Add cDac contract for ResolveFrameHelper by leculver · Pull Request #129261 · dotnet/runtime

leculver · 2026-06-10T21:06:09Z

cDac does not support ResolveFrameHelper, leading to broken stacks/missed roots when it's on the callstack.

dotnet-policy-service · 2026-06-10T21:07:24Z

Tagging subscribers to this area: @steveisok, @tommcdon, @dotnet/dotnet-diag
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This PR extends the cDAC stack-walking contracts to understand ResolveHelperFrame (a resumable TransitionFrame used by interface resolve helper dispatch), so stack walking can correctly step past it and derive a correct thread context (including argument registers) from its TransitionBlock.

Changes:

Add a new cDAC data type/descriptor for ResolveHelperFrame (native descriptor + managed data adapter) and wire it into stack-walk frame classification/resumable handling.
Update platform frame handlers to support updating context from a raw TransitionBlock pointer and to update argument registers for ResolveHelperFrame where appropriate (AMD64/ARM64).
Extend unit test infrastructure and stack-walk tests to cover ResolveHelperFrame frame enumeration and AMD64 context reconstruction from the TransitionBlock.

Show a summary per file

File	Description
src/native/managed/cdac/tests/UnitTests/StackWalkTests.cs	Adds mock target/runtime-info setup and new tests covering `ResolveHelperFrame` enumeration + context update.
src/native/managed/cdac/tests/UnitTests/MockDescriptors/MockDescriptors.Frame.cs	Adds mock layouts/builders for `ResolveHelperFrame`, `TransitionBlock`, and minimal register sets.
src/native/managed/cdac/tests/TestInfrastructure/TestPlaceholderTarget.cs	Makes `TryGetThreadContext` return `false` so stack-walk can use its fallback path in tests.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/DataType.cs	Introduces `DataType.ResolveHelperFrame`.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/ResolveHelperFrame.cs	Adds managed cDAC data adapter for `ResolveHelperFrame.TransitionBlockPtr`.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/StackWalk_1.cs	Treats `ResolveHelperFrame` as resumable (`FRAME_ATTR_RESUMABLE`) in stack-walk state tracking.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/IPlatformFrameHandler.cs	Extends frame-handler interface with `HandleTransitionBlock` and `HandleResolveHelperFrame`.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/FrameHelpers.cs	Adds `ResolveHelperFrame` handling for context updates and return-address retrieval.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/BaseFrameHandler.cs	Factors common transition-block handling and adds helper for updating argument registers from the transition block.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARMFrameHandler.cs	Routes transition handling via `HandleTransitionBlock` and keeps ARM argument-register updates.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARM64FrameHandler.cs	Updates argument registers for `ResolveHelperFrame` after applying the transition block.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/AMD64FrameHandler.cs	Updates argument registers for `ResolveHelperFrame` after applying the transition block.
src/coreclr/vm/frames.h	Exposes `ResolveHelperFrame::m_pTransitionBlock` offset via `cdac_data<ResolveHelperFrame>`.
src/coreclr/vm/datadescriptor/datadescriptor.inc	Emits the native cDAC type descriptor for `ResolveHelperFrame` under `FEATURE_RESOLVE_HELPER_DISPATCH`.

Copilot's findings

Files reviewed: 14/14 changed files
Comments generated: 1

Copilot

Copilot's findings

Files reviewed: 15/15 changed files
Comments generated: 2

Copilot

Copilot's findings

Files reviewed: 15/15 changed files
Comments generated: 1

lateralusX

LGTM!

leculver · 2026-06-16T18:18:51Z

Helix arm64 runs have been timing out all day. Since this feature is primarily for arm64, we need tests to run here before merging, so I'm going to hold off merging temporarily and wait until helix arm64 runs are working.

Add ResolveHelperFrame to the cDAC descriptor and managed frame model so stack walking can classify it, recover return addresses, treat it as resumable, and restore transition-block context. Add unit coverage for classification and AMD64 context restoration, including argument registers. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Add the directly-read ResolveHelperFrame.TransitionBlockPtr field to the contract's descriptor table and describe its handling: it uses the TransitionFrame mechanism but additionally restores argument registers on all platforms, and is gated by FEATURE_RESOLVE_HELPER_DISPATCH. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

ARM64FrameHandler.HandleResolveHelperFrame (restoring argument registers from the TransitionBlock) was untested. Convert the AMD64-only fact into a theory covering X64 and Arm64: thread an explicit RuntimeInfoArchitecture through CreateTarget to select the platform handler, and parameterize the mock TransitionBlock register names so the Arm64 case restores x0/x19. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Copilot's findings

Files reviewed: 15/15 changed files
Comments generated: 1

jkotas · 2026-06-18T15:51:08Z

 | `SoftwareExceptionFrame` | `ReturnAddress` | Return address saved in Frame |
 | `FramedMethodFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock |
 | `FramedMethodFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
+| `ResolveHelperFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock (only present when `FEATURE_RESOLVE_HELPER_DISPATCH` is defined) |


This was test-only code for Native AOT. I do not think it is currently reachable.
Are you able to actually hit this in tests?

No, this is from code review only. I mostly want to make sure that we aren't missing a cDac contract for some scenario which would require servicing later. This seems to be the only coreclr!Frame that isn't wrapped. If this is pure test code that will never ship, I will close this PR. That wasn't obvious from source inspection.

