[cDAC] Implement GCCover portion of SOSDacImpl::GetMethodDescData

docs/design/datacontracts/CodeVersions.md

@@ -40,6 +40,9 @@ public virtual bool CodeVersionManagerSupportsMethod(TargetPointer methodDesc);
 
 // Return the instruction pointer corresponding to the start of the given native code version
 public virtual TargetCodePointer GetNativeCode(NativeCodeVersionHandle codeVersionHandle);
+
+// Gets the GCStressCodeCopy pointer if available, otherwise returns TargetPointer.Null
+public virtual TargetPointer GetGCStressCodeCopy(NativeCodeVersionHandle codeVersionHandle);
 ```
 ### Extension Methods
 ```csharp
@@ -61,13 +64,15 @@ Data descriptors used:
 | NativeCodeVersionNode | NativeCode | indicates an explicit native code version node |
 | NativeCodeVersionNode | Flags | `NativeCodeVersionNodeFlags` flags, see below |
 | NativeCodeVersionNode | VersionId | Version ID corresponding to the parent IL code version |
+| NativeCodeVersionNode | GCCoverageInfo | GCStress debug info, if supported |
 | ILCodeVersioningState | FirstVersionNode | pointer to the first `ILCodeVersionNode` |
 | ILCodeVersioningState | ActiveVersionKind | an `ILCodeVersionKind` value indicating which fields of the active version are value |
 | ILCodeVersioningState | ActiveVersionNode | if the active version is explicit, the NativeCodeVersionNode for the active version |
 | ILCodeVersioningState | ActiveVersionModule | if the active version is synthetic or unknown, the pointer to the Module that defines the method |
 | ILCodeVersioningState | ActiveVersionMethodDef | if the active version is synthetic or unknown, the MethodDef token for the method |
 | ILCodeVersionNode | VersionId | Version ID of the node |
 | ILCodeVersionNode | Next | Pointer to the next `ILCodeVersionNode`|
+| GCCoverageInfo | SavedCode | Pointer to the GCCover saved code copy, if supported |
 
 The flag indicates that the default version of the code for a method desc is active:
 ```csharp
@@ -249,3 +254,11 @@ bool ICodeVersions.CodeVersionManagerSupportsMethod(TargetPointer methodDescAddr
     return true;
 }
 ```
+
+### Finding GCStress Code Copy
+```csharp
+public virtual TargetPointer GetGCStressCodeCopy(NativeCodeVersionHandle codeVersionHandle);
+```
+
+1. If `codeVersionHandle` is synthetic, use the `IRuntimeTypeSystem` to find the GCStressCodeCopy.
+2. If `codeVersionHandle` is explicit, read the `NativeCodeVersionNode` for the `GCCoverageInfo` pointer. This value is nullable as it only exists in some builds. If the value doesn't exist or is a nullptr, return `TargetPointer.Null`. Otherwise return the `SavedCode` pointer from the `GCCoverageInfo` struct.

