From: Bjorn Helgaas <helgaas@kernel.org>
To: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "DRI Development" <dri-devel@lists.freedesktop.org>,
LKML <linux-kernel@vger.kernel.org>,
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" <daniel.vetter@intel.com>,
"Jason Gunthorpe" <jgg@ziepe.ca>,
"Kees Cook" <keescook@chromium.org>,
"Dan Williams" <dan.j.williams@intel.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"John Hubbard" <jhubbard@nvidia.com>,
"Jérôme Glisse" <jglisse@redhat.com>, "Jan Kara" <jack@suse.cz>,
"Bjorn Helgaas" <bhelgaas@google.com>,
linux-pci@vger.kernel.org
Subject: Re: [PATCH 10/13] PCI: revoke mappings like devmem
Date: Wed, 7 Oct 2020 13:41:31 -0500 [thread overview]
Message-ID: <20201007184131.GA3259154@bjorn-Precision-5520> (raw)
In-Reply-To: <20201007164426.1812530-11-daniel.vetter@ffwll.ch>
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
>
next prev parent reply other threads:[~2020-10-07 18:41 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20201007164426.1812530-1-daniel.vetter@ffwll.ch>
2020-10-07 16:44 ` [PATCH 09/13] PCI: obey iomem restrictions for procfs mmap Daniel Vetter
2020-10-07 18:46 ` Bjorn Helgaas
2020-10-07 16:44 ` [PATCH 10/13] PCI: revoke mappings like devmem Daniel Vetter
2020-10-07 18:41 ` Bjorn Helgaas [this message]
2020-10-07 19:24 ` Daniel Vetter
2020-10-07 19:33 ` Dan Williams
2020-10-07 19:47 ` Daniel Vetter
2020-10-07 22:23 ` Dan Williams
2020-10-07 22:29 ` Dan Williams
2020-10-08 8:09 ` Daniel Vetter
2020-10-07 23:24 ` Jason Gunthorpe
2020-10-08 7:31 ` Daniel Vetter
2020-10-08 7:49 ` Dan Williams
2020-10-08 8:13 ` Daniel Vetter
2020-10-08 8:35 ` Dan Williams
2020-10-08 12:41 ` Jason Gunthorpe
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201007184131.GA3259154@bjorn-Precision-5520 \
--to=helgaas@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=bhelgaas@google.com \
--cc=dan.j.williams@intel.com \
--cc=daniel.vetter@ffwll.ch \
--cc=daniel.vetter@intel.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=jack@suse.cz \
--cc=jgg@ziepe.ca \
--cc=jglisse@redhat.com \
--cc=jhubbard@nvidia.com \
--cc=keescook@chromium.org \
--cc=kvm@vger.kernel.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-pci@vger.kernel.org \
--cc=linux-s390@vger.kernel.org \
--cc=linux-samsung-soc@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).