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 10097E95A8E for ; Mon, 9 Oct 2023 11:52:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346325AbjJILwC (ORCPT ); Mon, 9 Oct 2023 07:52:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45166 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346281AbjJILwB (ORCPT ); Mon, 9 Oct 2023 07:52:01 -0400 Received: from mail-wm1-x331.google.com (mail-wm1-x331.google.com [IPv6:2a00:1450:4864:20::331]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BADF894 for ; Mon, 9 Oct 2023 04:51:59 -0700 (PDT) Received: by mail-wm1-x331.google.com with SMTP id 5b1f17b1804b1-40651a72807so43107515e9.1 for ; Mon, 09 Oct 2023 04:51:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1696852318; x=1697457118; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=QXAKj/7AkzuxGnbV+WvDfr1ujwsq/S+2CpiuERLuNt8=; b=QynhCd4PT10MWGPxJGkPaRiGlbSWlh9MS4GbsazuEtYr8joKRRfVhyjsePRhWiIond +q4Z6wezdgZRsRfj37BojshSVAY1k5im62kRarBxN1h0SLjYZz07cpGtW1CHdX+jeLv0 ejYZ6zeZjjm90NgYfIUqgKRZYdzmreEjfckkT1EwbReNbqLw8DxVMnb4GPBWczM+f5tQ 38guPIxlrtSrMaNX7GBqR3yl6djwYMeWjc11wzYZG8VwBXFzXxOVQlR9MN/lSOANf+uE HUIGN6+h5xVFo3RSkH9XSyLhKwr8w7ctFsKo6Ymz318XosJBTzq/1zkfJHSD+wtctyyc 8ofQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1696852318; x=1697457118; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=QXAKj/7AkzuxGnbV+WvDfr1ujwsq/S+2CpiuERLuNt8=; b=kdYCYC3s9a2Rfy8DZ+GtzbaTn8N+4RydkxOTlU3bR7kZ/Hr5b9a2vzzCS7nIpZyev3 OlWq9RsGC/to+cRsSa2yauIRjdVFVtsfnAcxuDnF+8fwS96YTpi7dNNZZ3Akqt3bBA3F 4VNr/GZiiWPCq5WfagD6OM4fIKSO8WicUpf/KsPNcYRBwOOUyiL6pW9JWF+ugRN2tTaj A41tkyyFY0ngFxPvqtyyYr9dN99pdFPMnrVgYcd1xtIfh2tBgUezmQMlCORjoVYRq44E niaNhOTK3XjfEu7KE+WnDCBx7fDbiZsqLGNddau0x7Y+FcDUtYRg5QJQVY16a+GaSdQg pw5Q== X-Gm-Message-State: AOJu0YyCdLo/erXOrT/pw8YCSahCWT99SlrjOlcDx7ON1e6bqUWGPSaX +/xX6hrmFBRXMlpq3XhTDpviMj8VWtQ= X-Google-Smtp-Source: AGHT+IGOZK+YFEV9b54mBSE/b9qRn4NNDY/nyS9aWduygpYQIxFHEqNyvZarUG0WIBziOPSPU8g11g== X-Received: by 2002:a05:600c:2b0e:b0:406:848f:8711 with SMTP id y14-20020a05600c2b0e00b00406848f8711mr13425463wme.21.1696852317947; Mon, 09 Oct 2023 04:51:57 -0700 (PDT) Received: from gmail.com (1F2EF237.nat.pool.telekom.hu. [31.46.242.55]) by smtp.gmail.com with ESMTPSA id o13-20020a05600c378d00b004063cd8105csm13149363wmr.22.2023.10.09.04.51.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Oct 2023 04:51:57 -0700 (PDT) Sender: Ingo Molnar Date: Mon, 9 Oct 2023 13:51:55 +0200 From: Ingo Molnar To: Uros Bizjak Cc: Linus Torvalds , x86@kernel.org, linux-kernel@vger.kernel.org, Andy Lutomirski , Nadav Amit , Brian Gerst , Denys Vlasenko , "H . Peter Anvin" , Peter Zijlstra , Thomas Gleixner , Borislav Petkov , Josh Poimboeuf Subject: Re: [PATCH 4/4] x86/percpu: Use C for percpu read/write accessors Message-ID: References: <20231004145137.86537-1-ubizjak@gmail.com> <20231004145137.86537-5-ubizjak@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Ingo Molnar wrote: > > * Uros Bizjak wrote: > > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > > index ecb256954351..1edf4a5b93ca 100644 > > --- a/arch/x86/Kconfig > > +++ b/arch/x86/Kconfig > > @@ -2393,7 +2393,7 @@ config CC_HAS_NAMED_AS > > > > config USE_X86_SEG_SUPPORT > > def_bool y > > - depends on CC_HAS_NAMED_AS && SMP > > + depends on CC_HAS_NAMED_AS && SMP && !KASAN > > + depends on CC_HAS_NAMED_AS && SMP && !KASAN > > So I'd rather express this as a Kconfig quirk line, and explain each quirk. > > Something like: > > depends on CC_HAS_NAMED_AS > depends on SMP > # > # -fsanitize=kernel-address (KASAN) is at the moment incompatible > # with named address spaces - see GCC bug #12345. > # > depends on !KASAN > > ... or so. BTW., while this OK for testing, this is too heavy handed for release purposes, so please only disable the KASAN instrumentation for the affected percpu accessors. See the various __no_sanitize* attributes available. I'd even suggest introducing a new attribute variant, specific to x86, prefixed with __no_sanitize_x86_seg or so, which would allow the eventual KASAN-instrumentation of the percpu accessors once the underlying GCC bug is fixed. Thanks, Ingo