Re: [PATCH v3 25/34] m68k: Convert various functions to use ptdescs

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Vishal,

On Wed, May 31, 2023 at 11:32 PM Vishal Moola (Oracle)
<vishal.moola@gmail.com> wrote:
> As part of the conversions to replace pgtable constructor/destructors with
> ptdesc equivalents, convert various page table functions to use ptdescs.
>
> Some of the functions use the *get*page*() helper functions. Convert
> these to use pagetable_alloc() and ptdesc_address() instead to help
> standardize page tables further.
>
> Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>

Thanks for your patch!

> --- a/arch/m68k/include/asm/mcf_pgalloc.h
> +++ b/arch/m68k/include/asm/mcf_pgalloc.h
> @@ -7,20 +7,19 @@
>
>  extern inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
>  {
> -       free_page((unsigned long) pte);
> +       pagetable_free(virt_to_ptdesc(pte));
>  }
>
>  extern const char bad_pmd_string[];
>
>  extern inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
>  {
> -       unsigned long page = __get_free_page(GFP_DMA);
> +       struct ptdesc *ptdesc = pagetable_alloc(GFP_DMA | __GFP_ZERO, 0);
>
> -       if (!page)
> +       if (!ptdesc)
>                 return NULL;
>
> -       memset((void *)page, 0, PAGE_SIZE);
> -       return (pte_t *) (page);
> +       return (pte_t *) (ptdesc_address(ptdesc));

No need to cast "void *" when returning a different pointer type.

>  }
>
>  extern inline pmd_t *pmd_alloc_kernel(pgd_t *pgd, unsigned long address)
> @@ -35,36 +34,36 @@ extern inline pmd_t *pmd_alloc_kernel(pgd_t *pgd, unsigned long address)
>  static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pgtable,
>                                   unsigned long address)
>  {
> -       struct page *page = virt_to_page(pgtable);
> +       struct ptdesc *ptdesc = virt_to_ptdesc(pgtable);
>
> -       pgtable_pte_page_dtor(page);
> -       __free_page(page);
> +       pagetable_pte_dtor(ptdesc);
> +       pagetable_free(ptdesc);
>  }
>
>  static inline pgtable_t pte_alloc_one(struct mm_struct *mm)
>  {
> -       struct page *page = alloc_pages(GFP_DMA, 0);
> +       struct ptdesc *ptdesc = pagetable_alloc(GFP_DMA, 0);
>         pte_t *pte;
>
> -       if (!page)
> +       if (!ptdesc)
>                 return NULL;
> -       if (!pgtable_pte_page_ctor(page)) {
> -               __free_page(page);
> +       if (!pagetable_pte_ctor(ptdesc)) {
> +               pagetable_free(ptdesc);
>                 return NULL;
>         }
>
> -       pte = page_address(page);
> -       clear_page(pte);
> +       pte = ptdesc_address(ptdesc);
> +       pagetable_clear(pte);
>
>         return pte;
>  }
>
>  static inline void pte_free(struct mm_struct *mm, pgtable_t pgtable)
>  {
> -       struct page *page = virt_to_page(pgtable);
> +       struct ptdesc *ptdesc = virt_to_ptdesc(ptdesc);

virt_to_ptdesc(pgtable)

(You can build this using m5475evb_defconfig)

>
> -       pgtable_pte_page_dtor(page);
> -       __free_page(page);
> +       pagetable_pte_dtor(ptdesc);
> +       pagetable_free(ptdesc);
>  }
>
>  /*
> @@ -75,16 +74,18 @@ static inline void pte_free(struct mm_struct *mm, pgtable_t pgtable)
>
>  static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
>  {
> -       free_page((unsigned long) pgd);
> +       pagetable_free(virt_to_ptdesc(pgd));
>  }
>
>  static inline pgd_t *pgd_alloc(struct mm_struct *mm)
>  {
>         pgd_t *new_pgd;
> +       struct ptdesc *ptdesc = pagetable_alloc(GFP_DMA | GFP_NOWARN, 0);
>
> -       new_pgd = (pgd_t *)__get_free_page(GFP_DMA | __GFP_NOWARN);
> -       if (!new_pgd)
> +       if (!ptdesc)
>                 return NULL;
> +       new_pgd = (pgd_t *) ptdesc_address(ptdesc);

No need to cast "void *" when assigning to a different pointer type.

> +
>         memcpy(new_pgd, swapper_pg_dir, PTRS_PER_PGD * sizeof(pgd_t));
>         memset(new_pgd, 0, PAGE_OFFSET >> PGDIR_SHIFT);
>         return new_pgd;

The rest LGTM.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds