1 // Copyright 2014 the V8 project authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef V8_EXECUTION_H_ 6 #define V8_EXECUTION_H_ 7 8 #include "src/base/atomicops.h" 9 #include "src/globals.h" 10 11 namespace v8 { 12 namespace internal { 13 14 template <typename T> 15 class Handle; 16 17 class Execution final : public AllStatic { 18 public: 19 // Whether to report pending messages, or keep them pending on the isolate. 20 enum class MessageHandling { kReport, kKeepPending }; 21 enum class Target { kCallable, kRunMicrotasks }; 22 23 // Call a function, the caller supplies a receiver and an array 24 // of arguments. 25 // 26 // When the function called is not in strict mode, receiver is 27 // converted to an object. 28 // 29 V8_EXPORT_PRIVATE V8_WARN_UNUSED_RESULT static MaybeHandle<Object> Call( 30 Isolate* isolate, Handle<Object> callable, Handle<Object> receiver, 31 int argc, Handle<Object> argv[]); 32 33 // Construct object from function, the caller supplies an array of 34 // arguments. 35 V8_WARN_UNUSED_RESULT static MaybeHandle<Object> New( 36 Isolate* isolate, Handle<Object> constructor, int argc, 37 Handle<Object> argv[]); 38 V8_WARN_UNUSED_RESULT static MaybeHandle<Object> New( 39 Isolate* isolate, Handle<Object> constructor, Handle<Object> new_target, 40 int argc, Handle<Object> argv[]); 41 42 // Call a function, just like Call(), but handle don't report exceptions 43 // externally. 44 // The return value is either the result of calling the function (if no 45 // exception occurred), or an empty handle. 46 // If message_handling is MessageHandling::kReport, exceptions (except for 47 // termination exceptions) will be stored in exception_out (if not a 48 // nullptr). 49 static MaybeHandle<Object> TryCall(Isolate* isolate, Handle<Object> callable, 50 Handle<Object> receiver, int argc, 51 Handle<Object> argv[], 52 MessageHandling message_handling, 53 MaybeHandle<Object>* exception_out, 54 Target target = Target::kCallable); 55 // Convenience method for performing RunMicrotasks 56 static MaybeHandle<Object> RunMicrotasks(Isolate* isolate, 57 MessageHandling message_handling, 58 MaybeHandle<Object>* exception_out); 59 }; 60 61 62 class ExecutionAccess; 63 class InterruptsScope; 64 65 // StackGuard contains the handling of the limits that are used to limit the 66 // number of nested invocations of JavaScript and the stack size used in each 67 // invocation. 68 class V8_EXPORT_PRIVATE StackGuard final { 69 public: 70 // Pass the address beyond which the stack should not grow. The stack 71 // is assumed to grow downwards. 72 void SetStackLimit(uintptr_t limit); 73 74 // The simulator uses a separate JS stack. Limits on the JS stack might have 75 // to be adjusted in order to reflect overflows of the C stack, because we 76 // cannot rely on the interleaving of frames on the simulator. 77 void AdjustStackLimitForSimulator(); 78 79 // Threading support. 80 char* ArchiveStackGuard(char* to); 81 char* RestoreStackGuard(char* from); ArchiveSpacePerThread()82 static int ArchiveSpacePerThread() { return sizeof(ThreadLocal); } 83 void FreeThreadResources(); 84 // Sets up the default stack guard for this thread if it has not 85 // already been set up. 86 void InitThread(const ExecutionAccess& lock); 87 // Clears the stack guard for this thread so it does not look as if 88 // it has been set up. 89 void ClearThread(const ExecutionAccess& lock); 90 91 #define INTERRUPT_LIST(V) \ 92 V(DEBUGBREAK, DebugBreak, 0) \ 93 V(TERMINATE_EXECUTION, TerminateExecution, 1) \ 94 V(GC_REQUEST, GC, 2) \ 95 V(INSTALL_CODE, InstallCode, 3) \ 96 V(API_INTERRUPT, ApiInterrupt, 4) \ 97 V(DEOPT_MARKED_ALLOCATION_SITES, DeoptMarkedAllocationSites, 5) 98 99 #define V(NAME, Name, id) \ 100 inline bool Check##Name() { return CheckInterrupt(NAME); } \ 101 inline bool CheckAndClear##Name() { return CheckAndClearInterrupt(NAME); } \ 102 inline void Request##Name() { RequestInterrupt(NAME); } \ 103 inline void Clear##Name() { ClearInterrupt(NAME); } 104 INTERRUPT_LIST(V) 105 #undef V 106 107 // Flag used to set the interrupt causes. 