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[2620:137:e000::1:20]) by mx.google.com with ESMTP id z7-20020aa7d407000000b0046a00ff51f4si706943edq.594.2022.11.22.08.32.46; Tue, 22 Nov 2022 08:33:19 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linutronix.de header.s=2020 header.b=Wn7oefSB; dkim=neutral (no key) header.i=@linutronix.de; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=linutronix.de Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232997AbiKVQ0t (ORCPT + 99 others); Tue, 22 Nov 2022 11:26:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60250 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232788AbiKVQ0q (ORCPT ); Tue, 22 Nov 2022 11:26:46 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E54B4205DB; Tue, 22 Nov 2022 08:26:44 -0800 (PST) Date: Tue, 22 Nov 2022 16:26:41 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1669134403; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=v7z18Qsa6WKgfd8idYg0zbdnSVfun8wkjQ1dd6pBtws=; b=Wn7oefSBIV1qyIlXDqpUW4zqQP5CPirWg7oJCx41mipW5DsnmAKXzm4jFLrzmBha3IqA0v S40naqMJ0RE/H7PKJi9lXw1ed+Xp8cZpKQMRnLRnHfvCLpFa2661gJrteOkWhYIuNPvik2 VultdZfE+PRBGYNVfwW2zRdjXvXznQcQaqhWED1e82Y7kGwi37AJDn6ERPAKptrXNg83Yt HBZohkBYXX+mWhkc/iu6LSpYqh1pAZmNh4XXvsaWEinzQ9UWaA2+EqXfkZ/YtLlVlPYqF4 EdTh98v1BRzFS+hxrqm89YFYlGDrEn6O8s96Syqgwd5qJJRiWgdBYckbF8cKgA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1669134403; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=v7z18Qsa6WKgfd8idYg0zbdnSVfun8wkjQ1dd6pBtws=; b=cAIEZQJPM4qu43O+saG7R6wjLZD8lCYKsvBdO4uye7axhnqFEpS2z4PKCxKiCSEPj4vAtP c7ZRqa+8YYQ25UDg== From: "tip-bot2 for YingChi Long" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/fpu] x86/fpu: Use _Alignof to avoid undefined behavior in TYPE_ALIGN Cc: YingChi Long , Borislav Petkov , Nick Desaulniers , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20220925153151.2467884-1-me@inclyc.cn> References: <20220925153151.2467884-1-me@inclyc.cn> MIME-Version: 1.0 Message-ID: <166913440179.4906.11745141572917292511.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED,SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1750214690871999571?= X-GMAIL-MSGID: =?utf-8?q?1750214690871999571?= The following commit has been merged into the x86/fpu branch of tip: Commit-ID: 55228db2697c09abddcb9487c3d9fa5854a932cd Gitweb: https://git.kernel.org/tip/55228db2697c09abddcb9487c3d9fa5854a932cd Author: YingChi Long AuthorDate: Fri, 18 Nov 2022 08:55:35 +08:00 Committer: Borislav Petkov CommitterDate: Tue, 22 Nov 2022 17:13:03 +01:00 x86/fpu: Use _Alignof to avoid undefined behavior in TYPE_ALIGN WG14 N2350 specifies that it is an undefined behavior to have type definitions within offsetof", see https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2350.htm This specification is also part of C23. Therefore, replace the TYPE_ALIGN macro with the _Alignof builtin to avoid undefined behavior. (_Alignof itself is C11 and the kernel is built with -gnu11). ISO C11 _Alignof is subtly different from the GNU C extension __alignof__. Latter is the preferred alignment and _Alignof the minimal alignment. For long long on x86 these are 8 and 4 respectively. The macro TYPE_ALIGN's behavior matches _Alignof rather than __alignof__. [ bp: Massage commit message. ] Signed-off-by: YingChi Long Signed-off-by: Borislav Petkov Reviewed-by: Nick Desaulniers Link: https://lore.kernel.org/r/20220925153151.2467884-1-me@inclyc.cn --- arch/x86/kernel/fpu/init.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c index 8946f89..851eb13 100644 --- a/arch/x86/kernel/fpu/init.c +++ b/arch/x86/kernel/fpu/init.c @@ -133,9 +133,6 @@ static void __init fpu__init_system_generic(void) fpu__init_system_mxcsr(); } -/* Get alignment of the TYPE. */ -#define TYPE_ALIGN(TYPE) offsetof(struct { char x; TYPE test; }, test) - /* * Enforce that 'MEMBER' is the last field of 'TYPE'. * @@ -143,8 +140,8 @@ static void __init fpu__init_system_generic(void) * because that's how C aligns structs. */ #define CHECK_MEMBER_AT_END_OF(TYPE, MEMBER) \ - BUILD_BUG_ON(sizeof(TYPE) != ALIGN(offsetofend(TYPE, MEMBER), \ - TYPE_ALIGN(TYPE))) + BUILD_BUG_ON(sizeof(TYPE) != \ + ALIGN(offsetofend(TYPE, MEMBER), _Alignof(TYPE))) /* * We append the 'struct fpu' to the task_struct: