') + ')', 'gi'); if (regex.test(text)) { found = true; var frag = document.createDocumentFragment(); var parts = text.split(regex); parts.forEach(function(part, i) { if (i % 2 === 0) { frag.appendChild(document.createTextNode(part)); } else { var span = document.createElement('span'); span.className = 'userscript-highlight'; span.textContent = part; frag.appendChild(span); } }); node.parentNode.replaceChild(frag, node); } }); } else if (node.nodeType === 1 && node.childNodes) { // element var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT']; if (!skipTags.includes(node.tagName)) { Array.from(node.childNodes).forEach(highlight); } } } highlight(document.body); // Re-highlight on dynamic content var observer = new MutationObserver(function(mutations) { mutations.forEach(function(m) { m.addedNodes.forEach(function(node) { if (node.nodeType === 1 || node.nodeType === 3) highlight(node); }); }); }); observer.observe(document.body, { childList: true, subtree: true }); })(); } } catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + ', 'i'); if (__m === '*' || __re.test(location.href)) { // Strip utm_, fbclid, gclid, etc. from all links on page (function() { var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content', 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid', 'ref', 'ref_src', 'source', 'medium', 'campaign']; function cleanUrl(url) { try { var u = new URL(url, window.location.origin); var changed = false; trackingParams.forEach(function(p) { if (u.searchParams.has(p)) { u.searchParams.delete(p); changed = true; } }); return changed ? u.toString() : url; } catch (e) { return url; } } function cleanLinks() { document.querySelectorAll('a[href]').forEach(function(a) { var clean = cleanUrl(a.href); if (clean !== a.href) a.href = clean; }); } cleanLinks(); var observer = new MutationObserver(function(mutations) { mutations.forEach(function(m) { m.addedNodes.forEach(function(node) { if (node.nodeType === 1) { if (node.tagName === 'A') cleanLinks(); node.querySelectorAll('a[href]').forEach(function(a) { var clean = cleanUrl(a.href); if (clean !== a.href) a.href = clean; }); } }); }); }); observer.observe(document.body, { childList: true, subtree: true }); })(); } } catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); } })(); (function(){ try { var __m = "youtube.com"; var __re = new RegExp('^' + "youtube\\.com" + ', 'i'); if (__m === '*' || __re.test(location.href)) { // Auto-enable theater mode on YouTube (function() { function tryTheater() { var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]'); if (btn && !btn.classList.contains('activated')) { btn.click(); } } // Try immediately tryTheater(); // Try after navigation (SPA) var lastUrl = location.href; setInterval(function() { if (location.href !== lastUrl) { lastUrl = location.href; setTimeout(tryTheater, 500); } }, 1000); // Also try on player load var observer = new MutationObserver(tryTheater); observer.observe(document.body, { childList: true, subtree: true }); })(); } } catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); } })(); (function(){ try { var __m = "*"; var __re = new RegExp('^' + ".*" + ', 'i'); if (__m === '*' || __re.test(location.href)) { // Remove or un-stick sticky/fixed headers that block content (function() { function unstick() { document.querySelectorAll('header, nav, [role="banner"], .header, .navbar, .sticky, .fixed-top, [style*="position: fixed"], [style*="position:sticky"]').forEach(function(el) { if (el.style.position === 'fixed' || el.style.position === 'sticky' || getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') { el.style.position = 'static'; el.style.top = 'auto'; el.style.zIndex = 'auto'; } }); } unstick(); var observer = new MutationObserver(unstick); observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] }); })(); } } catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); } })(); })(); Fix ARM64 ThreadAbort issue by janvorli · Pull Request #120552 · dotnet/runtime · GitHub
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Fix ARM64 ThreadAbort issue - #120552

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janvorli merged 1 commit into
dotnet:mainfrom
janvorli:remove-eh-context-xstate
Oct 9, 2025
Merged

Fix ARM64 ThreadAbort issue#120552
janvorli merged 1 commit into
dotnet:mainfrom
janvorli:remove-eh-context-xstate

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@janvorlijanvorli commented Oct 8, 2025

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There is a problem with RtlRestoreContext not restoring context during thread abort if that abort comes from injected APC callback on ARM64 and the processor supports SVE. In that case, the context provided by the APC callback can contain XSTATE and when we start walking stack from that context, we copy that context into the REGDISPLAY. The problem is that we copy the ContextFlags without changes, so if they contained CONTEXT_XSTATE flag, it is kept set even though the REGDISPLAY has only plain old CONTEXT without any XSTATE.
When we call RtlRestoreContext in the ResumeAfterCatch, it fails because the XSTATE is not valid and so it returns. That's unexpected and we end up crashing with an assert.

