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/*
* Copyright (c) 2018, 2022, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
#include "precompiled.hpp"
#include "classfile/vmSymbols.hpp"
#include "gc/shared/barrierSetNMethod.hpp"
#include "oops/method.inline.hpp"
#include "runtime/arguments.hpp"
#include "runtime/continuation.hpp"
#include "runtime/continuationEntry.inline.hpp"
#include "runtime/continuationHelper.inline.hpp"
#include "runtime/continuationJavaClasses.inline.hpp"
#include "runtime/continuationWrapper.inline.hpp"
#include "runtime/interfaceSupport.inline.hpp"
#include "runtime/javaThread.inline.hpp"
#include "runtime/osThread.hpp"
#include "runtime/vframe.inline.hpp"
#include "runtime/vframe_hp.hpp"
// defined in continuationFreezeThaw.cpp
extern "C" jint JNICALL CONT_isPinned0(JNIEnv* env, jobject cont_scope);
JVM_ENTRY(void, CONT_pin(JNIEnv* env, jclass cls)) {
if (!Continuation::pin(JavaThread::thread_from_jni_environment(env))) {
THROW_MSG(vmSymbols::java_lang_IllegalStateException(), "pin overflow");
}
}
JVM_END
JVM_ENTRY(void, CONT_unpin(JNIEnv* env, jclass cls)) {
if (!Continuation::unpin(JavaThread::thread_from_jni_environment(env))) {
THROW_MSG(vmSymbols::java_lang_IllegalStateException(), "pin underflow");
}
}
JVM_END
#ifndef PRODUCT
static jlong java_tid(JavaThread* thread) {
return java_lang_Thread::thread_id(thread->threadObj());
}
#endif
ContinuationEntry* Continuation::get_continuation_entry_for_continuation(JavaThread* thread, oop continuation) {
if (thread == nullptr || continuation == nullptr) {
return nullptr;
}
for (ContinuationEntry* entry = thread->last_continuation(); entry != nullptr; entry = entry->parent()) {
if (continuation == entry->cont_oop(thread)) {
return entry;
}
}
return nullptr;
}
static bool is_on_stack(JavaThread* thread, const ContinuationEntry* entry) {
if (entry == nullptr) {
return false;
}
assert(thread->is_in_full_stack((address)entry), "");
return true;
// return false if called when transitioning to Java on return from freeze
// return !thread->has_last_Java_frame() || thread->last_Java_sp() < cont->entry_sp();
}
bool Continuation::is_continuation_mounted(JavaThread* thread, oop continuation) {
return is_on_stack(thread, get_continuation_entry_for_continuation(thread, continuation));
}
// When walking the virtual stack, this method returns true
// iff the frame is a thawed continuation frame whose
// caller is still frozen on the h-stack.
// The continuation object can be extracted from the thread.
bool Continuation::is_cont_barrier_frame(const frame& f) {
assert(f.is_interpreted_frame() || f.cb() != nullptr, "");
if (!Continuations::enabled()) return false;
return is_return_barrier_entry(f.is_interpreted_frame() ? ContinuationHelper::InterpretedFrame::return_pc(f)
: ContinuationHelper::CompiledFrame::return_pc(f));
}
bool Continuation::is_return_barrier_entry(const address pc) {
if (!Continuations::enabled()) return false;
return pc == StubRoutines::cont_returnBarrier();
}
bool Continuation::is_continuation_enterSpecial(const frame& f) {
if (f.cb() == nullptr || !f.cb()->is_compiled()) {
return false;
}
Method* m = f.cb()->as_compiled_method()->method();
return (m != nullptr && m->is_continuation_enter_intrinsic());
}
bool Continuation::is_continuation_entry_frame(const frame& f, const RegisterMap *map) {
// we can do this because the entry frame is never inlined
Method* m = (map != nullptr && map->in_cont() && f.is_interpreted_frame())
? map->stack_chunk()->interpreter_frame_method(f)
: ContinuationHelper::Frame::frame_method(f);
return m != nullptr && m->intrinsic_id() == vmIntrinsics::_Continuation_enter;
}
// The parameter `sp` should be the actual sp and not the unextended sp because at
// least on PPC64 unextended_sp < sp is possible as interpreted frames are trimmed
// to the actual size of the expression stack before calls. The problem there is
// that even unextended_sp < entry_sp < sp is possible for an interpreted frame.
