[PATCH 3.16 261/366] MIPS: Fix off-by-one in pci_resource_to_user()

[Ben Hutchings]

3.16.61-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Paul Burton <paul.burton@xxxxxxxx>

commit 38c0a74fe06da3be133cae3fb7bde6a9438e698b upstream.

The MIPS implementation of pci_resource_to_user() introduced in v3.12 by
commit 4c2924b725fb ("MIPS: PCI: Use pci_resource_to_user to map pci
memory space properly") incorrectly sets *end to the address of the
byte after the resource, rather than the last byte of the resource.

This results in userland seeing resources as a byte larger than they
actually are, for example a 32 byte BAR will be reported by a tool such
as lspci as being 33 bytes in size:

    Region 2: I/O ports at 1000 [disabled] [size=33]

Correct this by subtracting one from the calculated end address,
reporting the correct address to userland.

Signed-off-by: Paul Burton <paul.burton@xxxxxxxx>
Reported-by: Rui Wang <rui.wang@xxxxxxxxxxxxx>
Fixes: 4c2924b725fb ("MIPS: PCI: Use pci_resource_to_user to map pci memory space properly")
Cc: James Hogan <jhogan@xxxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Cc: Wolfgang Grandegger <wg@xxxxxxxxxxxxxx>
Cc: linux-mips@xxxxxxxxxxxxxx
Patchwork: https://patchwork.linux-mips.org/patch/19829/
[bwh: Backported to 3.16: adjust filename]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 arch/mips/include/asm/pci.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/mips/include/asm/pci.h
+++ b/arch/mips/include/asm/pci.h
@@ -87,7 +87,7 @@ static inline void pci_resource_to_user(
 	phys_t size = resource_size(rsrc);
 
 	*start = fixup_bigphys_addr(rsrc->start, size);
-	*end = rsrc->start + size;
+	*end = rsrc->start + size - 1;
 }
 
 /*