linux-kernel - Re: [PATCH 1/2] x86: ioremap: fix wrong physical address handling

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Date:	Wed, 16 Jun 2010 20:50:52 -0600
From:	Matthew Wilcox <matthew@....cx>
To:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
Cc:	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
	macro@...ux-mips.org, kamezawa.hiroyu@...fujitsu.com,
	eike-kernel@...tec.de
Subject: Re: [PATCH 1/2] x86: ioremap: fix wrong physical address handling

On Thu, Jun 17, 2010 at 10:30:06AM +0900, Kenji Kaneshige wrote:
> Index: linux-2.6.34/arch/x86/mm/ioremap.c
> ===================================================================
> --- linux-2.6.34.orig/arch/x86/mm/ioremap.c	2010-06-15 04:43:00.978332015 +0900
> +++ linux-2.6.34/arch/x86/mm/ioremap.c	2010-06-15 05:32:59.291693007 +0900
> @@ -62,8 +62,8 @@
>  static void __iomem *__ioremap_caller(resource_size_t phys_addr,
>  		unsigned long size, unsigned long prot_val, void *caller)
>  {
> -	unsigned long pfn, offset, vaddr;
> -	resource_size_t last_addr;
> +	unsigned long offset, vaddr;
> +	resource_size_t pfn, last_pfn, last_addr;

I have a hard time understanding this change.  pfn is always a physical
address shifted by PAGE_SHIFT.  So a 32-bit pfn supports up to 44-bit
physical addresses.  Are your addresses above 44-bits?

> @@ -115,7 +113,7 @@
>  	 * Mappings have to be page-aligned
>  	 */
>  	offset = phys_addr & ~PAGE_MASK;
> -	phys_addr &= PAGE_MASK;
> +	phys_addr = (phys_addr >> PAGE_SHIFT) << PAGE_SHIFT;

I'd rather see PAGE_MASK fixed.  Would this work?

 #define PAGE_SIZE       (_AC(1,UL) << PAGE_SHIFT)
-#define PAGE_MASK       (~(PAGE_SIZE-1))
+#define PAGE_MASK       (~(PAGE_SIZE-1ULL))

-- 
Matthew Wilcox				Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."
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