From: Niklas Schnelle
> Sent: 21 April 2021 12:18
>
> When PCI_IOBASE is not defined, it is set to 0 such that it is ignored
> in calls to the readX/writeX primitives. This triggers clang's
> -Wnull-pointer-arithmetic warning and will result in illegal accesses on
> platforms that do not support I/O ports if drivers do still attempt to
> access them.
>
> Make things explicit and silence the warning by letting inb() and
> friends fail with WARN_ONCE() and a 0xff... return in case PCI_IOBASE is
> not defined.
...
>
> diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
> index c6af40ce03be..aabb0a8186ee 100644
> --- a/include/asm-generic/io.h
> +++ b/include/asm-generic/io.h
...
> @@ -458,12 +454,17 @@ static inline void writesq(volatile void __iomem *addr,
> const void *buffer,
> #define _inb _inb
> static inline u8 _inb(unsigned long addr)
> {
> +#ifdef PCI_IOBASE
> u8 val;
>
> __io_pbr();
> val = __raw_readb(PCI_IOBASE + addr);
> __io_par(val);
> return val;
> +#else
> + WARN_ONCE(1, "No I/O port support\n");
> + return ~0;
> +#endif
> }
> #endif
I suspect that this might be better not inlined
when PCI_IOBASE is undefined.
Otherwise you get quite a lot of bloat from all the
WARN_ONCE() calls.
David
-
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