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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E89C1C433F5 for ; Thu, 4 Nov 2021 12:18:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CEA6460FE3 for ; Thu, 4 Nov 2021 12:18:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231402AbhKDMVQ (ORCPT ); Thu, 4 Nov 2021 08:21:16 -0400 Received: from mailgw01.mediatek.com ([60.244.123.138]:33270 "EHLO mailgw01.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S229843AbhKDMVO (ORCPT ); Thu, 4 Nov 2021 08:21:14 -0400 X-UUID: 731cec951b914e8b9b791b1b4e1d014f-20211104 X-UUID: 731cec951b914e8b9b791b1b4e1d014f-20211104 Received: from mtkmbs10n1.mediatek.inc [(172.21.101.34)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 1409694579; Thu, 04 Nov 2021 20:18:34 +0800 Received: from mtkmbs10n2.mediatek.inc (172.21.101.183) by mtkmbs10n2.mediatek.inc (172.21.101.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.3; Thu, 4 Nov 2021 20:18:33 +0800 Received: from mtksdccf07 (172.21.84.99) by mtkmbs10n2.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.3 via Frontend Transport; Thu, 4 Nov 2021 20:18:33 +0800 Message-ID: Subject: Re: [PATCH v2] dma-direct: improve DMA_ATTR_NO_KERNEL_MAPPING From: Walter Wu To: Christoph Hellwig CC: Marek Szyprowski , Robin Murphy , Matthias Brugger , "Ard Biesheuvel" , Andrew Morton , , , , wsd_upstream , Date: Thu, 4 Nov 2021 20:18:33 +0800 In-Reply-To: <20211104085336.GA24260@lst.de> References: <20211104023221.16391-1-walter-zh.wu@mediatek.com> <20211104085336.GA24260@lst.de> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2021-11-04 at 09:53 +0100, Christoph Hellwig wrote: > On Thu, Nov 04, 2021 at 10:32:21AM +0800, Walter Wu wrote: > > diff --git a/include/linux/set_memory.h > > b/include/linux/set_memory.h > > index f36be5166c19..6c7d1683339c 100644 > > --- a/include/linux/set_memory.h > > +++ b/include/linux/set_memory.h > > @@ -7,11 +7,16 @@ > > > > #ifdef CONFIG_ARCH_HAS_SET_MEMORY > > #include > > + > > +#ifndef CONFIG_RODATA_FULL_DEFAULT_ENABLED > > This is an arm64-specific symbol, and one that only controls a > default. I don't think it is suitable to key off stubs in common > code. > ok > > +static inline int set_memory_valid(unsigned long addr, int > > numpages, int enable) { return 0; } > > Pleae avoid overly long lines. > > > + if (IS_ENABLED(CONFIG_RODATA_FULL_DEFAULT_ENABLED)) { > > + kaddr = (unsigned > > long)phys_to_virt(dma_to_phys(dev, *dma_handle)); > > This can just use page_address. > > > + /* page remove kernel mapping for arm64 */ > > + set_memory_valid(kaddr, size >> PAGE_SHIFT, 0); > > + } > > But more importantly: set_memory_valid only exists on arm64, this > will break compile everywhere else. And this API is complete crap. > Passing kernel virtual addresses as unsigned long just sucks, and > passing an integer argument for valid/non-valid also is a horrible > API. > Would you think __kernel_map_page() is ok? Many arch support it, and only pass page and page number. but need to depend CONFIG_DEBUG_PAGEALLOC. Thanks. Walter > Not to mention the overly long line. Same on the free side.