Adding GetAssemblyLoadContext cDAC API (#117939)

rcj1 · web-flow · commit 2db9fdf5b408 · 2025-07-28T18:39:50.000-07:00
* adding GetAssemblyLoadContext cDAC API

* simplifying field access

* restructuring etc

* comments
diff --git a/docs/design/datacontracts/Loader.md b/docs/design/datacontracts/Loader.md
@@ -68,6 +68,7 @@ string GetPath(ModuleHandle handle);
 string GetFileName(ModuleHandle handle);
 TargetPointer GetLoaderAllocator(ModuleHandle handle);
 TargetPointer GetILBase(ModuleHandle handle);
+TargetPointer GetAssemblyLoadContext(ModuleHandle handle);
 ModuleLookupTables GetLookupTables(ModuleHandle handle);
 TargetPointer GetModuleLookupMapElement(TargetPointer table, uint token, out TargetNUInt flags);
 bool IsCollectible(ModuleHandle handle);
@@ -107,6 +108,8 @@ TargetPointer GetStubHeap(TargetPointer loaderAllocatorPointer);
 | `Assembly` | `NotifyFlags` | Flags relating to the debugger/profiler notification state of the assembly |
 | `Assembly` | `Level` | File load level of the assembly |
 | `PEAssembly` | `PEImage` | Pointer to the PEAssembly's PEImage |
+| `PEAssembly` | `AssemblyBinder` | Pointer to the PEAssembly's binder |
+| `AssemblyBinder` | `ManagedAssemblyLoadContext` | Pointer to the AssemblyBinder's ManagedAssemblyLoadContext |
 | `PEImage` | `LoadedImageLayout` | Pointer to the PEImage's loaded PEImageLayout |
 | `PEImage` | `ProbeExtensionResult` | PEImage's ProbeExtensionResult |
 | `ProbeExtensionResult` | `Type` | Type of ProbeExtensionResult |
@@ -384,6 +387,14 @@ TargetPointer GetILBase(ModuleHandle handle)
     return target.ReadPointer(handle.Address + /* Module::Base offset */);
 }
 
+TargetPointer ILoader.GetAssemblyLoadContext(ModuleHandle handle)
+{
+    PEAssembly peAssembly = target.ReadPointer(handle.Address + /* Module::PEAssembly offset */);
+    AssemblyBinder binder = target.ReadPointer(peAssembly + /* PEAssembly::AssemblyBinder offset */);
+    ObjectHandle objectHandle = new ObjectHandle(binder);
+    return objectHandle.Object;
+}
+
 ModuleLookupTables GetLookupTables(ModuleHandle handle)
 {
     return new ModuleLookupTables(
diff --git a/docs/design/datacontracts/Thread.md b/docs/design/datacontracts/Thread.md
@@ -46,7 +46,6 @@ record struct ThreadData (
 ThreadStoreData GetThreadStoreData();
 ThreadStoreCounts GetThreadCounts();
 ThreadData GetThreadData(TargetPointer threadPointer);
-TargetPointer GetManagedThreadObject(TargetPointer threadPointer);
 ```
 
 ## Version 1
@@ -128,10 +127,4 @@ ThreadData GetThreadData(TargetPointer address)
         NextThread: target.ReadPointer(address + /* Thread::LinkNext offset */) - threadLinkOffset;
     );
 }
-
-TargetPointer GetManagedThreadObject(TargetPointer threadPointer)
-{
-    var runtimeThread = new Thread(Target, threadPointer);
-    return Contracts.GCHandle.GetObject(new DacGCHandle(runtimeThread.m_ExposedObject));
-}
 ```
diff --git a/src/coreclr/debug/runtimeinfo/datadescriptor.inc b/src/coreclr/debug/runtimeinfo/datadescriptor.inc
@@ -266,8 +266,14 @@ CDAC_TYPE_END(LoaderAllocator)
 CDAC_TYPE_BEGIN(PEAssembly)
 CDAC_TYPE_INDETERMINATE(PEAssembly)
 CDAC_TYPE_FIELD(PEAssembly, /*pointer*/, PEImage, cdac_data<PEAssembly>::PEImage)
+CDAC_TYPE_FIELD(PEAssembly, /*pointer*/, AssemblyBinder, cdac_data<PEAssembly>::AssemblyBinder)
 CDAC_TYPE_END(PEAssembly)
 
