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 88638C6778A for ; Thu, 5 Jul 2018 17:51:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 461B7240E8 for ; Thu, 5 Jul 2018 17:51:25 +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="tlD3WN8j" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 461B7240E8 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 S1753931AbeGERvW (ORCPT ); Thu, 5 Jul 2018 13:51:22 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:35178 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753442AbeGERvU (ORCPT ); Thu, 5 Jul 2018 13:51:20 -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=408ztwvdzfvqrsVveUms+H94Hq2HU4OMkU8nFC3XlPE=; b=tlD3WN8jRmFUkPmx9M1uQRrwg t9IGOUvAzItMfA5H6XnKGP9ERMMBwq/odF/mHSOl3BwcgEbApFjhO41YpaNZrjo3P0dnieCiYwNgN l+9ECIgNE0MNNLD5xGZXevaOQoBIXJoxA5RN91Gavbskg6bRJ+IYFrHUc6W1wFxQrvw2QMpDqNWbX B+Zymfa2pMxnE85NAmeubPXELr62w87papMNLef81HEFPovqt1T1JYktnDOdjxzktxXlbN21H8CFR Aimm6VbbQPvx16WQcuCjAzZpLZBi4pNEKtnRVnwU4PXCXeLEjiHEEV1UR0fUOl2napMqt+3EtjZEP KQAUzApCA==; 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 1fb8PF-0007Ht-4P; Thu, 05 Jul 2018 17:51:01 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8984F20289CF4; Thu, 5 Jul 2018 19:50:59 +0200 (CEST) Date: Thu, 5 Jul 2018 19:50:59 +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, Will Deacon Subject: Re: [PATCH V2 11/19] csky: Atomic operations Message-ID: <20180705175059.GE2530@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: > +#include > + > +#define __xchg(new, ptr, size) \ > +({ \ > + __typeof__(ptr) __ptr = (ptr); \ > + __typeof__(new) __new = (new); \ > + __typeof__(*(ptr)) __ret; \ > + unsigned long tmp; \ > + switch (size) { \ > + case 4: \ > + asm volatile ( \ > + "1: ldex.w %0, (%3) \n" \ > + " mov %1, %2 \n" \ > + " stex.w %1, (%3) \n" \ > + " bez %1, 1b \n" \ > + : "=&r" (__ret), "=&r" (tmp) \ > + : "r" (__new), "r"(__ptr) \ > + : "memory"); \ > + smp_mb(); \ > + break; \ > + default: \ > + BUILD_BUG(); \ > + } \ > + __ret; \ > +}) > + > +#define xchg(ptr, x) (__xchg((x), (ptr), sizeof(*(ptr)))) > + > +#define __cmpxchg(ptr, old, new, size) \ > +({ \ > + __typeof__(ptr) __ptr = (ptr); \ > + __typeof__(new) __new = (new); \ > + __typeof__(new) __tmp; \ > + __typeof__(old) __old = (old); \ > + __typeof__(*(ptr)) __ret; \ > + switch (size) { \ > + case 4: \ > + asm volatile ( \ > + "1: ldex.w %0, (%3) \n" \ > + " cmpne %0, %4 \n" \ > + " bt 2f \n" \ > + " mov %1, %2 \n" \ > + " stex.w %1, (%3) \n" \ > + " bez %1, 1b \n" \ > + "2: \n" \ > + : "=&r" (__ret), "=&r" (__tmp) \ > + : "r" (__new), "r"(__ptr), "r"(__old) \ > + : "memory"); \ > + smp_mb(); \ > + break; \ > + default: \ > + BUILD_BUG(); \ > + } \ > + __ret; \ > +}) > + > +#define cmpxchg(ptr, o, n) \ > + (__cmpxchg((ptr), (o), (n), sizeof(*(ptr)))) What's the memory ordering rules for your LDEX/STEX ? The mandated semantics for xchg() / cmpxchg() is an effective smp_mb() before _and_ after. The above implementation suggests LDEX implies a SYNC.IS, is this correct?