1/*
2 * Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
3 * Copyright (C) 2001 Peter Kelly (pmk@post.com)
4 * Copyright (C) 2003-2018 Apple Inc. All rights reserved.
5 *
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Library General Public
8 * License as published by the Free Software Foundation; either
9 * version 2 of the License, or (at your option) any later version.
10 *
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Library General Public License for more details.
15 *
16 * You should have received a copy of the GNU Library General Public License
17 * along with this library; see the file COPYING.LIB. If not, write to
18 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
19 * Boston, MA 02110-1301, USA.
20 *
21 */
22
23#pragma once
24
25#include "AbstractPC.h"
26#include "CalleeBits.h"
27#include "MacroAssemblerCodeRef.h"
28#include "Register.h"
29#include "StackVisitor.h"
30#include "VM.h"
31#include "VMEntryRecord.h"
32
33namespace JSC {
34
35 class Arguments;
36 class ExecState;
37 class Interpreter;
38 class JSCallee;
39 class JSScope;
40 class SourceOrigin;
41
42 struct Instruction;
43
44 typedef ExecState CallFrame;
45
46 class CallSiteIndex {
47 public:
48 CallSiteIndex() = default;
49
50 explicit CallSiteIndex(uint32_t bits)
51 : m_bits(bits)
52 { }
53#if USE(JSVALUE32_64)
54 explicit CallSiteIndex(const Instruction* instruction)
55 : m_bits(bitwise_cast<uint32_t>(instruction))
56 { }
57#endif
58
59 explicit operator bool() const { return m_bits != UINT_MAX; }
60 bool operator==(const CallSiteIndex& other) const { return m_bits == other.m_bits; }
61
62 inline uint32_t bits() const { return m_bits; }
63
64 private:
65 uint32_t m_bits { UINT_MAX };
66 };
67
68 class DisposableCallSiteIndex : public CallSiteIndex {
69 public:
70 DisposableCallSiteIndex() = default;
71
72 explicit DisposableCallSiteIndex(uint32_t bits)
73 : CallSiteIndex(bits)
74 {
75 }
76
77 static DisposableCallSiteIndex fromCallSiteIndex(CallSiteIndex callSiteIndex)
78 {
79 return DisposableCallSiteIndex(callSiteIndex.bits());
80 }
81 };
82
83 // arm64_32 expects caller frame and return pc to use 8 bytes
84 struct CallerFrameAndPC {
85 alignas(CPURegister) CallFrame* callerFrame;
86 alignas(CPURegister) const Instruction* returnPC;
87 static const int sizeInRegisters = 2 * sizeof(CPURegister) / sizeof(Register);
88 };
89 static_assert(CallerFrameAndPC::sizeInRegisters == sizeof(CallerFrameAndPC) / sizeof(Register), "CallerFrameAndPC::sizeInRegisters is incorrect.");
90
91 struct CallFrameSlot {
92 static const int codeBlock = CallerFrameAndPC::sizeInRegisters;
93 static const int callee = codeBlock + 1;
94 static const int argumentCount = callee + 1;
95 static const int thisArgument = argumentCount + 1;
96 static const int firstArgument = thisArgument + 1;
97 };
98
99 // Represents the current state of script execution.
100 // Passed as the first argument to most functions.
101 class ExecState : private Register {
102 public:
103 static const int headerSizeInRegisters = CallFrameSlot::argumentCount + 1;
104
105 // This function should only be called in very specific circumstances
106 // when you've guaranteed the callee can't be a Wasm callee, and can
107 // be an arbitrary JSValue. This function should basically never be used.
108 // Its only use right now is when we are making a call, and we're not
109 // yet sure if the callee is a cell. In general, a JS callee is guaranteed
110 // to be a cell, however, there is a brief window where we need to check
111 // to see if it's a cell, and if it's not, we throw an exception.
112 JSValue guaranteedJSValueCallee() const
113 {
114 ASSERT(!callee().isWasm());
115 return this[CallFrameSlot::callee].jsValue();
116 }
117 JSObject* jsCallee() const
118 {
119 ASSERT(!callee().isWasm());
120 return this[CallFrameSlot::callee].object();
121 }
122 CalleeBits callee() const { return CalleeBits(this[CallFrameSlot::callee].pointer()); }
123 SUPPRESS_ASAN CalleeBits unsafeCallee() const { return CalleeBits(this[CallFrameSlot::callee].asanUnsafePointer()); }
124 CodeBlock* codeBlock() const { return this[CallFrameSlot::codeBlock].Register::codeBlock(); }
125 CodeBlock** addressOfCodeBlock() const { return bitwise_cast<CodeBlock**>(this + CallFrameSlot::codeBlock); }
126 SUPPRESS_ASAN CodeBlock* unsafeCodeBlock() const { return this[CallFrameSlot::codeBlock].Register::asanUnsafeCodeBlock(); }
127 JSScope* scope(int scopeRegisterOffset) const
128 {
129 ASSERT(this[scopeRegisterOffset].Register::scope());
130 return this[scopeRegisterOffset].Register::scope();
131 }
132
133 JSGlobalObject* wasmAwareLexicalGlobalObject(VM&);
134
135 bool isAnyWasmCallee();
136
137 // Global object in which the currently executing code was defined.