+CDAC_TYPE_BEGIN(AssemblyBinder)
+CDAC_TYPE_INDETERMINATE(AssemblyBinder)
+CDAC_TYPE_FIELD(AssemblyBinder, /*pointer*/, ManagedAssemblyLoadContext, cdac_data<AssemblyBinder>::ManagedAssemblyLoadContext)
+CDAC_TYPE_END(AssemblyBinder)
+
 CDAC_TYPE_BEGIN(PEImage)
 CDAC_TYPE_INDETERMINATE(PEImage)
 CDAC_TYPE_FIELD(PEImage, /*pointer*/, LoadedImageLayout, cdac_data<PEImage>::LoadedImageLayout)
diff --git a/src/coreclr/vm/assembly.cpp b/src/coreclr/vm/assembly.cpp
@@ -431,10 +431,7 @@ Assembly *Assembly::CreateDynamic(AssemblyBinder* pBinder, NativeAssemblyNamePar
         IfFailThrow(pAssemblyEmit->DefineAssembly(pAssemblyNameParts->_pPublicKeyOrToken, pAssemblyNameParts->_cbPublicKeyOrToken, hashAlgorithm,
                                                    pAssemblyNameParts->_pName, &assemData, pAssemblyNameParts->_flags,
                                                    &ma));
-        pPEAssembly = PEAssembly::Create(pAssemblyEmit);
-
-        // Set it as the fallback load context binder for the dynamic assembly being created
-        pPEAssembly->SetFallbackBinder(pBinder);
+        pPEAssembly = PEAssembly::Create(pAssemblyEmit, pBinder);
     }
 
     AppDomain* pDomain = ::GetAppDomain();
diff --git a/src/coreclr/vm/assemblybinder.h b/src/coreclr/vm/assemblybinder.h
@@ -128,6 +128,12 @@ class AssemblyBinder
     INT_PTR m_ptrManagedAssemblyLoadContext;
 
     SArray<Assembly*> m_loadedAssemblies;
+    friend struct cdac_data<AssemblyBinder>;
 };
 
+template<>
+struct cdac_data<AssemblyBinder>
+{
+    static constexpr size_t ManagedAssemblyLoadContext = offsetof(AssemblyBinder, m_ptrManagedAssemblyLoadContext);
+};
 #endif
diff --git a/src/coreclr/vm/peassembly.cpp b/src/coreclr/vm/peassembly.cpp
@@ -647,6 +647,7 @@ PEAssembly::PEAssembly(
                 BINDER_SPACE::Assembly* pBindResultInfo,
                 IMetaDataEmit* pEmit,
                 BOOL isSystem,
+                AssemblyBinder* pFallbackBinder /*= NULL*/,
                 PEImage * pPEImage /*= NULL*/,
                 BINDER_SPACE::Assembly * pHostAssembly /*= NULL*/)
 {
@@ -670,7 +671,7 @@ PEAssembly::PEAssembly(
     m_refCount = 1;
     m_isSystem = isSystem;
     m_pHostAssembly = nullptr;
-    m_pFallbackBinder = nullptr;
+    m_pAssemblyBinder = nullptr;
 
     pPEImage = pBindResultInfo ? pBindResultInfo->GetPEImage() : pPEImage;
     if (pPEImage)
@@ -722,6 +723,15 @@ PEAssembly::PEAssembly(
         m_pHostAssembly = pBindResultInfo;
     }
 
+    if (m_pHostAssembly != nullptr)
+    {
+        m_pAssemblyBinder = m_pHostAssembly->GetBinder();
+    }
+    else
+    {
+        m_pAssemblyBinder = pFallbackBinder;
+    }
+
 #ifdef LOGGING
     GetPathOrCodeBase(m_debugName);
     m_pDebugName = m_debugName.GetUTF8();
@@ -740,6 +750,7 @@ PEAssembly *PEAssembly::Open(
         nullptr,        // BindResult
         nullptr,        // IMetaDataEmit
         FALSE,          // isSystem
+        nullptr,        // FallbackBinder
         pPEImageIL,
         pHostAssembly);
 
