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From: Daniel Vetter <daniel.vetter@ffwll.ch>
To: DRI Development <dri-devel@lists.freedesktop.org>
Cc: "Intel Graphics Development" <intel-gfx@lists.freedesktop.org>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>,
	"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>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org, linux-media@vger.kernel.org,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	linux-pci@vger.kernel.org
Subject: [PATCH 44/65] PCI: Revoke mappings like devmem
Date: Fri, 23 Oct 2020 14:21:55 +0200
Message-ID: <20201023122216.2373294-44-daniel.vetter@ffwll.ch> (raw)
In-Reply-To: <20201023122216.2373294-1-daniel.vetter@ffwll.ch>

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.

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. The cleanest way is
to adjust this at at ->open time:

- for sysfs this is easy, now that binary attributes support this. We
  just set bin_attr->mapping when mmap is supported
- for procfs it's a bit more tricky, since procfs pci access has only
  one file per device, and access to a specific resources first needs
  to be set up with some ioctl calls. But mmap is only supported for
  the same resources as sysfs exposes with mmap support, and otherwise
  rejected, so we can set the mapping unconditionally at open time
  without harm.

A special consideration is for arch_can_pci_mmap_io() - we need to
make sure that the ->f_mapping doesn't alias between ioport and iomem
space. There's only 2 ways in-tree to support mmap of ioports: generic
pci mmap (ARCH_GENERIC_PCI_MMAP_RESOURCE), and sparc as the single
architecture hand-rolling. Both approach support ioport mmap through a
special pfn range and not through magic pte attributes. Aliasing is
therefore not a problem.

The only difference in access checks left is that sysfs PCI mmap does
not check for CAP_RAWIO. I'm not really sure whether that should be
added or not.

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kees Cook <keescook@chromium.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Jérôme Glisse <jglisse@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-mm@kvack.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-samsung-soc@vger.kernel.org
Cc: linux-media@vger.kernel.org
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-pci@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
--
v2:
- Totally new approach: Adjust filp->f_mapping at open time. Note that
  this now works on all architectures, not just those support
  ARCH_GENERIC_PCI_MMAP_RESOURCE
---
 drivers/pci/pci-sysfs.c | 4 ++++
 drivers/pci/proc.c      | 1 +
 2 files changed, 5 insertions(+)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 6d78df981d41..cee38fcb4a86 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -928,6 +928,7 @@ void pci_create_legacy_files(struct pci_bus *b)
 	b->legacy_io->read = pci_read_legacy_io;
 	b->legacy_io->write = pci_write_legacy_io;
 	b->legacy_io->mmap = pci_mmap_legacy_io;
+	b->legacy_io->mapping = iomem_get_mapping();
 	pci_adjust_legacy_attr(b, pci_mmap_io);
 	error = device_create_bin_file(&b->dev, b->legacy_io);
 	if (error)
@@ -940,6 +941,7 @@ void pci_create_legacy_files(struct pci_bus *b)
 	b->legacy_mem->size = 1024*1024;
 	b->legacy_mem->attr.mode = 0600;
 	b->legacy_mem->mmap = pci_mmap_legacy_mem;
+	b->legacy_io->mapping = iomem_get_mapping();
 	pci_adjust_legacy_attr(b, pci_mmap_mem);
 	error = device_create_bin_file(&b->dev, b->legacy_mem);
 	if (error)
@@ -1155,6 +1157,8 @@ static int pci_create_attr(struct pci_dev *pdev, int num, int write_combine)
 			res_attr->mmap = pci_mmap_resource_uc;
 		}
 	}
+	if (res_attr->mmap)
+		res_attr->mapping = iomem_get_mapping();
 	res_attr->attr.name = res_attr_name;
 	res_attr->attr.mode = 0600;
 	res_attr->size = pci_resource_len(pdev, num);
diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index 3a2f90beb4cb..9bab07302bbf 100644
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -298,6 +298,7 @@ static int proc_bus_pci_open(struct inode *inode, struct file *file)
 	fpriv->write_combine = 0;
 