docs/design/datacontracts/RuntimeTypeSystem.md

@@ -159,6 +159,8 @@ partial interface IRuntimeTypeSystem : IContract
     // Get an instruction pointer that can be called to cause the MethodDesc to be executed
     public virtual TargetCodePointer GetNativeCode(MethodDescHandle methodDesc);
 
+    // Gets the GCStressCodeCopy pointer if available, otherwise returns TargetPointer.Null
+    public virtual TargetPointer GetGCStressCodeCopy(MethodDescHandle methodDesc);
 }
 ```
 
@@ -638,6 +640,7 @@ We depend on the following data descriptors:
 | `MethodDesc` | `Slot` | The method's slot |
 | `MethodDesc` | `Flags` | The method's flags |
 | `MethodDesc` | `Flags3AndTokenRemainder` | More flags for the method, and the low bits of the method's token's RID |
+| `MethodDesc` | `GCCoverageInfo` | The method's GCCover debug info, if supported |
 | `MethodDescCodeData` | `VersioningState` | The IL versioning state associated with a method descriptor
 | `MethodDescChunk` | `MethodTable` | The method table set of methods belongs to |
 | `MethodDescChunk` | `Next` | The next chunk of methods |
@@ -654,6 +657,7 @@ We depend on the following data descriptors:
 | `StoredSigMethodDesc` | `cSig` | Count of bytes in the metadata signature |
 | `StoredSigMethodDesc` | `ExtendedFlags` | Flags field for the `StoredSigMethodDesc` |
 | `DynamicMethodDesc` | `MethodName` | Pointer to Null-terminated UTF8 string describing the Method desc |
+| `GCCoverageInfo` | `SavedCode` | Pointer to the GCCover saved code copy, if supported |
 
 
 The contract depends on the following other contracts

src/coreclr/debug/runtimeinfo/datadescriptor.cpp

@@ -13,6 +13,10 @@
 #include "methodtable.h"
 #include "threads.h"
 
+#ifdef HAVE_GCCOVER
+#include "gccover.h"
+#endif // HAVE_GCCOVER
+
 // begin blob definition
 
 extern "C"

src/coreclr/debug/runtimeinfo/datadescriptor.h

@@ -331,6 +331,9 @@ CDAC_TYPE_FIELD(MethodDesc, /*uint16*/, Flags, cdac_data<MethodDesc>::Flags)
 CDAC_TYPE_FIELD(MethodDesc, /*uint16*/, Flags3AndTokenRemainder, cdac_data<MethodDesc>::Flags3AndTokenRemainder)
 CDAC_TYPE_FIELD(MethodDesc, /*uint8*/, EntryPointFlags, cdac_data<MethodDesc>::EntryPointFlags)
 CDAC_TYPE_FIELD(MethodDesc, /*pointer*/, CodeData, cdac_data<MethodDesc>::CodeData)
+#ifdef HAVE_GCCOVER
+CDAC_TYPE_FIELD(MethodDesc, /*pointer*/, GCCoverageInfo, offsetof(MethodDesc, m_GcCover))
+#endif // HAVE_GCCOVER
 CDAC_TYPE_END(MethodDesc)
 
 CDAC_TYPE_BEGIN(MethodDescChunk)
@@ -522,6 +525,9 @@ CDAC_TYPE_FIELD(NativeCodeVersionNode, /*pointer*/, MethodDesc, cdac_data<Native
 CDAC_TYPE_FIELD(NativeCodeVersionNode, /*pointer*/, NativeCode, cdac_data<NativeCodeVersionNode>::NativeCode)
 CDAC_TYPE_FIELD(NativeCodeVersionNode, /*uint32*/, Flags, cdac_data<NativeCodeVersionNode>::Flags)
 CDAC_TYPE_FIELD(NativeCodeVersionNode, /*nuint*/, ILVersionId, cdac_data<NativeCodeVersionNode>::ILVersionId)
+#ifdef HAVE_GCCOVER
+CDAC_TYPE_FIELD(NativeCodeVersionNode, /*pointer*/, GCCoverageInfo, cdac_data<NativeCodeVersionNode>::GCCoverageInfo)
+#endif // HAVE_GCCOVER
 CDAC_TYPE_END(NativeCodeVersionNode)
 
 CDAC_TYPE_BEGIN(ILCodeVersionNode)
@@ -535,6 +541,13 @@ CDAC_TYPE_BEGIN(ProfControlBlock)
 CDAC_TYPE_FIELD(ProfControlBlock, /*uint64*/, GlobalEventMask, offsetof(ProfControlBlock, globalEventMask))
 CDAC_TYPE_END(ProfControlBlock)
 
+#ifdef HAVE_GCCOVER
+CDAC_TYPE_BEGIN(GCCoverageInfo)
