[RFC V3 07/13] arm64/mm: Add FEAT_LPA2 specific encoding

[Anshuman Khandual]

On 10/12/21 4:11 PM, Suzuki K Poulose wrote:
> On 30/09/2021 11:35, Anshuman Khandual wrote:
>> FEAT_LPA2 requires different PTE representation formats for both 4K and 16K
>> page size config. This adds FEAT_LPA2 specific new PTE encodings as per ARM
>> ARM (0487G.A) which updates [pte|phys]_to_[phys|pte](). The updated helpers
>> would be used when FEAT_LPA2 gets enabled via CONFIG_ARM64_PA_BITS_52 on 4K
>> and 16K page size. Although TTBR encoding and phys_to_ttbr() helper remains
>> the same as FEAT_LPA for FEAT_LPA2 as well. It updates 'phys_to_pte' helper
>> to accept a temporary variable and changes impacted call sites.
>>
>> Signed-off-by: Anshuman Khandual <anshuman.khandual at arm.com>
>> ---
>>   arch/arm64/include/asm/assembler.h     | 14 +++++++++++---
>>   arch/arm64/include/asm/pgtable-hwdef.h |  4 ++++
>>   arch/arm64/include/asm/pgtable.h       |  4 ++++
>>   3 files changed, 19 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
>> index 3fbe04a..c1543067 100644
>> --- a/arch/arm64/include/asm/assembler.h
>> +++ b/arch/arm64/include/asm/assembler.h
>> @@ -628,6 +628,10 @@ alternative_endif
>>        */
>>       orr    \pte, \phys, \phys, lsr #36
>>       and    \pte, \pte, #PTE_ADDR_MASK
>> +#elif defined(CONFIG_ARM64_PA_BITS_52_LPA2)
>> +    orr    \pte, \phys, \phys, lsr #42
>> +    and    \pte, \pte, #PTE_ADDR_MASK | GENMASK(PAGE_SHIFT - 1, 10)
>> +    and    \pte, \pte, #~GENMASK(PAGE_SHIFT - 1, 10)
>>   #else  /* !CONFIG_ARM64_PA_BITS_52_LPA */
>>       mov    \pte, \phys
>>   #endif /* CONFIG_ARM64_PA_BITS_52_LPA */
>> @@ -635,9 +639,13 @@ alternative_endif
>>         .macro    pte_to_phys, phys, pte
>>   #ifdef CONFIG_ARM64_PA_BITS_52_LPA
>> -    ubfiz    \phys, \pte, #(48 - 16 - 12), #16
>> -    bfxil    \phys, \pte, #16, #32
>> -    lsl    \phys, \phys, #16
>> +    ubfiz    \phys, \pte, #(48 - PAGE_SHIFT - 12), #16
>> +    bfxil    \phys, \pte, #PAGE_SHIFT, #(48 - PAGE_SHIFT)
> 
> nit: This looks like an unrelated change and is better suited for the previous patch.

Changed the existing FEAT_LPA encodings here to use PAGE_SHIFT just
to match the new ones being added for FEAT_LPA2. But reasonable for
them to be folded into the previous patch instead.