321 lines
13 KiB
C#
321 lines
13 KiB
C#
using ARMeilleure.IntermediateRepresentation;
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using ARMeilleure.Translation;
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using System;
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using System.Runtime.CompilerServices;
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using System.Runtime.InteropServices;
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using static ARMeilleure.IntermediateRepresentation.Operand.Factory;
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namespace ARMeilleure.Signal
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{
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[StructLayout(LayoutKind.Sequential, Pack = 1)]
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struct SignalHandlerRange
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{
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public int IsActive;
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public nuint RangeAddress;
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public nuint RangeEndAddress;
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public IntPtr ActionPointer;
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}
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[StructLayout(LayoutKind.Sequential, Pack = 1)]
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struct SignalHandlerConfig
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{
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/// <summary>
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/// The byte offset of the faulting address in the SigInfo or ExceptionRecord struct.
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/// </summary>
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public int StructAddressOffset;
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/// <summary>
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/// The byte offset of the write flag in the SigInfo or ExceptionRecord struct.
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/// </summary>
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public int StructWriteOffset;
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/// <summary>
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/// The sigaction handler that was registered before this one. (unix only)
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/// </summary>
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public nuint UnixOldSigaction;
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/// <summary>
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/// The type of the previous sigaction. True for the 3 argument variant. (unix only)
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/// </summary>
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public int UnixOldSigaction3Arg;
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public SignalHandlerRange Range0;
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public SignalHandlerRange Range1;
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public SignalHandlerRange Range2;
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public SignalHandlerRange Range3;
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public SignalHandlerRange Range4;
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public SignalHandlerRange Range5;
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public SignalHandlerRange Range6;
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public SignalHandlerRange Range7;
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}
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public static class NativeSignalHandler
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{
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private delegate void UnixExceptionHandler(int sig, IntPtr info, IntPtr ucontext);
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[UnmanagedFunctionPointer(CallingConvention.Winapi)]
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private delegate int VectoredExceptionHandler(IntPtr exceptionInfo);
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private const int MaxTrackedRanges = 8;
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private const int StructAddressOffset = 0;
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private const int StructWriteOffset = 4;
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private const int UnixOldSigaction = 8;
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private const int UnixOldSigaction3Arg = 16;
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private const int RangeOffset = 20;
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private const int EXCEPTION_CONTINUE_SEARCH = 0;
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private const int EXCEPTION_CONTINUE_EXECUTION = -1;
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private const uint EXCEPTION_ACCESS_VIOLATION = 0xc0000005;
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private const ulong PageSize = 0x1000;
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private const ulong PageMask = PageSize - 1;
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private static IntPtr _handlerConfig;
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private static IntPtr _signalHandlerPtr;
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private static IntPtr _signalHandlerHandle;
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private static readonly object _lock = new object();
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private static bool _initialized;
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static NativeSignalHandler()
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{
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_handlerConfig = Marshal.AllocHGlobal(Unsafe.SizeOf<SignalHandlerConfig>());
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ref SignalHandlerConfig config = ref GetConfigRef();
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config = new SignalHandlerConfig();
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}
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public static void InitializeSignalHandler()
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{
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if (_initialized) return;
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lock (_lock)
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{
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if (_initialized) return;
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bool unix = OperatingSystem.IsLinux() || OperatingSystem.IsMacOS();
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ref SignalHandlerConfig config = ref GetConfigRef();
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if (unix)
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{
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// Unix siginfo struct locations.
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// NOTE: These are incredibly likely to be different between kernel version and architectures.
