Messages in this thread | | | Date | Tue, 30 Apr 2024 13:37:53 +0200 | Subject | Re: [PATCH v2 1/3] arm64/mm: Refactor PMD_PRESENT_INVALID and PTE_PROT_NONE bits | From | David Hildenbrand <> |
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On 30.04.24 13:11, Catalin Marinas wrote: > On Mon, Apr 29, 2024 at 06:15:45PM +0100, Ryan Roberts wrote: >> On 29/04/2024 17:20, Catalin Marinas wrote: >>> On Mon, Apr 29, 2024 at 03:02:05PM +0100, Ryan Roberts wrote: >>>> diff --git a/arch/arm64/include/asm/pgtable-prot.h b/arch/arm64/include/asm/pgtable-prot.h >>>> index dd9ee67d1d87..de62e6881154 100644 >>>> --- a/arch/arm64/include/asm/pgtable-prot.h >>>> +++ b/arch/arm64/include/asm/pgtable-prot.h >>>> @@ -18,14 +18,7 @@ >>>> #define PTE_DIRTY (_AT(pteval_t, 1) << 55) >>>> #define PTE_SPECIAL (_AT(pteval_t, 1) << 56) >>>> #define PTE_DEVMAP (_AT(pteval_t, 1) << 57) >>>> -#define PTE_PROT_NONE (_AT(pteval_t, 1) << 58) /* only when !PTE_VALID */ >>>> - >>>> -/* >>>> - * This bit indicates that the entry is present i.e. pmd_page() >>>> - * still points to a valid huge page in memory even if the pmd >>>> - * has been invalidated. >>>> - */ >>>> -#define PMD_PRESENT_INVALID (_AT(pteval_t, 1) << 59) /* only when !PMD_SECT_VALID */ >>>> +#define PTE_INVALID (_AT(pteval_t, 1) << 59) /* only when !PTE_VALID */ >>> >>> Nitpick - I prefer the PTE_PRESENT_INVALID name as it makes it clearer >>> it's a present pte. We already have PTE_VALID, calling it PTE_INVALID >>> looks like a negation only. >> >> Meh, for me the pte can only be valid or invalid if it is present. So it's >> implicit. And if you have PTE_PRESENT_INVALID you should also have >> PTE_PRESENT_VALID. >> >> We also have pte_mkinvalid(), which is core-mm-defined. In your scheme, surely >> it should be pte_mkpresent_invalid()? >> >> But you're the boss, I'll change this to PTE_PRESENT_INVALID. :-( > > TBH, I don't have a strong opinion but best to avoid the bikeshedding. > I'll leave the decision to you ;). It would match the pmd_mkinvalid() > core code. But if you drop 'present' make sure you add a comment above > that it's meant for present ptes.
FWIW, I was confused by
present = valid | invalid
Something like
present = present_valid | present_invalid
would be more obvious at least to me ;)
-- Cheers,
David / dhildenb
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