linux-kernel - Re: [RFC v1 01/16] lib: devres: don't enclose pcim_*() functions in CONFIG_HAS

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Date:	Tue, 11 Dec 2012 16:55:45 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Cc:	Arnd Bergmann <arnd@...db.de>, Lior Amsalem <alior@...vell.com>,
	Andrew Lunn <andrew@...n.ch>,
	Yehuda Yitschak <yehuday@...vell.com>,
	Maen Suleiman <maen@...vell.com>,
	Jason Cooper <jason@...edaemon.net>,
	Tawfik Bayouk <tawfik@...vell.com>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...onic-design.de>,
	linux-kernel@...r.kernel.org,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Eran Ben-Avi <benavi@...vell.com>,
	Nadav Haklai <nadavh@...vell.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Shadi Ammouri <shadi@...vell.com>,
	Gregory Clement <gregory.clement@...e-electrons.com>,
	Yinghai Lu <yinghai@...nel.org>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC v1 01/16] lib: devres: don't enclose pcim_*() functions
	in CONFIG_HAS_IOPORT

On Tue, Dec 11, 2012 at 05:30:13PM +0100, Thomas Petazzoni wrote:
> arch/arm/mm/iomap.c is unconditionally compiled in all ARM kernels. And
> in this file, ioport_map() and ioport_unmap() are implement as soon as
> __io is defined. And basically, in arch/arm/include/asm/io.h, __io is
> defined for all platforms

Actually, I think that's a major bug in the single-zImage conversion:

#ifdef CONFIG_NEED_MACH_IO_H
#include <mach/io.h>
#elif defined(CONFIG_PCI)
#define IO_SPACE_LIMIT  ((resource_size_t)0xfffff)
#define __io(a)         __typesafe_io(PCI_IO_VIRT_BASE + ((a) & IO_SPACE_LIMIT))
#else
#define __io(a)         __typesafe_io((a) & IO_SPACE_LIMIT)
#endif

#ifndef IO_SPACE_LIMIT
#if defined(CONFIG_PCMCIA_SOC_COMMON) || defined(CONFIG_PCMCIA_SOC_COMMON_MODULE)
#define IO_SPACE_LIMIT ((resource_size_t)0xffffffff)
#elif defined(CONFIG_PCI) || defined(CONFIG_ISA) || defined(CONFIG_PCCARD)
#define IO_SPACE_LIMIT ((resource_size_t)0xffff)
#else
#define IO_SPACE_LIMIT ((resource_size_t)0)
#endif
#endif

So, in the !PCI !PCMCIA !ISA !PCCARD case, IO_SPACE_LIMIT will be zero,
which means the above common __io() functions will end up pointing the
access at the NULL pointer - whereas we shouldn't be providing IO space
support at all.  (Okay, there's a couple of corner cases we've known
about for a few _years_ but it's about time that stuff got fixed before
we try and put yet more band-aids over this.  Fix the root problems
guys, don't create more problems.)
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