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
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
|
using ARMeilleure.IntermediateRepresentation;
using ARMeilleure.Translation;
using System;
using System.Runtime.InteropServices;
using static ARMeilleure.IntermediateRepresentation.Operand.Factory;
namespace ARMeilleure.Signal
{
public static class NativeSignalHandlerGenerator
{
public const int MaxTrackedRanges = 8;
private const int StructAddressOffset = 0;
private const int StructWriteOffset = 4;
private const int UnixOldSigaction = 8;
private const int UnixOldSigaction3Arg = 16;
private const int RangeOffset = 20;
private const int EXCEPTION_CONTINUE_SEARCH = 0;
private const int EXCEPTION_CONTINUE_EXECUTION = -1;
private const uint EXCEPTION_ACCESS_VIOLATION = 0xc0000005;
private static Operand EmitGenericRegionCheck(EmitterContext context, IntPtr signalStructPtr, Operand faultAddress, Operand isWrite, int rangeStructSize, ulong pageSize)
{
ulong pageMask = pageSize - 1;
Operand inRegionLocal = context.AllocateLocal(OperandType.I32);
context.Copy(inRegionLocal, Const(0));
Operand endLabel = Label();
for (int i = 0; i < MaxTrackedRanges; i++)
{
ulong rangeBaseOffset = (ulong)(RangeOffset + i * rangeStructSize);
Operand nextLabel = Label();
Operand isActive = context.Load(OperandType.I32, Const((ulong)signalStructPtr + rangeBaseOffset));
context.BranchIfFalse(nextLabel, isActive);
Operand rangeAddress = context.Load(OperandType.I64, Const((ulong)signalStructPtr + rangeBaseOffset + 4));
Operand rangeEndAddress = context.Load(OperandType.I64, Const((ulong)signalStructPtr + rangeBaseOffset + 12));
// Is the fault address within this tracked region?
Operand inRange = context.BitwiseAnd(
context.ICompare(faultAddress, rangeAddress, Comparison.GreaterOrEqualUI),
context.ICompare(faultAddress, rangeEndAddress, Comparison.LessUI));
// Only call tracking if in range.
context.BranchIfFalse(nextLabel, inRange, BasicBlockFrequency.Cold);
Operand offset = context.BitwiseAnd(context.Subtract(faultAddress, rangeAddress), Const(~pageMask));
// Call the tracking action, with the pointer's relative offset to the base address.
Operand trackingActionPtr = context.Load(OperandType.I64, Const((ulong)signalStructPtr + rangeBaseOffset + 20));
context.Copy(inRegionLocal, Const(0));
Operand skipActionLabel = Label();
// Tracking action should be non-null to call it, otherwise assume false return.
context.BranchIfFalse(skipActionLabel, trackingActionPtr);
Operand result = context.Call(trackingActionPtr, OperandType.I32, offset, Const(pageSize), isWrite);
context.Copy(inRegionLocal, result);
context.MarkLabel(skipActionLabel);
// If the tracking action returns false or does not exist, it might be an invalid access due to a partial overlap on Windows.
if (OperatingSystem.IsWindows())
{
context.BranchIfTrue(endLabel, inRegionLocal);
context.Copy(inRegionLocal, WindowsPartialUnmapHandler.EmitRetryFromAccessViolation(context));
}
context.Branch(endLabel);
context.MarkLabel(nextLabel);
}
context.MarkLabel(endLabel);
return context.Copy(inRegionLocal);
}
private static Operand GenerateUnixFaultAddress(EmitterContext context, Operand sigInfoPtr)
{
ulong structAddressOffset = OperatingSystem.IsMacOS() ? 24ul : 16ul; // si_addr
return context.Load(OperandType.I64, context.Add(sigInfoPtr, Const(structAddressOffset)));
}
private static Operand GenerateUnixWriteFlag(EmitterContext context, Operand ucontextPtr)
{
if (OperatingSystem.IsMacOS())
{
const ulong McontextOffset = 48; // uc_mcontext
Operand ctxPtr = context.Load(OperandType.I64, context.Add(ucontextPtr, Const(McontextOffset)));
if (RuntimeInformation.ProcessArchitecture == Architecture.Arm64)
{
const ulong EsrOffset = 8; // __es.__esr
Operand esr = context.Load(OperandType.I64, context.Add(ctxPtr, Const(EsrOffset)));
return context.BitwiseAnd(esr, Const(0x40ul));
}
else if (RuntimeInformation.ProcessArchitecture == Architecture.X64)
{
const ulong ErrOffset = 4; // __es.__err
Operand err = context.Load(OperandType.I64, context.Add(ctxPtr, Const(ErrOffset)));
return context.BitwiseAnd(err, Const(2ul));
}
}
else if (OperatingSystem.IsLinux())
{
if (RuntimeInformation.ProcessArchitecture == Architecture.Arm64)
{
Operand auxPtr = context.AllocateLocal(OperandType.I64);
Operand loopLabel = Label();
Operand successLabel = Label();
const ulong AuxOffset = 464; // uc_mcontext.__reserved
const uint EsrMagic = 0x45535201;
context.Copy(auxPtr, context.Add(ucontextPtr, Const(AuxOffset)));
context.MarkLabel(loopLabel);
// _aarch64_ctx::magic
Operand magic = context.Load(OperandType.I32, auxPtr);
// _aarch64_ctx::size
Operand size = context.Load(OperandType.I32, context.Add(auxPtr, Const(4ul)));
context.BranchIf(successLabel, magic, Const(EsrMagic), Comparison.Equal);
context.Copy(auxPtr, context.Add(auxPtr, context.ZeroExtend32(OperandType.I64, size)));
context.Branch(loopLabel);
context.MarkLabel(successLabel);
// esr_context::esr
Operand esr = context.Load(OperandType.I64, context.Add(auxPtr, Const(8ul)));
return context.BitwiseAnd(esr, Const(0x40ul));
}
else if (RuntimeInformation.ProcessArchitecture == Architecture.X64)
{
const int ErrOffset = 192; // uc_mcontext.gregs[REG_ERR]
Operand err = context.Load(OperandType.I64, context.Add(ucontextPtr, Const(ErrOffset)));
return context.BitwiseAnd(err, Const(2ul));
}
}
throw new PlatformNotSupportedException();
}
public static byte[] GenerateUnixSignalHandler(IntPtr signalStructPtr, int rangeStructSize, ulong pageSize)
{
EmitterContext context = new();
// (int sig, SigInfo* sigInfo, void* ucontext)
Operand sigInfoPtr = context.LoadArgument(OperandType.I64, 1);
Operand ucontextPtr = context.LoadArgument(OperandType.I64, 2);
Operand faultAddress = GenerateUnixFaultAddress(context, sigInfoPtr);
Operand writeFlag = GenerateUnixWriteFlag(context, ucontextPtr);
Operand isWrite = context.ICompareNotEqual(writeFlag, Const(0L)); // Normalize to 0/1.
