From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) by sourceware.org (Postfix) with ESMTP id 61244386EC63 for ; Thu, 16 Apr 2020 23:03:03 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 61244386EC63 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: sourceware.org; spf=fail smtp.mailfrom=segher@kernel.crashing.org Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 03GN2bHF015254; Thu, 16 Apr 2020 18:02:37 -0500 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 03GN2ZC2015253; Thu, 16 Apr 2020 18:02:35 -0500 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Thu, 16 Apr 2020 18:02:35 -0500 From: Segher Boessenkool To: Florian Weimer Cc: Rich Felker , musl@lists.openwall.com, libc-alpha@sourceware.org, linuxppc-dev@lists.ozlabs.org, Nicholas Piggin , libc-dev@lists.llvm.org Subject: Re: [musl] Powerpc Linux 'scv' system call ABI proposal take 2 Message-ID: <20200416230235.GG26902@gate.crashing.org> References: <1586931450.ub4c8cq8dj.astroid@bobo.none> <20200415225539.GL11469@brightrain.aerifal.cx> <87k12gf32r.fsf@mid.deneb.enyo.de> <20200416153509.GT11469@brightrain.aerifal.cx> <87sgh3e613.fsf@mid.deneb.enyo.de> <20200416165257.GY11469@brightrain.aerifal.cx> <87ftd3e1vg.fsf@mid.deneb.enyo.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87ftd3e1vg.fsf@mid.deneb.enyo.de> User-Agent: Mutt/1.4.2.3i X-Spam-Status: No, score=-15.6 required=5.0 tests=BAYES_00, JMQ_SPF_NEUTRAL, KAM_DMARC_STATUS, KAM_NUMSUBJECT, RCVD_IN_DNSWL_NONE, TXREP, T_SPF_HELO_PERMERROR, T_SPF_PERMERROR autolearn=no autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 16 Apr 2020 23:03:04 -0000 On Thu, Apr 16, 2020 at 08:12:19PM +0200, Florian Weimer wrote: > > I think my choice would be just making the inline syscall be a single > > call insn to an asm source file that out-of-lines the loading of TOC > > pointer and call through it or branch based on hwcap so that it's not > > repeated all over the place. > > I don't know how problematic control flow out of an inline asm is on > POWER. But this is basically the -moutline-atomics approach. Control flow out of inline asm (other than with "asm goto") is not allowed at all, just like on any other target (and will not work in practice, either -- just like on any other target). But the suggestion was to use actual assembler code, not inline asm? Segher