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// Copyright 2019 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/execution/stack-guard.h"
#include "src/base/atomicops.h"
#include "src/compiler-dispatcher/optimizing-compile-dispatcher.h"
#include "src/execution/interrupts-scope.h"
#include "src/execution/isolate.h"
#include "src/execution/protectors-inl.h"
#include "src/execution/simulator.h"
#include "src/logging/counters.h"
#include "src/objects/backing-store.h"
#include "src/roots/roots-inl.h"
#include "src/tracing/trace-event.h"
#include "src/utils/memcopy.h"
#ifdef V8_ENABLE_SPARKPLUG
#include "src/baseline/baseline-batch-compiler.h"
#endif
#ifdef V8_ENABLE_MAGLEV
#include "src/maglev/maglev-concurrent-dispatcher.h"
#endif // V8_ENABLE_MAGLEV
#if V8_ENABLE_WEBASSEMBLY
#include "src/wasm/wasm-engine.h"
#endif // V8_ENABLE_WEBASSEMBLY
namespace v8 {
namespace internal {
void StackGuard::update_interrupt_requests_and_stack_limits(
const ExecutionAccess& lock) {
DCHECK_NOT_NULL(isolate_);
if (has_pending_interrupts(lock)) {
thread_local_.set_jslimit(kInterruptLimit);
#ifdef USE_SIMULATOR
thread_local_.set_climit(kInterruptLimit);
#endif
} else {
thread_local_.set_jslimit(thread_local_.real_jslimit_);
#ifdef USE_SIMULATOR
thread_local_.set_climit(thread_local_.real_climit_);
#endif
}
for (InterruptLevel level :
std::array{InterruptLevel::kNoGC, InterruptLevel::kNoHeapWrites,
InterruptLevel::kAnyEffect}) {
thread_local_.set_interrupt_requested(
level, InterruptLevelMask(level) & thread_local_.interrupt_flags_);
}
}
void StackGuard::SetStackLimit(uintptr_t limit) {
ExecutionAccess access(isolate_);
SetStackLimitInternal(access, limit,
SimulatorStack::JsLimitFromCLimit(isolate_, limit));
}
void StackGuard::SetStackLimitInternal(const ExecutionAccess& lock,
uintptr_t limit, uintptr_t jslimit) {
// If the current limits are special (e.g. due to a pending interrupt) then
// leave them alone.
if (thread_local_.jslimit() == thread_local_.real_jslimit_) {
thread_local_.set_jslimit(jslimit);
}
thread_local_.real_jslimit_ = jslimit;
#ifdef USE_SIMULATOR
if (thread_local_.climit() == thread_local_.real_climit_) {
thread_local_.set_climit(limit);
}
thread_local_.real_climit_ = limit;
#endif
}
void StackGuard::SetStackLimitForStackSwitching(uintptr_t limit) {
// Try to compare and swap the new jslimit without the ExecutionAccess lock.
uintptr_t old_jslimit = base::Relaxed_CompareAndSwap(
&thread_local_.jslimit_, thread_local_.real_jslimit_, limit);
USE(old_jslimit);
DCHECK_IMPLIES(old_jslimit != thread_local_.real_jslimit_,
old_jslimit == kInterruptLimit);
// Either way, set the real limit. This does not require synchronization.
thread_local_.real_jslimit_ = limit;
}
#ifdef USE_SIMULATOR
void StackGuard::AdjustStackLimitForSimulator() {
ExecutionAccess access(isolate_);
uintptr_t climit = thread_local_.real_climit_;
// If the current limits are special (e.g. due to a pending interrupt) then
// leave them alone.
uintptr_t jslimit = SimulatorStack::JsLimitFromCLimit(isolate_, climit);
if (thread_local_.jslimit() == thread_local_.real_jslimit_) {
thread_local_.set_jslimit(jslimit);
}
}
void StackGuard::ResetStackLimitForSimulator() {
ExecutionAccess access(isolate_);
// If the current limits are special due to a pending interrupt then
// leave them alone.
