeze_ok_bottom)) {
1310 return result;
1311 }
1312
1313 bool is_bottom_frame = result == freeze_ok_bottom;
1314 assert(!caller.is_empty() || is_bottom_frame, "");
1315
1316 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, 0, is_bottom_frame);)
1317
1318 frame hf = new_heap_frame<ContinuationHelper::InterpretedFrame>(f, caller);
1319 _total_align_size += frame::align_wiggle; // add alignment room for internal interpreted frame alignment on AArch64/PPC64
1320
1321 intptr_t* heap_frame_top = ContinuationHelper::InterpretedFrame::frame_top(hf, callee_argsize, callee_interpreted);
1322 intptr_t* heap_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(hf);
1323 assert(heap_frame_bottom == heap_frame_top + fsize, "");
1324
1325 // Some architectures (like AArch64/PPC64/RISC-V) add padding between the locals and the fixed_frame to keep the fp 16-byte-aligned.
1326 // On those architectures we freeze the padding in order to keep the same fp-relative offsets in the fixed_frame.
1327 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1328 assert(!is_bottom_frame || !caller.is_interpreted_frame() || (heap_frame_top + fsize) == (caller.unextended_sp() + argsize), "");
1329
1330 relativize_interpreted_frame_metadata(f, hf);
1331
1332 patch(f, hf, caller, is_bottom_frame);
1333
1334 CONT_JFR_ONLY(_jfr_info.record_interpreted_frame();)
1335 DEBUG_ONLY(after_freeze_java_frame(hf, is_bottom_frame);)
1336 caller = hf;
1337
1338 // Mark frame_method's GC epoch for class redefinition on_stack calculation.
1339 frame_method->record_gc_epoch();
1340
1341 if (_monitors_to_fix > 0) {
1342 // Check if we have monitors in this frame
1343 fix_monitors_in_interpreted_frame(f);
1344 }
1345
1346 return freeze_ok;
1347 }
1348
1349 // The parameter callee_argsize includes metadata that has to be part of caller/callee overlap.
1350 // See also StackChunkFrameStream<frame_kind>::frame_size()
1351 freeze_result FreezeBase::recurse_freeze_compiled_frame(frame& f, frame& caller,
1352 int callee_argsize /* incl. metadata */,
1353 bool callee_interpreted) {
1354 // The frame's top never includes the stack arguments to the callee
1355 intptr_t* const stack_frame_top = ContinuationHelper::CompiledFrame::frame_top(f, callee_argsize, callee_interpreted);
1356 intptr_t* const stack_frame_bottom = ContinuationHelper::CompiledFrame::frame_bottom(f);
1357 // including metadata between f and its stackargs
1358 const int argsize = ContinuationHelper::CompiledFrame::stack_argsize(f) + frame::metadata_words_at_top;
1359 const int fsize = pointer_delta_as_int(stack_frame_bottom + argsize, stack_frame_top);
1360
1361 log_develop_trace(continuations)("recurse_freeze_compiled_frame %s _size: %d fsize: %d argsize: %d",
1362 ContinuationHelper::Frame::frame_method(f) != nullptr ?
1363 ContinuationHelper::Frame::frame_method(f)->name_and_sig_as_C_string() : "",
1364 _freeze_size, fsize, argsize);
1365 // we'd rather not yield inside methods annotated with @JvmtiMountTransition. In the preempt case
1366 // we already checked it is safe to do so in Continuation::is_safe_vthread_to_preempt().
1367 assert(!ContinuationHelper::Frame::frame_method(f)->jvmti_mount_transition() || _preempt, "");
1368
1369 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::CompiledFrame>(f, caller, fsize, argsize);
1370 if (UNLIKELY(result > freeze_ok_bottom)) {
1371 return result;
1372 }
1373
1374 bool is_bottom_frame = result == freeze_ok_bottom;
1375 assert(!caller.is_empty() || is_bottom_frame, "");
1376
1377 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, argsize, is_bottom_frame);)
1378
1379 frame hf = new_heap_frame<ContinuationHelper::CompiledFrame>(f, caller);
1380
1381 intptr_t* heap_frame_top = ContinuationHelper::CompiledFrame::frame_top(hf, callee_argsize, callee_interpreted);
1382
1383 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1384 assert(!is_bottom_frame || !caller.is_compiled_frame() || (heap_frame_top + fsize) == (caller.unextended_sp() + argsize), "");
1385
1386 if (caller.is_interpreted_frame()) {
1387 _total_align_size += frame::align_wiggle; // See Thaw::align
1388 }
1389
1390 patch(f, hf, caller, is_bottom_frame);
1391
1392 assert(is_bottom_frame || Interpreter::contains(ContinuationHelper::CompiledFrame::real_pc(caller)) == caller.is_interpreted_frame(), "");
1393
1394 DEBUG_ONLY(after_freeze_java_frame(hf, is_bottom_frame);)
1395 caller = hf;
1396
1397 if (_monitors_to_fix > 0) {
1398 // Check if we have monitors in this frame
1399 fix_monitors_in_compiled_frame(f, SmallRegisterMap::instance);
1400 }
1401
1402 return freeze_ok;
1403 }
1404
1405 NOINLINE freeze_result FreezeBase::recurse_freeze_stub_frame(frame& f, frame& caller) {
1406 DEBUG_ONLY(frame fsender = sender(f);)
1407 assert(fsender.is_compiled_frame(), "sender should be compiled frame");
1408 assert(_thread->is_on_monitorenter(), "");
1409
1410 intptr_t* const stack_frame_top = ContinuationHelper::StubFrame::frame_top(f);
1411 const int fsize = f.cb()->frame_size();
1412
1413 log_develop_trace(continuations)("recurse_freeze_stub_frame %s _size: %d fsize: %d :: " INTPTR_FORMAT " - " INTPTR_FORMAT,
1414 f.cb()->name(), _freeze_size, fsize, p2i(stack_frame_top), p2i(stack_frame_top+fsize));
1415
1416 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::StubFrame>(f, caller, fsize, 0);
1417 if (UNLIKELY(result > freeze_ok_bottom)) {
1418 return result;
1419 }
1420
1421 bool is_bottom_frame = result == freeze_ok_bottom;
1422 assert(!caller.is_empty() || (is_bottom_frame && !_cont.is_empty()), "");
1423
1424 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, 0, is_bottom_frame);)
1425
1426 frame hf = new_heap_frame<ContinuationHelper::StubFrame>(f, caller);
1427 intptr_t* heap_frame_top = ContinuationHelper::StubFrame::frame_top(hf);
1428
1429 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1430
1431 if (caller.is_interpreted_frame()) {
1432 _total_align_size += frame::align_wiggle;
1433 }
1434
1435 patch(f, hf, caller, is_bottom_frame);
1436
1437 DEBUG_ONLY(after_freeze_java_frame(hf, is_bottom_frame);)
1438
1439 caller = hf;
1440 return freeze_ok;
1441 }
1442
1443 NOINLINE freeze_result FreezeBase::recurse_freeze_native_frame(frame& f, frame& caller) {
1444 if (!f.cb()->as_nmethod()->method()->is_object_wait0()) {
1445 assert(_thread->is_on_monitorenter(), "");
1446 // Synchronized native method case. Unlike the interpreter native wrapper, the compiled
1447 // native wrapper tries to acquire the monitor after marshalling the arguments from the
1448 // caller into the native convention. This is so that we have a valid oopMap in case of
1449 // having to block in the slow path. But that would require freezing those registers too
1450 // and then fixing them back on thaw in case of oops. To avoid complicating things and
1451 // given that this would be a rare case anyways just pin the vthread to the carrier.
1452 return freeze_pinned_native;
1453 }
1454
1455 intptr_t* const stack_frame_top = ContinuationHelper::NativeFrame::frame_top(f);
1456 const int fsize = f.cb()->frame_size();
1457
1458 log_develop_trace(continuations)("recurse_freeze_native_frame %s _size: %d fsize: %d :: " INTPTR_FORMAT " - " INTPTR_FORMAT,
1459 f.cb()->name(), _freeze_size, fsize, p2i(stack_frame_top), p2i(stack_frame_top+fsize));
1460
1461 freeze_result result = recurse_freeze_java_frame<ContinuationHelper::NativeFrame>(f, caller, fsize, 0);
1462 if (UNLIKELY(result > freeze_ok_bottom)) {
1463 return result;
1464 }
1465
1466 assert(result == freeze_ok, "should have caller frame");
1467 DEBUG_ONLY(before_freeze_java_frame(f, caller, fsize, 0 /* argsize */, false /* is_bottom_frame */);)
1468
1469 frame hf = new_heap_frame<ContinuationHelper::NativeFrame>(f, caller);
1470 intptr_t* heap_frame_top = ContinuationHelper::NativeFrame::frame_top(hf);
1471
1472 copy_to_chunk(stack_frame_top, heap_frame_top, fsize);
1473
1474 if (caller.is_interpreted_frame()) {
1475 _total_align_size += frame::align_wiggle;
1476 }
1477
1478 patch(f, hf, caller, false /* is_bottom_frame */);
1479
1480 DEBUG_ONLY(after_freeze_java_frame(hf, false /* is_bottom_frame */);)
1481
1482 caller = hf;
1483 return freeze_ok;
1484 }
1485
1486 NOINLINE void FreezeBase::finish_freeze(const frame& f, const frame& top) {
1487 stackChunkOop chunk = _cont.tail();
1488
1489 LogTarget(Trace, continuations) lt;
1490 if (lt.develop_is_enabled()) {
1491 LogStream ls(lt);
1492 assert(top.is_heap_frame(), "should be");
1493 top.print_on(&ls);
1494 }
1495
1496 set_top_frame_metadata_pd(top);
1497
1498 chunk->set_sp(chunk->to_offset(top.sp()));
1499 chunk->set_pc(top.pc());
1500
1501 chunk->set_max_thawing_size(chunk->max_thawing_size() + _total_align_size);
1502
1503 assert(chunk->sp_address() - chunk->start_address() >= _monitors_in_lockstack, "clash with lockstack");
1504
1505 // At this point the chunk is consistent
1506
1507 if (UNLIKELY(_barriers)) {
1508 log_develop_trace(continuations)("do barriers on old chunk");
1509 // Serial and Parallel GC can allocate objects directly into the old generation.
1510 // Then we want to relativize the derived pointers eagerly so that
1511 // old chunks are all in GC mode.
1512 assert(!UseG1GC, "G1 can not deal with allocating outside of eden");
1513 assert(!UseZGC, "ZGC can not deal with allocating chunks visible to marking");
1514 if (UseShenandoahGC) {
1515 _cont.tail()->relativize_derived_pointers_concurrently();
1516 } else {
1517 ContinuationGCSupport::transform_stack_chunk(_cont.tail());
1518 }
1519 // For objects in the old generation we must maintain the remembered set
1520 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>();
1521 }
1522
1523 log_develop_trace(continuations)("finish_freeze: has_mixed_frames: %d", chunk->has_mixed_frames());
1524 if (lt.develop_is_enabled()) {
1525 LogStream ls(lt);
1526 chunk->print_on(true, &ls);
1527 }
1528
1529 if (lt.develop_is_enabled()) {
1530 LogStream ls(lt);
1531 ls.print_cr("top hframe after (freeze):");
1532 assert(_cont.last_frame().is_heap_frame(), "should be");
1533 _cont.last_frame().print_on(&ls);
1534 DEBUG_ONLY(print_frame_layout(top, false, &ls);)
1535 }
1536
1537 assert(_cont.chunk_invariant(), "");
1538 }
1539
1540 inline bool FreezeBase::stack_overflow() { // detect stack overflow in recursive native code
1541 JavaThread* t = !_preempt ? _thread : JavaThread::current();
1542 assert(t == JavaThread::current(), "");
1543 if (os::current_stack_pointer() < t->stack_overflow_state()->shadow_zone_safe_limit()) {
1544 if (!_preempt) {
1545 ContinuationWrapper::SafepointOp so(t, _cont); // could also call _cont.done() instead
1546 Exceptions::_throw_msg(t, __FILE__, __LINE__, vmSymbols::java_lang_StackOverflowError(), "Stack overflow while freezing");
1547 }
1548 return true;
1549 }
1550 return false;
1551 }
1552
1553 class StackChunkAllocator : public MemAllocator {
1554 const size_t _stack_size;
1555 int _argsize_md;
1556 ContinuationWrapper& _continuation_wrapper;
1557 JvmtiSampledObjectAllocEventCollector* const _jvmti_event_collector;
1558 JavaThread* const _target;
1559 mutable bool _took_slow_path;
1560
1561 // Does the minimal amount of initialization needed for a TLAB allocation.
