asm-generic: io: Fix ioport_map() for !CONFIG_GENERIC_IOMAP && CONFIG_INDIRECT_PIO
authorAndrew Murray <andrew.murray@arm.com>
Thu, 13 Sep 2018 12:48:27 +0000 (13:48 +0100)
committerWill Deacon <will.deacon@arm.com>
Fri, 14 Sep 2018 08:49:21 +0000 (09:49 +0100)
commit500dd232449e7c07500e713dc6970aa713f8e4f1
treedc6b3eece9f99bccb2b4f1d573531c95c3acedf5
parent84c57dbd3c480fb2730c393a2cef994ddb4f42cc
asm-generic: io: Fix ioport_map() for !CONFIG_GENERIC_IOMAP && CONFIG_INDIRECT_PIO

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.

Fixes: 5745392e0c2b ("PCI: Apply the new generic I/O management on PCI IO hosts")
Reported-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
include/asm-generic/io.h