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=-11.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 A36ABC433DB for ; Thu, 25 Feb 2021 20:07:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6402B64F25 for ; Thu, 25 Feb 2021 20:07:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232906AbhBYUHa (ORCPT ); Thu, 25 Feb 2021 15:07:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:58756 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229993AbhBYUHY (ORCPT ); Thu, 25 Feb 2021 15:07:24 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2B79460235; Thu, 25 Feb 2021 20:06:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1614283598; bh=CYRFdOJBvR/yxA/tEE02fkILr27KR8sdKgRLGbX0XJM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=S33rec2d419BnIoz2NtABr9//difXwnak25NChMOhjvN6ZTsyFaqfjV2ucFur3pq4 fHya/yOpRzuBJn5cSTbd0GcRU6zLDuJOYQftypmqde19m1QDK/d5lLtSgMHIFEa3hX 2RWT6bilc9L1vE/FyPF+lcKa9gjPUjzUPT7IQp3E= Date: Thu, 25 Feb 2021 12:06:37 -0800 From: Andrew Morton To: Kees Cook Cc: Arnd Bergmann , Masahiro Yamada , Nathan Chancellor , Nick Desaulniers , Arnd Bergmann , Miguel Ojeda , Marco Elver , Sami Tolvanen , Arvind Sankar , Randy Dunlap , clang-built-linux@googlegroups.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] linux/compiler-clang.h: define HAVE_BUILTIN_BSWAP* Message-Id: <20210225120637.8e2a234f192952829fc5f471@linux-foundation.org> In-Reply-To: <202102251203.03762F77@keescook> References: <20210225164513.3667778-1-arnd@kernel.org> <202102251203.03762F77@keescook> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 25 Feb 2021 12:03:48 -0800 Kees Cook wrote: > On Thu, Feb 25, 2021 at 05:45:09PM +0100, Arnd Bergmann wrote: > > From: Arnd Bergmann > > > > Separating compiler-clang.h from compiler-gcc.h inadventently dropped the > > definitions of the three HAVE_BUILTIN_BSWAP macros, which requires falling > > back to the open-coded version and hoping that the compiler detects it. > > > > Since all versions of clang support the __builtin_bswap interfaces, > > add back the flags and have the headers pick these up automatically. > > > > This results in a 4% improvement of compilation speed for arm defconfig. > > > > Fixes: 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive") > > Signed-off-by: Arnd Bergmann > > Cc: stable@vger.kernel.org I figured 4% better compile time isn't significant enough to justify a backport. Thoughts? > Reviewed-by: Kees Cook