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=-7.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,NICE_REPLY_A, 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 290ACC48BE5 for ; Wed, 16 Jun 2021 18:53:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 08351613CB for ; Wed, 16 Jun 2021 18:53:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232147AbhFPSzH (ORCPT ); Wed, 16 Jun 2021 14:55:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:44704 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232006AbhFPSzF (ORCPT ); Wed, 16 Jun 2021 14:55:05 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id E38DA613B4; Wed, 16 Jun 2021 18:52:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1623869579; bh=Yqry3gXTN7L5llHGJ5LYioszkeOqgnImNugNlvlJamM=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=ZdUJ7KXNhkuKNAUX1x7Dbc4PeUFd1RBBDmKso0XmPrKjdsmddGAwUrigYr/JM82Wg QZYY1HboE2uqd3aDHbef4mKiID3gsuvm5EVze2dABZvbyZheNWkpSQusDL9vvTKeTZ llgpyzsvBgZGHBlVCUTvm9DEzi6Hvbi5dJZInB6zEXy5rjMxcXqZdGesyqHMQpTlGH 9vnvX5X6f8YAkbV0xff+6rjr3kuqkpugsrxF/ZBh7JF/BjFyZohG2TevhZq78dCe75 ZbfCX4ngCfJiMjfS5mqXkORZczgWyrHbvJC4IDDJol6JXrj9FBaLWKtCUNktRtFrtB Ewqj3p90Zv/OQ== Subject: Re: [PATCH 8/8] membarrier: Rewrite sync_core_before_usermode() and improve documentation To: Nicholas Piggin , x86@kernel.org Cc: Andrew Morton , Benjamin Herrenschmidt , Catalin Marinas , Dave Hansen , linux-arm-kernel@lists.infradead.org, LKML , linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, Mathieu Desnoyers , Michael Ellerman , Paul Mackerras , Peter Zijlstra , stable@vger.kernel.org, Will Deacon References: <07a8b963002cb955b7516e61bad19514a3acaa82.1623813516.git.luto@kernel.org> <1623818343.eko1v01gvr.astroid@bobo.none> From: Andy Lutomirski Message-ID: <1e248763-9372-6e4e-5dea-cda999000aeb@kernel.org> Date: Wed, 16 Jun 2021 11:52:58 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <1623818343.eko1v01gvr.astroid@bobo.none> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/15/21 9:45 PM, Nicholas Piggin wrote: > Excerpts from Andy Lutomirski's message of June 16, 2021 1:21 pm: >> The old sync_core_before_usermode() comments suggested that a non-icache-syncing >> return-to-usermode instruction is x86-specific and that all other >> architectures automatically notice cross-modified code on return to >> userspace. >> +/* >> + * XXX: can a powerpc person put an appropriate comment here? >> + */ >> +static inline void membarrier_sync_core_before_usermode(void) >> +{ >> +} >> + >> +#endif /* _ASM_POWERPC_SYNC_CORE_H */ > > powerpc's can just go in asm/membarrier.h $ ls arch/powerpc/include/asm/membarrier.h ls: cannot access 'arch/powerpc/include/asm/membarrier.h': No such file or directory > > /* > * The RFI family of instructions are context synchronising, and > * that is how we return to userspace, so nothing is required here. > */ Thanks!