The fix clears the CONTEXT_XSTATE in ResumableFrame::UpdateRegDisplay so that the REGDISPLAY's contexts ContextFlags are validly representing the context stored in the REGDISPLAY.

Close#120437

@janvorli
Fix ARM64 ThreadAbort issue
ad78d2b
There is a problem with RtlRestoreContext not restoring context during
ThreadAbort if that abort comes from injected APC callback on ARM64 and
the processor supports SVE. In that case, the context provided by the
APC callback can contain XSTATE and when we start walking stack from
that context, we copy that context into the REGDISPLAY. The problem is
that we copy the ContextFlags without changes, so if they contained
CONTEXT_XSTATE flag, it is kept set even though the REGDISPLAY has only
plain old CONTEXT without any xstate.
When we call RtlRestoreContext in the ResumeAfterCatch, it fails because
the XSTATE is not valid and so it returns. That's unexpected and we end
up crashing with an assert.
The fix clears the CONTEXT_XSTATE in ResumableFrame::UpdateRegDisplay so
that the REGDISPLAY ContextFlags are validly representing the context.
Closedotnet#120437
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janvorli requested a review from jkotasOctober 8, 2025 22:29
@janvorlijanvorli self-assigned this Oct 8, 2025
CopilotAI review requested due to automatic review settings October 8, 2025 22:29
@janvorlijanvorli added the area-ExceptionHandling-coreclr only use for closed issues label Oct 8, 2025
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Pull Request Overview

This PR fixes a ThreadAbort issue on ARM64 processors with SVE support where RtlRestoreContext fails during thread abort recovery. The issue occurs when an APC callback provides a context with XSTATE flags that are copied to a REGDISPLAY without the corresponding XSTATE data, causing RtlRestoreContext to fail.

  • Clears invalid CONTEXT_XSTATE flags in ResumableFrame::UpdateRegDisplay_Impl for both ARM64 and AMD64
  • Adds UNREACHABLE() marker after RtlRestoreContext call to indicate expected control flow
  • Ensures ContextFlags accurately represent the actual context data stored in REGDISPLAY

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

FileDescription
src/coreclr/vm/threads.cppAdds UNREACHABLE() after RtlRestoreContext call
src/coreclr/vm/arm64/stubs.cppClears CONTEXT_XSTATE flags in ARM64 ResumableFrame implementation
src/coreclr/vm/amd64/cgenamd64.cppClears CONTEXT_XSTATE flags in AMD64 ResumableFrame implementation

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janvorli commented Oct 8, 2025

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/azp run runtime-coreclr libraries-jitstress

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jkotas commented Oct 8, 2025

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Backport candidate?

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janvorli commented Oct 8, 2025

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Backport candidate?

Yes

@janvorli

janvorli commented Oct 9, 2025

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There is a couple of failing System.Net.XXX tests. All of the failures in these tests are asserting on

Assertion failed.
Interop.Sys.LSeek(this, 0, Interop.Sys.SeekWhence.SEEK_CUR) >= 0
at Microsoft.Win32.SafeHandles.SafeFileHandle.Open(String fullPath, FileMode mode, FileAccess access, FileShare share, FileOptions options, Int64 preallocationSize, UnixFileMode openPermissions, Int64& fileLength, UnixFileMode& filePermissions, Boolean failForSymlink, Boolean& wasSymlink, Func`4 createOpenException) in /_/src/libraries/System.Private.CoreLib/src/Microsoft/Win32/SafeHandles/SafeFileHandle.Unix.cs:line 208
at System.IO.Strategies.OSFileStreamStrategy..ctor(String path, FileMode mode, FileAccess access, FileShare share, FileOptions options, Int64 preallocationSize, Nullable`1 unixCreateMode) in /_/src/libraries/System.Private.CoreLib/src/System/IO/Strategies/OSFileStreamStrategy.cs:line 46
etc...

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janvorli commented Oct 9, 2025

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/ba-g test failures are #120577

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janvorli merged commit c392f56 into dotnet:mainOct 9, 2025
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janvorli commented Oct 9, 2025

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/backport to release/10.0

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Started backporting to release/10.0: https://github.com/dotnet/runtime/actions/runs/18388537629

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!PreemptiveGCDisabled assert failure from FiberDetachCallback during System.Runtime.Tests on win-arm64

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