Operand isInRegion = EmitGenericRegionCheck(context, signalStructPtr, faultAddress, isWrite, rangeStructSize, pageSize);
Operand endLabel = Label();
context.BranchIfTrue(endLabel, isInRegion);
Operand unixOldSigaction = context.Load(OperandType.I64, Const((ulong)signalStructPtr + UnixOldSigaction));
Operand unixOldSigaction3Arg = context.Load(OperandType.I64, Const((ulong)signalStructPtr + UnixOldSigaction3Arg));
Operand threeArgLabel = Label();
context.BranchIfTrue(threeArgLabel, unixOldSigaction3Arg);
context.Call(unixOldSigaction, OperandType.None, context.LoadArgument(OperandType.I32, 0));
context.Branch(endLabel);
context.MarkLabel(threeArgLabel);
context.Call(unixOldSigaction,
OperandType.None,
context.LoadArgument(OperandType.I32, 0),
sigInfoPtr,
context.LoadArgument(OperandType.I64, 2)
);
context.MarkLabel(endLabel);
context.Return();
ControlFlowGraph cfg = context.GetControlFlowGraph();
OperandType[] argTypes = new OperandType[] { OperandType.I32, OperandType.I64, OperandType.I64 };
return Compiler.Compile(cfg, argTypes, OperandType.None, CompilerOptions.HighCq, RuntimeInformation.ProcessArchitecture).Code;
}
public static byte[] GenerateWindowsSignalHandler(IntPtr signalStructPtr, int rangeStructSize, ulong pageSize)
{
EmitterContext context = new();
// (ExceptionPointers* exceptionInfo)
Operand exceptionInfoPtr = context.LoadArgument(OperandType.I64, 0);
Operand exceptionRecordPtr = context.Load(OperandType.I64, exceptionInfoPtr);
// First thing's first - this catches a number of exceptions, but we only want access violations.
Operand validExceptionLabel = Label();
Operand exceptionCode = context.Load(OperandType.I32, exceptionRecordPtr);
context.BranchIf(validExceptionLabel, exceptionCode, Const(EXCEPTION_ACCESS_VIOLATION), Comparison.Equal);
context.Return(Const(EXCEPTION_CONTINUE_SEARCH)); // Don't handle this one.
context.MarkLabel(validExceptionLabel);
// Next, read the address of the invalid access, and whether it is a write or not.
Operand structAddressOffset = context.Load(OperandType.I32, Const((ulong)signalStructPtr + StructAddressOffset));
Operand structWriteOffset = context.Load(OperandType.I32, Const((ulong)signalStructPtr + StructWriteOffset));
Operand faultAddress = context.Load(OperandType.I64, context.Add(exceptionRecordPtr, context.ZeroExtend32(OperandType.I64, structAddressOffset)));
Operand writeFlag = context.Load(OperandType.I64, context.Add(exceptionRecordPtr, context.ZeroExtend32(OperandType.I64, structWriteOffset)));
Operand isWrite = context.ICompareNotEqual(writeFlag, Const(0L)); // Normalize to 0/1.
Operand isInRegion = EmitGenericRegionCheck(context, signalStructPtr, faultAddress, isWrite, rangeStructSize, pageSize);
Operand endLabel = Label();
// If the region check result is false, then run the next vectored exception handler.
context.BranchIfTrue(endLabel, isInRegion);
context.Return(Const(EXCEPTION_CONTINUE_SEARCH));
context.MarkLabel(endLabel);
// Otherwise, return to execution.
context.Return(Const(EXCEPTION_CONTINUE_EXECUTION));
// Compile and return the function.
ControlFlowGraph cfg = context.GetControlFlowGraph();
OperandType[] argTypes = new OperandType[] { OperandType.I64 };
return Compiler.Compile(cfg, argTypes, OperandType.I32, CompilerOptions.HighCq, RuntimeInformation.ProcessArchitecture).Code;
}
}
}
|
