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Implement GetIlCodeAndSig DacDbi API in cDAC (#128354)
Port the `GetILCodeAndSig` DacDbi entry point from the native DAC to the managed cDAC, returning the target-address/size of a method's IL and its local-variable signature token. --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: rcj1 <77995559+rcj1@users.noreply.github.com> Co-authored-by: rcj1 <rachel.jarvi@gmail.com>
1 parent c7bd259 commit 2790c60

4 files changed

Lines changed: 103 additions & 6 deletions

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‎src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/CorDbHResults.cs‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -10,6 +10,7 @@ public static class CorDbgHResults
1010
public const int CORDBG_E_READVIRTUAL_FAILURE = unchecked((int)0x80131c49);
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public const int ERROR_BUFFER_OVERFLOW = unchecked((int)0x8007006F); // HRESULT_FROM_WIN32(ERROR_BUFFER_OVERFLOW)
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public const int CORDBG_E_CLASS_NOT_LOADED = unchecked((int)0x80131303);
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public const int CORDBG_E_FUNCTION_NOT_IL = unchecked((int)0x8013130a);
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public const int CORDBG_E_TARGET_INCONSISTENT = unchecked((int)0x80131c36);
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public const int CORDBG_S_NOT_ALL_BITS_SET = unchecked((int)0x00131c13);
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public const int CORDBG_E_NON_MATCHING_CONTEXT = unchecked((int)0x80131327);

‎src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/EcmaMetadataUtils.cs‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -22,6 +22,7 @@ public enum TokenType : uint
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mdtTypeDef = 0x02 << 24,
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mdtFieldDef = 0x04 << 24,
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mdtMethodDef = 0x06 << 24,
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mdtSignature = 0x11 << 24,
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}
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public const uint TokenTypeMask = 0xff000000;

‎src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs‎

Lines changed: 67 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,6 +7,7 @@
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using System.Collections.Immutable;
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using System.Diagnostics;
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using System.Linq;
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using System.Reflection;
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using System.Reflection.Metadata;
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using System.Reflection.Metadata.Ecma335;
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using System.Numerics;
@@ -1693,7 +1694,72 @@ public int ResolveExactGenericArgsToken(uint dwExactGenericArgsTokenIndex, ulong
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}
16941695

16951696
public int GetILCodeAndSig(ulong vmAssembly, uint functionToken, DacDbiTargetBuffer* pTargetBuffer, uint* pLocalSigToken)
1696-
=> LegacyFallbackHelper.CanFallback() && _legacy is not null ? _legacy.GetILCodeAndSig(vmAssembly, functionToken, pTargetBuffer, pLocalSigToken) : HResults.E_NOTIMPL;
1697+
{
1698+
int hr = HResults.S_OK;
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try
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{
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*pTargetBuffer = default;
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*pLocalSigToken = (uint)EcmaMetadataUtils.TokenType.mdtSignature;
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ILoader loader = _target.Contracts.Loader;
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Contracts.ModuleHandle moduleHandle = loader.GetModuleHandleFromAssemblyPtr(new TargetPointer(vmAssembly));
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MetadataReader mdReader = _target.Contracts.EcmaMetadata.GetMetadata(moduleHandle)
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?? throw new InvalidOperationException("Module has no metadata.");
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MethodDefinitionHandle mdMethodHandle = MetadataTokens.MethodDefinitionHandle((int)EcmaMetadataUtils.GetRowId(functionToken));
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MethodDefinition methodDef = mdReader.GetMethodDefinition(mdMethodHandle);
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// Reject anything whose metadata CodeType isn't IL.
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if ((methodDef.ImplAttributes & MethodImplAttributes.CodeTypeMask) != MethodImplAttributes.IL)
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throw Marshal.GetExceptionForHR(CorDbgHResults.CORDBG_E_FUNCTION_NOT_IL)!;
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ModuleLookupTables lookupTables = loader.GetLookupTables(moduleHandle);
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TargetPointer methodDescPtr = loader.GetModuleLookupMapElement(lookupTables.MethodDefToDesc, functionToken, out _);
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if (methodDescPtr != TargetPointer.Null)
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{
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IRuntimeTypeSystem rts = _target.Contracts.RuntimeTypeSystem;
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MethodDescHandle mdHandle = rts.GetMethodDescHandle(methodDescPtr);
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if (!rts.IsIL(mdHandle))
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throw Marshal.GetExceptionForHR(CorDbgHResults.CORDBG_E_FUNCTION_NOT_IL)!;
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}
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else if (methodDef.RelativeVirtualAddress == 0)
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throw Marshal.GetExceptionForHR(CorDbgHResults.CORDBG_E_FUNCTION_NOT_IL)!;
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TargetPointer headerPtr = loader.GetILHeader(moduleHandle, functionToken);
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if (headerPtr != TargetPointer.Null)
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{
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int headerSize = HeaderReaderHelpers.GetHeaderSize(_target, headerPtr);
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int codeSize = HeaderReaderHelpers.GetCodeSize(_target, headerPtr);
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if (HeaderReaderHelpers.TryGetLocalVarSigToken(_target, headerPtr, out int localToken) && localToken != 0)
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{
1735+
*pLocalSigToken = (uint)localToken;
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}
1737+
1738+
pTargetBuffer->pAddress = headerPtr.Value + (ulong)headerSize;
1739+
pTargetBuffer->cbSize = (uint)codeSize;
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}
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}
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catch (System.Exception ex)
1743+
{
1744+
hr = ex.HResult;
1745+
}
1746+
#if DEBUG
1747+
if (_legacy is not null)
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{
1749+
DacDbiTargetBuffer bufferLocal = default;
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uint sigLocal;
1751+
int hrLocal = _legacy.GetILCodeAndSig(vmAssembly, functionToken, &bufferLocal, &sigLocal);
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Debug.ValidateHResult(hr, hrLocal);
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if (hr == HResults.S_OK)
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{
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Debug.Assert(pTargetBuffer->pAddress == bufferLocal.pAddress, $"cDAC ILAddr: 0x{pTargetBuffer->pAddress:X}, DAC ILAddr: 0x{bufferLocal.pAddress:X}");
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Debug.Assert(pTargetBuffer->cbSize == bufferLocal.cbSize, $"cDAC ILSize: {pTargetBuffer->cbSize}, DAC ILSize: {bufferLocal.cbSize}");
1757+
Debug.Assert(*pLocalSigToken == sigLocal, $"cDAC LocalSig: 0x{*pLocalSigToken:X}, DAC LocalSig: 0x{sigLocal:X}");
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}
1759+
}
1760+
#endif
1761+
return hr;
1762+
}
16971763

