Re: [PATCH v2 7/8] powerpc/pgtable: remove _PAGE_BIT_SWAP_TYPE for book3s

Christophe Leroy
2022-03-30T06:07:30Z

Le 29/03/2022 à 18:43, David Hildenbrand a écrit :
> The swap type is simply stored in bits 0x1f of the swap pte. Let's
> simplify by just getting rid of _PAGE_BIT_SWAP_TYPE. It's not like that
> we can simply change it: _PAGE_SWP_SOFT_DIRTY would suddenly fall into
> _RPAGE_RSV1, which isn't possible and would make the
> BUILD_BUG_ON(_PAGE_HPTEFLAGS & _PAGE_SWP_SOFT_DIRTY) angry.
>
> While at it, make it clearer which bit we're actually using for
> _PAGE_SWP_SOFT_DIRTY by just using the proper define and introduce and
> use SWP_TYPE_MASK.
>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
> arch/powerpc/include/asm/book3s/64/pgtable.h | 12 +++++-------

Why only BOOK3S ? Why not BOOK3E as well ?

Christophe

> 1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index 875730d5af40..8e98375d5c4a 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -13,7 +13,6 @@
> /*
> * Common bits between hash and Radix page table
> */
> -#define _PAGE_BIT_SWAP_TYPE 0
>
> #define _PAGE_EXEC 0x00001 /* execute permission */
> #define _PAGE_WRITE 0x00002 /* write access allowed */
> @@ -751,17 +750,16 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
> * Don't have overlapping bits with _PAGE_HPTEFLAGS \
> * We filter HPTEFLAGS on set_pte. \
> */ \
> - BUILD_BUG_ON(_PAGE_HPTEFLAGS & (0x1f << _PAGE_BIT_SWAP_TYPE)); \
> + BUILD_BUG_ON(_PAGE_HPTEFLAGS & SWP_TYPE_MASK); \
> BUILD_BUG_ON(_PAGE_HPTEFLAGS & _PAGE_SWP_SOFT_DIRTY); \
> } while (0)
>
> #define SWP_TYPE_BITS 5
> -#define __swp_type(x) (((x).val >> _PAGE_BIT_SWAP_TYPE) \
> - & ((1UL << SWP_TYPE_BITS) - 1))
> +#define SWP_TYPE_MASK ((1UL << SWP_TYPE_BITS) - 1)
> +#define __swp_type(x) ((x).val & SWP_TYPE_MASK)
> #define __swp_offset(x) (((x).val & PTE_RPN_MASK) >> PAGE_SHIFT)
> #define __swp_entry(type, offset) ((swp_entry_t) { \
> - ((type) << _PAGE_BIT_SWAP_TYPE) \
> - | (((offset) << PAGE_SHIFT) & PTE_RPN_MASK)})
> + (type) | (((offset) << PAGE_SHIFT) & PTE_RPN_MASK)})
> /*
> * swp_entry_t must be independent of pte bits. We build a swp_entry_t from
> * swap type and offset we get from swap and convert that to pte to find a
> @@ -774,7 +772,7 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
> #define __swp_entry_to_pmd(x) (pte_pmd(__swp_entry_to_pte(x)))
>
> #ifdef CONFIG_MEM_SOFT_DIRTY
> -#define _PAGE_SWP_SOFT_DIRTY (1UL << (SWP_TYPE_BITS + _PAGE_BIT_SWAP_TYPE))
> +#define _PAGE_SWP_SOFT_DIRTY _PAGE_NON_IDEMPOTENT
> #else
> #define _PAGE_SWP_SOFT_DIRTY 0UL
> #endif /* CONFIG_MEM_SOFT_DIRTY */