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PCI: Only allow WC mmap on prefetchable resources

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The /proc/bus/pci mmap interface allows the user to specify whether they
want WC or not.  Don't let them do so on non-prefetchable BARs.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org
This commit is contained in:
David Woodhouse 2017-04-12 13:25:52 +01:00 committed by Bjorn Helgaas
parent 17caf56731
commit cef4d02305
1 changed files with 8 additions and 5 deletions
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13
drivers/pci/proc.c
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@ -231,7 +231,7 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma)
{
struct pci_dev *dev = PDE_DATA(file_inode(file));
struct pci_filp_private *fpriv = file->private_data;
int i, ret, write_combine, res_bit;
int i, ret, write_combine = 0, res_bit;
if (!capable(CAP_SYS_RAWIO))
return -EPERM;
@ -251,10 +251,13 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma)
if (i >= PCI_ROM_RESOURCE)
return -ENODEV;
if (fpriv->mmap_state == pci_mmap_mem)
write_combine = fpriv->write_combine;
else
write_combine = 0;
if (fpriv->mmap_state == pci_mmap_mem &&
fpriv->write_combine) {
if (dev->resource[i].flags & IORESOURCE_PREFETCH)
write_combine = 1;
else
return -EINVAL;
}
ret = pci_mmap_page_range(dev, vma,
fpriv->mmap_state, write_combine);
if (ret < 0)