[PATCH 4.2.y-ckt 166/206] PCI: Supply CPU physical address (not bus address) to iomem_is_exclusive()

[Kamal Mostafa]

4.2.8-ckt12 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Bjorn Helgaas <bhelgaas at google.com>

commit ca620723d4ff9ea7ed484eab46264c3af871b9ae upstream.

iomem_is_exclusive() requires a CPU physical address, but on some arches we
supplied a PCI bus address instead.

On most arches, pci_resource_to_user(res) returns "res->start", which is a
CPU physical address.  But on microblaze, mips, powerpc, and sparc, it
returns the PCI bus address corresponding to "res->start".

The result is that pci_mmap_resource() may fail when it shouldn't (if the
bus address happens to match an existing resource), or it may succeed when
it should fail (if the resource is exclusive but the bus address doesn't
match it).

Call iomem_is_exclusive() with "res->start", which is always a CPU physical
address, not the result of pci_resource_to_user().

Fixes: e8de1481fd71 ("resource: allow MMIO exclusivity for device drivers")
Suggested-by: Yinghai Lu <yinghai at kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
CC: Arjan van de Ven <arjan at linux.intel.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/pci/pci-sysfs.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index eead54c..5f7cbea 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -1013,6 +1013,9 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
 	if (i >= PCI_ROM_RESOURCE)
 		return -ENODEV;
 
+	if (res->flags & IORESOURCE_MEM && iomem_is_exclusive(res->start))
+		return -EINVAL;
+
 	if (!pci_mmap_fits(pdev, i, vma, PCI_MMAP_SYSFS)) {
 		WARN(1, "process \"%s\" tried to map 0x%08lx bytes at page 0x%08lx on %s BAR %d (start 0x%16Lx, size 0x%16Lx)\n",
 			current->comm, vma->vm_end-vma->vm_start, vma->vm_pgoff,
@@ -1029,10 +1032,6 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
 	pci_resource_to_user(pdev, i, res, &start, &end);
 	vma->vm_pgoff += start >> PAGE_SHIFT;
 	mmap_type = res->flags & IORESOURCE_MEM ? pci_mmap_mem : pci_mmap_io;
-
-	if (res->flags & IORESOURCE_MEM && iomem_is_exclusive(start))
-		return -EINVAL;
-
 	return pci_mmap_page_range(pdev, vma, mmap_type, write_combine);
 }
 
-- 
2.7.4