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

[Vishal Moola <vishal.moola@gmail.com>]

On Thu, Jun 1, 2023 at 12:40 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> 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.

Thanks so much for the review! I'll make those changes in the next
version.


> 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