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=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT 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 48A9AC6778A for ; Thu, 5 Jul 2018 18:00:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EA22B23DB7 for ; Thu, 5 Jul 2018 18:00:21 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="OWGCM+lz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EA22B23DB7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753859AbeGESAS (ORCPT ); Thu, 5 Jul 2018 14:00:18 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:36256 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753405AbeGESAQ (ORCPT ); Thu, 5 Jul 2018 14:00:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=7fkjtg9sPWTn/G/yziX8+lDXoSKoQKKHXJHNQ4+h17o=; b=OWGCM+lzaQ5tSK15e7vgJYcPt V9hePGm7lxiujpSmzmlDeHlQy+rKGH4H3krMN8OST8AwW8r/Wbc7Jrlhlk+p23yxejgJgFzJQhITr SpBpkA+4N9TFqsy2GLIHfNgKBxFVe/MN5sdgr4WIikSNwADMOoIxvtJNnX7bSUjEHna68+PPRbTac ++5bz0tCaZcGK6bNAn9cfM9TV5SG+pquakLPlpQ9lSU7MrhXjSzZGL+3+4TOTC79QAJDGyRcL4FSj 0aztqIS52exPLIBD1lIQcsjxiWTorWu+nJV40nGRDz8oGANFbhRjf1BFtfBnu/5rQeXlJCiacjH71 maPZtLdhw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fb8Y6-0002wy-9T; Thu, 05 Jul 2018 18:00:10 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C764020289CF4; Thu, 5 Jul 2018 20:00:08 +0200 (CEST) Date: Thu, 5 Jul 2018 20:00:08 +0200 From: Peter Zijlstra To: Guo Ren Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, daniel.lezcano@linaro.org, jason@lakedaemon.net, arnd@arndb.de, c-sky_gcc_upstream@c-sky.com, gnu-csky@mentor.com, thomas.petazzoni@bootlin.com, wbx@uclibc-ng.org, green.hu@gmail.com Subject: Re: [PATCH V2 11/19] csky: Atomic operations Message-ID: <20180705180008.GG2530@hirez.programming.kicks-ass.net> References: <860b8db036b33d7b3648cb1f4ec827a53dc1a01b.1530465326.git.ren_guo@c-sky.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <860b8db036b33d7b3648cb1f4ec827a53dc1a01b.1530465326.git.ren_guo@c-sky.com> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 02, 2018 at 01:30:14AM +0800, Guo Ren wrote: > +#ifdef CONFIG_CPU_HAS_LDSTEX > +ENTRY(csky_cmpxchg) > + USPTOKSP > + mfcr a3, epc > + INCTRAP a3 > + > + subi sp, 8 > + stw a3, (sp, 0) > + mfcr a3, epsr > + stw a3, (sp, 4) > + > + psrset ee > +1: > + ldex a3, (a2) > + cmpne a0, a3 > + bt16 2f > + mov a3, a1 > + stex a3, (a2) > + bez a3, 1b > +2: > + sync.is > + mvc a0 > + ldw a3, (sp, 0) > + mtcr a3, epc > + ldw a3, (sp, 4) > + mtcr a3, epsr > + addi sp, 8 > + KSPTOUSP > + rte > +END(csky_cmpxchg) > +#else Please explain... if the CPU has LDEX/STEX, then _why_ do you need this?