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-rw-r--r--ARMeilleure/Signal/NativeSignalHandler.cs327
1 files changed, 327 insertions, 0 deletions
diff --git a/ARMeilleure/Signal/NativeSignalHandler.cs b/ARMeilleure/Signal/NativeSignalHandler.cs
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+++ b/ARMeilleure/Signal/NativeSignalHandler.cs
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+using ARMeilleure.IntermediateRepresentation;
+using ARMeilleure.Translation;
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+using static ARMeilleure.IntermediateRepresentation.OperandHelper;
+
+namespace ARMeilleure.Signal
+{
+ [StructLayout(LayoutKind.Sequential, Pack = 1)]
+ struct SignalHandlerRange
+ {
+ public int IsActive;
+ public nuint RangeAddress;
+ public nuint RangeEndAddress;
+ public IntPtr ActionPointer;
+ }
+
+ [StructLayout(LayoutKind.Sequential, Pack = 1)]
+ struct SignalHandlerConfig
+ {
+ /// <summary>
+ /// The byte offset of the faulting address in the SigInfo or ExceptionRecord struct.
+ /// </summary>
+ public int StructAddressOffset;
+
+ /// <summary>
+ /// The byte offset of the write flag in the SigInfo or ExceptionRecord struct.
+ /// </summary>
+ public int StructWriteOffset;
+
+ /// <summary>
+ /// The sigaction handler that was registered before this one. (unix only)
+ /// </summary>
+ public nuint UnixOldSigaction;
+
+ /// <summary>
+ /// The type of the previous sigaction. True for the 3 argument variant. (unix only)
+ /// </summary>
+ public int UnixOldSigaction3Arg;
+
+ public SignalHandlerRange Range0;
+ public SignalHandlerRange Range1;
+ public SignalHandlerRange Range2;
+ public SignalHandlerRange Range3;
+ public SignalHandlerRange Range4;
+ public SignalHandlerRange Range5;
+ public SignalHandlerRange Range6;
+ public SignalHandlerRange Range7;
+ }
+
+ public static class NativeSignalHandler
+ {
+ private delegate void UnixExceptionHandler(int sig, IntPtr info, IntPtr ucontext);
+ [UnmanagedFunctionPointer(CallingConvention.Winapi)]
+ private delegate int VectoredExceptionHandler(IntPtr exceptionInfo);
+
+ private 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 const ulong PageSize = 0x1000;
+ private const ulong PageMask = PageSize - 1;
+
+ private static IntPtr _handlerConfig;
+ private static IntPtr _signalHandlerPtr;
+ private static IntPtr _signalHandlerHandle;
+
+ private static readonly object _lock = new object();
+ private static bool _initialized;
+
+ static NativeSignalHandler()
+ {
+ _handlerConfig = Marshal.AllocHGlobal(Unsafe.SizeOf<SignalHandlerConfig>());
+ ref SignalHandlerConfig config = ref GetConfigRef();
+
+ config = new SignalHandlerConfig();
+ }
+
+ public static void InitializeSignalHandler()
+ {
+ if (_initialized) return;
+
+ lock (_lock)
+ {
+ if (_initialized) return;
+
+ Translator.PreparePool();
+
+ bool unix = RuntimeInformation.IsOSPlatform(OSPlatform.Linux) || RuntimeInformation.IsOSPlatform(OSPlatform.OSX);
+ ref SignalHandlerConfig config = ref GetConfigRef();
+
+ if (unix)
+ {
+ // Unix siginfo struct locations.
+ // NOTE: These are incredibly likely to be different between kernel version and architectures.
