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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 8DF66C433E6 for ; Sun, 14 Mar 2021 13:12:14 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id ED49B64E87 for ; Sun, 14 Mar 2021 13:12:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ED49B64E87 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=alpha.franken.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6C3786B0071; Sun, 14 Mar 2021 09:12:12 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 69A366B0072; Sun, 14 Mar 2021 09:12:12 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 527406B0073; Sun, 14 Mar 2021 09:12:12 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0208.hostedemail.com [216.40.44.208]) by kanga.kvack.org (Postfix) with ESMTP id 2413A6B0072 for ; Sun, 14 Mar 2021 09:12:12 -0400 (EDT) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id CFA5282499A8 for ; Sun, 14 Mar 2021 13:12:11 +0000 (UTC) X-FDA: 77918518062.25.529CDD7 Received: from elvis.franken.de (elvis.franken.de [193.175.24.41]) by imf02.hostedemail.com (Postfix) with ESMTP id 7053D407F8F4 for ; Sun, 14 Mar 2021 13:12:09 +0000 (UTC) Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1lLQXO-0007q5-01; Sun, 14 Mar 2021 14:12:06 +0100 Received: by alpha.franken.de (Postfix, from userid 1000) id B65E6C246C; Sun, 14 Mar 2021 14:09:00 +0100 (CET) Date: Sun, 14 Mar 2021 14:09:00 +0100 From: Thomas Bogendoerfer To: Huang Pei Cc: ambrosehua@gmail.com, Bibo Mao , linux-mips@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, Jiaxun Yang , Paul Burton , Li Xuefeng , Yang Tiezhu , Gao Juxin , Huacai Chen , Jinyang He Subject: Re: [PATCH] MIPS: clean up CONFIG_MIPS_PGD_C0_CONTEXT handling Message-ID: <20210314130900.GB5165@alpha.franken.de> References: <20210313013927.26733-1-huangpei@loongson.cn> <20210313013927.26733-2-huangpei@loongson.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210313013927.26733-2-huangpei@loongson.cn> User-Agent: Mutt/1.10.1 (2018-07-13) X-Stat-Signature: 7so3mayoepbromm8nb8593qaskkynf5u X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 7053D407F8F4 Received-SPF: none (alpha.franken.de>: No applicable sender policy available) receiver=imf02; identity=mailfrom; envelope-from=""; helo=elvis.franken.de; client-ip=193.175.24.41 X-HE-DKIM-Result: none/none X-HE-Tag: 1615727529-838838 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sat, Mar 13, 2021 at 09:39:27AM +0800, Huang Pei wrote: > +. LOONGSON64 use 0x98xx_xxxx_xxxx_xxxx as xphys cached, instread of > 0xa8xx_xxxx_xxxx_xxxx > > +. let CONFIG_MIPS_PGD_C0_CONTEXT depend on 64bit > > +. cast CAC_BASE into u64 to silence warning on MIPS32 > > CP0 Context has enough room for wraping pgd into its 41-bit PTEBase field. > > +. For XPHYS, the trick is that pgd is 4kB aligned, and the PABITS <= 53, > only save 53 - 12 = 41 bits, aka : > > bit[63:59] | 0000 00 | bit[53:12] | 0000 0000 0000 > > +. for CKSEG0, only save 29 - 12 = 17 bits > > when switching pgd, only need to save bit[53:12] or bit[28:12] into > CP0 Context's bit[63:23], see folling asm generated at run time > > tlbmiss_handler_setup_pgd: > .set push > .set noreorder > > dsra a2, a0, 29 > move a3, a0 > dins a0, zero, 29, 35 > daddiu a2, a2, 4 //for CKSEG0, a2 from 0xfffffffffffffffc > //into 0 > > movn a0, a3, a2 > dsll a0, a0, 11 > jr ra > dmtc0 a0, CP0_CONTEXT > > .set pop > > when using it on page walking > > dmfc0 k0, CP0_CONTEXT > dins k0, zero, 0, 23 // zero badv2 > ori k0, k0, (CAC_BASE >> 53) // *prefix* with bit[63:59] > drotr k0, k0, 11 // kick it in the right place > > Signed-off-by: Huang Pei > --- > arch/mips/Kconfig | 3 ++- > arch/mips/mm/tlbex.c | 9 +++++---- > 2 files changed, 7 insertions(+), 5 deletions(-) applied to mips-next. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]