1562 // We don't need to do a full initialization, as such an allocation need not be immediately walkable.
1563 virtual oop initialize(HeapWord* mem) const override {
1564 assert(_stack_size > 0, "");
1565 assert(_stack_size <= max_jint, "");
1566 assert(_word_size > _stack_size, "");
1567
1568 // zero out fields (but not the stack)
1569 const size_t hs = oopDesc::header_size();
1570 oopDesc::set_klass_gap(mem, 0);
1571 Copy::fill_to_aligned_words(mem + hs, vmClasses::StackChunk_klass()->size_helper() - hs);
1572
1573 int bottom = (int)_stack_size - _argsize_md;
1574
1575 jdk_internal_vm_StackChunk::set_size(mem, (int)_stack_size);
1576 jdk_internal_vm_StackChunk::set_bottom(mem, bottom);
1577 jdk_internal_vm_StackChunk::set_sp(mem, bottom);
1578
1579 return finish(mem);
1580 }
1581
1582 stackChunkOop allocate_fast() const {
1583 if (!UseTLAB) {
1584 return nullptr;
1585 }
1586
1587 HeapWord* const mem = MemAllocator::mem_allocate_inside_tlab_fast();
1588 if (mem == nullptr) {
1589 return nullptr;
1590 }
1591
1592 oop obj = initialize(mem);
1593 return stackChunkOopDesc::cast(obj);
1594 }
1595
1596 bool is_preempt() const { return _thread != _target; }
1597
1598 public:
1599 StackChunkAllocator(Klass* klass,
1600 size_t word_size,
1601 Thread* thread,
1602 size_t stack_size,
1603 int argsize_md,
1604 ContinuationWrapper& continuation_wrapper,
1605 JvmtiSampledObjectAllocEventCollector* jvmti_event_collector,
1606 JavaThread* target)
1607 : MemAllocator(klass, word_size, thread),
1608 _stack_size(stack_size),
1609 _argsize_md(argsize_md),
1610 _continuation_wrapper(continuation_wrapper),
1611 _jvmti_event_collector(jvmti_event_collector),
1612 _target(target),
1613 _took_slow_path(false) {}
1614
1615 // Provides it's own, specialized allocation which skips instrumentation
1616 // if the memory can be allocated without going to a slow-path.
1617 stackChunkOop allocate() const {
1618 // First try to allocate without any slow-paths or instrumentation.
1619 stackChunkOop obj = allocate_fast();
1620 if (obj != nullptr) {
1621 return obj;
1622 }
1623
1624 // Now try full-blown allocation with all expensive operations,
1625 // including potentially safepoint operations.
1626 _took_slow_path = true;
1627
1628 // Protect unhandled Loom oops
1629 ContinuationWrapper::SafepointOp so(_thread, _continuation_wrapper);
1630
1631 // Can safepoint
1632 _jvmti_event_collector->start();
1633
1634 // Can safepoint
1635 return stackChunkOopDesc::cast(MemAllocator::allocate());
1636 }
1637
1638 bool took_slow_path() const {
1639 return _took_slow_path;
1640 }
1641 };
1642
1643 template <typename ConfigT>
1644 stackChunkOop Freeze<ConfigT>::allocate_chunk(size_t stack_size, int argsize_md) {
1645 log_develop_trace(continuations)("allocate_chunk allocating new chunk");
1646
1647 InstanceStackChunkKlass* klass = InstanceStackChunkKlass::cast(vmClasses::StackChunk_klass());
1648 size_t size_in_words = klass->instance_size(stack_size);
1649
1650 if (CollectedHeap::stack_chunk_max_size() > 0 && size_in_words >= CollectedHeap::stack_chunk_max_size()) {
1651 if (!_preempt) {
1652 throw_stack_overflow_on_humongous_chunk();
1653 }
1654 return nullptr;
1655 }
1656
1657 JavaThread* current = _preempt ? JavaThread::current() : _thread;
1658 assert(current == JavaThread::current(), "should be current");
1659
1660 // Allocate the chunk.
1661 //
1662 // This might safepoint while allocating, but all safepointing due to
1663 // instrumentation have been deferred. This property is important for
1664 // some GCs, as this ensures that the allocated object is in the young
1665 // generation / newly allocated memory.
1666 StackChunkAllocator allocator(klass, size_in_words, current, stack_size, argsize_md, _cont, _jvmti_event_collector, _thread);
1667 stackChunkOop chunk = allocator.allocate();
1668
1669 if (chunk == nullptr) {
1670 return nullptr; // OOME
1671 }
1672
1673 // assert that chunk is properly initialized
1674 assert(chunk->stack_size() == (int)stack_size, "");
1675 assert(chunk->size() >= stack_size, "chunk->size(): %zu size: %zu", chunk->size(), stack_size);
1676 assert(chunk->sp() == chunk->bottom(), "");
1677 assert((intptr_t)chunk->start_address() % 8 == 0, "");
1678 assert(chunk->max_thawing_size() == 0, "");
1679 assert(chunk->pc() == nullptr, "");
1680 assert(chunk->is_empty(), "");
1681 assert(chunk->flags() == 0, "");
1682 assert(chunk->is_gc_mode() == false, "");
1683 assert(chunk->lockstack_size() == 0, "");
1684 assert(chunk->object_waiter() == nullptr, "");
1685
1686 // fields are uninitialized
1687 chunk->set_parent_access<IS_DEST_UNINITIALIZED>(_cont.last_nonempty_chunk());
1688 chunk->set_cont_access<IS_DEST_UNINITIALIZED>(_cont.continuation());
1689
1690 #if INCLUDE_ZGC
1691 if (UseZGC) {
1692 if (ZGenerational) {
1693 ZStackChunkGCData::initialize(chunk);
1694 }
1695 assert(!chunk->requires_barriers(), "ZGC always allocates in the young generation");
1696 _barriers = false;
1697 } else
1698 #endif
1699 #if INCLUDE_SHENANDOAHGC
1700 if (UseShenandoahGC) {
1701 _barriers = chunk->requires_barriers();
1702 } else
1703 #endif
1704 {
1705 if (!allocator.took_slow_path()) {
1706 // Guaranteed to be in young gen / newly allocated memory
1707 assert(!chunk->requires_barriers(), "Unfamiliar GC requires barriers on TLAB allocation");
1708 _barriers = false;
1709 } else {
1710 // Some GCs could put direct allocations in old gen for slow-path
1711 // allocations; need to explicitly check if that was the case.
1712 _barriers = chunk->requires_barriers();
1713 }
1714 }
1715
1716 if (_barriers) {
1717 log_develop_trace(continuations)("allocation requires barriers");
1718 }
1719
1720 assert(chunk->parent() == nullptr || chunk->parent()->is_stackChunk(), "");
1721
1722 return chunk;
1723 }
1724
1725 void FreezeBase::throw_stack_overflow_on_humongous_chunk() {
1726 ContinuationWrapper::SafepointOp so(_thread, _cont); // could also call _cont.done() instead
1727 Exceptions::_throw_msg(_thread, __FILE__, __LINE__, vmSymbols::java_lang_StackOverflowError(), "Humongous stack chunk");
1728 }
1729
1730 #if INCLUDE_JVMTI
1731 static int num_java_frames(ContinuationWrapper& cont) {
1732 ResourceMark rm; // used for scope traversal in num_java_frames(nmethod*, address)
1733 int count = 0;
1734 for (stackChunkOop chunk = cont.tail(); chunk != nullptr; chunk = chunk->parent()) {
1735 count += chunk->num_java_frames();
1736 }
1737 return count;
1738 }
1739
1740 static void invalidate_jvmti_stack(JavaThread* thread) {
1741 if (thread->is_interp_only_mode()) {
1742 JvmtiThreadState *state = thread->jvmti_thread_state();
1743 if (state != nullptr)
1744 state->invalidate_cur_stack_depth();
1745 }
1746 }
1747
1748 static void jvmti_yield_cleanup(JavaThread* thread, ContinuationWrapper& cont) {
1749 if (JvmtiExport::can_post_frame_pop()) {
1750 int num_frames = num_java_frames(cont);
1751
1752 ContinuationWrapper::SafepointOp so(Thread::current(), cont);
1753 JvmtiExport::continuation_yield_cleanup(JavaThread::current(), num_frames);
1754 }
1755 invalidate_jvmti_stack(thread);
1756 }
1757
1758 static void jvmti_mount_end(JavaThread* current, ContinuationWrapper& cont, frame top) {
1759 assert(current->vthread() != nullptr, "must be");
1760
1761 HandleMarkCleaner hm(current);
1762 Handle vth(current, current->vthread());
1763
1764 ContinuationWrapper::SafepointOp so(current, cont);
1765
1766 // Since we might safepoint set the anchor so that the stack can we walked.
1767 set_anchor(current, top.sp());
1768
1769 JRT_BLOCK
1770 current->rebind_to_jvmti_thread_state_of(vth());
1771 {
1772 MutexLocker mu(JvmtiThreadState_lock);
1773 JvmtiThreadState* state = current->jvmti_thread_state();
1774 if (state != NULL && state->is_pending_interp_only_mode()) {
1775 JvmtiEventController::enter_interp_only_mode(state);
1776 }
1777 }
1778 assert(current->is_in_VTMS_transition(), "sanity check");
1779 assert(!current->is_in_tmp_VTMS_transition(), "sanity check");
1780 JvmtiVTMSTransitionDisabler::finish_VTMS_transition((jthread)vth.raw_value(), /* is_mount */ true);
1781
1782 // If pending_jvmti_unmount_event() is true here we are in the preemption
1783 // cancelled case. Since we never unmounted we don't post the mount event
1784 // and just clear the pending unmount flag.
1785 if (current->pending_jvmti_unmount_event()) {
1786 current->set_pending_jvmti_unmount_event(false);
1787 } else if (JvmtiExport::should_post_vthread_mount()) {
1788 JvmtiExport::post_vthread_mount((jthread)vth.raw_value());
1789 }
1790
1791 if (current->pending_contended_entered_event()) {
1792 JvmtiExport::post_monitor_contended_entered(current, current->contended_entered_monitor());
1793 current->set_contended_entered_monitor(nullptr);
1794 }
1795 JRT_BLOCK_END
1796
1797 clear_anchor(current);
1798 }
1799 #endif // INCLUDE_JVMTI
1800
1801 #ifdef ASSERT
1802
1803 // There are no interpreted frames if we're not called from the interpreter and we haven't ancountered an i2c
1804 // adapter or called Deoptimization::unpack_frames. As for native frames, upcalls from JNI also go through the
1805 // interpreter (see JavaCalls::call_helper), while the UpcallLinker explicitly sets cont_fastpath.
