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From: Arnd Bergmann <arnd@kernel.org>
Date: Wed, 9 Jun 2021 09:03:12 +0200
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To: musl@lists.openwall.com
Cc: Rich Felker <dalias@libc.org>, Markus Wichmann <nullplan@gmx.net>, 
	Florian Weimer <fweimer@redhat.com>
Content-Type: text/plain; charset="UTF-8"
Subject: Re: [musl] Backwards kernel compatibility

On Wed, Jun 2, 2021 at 1:52 PM Arnd Bergmann <arnd@kernel.org> wrote:
> On Wed, Jun 2, 2021 at 9:38 AM Martin Vajnar <martin.vajnar@gmail.com> wrote:

> >
> > The main source of overhead comes from the kernel 4.4 which on arm64
> > produces stack traces when not implemented syscall is invoked:
> >
> >     https://github.com/torvalds/linux/blob/afd2ff9b7e1b367172f18ba7f693dfb62bdcb2dc/arch/arm64/kernel/traps.c#L369
>
> That is clearly a bug that was fixed in mainline and backported to linux-4.14
> but not 4.4 or 4.9. I've sent a manual backport for inclusion in those kernels
> now.

The backport is now merged into the stable kernel trees and should be part of
4.4.272/4.9.272.

        Arnd