1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
|
// 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.
#ifndef V8_EXECUTION_STACK_GUARD_H_
#define V8_EXECUTION_STACK_GUARD_H_
#include "include/v8-internal.h"
#include "src/base/atomicops.h"
#include "src/common/globals.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 {
public:
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.
void InitThread(const ExecutionAccess& lock);
#define INTERRUPT_LIST(V) \
V(TERMINATE_EXECUTION, TerminateExecution, 0) \
V(GC_REQUEST, GC, 1) \
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); }
INTERRUPT_LIST(V)
#undef V
// Flag used to set the interrupt causes.
enum InterruptFlag {
#define V(NAME, Name, id) NAME = (1 << id),
INTERRUPT_LIST(V)
#undef V
#define V(NAME, Name, id) NAME |
ALL_INTERRUPTS = INTERRUPT_LIST(V) 0
#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();
static constexpr int kSizeInBytes = 7 * kSystemPointerSize;
private:
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();
#if V8_TARGET_ARCH_64_BIT
static const uintptr_t kInterruptLimit = uintptr_t{0xfffffffffffffffe};
static const uintptr_t kIllegalLimit = uintptr_t{0xfffffffffffffff8};
#else
static const uintptr_t kInterruptLimit = 0xfffffffe;
static const uintptr_t kIllegalLimit = 0xfffffff8;
#endif
void PushInterruptsScope(InterruptsScope* scope);
void PopInterruptsScope();
class ThreadLocal final {
public:
ThreadLocal() {}
void Initialize(Isolate* isolate, const ExecutionAccess& lock);
// 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.
// Actual JavaScript stack limit set for the VM.
uintptr_t real_jslimit_ = kIllegalLimit;
// Actual C++ stack limit set for the VM.
uintptr_t real_climit_ = kIllegalLimit;
// jslimit_ and climit_ can be read without any lock.
// Writing requires the ExecutionAccess lock.
base::AtomicWord jslimit_ = kIllegalLimit;
base::AtomicWord climit_ = kIllegalLimit;
uintptr_t jslimit() {
return bit_cast<uintptr_t>(base::Relaxed_Load(&jslimit_));
}
void set_jslimit(uintptr_t limit) {
return base::Relaxed_Store(&jslimit_,
static_cast<base::AtomicWord>(limit));
}
uintptr_t climit() {
return bit_cast<uintptr_t>(base::Relaxed_Load(&climit_));
}
void set_climit(uintptr_t limit) {
return base::Relaxed_Store(&climit_,
static_cast<base::AtomicWord>(limit));
}
InterruptsScope* interrupt_scopes_ = nullptr;
intptr_t interrupt_flags_ = 0;
};
// 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;
DISALLOW_COPY_AND_ASSIGN(StackGuard);
};
STATIC_ASSERT(StackGuard::kSizeInBytes == sizeof(StackGuard));
} // namespace internal
} // namespace v8
#endif // V8_EXECUTION_STACK_GUARD_H_
|
