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=-4.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 A6D30C4363C for ; Wed, 7 Oct 2020 18:41:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4634C2173E for ; Wed, 7 Oct 2020 18:41:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602096096; bh=jybj9lxB9HDSUiFTDfX0tbqIYHCI2WD8V2Srcj/Y2q0=; h=Date:From:To:Cc:Subject:In-Reply-To:List-ID:From; b=K+R7vA9H68OlPaM5zU5Nkk5UEK32xBgAizhxmyooj4uL3WlwNPGcPRlRnlXbjfIdS AgJbPvXJ7BgmFR7+8BbXxKSq3wEYFNau9UnGqiRGWjf1NHLfb9ibocCuut3zFS5x8x K37/kX/BZfQKNYDJIFNd+OLyIH2hoGcSfIOamYFU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727772AbgJGSlf (ORCPT ); Wed, 7 Oct 2020 14:41:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:47980 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726197AbgJGSle (ORCPT ); Wed, 7 Oct 2020 14:41:34 -0400 Received: from localhost (170.sub-72-107-125.myvzw.com [72.107.125.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7E5DE2168B; Wed, 7 Oct 2020 18:41:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1602096093; bh=jybj9lxB9HDSUiFTDfX0tbqIYHCI2WD8V2Srcj/Y2q0=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=fvTSDoaSFaR5f+GW+1VfPgc/eLGyZstXFPM0Pbbd72KBA+ecoTEtBddTdYZhtlYj3 bsFSSKkvJi72PjhGp9tmM7ZEtUUSjRP9PU6yME2u3FWvCct89TVsvj/po3TnsMWfeR J1+3vx2h0ip+tE/J1MK3LQud3yRzf+O7RxgCuZrk= Date: Wed, 7 Oct 2020 13:41:31 -0500 From: Bjorn Helgaas To: Daniel Vetter Cc: DRI Development , LKML , kvm@vger.kernel.org, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org, linux-s390@vger.kernel.org, Daniel Vetter , Jason Gunthorpe , Kees Cook , Dan Williams , Andrew Morton , John Hubbard , =?iso-8859-1?B?Suly9G1l?= Glisse , Jan Kara , Bjorn Helgaas , linux-pci@vger.kernel.org Subject: Re: [PATCH 10/13] PCI: revoke mappings like devmem Message-ID: <20201007184131.GA3259154@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201007164426.1812530-11-daniel.vetter@ffwll.ch> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Capitalize subject, like other patches in this series and previous drivers/pci history. On Wed, Oct 07, 2020 at 06:44:23PM +0200, Daniel Vetter wrote: > Since 3234ac664a87 ("/dev/mem: Revoke mappings when a driver claims > the region") /dev/kmem zaps ptes when the kernel requests exclusive > acccess to an iomem region. And with CONFIG_IO_STRICT_DEVMEM, this is > the default for all driver uses. > > Except there's two more ways to access pci bars: sysfs and proc mmap > support. Let's plug that hole. s/pci/PCI/ in commit logs and comments. > For revoke_devmem() to work we need to link our vma into the same > address_space, with consistent vma->vm_pgoff. ->pgoff is already > adjusted, because that's how (io_)remap_pfn_range works, but for the > mapping we need to adjust vma->vm_file->f_mapping. Usually that's done > at ->open time, but that's a bit tricky here with all the entry points > and arch code. So instead create a fake file and adjust vma->vm_file. > > Note this only works for ARCH_GENERIC_PCI_MMAP_RESOURCE. But that > seems to be a subset of architectures support STRICT_DEVMEM, so we > should be good. > > The only difference in access checks left is that sysfs pci mmap does > not check for CAP_RAWIO. But I think that makes some sense compared to > /dev/mem and proc, where one file gives you access to everything and > no ownership applies. > --- a/drivers/char/mem.c > +++ b/drivers/char/mem.c > @@ -810,6 +810,7 @@ static loff_t memory_lseek(struct file *file, loff_t offset, int orig) > } > > static struct inode *devmem_inode; > +static struct vfsmount *devmem_vfs_mount; > > #ifdef CONFIG_IO_STRICT_DEVMEM > void revoke_devmem(struct resource *res) > @@ -843,6 +844,20 @@ void revoke_devmem(struct resource *res) > > unmap_mapping_range(inode->i_mapping, res->start, resource_size(res), 1); > } > + > +struct file *devmem_getfile(void) > +{ > + struct file *file; > + > + file = alloc_file_pseudo(devmem_inode, devmem_vfs_mount, "devmem", > + O_RDWR, &kmem_fops); > + if (IS_ERR(file)) > + return NULL; > + > + file->f_mapping = devmem_indoe->i_mapping; "devmem_indoe"? Obviously not compiled, I guess? > --- a/include/linux/ioport.h > +++ b/include/linux/ioport.h > @@ -304,8 +304,10 @@ struct resource *request_free_mem_region(struct resource *base, > > #ifdef CONFIG_IO_STRICT_DEVMEM > void revoke_devmem(struct resource *res); > +struct file *devm_getfile(void); > #else > static inline void revoke_devmem(struct resource *res) { }; > +static inline struct file *devmem_getfile(void) { return NULL; }; I guess these names are supposed to match? > #endif > > #endif /* __ASSEMBLY__ */ > -- > 2.28.0 >