+CDAC_TYPE_INDETERMINATE(GCCoverageInfo)
+CDAC_TYPE_FIELD(GCCoverageInfo, /*pointer*/, SavedCode, offsetof(GCCoverageInfo, savedCode))
+CDAC_TYPE_END(GCCoverageInfo)
+#endif // HAVE_GCCOVER
+
 CDAC_TYPES_END()
 
 CDAC_GLOBALS_BEGIN()

src/coreclr/vm/codeversion.h

@@ -330,6 +330,9 @@ struct cdac_data<NativeCodeVersionNode>
     static constexpr size_t NativeCode = offsetof(NativeCodeVersionNode, m_pNativeCode);
     static constexpr size_t Flags = offsetof(NativeCodeVersionNode, m_flags);
     static constexpr size_t ILVersionId = offsetof(NativeCodeVersionNode, m_parentId);
+#ifdef HAVE_GCCOVER
+    static constexpr size_t GCCoverageInfo = offsetof(NativeCodeVersionNode, m_gcCover);
+#endif // HAVE_GCCOVER
 };
 
 class NativeCodeVersionCollection

src/native/managed/cdacreader/Microsoft.Diagnostics.DataContractReader.Abstractions/ContractRegistry.cs

@@ -58,5 +58,5 @@ internal abstract class ContractRegistry
     /// <summary>
     /// Gets an instance of the ReJIT contract for the target.
     /// </summary>
-    public abstract IReJIT ReJIT { get;  }
+    public abstract IReJIT ReJIT { get; }
 }

src/native/managed/cdacreader/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/ICodeVersions.cs

@@ -22,6 +22,8 @@ internal interface ICodeVersions : IContract
 
     public virtual TargetCodePointer GetNativeCode(NativeCodeVersionHandle codeVersionHandle) => throw new NotImplementedException();
 
+    public virtual TargetPointer GetGCStressCodeCopy(NativeCodeVersionHandle codeVersionHandle) => throw new NotImplementedException();
+
     public virtual bool CodeVersionManagerSupportsMethod(TargetPointer methodDesc) => throw new NotImplementedException();
 }
 

src/native/managed/cdacreader/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs

@@ -166,6 +166,8 @@ internal interface IRuntimeTypeSystem : IContract
     public virtual bool HasNativeCodeSlot(MethodDescHandle methodDesc) => throw new NotImplementedException();
 
     public virtual TargetPointer GetAddressOfNativeCodeSlot(MethodDescHandle methodDesc) => throw new NotImplementedException();
+
+    public virtual TargetPointer GetGCStressCodeCopy(MethodDescHandle methodDesc) => throw new NotImplementedException();
     #endregion MethodDesc inspection APIs
 }
 

src/native/managed/cdacreader/Microsoft.Diagnostics.DataContractReader.Abstractions/DataType.cs

@@ -76,4 +76,5 @@ public enum DataType
     NonVtableSlot,
     MethodImpl,
     NativeCodeSlot,
+    GCCoverageInfo,
 }

src/native/managed/cdacreader/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/CodeVersions_1.cs

@@ -183,6 +183,30 @@ NativeCodeVersionHandle ICodeVersions.GetActiveNativeCodeVersionForILCodeVersion
         });
     }
 
+    TargetPointer ICodeVersions.GetGCStressCodeCopy(NativeCodeVersionHandle codeVersionHandle)
+    {
+        Debug.Assert(codeVersionHandle.Valid);
+
+        if (!codeVersionHandle.IsExplicit)
+        {
+            // NativeCodeVersion::GetGCCoverageInfo
+            IRuntimeTypeSystem rts = _target.Contracts.RuntimeTypeSystem;
+            MethodDescHandle md = rts.GetMethodDescHandle(codeVersionHandle.MethodDescAddress);
+            return rts.GetGCStressCodeCopy(md);
+        }
+        else
+        {
+            // NativeCodeVersionNode::GetGCCoverageInfo
+            NativeCodeVersionNode codeVersionNode = AsNode(codeVersionHandle);