@@ -833,7 +844,7 @@ PEAssembly* PEAssembly::Open(BINDER_SPACE::Assembly* pBindResult)
 };
 
 /* static */
-PEAssembly *PEAssembly::Create(IMetaDataAssemblyEmit *pAssemblyEmit)
+PEAssembly *PEAssembly::Create(IMetaDataAssemblyEmit *pAssemblyEmit, AssemblyBinder *pFallbackBinder)
 {
     CONTRACT(PEAssembly *)
     {
@@ -847,7 +858,7 @@ PEAssembly *PEAssembly::Create(IMetaDataAssemblyEmit *pAssemblyEmit)
     // we have.)
     SafeComHolder<IMetaDataEmit> pEmit;
     pAssemblyEmit->QueryInterface(IID_IMetaDataEmit, (void **)&pEmit);
-    RETURN new PEAssembly(NULL, pEmit, FALSE);
+    RETURN new PEAssembly(NULL, pEmit, FALSE, pFallbackBinder);
 }
 
 #endif // #ifndef DACCESS_COMPILE
@@ -1083,25 +1094,5 @@ TADDR PEAssembly::GetMDInternalRWAddress()
 // Returns the AssemblyBinder* instance associated with the PEAssembly
 PTR_AssemblyBinder PEAssembly::GetAssemblyBinder()
 {
-    LIMITED_METHOD_CONTRACT;
-
-    PTR_AssemblyBinder pBinder = NULL;
-
-    PTR_BINDER_SPACE_Assembly pHostAssembly = GetHostAssembly();
-    if (pHostAssembly)
-    {
-        pBinder = pHostAssembly->GetBinder();
-    }
-    else
-    {
-        // If we do not have a host assembly, check if we are dealing with
-        // a dynamically emitted assembly and if so, use its fallback load context
-        // binder reference.
-        if (IsReflectionEmit())
-        {
-            pBinder = GetFallbackBinder();
-        }
-    }
-
-    return pBinder;
+    return m_pAssemblyBinder;
 }
diff --git a/src/coreclr/vm/peassembly.h b/src/coreclr/vm/peassembly.h
@@ -312,20 +312,18 @@ class PEAssembly final
     // For Dynamic assemblies this is the fallback binder.
     PTR_AssemblyBinder GetAssemblyBinder();
 
-#ifndef DACCESS_COMPILE
-    void SetFallbackBinder(PTR_AssemblyBinder pFallbackBinder)
-    {
-        LIMITED_METHOD_CONTRACT;
-        m_pFallbackBinder = pFallbackBinder;
-    }
-
-#endif //!DACCESS_COMPILE
-
+    // For certain assemblies, we do not have m_pHostAssembly since they are not bound using an actual binder.
+    // An example is Ref-Emitted assemblies. Thus, when such assemblies trigger load of their dependencies,
+    // we need to ensure they are loaded in appropriate load context.
+    //
+    // To enable this, we maintain a concept of "FallbackBinder", which will be set to the Binder of the
+    // assembly that created the dynamic assembly. If the creator assembly is dynamic itself, then its fallback
+    // load context would be propagated to the assembly being dynamically generated.
     PTR_AssemblyBinder GetFallbackBinder()
     {
         LIMITED_METHOD_CONTRACT;
 
-        return m_pFallbackBinder;
+        return (m_pHostAssembly != NULL) ? NULL : m_pAssemblyBinder;
     }
 
     // ------------------------------------------------------------
@@ -341,7 +339,7 @@ class PEAssembly final
 
     static PEAssembly* Open(BINDER_SPACE::Assembly* pBindResult);
 
-    static PEAssembly* Create(IMetaDataAssemblyEmit* pEmit);
+    static PEAssembly* Create(IMetaDataAssemblyEmit* pEmit, AssemblyBinder* pFallbackBinder);
 