1806 bool FreezeBase::check_valid_fast_path() {
1807 ContinuationEntry* ce = _thread->last_continuation();
1808 RegisterMap map(_thread,
1809 RegisterMap::UpdateMap::skip,
1810 RegisterMap::ProcessFrames::skip,
1811 RegisterMap::WalkContinuation::skip);
1812 map.set_include_argument_oops(false);
1813 int i = 0;
1814 for (frame f = freeze_start_frame(); Continuation::is_frame_in_continuation(ce, f); f = f.sender(&map), i++) {
1815 if (!((f.is_compiled_frame() && !f.is_deoptimized_frame()) || (i == 0 && (f.is_runtime_frame() || f.is_native_frame())))) {
1816 return false;
1817 }
1818 }
1819 return true;
1820 }
1821 #endif // ASSERT
1822
1823 static inline int freeze_epilog(ContinuationWrapper& cont) {
1824 verify_continuation(cont.continuation());
1825 assert(!cont.is_empty(), "");
1826
1827 log_develop_debug(continuations)("=== End of freeze cont ### #" INTPTR_FORMAT, cont.hash());
1828 return 0;
1829 }
1830
1831 static int freeze_epilog(JavaThread* thread, ContinuationWrapper& cont, freeze_result res) {
1832 if (UNLIKELY(res != freeze_ok)) {
1833 verify_continuation(cont.continuation());
1834 log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1835 return res;
1836 }
1837
1838 JVMTI_ONLY(jvmti_yield_cleanup(thread, cont)); // can safepoint
1839 return freeze_epilog(cont);
1840 }
1841
1842 static int preempt_epilog(ContinuationWrapper& cont, freeze_result res, frame& old_last_frame, int freeze_kind) {
1843 if (UNLIKELY(res != freeze_ok)) {
1844 verify_continuation(cont.continuation());
1845 log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1846 return res;
1847 }
1848
1849 patch_return_pc_with_preempt_stub(old_last_frame);
1850 cont.set_preempted(true);
1851 cont.tail()->set_preempt_kind(freeze_kind);
1852
1853 return freeze_epilog(cont);
1854 }
1855
1856 template<typename ConfigT, bool preempt>
1857 static inline int freeze_internal(JavaThread* current, intptr_t* const sp, int freeze_kind) {
1858 assert(!current->has_pending_exception(), "");
1859
1860 #ifdef ASSERT
1861 log_trace(continuations)("~~~~ freeze sp: " INTPTR_FORMAT "JavaThread: " INTPTR_FORMAT, p2i(current->last_continuation()->entry_sp()), p2i(current));
1862 log_frames(current);
1863 #endif
1864
1865 CONT_JFR_ONLY(EventContinuationFreeze event;)
1866
1867 ContinuationEntry* entry = current->last_continuation();
1868
1869 oop oopCont = entry->cont_oop(current);
1870 assert(oopCont == current->last_continuation()->cont_oop(current), "");
1871 assert(ContinuationEntry::assert_entry_frame_laid_out(current), "");
1872
1873 verify_continuation(oopCont);
1874 ContinuationWrapper cont(current, oopCont);
1875 log_develop_debug(continuations)("FREEZE #" INTPTR_FORMAT " " INTPTR_FORMAT, cont.hash(), p2i((oopDesc*)oopCont));
1876
1877 assert(entry->is_virtual_thread() == (entry->scope(current) == java_lang_VirtualThread::vthread_scope()), "");
1878
1879 const bool pinned_monitor = NOT_LOOM_MONITOR_SUPPORT(current->held_monitor_count() > 0) LOOM_MONITOR_SUPPORT_ONLY(current->jni_monitor_count() > 0);
1880 if (entry->is_pinned() || pinned_monitor) {
1881 log_develop_debug(continuations)("PINNED due to critical section/hold monitor");
1882 verify_continuation(cont.continuation());
1883 freeze_result res = entry->is_pinned() ? freeze_pinned_cs : freeze_pinned_monitor;
1884 log_develop_trace(continuations)("=== end of freeze (fail %d)", res);
1885 // Avoid Thread.yield() loops without safepoint polls.
1886 if (SafepointMechanism::should_process(current) && !preempt) {
1887 cont.done(); // allow safepoint
1888 ThreadInVMfromJava tivmfj(current);
1889 }
1890 return res;
1891 }
1892
1893 Freeze<ConfigT> freeze(current, cont, sp, preempt);
1894
1895 assert(!current->cont_fastpath() || freeze.check_valid_fast_path(), "");
1896 bool fast = UseContinuationFastPath && current->cont_fastpath();
1897 if (fast && freeze.size_if_fast_freeze_available() > 0) {
1898 freeze.freeze_fast_existing_chunk();
1899 CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1900 return !preempt ? freeze_epilog(cont) : preempt_epilog(cont, freeze_ok, freeze.last_frame(), freeze_kind);
1901 }
1902
1903 if (preempt) {
1904 JvmtiSampledObjectAllocEventCollector jsoaec(false);
1905 freeze.set_jvmti_event_collector(&jsoaec);
1906
1907 freeze_result res = fast ? freeze.try_freeze_fast() : freeze.freeze_slow();
1908
1909 CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1910 preempt_epilog(cont, res, freeze.last_frame(), freeze_kind);
1911 return res;
1912 }
1913
1914 log_develop_trace(continuations)("chunk unavailable; transitioning to VM");
1915 assert(current == JavaThread::current(), "must be current thread");
1916 JRT_BLOCK
1917 // delays a possible JvmtiSampledObjectAllocEventCollector in alloc_chunk
1918 JvmtiSampledObjectAllocEventCollector jsoaec(false);
1919 freeze.set_jvmti_event_collector(&jsoaec);
1920
1921 freeze_result res = fast ? freeze.try_freeze_fast() : freeze.freeze_slow();
1922
1923 CONT_JFR_ONLY(freeze.jfr_info().post_jfr_event(&event, oopCont, current);)
1924 freeze_epilog(current, cont, res);
1925 cont.done(); // allow safepoint in the transition back to Java
1926 return res;
1927 JRT_BLOCK_END
1928 }
1929
1930 static freeze_result is_pinned0(JavaThread* thread, oop cont_scope, bool safepoint) {
1931 ContinuationEntry* entry = thread->last_continuation();
1932 if (entry == nullptr) {
1933 return freeze_ok;
1934 }
1935 if (entry->is_pinned()) {
1936 return freeze_pinned_cs;
1937 } else if (thread->held_monitor_count() > 0) {
1938 return freeze_pinned_monitor;
1939 }
1940
1941 RegisterMap map(thread,
1942 RegisterMap::UpdateMap::include,
1943 RegisterMap::ProcessFrames::skip,
1944 RegisterMap::WalkContinuation::skip);
1945 map.set_include_argument_oops(false);
1946 frame f = thread->last_frame();
1947
1948 if (!safepoint) {
1949 f = f.sender(&map); // this is the yield frame
1950 } else { // safepoint yield
1951 #if (defined(X86) || defined(AARCH64) || defined(RISCV64)) && !defined(ZERO)
1952 f.set_fp(f.real_fp()); // Instead of this, maybe in ContinuationWrapper::set_last_frame always use the real_fp?
1953 #else
1954 Unimplemented();
1955 #endif
1956 if (!Interpreter::contains(f.pc())) {
1957 assert(ContinuationHelper::Frame::is_stub(f.cb()), "must be");
1958 assert(f.oop_map() != nullptr, "must be");
1959 f.oop_map()->update_register_map(&f, &map); // we have callee-save registers in this case
1960 }
1961 }
1962
1963 while (true) {
1964 if ((f.is_interpreted_frame() && f.interpreter_frame_method()->is_native()) || f.is_native_frame()) {
1965 return freeze_pinned_native;
1966 }
1967
1968 f = f.sender(&map);
1969 if (!Continuation::is_frame_in_continuation(entry, f)) {
1970 oop scope = jdk_internal_vm_Continuation::scope(entry->cont_oop(thread));
1971 if (scope == cont_scope) {
1972 break;
1973 }
1974 intx monitor_count = entry->parent_held_monitor_count();
1975 entry = entry->parent();
1976 if (entry == nullptr) {
1977 break;
1978 }
1979 if (entry->is_pinned()) {
1980 return freeze_pinned_cs;
1981 } else if (monitor_count > 0) {
1982 return freeze_pinned_monitor;
1983 }
1984 }
1985 }
1986 return freeze_ok;
1987 }
1988
1989 /////////////// THAW ////
1990
1991 static int thaw_size(stackChunkOop chunk) {
1992 int size = chunk->max_thawing_size();
1993 size += frame::metadata_words; // For the top pc+fp in push_return_frame or top = stack_sp - frame::metadata_words in thaw_fast
1994 size += 2*frame::align_wiggle; // in case of alignments at the top and bottom
1995 size += frame::metadata_words; // for preemption case (see push_preempt_rerun_adapter)
1996 return size;
1997 }
1998
1999 // make room on the stack for thaw
2000 // returns the size in bytes, or 0 on failure
2001 static inline int prepare_thaw_internal(JavaThread* thread, bool return_barrier) {
2002 log_develop_trace(continuations)("~~~~ prepare_thaw return_barrier: %d", return_barrier);
2003
2004 assert(thread == JavaThread::current(), "");
2005
2006 ContinuationEntry* ce = thread->last_continuation();
2007 assert(ce != nullptr, "");
2008 oop continuation = ce->cont_oop(thread);
2009 assert(continuation == get_continuation(thread), "");
2010 verify_continuation(continuation);
2011
2012 stackChunkOop chunk = jdk_internal_vm_Continuation::tail(continuation);
2013 assert(chunk != nullptr, "");
2014
2015 // The tail can be empty because it might still be available for another freeze.
2016 // However, here we want to thaw, so we get rid of it (it will be GCed).
2017 if (UNLIKELY(chunk->is_empty())) {
2018 chunk = chunk->parent();
2019 assert(chunk != nullptr, "");
2020 assert(!chunk->is_empty(), "");
2021 jdk_internal_vm_Continuation::set_tail(continuation, chunk);
2022 }
2023
2024 // Verification
2025 chunk->verify();
2026 assert(chunk->max_thawing_size() > 0, "chunk invariant violated; expected to not be empty");
2027
2028 // Only make space for the last chunk because we only thaw from the last chunk
2029 int size = thaw_size(chunk) << LogBytesPerWord;
2030
2031 const address bottom = (address)thread->last_continuation()->entry_sp();
2032 // 300 is an estimate for stack size taken for this native code, in addition to StackShadowPages
2033 // for the Java frames in the check below.
