Messages in this thread | | | Date | Tue, 30 Apr 2024 14:58:10 +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 14:53, Ryan Roberts wrote: > On 30/04/2024 12:37, David Hildenbrand wrote: >> 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 > > OK fair enough. > >> >> Something like >> >> present = present_valid | present_invalid > > I don't want to change pte_valid() to pte_present_valid(); that would also be a > fair bit of churn.
Yes.
> > I'll take Catalin's suggestion and make this PTE_PRESENT_INVALID and > pte_present_invalid(). And obviously leave pmd_mkinvalid() as it is. > (Conversation in the other thread has concluded that it's ok to invalidate a > non-present pmd afterall).
Works for me.
-- Cheers,
David / dhildenb
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