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

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Date:	Thu, 17 Jun 2010 15:28:32 +0900
From:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
To:	Matthew Wilcox <matthew@....cx>
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

(2010/06/17 11:50), Matthew Wilcox wrote:
> 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))
>

I think it should work. But I'm worrying about regressions.
Now I think using PHYSICAL_PAGE_MASK (as my v.1 patch did) is good idea
again. What do you think about this?

Thanks,
Kenji Kaneshige

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