linux-kernel - Re: [PATCH] arm64/mm: Use phys_to

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Date:   Tue, 28 Apr 2020 09:45:32 +1000
From:   Gavin Shan <gshan@...hat.com>
To:     Mark Rutland <mark.rutland@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        catalin.marinas@....com, will@...nel.org, shan.gavin@...il.com
Subject: Re: [PATCH] arm64/mm: Use phys_to_page() to access pgtable memory

Hi Mark,

On 4/24/20 7:22 PM, Mark Rutland wrote:
> On Fri, Apr 24, 2020 at 02:48:54PM +1000, Gavin Shan wrote:
>> The macros {pgd, pud, pmd}_page() retrieves the page struct of the
>> corresponding page frame, which is reserved as page table. There
>> is already a macro (phys_to_page), defined in memory.h, to convert
>> the physical address to the page struct. So it's reasonable to
>> use that in pgtable.h.
>>
>> Signed-off-by: Gavin Shan <gshan@...hat.com>
> 
> It might be worth pointing out that phys_to_page() is defined as:
> 
> #define phys_to_page(phys)      (pfn_to_page(__phys_to_pfn(phys)))
> 
> ... so this is obviously equivalent.
> 
> Given that, and given we already explicitly include <asm/memory.h>, this
> looks like a nice cleanup to me.
> 
> With or without the commit message addition:
> 
> Reviewed-by: Mark Rutland <mark.rutland@....com>
> 
> Mark.
> 

Thanks for the comments. I will post v2 shortly, which has the improved
commit log and your reviewed-by.

Thanks,
Gavin

>> ---
>>   arch/arm64/include/asm/pgtable.h | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
>> index 538c85e62f86..8c20e2bd6287 100644
>> --- a/arch/arm64/include/asm/pgtable.h
>> +++ b/arch/arm64/include/asm/pgtable.h
>> @@ -508,7 +508,7 @@ static inline void pte_unmap(pte_t *pte) { }
>>   #define pte_set_fixmap_offset(pmd, addr)	pte_set_fixmap(pte_offset_phys(pmd, addr))
>>   #define pte_clear_fixmap()		clear_fixmap(FIX_PTE)
>>   
>> -#define pmd_page(pmd)		pfn_to_page(__phys_to_pfn(__pmd_to_phys(pmd)))
>> +#define pmd_page(pmd)			phys_to_page(__pmd_to_phys(pmd))
>>   
>>   /* use ONLY for statically allocated translation tables */
>>   #define pte_offset_kimg(dir,addr)	((pte_t *)__phys_to_kimg(pte_offset_phys((dir), (addr))))
>> @@ -566,7 +566,7 @@ static inline phys_addr_t pud_page_paddr(pud_t pud)
>>   #define pmd_set_fixmap_offset(pud, addr)	pmd_set_fixmap(pmd_offset_phys(pud, addr))
>>   #define pmd_clear_fixmap()		clear_fixmap(FIX_PMD)
>>   
>> -#define pud_page(pud)		pfn_to_page(__phys_to_pfn(__pud_to_phys(pud)))
>> +#define pud_page(pud)			phys_to_page(__pud_to_phys(pud))
>>   
>>   /* use ONLY for statically allocated translation tables */
>>   #define pmd_offset_kimg(dir,addr)	((pmd_t *)__phys_to_kimg(pmd_offset_phys((dir), (addr))))
>> @@ -624,7 +624,7 @@ static inline phys_addr_t pgd_page_paddr(pgd_t pgd)
>>   #define pud_set_fixmap_offset(pgd, addr)	pud_set_fixmap(pud_offset_phys(pgd, addr))
>>   #define pud_clear_fixmap()		clear_fixmap(FIX_PUD)
>>   
>> -#define pgd_page(pgd)		pfn_to_page(__phys_to_pfn(__pgd_to_phys(pgd)))
>> +#define pgd_page(pgd)			phys_to_page(__pgd_to_phys(pgd))
>>   
>>   /* use ONLY for statically allocated translation tables */
>>   #define pud_offset_kimg(dir,addr)	((pud_t *)__phys_to_kimg(pud_offset_phys((dir), (addr))))
>> -- 
>> 2.23.0
>>
>