2034 if (!stack_overflow_check(thread, size + 300, bottom)) {
2035 return 0;
2036 }
2037
2038 log_develop_trace(continuations)("prepare_thaw bottom: " INTPTR_FORMAT " top: " INTPTR_FORMAT " size: %d",
2039 p2i(bottom), p2i(bottom - size), size);
2040 return size;
2041 }
2042
2043 class ThawBase : public StackObj {
2044 protected:
2045 JavaThread* _thread;
2046 ContinuationWrapper& _cont;
2047 CONT_JFR_ONLY(FreezeThawJfrInfo _jfr_info;)
2048
2049 intptr_t* _fastpath;
2050 bool _barriers;
2051 intptr_t* _top_unextended_sp_before_thaw;
2052 int _align_size;
2053 DEBUG_ONLY(intptr_t* _top_stack_address);
2054
2055 StackChunkFrameStream<ChunkFrames::Mixed> _stream;
2056
2057 NOT_PRODUCT(int _frames;)
2058
2059 protected:
2060 ThawBase(JavaThread* thread, ContinuationWrapper& cont) :
2061 _thread(thread), _cont(cont),
2062 _fastpath(nullptr) {
2063 DEBUG_ONLY(_top_unextended_sp_before_thaw = nullptr;)
2064 assert (cont.tail() != nullptr, "no last chunk");
2065 DEBUG_ONLY(_top_stack_address = _cont.entrySP() - thaw_size(cont.tail());)
2066 }
2067
2068 void clear_chunk(stackChunkOop chunk);
2069 int remove_top_compiled_frame_from_chunk(stackChunkOop chunk, int &argsize);
2070 void copy_from_chunk(intptr_t* from, intptr_t* to, int size);
2071
2072 // fast path
2073 inline void prefetch_chunk_pd(void* start, int size_words);
2074 void patch_return(intptr_t* sp, bool is_last);
2075
2076 intptr_t* handle_preempted_continuation(intptr_t* sp, int preempt_kind, bool fast_case);
2077 inline intptr_t* push_resume_adapter(frame& top);
2078 inline intptr_t* push_resume_monitor_operation(stackChunkOop chunk);
2079 inline void fix_native_wrapper_return_pc_pd(frame& top);
2080 void throw_interrupted_exception(JavaThread* current, frame& top);
2081
2082 void recurse_thaw(const frame& heap_frame, frame& caller, int num_frames, bool top_on_preempt_case);
2083 void finish_thaw(frame& f);
2084
2085 private:
2086 template<typename FKind> bool recurse_thaw_java_frame(frame& caller, int num_frames);
2087 void finalize_thaw(frame& entry, int argsize);
2088
2089 inline bool seen_by_gc();
2090
2091 inline void before_thaw_java_frame(const frame& hf, const frame& caller, bool bottom, int num_frame);
2092 inline void after_thaw_java_frame(const frame& f, bool bottom);
2093 inline void patch(frame& f, const frame& caller, bool bottom);
2094 void clear_bitmap_bits(address start, address end);
2095
2096 NOINLINE void recurse_thaw_interpreted_frame(const frame& hf, frame& caller, int num_frames);
2097 void recurse_thaw_compiled_frame(const frame& hf, frame& caller, int num_frames, bool stub_caller);
2098 void recurse_thaw_stub_frame(const frame& hf, frame& caller, int num_frames);
2099 void recurse_thaw_native_frame(const frame& hf, frame& caller, int num_frames);
2100
2101 void push_return_frame(frame& f);
2102 inline frame new_entry_frame();
2103 template<typename FKind> frame new_stack_frame(const frame& hf, frame& caller, bool bottom);
2104 inline void patch_pd(frame& f, const frame& sender);
2105 inline void patch_pd(frame& f, intptr_t* caller_sp);
2106 inline intptr_t* align(const frame& hf, intptr_t* frame_sp, frame& caller, bool bottom);
2107
2108 void maybe_set_fastpath(intptr_t* sp) { if (sp > _fastpath) _fastpath = sp; }
2109
2110 static inline void derelativize_interpreted_frame_metadata(const frame& hf, const frame& f);
2111
2112 public:
2113 CONT_JFR_ONLY(FreezeThawJfrInfo& jfr_info() { return _jfr_info; })
2114 };
2115
2116 template <typename ConfigT>
2117 class Thaw : public ThawBase {
2118 public:
2119 Thaw(JavaThread* thread, ContinuationWrapper& cont) : ThawBase(thread, cont) {}
2120
2121 inline bool can_thaw_fast(stackChunkOop chunk) {
2122 return !_barriers
2123 && _thread->cont_fastpath_thread_state()
2124 && !chunk->has_thaw_slowpath_condition()
2125 && !PreserveFramePointer;
2126 }
2127
2128 inline intptr_t* thaw(Continuation::thaw_kind kind);
2129 NOINLINE intptr_t* thaw_fast(stackChunkOop chunk);
2130 NOINLINE intptr_t* thaw_slow(stackChunkOop chunk, Continuation::thaw_kind kind);
2131 inline void patch_caller_links(intptr_t* sp, intptr_t* bottom);
2132 };
2133
2134 template <typename ConfigT>
2135 inline intptr_t* Thaw<ConfigT>::thaw(Continuation::thaw_kind kind) {
2136 verify_continuation(_cont.continuation());
2137 assert(!jdk_internal_vm_Continuation::done(_cont.continuation()), "");
2138 assert(!_cont.is_empty(), "");
2139
2140 stackChunkOop chunk = _cont.tail();
2141 assert(chunk != nullptr, "guaranteed by prepare_thaw");
2142 assert(!chunk->is_empty(), "guaranteed by prepare_thaw");
2143
2144 _barriers = chunk->requires_barriers();
2145 return (LIKELY(can_thaw_fast(chunk))) ? thaw_fast(chunk)
2146 : thaw_slow(chunk, kind);
2147 }
2148
2149 class ReconstructedStack : public StackObj {
2150 intptr_t* _base; // _cont.entrySP(); // top of the entry frame
2151 int _thaw_size;
2152 int _argsize;
2153 public:
2154 ReconstructedStack(intptr_t* base, int thaw_size, int argsize)
2155 : _base(base), _thaw_size(thaw_size - (argsize == 0 ? frame::metadata_words_at_top : 0)), _argsize(argsize) {
2156 // The only possible source of misalignment is stack-passed arguments b/c compiled frames are 16-byte aligned.
2157 assert(argsize != 0 || (_base - _thaw_size) == ContinuationHelper::frame_align_pointer(_base - _thaw_size), "");
2158 // We're at most one alignment word away from entrySP
2159 assert(_base - 1 <= top() + total_size() + frame::metadata_words_at_bottom, "missed entry frame");
2160 }
2161
2162 int entry_frame_extension() const { return _argsize + (_argsize > 0 ? frame::metadata_words_at_top : 0); }
2163
2164 // top and bottom stack pointers
2165 intptr_t* sp() const { return ContinuationHelper::frame_align_pointer(_base - _thaw_size); }
2166 intptr_t* bottom_sp() const { return ContinuationHelper::frame_align_pointer(_base - entry_frame_extension()); }
2167
2168 // several operations operate on the totality of the stack being reconstructed,
2169 // including the metadata words
2170 intptr_t* top() const { return sp() - frame::metadata_words_at_bottom; }
2171 int total_size() const { return _thaw_size + frame::metadata_words_at_bottom; }
2172 };
2173
2174 inline void ThawBase::clear_chunk(stackChunkOop chunk) {
2175 chunk->set_sp(chunk->bottom());
2176 chunk->set_max_thawing_size(0);
2177 }
2178
2179 int ThawBase::remove_top_compiled_frame_from_chunk(stackChunkOop chunk, int &argsize) {
2180 bool empty = false;
2181 StackChunkFrameStream<ChunkFrames::CompiledOnly> f(chunk);
2182 DEBUG_ONLY(intptr_t* const chunk_sp = chunk->start_address() + chunk->sp();)
2183 assert(chunk_sp == f.sp(), "");
2184 assert(chunk_sp == f.unextended_sp(), "");
2185
2186 int frame_size = f.cb()->frame_size();
2187 argsize = f.stack_argsize();
2188 bool is_stub = f.is_stub();
2189
2190 f.next(SmallRegisterMap::instance, true /* stop */);
2191 empty = f.is_done();
2192 assert(!empty || argsize == chunk->argsize(), "");
2193
2194 assert(!is_stub || !empty, "runtime stub should have caller frame");
2195 if (is_stub) {
2196 // If we don't thaw the top compiled frame too, after restoring the saved
2197 // registers back in Java, we would hit the return barrier to thaw one more
2198 // frame effectively overwritting the restored registers during that call.
2199 f.get_cb();
2200 frame_size += f.cb()->frame_size();
2201 argsize = f.stack_argsize();
2202 f.next(SmallRegisterMap::instance, true /* stop */);
2203 empty = f.is_done();
2204 assert(!empty || argsize == chunk->argsize(), "");
2205 }
2206
2207 if (empty) {
2208 clear_chunk(chunk);
2209 } else {
2210 chunk->set_sp(chunk->sp() + frame_size);
2211 chunk->set_max_thawing_size(chunk->max_thawing_size() - frame_size);
2212 // We set chunk->pc to the return pc into the next frame
2213 chunk->set_pc(f.pc());
2214 #ifdef ASSERT
2215 {
2216 intptr_t* retaddr_slot = (chunk_sp
2217 + frame_size
2218 - frame::sender_sp_ret_address_offset());
2219 assert(f.pc() == ContinuationHelper::return_address_at(retaddr_slot),
2220 "unexpected pc");
2221 }
2222 #endif
2223 }
2224 assert(empty == chunk->is_empty(), "");
2225 // returns the size required to store the frame on stack, and because it is a
2226 // compiled frame, it must include a copy of the arguments passed by the caller
2227 return frame_size + argsize + frame::metadata_words_at_top;
2228 }
2229
2230 void ThawBase::copy_from_chunk(intptr_t* from, intptr_t* to, int size) {
2231 assert(to >= _top_stack_address, "overwrote past thawing space"
2232 " to: " INTPTR_FORMAT " top_address: " INTPTR_FORMAT, p2i(to), p2i(_top_stack_address));
2233 assert(to + size <= _cont.entrySP(), "overwrote past thawing space");
2234 _cont.tail()->copy_from_chunk_to_stack(from, to, size);
2235 CONT_JFR_ONLY(_jfr_info.record_size_copied(size);)
2236 }
2237
2238 void ThawBase::patch_return(intptr_t* sp, bool is_last) {
2239 log_develop_trace(continuations)("thaw_fast patching -- sp: " INTPTR_FORMAT, p2i(sp));
2240
2241 address pc = !is_last ? StubRoutines::cont_returnBarrier() : _cont.entryPC();
2242 ContinuationHelper::patch_return_address_at(
2243 sp - frame::sender_sp_ret_address_offset(),
2244 pc);
2245 }
2246
2247 template <typename ConfigT>
2248 NOINLINE intptr_t* Thaw<ConfigT>::thaw_fast(stackChunkOop chunk) {
2249 assert(chunk == _cont.tail(), "");
2250 assert(!chunk->has_mixed_frames(), "");
2251 assert(!chunk->requires_barriers(), "");
2252 assert(!chunk->has_bitmap(), "");
2253 assert(!_thread->is_interp_only_mode(), "");
2254
2255 LogTarget(Trace, continuations) lt;
2256 if (lt.develop_is_enabled()) {
2257 LogStream ls(lt);
2258 ls.print_cr("thaw_fast");
2259 chunk->print_on(true, &ls);
2260 }
2261
2262 // Below this heuristic, we thaw the whole chunk, above it we thaw just one frame.
