PCI: Remove pci_mmap_page_range() wrapper

The ARCH_GENERIC_PCI_MMAP_RESOURCE symbol came up in a recent discussion,
and I noticed that this was left behind by an unfinished cleanup from 2017.

The only architecture that still relies on providing its own
pci_mmap_page_range() helper instead of using the generic
pci_mmap_resource_range() is sparc. Presumably the reasons for this have
not changed, but at least this can be simplified by converting sparc to use
the same interface as the others.

The only difference between the two is the device-specific offset that gets
added to or subtracted from vma->vm_pgoff.

Change the only caller of pci_mmap_page_range() in common code to subtract
this offset and call the modern interface, while adding it back in the
sparc implementation to preserve the existing behavior.

This removes the complexities of the dual interfaces from the common code,
and keeps it all specific to the sparc architecture code. According to
David Miller, the sparc code lets user space poke into the VGA I/O port
registers by mmapping the I/O space of the parent bridge device, which is
something that the generic pci_mmap_resource_range() code apparently does
not.

Link: https://lore.kernel.org/lkml/1519887203.622.3.camel@infradead.org/t/
Link: https://lore.kernel.org/lkml/20220714214657.2402250-3-shorne@gmail.com/
Link: https://lore.kernel.org/r/20220715153617.3393420-1-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Stafford Horne <shorne@gmail.com>

2 files changed, 6 insertions, 45 deletions

diff --git a/drivers/pci/mmap.c b/drivers/pci/mmap.c
index b8c9011987f4..4504039056d1 100644
--- a/drivers/pci/mmap.c
+++ b/drivers/pci/mmap.c
@@ -13,27 +13,6 @@
 
 #ifdef ARCH_GENERIC_PCI_MMAP_RESOURCE
 
-/*
- * Modern setup: generic pci_mmap_resource_range(), and implement the legacy
- * pci_mmap_page_range() (if needed) as a wrapper round it.
- */
-
-#ifdef HAVE_PCI_MMAP
-int pci_mmap_page_range(struct pci_dev *pdev, int bar,
-			struct vm_area_struct *vma,
-			enum pci_mmap_state mmap_state, int write_combine)
-{
-	resource_size_t start, end;
-
-	pci_resource_to_user(pdev, bar, &pdev->resource[bar], &start, &end);
-
-	/* Adjust vm_pgoff to be the offset within the resource */
-	vma->vm_pgoff -= start >> PAGE_SHIFT;
-	return pci_mmap_resource_range(pdev, bar, vma, mmap_state,
-				       write_combine);
-}
-#endif
-
 static const struct vm_operations_struct pci_phys_vm_ops = {
 #ifdef CONFIG_HAVE_IOREMAP_PROT
 	.access = generic_access_phys,
@@ -70,27 +49,4 @@ int pci_mmap_resource_range(struct pci_dev *pdev, int bar,
 				  vma->vm_page_prot);
 }
 
-#elif defined(HAVE_PCI_MMAP) /* && !ARCH_GENERIC_PCI_MMAP_RESOURCE */
-
-/*
- * Legacy setup: Implement pci_mmap_resource_range() as a wrapper around
- * the architecture's pci_mmap_page_range(), converting to "user visible"
- * addresses as necessary.
- */
-
-int pci_mmap_resource_range(struct pci_dev *pdev, int bar,
-			    struct vm_area_struct *vma,
-			    enum pci_mmap_state mmap_state, int write_combine)
-{
-	resource_size_t start, end;
-
-	/*
-	 * pci_mmap_page_range() expects the same kind of entry as coming
-	 * from /proc/bus/pci/ which is a "user visible" value. If this is
-	 * different from the resource itself, arch will do necessary fixup.
-	 */
-	pci_resource_to_user(pdev, bar, &pdev->resource[bar], &start, &end);
-	vma->vm_pgoff += start >> PAGE_SHIFT;
-	return pci_mmap_page_range(pdev, bar, vma, mmap_state, write_combine);
-}
 #endif
diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index 31b26d8ea6cc..f967709082d6 100644
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -244,6 +244,7 @@ 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;
+	resource_size_t start, end;
 	int i, ret, write_combine = 0, res_bit = IORESOURCE_MEM;
 
 	if (!capable(CAP_SYS_RAWIO) ||
@@ -278,7 +279,11 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma)
 	    iomem_is_exclusive(dev->resource[i].start))
 		return -EINVAL;
 
-	ret = pci_mmap_page_range(dev, i, vma,
+	pci_resource_to_user(dev, i, &dev->resource[i], &start, &end);
+
+	/* Adjust vm_pgoff to be the offset within the resource */
+	vma->vm_pgoff -= start >> PAGE_SHIFT;
+	ret = pci_mmap_resource_range(dev, i, vma,
 				  fpriv->mmap_state, write_combine);
 	if (ret < 0)
 		return ret;