blob: d7477f1623f56b69f1afe65bdf60b288ece05f13 [file] [log] [blame]
// 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 "include/v8-internal.h"
#include "src/base/atomicops.h"
namespace v8 {
namespace internal {
class ExecutionAccess;
class InterruptsScope;
class Isolate;
class Object;
// StackGuard contains the handling of the limits that are used to limit the
// number of nested invocations of JavaScript and the stack size used in each
// invocation.
class V8_EXPORT_PRIVATE StackGuard final {
explicit StackGuard(Isolate* isolate) : isolate_(isolate) {}
// Pass the address beyond which the stack should not grow. The stack
// is assumed to grow downwards.
void SetStackLimit(uintptr_t limit);
// The simulator uses a separate JS stack. Limits on the JS stack might have
// to be adjusted in order to reflect overflows of the C stack, because we
// cannot rely on the interleaving of frames on the simulator.
void AdjustStackLimitForSimulator();
// Threading support.
char* ArchiveStackGuard(char* to);
char* RestoreStackGuard(char* from);
static int ArchiveSpacePerThread() { return sizeof(ThreadLocal); }
void FreeThreadResources();
// Sets up the default stack guard for this thread if it has not
// already been set up.
void InitThread(const ExecutionAccess& lock);
// Clears the stack guard for this thread so it does not look as if
// it has been set up.
void ClearThread(const ExecutionAccess& lock);
V(TERMINATE_EXECUTION, TerminateExecution, 0) \
V(INSTALL_CODE, InstallCode, 2) \
V(API_INTERRUPT, ApiInterrupt, 3) \
V(DEOPT_MARKED_ALLOCATION_SITES, DeoptMarkedAllocationSites, 4) \
V(GROW_SHARED_MEMORY, GrowSharedMemory, 5) \
V(LOG_WASM_CODE, LogWasmCode, 6) \
V(WASM_CODE_GC, WasmCodeGC, 7)
#define V(NAME, Name, id) \
inline bool Check##Name() { return CheckInterrupt(NAME); } \
inline void Request##Name() { RequestInterrupt(NAME); } \
inline void Clear##Name() { ClearInterrupt(NAME); }
#undef V
// Flag used to set the interrupt causes.
enum InterruptFlag {
#define V(NAME, Name, id) NAME = (1 << id),
#undef V
#define V(NAME, Name, id) NAME |
#undef V
uintptr_t climit() { return thread_local_.climit(); }
uintptr_t jslimit() { return thread_local_.jslimit(); }
// This provides an asynchronous read of the stack limits for the current
// thread. There are no locks protecting this, but it is assumed that you
// have the global V8 lock if you are using multiple V8 threads.
uintptr_t real_climit() { return thread_local_.real_climit_; }
uintptr_t real_jslimit() { return thread_local_.real_jslimit_; }
Address address_of_jslimit() {
return reinterpret_cast<Address>(&thread_local_.jslimit_);
Address address_of_real_jslimit() {
return reinterpret_cast<Address>(&thread_local_.real_jslimit_);
// If the stack guard is triggered, but it is not an actual
// stack overflow, then handle the interruption accordingly.
Object HandleInterrupts();
bool CheckInterrupt(InterruptFlag flag);
void RequestInterrupt(InterruptFlag flag);
void ClearInterrupt(InterruptFlag flag);
int FetchAndClearInterrupts();
// You should hold the ExecutionAccess lock when calling this method.
bool has_pending_interrupts(const ExecutionAccess& lock) {
return thread_local_.interrupt_flags_ != 0;
// You should hold the ExecutionAccess lock when calling this method.
inline void set_interrupt_limits(const ExecutionAccess& lock);
// Reset limits to actual values. For example after handling interrupt.
// You should hold the ExecutionAccess lock when calling this method.
inline void reset_limits(const ExecutionAccess& lock);
// Enable or disable interrupts.
void EnableInterrupts();
void DisableInterrupts();
static const uintptr_t kInterruptLimit = uintptr_t{0xfffffffffffffffe};
static const uintptr_t kIllegalLimit = uintptr_t{0xfffffffffffffff8};
static const uintptr_t kInterruptLimit = 0xfffffffe;
static const uintptr_t kIllegalLimit = 0xfffffff8;
void PushInterruptsScope(InterruptsScope* scope);
void PopInterruptsScope();
class ThreadLocal final {
ThreadLocal() { Clear(); }
// You should hold the ExecutionAccess lock when you call Initialize or
// Clear.
void Clear();
// Returns true if the heap's stack limits should be set, false if not.
bool Initialize(Isolate* isolate);
// The stack limit is split into a JavaScript and a C++ stack limit. These
// two are the same except when running on a simulator where the C++ and
// JavaScript stacks are separate. Each of the two stack limits have two
// values. The one eith the real_ prefix is the actual stack limit
// set for the VM. The one without the real_ prefix has the same value as
// the actual stack limit except when there is an interruption (e.g. debug
// break or preemption) in which case it is lowered to make stack checks
// fail. Both the generated code and the runtime system check against the
// one without the real_ prefix.
uintptr_t real_jslimit_; // Actual JavaScript stack limit set for the VM.
uintptr_t real_climit_; // Actual C++ stack limit set for the VM.
// jslimit_ and climit_ can be read without any lock.
// Writing requires the ExecutionAccess lock.
base::AtomicWord jslimit_;
base::AtomicWord climit_;
uintptr_t jslimit() {
return bit_cast<uintptr_t>(base::Relaxed_Load(&jslimit_));
void set_jslimit(uintptr_t limit) {
return base::Relaxed_Store(&jslimit_,
uintptr_t climit() {
return bit_cast<uintptr_t>(base::Relaxed_Load(&climit_));
void set_climit(uintptr_t limit) {
return base::Relaxed_Store(&climit_,
InterruptsScope* interrupt_scopes_;
int interrupt_flags_;
// TODO(isolates): Technically this could be calculated directly from a
// pointer to StackGuard.
Isolate* isolate_;
ThreadLocal thread_local_;
friend class Isolate;
friend class StackLimitCheck;
friend class InterruptsScope;
} // namespace internal
} // namespace v8