       // ------------------------------------------------------------
       // Utility functions
@@ -372,6 +370,7 @@ class PEAssembly final
         BINDER_SPACE::Assembly* pBindResultInfo,
         IMetaDataEmit* pEmit,
         BOOL isSystem,
+        AssemblyBinder* pFallbackBinder = NULL,
         PEImage* pPEImageIL = NULL,
         BINDER_SPACE::Assembly* pHostAssembly = NULL
     );
@@ -425,15 +424,7 @@ class PEAssembly final
     bool                     m_isSystem;
 
     PTR_BINDER_SPACE_Assembly m_pHostAssembly;
-
-    // For certain assemblies, we do not have m_pHostAssembly since they are not bound using an actual binder.
-    // An example is Ref-Emitted assemblies. Thus, when such assemblies trigger load of their dependencies,
-    // we need to ensure they are loaded in appropriate load context.
-    //
-    // To enable this, we maintain a concept of "FallbackBinder", which will be set to the Binder of the
-    // assembly that created the dynamic assembly. If the creator assembly is dynamic itself, then its fallback
-    // load context would be propagated to the assembly being dynamically generated.
-    PTR_AssemblyBinder m_pFallbackBinder;
+    PTR_AssemblyBinder m_pAssemblyBinder;
 
     friend struct cdac_data<PEAssembly>;
 };  // class PEAssembly
@@ -442,6 +433,7 @@ template<>
 struct cdac_data<PEAssembly>
 {
     static constexpr size_t PEImage = offsetof(PEAssembly, m_PEImage);
+    static constexpr size_t AssemblyBinder = offsetof(PEAssembly, m_pAssemblyBinder);
 };
 
 typedef ReleaseHolder<PEAssembly> PEAssemblyHolder;
diff --git a/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/ILoader.cs b/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/ILoader.cs
@@ -91,6 +91,7 @@ public interface ILoader : IContract
     string GetFileName(ModuleHandle handle) => throw new NotImplementedException();
     TargetPointer GetLoaderAllocator(ModuleHandle handle) => throw new NotImplementedException();
     TargetPointer GetILBase(ModuleHandle handle) => throw new NotImplementedException();
+    TargetPointer GetAssemblyLoadContext(ModuleHandle handle) => throw new NotImplementedException();
     ModuleLookupTables GetLookupTables(ModuleHandle handle) => throw new NotImplementedException();
     TargetPointer GetModuleLookupMapElement(TargetPointer table, uint token, out TargetNUInt flags) => throw new NotImplementedException();
     bool IsCollectible(ModuleHandle handle) => throw new NotImplementedException();
diff --git a/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/DataType.cs b/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/DataType.cs
@@ -35,6 +35,7 @@ public enum DataType
     Assembly,
     LoaderAllocator,
     PEAssembly,
+    AssemblyBinder,
     PEImage,
     PEImageLayout,
     CGrowableSymbolStream,
diff --git a/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs b/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs
@@ -306,6 +306,15 @@ TargetPointer ILoader.GetILBase(ModuleHandle handle)
         return module.Base;
     }
 
