From patchwork Thu Sep 29 18:07:31 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Paul E. McKenney" X-Patchwork-Id: 12994532 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BFA40C4321E for ; Thu, 29 Sep 2022 18:07:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234945AbiI2SHi (ORCPT ); Thu, 29 Sep 2022 14:07:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57386 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235336AbiI2SHf (ORCPT ); Thu, 29 Sep 2022 14:07:35 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B973A1BB6F6; Thu, 29 Sep 2022 11:07:34 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 4AFBF62129; Thu, 29 Sep 2022 18:07:34 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 60174C43148; Thu, 29 Sep 2022 18:07:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1664474853; bh=dxVVyAI/XsDb/XxEurj/fyG2d+UBorNbtmn4Ig6rVNY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FwBur71iPrFaH4Ymbzw7w7w8nzr94QBsKWYizdb6U0oA+JhgrsQbzGA20b6otNv4C bXdAuQz5OOnJJBoH1oXym6/1abW/DdkitXnJ8z3Xj8SofgdBt6+u0s+FFVvbDM1KTN gJeu5w/k5PXnRMXCPdUsoJIW+CjUcbZYJr4RWpQFi/Y0/2rTULN6VDxFmMLSnimklR 0mtt7BFBDu1MjpgBGj/yJRlVpFo+DCEmDzce8gyK/sE47vI/4mITwsyCvbPg/Ew1iA 2q5SUQVPsAJ6qli0d8lxM/n1L3FwwTkKmRR6rBn1MqPZsEFsV5Uk1i25zlIuVg1w+r WIT/Y6TqnH8GQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id B90755C0F66; Thu, 29 Sep 2022 11:07:32 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, rostedt@goodmis.org, "Paul E. McKenney" , Neeraj Upadhyay , Frederic Weisbecker , Boqun Feng , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Thomas Gleixner , John Ogness , Petr Mladek , linux-s390@vger.kernel.org Subject: [PATCH RFC v2 rcu 8/8] arch/s390: Add ARCH_HAS_NMI_SAFE_THIS_CPU_OPS Kconfig option Date: Thu, 29 Sep 2022 11:07:31 -0700 Message-Id: <20220929180731.2875722-8-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20220929180714.GA2874192@paulmck-ThinkPad-P17-Gen-1> References: <20220929180714.GA2874192@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org The s390 architecture uses either a cmpxchg loop (old systems) or the laa add-to-memory instruction (new systems) to implement this_cpu_add(), both of which are NMI safe. This means that the old and more-efficient srcu_read_lock() may be used in NMI context, without the need for srcu_read_lock_nmisafe(). Therefore, add the new Kconfig option ARCH_HAS_NMI_SAFE_THIS_CPU_OPS to arch/arm64/Kconfig, which will cause NEED_SRCU_NMI_SAFE to be deselected, thus preserving the current srcu_read_lock() behavior. Link: https://lore.kernel.org/all/20220910221947.171557773@linutronix.de/ Suggested-by: Neeraj Upadhyay Suggested-by: Frederic Weisbecker Suggested-by: Boqun Feng Signed-off-by: Paul E. McKenney Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Alexander Gordeev Cc: Christian Borntraeger Cc: Sven Schnelle Cc: Thomas Gleixner Cc: John Ogness Cc: Petr Mladek Cc: --- arch/s390/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 318fce77601d..0acdfda33290 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -73,6 +73,7 @@ config S390 select ARCH_HAS_GIGANTIC_PAGE select ARCH_HAS_KCOV select ARCH_HAS_MEM_ENCRYPT + select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS select ARCH_HAS_PTE_SPECIAL select ARCH_HAS_SCALED_CPUTIME select ARCH_HAS_SET_MEMORY