if (thread_local_.jslimit() != kInterruptLimit) {
thread_local_.set_jslimit(thread_local_.real_jslimit_);
}
}
#endif
void StackGuard::PushInterruptsScope(InterruptsScope* scope) {
ExecutionAccess access(isolate_);
DCHECK_NE(scope->mode_, InterruptsScope::kNoop);
if (scope->mode_ == InterruptsScope::kPostponeInterrupts) {
// Intercept already requested interrupts.
uint32_t intercepted =
thread_local_.interrupt_flags_ & scope->intercept_mask_;
scope->intercepted_flags_ = intercepted;
thread_local_.interrupt_flags_ &= ~intercepted;
} else {
DCHECK_EQ(scope->mode_, InterruptsScope::kRunInterrupts);
// Restore postponed interrupts.
uint32_t restored_flags = 0;
for (InterruptsScope* current = thread_local_.interrupt_scopes_;
current != nullptr; current = current->prev_) {
restored_flags |= (current->intercepted_flags_ & scope->intercept_mask_);
current->intercepted_flags_ &= ~scope->intercept_mask_;
}
thread_local_.interrupt_flags_ |= restored_flags;
}
update_interrupt_requests_and_stack_limits(access);
// Add scope to the chain.
scope->prev_ = thread_local_.interrupt_scopes_;
thread_local_.interrupt_scopes_ = scope;
}
void StackGuard::PopInterruptsScope() {
ExecutionAccess access(isolate_);
InterruptsScope* top = thread_local_.interrupt_scopes_;
DCHECK_NE(top->mode_, InterruptsScope::kNoop);
if (top->mode_ == InterruptsScope::kPostponeInterrupts) {
// Make intercepted interrupts active.
DCHECK_EQ(thread_local_.interrupt_flags_ & top->intercept_mask_, 0);
thread_local_.interrupt_flags_ |= top->intercepted_flags_;
} else {
DCHECK_EQ(top->mode_, InterruptsScope::kRunInterrupts);
// Postpone existing interupts if needed.
if (top->prev_) {
for (uint32_t interrupt = 1; interrupt < ALL_INTERRUPTS;
interrupt = interrupt << 1) {
InterruptFlag flag = static_cast<InterruptFlag>(interrupt);
if ((thread_local_.interrupt_flags_ & flag) &&
top->prev_->Intercept(flag)) {
thread_local_.interrupt_flags_ &= ~flag;
}
}
}
}
update_interrupt_requests_and_stack_limits(access);
// Remove scope from chain.
thread_local_.interrupt_scopes_ = top->prev_;
}
bool StackGuard::CheckInterrupt(InterruptFlag flag) {
ExecutionAccess access(isolate_);
return (thread_local_.interrupt_flags_ & flag) != 0;
}
void StackGuard::RequestInterrupt(InterruptFlag flag) {
ExecutionAccess access(isolate_);
// Check the chain of InterruptsScope for interception.
if (thread_local_.interrupt_scopes_ &&
thread_local_.interrupt_scopes_->Intercept(flag)) {
return;
}
// Not intercepted. Set as active interrupt flag.
thread_local_.interrupt_flags_ |= flag;
update_interrupt_requests_and_stack_limits(access);
// If this isolate is waiting in a futex, notify it to wake up.
isolate_->futex_wait_list_node()->NotifyWake();
}
void StackGuard::ClearInterrupt(InterruptFlag flag) {
ExecutionAccess access(isolate_);
// Clear the interrupt flag from the chain of InterruptsScope.
for (InterruptsScope* current = thread_local_.interrupt_scopes_;
current != nullptr; current = current->prev_) {
current->intercepted_flags_ &= ~flag;
}
// Clear the interrupt flag from the active interrupt flags.
