Re: [PATCH] asm-generic: io: Fix ioport_map() for !CONFIG_GENERIC_IOMAP && CONFIG_INDIRECT_PIO

[Arnd Bergmann]

On Thu, Sep 13, 2018 at 2:48 PM Andrew Murray <andrew.murray@xxxxxxx> wrote:
>
> 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@xxxxxxx>
> Signed-off-by: Andrew Murray <andrew.murray@xxxxxxx>

Looks good to me,
Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>

Can you take this through the arm64 tree?