Scanning through it looks like DOTNET_JitForceControlFlowGuard=1 can still reach this, and this code is dac-ized in the legacy dac. Seems like it would be safer to wrap it in case we need to debug something where it shows up.
I'm happy to close without merging if you disagree though.

I do not think it is reachable currently.
ResolveHelperFrame is only used by VSD_ResolveWorkerForInterfaceLookupSlot. VSD_ResolveWorkerForInterfaceLookupSlot is only called by JIT_InterfaceLookupForSlot. JIT_InterfaceLookupForSlot ID is CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT.CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT is never emitted by the JIT currently.
I think you can delete this whole chain if you would like.

Thanks! I'll close this one and open a new one to do exactly that.

leculver requested review from Copilot, max-charlamb and noahfalk June 10, 2026 21:06

leculver added the area-Diagnostics-cdac label Jun 10, 2026

Copilotstarted reviewing on behalf of leculver June 10, 2026 21:06 View session

CopilotAI reviewed Jun 10, 2026
View reviewed changes

Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/DataType.cs

This was referenced Jun 11, 2026
The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#3008
Open
[browser][coreCLR] Wasm.Console.Node.Sample - undefined symbol: SystemInteropJS_GetManagedStackTrace #129229
Closed

leculver force-pushed the leculver/cdac-resolve-helper-frame branch from adfd317 to 64b2076Compare June 11, 2026 11:55

CopilotAI review requested due to automatic review settings June 11, 2026 12:57

Copilotstarted reviewing on behalf of leculver June 11, 2026 12:57 View session

CopilotAI reviewed Jun 11, 2026
View reviewed changes

Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/DataType.cs
Comment thread...gnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARM64FrameHandler.cs

build-analysisBot mentioned this pull request Jun 11, 2026
slow macOS - "##[error]The job running on agent Azure Pipelines 9 ran longer than the maximum time of 60 minutes." dotnet/dnceng#1883
Open
3 tasks

CopilotAI review requested due to automatic review settings June 12, 2026 17:36

leculver force-pushed the leculver/cdac-resolve-helper-frame branch from d579395 to 01f9f71Compare June 12, 2026 17:36

Copilotstarted reviewing on behalf of leculver June 12, 2026 17:37 View session

CopilotAI reviewed Jun 12, 2026
View reviewed changes

Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/DataType.cs

This was referenced Jun 12, 2026
Multiple Helix work items fail on maccatalyst/tvos CoreCLR Release #126460
Closed
Arm/Arm64: Segfault in System.Security.Cryptography.Tests#129339
Closed

leculver force-pushed the leculver/cdac-resolve-helper-frame branch from 01f9f71 to b81ab89Compare June 15, 2026 13:50

build-analysisBot mentioned this pull request Jun 15, 2026
Android WebSocket failure #121518
Open

lateralusX approved these changes Jun 16, 2026
View reviewed changes

leculverand others added 5 commits June 16, 2026 14:19

Fix cDAC ResolveHelperFrame tests
9f19732
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Separate ResolveHelperFrame return address handling
b6c8c7a
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

CopilotAI review requested due to automatic review settings June 16, 2026 18:19

leculver force-pushed the leculver/cdac-resolve-helper-frame branch from b81ab89 to 2a8047eCompare June 16, 2026 18:19

leculver enabled auto-merge (squash) June 16, 2026 18:19

Copilotstarted reviewing on behalf of leculver June 16, 2026 18:19 View session

CopilotAI reviewed Jun 16, 2026
View reviewed changes

Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/DataType.cs

build-analysisBot mentioned this pull request Jun 18, 2026
[ci-scan] Test failure: cDAC stress test on Windows.11.Arm64.Open #129556
Closed

noahfalk approved these changes Jun 18, 2026
View reviewed changes

jkotas reviewed Jun 18, 2026
View reviewed changes

leculver closed this Jun 21, 2026

auto-merge was automatically disabled June 21, 2026 14:17
Pull request was closed

leculver deleted the leculver/cdac-resolve-helper-frame branch June 21, 2026 14:18

github-actionsBot locked and limited conversation to collaborators Jul 22, 2026

Uh oh!

Conversation

leculver commented Jun 10, 2026

Uh oh!

dotnet-policy-serviceBot commented Jun 10, 2026

Uh oh!

CopilotAI left a comment

Choose a reason for hiding this comment

Pull request overview

Copilot's findings

Uh oh!

Uh oh!

CopilotAI left a comment

Choose a reason for hiding this comment

Copilot's findings

Uh oh!

Uh oh!

Uh oh!

CopilotAI left a comment

Choose a reason for hiding this comment

Copilot's findings

Uh oh!

Uh oh!

lateralusX left a comment

Choose a reason for hiding this comment

Uh oh!

leculver commented Jun 16, 2026

Uh oh!

CopilotAI left a comment

Choose a reason for hiding this comment

Copilot's findings

Uh oh!

Uh oh!

jkotasJun 18, 2026

Choose a reason for hiding this comment

Uh oh!

leculverJun 18, 2026• edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

leculverJun 18, 2026

Choose a reason for hiding this comment

Uh oh!

jkotasJun 21, 2026

Choose a reason for hiding this comment

Uh oh!

leculverJun 21, 2026

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

leculverJun 18, 2026•
edited
Loading