thread_local_.interrupt_flags_ &= ~flag;
update_interrupt_requests_and_stack_limits(access);
}
bool StackGuard::HasTerminationRequest() {
if (!thread_local_.has_interrupt_requested(InterruptLevel::kNoGC)) {
return false;
}
ExecutionAccess access(isolate_);
if ((thread_local_.interrupt_flags_ & TERMINATE_EXECUTION) != 0) {
thread_local_.interrupt_flags_ &= ~TERMINATE_EXECUTION;
update_interrupt_requests_and_stack_limits(access);
return true;
}
return false;
}
int StackGuard::FetchAndClearInterrupts(InterruptLevel level) {
ExecutionAccess access(isolate_);
InterruptFlag mask = InterruptLevelMask(level);
if ((thread_local_.interrupt_flags_ & TERMINATE_EXECUTION) != 0) {
// The TERMINATE_EXECUTION interrupt is special, since it terminates
// execution but should leave V8 in a resumable state. If it exists, we only
// fetch and clear that bit. On resume, V8 can continue processing other
// interrupts.
mask = TERMINATE_EXECUTION;
}
int result = static_cast<int>(thread_local_.interrupt_flags_ & mask);
thread_local_.interrupt_flags_ &= ~mask;
update_interrupt_requests_and_stack_limits(access);
return result;
}
char* StackGuard::ArchiveStackGuard(char* to) {
ExecutionAccess access(isolate_);
MemCopy(to, reinterpret_cast<char*>(&thread_local_), sizeof(ThreadLocal));
thread_local_ = {};
return to + sizeof(ThreadLocal);
}
char* StackGuard::RestoreStackGuard(char* from) {
ExecutionAccess access(isolate_);
MemCopy(reinterpret_cast<char*>(&thread_local_), from, sizeof(ThreadLocal));
return from + sizeof(ThreadLocal);
}
void StackGuard::FreeThreadResources() {
Isolate::PerIsolateThreadData* per_thread =
isolate_->FindOrAllocatePerThreadDataForThisThread();
per_thread->set_stack_limit(real_climit());
}
void StackGuard::ThreadLocal::Initialize(Isolate* isolate,
const ExecutionAccess& lock) {
const uintptr_t kLimitSize = v8_flags.stack_size * KB;
DCHECK_GT(base::Stack::GetStackStart(), kLimitSize);
uintptr_t limit = base::Stack::GetStackStart() - kLimitSize;
real_jslimit_ = SimulatorStack::JsLimitFromCLimit(isolate, limit);
set_jslimit(SimulatorStack::JsLimitFromCLimit(isolate, limit));
#ifdef USE_SIMULATOR
real_climit_ = limit;
set_climit(limit);
#endif
interrupt_scopes_ = nullptr;
interrupt_flags_ = 0;
}
void StackGuard::InitThread(const ExecutionAccess& lock) {
thread_local_.Initialize(isolate_, lock);
Isolate::PerIsolateThreadData* per_thread =
isolate_->FindOrAllocatePerThreadDataForThisThread();
uintptr_t stored_limit = per_thread->stack_limit();
// You should hold the ExecutionAccess lock when you call this.
if (stored_limit != 0) {
SetStackLimit(stored_limit);
}
}
// --- C a l l s t o n a t i v e s ---
namespace {
bool TestAndClear(int* bitfield, int mask) {
bool result = (*bitfield & mask);
*bitfield &= ~mask;
return result;
}
class V8_NODISCARD ShouldBeZeroOnReturnScope final {
public:
#ifndef DEBUG
explicit ShouldBeZeroOnReturnScope(int*) {}
#else // DEBUG
explicit ShouldBeZeroOnReturnScope(int* v) : v_(v) {}
~ShouldBeZeroOnReturnScope() { DCHECK_EQ(*v_, 0); }
private:
int* v_;
#endif // DEBUG
};
} // namespace
Tagged<Object> StackGuard::HandleInterrupts(InterruptLevel level) {
TRACE_EVENT0("v8.execute", "V8.HandleInterrupts");
#if DEBUG
isolate_->heap()->VerifyNewSpaceTop();
#endif
if (v8_flags.verify_predictable) {
// Advance synthetic time by making a time request.
isolate_->heap()->MonotonicallyIncreasingTimeInMs();
}
// Fetch and clear interrupt bits in one go. See comments inside the method
// for special handling of TERMINATE_EXECUTION.
int interrupt_flags = FetchAndClearInterrupts(level);
// All interrupts should be fully processed when returning from this method.