static inline bool is_sp_in_continuation(const ContinuationEntry* entry, intptr_t* const sp) {
// entry_sp() returns the unextended_sp which is always greater or equal to the actual sp
return entry->entry_sp() > sp;
}
bool Continuation::is_frame_in_continuation(const ContinuationEntry* entry, const frame& f) {
return is_sp_in_continuation(entry, f.sp());
}
ContinuationEntry* Continuation::get_continuation_entry_for_sp(JavaThread* thread, intptr_t* const sp) {
assert(thread != nullptr, "");
ContinuationEntry* entry = thread->last_continuation();
while (entry != nullptr && !is_sp_in_continuation(entry, sp)) {
entry = entry->parent();
}
return entry;
}
ContinuationEntry* Continuation::get_continuation_entry_for_entry_frame(JavaThread* thread, const frame& f) {
assert(is_continuation_enterSpecial(f), "");
ContinuationEntry* entry = (ContinuationEntry*)f.unextended_sp();
assert(entry == get_continuation_entry_for_sp(thread, f.sp()-2), "mismatched entry");
return entry;
}
bool Continuation::is_frame_in_continuation(JavaThread* thread, const frame& f) {
return f.is_heap_frame() || (get_continuation_entry_for_sp(thread, f.sp()) != nullptr);
}
static frame continuation_top_frame(const ContinuationWrapper& cont, RegisterMap* map) {
stackChunkOop chunk = cont.last_nonempty_chunk();
map->set_stack_chunk(chunk);
return chunk != nullptr ? chunk->top_frame(map) : frame();
}
bool Continuation::has_last_Java_frame(oop continuation, frame* frame, RegisterMap* map) {
ContinuationWrapper cont(continuation);
if (!cont.is_empty()) {
*frame = continuation_top_frame(cont, map);
return true;
} else {
return false;
}
}
frame Continuation::last_frame(oop continuation, RegisterMap *map) {
assert(map != nullptr, "a map must be given");
return continuation_top_frame(ContinuationWrapper(continuation), map);
}
frame Continuation::top_frame(const frame& callee, RegisterMap* map) {
assert(map != nullptr, "");
ContinuationEntry* ce = get_continuation_entry_for_sp(map->thread(), callee.sp());
assert(ce != nullptr, "");
oop continuation = ce->cont_oop(map->thread());
ContinuationWrapper cont(continuation);
return continuation_top_frame(cont, map);
}
javaVFrame* Continuation::last_java_vframe(Handle continuation, RegisterMap *map) {
assert(map != nullptr, "a map must be given");
if (!ContinuationWrapper(continuation()).is_empty()) {
frame f = last_frame(continuation(), map);
for (vframe* vf = vframe::new_vframe(&f, map, nullptr); vf; vf = vf->sender()) {
if (vf->is_java_frame()) {
return javaVFrame::cast(vf);
}
}
}
return nullptr;
}
frame Continuation::continuation_parent_frame(RegisterMap* map) {
assert(map->in_cont(), "");
ContinuationWrapper cont(map);
assert(map->thread() != nullptr || !cont.is_mounted(), "");
log_develop_trace(continuations)("continuation_parent_frame");
if (map->update_map()) {
// we need to register the link address for the entry frame
if (cont.entry() != nullptr) {
cont.entry()->update_register_map(map);
} else {
map->clear();
}
}
if (!cont.is_mounted()) { // When we're walking an unmounted continuation and reached the end
oop parent = jdk_internal_vm_Continuation::parent(cont.continuation());
stackChunkOop chunk = parent != nullptr ? ContinuationWrapper(parent).last_nonempty_chunk() : nullptr;
if (chunk != nullptr) {
return chunk->top_frame(map);
}
map->set_stack_chunk(nullptr);
return frame();
}
map->set_stack_chunk(nullptr);
#if (defined(X86) || defined(AARCH64) || defined(RISCV64) || defined(PPC64)) && !defined(ZERO)
frame sender(cont.entrySP(), cont.entryFP(), cont.entryPC());
#else
frame sender = frame();
Unimplemented();
#endif
return sender;
}
oop Continuation::continuation_scope(oop continuation) {
return continuation != nullptr ? jdk_internal_vm_Continuation::scope(continuation) : nullptr;
}
bool Continuation::is_scope_bottom(oop cont_scope, const frame& f, const RegisterMap* map) {
if (cont_scope == nullptr || !is_continuation_entry_frame(f, map)) {
return false;
}
oop continuation;
if (map->in_cont()) {
continuation = map->cont();
} else {
ContinuationEntry* ce = get_continuation_entry_for_sp(map->thread(), f.sp());
if (ce == nullptr) {
return false;
}
continuation = ce->cont_oop(map->thread());
}
if (continuation == nullptr) {
return false;
}
oop sc = continuation_scope(continuation);
assert(sc != nullptr, "");
return sc == cont_scope;
}
bool Continuation::is_in_usable_stack(address addr, const RegisterMap* map) {
ContinuationWrapper cont(map);
stackChunkOop chunk = cont.find_chunk_by_address(addr);
return chunk != nullptr ? chunk->is_usable_in_chunk(addr) : false;
}
bool Continuation::pin(JavaThread* current) {
ContinuationEntry* ce = current->last_continuation();
if (ce == nullptr) {
return true; // no continuation mounted
}
