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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 DB75CC4338F for ; Thu, 29 Jul 2021 16:18:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BCF9260EBB for ; Thu, 29 Jul 2021 16:18:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231475AbhG2QSw (ORCPT ); Thu, 29 Jul 2021 12:18:52 -0400 Received: from foss.arm.com ([217.140.110.172]:52068 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229739AbhG2QSv (ORCPT ); Thu, 29 Jul 2021 12:18:51 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 9167DD6E; Thu, 29 Jul 2021 09:18:48 -0700 (PDT) Received: from arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id ABA043F881; Thu, 29 Jul 2021 09:18:47 -0700 (PDT) Date: Thu, 29 Jul 2021 17:17:26 +0100 From: Dave Martin To: Mark Brown Cc: Catalin Marinas , Will Deacon , Shuah Khan , linux-arm-kernel@lists.infradead.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v2 1/4] kselftest/arm64: Provide a helper binary and "library" for SVE RDVL Message-ID: <20210729161726.GQ1724@arm.com> References: <20210728163318.51492-1-broonie@kernel.org> <20210728163318.51492-2-broonie@kernel.org> <20210729095222.GH1724@arm.com> <20210729112217.GK4670@sirena.org.uk> <20210729132701.GH20179@e103592.cambridge.arm.com> <20210729160334.GQ4670@sirena.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210729160334.GQ4670@sirena.org.uk> User-Agent: Mutt/1.5.23 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Thu, Jul 29, 2021 at 05:03:34PM +0100, Mark Brown wrote: > On Thu, Jul 29, 2021 at 02:27:04PM +0100, Dave P Martin wrote: > > On Thu, Jul 29, 2021 at 12:22:17PM +0100, Mark Brown wrote: > > > > Yeah, it doesn't seem to be in the slightest bit idiomatic for the arm64 > > > asm code the kernel has. I don't know if you think it's worth adding > > > that to SYM_FUNC_START now we have it though? > > > Actually, I think the core definition of SYM_FUNC_END() in > > does this. > > Ah, so it does. > > > It would be good to pick up the common linkage macros; if we have to > > sprinkle .type manually all over the tests people will likely make > > mistakes, to that's probably not worth it. > > > If picking up the macros isn't trivial to do, I guess it's not that > > important at this stage. > > They're not exported from the kernel at all at the minute so that'd be a > whole new block of work that feels out of scope here, we already have a > stack of asm code in selftests. Agreed. Feels like it might be a good idea at some point, but it's orthogonal to this series, and for now nothing breaks. > > > that those are outside the kernel either. We will have to do something > > > like that if anyone starts building userspace with BTI though (or I > > > might just shove a BTI C in there unconditionally, I'm sure we'll cope > > > with the overhead on older systems). > > > I thought about that, but that .S file isn't annotated as supporting > > BTI, so I guess there's no problem for now(?) > > True, we'll generate linker warnings but it should otherwise sort itself > out unless someone forced BTI mode. The whole annotation thing really > isn't fun to deal with for assembly code, hopefully there'll be some > toolchain improvements in this area at some point. Ack Cheers ---Dave