PCI: Only allow WC mmap on prefetchable resources

commit cef4d02305a06be581bb7f4353446717a1b319ec upstream.

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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index 78802ee42878a5063ea274d5bd97b299e73bcca3..66c886365fbc637ed8a760b6ed46c7d97689e52b 100644 (file)
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -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)