138 // Differs from VM::vmEntryGlobalObject() during function calls across web browser frames.
139 JSGlobalObject* lexicalGlobalObject() const;
140
141 // Differs from lexicalGlobalObject because this will have DOM window shell rather than
142 // the actual DOM window, which can't be "this" for security reasons.
143 JSObject* globalThisValue() const;
144
145 VM& vm() const;
146
147 static CallFrame* create(Register* callFrameBase) { return static_cast<CallFrame*>(callFrameBase); }
148 Register* registers() { return this; }
149 const Register* registers() const { return this; }
150
151 CallFrame& operator=(const Register& r) { *static_cast<Register*>(this) = r; return *this; }
152
153 CallFrame* callerFrame() const { return static_cast<CallFrame*>(callerFrameOrEntryFrame()); }
154 void* callerFrameOrEntryFrame() const { return callerFrameAndPC().callerFrame; }
155 SUPPRESS_ASAN void* unsafeCallerFrameOrEntryFrame() const { return unsafeCallerFrameAndPC().callerFrame; }
156
157 CallFrame* unsafeCallerFrame(EntryFrame*&) const;
158 JS_EXPORT_PRIVATE CallFrame* callerFrame(EntryFrame*&) const;
159
160 JS_EXPORT_PRIVATE SourceOrigin callerSourceOrigin();
161
162 static ptrdiff_t callerFrameOffset() { return OBJECT_OFFSETOF(CallerFrameAndPC, callerFrame); }
163
164 ReturnAddressPtr returnPC() const { return ReturnAddressPtr(callerFrameAndPC().returnPC); }
165 bool hasReturnPC() const { return !!callerFrameAndPC().returnPC; }
166 void clearReturnPC() { callerFrameAndPC().returnPC = 0; }
167 static ptrdiff_t returnPCOffset() { return OBJECT_OFFSETOF(CallerFrameAndPC, returnPC); }
168 AbstractPC abstractReturnPC(VM& vm) { return AbstractPC(vm, this); }
169
170 bool callSiteBitsAreBytecodeOffset() const;
171 bool callSiteBitsAreCodeOriginIndex() const;
172
173 unsigned callSiteAsRawBits() const;
174 unsigned unsafeCallSiteAsRawBits() const;
175 CallSiteIndex callSiteIndex() const;
176 CallSiteIndex unsafeCallSiteIndex() const;
177 private:
178 unsigned callSiteBitsAsBytecodeOffset() const;
179 public:
180
181 // This will try to get you the bytecode offset, but you should be aware that
182 // this bytecode offset may be bogus in the presence of inlining. This will
183 // also return 0 if the call frame has no notion of bytecode offsets (for
184 // example if it's native code).
185 // https://bugs.webkit.org/show_bug.cgi?id=121754
186 unsigned bytecodeOffset();
187
188 // This will get you a CodeOrigin. It will always succeed. May return
189 // CodeOrigin(0) if we're in native code.
190 JS_EXPORT_PRIVATE CodeOrigin codeOrigin();
191
192 Register* topOfFrame()
193 {
194 if (!codeBlock())
195 return registers();
196 return topOfFrameInternal();
197 }
198
199 const Instruction* currentVPC() const; // This only makes sense in the LLInt and baseline.
200 void setCurrentVPC(const Instruction*);
201
202 void setCallerFrame(CallFrame* frame) { callerFrameAndPC().callerFrame = frame; }
203 void setScope(int scopeRegisterOffset, JSScope* scope) { static_cast<Register*>(this)[scopeRegisterOffset] = scope; }
204
205 static void initGlobalExec(ExecState* globalExec, JSCallee* globalCallee);
206
207 // Read a register from the codeframe (or constant from the CodeBlock).
208 Register& r(int);
209 Register& r(VirtualRegister);
210 // Read a register for a non-constant
211 Register& uncheckedR(int);
212 Register& uncheckedR(VirtualRegister);
213
214 // Access to arguments as passed. (After capture, arguments may move to a different location.)
215 size_t argumentCount() const { return argumentCountIncludingThis() - 1; }
216 size_t argumentCountIncludingThis() const { return this[CallFrameSlot::argumentCount].payload(); }
217 static int argumentOffset(int argument) { return (CallFrameSlot::firstArgument + argument); }
218 static int argumentOffsetIncludingThis(int argument) { return (CallFrameSlot::thisArgument + argument); }
219
220 // In the following (argument() and setArgument()), the 'argument'
221 // parameter is the index of the arguments of the target function of
222 // this frame. The index starts at 0 for the first arg, 1 for the
223 // second, etc.
224 //
225 // The arguments (in this case) do not include the 'this' value.
226 // arguments(0) will not fetch the 'this' value. To get/set 'this',
227 // use thisValue() and setThisValue() below.
