- dead e-mail addresses (Zhichang, Gabriele)
On 13/09/2018 13:48, Andrew Murray wrote:
Hi Andrew,
The !CONFIG_GENERIC_IOMAP version of ioport_map uses MMIO_UPPER_LIMIT to
prevent users from making I/O accesses outside the expected I/O range -
however it erroneously treats MMIO_UPPER_LIMIT as a mask which is
contradictory to its other users.
The introduction of CONFIG_INDIRECT_PIO, which subtracts an arbitrary
amount from IO_SPACE_LIMIT to form MMIO_UPPER_LIMIT, results in ioport_map
mangling the given port rather than capping it.
We address this by aligning more closely with the CONFIG_GENERIC_IOMAP
implementation of ioport_map by using the comparison operator and
returning NULL where the port exceeds MMIO_UPPER_LIMIT. Though note that
we preserve the existing behavior of masking with IO_SPACE_LIMIT such that
we don't break existing buggy drivers that somehow rely on this masking.
I wouldn't say any drivers rely on this - for the only device driver
which uses the "Indirect" IO space region above MMIO_UPPER_LIMIT
(HiSilicon LPC), no child device driver for that host uses ioport_map()
[those being ipmi si and 8250 generic+of drivers].
Regardless of that, it seems better to return NULL when the port is
out-of-range, rather than masking it.
Cheers
Fixes: 5745392e0c2b ("PCI: Apply the new generic I/O management on PCI IO hosts")
Reported-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Andrew Murray <andrew.murray@xxxxxxx>
Reviewed-by: John Garry <john.garry@xxxxxxxxxx>
---
include/asm-generic/io.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
index 66d1d45..d356f80 100644
--- a/include/asm-generic/io.h
+++ b/include/asm-generic/io.h
@@ -1026,7 +1026,8 @@ static inline void __iomem *ioremap_wt(phys_addr_t offset, size_t size)
#define ioport_map ioport_map
static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)
{
- return PCI_IOBASE + (port & MMIO_UPPER_LIMIT);
+ port &= IO_SPACE_LIMIT;
+ return (port > MMIO_UPPER_LIMIT) ? NULL : PCI_IOBASE + port;
}
#endif
