PCI: Fix pci_mmap_fits() for HAVE_PCI_RESOURCE_TO_USER platforms

commit 6bccc7f4 upstream.

In the PCI_MMAP_PROCFS case when the address being passed by the user is a
'user visible' resource address based on the bus window, and not the actual
contents of the resource, that's what we need to be checking it against.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/pci/pci-sysfs.c

@@ -772,15 +772,19 @@ void pci_remove_legacy_files(struct pci_bus *b)
 int pci_mmap_fits(struct pci_dev *pdev, int resno, struct vm_area_struct *vma,
 		  enum pci_mmap_api mmap_api)
 {
-	unsigned long nr, start, size, pci_start;
+	unsigned long nr, start, size;
+	resource_size_t pci_start = 0, pci_end;
 
 	if (pci_resource_len(pdev, resno) == 0)
 		return 0;
 	nr = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 	start = vma->vm_pgoff;
 	size = ((pci_resource_len(pdev, resno) - 1) >> PAGE_SHIFT) + 1;
-	pci_start = (mmap_api == PCI_MMAP_PROCFS) ?
-			pci_resource_start(pdev, resno) >> PAGE_SHIFT : 0;
+	if (mmap_api == PCI_MMAP_PROCFS) {
+		pci_resource_to_user(pdev, resno, &pdev->resource[resno],
+				     &pci_start, &pci_end);
+		pci_start >>= PAGE_SHIFT;
+	}
 	if (start >= pci_start && start < pci_start + size &&
 			start + nr <= pci_start + size)
 		return 1;