Subject: Re: [PATCH] siimage: fix kernel oops on PPC 44x

From: Sergei Shtylyov <[email-masked]>
Date: Tue, 08 Apr 2008 17:09:57 +0400

Bartlomiej Zolnierkiewicz wrote:

>>Fix kernel oops due to machine check occuring in init_chipset_siimage() on PPC
>>44x platforms.  These 32-bit CPUs have 36-bit physical address and PCI I/O and
>>memory spaces are mapped beyond 4 GB; arch/ppc/ code has a fixup in ioremap()
>>that creates an illusion of the PCI I/O and memory resources being mapped below
>>4 GB, while arch/powerpc/ code got rid of this fixup with PPC 44x having instead
>>CONFIG_RESOURCES_64BIT=y -- this causes the resources to be truncated to 32-bit
>>'unsigned long' type in this driver, and so non-existant memory being ioremap'ed
>>and then accessed...

>>Thanks to Valentine Barshak for providing an initial patch and explanations.

>>Signed-off-by: Sergei Shtylyov <[email-masked]>

> applied and pushed to Linus, thanks!

> I guess that it would be worth to audit the rest of IDE code for

    Already done. Some drivers, like sgiioc4, scc_pata, and pmac are prone to
that at least in theory.  Although I doubt that they ever get used in such
environments as PPC 44x platform kernels, i.e. 32-bit kernel and PCI mapped 
beyond 4 GB.

> pci_resource_{start,end}() vs 'unsigned long' occurences and fix them.

    There are quite a lot of those overall but they only pose danger if the 
resource in question is in memory space since the I/O space always uses 
'unsigned long' addresses. So, IDE core and drivers using only I/O resources 
should not be prone to that kind of issue.

> [ Even if they work at the moment they are just bugs waiting to happened
>   when we add support for some new platforms or rewrite the code... ]

WBR, Sergei