108 enum InterruptFlag { 109 #define V(NAME, Name, id) NAME = (1 << id), 110 INTERRUPT_LIST(V) 111 #undef V 112 #define V(NAME, Name, id) NAME | 113 ALL_INTERRUPTS = INTERRUPT_LIST(V) 0 114 #undef V 115 }; 116 climit()117 uintptr_t climit() { return thread_local_.climit(); } jslimit()118 uintptr_t jslimit() { return thread_local_.jslimit(); } 119 // This provides an asynchronous read of the stack limits for the current 120 // thread. There are no locks protecting this, but it is assumed that you 121 // have the global V8 lock if you are using multiple V8 threads. real_climit()122 uintptr_t real_climit() { 123 return thread_local_.real_climit_; 124 } real_jslimit()125 uintptr_t real_jslimit() { 126 return thread_local_.real_jslimit_; 127 } address_of_jslimit()128 Address address_of_jslimit() { 129 return reinterpret_cast<Address>(&thread_local_.jslimit_); 130 } address_of_real_jslimit()131 Address address_of_real_jslimit() { 132 return reinterpret_cast<Address>(&thread_local_.real_jslimit_); 133 } 134 135 // If the stack guard is triggered, but it is not an actual 136 // stack overflow, then handle the interruption accordingly. 137 Object* HandleInterrupts(); 138 139 private: 140 StackGuard(); 141 142 bool CheckInterrupt(InterruptFlag flag); 143 void RequestInterrupt(InterruptFlag flag); 144 void ClearInterrupt(InterruptFlag flag); 145 bool CheckAndClearInterrupt(InterruptFlag flag); 146 147 // You should hold the ExecutionAccess lock when calling this method. has_pending_interrupts(const ExecutionAccess & lock)148 bool has_pending_interrupts(const ExecutionAccess& lock) { 149 return thread_local_.interrupt_flags_ != 0; 150 } 151 152 // You should hold the ExecutionAccess lock when calling this method. 153 inline void set_interrupt_limits(const ExecutionAccess& lock); 154 155 // Reset limits to actual values. For example after handling interrupt. 156 // You should hold the ExecutionAccess lock when calling this method. 157 inline void reset_limits(const ExecutionAccess& lock); 158 159 // Enable or disable interrupts. 160 void EnableInterrupts(); 161 void DisableInterrupts(); 162 163 #if V8_TARGET_ARCH_64_BIT 164 static const uintptr_t kInterruptLimit = uintptr_t{0xfffffffffffffffe}; 165 static const uintptr_t kIllegalLimit = uintptr_t{0xfffffffffffffff8}; 166 #else 167 static const uintptr_t kInterruptLimit = 0xfffffffe; 168 static const uintptr_t kIllegalLimit = 0xfffffff8; 169 #endif 170 171 void PushInterruptsScope(InterruptsScope* scope); 172 void PopInterruptsScope(); 173 174 class ThreadLocal final { 175 public: ThreadLocal()176 ThreadLocal() { Clear(); } 177 // You should hold the ExecutionAccess lock when you call Initialize or 178 // Clear. 179 void Clear(); 180 181 // Returns true if the heap's stack limits should be set, false if not. 182 bool Initialize(Isolate* isolate); 183 184 // The stack limit is split into a JavaScript and a C++ stack limit. These 185 // two are the same except when running on a simulator where the C++ and 186 // JavaScript stacks are separate. Each of the two stack limits have two 187 // values. The one eith the real_ prefix is the actual stack limit 188 // set for the VM. The one without the real_ prefix has the same value as 189 // the actual stack limit except when there is an interruption (e.g. debug 190 // break or preemption) in which case it is lowered to make stack checks 191 // fail. Both the generated code and the runtime system check against the 192 // one without the real_ prefix. 193 uintptr_t real_jslimit_; // Actual JavaScript stack limit set for the VM. 194 uintptr_t real_climit_; // Actual C++ stack limit set for the VM. 195 196 // jslimit_ and climit_ can be read without any lock. 197 // Writing requires the ExecutionAccess lock. 198 base::AtomicWord jslimit_; 199 base::AtomicWord climit_; 200 jslimit()201 uintptr_t jslimit() { 202 return bit_cast<uintptr_t>(base::Relaxed_Load(&jslimit_)); 203 } set_jslimit(uintptr_t limit)204 void set_jslimit(uintptr_t limit) { 205 return base::Relaxed_Store(&jslimit_, 206 static_cast<base::AtomicWord>(limit)); 207 } climit()208 uintptr_t climit() { 209 return bit_cast<uintptr_t>(base::Relaxed_Load(&climit_)); 210 } set_climit(uintptr_t limit)211 void set_climit(uintptr_t limit) { 212 return base::Relaxed_Store(&climit_, 213 static_cast<base::AtomicWord>(limit)); 214 } 215 216 InterruptsScope* interrupt_scopes_; 217 int interrupt_flags_; 218 }; 219 220 // TODO(isolates): Technically this could be calculated directly from a 221 // pointer to StackGuard. 222 Isolate* isolate_; 223 ThreadLocal thread_local_; 224 225 friend class Isolate; 226 friend class StackLimitCheck; 227 friend class InterruptsScope; 228 229 DISALLOW_COPY_AND_ASSIGN(StackGuard); 230 }; 231 232 } // namespace internal 233 } // namespace v8 234 235 #endif // V8_EXECUTION_H_ 236