return ce->pin();
}
bool Continuation::unpin(JavaThread* current) {
ContinuationEntry* ce = current->last_continuation();
if (ce == nullptr) {
return true; // no continuation mounted
}
return ce->unpin();
}
frame Continuation::continuation_bottom_sender(JavaThread* thread, const frame& callee, intptr_t* sender_sp) {
assert (thread != nullptr, "");
ContinuationEntry* ce = get_continuation_entry_for_sp(thread, callee.sp());
assert(ce != nullptr, "callee.sp(): " INTPTR_FORMAT, p2i(callee.sp()));
log_develop_debug(continuations)("continuation_bottom_sender: [" JLONG_FORMAT "] [%d] callee: " INTPTR_FORMAT
" sender_sp: " INTPTR_FORMAT,
java_tid(thread), thread->osthread()->thread_id(), p2i(callee.sp()), p2i(sender_sp));
frame entry = ce->to_frame();
if (callee.is_interpreted_frame()) {
entry.set_sp(sender_sp); // sp != unextended_sp
}
return entry;
}
address Continuation::get_top_return_pc_post_barrier(JavaThread* thread, address pc) {
ContinuationEntry* ce;
if (thread != nullptr && is_return_barrier_entry(pc) && (ce = thread->last_continuation()) != nullptr) {
return ce->entry_pc();
}
return pc;
}
void Continuation::set_cont_fastpath_thread_state(JavaThread* thread) {
assert(thread != nullptr, "");
bool fast = !thread->is_interp_only_mode();
thread->set_cont_fastpath_thread_state(fast);
}
void Continuation::notify_deopt(JavaThread* thread, intptr_t* sp) {
ContinuationEntry* entry = thread->last_continuation();
if (entry == nullptr) {
return;
}
if (is_sp_in_continuation(entry, sp)) {
thread->push_cont_fastpath(sp);
return;
}
ContinuationEntry* prev;
do {
prev = entry;
entry = entry->parent();
} while (entry != nullptr && !is_sp_in_continuation(entry, sp));
if (entry == nullptr) {
return;
}
assert(is_sp_in_continuation(entry, sp), "");
if (sp > prev->parent_cont_fastpath()) {
prev->set_parent_cont_fastpath(sp);
}
}
#ifndef PRODUCT
void Continuation::describe(FrameValues &values) {
JavaThread* thread = JavaThread::active();
if (thread != nullptr) {
for (ContinuationEntry* ce = thread->last_continuation(); ce != nullptr; ce = ce->parent()) {
intptr_t* bottom = ce->entry_sp();
if (bottom != nullptr) {
values.describe(-1, bottom, "continuation entry");
}
}
}
}
#endif
#ifdef ASSERT
void Continuation::debug_verify_continuation(oop contOop) {
if (!VerifyContinuations) {
return;
}
assert(contOop != nullptr, "");
assert(oopDesc::is_oop(contOop), "");
ContinuationWrapper cont(contOop);
assert(oopDesc::is_oop_or_null(cont.tail()), "");
assert(cont.chunk_invariant(), "");
bool nonempty_chunk = false;
size_t max_size = 0;
int num_chunks = 0;
int num_frames = 0;
int num_interpreted_frames = 0;
int num_oops = 0;
for (stackChunkOop chunk = cont.tail(); chunk != nullptr; chunk = chunk->parent()) {
log_develop_trace(continuations)("debug_verify_continuation chunk %d", num_chunks);
chunk->verify(&max_size, &num_oops, &num_frames, &num_interpreted_frames);
if (!chunk->is_empty()) {
nonempty_chunk = true;
}
num_chunks++;
}
const bool is_empty = cont.is_empty();
assert(!nonempty_chunk || !is_empty, "");
assert(is_empty == (!nonempty_chunk && cont.last_frame().is_empty()), "");
}
void Continuation::print(oop continuation) { print_on(tty, continuation); }
void Continuation::print_on(outputStream* st, oop continuation) {
ContinuationWrapper cont(continuation);
st->print_cr("CONTINUATION: " PTR_FORMAT " done: %d",
continuation->identity_hash(), jdk_internal_vm_Continuation::done(continuation));
st->print_cr("CHUNKS:");
for (stackChunkOop chunk = cont.tail(); chunk != nullptr; chunk = chunk->parent()) {
st->print("* ");
chunk->print_on(true, st);
}
}
#endif // ASSERT
void continuations_init() { Continuations::init(); }
void Continuations::init() {
Continuation::init();
}
// While virtual threads are in Preview, there are some VM mechanisms we disable if continuations aren't used
bool Continuations::enabled() {
return VMContinuations && Arguments::enable_preview();
}
#define CC (char*) /*cast a literal from (const char*)*/
#define FN_PTR(f) CAST_FROM_FN_PTR(void*, &f)
static JNINativeMethod CONT_methods[] = {
{CC"pin", CC"()V", FN_PTR(CONT_pin)},
{CC"unpin", CC"()V", FN_PTR(CONT_unpin)},
{CC"isPinned0", CC"(Ljdk/internal/vm/ContinuationScope;)I", FN_PTR(CONT_isPinned0)},
};
void CONT_RegisterNativeMethods(JNIEnv *env, jclass cls) {
Thread* thread = Thread::current();
assert(thread->is_Java_thread(), "");
ThreadToNativeFromVM trans((JavaThread*)thread);
int status = env->RegisterNatives(cls, CONT_methods, sizeof(CONT_methods)/sizeof(JNINativeMethod));
guarantee(status == JNI_OK, "register jdk.internal.vm.Continuation natives");
guarantee(!env->ExceptionOccurred(), "register jdk.internal.vm.Continuation natives");
}
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