VS4Mac needs a runtime API to symbolize managed IPs

[mikem8361]

Background and motivation

VS4Mac needs a way to symbolize managed IPs when rethrowing a native NSException from Objective C++. They do the symbolizing in the telemetry upload on the unhandled NSException crash. They don't currently build a StackTrace/StackFrames when the managed NSException wrapper is thrown so all they need currently is a way to convert a IP address of a managed method into a full method name string.

This is a short term API needed for the next 6.0 service release discoverable only through reflection.

API Proposal

namespace  System.Diagnostics
{
    public class StackFrame
    {
         /// <summary>
        /// Returns the method info instance for the managed code IP address.
        /// </summary>
        /// <param name="ip">code address</param>
        /// <returns>MethodBase instance or null if IP not found</returns>
        internal static MethodBase? GetMethodFromNativeIP(IntPtr ip);
    }
}

API Usage

Type stackFrameType = typeof(System.Diagnostics.StackFrame);
MethodInfo? getMethodFromNativeIP = stackFrameType.GetMethod("GetMethodFromNativeIP", BindingFlags.NonPublic | BindingFlags.Static);
if (getMethodFromNativeIP is null)
{
    Console.WriteLine("GetMethodFromNativeIP not found");
    return;
}

long ip = 0;
MethodBase? testFunction = getMethodFromNativeIP.Invoke(null, new object[] { new IntPtr(ip) }) as MethodBase;
if (testFunction is null)
{
    Console.WriteLine("Test function not found");
    return;
}

Alternative Designs

For .NET 7.0, we could replace this temporary API with this public one:

public class StackFrame
{
    public static StackFrame? CreateFromNativeIP(IntPtr nativeIP, bool needFileInfo = false); 
}

Risks

The .NET 6.0 API has the following limitations that will need to be addressed:

1. There is a race condition for dynamic and collectable methods between when the MethodDesc is found and where it is wrapped in the MethodBase.
2. MethodBase isn't a good design choice for working with NativeAOT.

[dotnet-issue-labeler]

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[ghost]

Tagging subscribers to this area: @tommcdon
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Issue Details

---

Background and motivation

VS4Mac needs a way to symbolize managed IPs when rethrowing the NSException from Objective C++.

API Proposal

namespace  System.Runtime.CompilerServices.
{
    public static partial class RuntimeHelpers
    {
         /// <summary>
        /// Returns the method info instance for the managed code IP address.
        /// </summary>
        /// <param name="ip">code address</param>
        /// <returns>MethodInfo instance or null if IP not found</returns>
        internal static MethodInfo? GetMethodInfoFromIP(IntPtr ip);
    }
}

API Usage

TBD

Alternative Designs

No response

Risks

No response

Author:	mikem8361
Assignees:	mikem8361
Labels:	area-Diagnostics-coreclr
Milestone:	6.0.x

[jkotas]

Do you mean for this to become a public API in .NET 7?

I think it should be under System.Diagnostics namespace somewhere. Maybe a static factory method on StackFrame?

public class StackFrame
{
    public static StackFrame? CreateFromNativeIP(IntPtr nativeIP, bool needFileInfo = false); 
}

StackFrame will give you access to all other diagnostic information for the given IP: relative offset within the method, optional filenames, etc.

[jkotas]

Also, why is not System.Diagnostics.StackTrace enough? Note that there is StackTrace constructor that takes Exception.

[jkotas]

There is an existing API StackFrameExtensions.GetNativeIP. So this one should be called GetMethodInfoFromNativeIP to make the naming consistent.

[mikem8361]

I included you on a thread that should have more background/context. This issue is a WIP and isn't fleshed out.

[tommcdon]

No active requests for this feature, closing