linux-kernel - Re: [PATCH 3/8] s390/entry: shorten OUTSIDE macro

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Date:   Thu, 12 May 2022 19:21:49 +0200
From:   Heiko Carstens <hca@...ux.ibm.com>
To:     Heiko Carstens <hca@...ux.ibm.com>
Cc:     Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Jonas Paulsson <paulsson@...ux.vnet.ibm.com>,
        Ulrich Weigand <ulrich.weigand@...ibm.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Alexander Egorenkov <egorenar@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Andreas Krebbel <krebbel@...ux.ibm.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org
Subject: Re: [PATCH 3/8] s390/entry: shorten OUTSIDE macro

On Wed, May 11, 2022 at 02:05:27PM +0200, Heiko Carstens wrote:
> Since the minimum architecture level has been raised to z10 a shorter
> instruction sequence can be used to implement the OUTSIDE macro. This
> also reduces the number of used registers within that macro to one.
> 
> Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>
> ---
>  arch/s390/kernel/entry.S | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
> index a6b45eaa3450..e1664b45090f 100644
> --- a/arch/s390/kernel/entry.S
> +++ b/arch/s390/kernel/entry.S
> @@ -169,11 +169,9 @@ _LPP_OFFSET	= __LC_LPP
>  	 * @outside_label: jump here if @reg is outside of [@start..@end)
>  	 */
>  	.macro OUTSIDE reg,start,end,outside_label
> -	lgr	%r14,\reg
> -	larl	%r13,\start
> -	slgr	%r14,%r13
> -	lghi	%r13,\end - \start
> -	clgr	%r14,%r13
> +	larl	%r14,\start
> +	slgrk	%r14,\reg,%r14
> +	clgfi	%r14,\end - \start

Clever me.. slgrk was added with z196, and not z10.
So dropping this patch.