From: David Laight <David.Laight@ACULAB.COM>
To: 'Niklas Schnelle' <schnelle@linux.ibm.com>,
Arnd Bergmann <arnd@arndb.de>, Vineet Gupta <vgupta@synopsys.com>,
"David S. Miller" <davem@davemloft.net>
Cc: Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
"clang-built-linux@googlegroups.com"
<clang-built-linux@googlegroups.com>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
"linux-snps-arc@lists.infradead.org"
<linux-snps-arc@lists.infradead.org>,
"sparclinux@vger.kernel.org" <sparclinux@vger.kernel.org>
Subject: RE: [PATCH v3 3/3] asm-generic/io.h: Silence -Wnull-pointer-arithmetic warning on PCI_IOBASE
Date: Wed, 21 Apr 2021 11:24:47 +0000 [thread overview]
Message-ID: <bb21141706d7477794453f7f52f6bc98@AcuMS.aculab.com> (raw)
In-Reply-To: <20210421111759.2059976-4-schnelle@linux.ibm.com>
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
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2021-04-21 11:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-21 11:17 [PATCH v3 0/3] asm-generic/io.h: Silence -Wnull-pointer-arithmetic warning on PCI_IOBASE Niklas Schnelle
2021-04-21 11:17 ` [PATCH v3 1/3] sparc: explicitly set PCI_IOBASE to 0 Niklas Schnelle
2021-04-21 11:17 ` [PATCH v3 2/3] ARC: io.h: Include asm/bug.h Niklas Schnelle
2021-04-21 11:17 ` [PATCH v3 3/3] asm-generic/io.h: Silence -Wnull-pointer-arithmetic warning on PCI_IOBASE Niklas Schnelle
2021-04-21 11:24 ` David Laight [this message]
2021-04-21 11:50 ` Niklas Schnelle
2021-04-21 11:57 ` Arnd Bergmann
2021-04-21 15:19 ` kernel test robot
2021-04-21 15:38 ` Niklas Schnelle
2021-04-21 16:59 ` kernel test robot
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