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Fri, 20 Mar 2026 11:39:10 +0000 (GMT) Date: Fri, 20 Mar 2026 12:39:09 +0100 From: Heiko Carstens To: Peter Zijlstra Cc: Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger , Juergen Christ , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH v2 0/9] s390: Improve this_cpu operations Message-ID: <20260320113909.9681Aad-hca@linux.ibm.com> References: <20260319120503.4046659-1-hca@linux.ibm.com> <20260319135612.GI3738786@noisy.programming.kicks-ass.net> Precedence: bulk X-Mailing-List: linux-s390@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: <20260319135612.GI3738786@noisy.programming.kicks-ass.net> X-TM-AS-GCONF: 00 X-Proofpoint-GUID: JzGcqd2yhUhikjNr24eiIVlsvFVn8juj X-Proofpoint-ORIG-GUID: JzGcqd2yhUhikjNr24eiIVlsvFVn8juj X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzIwMDA4NyBTYWx0ZWRfX3uW9SqUiD/g6 FCEph7SCDxHLVvf8W9/Lyxh/T9OhEICH6A7D0Sg1aG+t/DCGOPbjqJ1/l7YAbuwSCngkdkqmsLi BLL/tG7KBBsbKYSIK+VWSO0jH4xMgyZfAyjYwZjHFNVRSs4EhDx07rmfydTAnWK5aibnCv/YXRM v5RugvSs7wu55iwqFpIPQIgpy3UaUzIFm9DZxBHFnatGPVokvQihl3ZbMRPbIjTKGvCbKIqb982 cEKv81koaD1J5fVbpZwRYDIlOq7Y61pYLSHKXFR3fCChsjOzrtd6Z40U+3g8oiL5WQMgIRHInXu S+8NQeGXxuthmAyPEgI8OoGxVNDWGkvFA2OQllOe8ch/rCtWsygoiZztvBBKZrmgwjmyEgIV0zY 8Ei2cB2M4agye3lNFclWn9z7lxCWOSbrt93oL3OrheuQmmxFcX0jWXZ9rZ9VxoxSWcfX38PZsCJ b+cUryXvPvshXpSKDqg== X-Authority-Analysis: v=2.4 cv=Hf8ZjyE8 c=1 sm=1 tr=0 ts=69bd31e4 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=kj9zAlcOel0A:10 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=vyBrN-6Lojn0vnrHsAYA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-20_02,2026-03-19_05,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 lowpriorityscore=0 impostorscore=0 bulkscore=0 suspectscore=0 priorityscore=1501 spamscore=0 adultscore=0 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603200087 On Thu, Mar 19, 2026 at 02:56:12PM +0100, Peter Zijlstra wrote: > On Thu, Mar 19, 2026 at 01:04:54PM +0100, Heiko Carstens wrote: > > v2: > > > > - Add proper PERCPU_PTR cast to most patches to avoid tons of sparse > > warnings > > > > - Add missing __packed attribute to insn structure [Sashiko [2]] > > > > - Fix inverted if condition [Sashiko [2]] > > > > - Add missing user_mode() check [Sashiko [2]] > > > > - Move percpu_entry() call in front of irqentry_enter() call in all > > entry paths to avoid that potential this_cpu() operations overwrite > > the not-yet saved percpu code section indicator [Sashiko [2]] > > Would it make sense to add arch hooks to irqentry_{enter,exit}() ? I guess it would make sense to have some architecture hook which allows to run code on all entry/exit paths instead of duplicating the code n times. But apparently my code seems to have more bugs (e.g. I didn't consider kprobes which would make the instruction comparison not work). So this has to wait until I'm back after vacation.