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 X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 57803C43610 for ; Thu, 22 Nov 2018 03:15:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1326520685 for ; Thu, 22 Nov 2018 03:15:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nifty.com header.i=@nifty.com header.b="hjyuNNvk" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1326520685 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=socionext.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391982AbeKVNw7 (ORCPT ); Thu, 22 Nov 2018 08:52:59 -0500 Received: from conuserg-09.nifty.com ([210.131.2.76]:51145 "EHLO conuserg-09.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732521AbeKVNw6 (ORCPT ); Thu, 22 Nov 2018 08:52:58 -0500 Received: from pug.e01.socionext.com (p14092-ipngnfx01kyoto.kyoto.ocn.ne.jp [153.142.97.92]) (authenticated) by conuserg-09.nifty.com with ESMTP id wAM3EZ3F004964; Thu, 22 Nov 2018 12:14:36 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conuserg-09.nifty.com wAM3EZ3F004964 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1542856476; bh=EC6OrDl+Pe6xGCqyh6yaEOjJ/Vdp3qzeTiZNHyrNG5o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hjyuNNvk1c0hopbgMPdWHghO38rHW7Rz523ZlAlLjuR/jZmbg6xv4y+/rflnb9sBg 6EDX192L0HhoEauJNDUcu0HY4X1StRdrXVGIRdAxerPOq5wIG17vsHbOuigF5eSbAi o58qT/ZTRPQpS6dNngbRbYl+ZWg1kjqbVZsWroUPWRL5RXRinTVQaGp8JYesvWJL9v s+8LZpxlVughcuzhgj5Idqpxj8zbbHJ649AZb/+LbG9/cOVISpDnlafXPVmeccpXUA pqDBojJ/khiBqbo0COGx6FPXoa1/bJ9mPvIfZ9J936PmSR7mUQui0u+4BupNKBceoy s6cDpCfY/vHbg== X-Nifty-SrcIP: [153.142.97.92] From: Masahiro Yamada To: Andrew Morton Cc: Luc Van Oostenryck , Nick Desaulniers , Kees Cook , Josh Triplett , Masahiro Yamada , linux-kernel@vger.kernel.org Subject: [PATCH v4 2/3] build_bug.h: remove negative-array fallback for BUILD_BUG_ON() Date: Thu, 22 Nov 2018 12:14:21 +0900 Message-Id: <1542856462-18836-2-git-send-email-yamada.masahiro@socionext.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1542856462-18836-1-git-send-email-yamada.masahiro@socionext.com> References: <1542856462-18836-1-git-send-email-yamada.masahiro@socionext.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The kernel can only be compiled with an optimization option (-O2, -Os, or the currently proposed -Og). Hence, __OPTIMIZE__ is always defined in the kernel source. The fallback for the -O0 case is just hypothetical and pointless. Moreover, commit 0bb95f80a38f ("Makefile: Globally enable VLA warning") enabled -Wvla warning. The use of variable length arrays is banned. Signed-off-by: Masahiro Yamada Acked-by: Kees Cook Reviewed-by: Nick Desaulniers Tested-by: Nick Desaulniers --- Changes in v4: None Changes in v3: None Changes in v2: None include/linux/build_bug.h | 14 -------------- 1 file changed, 14 deletions(-) diff --git a/include/linux/build_bug.h b/include/linux/build_bug.h index 43d1fd5..d415c64 100644 --- a/include/linux/build_bug.h +++ b/include/linux/build_bug.h @@ -51,23 +51,9 @@ * If you have some code which relies on certain constants being equal, or * some other compile-time-evaluated condition, you should use BUILD_BUG_ON to * detect if someone changes it. - * - * The implementation uses gcc's reluctance to create a negative array, but gcc - * (as of 4.4) only emits that error for obvious cases (e.g. not arguments to - * inline functions). Luckily, in 4.3 they added the "error" function - * attribute just for this type of case. Thus, we use a negative sized array - * (should always create an error on gcc versions older than 4.4) and then call - * an undefined function with the error attribute (should always create an - * error on gcc 4.3 and later). If for some reason, neither creates a - * compile-time error, we'll still have a link-time error, which is harder to - * track down. */ -#ifndef __OPTIMIZE__ -#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)])) -#else #define BUILD_BUG_ON(condition) \ BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) -#endif /** * BUILD_BUG - break compile if used. -- 2.7.4