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1 // Copyright 2019 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_DIAGNOSTICS_UNWINDING_INFO_WIN64_H_
6 #define V8_DIAGNOSTICS_UNWINDING_INFO_WIN64_H_
7 
8 #include "include/v8.h"
9 #include "include/v8config.h"
10 #include "src/common/globals.h"
11 
12 #if defined(V8_OS_WIN64)
13 #include "src/base/win32-headers.h"
14 
15 namespace v8 {
16 namespace internal {
17 
18 namespace win64_unwindinfo {
19 
20 #define CRASH_HANDLER_FUNCTION_NAME CrashForExceptionInNonABICompliantCodeRange
21 #define CRASH_HANDLER_FUNCTION_NAME_STRING \
22   "CrashForExceptionInNonABICompliantCodeRange"
23 
24 static const int kOSPageSize = 4096;
25 
26 /**
27  * Returns true if V8 is configured to emit unwinding data for embedded in the
28  * pdata/xdata sections of the executable. Currently, this happens when V8 is
29  * built with "v8_win64_unwinding_info = true".
30  */
31 bool CanEmitUnwindInfoForBuiltins();
32 
33 /**
34  * Returns true if V8 if we can register unwinding data for the whole code range
35  * of an isolate or Wasm module. The first page of the code range is reserved
36  * and writable, to be used to store unwind data, as documented in:
37  * https://docs.microsoft.com/en-us/cpp/build/exception-handling-x64.
38  * In jitless mode V8 does not allocate any executable memory itself so the only
39  * non-abi-compliant code range is in the embedded blob.
40  */
41 bool CanRegisterUnwindInfoForNonABICompliantCodeRange();
42 
43 /**
44  * Registers a custom exception handler for exceptions in V8-generated code.
45  */
46 void SetUnhandledExceptionCallback(
47     v8::UnhandledExceptionCallback unhandled_exception_callback);
48 
49 void RegisterNonABICompliantCodeRange(void* start, size_t size_in_bytes);
50 void UnregisterNonABICompliantCodeRange(void* start);
51 
52 /**
53  * Default count of RUNTIME_FUNCTION needed. For Windows X64, 1 RUNTIME_FUNCTION
54  * covers 4GB range which is sufficient to cover the whole code range of an
55  * isolate or Wasm module. For Windows ARM64, 1 RUNTIME_FUNCTION covers
56  * kMaxFunctionLength bytes so multiple RUNTIME_FUNCTION structs could be needed
57  * to cover the whole code range of an isolate or Wasm module. The extra
58  * RUNTIME_FUNCTIONs are assumed following the first one in the reserved page.
59  */
60 static const uint32_t kDefaultRuntimeFunctionCount = 1;
61 
62 #if defined(V8_OS_WIN_X64)
63 
64 static const int kPushRbpInstructionLength = 1;
65 static const int kMovRbpRspInstructionLength = 3;
66 static const int kRbpPrefixCodes = 2;
67 static const int kRbpPrefixLength =
68     kPushRbpInstructionLength + kMovRbpRspInstructionLength;
69 
70 /**
71  * Returns a vector of bytes that contains the Win X64 unwind data used for all
72  * V8 builtin functions.
73  */
74 std::vector<uint8_t> GetUnwindInfoForBuiltinFunctions();
75 
76 class BuiltinUnwindInfo {
77  public:
BuiltinUnwindInfo()78   BuiltinUnwindInfo() : is_leaf_function_(true) {}
BuiltinUnwindInfo(const std::vector<int> & fp_offsets)79   explicit BuiltinUnwindInfo(const std::vector<int>& fp_offsets)
80       : is_leaf_function_(false), fp_offsets_(fp_offsets) {}
81 
is_leaf_function()82   bool is_leaf_function() const { return is_leaf_function_; }
fp_offsets()83   const std::vector<int>& fp_offsets() const { return fp_offsets_; }
84 
85  private:
86   bool is_leaf_function_;
87   std::vector<int> fp_offsets_;
88 };
89 
90 class XdataEncoder {
91  public:
XdataEncoder(const Assembler & assembler)92   explicit XdataEncoder(const Assembler& assembler)
93       : assembler_(assembler), current_frame_code_offset_(-1) {}
94 
95   void onPushRbp();
96   void onMovRbpRsp();
97 
unwinding_info()98   BuiltinUnwindInfo unwinding_info() const {
99     return BuiltinUnwindInfo(fp_offsets_);
100   }
101 
102  private:
103   const Assembler& assembler_;
104   std::vector<int> fp_offsets_;
105   int current_frame_code_offset_;
106 };
107 
108 #elif defined(V8_OS_WIN_ARM64)
109 
110 /**
111  * Base on below doc, unwind record has 18 bits (unsigned) to encode function
112  * length, besides 2 LSB which are always 0.
113  * https://docs.microsoft.com/en-us/cpp/build/arm64-exception-handling#xdata-records
114  */
115 static const int kMaxFunctionLength = ((1 << 18) - 1) << 2;
116 
117 struct FrameOffsets {
118   FrameOffsets();
119   bool IsDefault() const;
120   int fp_to_saved_caller_fp;
121   int fp_to_caller_sp;
122 };
123 
124 /**
125  * Returns a vector of bytes that contains the Win ARM64 unwind data used for
126  * all V8 builtin functions.
127  *
128  * func_len: length in bytes of current function/region to unwind.
129  * fp_adjustment: offset of the saved caller's fp based on fp in current frame.
130  *                this is necessary to encode unwind data for Windows stack
131  *                unwinder to find correct caller's fp.
132  */
133 std::vector<uint8_t> GetUnwindInfoForBuiltinFunction(
134     uint32_t func_len, FrameOffsets fp_adjustment);
135 class BuiltinUnwindInfo {
136  public:
BuiltinUnwindInfo()137   BuiltinUnwindInfo() : is_leaf_function_(true) {}
BuiltinUnwindInfo(const std::vector<int> & fp_offsets,const std::vector<FrameOffsets> & fp_adjustments)138   explicit BuiltinUnwindInfo(const std::vector<int>& fp_offsets,
139                              const std::vector<FrameOffsets>& fp_adjustments)
140       : is_leaf_function_(false),
141         fp_offsets_(fp_offsets),
142         fp_adjustments_(fp_adjustments) {}
143 
fp_adjustments()144   const std::vector<FrameOffsets>& fp_adjustments() const {
145     return fp_adjustments_;
146   }
147 
is_leaf_function()148   bool is_leaf_function() const { return is_leaf_function_; }
fp_offsets()149   const std::vector<int>& fp_offsets() const { return fp_offsets_; }
150 
151  private:
152   bool is_leaf_function_;
153   std::vector<int> fp_offsets_;
154   std::vector<FrameOffsets> fp_adjustments_;
155 };
156 
157 class XdataEncoder {
158  public:
XdataEncoder(const Assembler & assembler)159   explicit XdataEncoder(const Assembler& assembler)
160       : assembler_(assembler), current_frame_code_offset_(-1) {}
161 
162   void onSaveFpLr();
163   void onFramePointerAdjustment(int fp_to_saved_caller_fp, int fp_to_caller_sp);
164 
unwinding_info()165   BuiltinUnwindInfo unwinding_info() const {
166     return BuiltinUnwindInfo(fp_offsets_, fp_adjustments_);
167   }
168 
169  private:
170   const Assembler& assembler_;
171   std::vector<int> fp_offsets_;
172   int current_frame_code_offset_;
173   FrameOffsets current_frame_adjustment_;
174   std::vector<FrameOffsets> fp_adjustments_;
175 };
176 
177 #endif
178 
179 }  // namespace win64_unwindinfo
180 }  // namespace internal
181 }  // namespace v8
182 
183 #endif  // V8_OS_WIN64
184 
185 #endif  // V8_DIAGNOSTICS_UNWINDING_INFO_WIN64_H_
186