2263 static const int threshold = 500; // words
2264
2265 const int full_chunk_size = chunk->stack_size() - chunk->sp(); // this initial size could be reduced if it's a partial thaw
2266 int argsize, thaw_size;
2267
2268 intptr_t* const chunk_sp = chunk->start_address() + chunk->sp();
2269
2270 bool partial, empty;
2271 if (LIKELY(!TEST_THAW_ONE_CHUNK_FRAME && (full_chunk_size < threshold))) {
2272 prefetch_chunk_pd(chunk->start_address(), full_chunk_size); // prefetch anticipating memcpy starting at highest address
2273
2274 partial = false;
2275 argsize = chunk->argsize(); // must be called *before* clearing the chunk
2276 clear_chunk(chunk);
2277 thaw_size = full_chunk_size;
2278 empty = true;
2279 } else { // thaw a single frame
2280 partial = true;
2281 thaw_size = remove_top_compiled_frame_from_chunk(chunk, argsize);
2282 empty = chunk->is_empty();
2283 }
2284
2285 // Are we thawing the last frame(s) in the continuation
2286 const bool is_last = empty && chunk->parent() == nullptr;
2287 assert(!is_last || argsize == 0, "");
2288
2289 log_develop_trace(continuations)("thaw_fast partial: %d is_last: %d empty: %d size: %d argsize: %d entrySP: " PTR_FORMAT,
2290 partial, is_last, empty, thaw_size, argsize, p2i(_cont.entrySP()));
2291
2292 ReconstructedStack rs(_cont.entrySP(), thaw_size, argsize);
2293
2294 // also copy metadata words at frame bottom
2295 copy_from_chunk(chunk_sp - frame::metadata_words_at_bottom, rs.top(), rs.total_size());
2296
2297 // update the ContinuationEntry
2298 _cont.set_argsize(argsize);
2299 log_develop_trace(continuations)("setting entry argsize: %d", _cont.argsize());
2300 assert(rs.bottom_sp() == _cont.entry()->bottom_sender_sp(), "");
2301
2302 // install the return barrier if not last frame, or the entry's pc if last
2303 patch_return(rs.bottom_sp(), is_last);
2304
2305 // insert the back links from callee to caller frames
2306 patch_caller_links(rs.top(), rs.top() + rs.total_size());
2307
2308 assert(is_last == _cont.is_empty(), "");
2309 assert(_cont.chunk_invariant(), "");
2310
2311 #if CONT_JFR
2312 EventContinuationThawFast e;
2313 if (e.should_commit()) {
2314 e.set_id(cast_from_oop<u8>(chunk));
2315 e.set_size(thaw_size << LogBytesPerWord);
2316 e.set_full(!partial);
2317 e.commit();
2318 }
2319 #endif
2320
2321 #ifdef ASSERT
2322 set_anchor(_thread, rs.sp());
2323 log_frames(_thread);
2324 if (LoomDeoptAfterThaw) {
2325 do_deopt_after_thaw(_thread);
2326 }
2327 clear_anchor(_thread);
2328 #endif
2329
2330 return rs.sp();
2331 }
2332
2333 inline bool ThawBase::seen_by_gc() {
2334 return _barriers || _cont.tail()->is_gc_mode();
2335 }
2336
2337 static inline void relativize_chunk_concurrently(stackChunkOop chunk) {
2338 #if INCLUDE_ZGC || INCLUDE_SHENANDOAHGC
2339 if (UseZGC || UseShenandoahGC) {
2340 chunk->relativize_derived_pointers_concurrently();
2341 }
2342 #endif
2343 }
2344
2345 template <typename ConfigT>
2346 NOINLINE intptr_t* Thaw<ConfigT>::thaw_slow(stackChunkOop chunk, Continuation::thaw_kind kind) {
2347 int preempt_kind;
2348 bool retry_fast_path = false;
2349
2350 bool preempted_case = _cont.is_preempted();
2351 if (preempted_case) {
2352 if (chunk->object_waiter() != nullptr) {
2353 assert(chunk->current_pending_monitor() != nullptr || chunk->current_waiting_monitor() != nullptr, "");
2354 return push_resume_monitor_operation(chunk);
2355 }
2356 retry_fast_path = true;
2357 relativize_chunk_concurrently(chunk);
2358 // Clear FLAGS_PREEMPTED after relativize_derived_pointers_concurrently()
2359 // is called to avoid racing with GC threads while modifying the flags.
2360 preempt_kind = chunk->get_and_clear_preempt_kind();
2361 } else {
2362 relativize_chunk_concurrently(chunk);
2363 }
2364
2365 // First thaw after freeze. If there were oops in the stacklock
2366 // during freeze, restore them now.
2367 if (chunk->lockstack_size() > 0) {
2368 assert(kind == Continuation::thaw_top || preempted_case, "");
2369 int lockStackSize = chunk->lockstack_size();
2370 assert(lockStackSize > 0, "should be");
2371
2372 oop tmp_lockstack[8];
2373 chunk->copy_lockstack(tmp_lockstack);
2374 _thread->lock_stack().move_from_address(tmp_lockstack, lockStackSize);
2375
2376 chunk->set_lockstack_size(0);
2377 chunk->set_has_lockstack(false);
2378 retry_fast_path = true;
2379 }
2380
2381 // Retry the fast path now that we possibly cleared the FLAG_HAS_LOCKSTACK
2382 // and FLAGS_PREEMPTED flags from the stackChunk.
2383 if (retry_fast_path && can_thaw_fast(chunk)) {
2384 intptr_t* sp = thaw_fast(chunk);
2385 if (preempted_case) {
2386 return handle_preempted_continuation(sp, preempt_kind, true /* fast_case */);
2387 }
2388 return sp;
2389 }
2390
2391 LogTarget(Trace, continuations) lt;
2392 if (lt.develop_is_enabled()) {
2393 LogStream ls(lt);
2394 ls.print_cr("thaw slow return_barrier: %d " INTPTR_FORMAT, kind, p2i(chunk));
2395 chunk->print_on(true, &ls);
2396 }
2397
2398 #if CONT_JFR
2399 EventContinuationThawSlow e;
2400 if (e.should_commit()) {
2401 e.set_id(cast_from_oop<u8>(_cont.continuation()));
2402 e.commit();
2403 }
2404 #endif
2405
2406 DEBUG_ONLY(_frames = 0;)
2407 _align_size = 0;
2408 bool is_return_barrier = kind != Continuation::thaw_top;
2409 int num_frames = (is_return_barrier ? 1 : 2);
2410
2411 _stream = StackChunkFrameStream<ChunkFrames::Mixed>(chunk);
2412 _top_unextended_sp_before_thaw = _stream.unextended_sp();
2413
2414 frame heap_frame = _stream.to_frame();
2415 if (lt.develop_is_enabled()) {
2416 LogStream ls(lt);
2417 ls.print_cr("top hframe before (thaw):");
2418 assert(heap_frame.is_heap_frame(), "should have created a relative frame");
2419 heap_frame.print_value_on(&ls, nullptr);
2420 }
2421
2422 frame caller; // the thawed caller on the stack
2423 recurse_thaw(heap_frame, caller, num_frames, preempted_case);
2424 finish_thaw(caller); // caller is now the topmost thawed frame
2425 _cont.write();
2426
2427 assert(_cont.chunk_invariant(), "");
2428
2429 JVMTI_ONLY(if (!is_return_barrier) invalidate_jvmti_stack(_thread));
2430
2431 _thread->set_cont_fastpath(_fastpath);
2432
2433 intptr_t* sp = caller.sp();
2434
2435 if (preempted_case) {
2436 return handle_preempted_continuation(sp, preempt_kind, false /* fast_case */);
2437 }
2438 return sp;
2439 }
2440
2441 void ThawBase::recurse_thaw(const frame& heap_frame, frame& caller, int num_frames, bool top_on_preempt_case) {
2442 log_develop_debug(continuations)("thaw num_frames: %d", num_frames);
2443 assert(!_cont.is_empty(), "no more frames");
2444 assert(num_frames > 0, "");
2445 assert(!heap_frame.is_empty(), "");
2446
2447 if (top_on_preempt_case && (heap_frame.is_native_frame() || heap_frame.is_runtime_frame())) {
2448 heap_frame.is_native_frame() ? recurse_thaw_native_frame(heap_frame, caller, 2) : recurse_thaw_stub_frame(heap_frame, caller, 2);
2449 } else if (!heap_frame.is_interpreted_frame()) {
2450 recurse_thaw_compiled_frame(heap_frame, caller, num_frames, false);
2451 } else {
2452 recurse_thaw_interpreted_frame(heap_frame, caller, num_frames);
2453 }
2454 }
2455
2456 template<typename FKind>
2457 bool ThawBase::recurse_thaw_java_frame(frame& caller, int num_frames) {
2458 assert(num_frames > 0, "");
2459
2460 DEBUG_ONLY(_frames++;)
2461
2462 int argsize = _stream.stack_argsize();
2463
2464 _stream.next(SmallRegisterMap::instance);
2465 assert(_stream.to_frame().is_empty() == _stream.is_done(), "");
2466
2467 // we never leave a compiled caller of an interpreted frame as the top frame in the chunk
2468 // as it makes detecting that situation and adjusting unextended_sp tricky
2469 if (num_frames == 1 && !_stream.is_done() && FKind::interpreted && _stream.is_compiled()) {
2470 log_develop_trace(continuations)("thawing extra compiled frame to not leave a compiled interpreted-caller at top");
2471 num_frames++;
2472 }
2473
2474 if (num_frames == 1 || _stream.is_done()) { // end recursion
2475 finalize_thaw(caller, FKind::interpreted ? 0 : argsize);
2476 return true; // bottom
2477 } else { // recurse
2478 recurse_thaw(_stream.to_frame(), caller, num_frames - 1, false /* top_on_preempt_case */);
2479 return false;
2480 }
2481 }
2482
2483 void ThawBase::finalize_thaw(frame& entry, int argsize) {
2484 stackChunkOop chunk = _cont.tail();
2485
2486 if (!_stream.is_done()) {
2487 assert(_stream.sp() >= chunk->sp_address(), "");
2488 chunk->set_sp(chunk->to_offset(_stream.sp()));
2489 chunk->set_pc(_stream.pc());
2490 } else {
2491 chunk->set_sp(chunk->bottom());
2492 chunk->set_pc(nullptr);
2493 }
2494 assert(_stream.is_done() == chunk->is_empty(), "");
2495
2496 int total_thawed = pointer_delta_as_int(_stream.unextended_sp(), _top_unextended_sp_before_thaw);
2497 chunk->set_max_thawing_size(chunk->max_thawing_size() - total_thawed);
2498
2499 _cont.set_argsize(argsize);
2500 entry = new_entry_frame();
2501
2502 assert(entry.sp() == _cont.entrySP(), "");
2503 assert(Continuation::is_continuation_enterSpecial(entry), "");
2504 assert(_cont.is_entry_frame(entry), "");
2505 }
2506
2507 inline void ThawBase::before_thaw_java_frame(const frame& hf, const frame& caller, bool bottom, int num_frame) {
2508 LogTarget(Trace, continuations) lt;
2509 if (lt.develop_is_enabled()) {
2510 LogStream ls(lt);
2511 ls.print_cr("======== THAWING FRAME: %d", num_frame);
2512 assert(hf.is_heap_frame(), "should be");
2513 hf.print_value_on(&ls, nullptr);
2514 }
2515 assert(bottom == _cont.is_entry_frame(caller), "bottom: %d is_entry_frame: %d", bottom, _cont.is_entry_frame(hf));
2516 }
2517
2518 inline void ThawBase::after_thaw_java_frame(const frame& f, bool bottom) {
2519 #ifdef ASSERT
2520 LogTarget(Trace, continuations) lt;
2521 if (lt.develop_is_enabled()) {
2522 LogStream ls(lt);
2523 ls.print_cr("thawed frame:");
2524 print_frame_layout(f, false, &ls); // f.print_on(&ls);
2525 }
2526 #endif
2527 }
2528
2529 inline void ThawBase::patch(frame& f, const frame& caller, bool bottom) {
2530 assert(!bottom || caller.fp() == _cont.entryFP(), "");
2531 if (bottom) {
2532 ContinuationHelper::Frame::patch_pc(caller, _cont.is_empty() ? caller.pc()
2533 : StubRoutines::cont_returnBarrier());
2534 } else {
2535 // caller might have been deoptimized during thaw but we've overwritten the return address when copying f from the heap.
2536 // If the caller is not deoptimized, pc is unchanged.
2537 ContinuationHelper::Frame::patch_pc(caller, caller.raw_pc());
2538 }
2539
2540 patch_pd(f, caller);
2541
2542 if (f.is_interpreted_frame()) {
2543 ContinuationHelper::InterpretedFrame::patch_sender_sp(f, caller);
2544 }
2545
2546 assert(!bottom || !_cont.is_empty() || Continuation::is_continuation_entry_frame(f, nullptr), "");
2547 assert(!bottom || (_cont.is_empty() != Continuation::is_cont_barrier_frame(f)), "");
2548 }
2549
2550 void ThawBase::clear_bitmap_bits(address start, address end) {
2551 assert(is_aligned(start, wordSize), "should be aligned: " PTR_FORMAT, p2i(start));
2552 assert(is_aligned(end, VMRegImpl::stack_slot_size), "should be aligned: " PTR_FORMAT, p2i(end));
2553
2554 // we need to clear the bits that correspond to arguments as they reside in the caller frame
2555 // or they will keep objects that are otherwise unreachable alive.
