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Fix reporting illegal instruction exception #107414

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merged 4 commits into from
Sep 21, 2024
Merged

Fix reporting illegal instruction exception #107414

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a1bf317
Fix reporting illegal instruction exception
janvorli Sep 5, 2024
69f6a7b
Make the illegal instruction fail fast on NativeAOT.
janvorli Sep 9, 2024
7f6a959
Update message and add two more hardware exceptions
janvorli Sep 19, 2024
e80673e
Fix build break
janvorli Sep 20, 2024
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20 changes: 20 additions & 0 deletions src/coreclr/nativeaot/Runtime.Base/src/System/Runtime/ExceptionHandling.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -326,6 +326,11 @@ internal static Exception GetClasslibException(ExceptionIDs id, IntPtr address)
ExceptionIDs.NullReference => new NullReferenceException(),
ExceptionIDs.OutOfMemory => new OutOfMemoryException(),
ExceptionIDs.Overflow => new OverflowException(),
#pragma warning disable CS0618 // ExecutionEngineException is obsolete
ExceptionIDs.IllegalInstruction => new ExecutionEngineException("Illegal instruction: Attempted to execute an instruction code not defined by the processor."),
ExceptionIDs.PrivilegedInstruction => new ExecutionEngineException("Privileged instruction: Attempted to execute an instruction code that cannot be executed in user mode."),
ExceptionIDs.InPageError => new ExecutionEngineException("In page error: Attempted to access a memory page that is not present, and the system is unable to load the page. For example, this exception might occur if a network connection is lost while running a program over a network."),
#pragma warning restore CS0618
_ => null
};
#endif
Expand Down Expand Up @@ -445,8 +450,11 @@ private enum HwExceptionCode : uint

STATUS_DATATYPE_MISALIGNMENT = 0x80000002u,
STATUS_ACCESS_VIOLATION = 0xC0000005u,
STATUS_IN_PAGE_ERROR = 0xC0000006u,
STATUS_ILLEGAL_INSTRUCTION = 0xC000001Du,
STATUS_INTEGER_DIVIDE_BY_ZERO = 0xC0000094u,
STATUS_INTEGER_OVERFLOW = 0xC0000095u,
STATUS_PRIVILEGED_INSTRUCTION = 0xC0000096u,
}
[StructLayout(LayoutKind.Explicit, Size = AsmOffsets.SIZEOF__PAL_LIMITED_CONTEXT)]
public struct PAL_LIMITED_CONTEXT
Expand Down Expand Up @@ -601,6 +609,18 @@ public static void RhThrowHwEx(uint exceptionCode, ref ExInfo exInfo)
exceptionId = ExceptionIDs.Overflow;
break;

case (uint)HwExceptionCode.STATUS_ILLEGAL_INSTRUCTION:
exceptionId = ExceptionIDs.IllegalInstruction;
break;

case (uint)HwExceptionCode.STATUS_IN_PAGE_ERROR:
exceptionId = ExceptionIDs.InPageError;
break;

case (uint)HwExceptionCode.STATUS_PRIVILEGED_INSTRUCTION:
exceptionId = ExceptionIDs.PrivilegedInstruction;
break;

default:
// We don't wrap SEH exceptions from foreign code like CLR does, so we believe that we
// know the complete set of HW faults generated by managed code and do not need to handle
Expand Down
3 changes: 3 additions & 0 deletions src/coreclr/nativeaot/Runtime.Base/src/System/Runtime/ExceptionIDs.cs
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Expand Up @@ -22,5 +22,8 @@ enum ExceptionIDs
DataMisaligned = 10,
EntrypointNotFound = 11,
AmbiguousImplementation = 12,
IllegalInstruction = 13,
PrivilegedInstruction = 14,
InPageError = 15,
}
}
3 changes: 3 additions & 0 deletions src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/ExceptionIDs.cs
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Expand Up @@ -17,5 +17,8 @@ internal enum ExceptionIDs
DataMisaligned = 10,
EntrypointNotFound = 11,
AmbiguousImplementation = 12,
IllegalInstruction = 13,
PrivilegedInstruction = 14,
InPageError = 15,
}
}
12 changes: 12 additions & 0 deletions src/coreclr/nativeaot/System.Private.CoreLib/src/System/RuntimeExceptionHelpers.cs
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Expand Up @@ -96,6 +96,18 @@ internal static class RuntimeExceptionHelpers
FailFast("Access Violation: Attempted to read or write protected memory. This is often an indication that other memory is corrupt. The application will be terminated since this platform does not support throwing an AccessViolationException.");
return null;

case ExceptionIDs.IllegalInstruction:
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I am not sure if we want to create an exception on the NativeAOT or behave like in the case of Access violation and just failfast here.

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I think PlarformNotSupportedException would be the best because it will allow us to have same behavior as CoreCLR for valid C#, but invalid use of hardware intrinsics.

For example:

using System.Runtime.Intrinsics;
using System.Runtime.Intrinsics.X86;

Sse41.Blend(Vector128<double>.One, default, default);

I'm not guarding this with Sse41.IsSupported and the generated code has an unguarded blendpd instruction. CoreCLR-JIT would generate a PNSE throw instead of the unguarded blendpd.

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I am not sure whether we want these faults to be catchable exceptions. The JIT assumes that these instructions won't throw, and it may take shortcuts when generating GC info for this IP. Catching and handling this fault would produce a GC hole.

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In coreclr, it is not catchable - the exception is created just for reporting the failure.

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I am not sure whether we want these faults to be catchable exceptions. The JIT assumes that these instructions won't throw, and it may take shortcuts when generating GC info for this IP. Catching and handling this fault would produce a GC hole.

👍

I think there's also a desire to differentiate between "the user called this API without checking, the JIT did the right thing" and "something in the JIT went wrong and an invalid instruction was emitted". In some cases it might even be invalid on all hardware, such as from a buggy encoding and not simply some encoding that would be valid on new enough hardware.

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In coreclr, it is not catchable - the exception is created just for reporting the failure.

The exceptions should not be catchable in native aot either. I think it should look more like the access violation handling. I have tried the following with this change on Native AOT (my machine does not have AvxVnni support):
dotnet publish /p:PublishAot=true /p:IlcInstructionSet=avx2

using System.Runtime.Intrinsics;
using System.Runtime.Intrinsics.X86;

Console.WriteLine(AvxVnni.IsSupported);

try
{
    AvxVnni.MultiplyWideningAndAdd(default(Vector128<int>), default(Vector128<byte>), default(Vector128<sbyte>)).ToString();
}
catch (Exception e)
{
    Console.WriteLine("HANDLED!");
}

It prints:

False
HANDLED!

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I've updated it to fail fast on NativeAOT like we do for the access violation.

FailFast("Illegal instruction: Attempted to execute an instruction code not defined by the processor.");
return null;

case ExceptionIDs.PrivilegedInstruction:
FailFast("Privileged instruction: Attempted to execute an instruction code that cannot be executed in user mode.");
return null;

case ExceptionIDs.InPageError:
FailFast("In page error: Attempted to access a memory page that is not present, and the system is unable to load the page. For example, this exception might occur if a network connection is lost while running a program over a network.");
return null;

case ExceptionIDs.DataMisaligned:
return new DataMisalignedException();

Expand Down