[PATCH v4 2/5] arm64: mm: factor out the address and ptep alignment into a new helper

[Ryan Roberts]

On 23/12/2025 05:48, Baolin Wang wrote:
> Factor out the contpte block's address and ptep alignment into a new helper,
> and will be reused in the following patch.
> 
> No functional changes.
> 
> Signed-off-by: Baolin Wang <baolin.wang at linux.alibaba.com>

LGTM:

Reviewed-by: Ryan Roberts <ryan.roberts at arm.com>

> ---
>  arch/arm64/mm/contpte.c | 29 +++++++++++++++++++++--------
>  1 file changed, 21 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm64/mm/contpte.c b/arch/arm64/mm/contpte.c
> index 589bcf878938..e4ddeb46f25d 100644
> --- a/arch/arm64/mm/contpte.c
> +++ b/arch/arm64/mm/contpte.c
> @@ -26,6 +26,26 @@ static inline pte_t *contpte_align_down(pte_t *ptep)
>  	return PTR_ALIGN_DOWN(ptep, sizeof(*ptep) * CONT_PTES);
>  }
>  
> +static inline pte_t *contpte_align_addr_ptep(unsigned long *start,
> +					     unsigned long *end, pte_t *ptep,
> +					     unsigned int nr)
> +{
> +	/*
> +	 * Note: caller must ensure these nr PTEs are consecutive (present)
> +	 * PTEs that map consecutive pages of the same large folio within a
> +	 * single VMA and a single page table.
> +	 */
> +	if (pte_cont(__ptep_get(ptep + nr - 1)))
> +		*end = ALIGN(*end, CONT_PTE_SIZE);
> +
> +	if (pte_cont(__ptep_get(ptep))) {
> +		*start = ALIGN_DOWN(*start, CONT_PTE_SIZE);
> +		ptep = contpte_align_down(ptep);
> +	}
> +
> +	return ptep;
> +}
> +
>  static void contpte_try_unfold_partial(struct mm_struct *mm, unsigned long addr,
>  					pte_t *ptep, unsigned int nr)
>  {
> @@ -569,14 +589,7 @@ void contpte_clear_young_dirty_ptes(struct vm_area_struct *vma,
>  	unsigned long start = addr;
>  	unsigned long end = start + nr * PAGE_SIZE;
>  
> -	if (pte_cont(__ptep_get(ptep + nr - 1)))
> -		end = ALIGN(end, CONT_PTE_SIZE);
> -
> -	if (pte_cont(__ptep_get(ptep))) {
> -		start = ALIGN_DOWN(start, CONT_PTE_SIZE);
> -		ptep = contpte_align_down(ptep);
> -	}
> -
> +	ptep = contpte_align_addr_ptep(&start, &end, ptep, nr);
>  	__clear_young_dirty_ptes(vma, start, ptep, (end - start) / PAGE_SIZE, flags);
>  }
>  EXPORT_SYMBOL_GPL(contpte_clear_young_dirty_ptes);