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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT 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 36E35C43381 for ; Fri, 8 Mar 2019 18:53:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 03A9F20857 for ; Fri, 8 Mar 2019 18:53:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728113AbfCHSx3 (ORCPT ); Fri, 8 Mar 2019 13:53:29 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59962 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726776AbfCHSx3 (ORCPT ); Fri, 8 Mar 2019 13:53:29 -0500 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2E69B3092664; Fri, 8 Mar 2019 18:53:29 +0000 (UTC) Received: from treble (ovpn-120-61.rdu2.redhat.com [10.10.120.61]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 74CD72635C; Fri, 8 Mar 2019 18:53:24 +0000 (UTC) Date: Fri, 8 Mar 2019 12:53:21 -0600 From: Josh Poimboeuf To: Peter Zijlstra Cc: torvalds@linux-foundation.org, tglx@linutronix.de, hpa@zytor.com, julien.thierry@arm.com, will.deacon@arm.com, luto@amacapital.net, mingo@kernel.org, catalin.marinas@arm.com, james.morse@arm.com, valentin.schneider@arm.com, brgerst@gmail.com, luto@kernel.org, bp@alien8.de, dvlasenk@redhat.com, linux-kernel@vger.kernel.org, dvyukov@google.com, rostedt@goodmis.org Subject: Re: [PATCH 03/20] x86/uaccess: Move copy_user_handle_tail into asm Message-ID: <20190308185321.jukfavqk6pl3ifev@treble> References: <20190307114511.870090179@infradead.org> <20190307115159.349746915@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190307115159.349746915@infradead.org> User-Agent: NeoMutt/20180716 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Fri, 08 Mar 2019 18:53:29 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 07, 2019 at 12:45:14PM +0100, Peter Zijlstra wrote: > /* > + * Try to copy last bytes and clear the rest if needed. > + * Since protection fault in copy_from/to_user is not a normal situation, > + * it is not necessary to optimize tail handling. > + * > + * Input: > + * rdi destination > + * rsi source > + * rdx count > + * > + * Output: > + * eax uncopied bytes or 0 if successful. > + */ > +ALIGN; > +copy_user_handle_tail: > + movl %edx,%ecx > +1: rep movsb > +2: mov %ecx,%eax > + ASM_CLAC > + ret > + > + _ASM_EXTABLE_UA(1b, 2b) > +ENDPROC(copy_user_handle_tail) This is an unstructured piece of code rather than a callable function, END would probably be more appropriate. Or maybe it should just be a local label (.Lcopy_user_handle_tail) because I don't think the alignment and ELF symbol size are even needed. -- Josh