Subject: Re: [PATCH V4 07/18] powerpc/mm: Update masked bits for linux page table

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Fri, 26 Feb 2016 07:38:57 +0530

Paul Mackerras <[email-masked]> writes:

> On Tue, Feb 23, 2016 at 10:18:09AM +0530, Aneesh Kumar K.V wrote:
>> We now use physical address in upper page table tree levels. Even though
>> they are aligned to their size, for the masked bits we use the
>> overloaded bit positions as per PowerISA 3.0. We keep the bad bits check
>> as it is, and will use conditional there when adding radix. Bad bits
>> check also check for reserved bits and we oveload some of the reserved
>> fields of radix in hash config.
>> 
>> Signed-off-by: Aneesh Kumar K.V <[email-masked]>
>> ---
>>  arch/powerpc/include/asm/book3s/64/hash-64k.h | 15 ++++++---------
>>  1 file changed, 6 insertions(+), 9 deletions(-)
>> 
>> diff --git a/arch/powerpc/include/asm/book3s/64/hash-64k.h b/arch/powerpc/include/asm/book3s/64/hash-64k.h
>> index f0f5f91d7909..60c2c912c3a7 100644
>> --- a/arch/powerpc/include/asm/book3s/64/hash-64k.h
>> +++ b/arch/powerpc/include/asm/book3s/64/hash-64k.h
>> @@ -60,15 +60,12 @@
>>  #define PTE_FRAG_SIZE_SHIFT  12
>>  #define PTE_FRAG_SIZE (1UL << PTE_FRAG_SIZE_SHIFT)
>>  
>> -/*
>> - * Bits to mask out from a PMD to get to the PTE page
>> - * PMDs point to PTE table fragments which are PTE_FRAG_SIZE aligned.
>> - */
>> -#define PMD_MASKED_BITS		(PTE_FRAG_SIZE - 1)
>> -/* Bits to mask out from a PGD/PUD to get to the PMD page */
>> -#define PUD_MASKED_BITS		0x1ff
>> -/* FIXME!! Will be fixed in next patch */
>> -#define PGD_MASKED_BITS		0
>> +/* Bits to mask out from a PMD to get to the PTE page */
>> +#define PMD_MASKED_BITS		0xc0000000000000ffUL
>> +/* Bits to mask out from a PUD to get to the PMD page */
>> +#define PUD_MASKED_BITS		0xc0000000000000ffUL
>> +/* Bits to mask out from a PGD to get to the PUD page */
>> +#define PGD_MASKED_BITS		0xc0000000000000ffUL
>
> Why not fold this into the previous patch?  (and include this patch's
> commentary in the previous patch's commentary, of course)
>

Ok will do that. I was trying to make sure the change is called out
separately.

-aneesh