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Date: Fri, 13 Feb 2009 22:17:13 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: "Eric W. Biederman" <ebiederm@xmission.com>
CC: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH] i386 pci: Handle mmaping 64bit bars.
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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;

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.