linux-kernel - Re: [PATCH] i386 pci: Handle mmaping 64bit bars.

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Message-ID: <m1hc2xa416.fsf@fess.ebiederm.org>
Date:	Fri, 13 Feb 2009 23:09:09 -0800
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i386 pci: Handle mmaping 64bit bars.

"H. Peter Anvin" <hpa@...or.com> writes:

> Eric W. Biederman wrote:
>> While reading through pci_mmap_page_range I realized that if don't
>> properly handle 64bit bars in the 32bit kernel.
>> 
>> Without the added cast the shift will be done in 32bit despite being
>> assigned to a 64bit variable and if we are mmaping an address above
>> 4G things will do the wrong thing.
>
> Hm... this really should be resource_size_t, no?
>
>> -	u64 addr = vma->vm_pgoff << PAGE_SHIFT;
>> +	u64 addr = ((u64)vma->vm_pgoff) << PAGE_SHIFT;

It is a parameter to the reserve_memtype and free_memtype functions,
which take a u64 so the type looks ok.

If I was going to quibble I would argue that those functions should
take a pfn instead of a u64...

Eric
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