+            if (codeVersionNode.GCCoverageInfo is TargetPointer gcCoverageInfoAddr && gcCoverageInfoAddr != TargetPointer.Null)
+            {
+                Target.TypeInfo gcCoverageInfoType = _target.GetTypeInfo(DataType.GCCoverageInfo);
+                return gcCoverageInfoAddr + (ulong)gcCoverageInfoType.Fields["SavedCode"].Offset;
+            }
+            return TargetPointer.Null;
+        }
+    }
+
     [Flags]
     internal enum MethodDescVersioningStateFlags : byte
     {

src/native/managed/cdacreader/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs

@@ -141,6 +141,9 @@ private static uint ComputeToken(Target target, Data.MethodDesc desc, Data.Metho
         public bool IsUnboxingStub => HasFlags(MethodDescFlags_1.MethodDescFlags3.IsUnboxingStub);
 
         public TargetPointer CodeData => _desc.CodeData;
+
+        public TargetPointer? GCCoverageInfo => _desc.GCCoverageInfo;
+
         public bool IsIL => Classification == MethodClassification.IL || Classification == MethodClassification.Instantiated;
 
         internal bool HasNonVtableSlot => MethodDescOptionalSlots.HasNonVtableSlot(_desc.Flags);
@@ -1012,6 +1015,17 @@ private TargetCodePointer GetMethodEntryPointIfExists(MethodDesc md)
         return _target.ReadCodePointer(addrOfSlot);
     }
 
+    TargetPointer IRuntimeTypeSystem.GetGCStressCodeCopy(MethodDescHandle methodDesc)
+    {
+        MethodDesc md = _methodDescs[methodDesc.Address];
+        if (md.GCCoverageInfo is TargetPointer gcCoverageInfoAddr && gcCoverageInfoAddr != TargetPointer.Null)
+        {
+            Target.TypeInfo gcCoverageInfoType = _target.GetTypeInfo(DataType.GCCoverageInfo);
+            return gcCoverageInfoAddr + (ulong)gcCoverageInfoType.Fields["SavedCode"].Offset;
+        }
+        return TargetPointer.Null;
+    }
+
     private class NonValidatedMethodTableQueries : MethodValidation.IMethodTableQueries
     {
         private readonly RuntimeTypeSystem_1 _rts;

src/native/managed/cdacreader/Microsoft.Diagnostics.DataContractReader.Contracts/Data/MethodDesc.cs

@@ -18,6 +18,10 @@ public MethodDesc(Target target, TargetPointer address)
         Flags3AndTokenRemainder = target.Read<ushort>(address + (ulong)type.Fields[nameof(Flags3AndTokenRemainder)].Offset);
         EntryPointFlags = target.Read<byte>(address + (ulong)type.Fields[nameof(EntryPointFlags)].Offset);
         CodeData = target.ReadPointer(address + (ulong)type.Fields[nameof(CodeData)].Offset);
+        if (type.Fields.ContainsKey(nameof(GCCoverageInfo)))
+        {
+            GCCoverageInfo = target.ReadPointer(address + (ulong)type.Fields[nameof(GCCoverageInfo)].Offset);
+        }
     }
 
     public byte ChunkIndex { get; init; }
@@ -26,7 +30,9 @@ public MethodDesc(Target target, TargetPointer address)
     public ushort Flags3AndTokenRemainder { get; init; }
     public byte EntryPointFlags { get; init; }
 
-    public TargetPointer CodeData { get; set; }
+    public TargetPointer CodeData { get; init; }
+
+    public TargetPointer? GCCoverageInfo { get; init; }
 }
 
 internal sealed class InstantiatedMethodDesc : IData<InstantiatedMethodDesc>

src/native/managed/cdacreader/Microsoft.Diagnostics.DataContractReader.Contracts/Data/NativeCodeVersionNode.cs

@@ -17,12 +17,18 @@ public NativeCodeVersionNode(Target target, TargetPointer address)