+
+ config.StructAddressOffset = 16; // si_addr
+ config.StructWriteOffset = 8; // si_code
+
+ _signalHandlerPtr = Marshal.GetFunctionPointerForDelegate(GenerateUnixSignalHandler(_handlerConfig));
+
+ SigAction old = UnixSignalHandlerRegistration.RegisterExceptionHandler(_signalHandlerPtr);
+ config.UnixOldSigaction = (nuint)(ulong)old.sa_handler;
+ config.UnixOldSigaction3Arg = old.sa_flags & 4;
+ }
+ else
+ {
+ config.StructAddressOffset = 40; // ExceptionInformation1
+ config.StructWriteOffset = 32; // ExceptionInformation0
+
+ _signalHandlerPtr = Marshal.GetFunctionPointerForDelegate(GenerateWindowsSignalHandler(_handlerConfig));
+
+ _signalHandlerHandle = WindowsSignalHandlerRegistration.RegisterExceptionHandler(_signalHandlerPtr);
+ }
+
+ Translator.ResetPool();
+
+ Translator.DisposePools();
+
+ _initialized = true;
+ }
+ }
+
+ private static unsafe ref SignalHandlerConfig GetConfigRef()
+ {
+ return ref Unsafe.AsRef<SignalHandlerConfig>((void*)_handlerConfig);
+ }
+
+ public static unsafe bool AddTrackedRegion(nuint address, nuint endAddress, IntPtr action)
+ {
+ var ranges = &((SignalHandlerConfig*)_handlerConfig)->Range0;
+
+ for (int i = 0; i < MaxTrackedRanges; i++)
+ {
+ if (ranges[i].IsActive == 0)
+ {
+ ranges[i].RangeAddress = address;
+ ranges[i].RangeEndAddress = endAddress;
+ ranges[i].ActionPointer = action;
+ ranges[i].IsActive = 1;
+
+ return true;
+ }
+ }
+
+ return false;
+ }
+
+ public static unsafe bool RemoveTrackedRegion(nuint address)
+ {
+ var ranges = &((SignalHandlerConfig*)_handlerConfig)->Range0;
+
+ for (int i = 0; i < MaxTrackedRanges; i++)
+ {
+ if (ranges[i].IsActive == 1 && ranges[i].RangeAddress == address)
+ {
+ ranges[i].IsActive = 0;
+
+ return true;
+ }
+ }
+
+ return false;
+ }
+
+ private static Operand EmitGenericRegionCheck(EmitterContext context, IntPtr signalStructPtr, Operand faultAddress, Operand isWrite)
+ {
+ 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 * Unsafe.SizeOf<SignalHandlerRange>());
+
+ 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.Less)
+ );
+
+ // Only call tracking if in range.
+ context.BranchIfFalse(nextLabel, inRange, BasicBlockFrequency.Cold);
+
+ context.Copy(inRegionLocal, Const(1));
+ 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.Call(trackingActionPtr, OperandType.I32, offset, Const(PageSize), isWrite);
+
+ context.Branch(endLabel);
+
+ context.MarkLabel(nextLabel);
+ }
+
+ context.MarkLabel(endLabel);
+
+ return context.Copy(inRegionLocal);
+ }
+
+ private static UnixExceptionHandler GenerateUnixSignalHandler(IntPtr signalStructPtr)
+ {
+ EmitterContext context = new EmitterContext();
+
+ // (int sig, SigInfo* sigInfo, void* ucontext)
+ Operand sigInfoPtr = context.LoadArgument(OperandType.I64, 1);
+
+ Operand structAddressOffset = context.Load(OperandType.I64, Const((ulong)signalStructPtr + StructAddressOffset));
+ Operand structWriteOffset = context.Load(OperandType.I64, Const((ulong)signalStructPtr + StructWriteOffset));
+
+ Operand faultAddress = context.Load(OperandType.I64, context.Add(sigInfoPtr, context.ZeroExtend32(OperandType.I64, structAddressOffset)));
+ Operand writeFlag = context.Load(OperandType.I64, context.Add(sigInfoPtr, context.ZeroExtend32(OperandType.I64, structWriteOffset)));
+
+ Operand isWrite = context.ICompareNotEqual(writeFlag, Const(0L)); // Normalize to 0/1.
+
+ Operand isInRegion = EmitGenericRegionCheck(context, signalStructPtr, faultAddress, isWrite);
+
+ 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<UnixExceptionHandler>(cfg, argTypes, OperandType.None, CompilerOptions.HighCq);
+ }
+
+ private static VectoredExceptionHandler GenerateWindowsSignalHandler(IntPtr signalStructPtr)
+ {
+ EmitterContext context = new EmitterContext();
+
+ // (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);
+
+ 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<VectoredExceptionHandler>(cfg, argTypes, OperandType.I32, CompilerOptions.HighCq);
+ }
+ }
+}