2556
2557 // Align `end` if UseCompressedOops is not set to avoid UB when calculating the bit index, since
2558 // `end` could be at an odd number of stack slots from `start`, i.e might not be oop aligned.
2559 // If that's the case the bit range corresponding to the last stack slot should not have bits set
2560 // anyways and we assert that before returning.
2561 address effective_end = UseCompressedOops ? end : align_down(end, wordSize);
2562 log_develop_trace(continuations)("clearing bitmap for " INTPTR_FORMAT " - " INTPTR_FORMAT, p2i(start), p2i(effective_end));
2563 stackChunkOop chunk = _cont.tail();
2564 chunk->bitmap().clear_range(chunk->bit_index_for(start), chunk->bit_index_for(effective_end));
2565 assert(effective_end == end || !chunk->bitmap().at(chunk->bit_index_for(effective_end)), "bit should not be set");
2566 }
2567
2568 intptr_t* ThawBase::handle_preempted_continuation(intptr_t* sp, int preempt_kind, bool fast_case) {
2569 assert(preempt_kind == freeze_on_wait || preempt_kind == freeze_on_monitorenter, "");
2570 frame top(sp);
2571 assert(top.pc() == *(address*)(sp - frame::sender_sp_ret_address_offset()), "");
2572
2573 assert(_cont.is_preempted(), "must be");
2574 _cont.set_preempted(false);
2575
2576 #if INCLUDE_JVMTI
2577 bool is_vthread = Continuation::continuation_scope(_cont.continuation()) == java_lang_VirtualThread::vthread_scope();
2578 if (is_vthread) {
2579 if (JvmtiVTMSTransitionDisabler::VTMS_notify_jvmti_events()) {
2580 jvmti_mount_end(_thread, _cont, top);
2581 } else {
2582 _thread->set_is_in_VTMS_transition(false);
2583 java_lang_Thread::set_is_in_VTMS_transition(_thread->vthread(), false);
2584 }
2585 }
2586 #endif
2587
2588 if (fast_case) {
2589 // If we thawed in the slow path the runtime stub/native wrapper frame already
2590 // has the correct fp (see ThawBase::new_stack_frame). On the fast path though,
2591 // we copied the original fp at the time of freeze which now will have to be fixed.
2592 assert(top.is_runtime_frame() || top.is_native_frame(), "");
2593 int fsize = top.cb()->frame_size();
2594 patch_pd(top, sp + fsize);
2595 }
2596
2597 if (preempt_kind == freeze_on_wait) {
2598 if (_thread->pending_interrupted_exception()) {
2599 throw_interrupted_exception(_thread, top);
2600 _thread->set_pending_interrupted_exception(false);
2601 }
2602 // Possibly update return pc on the top native wrapper frame so
2603 // that we resume execution at the right instruction.
2604 fix_native_wrapper_return_pc_pd(top);
2605 } else if (top.is_runtime_frame()) {
2606 // The continuation might now run on a different platform thread than the previous time so
2607 // we need to adjust the current thread saved in the stub frame before restoring registers.
2608 JavaThread** thread_addr = frame::saved_thread_address(top);
2609 if (thread_addr != nullptr) *thread_addr = _thread;
2610 }
2611 sp = push_resume_adapter(top);
2612 return sp;
2613 }
2614
2615 void ThawBase::throw_interrupted_exception(JavaThread* current, frame& top) {
2616 ContinuationWrapper::SafepointOp so(current, _cont);
2617 // Since we might safepoint set the anchor so that the stack can we walked.
2618 set_anchor(current, top.sp());
2619 JRT_BLOCK
2620 THROW(vmSymbols::java_lang_InterruptedException());
2621 JRT_BLOCK_END
2622 clear_anchor(current);
2623 }
2624
2625 NOINLINE void ThawBase::recurse_thaw_interpreted_frame(const frame& hf, frame& caller, int num_frames) {
2626 assert(hf.is_interpreted_frame(), "");
2627
2628 if (UNLIKELY(seen_by_gc())) {
2629 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance);
2630 }
2631
2632 const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::InterpretedFrame>(caller, num_frames);
2633
2634 DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2635
2636 _align_size += frame::align_wiggle; // possible added alignment for internal interpreted frame alignment om AArch64
2637
2638 frame f = new_stack_frame<ContinuationHelper::InterpretedFrame>(hf, caller, is_bottom_frame);
2639
2640 intptr_t* const stack_frame_top = f.sp() + frame::metadata_words_at_top;
2641 intptr_t* const stack_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(f);
2642 intptr_t* const heap_frame_top = hf.unextended_sp() + frame::metadata_words_at_top;
2643 intptr_t* const heap_frame_bottom = ContinuationHelper::InterpretedFrame::frame_bottom(hf);
2644
2645 assert(hf.is_heap_frame(), "should be");
2646 assert(!f.is_heap_frame(), "should not be");
2647
2648 const int fsize = pointer_delta_as_int(heap_frame_bottom, heap_frame_top);
2649 assert((stack_frame_bottom == stack_frame_top + fsize), "");
2650
2651 // Some architectures (like AArch64/PPC64/RISC-V) add padding between the locals and the fixed_frame to keep the fp 16-byte-aligned.
2652 // On those architectures we freeze the padding in order to keep the same fp-relative offsets in the fixed_frame.
2653 copy_from_chunk(heap_frame_top, stack_frame_top, fsize);
2654
2655 // Make sure the relativized locals is already set.
2656 assert(f.interpreter_frame_local_at(0) == stack_frame_bottom - 1, "invalid frame bottom");
2657
2658 derelativize_interpreted_frame_metadata(hf, f);
2659 patch(f, caller, is_bottom_frame);
2660
2661 assert(f.is_interpreted_frame_valid(_cont.thread()), "invalid thawed frame");
2662 assert(stack_frame_bottom <= ContinuationHelper::Frame::frame_top(caller), "");
2663
2664 CONT_JFR_ONLY(_jfr_info.record_interpreted_frame();)
2665
2666 maybe_set_fastpath(f.sp());
2667
2668 Method* m = hf.interpreter_frame_method();
2669 // For native frames we need to count parameters, possible alignment, plus the 2 extra words (temp oop/result handler).
2670 const int locals = !m->is_native() ? m->max_locals() : m->size_of_parameters() + frame::align_wiggle + 2;
2671
2672 if (!is_bottom_frame) {
2673 // can only fix caller once this frame is thawed (due to callee saved regs)
2674 _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance);
2675 } else if (_cont.tail()->has_bitmap() && locals > 0) {
2676 assert(hf.is_heap_frame(), "should be");
2677 address start = (address)(heap_frame_bottom - locals);
2678 address end = (address)heap_frame_bottom;
2679 clear_bitmap_bits(start, end);
2680 }
2681
2682 DEBUG_ONLY(after_thaw_java_frame(f, is_bottom_frame);)
2683 caller = f;
2684 }
2685
2686 void ThawBase::recurse_thaw_compiled_frame(const frame& hf, frame& caller, int num_frames, bool stub_caller) {
2687 assert(hf.is_compiled_frame(), "");
2688 assert(_cont.is_preempted() || !stub_caller, "stub caller not at preemption");
2689
2690 if (!stub_caller && UNLIKELY(seen_by_gc())) { // recurse_thaw_stub_frame already invoked our barriers with a full regmap
2691 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance);
2692 }
2693
2694 const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::CompiledFrame>(caller, num_frames);
2695
2696 DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2697
2698 assert(caller.sp() == caller.unextended_sp(), "");
2699
2700 if ((!is_bottom_frame && caller.is_interpreted_frame()) || (is_bottom_frame && Interpreter::contains(_cont.tail()->pc()))) {
2701 _align_size += frame::align_wiggle; // we add one whether or not we've aligned because we add it in recurse_freeze_compiled_frame
2702 }
2703
2704 // new_stack_frame must construct the resulting frame using hf.pc() rather than hf.raw_pc() because the frame is not
2705 // yet laid out in the stack, and so the original_pc is not stored in it.
2706 // As a result, f.is_deoptimized_frame() is always false and we must test hf to know if the frame is deoptimized.
2707 frame f = new_stack_frame<ContinuationHelper::CompiledFrame>(hf, caller, is_bottom_frame);
2708 intptr_t* const stack_frame_top = f.sp();
2709 intptr_t* const heap_frame_top = hf.unextended_sp();
2710
2711 const int added_argsize = (is_bottom_frame || caller.is_interpreted_frame()) ? hf.compiled_frame_stack_argsize() : 0;
2712 int fsize = ContinuationHelper::CompiledFrame::size(hf) + added_argsize;
2713 assert(fsize <= (int)(caller.unextended_sp() - f.unextended_sp()), "");
2714
2715 intptr_t* from = heap_frame_top - frame::metadata_words_at_bottom;
2716 intptr_t* to = stack_frame_top - frame::metadata_words_at_bottom;
2717 // copy metadata, except the metadata at the top of the (unextended) entry frame
2718 int sz = fsize + frame::metadata_words_at_bottom + (is_bottom_frame && added_argsize == 0 ? 0 : frame::metadata_words_at_top);
2719
2720 // If we're the bottom-most thawed frame, we're writing to within one word from entrySP
2721 // (we might have one padding word for alignment)
2722 assert(!is_bottom_frame || (_cont.entrySP() - 1 <= to + sz && to + sz <= _cont.entrySP()), "");
2723 assert(!is_bottom_frame || hf.compiled_frame_stack_argsize() != 0 || (to + sz && to + sz == _cont.entrySP()), "");
2724
2725 copy_from_chunk(from, to, sz); // copying good oops because we invoked barriers above
2726
2727 patch(f, caller, is_bottom_frame);
2728
2729 // f.is_deoptimized_frame() is always false and we must test hf.is_deoptimized_frame() (see comment above)
2730 assert(!f.is_deoptimized_frame(), "");
2731 if (hf.is_deoptimized_frame()) {
2732 maybe_set_fastpath(f.sp());
2733 } else if (_thread->is_interp_only_mode()
2734 || (_cont.is_preempted() && f.cb()->as_nmethod()->is_marked_for_deoptimization())) {
2735 // The caller of the safepoint stub when the continuation is preempted is not at a call instruction, and so
2736 // cannot rely on nmethod patching for deopt.
2737
2738 log_develop_trace(continuations)("Deoptimizing thawed frame");
2739 DEBUG_ONLY(ContinuationHelper::Frame::patch_pc(f, nullptr));
2740
2741 f.deoptimize(nullptr); // the null thread simply avoids the assertion in deoptimize which we're not set up for
2742 assert(f.is_deoptimized_frame(), "");
2743 assert(ContinuationHelper::Frame::is_deopt_return(f.raw_pc(), f), "");
2744 maybe_set_fastpath(f.sp());
2745 }
2746
2747 if (!is_bottom_frame) {
2748 // can only fix caller once this frame is thawed (due to callee saved regs); this happens on the stack
2749 _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance);
2750 } else if (_cont.tail()->has_bitmap() && added_argsize > 0) {
2751 address start = (address)(heap_frame_top + ContinuationHelper::CompiledFrame::size(hf) + frame::metadata_words_at_top);
2752 int stack_args_slots = f.cb()->as_nmethod()->num_stack_arg_slots(false /* rounded */);
2753 int argsize_in_bytes = stack_args_slots * VMRegImpl::stack_slot_size;
2754 clear_bitmap_bits(start, start + argsize_in_bytes);
2755 }
2756
2757 DEBUG_ONLY(after_thaw_java_frame(f, is_bottom_frame);)
2758 caller = f;
2759 }
2760
2761 void ThawBase::recurse_thaw_stub_frame(const frame& hf, frame& caller, int num_frames) {
2762 DEBUG_ONLY(_frames++;)
2763 bool is_bottom_frame = false;
2764
2765 if (UNLIKELY(seen_by_gc())) {
2766 // Process the stub's caller here since we might need the full map (if the stub was
2767 // generated on a poll on return we shouldn't need a full map).