         NativeCode = target.ReadCodePointer(address + (ulong)type.Fields[nameof(NativeCode)].Offset);
         Flags = target.Read<uint>(address + (ulong)type.Fields[nameof(Flags)].Offset);
         ILVersionId = target.ReadNUInt(address + (ulong)type.Fields[nameof(ILVersionId)].Offset);
+        if (type.Fields.ContainsKey(nameof(GCCoverageInfo)))
+        {
+            GCCoverageInfo = target.ReadPointer(address + (ulong)type.Fields[nameof(GCCoverageInfo)].Offset);
+        }
     }
 
     public TargetPointer Next { get; init; }
     public TargetPointer MethodDesc { get; init; }
 
     public TargetCodePointer NativeCode { get; init; }
-    public uint Flags{ get; init; }
+    public uint Flags { get; init; }
     public TargetNUInt ILVersionId { get; init; }
+
+    public TargetPointer? GCCoverageInfo { get; init; }
 }

src/native/managed/cdacreader/src/Legacy/SOSDacImpl.cs

@@ -349,16 +349,14 @@ int ISOSDacInterface.GetMethodDescData(ulong methodDesc, ulong ip, DacpMethodDes
                 }
             }
 
-#if false // TODO[cdac]: HAVE_GCCOVER
+            // HAVE_GCCOVER
             if (requestedNativeCodeVersion.Valid)
             {
-                TargetPointer gcCoverAddr = nativeCodeContract.GetGCCoverageInfo(requestedNativeCodeVersion);
-                if (gcCoverAddr != TargetPointer.Null)
-                {
-                    throw new NotImplementedException(); // TODO[cdac]: gc stress code copy
-                }
+                // TargetPointer.Null if GCCover information is not available.
+                // In certain minidumps, we won't save the GCCover information.
+                // (it would be unwise to do so, it is heavy and not a customer scenario).
+                data->GCStressCodeCopy = nativeCodeContract.GetGCStressCodeCopy(requestedNativeCodeVersion);
             }
-#endif
 
             if (data->bIsDynamic != 0)
             {

src/native/managed/cdacreader/tests/CodeVersionsTests.cs

@@ -254,6 +254,24 @@ internal static Target CreateTarget(
         return target;
     }
 
+    internal static Target CreateTarget(
+        MockTarget.Architecture arch,
+        MockCodeVersions builder,
+        Mock<IRuntimeTypeSystem> mockRuntimeTypeSystem)
+    {
+        TestPlaceholderTarget target = new TestPlaceholderTarget(
+            arch,
+            builder.Builder.GetReadContext().ReadFromTarget,
+            builder.Types);
+
+        IContractFactory<ICodeVersions> cvfactory = new CodeVersionsFactory();
+        ContractRegistry reg = Mock.Of<ContractRegistry>(
+            c => c.CodeVersions == cvfactory.CreateContract(target, 1)
+                && c.RuntimeTypeSystem == mockRuntimeTypeSystem.Object);
+        target.SetContracts(reg);
+        return target;
+    }
+
     [Theory]
     [ClassData(typeof(MockTarget.StdArch))]
     public void GetNativeCodeVersion_Null(MockTarget.Architecture arch)
@@ -678,4 +696,65 @@ public void IlToNativeToIlCodeVersion_SyntheticAndExplicit(MockTarget.Architectu
         NativeCodeVersionHandle syntheticNativeCodeVersion = codeVersions.GetActiveNativeCodeVersionForILCodeVersion(methodDescAddress, syntheticILcodeVersion);
         Assert.True(syntheticILcodeVersion.Equals(codeVersions.GetILCodeVersion(syntheticNativeCodeVersion)));
     }
+
+    private void GetGCStressCodeCopy_Impl(MockTarget.Architecture arch, bool returnsNull)
+    {
+        MockCodeVersions builder = new(arch);
