[PATCH -V5 11/13] arch/powerpc: properly isolate kernel and user proto-VSID

[Aneesh Kumar K.V]

Paul Mackerras <paulus at samba.org> writes:

> On Mon, Jul 30, 2012 at 04:52:17PM +0530, Aneesh Kumar K.V wrote:
>> From: "Aneesh Kumar K.V" <aneesh.kumar at linux.vnet.ibm.com>
>> 
>> The proto-VSID space is divided into two class
>> User:   0 to 2^(CONTEXT_BITS + USER_ESID_BITS) -1
>> kernel: 2^(CONTEXT_BITS + USER_ESID_BITS) to 2^(VSID_BITS) - 1
>> 
>> With KERNEL_START at 0xc000000000000000, the proto vsid for
>> the kernel ends up with 0xc00000000 (36 bits). With 64TB
>> patchset we need to have kernel proto-VSID in the
>> [2^37 to 2^38 - 1] range due to the increased USER_ESID_BITS.
>
> This needs to be rolled in with the previous patch, otherwise you'll
> break bisection.
>
>> diff --git a/arch/powerpc/mm/slb_low.S b/arch/powerpc/mm/slb_low.S
>> index db2cb3f..405d380 100644
>> --- a/arch/powerpc/mm/slb_low.S
>> +++ b/arch/powerpc/mm/slb_low.S
>> @@ -57,8 +57,16 @@ _GLOBAL(slb_allocate_realmode)
>>  _GLOBAL(slb_miss_kernel_load_linear)
>>  	li	r11,0
>>  BEGIN_FTR_SECTION
>> +	li	r9,0x1
>> +	rldimi  r10,r9,(CONTEXT_BITS + USER_ESID_BITS),0
>>  	b	slb_finish_load
>>  END_MMU_FTR_SECTION_IFCLR(MMU_FTR_1T_SEGMENT)
>> +	li	r9,0x1
>> +	/*
>> +	 * shift 12 bits less here, slb_finish_load_1T will do
>> +	 * the necessary shits
>> +	 */
>> +	rldimi  r10,r9,(CONTEXT_BITS + USER_ESID_BITS),0
>>  	b	slb_finish_load_1T
>
> Since you're actually doing exactly the same instructions in the 256M
> and 1T segment cases, why not do the li; rldimi before the
> BEGIN_FTR_SECTION?
>
>> @@ -86,8 +94,16 @@ _GLOBAL(slb_miss_kernel_load_vmemmap)
>>  	li	r11,0
>>  6:
>>  BEGIN_FTR_SECTION
>> +	li	r9,0x1
>> +	rldimi  r10,r9,(CONTEXT_BITS + USER_ESID_BITS),0
>>  	b	slb_finish_load
>>  END_MMU_FTR_SECTION_IFCLR(MMU_FTR_1T_SEGMENT)
>> +	li	r9,0x1
>> +	/*
>> +	 * shift 12 bits less here, slb_finish_load_1T will do
>> +	 * the necessary shits
>> +	 */
>> +	rldimi  r10,r9,(CONTEXT_BITS + USER_ESID_BITS),0
>>  	b	slb_finish_load_1T
>
> And similarly here.
>

Folded to the previous patch and updated

-aneesh