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Add System.Diagnostics.StackFrame.GetMethodFromNativeIP API for VS4Mac #61289

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merged 6 commits into from
Nov 9, 2021
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Add System.Diagnostics.StackFrame.GetMethodFromNativeIP API for VS4Mac #61289

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6b7f5a0
Add System.Diagnostics.StackFrame.GetMethodInfoFromNativeIP API for V…
mikem8361 Nov 3, 2021
dbe2368
Code review feedback. Return MethodBase instead of MethodInfo. Rename…
mikem8361 Nov 7, 2021
9a14e5d
Fix Mono build break
mikem8361 Nov 7, 2021
b3a9a60
Better fix for Mono break
mikem8361 Nov 7, 2021
3aeaed6
Code review feedback
mikem8361 Nov 9, 2021
308f640
Remove unneccesary blank line
mikem8361 Nov 9, 2021
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23 changes: 23 additions & 0 deletions src/coreclr/System.Private.CoreLib/src/System/Diagnostics/StackFrame.CoreCLR.cs
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Expand Up @@ -2,6 +2,9 @@
// The .NET Foundation licenses this file to you under the MIT license.

using System.Text;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;

namespace System.Diagnostics
{
Expand Down Expand Up @@ -50,5 +53,25 @@ private void BuildStackFrame(int skipFrames, bool needFileInfo)
}

private static bool AppendStackFrameWithoutMethodBase(StringBuilder sb) => false;

[DllImport(RuntimeHelpers.QCall, EntryPoint = "StackFrame_GetMethodDescFromNativeIP")]
private static extern RuntimeMethodHandleInternal GetMethodDescFromNativeIP(IntPtr ip);

/// <summary>
/// Returns the MethodBase instance for the managed code IP address.
///
/// Warning: The implementation of this method has race for dynamic and collectible methods.
/// </summary>
/// <param name="ip">code address</param>
/// <returns>MethodBase instance for the method or null if IP not found</returns>
internal static MethodBase? GetMethodFromNativeIP(IntPtr ip)
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We should probably add a comment right here saying that the implementation of this method has known race conditions for unloadable code + MethodBase isn't a good design choice for working with NativeAOT, therefore don't make it public in the future without considering those issues. Reduces the chance we forget the history when we need a public API later.

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Or even better - create issue that tracks adding the public API and link it from here

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I added a TODO describing most of this here: https://github.com/mikem8361/runtime/blob/b3a9a6086dcef769b82a5750489738254b6aee80/src/coreclr/vm/debugdebugger.cpp#L788

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Is that good enough?

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I did add a comment to the method's header.

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I do think having the message that you added right here in the header is valuable. When people convert a private API to public nothing enforces that they will look at implementation code in a separate file. The comment you added calls out the race condition but doesn't mention the design issue for using MethodBase in NativeAOT. As @jkotas suggested filing an issue and linking to that is an improvement over my original suggestion.

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I'm going to use issue #61186 to detail these limitations and to propose the new 7.0 API.

{
RuntimeMethodHandleInternal method = GetMethodDescFromNativeIP(ip);

if (method.Value == IntPtr.Zero)
return null;

return RuntimeType.GetMethodBase(null, method);
}
}
}
23 changes: 22 additions & 1 deletion src/coreclr/vm/debugdebugger.cpp
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Expand Up @@ -297,7 +297,6 @@ FCIMPL0(FC_BOOL_RET, DebugDebugger::IsLogging)
}
FCIMPLEND


FCIMPL4(void, DebugStackTrace::GetStackFramesInternal,
StackFrameHelper* pStackFrameHelperUNSAFE,
INT32 iSkip,
Expand Down Expand Up @@ -778,6 +777,28 @@ FCIMPL4(void, DebugStackTrace::GetStackFramesInternal,
}
FCIMPLEND

extern MethodDesc* QCALLTYPE StackFrame_GetMethodDescFromNativeIP(LPVOID ip)
{
QCALL_CONTRACT;

MethodDesc* pResult = nullptr;

BEGIN_QCALL;

// TODO: There is a race for dynamic and collectible methods here between getting
// the MethodDesc here and when the managed wrapper converts it into a MethodBase
// where the method could be collected.
EECodeInfo codeInfo((PCODE)ip);
if (codeInfo.IsValid())
{
pResult = codeInfo.GetMethodDesc();
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}

END_QCALL;

return pResult;
}

FORCEINLINE void HolderDestroyStrongHandle(OBJECTHANDLE h) { if (h != NULL) DestroyStrongHandle(h); }
typedef Wrapper<OBJECTHANDLE, DoNothing<OBJECTHANDLE>, HolderDestroyStrongHandle, NULL> StrongHandleHolder;

Expand Down
2 changes: 2 additions & 0 deletions src/coreclr/vm/debugdebugger.h
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Expand Up @@ -171,4 +171,6 @@ class DebugStackTrace

};

extern "C" MethodDesc* QCALLTYPE StackFrame_GetMethodDescFromNativeIP(LPVOID ip);

#endif // __DEBUG_DEBUGGER_h__
1 change: 1 addition & 0 deletions src/coreclr/vm/qcallentrypoints.cpp
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Expand Up @@ -115,6 +115,7 @@ static const Entry s_QCall[] =
DllImportEntry(RuntimeModule_GetType)
DllImportEntry(RuntimeModule_GetScopeName)
DllImportEntry(RuntimeModule_GetFullyQualifiedName)
DllImportEntry(StackFrame_GetMethodDescFromNativeIP)
DllImportEntry(ModuleBuilder_GetStringConstant)
DllImportEntry(ModuleBuilder_GetTypeRef)
DllImportEntry(ModuleBuilder_GetTokenFromTypeSpec)
Expand Down
4 changes: 4 additions & 0 deletions src/libraries/System.Private.CoreLib/src/ILLink/ILLink.Descriptors.LibraryBuild.xml
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Expand Up @@ -4,5 +4,9 @@
<!-- Internal API used by tests only. -->
<method name="GetICUVersion" />
</type>
<type fullname="System.Diagnostics.StackFrame">
<!-- Used by VS4Mac via reflection to symbolize stack traces -->
<method name="GetMethodFromNativeIP" />
</type>
</assembly>
</linker>