Date: Mon, 5 Jan 2026 09:51:08 +0100 (CET) From: Ronald Klop <ronald-lists@klop.ws> To: freebsd-arm@FreeBSD.org Subject: Re: [Bug 292195] arm64: panic on coredump with sve instructions Message-ID: <904455433.482.1767603068277@localhost> In-Reply-To: <bug-292195-7@https.bugs.freebsd.org/bugzilla/>
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[-- Attachment #1 --] Sounds like an investigation candidate for why pkg builder ampere1 crashes now and than? Ronald. Van: bugzilla-noreply@freebsd.org Datum: maandag, 5 januari 2026 09:39 Aan: freebsd-arm@FreeBSD.org Onderwerp: [Bug 292195] arm64: panic on coredump with sve instructions > > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=292195 > > Bug ID: 292195 > Summary: arm64: panic on coredump with sve instructions > Product: Base System > Version: 16.0-CURRENT > Hardware: Any > OS: Any > Status: New > Severity: Affects Some People > Priority: --- > Component: arm > Assignee: freebsd-arm@FreeBSD.org > Reporter: william.a@carrel.org > > Created attachment 266838 > --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=266838&action=edit > vfp.c.patch > > When trying to reproduce bug 292177 on 16-CURRENT I unexpectedly encountered a > kernel panic. It looks like the panic was unique to coredumping in SVE code. > > The coredump logic calls get_arm64_sve twice: once to get the note size, and > once to get the data. The note size calculation depended on the volatile > PCB_FP_SVEVALID flag. If this flag was cleared between the two calls (e.g., due > to a context switch clearing the flag to comply with the ABI), the second call > would expect a smaller buffer size than the first, triggering the KASSERT panic > ("invalid size"). > > Fix this by: > 1. Using pcb->pcb_svesaved != NULL (a stable indicator of SVE usage) to > determine the note size. > 2. Calling vfp_to_sve_sync() if SVE is not currently valid but SVE state is > saved, ensuring the SVE buffer in the core dump contains the most up-to-date > register values. > > -- > You are receiving this mail because: > You are the assignee for the bug. > > > [-- Attachment #2 --] <html><head></head><body>Sounds like an investigation candidate for why pkg builder ampere1 crashes now and than?<br> <br> Ronald.<br> <p><strong>Van:</strong> bugzilla-noreply@freebsd.org<br> <strong>Datum:</strong> maandag, 5 januari 2026 09:39<br> <strong>Aan:</strong> freebsd-arm@FreeBSD.org<br> <strong>Onderwerp:</strong> [Bug 292195] arm64: panic on coredump with sve instructions</p> <blockquote style="padding-right: 0px; padding-left: 5px; margin-left: 5px; border-left: #000000 2px solid; margin-right: 0px"> <div class="MessageRFC822Viewer" id="P"> <div class="TextPlainViewer" id="P.P"><a href="https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=292195">https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=292195</a><br>; <br> Bug ID: 292195<br> Summary: arm64: panic on coredump with sve instructions<br> Product: Base System<br> Version: 16.0-CURRENT<br> Hardware: Any<br> OS: Any<br> Status: New<br> Severity: Affects Some People<br> Priority: ---<br> Component: arm<br> Assignee: freebsd-arm@FreeBSD.org<br> Reporter: william.a@carrel.org<br> <br> Created attachment 266838<br> --> <a href="https://bugs.freebsd.org/bugzilla/attachment.cgi?id=266838&action=edit">https://bugs.freebsd.org/bugzilla/attachment.cgi?id=266838&action=edit</a><br>; vfp.c.patch<br> <br> When trying to reproduce bug 292177 on 16-CURRENT I unexpectedly encountered a<br> kernel panic. It looks like the panic was unique to coredumping in SVE code.<br> <br> The coredump logic calls get_arm64_sve twice: once to get the note size, and<br> once to get the data. The note size calculation depended on the volatile<br> PCB_FP_SVEVALID flag. If this flag was cleared between the two calls (e.g., due<br> to a context switch clearing the flag to comply with the ABI), the second call<br> would expect a smaller buffer size than the first, triggering the KASSERT panic<br> ("invalid size").<br> <br> Fix this by:<br> 1. Using pcb->pcb_svesaved != NULL (a stable indicator of SVE usage) to<br> determine the note size.<br> 2. Calling vfp_to_sve_sync() if SVE is not currently valid but SVE state is<br> saved, ensuring the SVE buffer in the core dump contains the most up-to-date<br> register values.<br> <br> -- <br> You are receiving this mail because:<br> You are the assignee for the bug.</div> <hr></div> </blockquote> <br> </body></html>home | help
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