From mboxrd@z Thu Jan 1 00:00:00 1970 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 2B375C433EF for ; Tue, 15 Feb 2022 09:40:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235974AbiBOJkU (ORCPT ); Tue, 15 Feb 2022 04:40:20 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:60484 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234609AbiBOJkR (ORCPT ); Tue, 15 Feb 2022 04:40:17 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 48CECE3881; Tue, 15 Feb 2022 01:40:07 -0800 (PST) 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 ams.source.kernel.org (Postfix) with ESMTPS id D11C2B8185C; Tue, 15 Feb 2022 09:40:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5D751C340F9; Tue, 15 Feb 2022 09:40:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644918004; bh=hv8AUuEMkapI1zY2x6Wj+fHd7ew8TaKYgsOBPTPrxmw=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=Qgz5FlPpKWsWGCSKlOreQeA49RzB47Yb61DpdQGkSqCvpQXhd/1xrVzA6HxgVkOAv HM/bWEouCkOrFRfLVSWs2TAF8Lvnm82Q7ljXZwaQBoSUgr63Phu8Xh5sdVnTyJI/ON lHIubRtLqY287IV/RrnG/iEcxILMQsa62F1uuyYy08GpnMfCYeG+01yyQZZn7UnJv7 021LqbfWi1zld4k8/8Wmx6fnGfR5no+iR4l8Y+N7e700ePaO67g4IaN0y0Orgs7STR gYOAdpNAvnxBHFJPJ1WrXSLgaxHaPAb+pRZVWsShzWY/LNUX3cgIy9+U52JoF4j03G HEN4j4yjmnzVQ== Received: by mail-wm1-f49.google.com with SMTP id j9-20020a05600c190900b0037bff8a24ebso1024782wmq.4; Tue, 15 Feb 2022 01:40:04 -0800 (PST) X-Gm-Message-State: AOAM531J5BbA2tq+ZrO2lMXu1GyShx/RoveGKKoSQ3d4y/40vJp0pF5k 5RSVmhlT3A9RLcg1FrOEAGhO7GBLSr55OHQcjeQ= X-Google-Smtp-Source: ABdhPJxpFSyo2tIfVZXx6xnWqAN7kXzL0SfiKGeaqLH7fIF3GRmujo8Iug1QC1Z1ypgNgRnGoRSGx0exr14yXtWS6QY= X-Received: by 2002:a05:600c:1d27:b0:37c:74bb:2b4d with SMTP id l39-20020a05600c1d2700b0037c74bb2b4dmr2314325wms.82.1644918002508; Tue, 15 Feb 2022 01:40:02 -0800 (PST) MIME-Version: 1.0 References: <20220214163452.1568807-1-arnd@kernel.org> <20220214163452.1568807-9-arnd@kernel.org> In-Reply-To: From: Arnd Bergmann Date: Tue, 15 Feb 2022 10:39:46 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 08/14] arm64: simplify access_ok() To: Ard Biesheuvel Cc: Linus Torvalds , Christoph Hellwig , linux-arch , Linux Memory Management List , Linux API , Arnd Bergmann , Linux Kernel Mailing List , Russell King , Will Deacon , Guo Ren , Brian Cain , Geert Uytterhoeven , Michal Simek , Thomas Bogendoerfer , Nick Hu , Greentime Hu , Dinh Nguyen , Stafford Horne , Helge Deller , Michael Ellerman , Peter Zijlstra , Ingo Molnar , Mark Rutland , Heiko Carstens , Rich Felker , "David S. Miller" , Richard Weinberger , X86 ML , Max Filippov , "Eric W. Biederman" , Andrew Morton , alpha , "open list:SYNOPSYS ARC ARCHITECTURE" , Linux ARM , linux-csky@vger.kernel.org, "open list:QUALCOMM HEXAGON..." , linux-ia64@vger.kernel.org, linux-m68k , "open list:MIPS" , Openrisc , "open list:PARISC ARCHITECTURE" , "open list:LINUX FOR POWERPC (32-BIT AND 64-BIT)" , linux-riscv , "open list:S390" , Linux-sh list , "open list:SPARC + UltraSPARC (sparc/sparc64)" , linux-um , "open list:TENSILICA XTENSA PORT (xtensa)" , Robin Murphy Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 15, 2022 at 10:21 AM Ard Biesheuvel wrote: > On Tue, 15 Feb 2022 at 10:13, Arnd Bergmann wrote: > > arm64 also has this leading up to the range check, and I think we'd no > longer need it: > > if (IS_ENABLED(CONFIG_ARM64_TAGGED_ADDR_ABI) && > (current->flags & PF_KTHREAD || test_thread_flag(TIF_TAGGED_ADDR))) > addr = untagged_addr(addr); I suspect the expensive part here is checking the two flags, as untagged_addr() seems to always just add a sbfx instruction. Would this work? #ifdef CONFIG_ARM64_TAGGED_ADDR_ABI #define access_ok(ptr, size) __access_ok(untagged_addr(ptr), (size)) #else // the else path is the default, this can be left out. #define access_ok(ptr, size) __access_ok((ptr), (size)) #endif Arnd