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


Suzuki

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