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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: 5745392e0c ("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>
This commit is contained in:
Andrew Murray 2018-09-13 13:48:27 +01:00 committed by Will Deacon
parent 84c57dbd3c
commit 500dd23244
1 changed files with 2 additions and 1 deletions
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3
include/asm-generic/io.h
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@ -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