ShouldBeZeroOnReturnScope should_be_zero_on_return(&interrupt_flags);
if (TestAndClear(&interrupt_flags, TERMINATE_EXECUTION)) {
TRACE_EVENT0("v8.execute", "V8.TerminateExecution");
return isolate_->TerminateExecution();
}
if (TestAndClear(&interrupt_flags, GC_REQUEST)) {
TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.gc"), "V8.GCHandleGCRequest");
isolate_->heap()->HandleGCRequest();
}
if (TestAndClear(&interrupt_flags, START_INCREMENTAL_MARKING)) {
isolate_->heap()->StartIncrementalMarkingOnInterrupt();
}
if (TestAndClear(&interrupt_flags, GLOBAL_SAFEPOINT)) {
TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.gc"), "V8.GlobalSafepoint");
isolate_->main_thread_local_heap()->Safepoint();
}
#if V8_ENABLE_WEBASSEMBLY
if (TestAndClear(&interrupt_flags, GROW_SHARED_MEMORY)) {
TRACE_EVENT0("v8.wasm", "V8.WasmGrowSharedMemory");
BackingStore::UpdateSharedWasmMemoryObjects(isolate_);
}
if (TestAndClear(&interrupt_flags, LOG_WASM_CODE)) {
TRACE_EVENT0("v8.wasm", "V8.LogCode");
wasm::GetWasmEngine()->LogOutstandingCodesForIsolate(isolate_);
}
if (TestAndClear(&interrupt_flags, WASM_CODE_GC)) {
TRACE_EVENT0("v8.wasm", "V8.WasmCodeGC");
wasm::GetWasmEngine()->ReportLiveCodeFromStackForGC(isolate_);
}
#endif // V8_ENABLE_WEBASSEMBLY
if (TestAndClear(&interrupt_flags, DEOPT_MARKED_ALLOCATION_SITES)) {
TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.gc"),
"V8.GCDeoptMarkedAllocationSites");
isolate_->heap()->DeoptMarkedAllocationSites();
}
if (TestAndClear(&interrupt_flags, INSTALL_CODE)) {
TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
"V8.InstallOptimizedFunctions");
DCHECK(isolate_->concurrent_recompilation_enabled());
isolate_->optimizing_compile_dispatcher()->InstallOptimizedFunctions();
}
#ifdef V8_ENABLE_SPARKPLUG
if (TestAndClear(&interrupt_flags, INSTALL_BASELINE_CODE)) {
TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
"V8.FinalizeBaselineConcurrentCompilation");
isolate_->baseline_batch_compiler()->InstallBatch();
}
#endif // V8_ENABLE_SPARKPLUG
#ifdef V8_ENABLE_MAGLEV
if (TestAndClear(&interrupt_flags, INSTALL_MAGLEV_CODE)) {
TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
"V8.FinalizeMaglevConcurrentCompilation");
isolate_->maglev_concurrent_dispatcher()->FinalizeFinishedJobs();
}
#endif // V8_ENABLE_MAGLEV
if (TestAndClear(&interrupt_flags, API_INTERRUPT)) {
TRACE_EVENT0("v8.execute", "V8.InvokeApiInterruptCallbacks");
// Callbacks must be invoked outside of ExecutionAccess lock.
isolate_->InvokeApiInterruptCallbacks();
}
#ifdef V8_RUNTIME_CALL_STATS
// Runtime call stats can be enabled at any via Chrome tracing and since
// there's no global list of active Isolates this seems to be the only
// simple way to invalidate the protector.
if (TracingFlags::is_runtime_stats_enabled() &&
Protectors::IsNoProfilingIntact(isolate_)) {
Protectors::InvalidateNoProfiling(isolate_);
}
#endif
isolate_->counters()->stack_interrupts()->Increment();
return ReadOnlyRoots(isolate_).undefined_value();
}
} // namespace internal
} // namespace v8