Re: [PATCH v16 06/25] powerpc: mm: Add p?d_leaf() definitions

Michael Ellerman
2019-12-09T11:08:46Z

Steven Price <steven.price@arm.com> writes:
> walk_page_range() is going to be allowed to walk page tables other than
> those of user space. For this it needs to know when it has reached a
> 'leaf' entry in the page tables. This information is provided by the
> p?d_leaf() functions/macros.
>
> For powerpc pmd_large() already exists and does what we want, so hoist
> it out of the CONFIG_TRANSPARENT_HUGEPAGE condition and implement the
> other levels. Macros are used to provide the generic p?d_leaf() names.
>
> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> CC: Paul Mackerras <paulus@samba.org>
> CC: Michael Ellerman <mpe@ellerman.id.au>
> CC: linuxppc-dev@lists.ozlabs.org
> CC: kvm-ppc@vger.kernel.org
> Signed-off-by: Steven Price <steven.price@arm.com>
> ---
> arch/powerpc/include/asm/book3s/64/pgtable.h | 30 ++++++++++++++------
> 1 file changed, 21 insertions(+), 9 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h
> index b01624e5c467..3dd7b6f5edd0 100644
> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
> @@ -923,6 +923,12 @@ static inline int pud_present(pud_t pud)
> return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PRESENT));
> }
>
> +#define pud_leaf pud_large
> +static inline int pud_large(pud_t pud)
> +{
> + return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
> +}

We already have:

#define pud_is_leaf pud_is_leaf
static inline bool pud_is_leaf(pud_t pud)
{
return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
}

And so on.

These went in relatively recently in:

d6eacedd1f0e ("powerpc/book3s: Use config independent helpers for page table walk")

Assuming those all work for you, maybe your patch in this series should
just do:

#define pud_leaf pud_is_leaf

And so on. And then we can do a patch later to change the arch/powerpc
code to use pud_leaf() etc. directly and drop the "is" versions.

cheers

> @@ -966,6 +972,12 @@ static inline int pgd_present(pgd_t pgd)
> return !!(pgd_raw(pgd) & cpu_to_be64(_PAGE_PRESENT));
> }
>
> +#define pgd_leaf pgd_large
> +static inline int pgd_large(pgd_t pgd)
> +{
> + return !!(pgd_raw(pgd) & cpu_to_be64(_PAGE_PTE));
> +}
> +
> static inline pte_t pgd_pte(pgd_t pgd)
> {
> return __pte_raw(pgd_raw(pgd));
> @@ -1133,6 +1145,15 @@ static inline bool pmd_access_permitted(pmd_t pmd, bool write)
> return pte_access_permitted(pmd_pte(pmd), write);
> }
>
> +#define pmd_leaf pmd_large
> +/*
> + * returns true for pmd migration entries, THP, devmap, hugetlb
> + */
> +static inline int pmd_large(pmd_t pmd)
> +{
> + return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
> +}
> +
> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
> extern pmd_t pfn_pmd(unsigned long pfn, pgprot_t pgprot);
> extern pmd_t mk_pmd(struct page *page, pgprot_t pgprot);
> @@ -1159,15 +1180,6 @@ pmd_hugepage_update(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp,
> return hash__pmd_hugepage_update(mm, addr, pmdp, clr, set);
> }
>
> -/*
> - * returns true for pmd migration entries, THP, devmap, hugetlb
> - * But compile time dependent on THP config
> - */
> -static inline int pmd_large(pmd_t pmd)
> -{
> - return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
> -}
> -
> static inline pmd_t pmd_mknotpresent(pmd_t pmd)
> {
> return __pmd(pmd_val(pmd) & ~_PAGE_PRESENT);
> --
> 2.20.1