.NET Core Profiler Crashing on 32 bit Application Environment

[Durai-cpp]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Hi Team,

I have developed a custom .NET Core profiler using Visual Studio 2019. To load the profiler, I’ve configured the environment variables in the web.config file as follows:

<environmentVariable name="CORECLR_ENABLE_PROFILING" value="1" />
<environmentVariable name="CORECLR_PROFILER" value="{cf0d821e-299b-5307-a3d8-b283c03916dd}" />
<environmentVariable name="CORECLR_PROFILER_PATH_64" value="C:\apps\Publish_3.0\Publish_3.0\ClrProfiler.dll" />
<environmentVariable name="CORECLR_PROFILER_PATH_32" value="C:\apps\Publish_3.0\Publish_3.0\ClrProfiler32.dll" />

With this setup, I'm able to successfully profile a 64-bit .NET Core application hosted in IIS.

However, when attempting to profile a 32-bit .NET Core application, I encounter the following error:
[aspnetcorev2_inprocess.dll] Event Log:
'Application '/LM/W3SVC/5/ROOT' with physical root 'E:\netcoreapp\bin\Release\netcoreapp3.1\publish' hit unexpected managed exception, exception code = '0xe0434352'.
First 30KB characters of captured stdout and stderr logs:

Unhandled exception. System.BadImageFormatException: Bad binary signature. (0x80131192)
at net_core_azure.Program.Main(String[] args)
End Event Log Message.
To troubleshoot, I enabled debug logs in the profiler. The issue appears to originate from the following block of code in
il_writer.cpp, at line 636:

HRESULT ILRewriter::SetILFunctionBody(unsigned size, LPBYTE pBody)
{
    if (m_pICorProfilerFunctionControl != nullptr) 
    {
        // We're supplying IL for a ReJIT scenario
        IfFailRet(m_pICorProfilerFunctionControl->SetILFunctionBody(size, pBody));
    } 
    else 
    {
        // Classic instrumentation during the first JIT compilation
        // Issue appears to be with the following line (line 636)
        IfFailRet(m_pICorProfilerInfo->SetILFunctionBody(m_moduleId, m_tkMethod, pBody));
    }
}

Additional Information:
The helper assembly is built with .NET Standard 2.0.
Both 32-bit and 64-bit VC++ Redistributables are installed on the machine.
Followed this URL to develop my custom profiler,
https://github.com/microsoftarchive/clrprofiler/blob/master/ILRewrite/ILRewriteProfiler/ilrewriter.cpp
Already raised questions in the following URL,
https://learn.microsoft.com/en-us/answers/questions/785908/net-core-profiler-crashing-on-32-bit-application-e
Request:
Could you please help identify why the 32-bit application fails when using the profiler, particularly at SetILFunctionBody()? Are there known issues or how to fix this issue ?

Thank you,

Expected Behavior

Our expectation is that the profiler should support both 32-bit and 64-bit applications.

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version

Helperassembly file builds with .NET standard 2.0

Anything else?

No response

[gfoidl]

I’ve configured the environment variables in the web.config file as follows:

Where are they?

Did nothing in https://learn.microsoft.com/en-us/answers/questions/785908/net-core-profiler-crashing-on-32-bit-application-e help?
With the information provided here it's hard to make this issue actionable, as too much details are missing.

Our expectation is that the profiler should support both 32-bit and 64-bit applications.

Why? The bitness of the process should match (different pointer sizes, different memory management, etc.).

[martincostello]

Our expectation is that the profiler should support both 32-bit and 64-bit applications.

The bitness of the process should match (different pointer sizes, different memory management, etc.).

This is a fundamental point here - while your profiler code may support 32-bit and 64-bit, you'll need to compile a separate binary for each bitness as you can't load a 32-bit binary into a 64-bit process and vice-versa.

The BadImageFormatException exception here implies that you're trying to load a 64-bit binary into a 32-bit process.

[Durai-cpp]

@martincostello Thank you for your response. I have separate binaries for both 64-bit and 32-bit architectures. When I run a 64-bit application, the 64-bit profiler DLL loads successfully and is able to instrument the application. However, the issue occurs when I run a 32-bit application. Although the 32-bit profiler binaries are loaded, the application fails at the following line: IfFailRet(m_pICorProfilerInfo->SetILFunctionBody(m_moduleId, m_tkMethod, pBody));

[Durai-cpp]

@gfoidl Thank you for your response. I believe the question is now clear and easy to understand.

[BrennanConroy]

E:\netcoreapp\bin\Release\netcoreapp3.1\publish

For starters, you should use a supported version: https://dotnet.microsoft.com/platform/support/policy

Also, this issue should probably be in the dotnet/runtime repo.

[Durai-cpp]

@BrennanConroy Thank you for your information. This issue raised in the dotnet/runtime repo: dotnet/runtime#117969