2768 RegisterMap map(nullptr,
2769 RegisterMap::UpdateMap::include,
2770 RegisterMap::ProcessFrames::skip,
2771 RegisterMap::WalkContinuation::skip);
2772 map.set_include_argument_oops(false);
2773 _stream.next(&map);
2774 if (!_stream.is_done()) {
2775 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, &map);
2776 }
2777 } else {
2778 _stream.next(SmallRegisterMap::instance);
2779 }
2780
2781 if (_stream.is_done()) {
2782 finalize_thaw(caller, 0);
2783 is_bottom_frame = true;
2784 } else {
2785 frame f = _stream.to_frame();
2786 if (f.is_interpreted_frame()) {
2787 recurse_thaw_interpreted_frame(f, caller, num_frames);
2788 } else {
2789 recurse_thaw_compiled_frame(f, caller, num_frames, true);
2790 }
2791 }
2792
2793 assert(!is_bottom_frame || !_cont.is_empty(), "");
2794 assert(caller.sp() == caller.unextended_sp(), "");
2795 assert(!caller.is_native_frame() || (is_bottom_frame && Continuation::is_continuation_enterSpecial(caller)), "caller should't be native except for enterSpecial case");
2796
2797 DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2798
2799 if ((!is_bottom_frame && caller.is_interpreted_frame()) || (is_bottom_frame && Interpreter::contains(_cont.tail()->pc()))) {
2800 _align_size += frame::align_wiggle; // we add one whether or not we've aligned because we add it in recurse_freeze_stub_frame
2801 }
2802
2803 frame f = new_stack_frame<ContinuationHelper::StubFrame>(hf, caller, false);
2804 intptr_t* stack_frame_top = f.sp();
2805 intptr_t* heap_frame_top = hf.sp();
2806 int fsize = ContinuationHelper::StubFrame::size(hf);
2807
2808 copy_from_chunk(heap_frame_top - frame::metadata_words, stack_frame_top - frame::metadata_words,
2809 fsize + frame::metadata_words);
2810
2811 patch(f, caller, is_bottom_frame);
2812
2813 if (!is_bottom_frame) {
2814 // can only fix caller once this frame is thawed (due to callee saved regs)
2815 RegisterMap map(nullptr,
2816 RegisterMap::UpdateMap::include,
2817 RegisterMap::ProcessFrames::skip,
2818 RegisterMap::WalkContinuation::skip);
2819 map.set_include_argument_oops(false);
2820 f.oop_map()->update_register_map(&f, &map);
2821 ContinuationHelper::update_register_map_with_callee(caller, &map);
2822 _cont.tail()->fix_thawed_frame(caller, &map);
2823 }
2824
2825 DEBUG_ONLY(after_thaw_java_frame(f, is_bottom_frame);)
2826 caller = f;
2827 }
2828
2829 void ThawBase::recurse_thaw_native_frame(const frame& hf, frame& caller, int num_frames) {
2830 assert(hf.is_native_frame(), "");
2831 assert(_cont.is_preempted() && hf.cb()->as_nmethod()->method()->is_object_wait0(), "");
2832
2833 if (UNLIKELY(seen_by_gc())) { // recurse_thaw_stub_frame already invoked our barriers with a full regmap
2834 _cont.tail()->do_barriers<stackChunkOopDesc::BarrierType::Store>(_stream, SmallRegisterMap::instance);
2835 }
2836
2837 const bool is_bottom_frame = recurse_thaw_java_frame<ContinuationHelper::NativeFrame>(caller, num_frames);
2838 assert(!is_bottom_frame, "");
2839
2840 DEBUG_ONLY(before_thaw_java_frame(hf, caller, is_bottom_frame, num_frames);)
2841
2842 assert(caller.sp() == caller.unextended_sp(), "");
2843
2844 if (caller.is_interpreted_frame()) {
2845 _align_size += frame::align_wiggle; // we add one whether or not we've aligned because we add it in recurse_freeze_compiled_frame
2846 }
2847
2848 // new_stack_frame must construct the resulting frame using hf.pc() rather than hf.raw_pc() because the frame is not
2849 // yet laid out in the stack, and so the original_pc is not stored in it.
2850 // As a result, f.is_deoptimized_frame() is always false and we must test hf to know if the frame is deoptimized.
2851 frame f = new_stack_frame<ContinuationHelper::NativeFrame>(hf, caller, false /* bottom */);
2852 intptr_t* const stack_frame_top = f.sp();
2853 intptr_t* const heap_frame_top = hf.unextended_sp();
2854
2855 int fsize = ContinuationHelper::NativeFrame::size(hf);
2856 assert(fsize <= (int)(caller.unextended_sp() - f.unextended_sp()), "");
2857
2858 intptr_t* from = heap_frame_top - frame::metadata_words_at_bottom;
2859 intptr_t* to = stack_frame_top - frame::metadata_words_at_bottom;
2860 int sz = fsize + frame::metadata_words_at_bottom;
2861
2862 copy_from_chunk(from, to, sz); // copying good oops because we invoked barriers above
2863
2864 patch(f, caller, false /* bottom */);
2865
2866 // f.is_deoptimized_frame() is always false and we must test hf.is_deoptimized_frame() (see comment above)
2867 assert(!f.is_deoptimized_frame(), "");
2868 assert(!hf.is_deoptimized_frame(), "");
2869 assert(!f.cb()->as_nmethod()->is_marked_for_deoptimization(), "");
2870
2871 // can only fix caller once this frame is thawed (due to callee saved regs); this happens on the stack
2872 _cont.tail()->fix_thawed_frame(caller, SmallRegisterMap::instance);
2873
2874 DEBUG_ONLY(after_thaw_java_frame(f, false /* bottom */);)
2875 caller = f;
2876 }
2877
2878 void ThawBase::finish_thaw(frame& f) {
2879 stackChunkOop chunk = _cont.tail();
2880
2881 if (chunk->is_empty()) {
2882 // Only remove chunk from list if it can't be reused for another freeze
2883 if (seen_by_gc()) {
2884 _cont.set_tail(chunk->parent());
2885 } else {
2886 chunk->set_has_mixed_frames(false);
2887 }
2888 chunk->set_max_thawing_size(0);
2889 } else {
2890 chunk->set_max_thawing_size(chunk->max_thawing_size() - _align_size);
2891 }
2892 assert(chunk->is_empty() == (chunk->max_thawing_size() == 0), "");
2893
2894 if (!is_aligned(f.sp(), frame::frame_alignment)) {
2895 assert(f.is_interpreted_frame(), "");
2896 f.set_sp(align_down(f.sp(), frame::frame_alignment));
2897 }
2898 push_return_frame(f);
2899 chunk->fix_thawed_frame(f, SmallRegisterMap::instance); // can only fix caller after push_return_frame (due to callee saved regs)
2900
2901 assert(_cont.is_empty() == _cont.last_frame().is_empty(), "");
2902
2903 log_develop_trace(continuations)("thawed %d frames", _frames);
2904
2905 LogTarget(Trace, continuations) lt;
2906 if (lt.develop_is_enabled()) {
2907 LogStream ls(lt);
2908 ls.print_cr("top hframe after (thaw):");
2909 _cont.last_frame().print_value_on(&ls, nullptr);
2910 }
2911 }
2912
2913 void ThawBase::push_return_frame(frame& f) { // see generate_cont_thaw
2914 assert(!f.is_compiled_frame() || f.is_deoptimized_frame() == f.cb()->as_nmethod()->is_deopt_pc(f.raw_pc()), "");
2915 assert(!f.is_compiled_frame() || f.is_deoptimized_frame() == (f.pc() != f.raw_pc()), "");
2916
2917 LogTarget(Trace, continuations) lt;
2918 if (lt.develop_is_enabled()) {
2919 LogStream ls(lt);
2920 ls.print_cr("push_return_frame");
2921 f.print_value_on(&ls, nullptr);
2922 }
2923
2924 assert(f.sp() - frame::metadata_words_at_bottom >= _top_stack_address, "overwrote past thawing space"
2925 " to: " INTPTR_FORMAT " top_address: " INTPTR_FORMAT, p2i(f.sp() - frame::metadata_words), p2i(_top_stack_address));
2926 ContinuationHelper::Frame::patch_pc(f, f.raw_pc()); // in case we want to deopt the frame in a full transition, this is checked.