 	file->private_data = fpriv;
+	file->f_mapping = iomem_get_mapping();
 
 	return 0;
 }
-- 
2.28.0


      parent reply index

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20201021163242.1458885-1-daniel.vetter@ffwll.ch>
     [not found] ` <20201023122216.2373294-1-daniel.vetter@ffwll.ch>
2020-10-23 12:21   ` [PATCH 05/65] drm/atomic-helper: Add dma-fence annotations Daniel Vetter
2020-10-23 12:21   ` [PATCH 06/65] drm/vkms: Annotate vblank timer Daniel Vetter
2020-10-23 12:21   ` [PATCH 07/65] drm/vblank: Annotate with dma-fence signalling section Daniel Vetter
2020-10-23 12:21   ` [PATCH 08/65] drm/amdgpu: add dma-fence annotations to atomic commit path Daniel Vetter
2020-10-23 12:21   ` [PATCH 17/65] drm/scheduler: use dma-fence annotations in main thread Daniel Vetter
2020-10-23 12:21   ` [PATCH 18/65] drm/amdgpu: use dma-fence annotations in cs_submit() Daniel Vetter
2020-10-23 12:21   ` [PATCH 19/65] drm/amdgpu: s/GFP_KERNEL/GFP_ATOMIC in scheduler code Daniel Vetter
2020-10-23 12:21   ` [PATCH 20/65] drm/scheduler: use dma-fence annotations in tdr work Daniel Vetter
2020-10-23 12:21   ` [PATCH 21/65] drm/amdgpu: use dma-fence annotations for gpu reset code Daniel Vetter
2020-10-23 12:21   ` [PATCH 22/65] Revert "drm/amdgpu: add fbdev suspend/resume on gpu reset" Daniel Vetter
2020-10-23 12:21   ` [PATCH 23/65] drm/i915: Annotate dma_fence_work Daniel Vetter
2020-10-23 12:21   ` [PATCH 29/65] s390/pci: Remove races against pte updates Daniel Vetter
2020-10-23 12:26     ` Daniel Vetter
2020-10-23 12:21   ` [PATCH 30/65] drm/exynos: Stop using frame_vector helpers Daniel Vetter
2020-10-23 12:21   ` [PATCH 31/65] drm/exynos: Use FOLL_LONGTERM for g2d cmdlists Daniel Vetter
2020-10-23 12:21   ` [PATCH 32/65] misc/habana: Stop using frame_vector helpers Daniel Vetter
2020-10-23 12:21   ` [PATCH 33/65] misc/habana: Use FOLL_LONGTERM for userptr Daniel Vetter
2020-10-23 12:21   ` [PATCH 34/65] mm/frame-vector: Use FOLL_LONGTERM Daniel Vetter
2020-10-23 12:21   ` [PATCH 35/65] media: videobuf2: Move frame_vector into media subsystem Daniel Vetter
2020-10-23 12:21   ` [PATCH 36/65] mm: Close race in generic_access_phys Daniel Vetter
2020-10-23 12:21   ` [PATCH 37/65] mm: Add unsafe_follow_pfn Daniel Vetter
2020-10-23 12:21   ` [PATCH 38/65] media/videbuf1|2: Mark follow_pfn usage as unsafe Daniel Vetter
2020-10-23 12:21   ` [PATCH 39/65] vfio/type1: Mark follow_pfn " Daniel Vetter
2020-10-23 12:21   ` [PATCH 40/65] PCI: Obey iomem restrictions for procfs mmap Daniel Vetter
2020-10-23 12:21   ` [PATCH 41/65] /dev/mem: Only set filp->f_mapping Daniel Vetter
2020-10-23 12:21   ` [PATCH 42/65] resource: Move devmem revoke code to resource framework Daniel Vetter
2020-10-23 12:21   ` [PATCH 43/65] sysfs: Support zapping of binary attr mmaps Daniel Vetter
2020-10-23 12:21   ` Daniel Vetter [this message]

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