+        Mock<IRuntimeTypeSystem> mockRTS = new();
+
+        // Setup synthetic NativeCodeVersion
+        TargetPointer expectedSyntheticCodeCopyAddr = returnsNull ? TargetPointer.Null : new(0x2345_6789);
+        TargetPointer syntheticMethodDescAddr = new(0x2345_8000);
+        NativeCodeVersionHandle syntheticHandle = NativeCodeVersionHandle.CreateSynthetic(syntheticMethodDescAddr);
+        MethodDescHandle methodDescHandle = new MethodDescHandle(syntheticMethodDescAddr);
+        mockRTS.Setup(rts => rts.GetMethodDescHandle(syntheticMethodDescAddr)).Returns(methodDescHandle);
+        mockRTS.Setup(rts => rts.GetGCStressCodeCopy(methodDescHandle)).Returns(expectedSyntheticCodeCopyAddr);
+
+        // Setup explicit NativeCodeVersion
+        TargetPointer? explicitGCCoverageInfoAddr = returnsNull ? TargetPointer.Null : new(0x1234_5678);
+        TargetPointer nativeCodeVersionNode = builder.AddNativeCodeVersionNode();
+        builder.FillNativeCodeVersionNode(
+            nativeCodeVersionNode,
+            methodDesc: TargetPointer.Null,
+            nativeCode: TargetCodePointer.Null,
+            next: TargetPointer.Null,
+            isActive: true,
+            ilVersionId: new(1),
+            gcCoverageInfo: explicitGCCoverageInfoAddr);
+        NativeCodeVersionHandle explicitHandle = NativeCodeVersionHandle.CreateExplicit(nativeCodeVersionNode);
+
+        var target = CreateTarget(arch, builder, mockRTS);
+        var codeVersions = target.Contracts.CodeVersions;
+
+        // TEST
+        TargetPointer actualSyntheticCodeCopyAddr = codeVersions.GetGCStressCodeCopy(syntheticHandle);
+        Assert.Equal(expectedSyntheticCodeCopyAddr, actualSyntheticCodeCopyAddr);
+
+        if(returnsNull)
+        {
+            TargetPointer actualExplicitCodeCopyAddr = codeVersions.GetGCStressCodeCopy(explicitHandle);
+            Assert.Equal(TargetPointer.Null, actualExplicitCodeCopyAddr);
+        }
+        else
+        {
+            Target.TypeInfo gcCoverageInfoType = target.GetTypeInfo(DataType.GCCoverageInfo);
+            TargetPointer expectedExplicitCodeCopyAddr = explicitGCCoverageInfoAddr.Value + (ulong)gcCoverageInfoType.Fields["SavedCode"].Offset;
+            TargetPointer actualExplicitCodeCopyAddr = codeVersions.GetGCStressCodeCopy(explicitHandle);
+            Assert.Equal(expectedExplicitCodeCopyAddr, actualExplicitCodeCopyAddr);
+        }
+    }
+
+    [Theory]
+    [ClassData(typeof(MockTarget.StdArch))]
+    public void GetGCStressCodeCopy_Null(MockTarget.Architecture arch)
+    {
+        GetGCStressCodeCopy_Impl(arch, returnsNull: true);
+    }
+
+    [Theory]
+    [ClassData(typeof(MockTarget.StdArch))]
+    public void GetGCStressCodeCopy_NotNull(MockTarget.Architecture arch)
+    {
+        GetGCStressCodeCopy_Impl(arch, returnsNull: false);
+    }
 }

src/native/managed/cdacreader/tests/MethodDescTests.cs

@@ -69,6 +69,8 @@ public void MethodDescGetMethodDescTokenOk(MockTarget.Architecture arch)
         Assert.False(isCollectible);
         TargetPointer versioning = rts.GetMethodDescVersioningState(handle);
         Assert.Equal(TargetPointer.Null, versioning);
+        TargetPointer gcStressCodeCopy = rts.GetGCStressCodeCopy(handle);
+        Assert.Equal(TargetPointer.Null, gcStressCodeCopy);
     }
 
     public static IEnumerable<object[]> StdArchOptionalSlotsData()