16981764
public int GetNativeCodeInfo(ulong vmAssembly, uint functionToken, nint pJitManagerList)
16991765
=> LegacyFallbackHelper.CanFallback() && _legacy is not null ? _legacy.GetNativeCodeInfo(vmAssembly, functionToken, pJitManagerList) : HResults.E_NOTIMPL;

‎src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/HeaderReaderHelpers.cs‎

Lines changed: 34 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1,26 +1,55 @@
11
// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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4+
using System;
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using System.Runtime.InteropServices;
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67
namespace Microsoft.Diagnostics.DataContractReader.Legacy;
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89
internal enum CorILMethodFlags
910
{
10-
CorILMethod_FormatShift = 3,
11-
CorILMethod_FormatMask = (1 << CorILMethod_FormatShift) - 1,
11+
CorILMethod_TinyFormatMask = 0x3,
12+
CorILMethod_FatFormatMask = 0x7,
1213
CorILMethod_TinyFormat = 0x0002,
1314
CorILMethod_FatFormat = 0x0003,
1415
}
1516
internal static class HeaderReaderHelpers
1617
{
18+
// See ECMA-335 II.25.4.1
19+
private static bool IsTiny(byte firstByte)
20+
=> (firstByte & (int)CorILMethodFlags.CorILMethod_TinyFormatMask) == (int)CorILMethodFlags.CorILMethod_TinyFormat;
21+
22+
private static bool IsFat(byte firstByte)
23+
=> (firstByte & (int)CorILMethodFlags.CorILMethod_FatFormatMask) == (int)CorILMethodFlags.CorILMethod_FatFormat;
24+
25+
public static int GetHeaderSize(Target target, TargetPointer ilHeader)
26+
{
27+
// see ECMA-335 II.25.4
28+
byte firstByte = target.Read<byte>(ilHeader);
29+
if (IsTiny(firstByte))
30+
return 1;
31+
if (IsFat(firstByte))
32+
return 12;
33+
throw new BadImageFormatException("Invalid IL method header.");
34+
}
35+
36+
public static int GetCodeSize(Target target, TargetPointer ilHeader)
37+
{
38+
// see ECMA-335 II.25.4
39+
byte firstByte = target.Read<byte>(ilHeader);
40+
if (IsTiny(firstByte))
41+
return firstByte >> 2;
42+
if (IsFat(firstByte))
43+
return (int)target.Read<uint>(ilHeader + 4);
44+
throw new BadImageFormatException("Invalid IL method header.");
45+
}
46+
1747
public static bool TryGetLocalVarSigToken(Target target, TargetPointer ilHeader, out int localVarSigToken)
1848
{
1949
// see ECMA-335 II.25.4
2050
localVarSigToken = 0;
21-
ushort sizeAndFlags = target.Read<ushort>(ilHeader); // get flags and size of il header
22-
CorILMethodFlags flags = (CorILMethodFlags)(sizeAndFlags & (int)CorILMethodFlags.CorILMethod_FormatMask);
23-
if (flags != CorILMethodFlags.CorILMethod_FatFormat)
51+
byte firstByte = target.Read<byte>(ilHeader);
52+
if (!IsFat(firstByte))
2453
return false;
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2655
localVarSigToken = target.Read<int>(ilHeader + 8);

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