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config.StructAddressOffset = 16; // si_addr
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config.StructWriteOffset = 8; // si_code
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_signalHandlerPtr = Marshal.GetFunctionPointerForDelegate(GenerateUnixSignalHandler(_handlerConfig));
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SigAction old = UnixSignalHandlerRegistration.RegisterExceptionHandler(_signalHandlerPtr);
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config.UnixOldSigaction = (nuint)(ulong)old.sa_handler;
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config.UnixOldSigaction3Arg = old.sa_flags & 4;
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}
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else
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{
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config.StructAddressOffset = 40; // ExceptionInformation1
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config.StructWriteOffset = 32; // ExceptionInformation0
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_signalHandlerPtr = Marshal.GetFunctionPointerForDelegate(GenerateWindowsSignalHandler(_handlerConfig));
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_signalHandlerHandle = WindowsSignalHandlerRegistration.RegisterExceptionHandler(_signalHandlerPtr);
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}
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_initialized = true;
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}
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}
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private static unsafe ref SignalHandlerConfig GetConfigRef()
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{
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return ref Unsafe.AsRef<SignalHandlerConfig>((void*)_handlerConfig);
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}
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public static unsafe bool AddTrackedRegion(nuint address, nuint endAddress, IntPtr action)
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{
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var ranges = &((SignalHandlerConfig*)_handlerConfig)->Range0;
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for (int i = 0; i < MaxTrackedRanges; i++)
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{
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if (ranges[i].IsActive == 0)
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{
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ranges[i].RangeAddress = address;
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ranges[i].RangeEndAddress = endAddress;
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ranges[i].ActionPointer = action;
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ranges[i].IsActive = 1;
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return true;
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}
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}
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return false;
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}
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public static unsafe bool RemoveTrackedRegion(nuint address)
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{
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var ranges = &((SignalHandlerConfig*)_handlerConfig)->Range0;
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for (int i = 0; i < MaxTrackedRanges; i++)
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{
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if (ranges[i].IsActive == 1 && ranges[i].RangeAddress == address)
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{
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ranges[i].IsActive = 0;
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return true;
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}
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}
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return false;
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}
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private static Operand EmitGenericRegionCheck(EmitterContext context, IntPtr signalStructPtr, Operand faultAddress, Operand isWrite)
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{
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Operand inRegionLocal = context.AllocateLocal(OperandType.I32);
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context.Copy(inRegionLocal, Const(0));
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Operand endLabel = Label();
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for (int i = 0; i < MaxTrackedRanges; i++)
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{
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ulong rangeBaseOffset = (ulong)(RangeOffset + i * Unsafe.SizeOf<SignalHandlerRange>());
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Operand nextLabel = Label();
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Operand isActive = context.Load(OperandType.I32, Const((ulong)signalStructPtr + rangeBaseOffset));
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context.BranchIfFalse(nextLabel, isActive);
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Operand rangeAddress = context.Load(OperandType.I64, Const((ulong)signalStructPtr + rangeBaseOffset + 4));
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Operand rangeEndAddress = context.Load(OperandType.I64, Const((ulong)signalStructPtr + rangeBaseOffset + 12));
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// Is the fault address within this tracked region?
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Operand inRange = context.BitwiseAnd(
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context.ICompare(faultAddress, rangeAddress, Comparison.GreaterOrEqualUI),
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context.ICompare(faultAddress, rangeEndAddress, Comparison.Less)
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);
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// Only call tracking if in range.
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context.BranchIfFalse(nextLabel, inRange, BasicBlockFrequency.Cold);
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context.Copy(inRegionLocal, Const(1));
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Operand offset = context.BitwiseAnd(context.Subtract(faultAddress, rangeAddress), Const(~PageMask));
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// Call the tracking action, with the pointer's relative offset to the base address.
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Operand trackingActionPtr = context.Load(OperandType.I64, Const((ulong)signalStructPtr + rangeBaseOffset + 20));
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context.Call(trackingActionPtr, OperandType.I32, offset, Const(PageSize), isWrite, Const(0));
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context.Branch(endLabel);
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context.MarkLabel(nextLabel);
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}
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context.MarkLabel(endLabel);
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return context.Copy(inRegionLocal);
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}
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private static UnixExceptionHandler GenerateUnixSignalHandler(IntPtr signalStructPtr)
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{
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EmitterContext context = new EmitterContext();
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// (int sig, SigInfo* sigInfo, void* ucontext)
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Operand sigInfoPtr = context.LoadArgument(OperandType.I64, 1);
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Operand structAddressOffset = context.Load(OperandType.I64, Const((ulong)signalStructPtr + StructAddressOffset));
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Operand structWriteOffset = context.Load(OperandType.I64, Const((ulong)signalStructPtr + StructWriteOffset));
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Operand faultAddress = context.Load(OperandType.I64, context.Add(sigInfoPtr, context.ZeroExtend32(OperandType.I64, structAddressOffset)));
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Operand writeFlag = context.Load(OperandType.I64, context.Add(sigInfoPtr, context.ZeroExtend32(OperandType.I64, structWriteOffset)));
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Operand isWrite = context.ICompareNotEqual(writeFlag, Const(0L)); // Normalize to 0/1.