2927 ContinuationHelper::push_pd(f);
2928
2929 assert(ContinuationHelper::Frame::assert_frame_laid_out(f), "");
2930 }
2931
2932 // returns new top sp
2933 // called after preparations (stack overflow check and making room)
2934 template<typename ConfigT>
2935 static inline intptr_t* thaw_internal(JavaThread* thread, const Continuation::thaw_kind kind) {
2936 assert(thread == JavaThread::current(), "Must be current thread");
2937
2938 CONT_JFR_ONLY(EventContinuationThaw event;)
2939
2940 log_develop_trace(continuations)("~~~~ thaw kind: %d sp: " INTPTR_FORMAT, kind, p2i(thread->last_continuation()->entry_sp()));
2941
2942 ContinuationEntry* entry = thread->last_continuation();
2943 assert(entry != nullptr, "");
2944 oop oopCont = entry->cont_oop(thread);
2945
2946 assert(!jdk_internal_vm_Continuation::done(oopCont), "");
2947 assert(oopCont == get_continuation(thread), "");
2948 verify_continuation(oopCont);
2949
2950 assert(entry->is_virtual_thread() == (entry->scope(thread) == java_lang_VirtualThread::vthread_scope()), "");
2951
2952 ContinuationWrapper cont(thread, oopCont);
2953 log_develop_debug(continuations)("THAW #" INTPTR_FORMAT " " INTPTR_FORMAT, cont.hash(), p2i((oopDesc*)oopCont));
2954
2955 #ifdef ASSERT
2956 set_anchor_to_entry(thread, cont.entry());
2957 log_frames(thread);
2958 clear_anchor(thread);
2959 #endif
2960
2961 Thaw<ConfigT> thw(thread, cont);
2962 intptr_t* const sp = thw.thaw(kind);
2963 assert(is_aligned(sp, frame::frame_alignment), "");
2964
2965 DEBUG_ONLY(log_frames_after_thaw(thread, cont, sp);)
2966
2967 CONT_JFR_ONLY(thw.jfr_info().post_jfr_event(&event, cont.continuation(), thread);)
2968
2969 verify_continuation(cont.continuation());
2970 log_develop_debug(continuations)("=== End of thaw #" INTPTR_FORMAT, cont.hash());
2971
2972 return sp;
2973 }
2974
2975 #ifdef ASSERT
2976 static void do_deopt_after_thaw(JavaThread* thread) {
2977 int i = 0;
2978 StackFrameStream fst(thread, true, false);
2979 fst.register_map()->set_include_argument_oops(false);
2980 ContinuationHelper::update_register_map_with_callee(*fst.current(), fst.register_map());
2981 for (; !fst.is_done(); fst.next()) {
2982 if (fst.current()->cb()->is_nmethod()) {
2983 nmethod* nm = fst.current()->cb()->as_nmethod();
2984 if (!nm->method()->is_continuation_native_intrinsic()) {
2985 nm->make_deoptimized();
2986 }
2987 }
2988 }
2989 }
2990
2991 class ThawVerifyOopsClosure: public OopClosure {
2992 intptr_t* _p;
2993 outputStream* _st;
2994 bool is_good_oop(oop o) {
2995 return dbg_is_safe(o, -1) && dbg_is_safe(o->klass(), -1) && oopDesc::is_oop(o) && o->klass()->is_klass();
2996 }
2997 public:
2998 ThawVerifyOopsClosure(outputStream* st) : _p(nullptr), _st(st) {}
2999 intptr_t* p() { return _p; }
3000 void reset() { _p = nullptr; }
3001
3002 virtual void do_oop(oop* p) {
3003 oop o = *p;
3004 if (o == nullptr || is_good_oop(o)) {
3005 return;
3006 }
3007 _p = (intptr_t*)p;
3008 _st->print_cr("*** non-oop " PTR_FORMAT " found at " PTR_FORMAT, p2i(*p), p2i(p));
3009 }
3010 virtual void do_oop(narrowOop* p) {
3011 oop o = RawAccess<>::oop_load(p);
3012 if (o == nullptr || is_good_oop(o)) {
3013 return;
3014 }
3015 _p = (intptr_t*)p;
3016 _st->print_cr("*** (narrow) non-oop %x found at " PTR_FORMAT, (int)(*p), p2i(p));
3017 }
3018 };
3019
3020 static bool do_verify_after_thaw(JavaThread* thread, stackChunkOop chunk, outputStream* st) {
3021 assert(thread->has_last_Java_frame(), "");
3022
3023 ResourceMark rm;
3024 ThawVerifyOopsClosure cl(st);
3025 NMethodToOopClosure cf(&cl, false);
3026
3027 StackFrameStream fst(thread, true, false);
3028 fst.register_map()->set_include_argument_oops(false);
3029 ContinuationHelper::update_register_map_with_callee(*fst.current(), fst.register_map());
3030 for (; !fst.is_done() && !Continuation::is_continuation_enterSpecial(*fst.current()); fst.next()) {
3031 if (fst.current()->cb()->is_nmethod() && fst.current()->cb()->as_nmethod()->is_marked_for_deoptimization()) {
3032 st->print_cr(">>> do_verify_after_thaw deopt");
3033 fst.current()->deoptimize(nullptr);
3034 fst.current()->print_on(st);
3035 }
3036
3037 fst.current()->oops_do(&cl, &cf, fst.register_map());
3038 if (cl.p() != nullptr) {
3039 frame fr = *fst.current();
3040 st->print_cr("Failed for frame barriers: %d",chunk->requires_barriers());
3041 fr.print_on(st);
3042 if (!fr.is_interpreted_frame()) {
3043 st->print_cr("size: %d argsize: %d",
3044 ContinuationHelper::NonInterpretedUnknownFrame::size(fr),
3045 ContinuationHelper::NonInterpretedUnknownFrame::stack_argsize(fr));
3046 }
3047 VMReg reg = fst.register_map()->find_register_spilled_here(cl.p(), fst.current()->sp());
3048 if (reg != nullptr) {
3049 st->print_cr("Reg %s %d", reg->name(), reg->is_stack() ? (int)reg->reg2stack() : -99);
3050 }
3051 cl.reset();
3052 DEBUG_ONLY(thread->print_frame_layout();)
3053 if (chunk != nullptr) {
3054 chunk->print_on(true, st);
3055 }
3056 return false;
3057 }
3058 }
3059 return true;
3060 }
3061
3062 static void log_frames(JavaThread* thread) {
3063 const static int show_entry_callers = 100;
3064 LogTarget(Trace, continuations) lt;
3065 if (!lt.develop_is_enabled()) {
3066 return;
3067 }
3068 LogStream ls(lt);
3069
3070 ls.print_cr("------- frames --------- for thread " INTPTR_FORMAT, p2i(thread));
3071 if (!thread->has_last_Java_frame()) {
3072 ls.print_cr("NO ANCHOR!");
3073 }
3074
3075 RegisterMap map(thread,
3076 RegisterMap::UpdateMap::include,
3077 RegisterMap::ProcessFrames::include,
3078 RegisterMap::WalkContinuation::skip);
3079 map.set_include_argument_oops(false);
3080
3081 if (false) {
3082 for (frame f = thread->last_frame(); !f.is_entry_frame(); f = f.sender(&map)) {
3083 f.print_on(&ls);
3084 }
3085 } else {
3086 map.set_skip_missing(true);
3087 ResetNoHandleMark rnhm;
3088 ResourceMark rm;
3089 HandleMark hm(Thread::current());
3090 FrameValues values;
3091
3092 int i = 0;
3093 int post_entry = -1;
3094 for (frame f = thread->last_frame(); !f.is_first_frame(); f = f.sender(&map), i++) {
3095 f.describe(values, i, &map, i == 0);
3096 if (post_entry >= 0 || Continuation::is_continuation_enterSpecial(f))
3097 post_entry++;
3098 if (post_entry >= show_entry_callers)
3099 break;
3100 }
3101 values.print_on(thread, &ls);
3102 }
3103
3104 ls.print_cr("======= end frames =========");
3105 }
3106
3107 static void log_frames_after_thaw(JavaThread* thread, ContinuationWrapper& cont, intptr_t* sp) {
3108 intptr_t* sp0 = sp;
3109 address pc0 = *(address*)(sp - frame::sender_sp_ret_address_offset());
3110 bool use_cont_entry = false;
3111
3112 // Preemption cases need to use and adjusted version of sp.
3113 if (pc0 == Interpreter::cont_resume_interpreter_adapter() ||
3114 pc0 == StubRoutines::cont_resume_compiler_adapter()) {
3115 // Resuming after being preempted case. We skip the adapter pushed
3116 // into the stack (see push_preempt_rerun_adapter()).
3117 sp0 += frame::metadata_words;
3118
3119 if (pc0 == StubRoutines::cont_resume_compiler_adapter()) {
3120 address pc1 = *(address*)(sp0 - frame::sender_sp_ret_address_offset());
3121 if (pc1 == SharedRuntime::native_frame_resume_entry()) {
3122 // When top is the compiled native wrapper (Object.wait()) the pc
3123 // would have been modified from its original value to return to
3124 // the correct place. But that means we won't find the oopMap for
3125 // that fixed pc when getting the sender which will trigger asserts.
3126 // So just start walking the frames from the sender instead.
3127 CodeBlob* cb = CodeCache::find_blob(pc1);
3128 assert(cb->as_nmethod()->method()->is_object_wait0(), "");
3129 sp0 += cb->frame_size();
3130 if (sp0 == cont.entrySP()) {
3131 // sp0[-1] will be the return barrier pc. This is a stub, i.e. associated
3132 // codeblob has _frame_size = 0. Force using cont.entryPC() to avoid
3133 // asserts while trying to get the sender frame.
3134 use_cont_entry = true;
3135 }
3136 }
3137 #ifdef AARCH64
3138 else {
3139 // Monitorenter case returning to c2 runtime stub requires extra
3140 // adjustment on aarch64 (see push_preempt_rerun_adapter()).
3141 address pc1 = *(address*)(sp0 - frame::sender_sp_ret_address_offset());
3142 CodeBlob* cb = CodeCache::find_blob(pc1);
3143 assert(cb != nullptr, "should be either c1 or c2 runtime stub");
3144 if (cb->frame_size() == 2) {
3145 sp0 += frame::metadata_words;
3146 }
3147 }
3148 #endif
3149 }
3150 } else if (pc0 == StubRoutines::cont_resume_monitor_operation()) {
3151 // Redoing monitor operation after being preempted case. We skip
3152 // the adapter + data pushed into the stack (see push_resume_monitor_operation()).
3153 use_cont_entry = true;
3154 }
3155
3156 set_anchor(thread, use_cont_entry ? cont.entrySP() : sp0, use_cont_entry ? cont.entryPC() : nullptr);
3157 log_frames(thread);
3158 if (LoomVerifyAfterThaw) {
3159 assert(do_verify_after_thaw(thread, cont.tail(), tty), "");
3160 }
3161 assert(ContinuationEntry::assert_entry_frame_laid_out(thread), "");
3162 clear_anchor(thread);
3163
3164 LogTarget(Trace, continuations) lt;
3165 if (lt.develop_is_enabled()) {
3166 LogStream ls(lt);
3167 ls.print_cr("Jumping to frame (thaw):");
3168 frame(sp).print_value_on(&ls, nullptr);
3169 }
3170 }
3171 #endif // ASSERT
3172
3173 #include CPU_HEADER_INLINE(continuationFreezeThaw)
3174
3175 #ifdef ASSERT
3176 static void print_frame_layout(const frame& f, bool callee_complete, outputStream* st) {
3177 ResourceMark rm;
3178 FrameValues values;
3179 assert(f.get_cb() != nullptr, "");
3180 RegisterMap map(f.is_heap_frame() ?
3181 nullptr :
3182 JavaThread::current(),
3183 RegisterMap::UpdateMap::include,
3184 RegisterMap::ProcessFrames::skip,
3185 RegisterMap::WalkContinuation::skip);
3186 map.set_include_argument_oops(false);
3187 map.set_skip_missing(true);
3188 if (callee_complete) {
3189 frame::update_map_with_saved_link(&map, ContinuationHelper::Frame::callee_link_address(f));
3190 }
3191 const_cast<frame&>(f).describe(values, 0, &map, true);
3192 values.print_on(static_cast<JavaThread*>(nullptr), st);
3193 }
3194 #endif
3195
3196 static address thaw_entry = nullptr;
3197 static address freeze_entry = nullptr;
3198 static address freeze_preempt_entry = nullptr;
3199
3200 address Continuation::thaw_entry() {
3201 return ::thaw_entry;
3202 }
3203
3204 address Continuation::freeze_entry() {
3205 return ::freeze_entry;
3206 }
3207
3208 address Continuation::freeze_preempt_entry() {
3209 return ::freeze_preempt_entry;
3210 }
3211
3212 class ConfigResolve {
3213 public:
3214 static void resolve() { resolve_compressed(); }
3215
3216 static void resolve_compressed() {
3217 UseCompressedOops ? resolve_gc<true>()
3218 : resolve_gc<false>();
3219 }
3220
3221 private:
3222 template <bool use_compressed>
3223 static void resolve_gc() {
3224 BarrierSet* bs = BarrierSet::barrier_set();
3225 assert(bs != nullptr, "freeze/thaw invoked before BarrierSet is set");
3226 switch (bs->kind()) {
3227 #define BARRIER_SET_RESOLVE_BARRIER_CLOSURE(bs_name) \
3228 case BarrierSet::bs_name: { \
3229 resolve<use_compressed, typename BarrierSet::GetType<BarrierSet::bs_name>::type>(); \
3230 } \
3231 break;
3232 FOR_EACH_CONCRETE_BARRIER_SET_DO(BARRIER_SET_RESOLVE_BARRIER_CLOSURE)
3233 #undef BARRIER_SET_RESOLVE_BARRIER_CLOSURE
3234
3235 default:
3236 fatal("BarrierSet resolving not implemented");
3237 };
3238 }
3239
3240 template <bool use_compressed, typename BarrierSetT>
3241 static void resolve() {
3242 typedef Config<use_compressed ? oop_kind::NARROW : oop_kind::WIDE, BarrierSetT> SelectedConfigT;
3243
3244 freeze_entry = (address)freeze<SelectedConfigT>;
3245 freeze_preempt_entry = (address)SelectedConfigT::freeze_preempt;
3246
3247 // If we wanted, we could templatize by kind and have three different thaw entries
3248 thaw_entry = (address)thaw<SelectedConfigT>;
3249 }
3250 };
3251
3252 void Continuation::init() {
3253 ConfigResolve::resolve();
3254 }