Re: [PATCH 05/15] csky: switch to generic version of pte allocation

[Guo Ren <guoren@kernel.org>]

Hi Mike,

Acked-by: Guo Ren <ren_guo@c-sky.com>

On Thu, May 02, 2019 at 06:28:32PM +0300, Mike Rapoport wrote:
> The csky implementation pte_alloc_one(), pte_free_kernel() and pte_free()
> is identical to the generic except of lack of __GFP_ACCOUNT for the user
> PTEs allocation.
> 
> Switch csky to use generic version of these functions.
Ok.

> 
> The csky implementation of pte_alloc_one_kernel() is not replaced because
> it does not clear the allocated page but rather sets each PTE in it to a
> non-zero value.
Yes, we must set each PTE to _PAGE_GLOBAL because hardware refill the
MMU TLB entry with two PTEs and it use the result of pte0.global | pte1.global.
If pte0 is valid and pte1 is invalid, we must set _PAGE_GLOBAL in
invalid pte entry. Fortunately, there is no performance issue.

> 
> The pte_free_kernel() and pte_free() versions on csky are identical to the
> generic ones and can be simply dropped.
Ok.

Best Regards
 Guo Ren

> 
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> ---
>  arch/csky/include/asm/pgalloc.h | 30 +++---------------------------
>  1 file changed, 3 insertions(+), 27 deletions(-)
> 
> diff --git a/arch/csky/include/asm/pgalloc.h b/arch/csky/include/asm/pgalloc.h
> index d213bb4..98c571670 100644
> --- a/arch/csky/include/asm/pgalloc.h
> +++ b/arch/csky/include/asm/pgalloc.h
> @@ -8,6 +8,9 @@
>  #include <linux/mm.h>
>  #include <linux/sched.h>
>  
> +#define __HAVE_ARCH_PTE_ALLOC_ONE_KERNEL
> +#include <asm-generic/pgalloc.h>	/* for pte_{alloc,free}_one */
> +
>  static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
>  					pte_t *pte)
>  {
> @@ -39,33 +42,6 @@ static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
>  	return pte;
>  }
>  
> -static inline struct page *pte_alloc_one(struct mm_struct *mm)
> -{
> -	struct page *pte;
> -
> -	pte = alloc_pages(GFP_KERNEL | __GFP_ZERO, 0);
> -	if (!pte)
> -		return NULL;
> -
> -	if (!pgtable_page_ctor(pte)) {
> -		__free_page(pte);
> -		return NULL;
> -	}
> -
> -	return pte;
> -}
> -
> -static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
> -{
> -	free_pages((unsigned long)pte, PTE_ORDER);
> -}
> -
> -static inline void pte_free(struct mm_struct *mm, pgtable_t pte)
> -{
> -	pgtable_page_dtor(pte);
> -	__free_pages(pte, PTE_ORDER);
> -}
> -
>  static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
>  {
>  	free_pages((unsigned long)pgd, PGD_ORDER);
> -- 
> 2.7.4
>