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Operand isInRegion = EmitGenericRegionCheck(context, signalStructPtr, faultAddress, isWrite);
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Operand endLabel = Label();
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context.BranchIfTrue(endLabel, isInRegion);
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Operand unixOldSigaction = context.Load(OperandType.I64, Const((ulong)signalStructPtr + UnixOldSigaction));
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Operand unixOldSigaction3Arg = context.Load(OperandType.I64, Const((ulong)signalStructPtr + UnixOldSigaction3Arg));
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Operand threeArgLabel = Label();
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context.BranchIfTrue(threeArgLabel, unixOldSigaction3Arg);
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context.Call(unixOldSigaction, OperandType.None, context.LoadArgument(OperandType.I32, 0));
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context.Branch(endLabel);
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context.MarkLabel(threeArgLabel);
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context.Call(unixOldSigaction,
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OperandType.None,
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context.LoadArgument(OperandType.I32, 0),
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sigInfoPtr,
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context.LoadArgument(OperandType.I64, 2)
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);
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context.MarkLabel(endLabel);
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context.Return();
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ControlFlowGraph cfg = context.GetControlFlowGraph();
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OperandType[] argTypes = new OperandType[] { OperandType.I32, OperandType.I64, OperandType.I64 };
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return Compiler.Compile(cfg, argTypes, OperandType.None, CompilerOptions.HighCq).Map<UnixExceptionHandler>();
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}
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private static VectoredExceptionHandler GenerateWindowsSignalHandler(IntPtr signalStructPtr)
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{
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EmitterContext context = new EmitterContext();
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// (ExceptionPointers* exceptionInfo)
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Operand exceptionInfoPtr = context.LoadArgument(OperandType.I64, 0);
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Operand exceptionRecordPtr = context.Load(OperandType.I64, exceptionInfoPtr);
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// First thing's first - this catches a number of exceptions, but we only want access violations.
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Operand validExceptionLabel = Label();
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Operand exceptionCode = context.Load(OperandType.I32, exceptionRecordPtr);
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context.BranchIf(validExceptionLabel, exceptionCode, Const(EXCEPTION_ACCESS_VIOLATION), Comparison.Equal);
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context.Return(Const(EXCEPTION_CONTINUE_SEARCH)); // Don't handle this one.
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context.MarkLabel(validExceptionLabel);
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// Next, read the address of the invalid access, and whether it is a write or not.
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Operand structAddressOffset = context.Load(OperandType.I32, Const((ulong)signalStructPtr + StructAddressOffset));
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Operand structWriteOffset = context.Load(OperandType.I32, Const((ulong)signalStructPtr + StructWriteOffset));
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Operand faultAddress = context.Load(OperandType.I64, context.Add(exceptionRecordPtr, context.ZeroExtend32(OperandType.I64, structAddressOffset)));
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Operand writeFlag = context.Load(OperandType.I64, context.Add(exceptionRecordPtr, context.ZeroExtend32(OperandType.I64, structWriteOffset)));
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Operand isWrite = context.ICompareNotEqual(writeFlag, Const(0L)); // Normalize to 0/1.
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Operand isInRegion = EmitGenericRegionCheck(context, signalStructPtr, faultAddress, isWrite);
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Operand endLabel = Label();
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// If the region check result is false, then run the next vectored exception handler.
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context.BranchIfTrue(endLabel, isInRegion);
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context.Return(Const(EXCEPTION_CONTINUE_SEARCH));
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context.MarkLabel(endLabel);
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// Otherwise, return to execution.
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context.Return(Const(EXCEPTION_CONTINUE_EXECUTION));
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// Compile and return the function.
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ControlFlowGraph cfg = context.GetControlFlowGraph();
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OperandType[] argTypes = new OperandType[] { OperandType.I64 };
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return Compiler.Compile(cfg, argTypes, OperandType.I32, CompilerOptions.HighCq).Map<VectoredExceptionHandler>();
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}
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}
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}
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