Messages in this thread | | | Subject | Re: [PATCH] asm-generic: io: Fix ioport_map() for !CONFIG_GENERIC_IOMAP && CONFIG_INDIRECT_PIO | From | John Garry <> | Date | Mon, 17 Sep 2018 15:42:32 +0100 |
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- 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@arm.com> > Signed-off-by: Andrew Murray <andrew.murray@arm.com>
Reviewed-by: John Garry <john.garry@huawei.com>
> --- > 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 > >
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