+    TargetPointer ILoader.GetAssemblyLoadContext(ModuleHandle handle)
+    {
+        Data.Module module = _target.ProcessedData.GetOrAdd<Data.Module>(handle.Address);
+        Data.PEAssembly peAssembly = _target.ProcessedData.GetOrAdd<Data.PEAssembly>(module.PEAssembly);
+        Data.AssemblyBinder binder = _target.ProcessedData.GetOrAdd<Data.AssemblyBinder>(peAssembly.AssemblyBinder);
+        Data.ObjectHandle objectHandle = _target.ProcessedData.GetOrAdd<Data.ObjectHandle>(binder.ManagedAssemblyLoadContext);
+        return objectHandle.Object;
+    }
+
     ModuleLookupTables ILoader.GetLookupTables(ModuleHandle handle)
     {
         Data.Module module = _target.ProcessedData.GetOrAdd<Data.Module>(handle.Address);
diff --git a/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/AssemblyBinder.cs b/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/AssemblyBinder.cs
@@ -0,0 +1,17 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+
+namespace Microsoft.Diagnostics.DataContractReader.Data;
+
+internal sealed class AssemblyBinder : IData<AssemblyBinder>
+{
+    static AssemblyBinder IData<AssemblyBinder>.Create(Target target, TargetPointer address) => new AssemblyBinder(target, address);
+    public AssemblyBinder(Target target, TargetPointer address)
+    {
+        Target.TypeInfo type = target.GetTypeInfo(DataType.AssemblyBinder);
+        ManagedAssemblyLoadContext = target.ReadPointer(address + (ulong)type.Fields[nameof(ManagedAssemblyLoadContext)].Offset);
+    }
+    public TargetPointer ManagedAssemblyLoadContext { get; init; }
+}
diff --git a/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEAssembly.cs b/src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/PEAssembly.cs
@@ -13,7 +13,9 @@ public PEAssembly(Target target, TargetPointer address)
         Target.TypeInfo type = target.GetTypeInfo(DataType.PEAssembly);
 
         PEImage = target.ReadPointer(address + (ulong)type.Fields[nameof(PEImage)].Offset);
+        AssemblyBinder = target.ReadPointer(address + (ulong)type.Fields[nameof(AssemblyBinder)].Offset);
     }
 
     public TargetPointer PEImage { get; init; }
+    public TargetPointer AssemblyBinder { get; init; }
 }
diff --git a/src/native/managed/cdac/mscordaccore_universal/Legacy/SOSDacImpl.cs b/src/native/managed/cdac/mscordaccore_universal/Legacy/SOSDacImpl.cs
@@ -2284,7 +2284,40 @@ int ISOSDacInterface8.GetFinalizationFillPointersSvr(ClrDataAddress heapAddr, ui
         => _legacyImpl8 is not null ? _legacyImpl8.GetFinalizationFillPointersSvr(heapAddr, cFillPointers, pFinalizationFillPointers, pNeeded) : HResults.E_NOTIMPL;
 
     int ISOSDacInterface8.GetAssemblyLoadContext(ClrDataAddress methodTable, ClrDataAddress* assemblyLoadContext)
-        => _legacyImpl8 is not null ? _legacyImpl8.GetAssemblyLoadContext(methodTable, assemblyLoadContext) : HResults.E_NOTIMPL;
+    {
+        int hr = HResults.S_OK;
+        try
+        {
+            if (methodTable == 0 || assemblyLoadContext == null)
+                hr = HResults.E_INVALIDARG;
+            else
+            {
+                Contracts.IRuntimeTypeSystem rtsContract = _target.Contracts.RuntimeTypeSystem;
+                Contracts.ILoader loaderContract = _target.Contracts.Loader;
+                Contracts.TypeHandle methodTableHandle = rtsContract.GetTypeHandle(methodTable.ToTargetPointer(_target));
+                Contracts.ModuleHandle moduleHandle = loaderContract.GetModuleHandleFromModulePtr(rtsContract.GetModule(methodTableHandle));
+                TargetPointer alc = loaderContract.GetAssemblyLoadContext(moduleHandle);
+                *assemblyLoadContext = alc.ToClrDataAddress(_target);
+            }
+        }
+        catch (System.Exception ex)
+        {
+            hr = ex.HResult;
+        }
+#if DEBUG
+        if (_legacyImpl8 is not null)
+        {
+            ClrDataAddress assemblyLoadContextLocal;
+            int hrLocal = _legacyImpl8.GetAssemblyLoadContext(methodTable, &assemblyLoadContextLocal);
+            Debug.Assert(hrLocal == hr, $"cDAC: {hr:x}, DAC: {hrLocal:x}");
+            if (hr == HResults.S_OK)
+            {
+                Debug.Assert(*assemblyLoadContext == assemblyLoadContextLocal);
+            }
+        }
+#endif
+        return hr;
+    }
     #endregion ISOSDacInterface8
 
     #region ISOSDacInterface9
