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 94C1BEB64DA for ; Sun, 2 Jul 2023 18:51:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229644AbjGBSvS (ORCPT ); Sun, 2 Jul 2023 14:51:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59484 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229894AbjGBSvS (ORCPT ); Sun, 2 Jul 2023 14:51:18 -0400 Received: from 1wt.eu (ded1.1wt.eu [163.172.96.212]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id DAFABC6; Sun, 2 Jul 2023 11:51:12 -0700 (PDT) Received: (from willy@localhost) by pcw.home.local (8.15.2/8.15.2/Submit) id 362Ioxts017366; Sun, 2 Jul 2023 20:50:59 +0200 Date: Sun, 2 Jul 2023 20:50:59 +0200 From: Willy Tarreau To: Zhangjin Wu Cc: thomas@t-8ch.de, arnd@arndb.de, david.laight@aculab.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH v5 07/14] tools/nolibc: arch-loongarch.h: shrink with SYSCALL_CLOBBERLIST Message-ID: <20230702185059.GG16233@1wt.eu> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Wed, Jun 28, 2023 at 09:22:21PM +0800, Zhangjin Wu wrote: > my_syscall share a same long clobber list, define a macro for them. > > Signed-off-by: Zhangjin Wu > --- > tools/include/nolibc/arch-loongarch.h | 25 +++++++++++-------------- > 1 file changed, 11 insertions(+), 14 deletions(-) > > diff --git a/tools/include/nolibc/arch-loongarch.h b/tools/include/nolibc/arch-loongarch.h > index 292d6a58dc87..fbb4844f7993 100644 > --- a/tools/include/nolibc/arch-loongarch.h > +++ b/tools/include/nolibc/arch-loongarch.h > @@ -23,6 +23,10 @@ > */ > #define __ARCH_WANT_SYS_PSELECT6 > > +#define SYSCALL_CLOBBERLIST \ > + "memory", "$t0", "$t1", "$t2", "$t3", \ > + "$t4", "$t5", "$t6", "$t7", "$t8" > + That's a good idea, but please be careful when adding macro definitions, we're in code that is used by user space we have no control on, and we're polluting the end user's macro namespace with plenty of names. While one could argue that it's unlikely that some program already defines and uses SYSCALL_CLOBBERLIST, actually with low-level code it's fairly possible. Till now most of the definitions were for stuff that user-space really needs (e.g. STDIN_FILENO, various integer limits). If we start to declare random macros for internal use, at least we should probably prefix them with _NOLIBC_ or something like this to avoid the risk of collision. Willy