228
229 JSValue* addressOfArgumentsStart() const { return bitwise_cast<JSValue*>(this + argumentOffset(0)); }
230 JSValue argument(size_t argument)
231 {
232 if (argument >= argumentCount())
233 return jsUndefined();
234 return getArgumentUnsafe(argument);
235 }
236 JSValue uncheckedArgument(size_t argument)
237 {
238 ASSERT(argument < argumentCount());
239 return getArgumentUnsafe(argument);
240 }
241 void setArgument(size_t argument, JSValue value)
242 {
243 this[argumentOffset(argument)] = value;
244 }
245
246 JSValue getArgumentUnsafe(size_t argIndex)
247 {
248 // User beware! This method does not verify that there is a valid
249 // argument at the specified argIndex. This is used for debugging
250 // and verification code only. The caller is expected to know what
251 // he/she is doing when calling this method.
252 return this[argumentOffset(argIndex)].jsValue();
253 }
254
255 static int thisArgumentOffset() { return argumentOffsetIncludingThis(0); }
256 JSValue thisValue() { return this[thisArgumentOffset()].jsValue(); }
257 void setThisValue(JSValue value) { this[thisArgumentOffset()] = value; }
258
259 // Under the constructor implemented in C++, thisValue holds the newTarget instead of the automatically constructed value.
260 // The result of this function is only effective under the "construct" context.
261 JSValue newTarget() { return thisValue(); }
262
263 JSValue argumentAfterCapture(size_t argument);
264
265 static int offsetFor(size_t argumentCountIncludingThis) { return argumentCountIncludingThis + CallFrameSlot::thisArgument - 1; }
266
267 static CallFrame* noCaller() { return nullptr; }
268 bool isGlobalExec() const
269 {
270 return callerFrameAndPC().callerFrame == noCaller() && callerFrameAndPC().returnPC == nullptr;
271 }
272
273 void convertToStackOverflowFrame(VM&, CodeBlock* codeBlockToKeepAliveUntilFrameIsUnwound);
274 bool isStackOverflowFrame() const;
275 bool isWasmFrame() const;
276
277 void setArgumentCountIncludingThis(int count) { static_cast<Register*>(this)[CallFrameSlot::argumentCount].payload() = count; }
278 void setCallee(JSObject* callee) { static_cast<Register*>(this)[CallFrameSlot::callee] = callee; }
279 void setCodeBlock(CodeBlock* codeBlock) { static_cast<Register*>(this)[CallFrameSlot::codeBlock] = codeBlock; }
280 void setReturnPC(void* value) { callerFrameAndPC().returnPC = reinterpret_cast<const Instruction*>(value); }
281
282 String friendlyFunctionName();
283
284 // CallFrame::iterate() expects a Functor that implements the following method:
285 // StackVisitor::Status operator()(StackVisitor&) const;
286 // FIXME: This method is improper. We rely on the fact that we can call it with a null
287 // receiver. We should always be using StackVisitor directly.
288 // It's only valid to call this from a non-wasm top frame.
289 template <StackVisitor::EmptyEntryFrameAction action = StackVisitor::ContinueIfTopEntryFrameIsEmpty, typename Functor> void iterate(const Functor& functor)
290 {
291 VM* vm;
292 void* rawThis = this;
293 if (!!rawThis) {
294 RELEASE_ASSERT(callee().isCell());
295 vm = &this->vm();
296 } else
297 vm = nullptr;
298 StackVisitor::visit<action, Functor>(this, vm, functor);
299 }
300
301 void dump(PrintStream&);
302 JS_EXPORT_PRIVATE const char* describeFrame();
303
304 private:
305
306 ExecState();
307 ~ExecState();
308
309 Register* topOfFrameInternal();
310
311 // The following are for internal use in debugging and verification
312 // code only and not meant as an API for general usage:
313
314 size_t argIndexForRegister(Register* reg)
315 {
316 // The register at 'offset' number of slots from the frame pointer
317 // i.e.
318 // reg = frame[offset];
319 // ==> reg = frame + offset;
320 // ==> offset = reg - frame;
321 int offset = reg - this->registers();
322
323 // The offset is defined (based on argumentOffset()) to be:
324 // offset = CallFrameSlot::firstArgument - argIndex;
325 // Hence:
326 // argIndex = CallFrameSlot::firstArgument - offset;
327 size_t argIndex = offset - CallFrameSlot::firstArgument;
328 return argIndex;
329 }
330
331 CallerFrameAndPC& callerFrameAndPC() { return *reinterpret_cast<CallerFrameAndPC*>(this); }
332 const CallerFrameAndPC& callerFrameAndPC() const { return *reinterpret_cast<const CallerFrameAndPC*>(this); }
333 SUPPRESS_ASAN const CallerFrameAndPC& unsafeCallerFrameAndPC() const { return *reinterpret_cast<const CallerFrameAndPC*>(this); }
334 };
335
336} // namespace JSC
337