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Mon, 21 Sep 2026 10:17:58 +0000 (GMT) Received: from osiris (unknown [9.111.14.239]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTPS; Mon, 21 Sep 2026 10:17:58 +0000 (GMT) Date: Mon, 21 Sep 2026 12:17:57 +0200 From: Heiko Carstens To: Mark Rutland Cc: David Laight , Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger , Mete Durlu , Peter Zijlstra , Juergen Christ , Ilya Leoshkevich , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH v3 11/11] s390/percpu: Rework to simplify percpu_entry() and percpu_exit() Message-ID: <20260921101757.9433Bc4-hca@linux.ibm.com> References: <20260921084005.4022574-1-hca@linux.ibm.com> <20260921084005.4022574-12-hca@linux.ibm.com> <20260921105518.26f3dcf7@pumpkin> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-ORIG-GUID: eJ_f6wGakvMO0OVlxVTBoXJ5INmUFEJW X-Authority-Analysis: v=2.4 cv=I43w19gg c=1 sm=1 tr=0 ts=6ab1045c cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=kj9zAlcOel0A:10 a=VdqzKS8jKosA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=iQ6ETzBq9ecOQQE5vZCe:22 a=VnNF1IyMAAAA:8 a=CwPWOeoUAzdWqaCKj24A:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTIxMDE0NSBTYWx0ZWRfX9FQomctUJGOB TNHJax8dvx3ap6SNCRvE0+oO4iVmEjPfP94hHCnmjeCUFoTHoQ3hYQ1ND+NUtLL7XdpNRizcwV2 gkKrPiOLmt5tuiFU89riIkB8WK1RFuFYRIxH1ooupmFRvPoQwgyjYS9U6l4SSrcowZN9L4lfnui jze5QRfRmRMouE5W1p9zN/b0hC7W6HsHodQQNXN3Qp/F+/JH6dagctRNfr+vOYCkYO2trl/Lovf Qzidcjh79UgC9tsZ2jI/qqOXu+CE74anal8OgpxKSYJP+y6nWZoO31SgsK6Qv7TvK5fU/AIPuY+ REs/lV5YCcskGhC2Ls4CuL/c58/eZD82tEJbogS9Zz7QIQFo7LdHKYwesz+zCjPcISkl0fV6s2Q huHmqZRZT/a3k1KUcYjBbHKZsryccufSVlh4xeZodR0IivGgvU76gMSVOY4qsHsBEXpYci8vRsO BfL8M3aLijvs02gMS+A== X-Proofpoint-Spam-Info: AW1haW4tMjYwOTIxMDE0NSBTYWx0ZWRfX97OCfZ0lqF4y hwEHpzUkGJocFaPtkvqjsf1u4381tCbZlzSmPrEgbvhYx8g6RQIdp+MLOiSYpERCQFaL+8K2/lM Xlkc4PCam0UcONz1pwjzKvKT1p9BFbY= X-Proofpoint-GUID: P4F0f5y_Cdss2-HjWKz2fSlhTOvdUOpb X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-21_03,2026-09-16_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 clxscore=1015 adultscore=0 suspectscore=0 impostorscore=0 lowpriorityscore=0 bulkscore=0 phishscore=0 priorityscore=1501 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609210145 On Mon, Sep 21, 2026 at 11:07:04AM +0100, Mark Rutland wrote: > On Mon, Sep 21, 2026 at 10:55:18AM +0100, David Laight wrote: > > On Mon, 21 Sep 2026 10:40:05 +0200 > > Heiko Carstens wrote: > > > > + regpcp = FIELD_GET(PCPU_REG_PCP, regval); > > > + regoff = FIELD_GET(PCPU_REG_OFF, regval); > > ... > > > +#define PCPU_REG_PCP_SHIFT 0 > > > +#define PCPU_REG_PCP GENMASK(3, 0) > > > +#define PCPU_REG_OFF_SHIFT 4 > > > +#define PCPU_REG_OFF GENMASK(7, 4) > > ... > > > +#define __PCPU_CALC_REGVAL(regpcp, regoff) \ > > > + "(" regpcp " << " __stringify(PCPU_REG_PCP_SHIFT) ") |" \ > > > + "(" regoff " << " __stringify(PCPU_REG_OFF_SHIFT) ")" > > > > I'm not a big fan of GENMASK() + FIELD_GET() and I'm not at all sure it > > really helps here. > > It's the same pattern already used by the extable code. > > While _you_ don't like it, that's not a universal opinion (and FWIW, I > prefer the FIELD_GET() approach). > > I'll leave it to Heiko and co to choose whatever style they prefer, as > it's their architecture port... As Mark said: it is already used, and in addition I would like to have s390 architecture code quite similar to other architectures whenever possible. This simplifies cross architecture changes, even though it seems unlikely that somebody would ever touch this particular code across architectures.