[PATCHv2] arm64/entry: Fix arm64-specific rseq brokenness

[Will Deacon]

On Tue, Jun 09, 2026 at 02:04:23PM +0200, Mathias Stearn wrote:
> Did the arm64-specific fix to rseq not get backportted to 7.0? We just
> ran our test suite against 7.0.10 which has the other rseq fixes and
> everything was fine on x86_64, but arm64 was frequently segfaulting.
> 
> I had an AI agent look into this and it reported:
> """
> The fix (commits b9eac6a9d93c, 82f572449cfe, 99428157dcf3,
> 411c1cf43039) first appeared in v7.1-rc1 and will be included in
> v7.1.0.
> 
> The three commits backported to linux-7.0.y:
> - 663121edad54 — "rseq: Revert to historical performance killing behaviour"
> - d242126fd21a — "rseq: Implement read only ABI enforcement for
> optimized RSEQ V2 mode"
> - fb742945d61a — "rseq: Reenable performance optimizations conditionally"
> 
> The arm64-specific fix (411c1cf43039 "arm64/entry: Fix arm64-specific
> rseq brokenness") was not backported to any stable branch — it will
> only appear in v7.1.0.
> """
> 
> Is it possible to get 411c1cf43039 backported to 7.0 or was it omitted
> intentionally?

You can send a backport to the stable maintainers:

https://docs.kernel.org/process/stable-kernel-rules.html#procedure-for-submitting-patches-to-the-stable-tree

(see option 3)

Will