Re: [PATCH 16/18] ARC: mm: support 4 levels of page tables

[Vineet Gupta]

On 8/11/21 5:28 AM, Mike Rapoport wrote:
> On Tue, Aug 10, 2021 at 05:42:56PM -0700, Vineet Gupta wrote:
> > Signed-off-by: Vineet Gupta<vgupta@xxxxxxxxxx>
> > ---
> >   arch/arc/include/asm/page.h           | 11 +++++++
> >   arch/arc/include/asm/pgalloc.h        | 22 +++++++++++++
> >   arch/arc/include/asm/pgtable-levels.h | 45 ++++++++++++++++++++++++---
> >   arch/arc/mm/fault.c                   |  2 ++
> >   arch/arc/mm/tlbex.S                   |  9 ++++++
> >   5 files changed, 84 insertions(+), 5 deletions(-)
> >
> > diff --git a/arch/arc/include/asm/page.h b/arch/arc/include/asm/page.h
> > index df3cc154ae4a..883856f12afe 100644
> > --- a/arch/arc/include/asm/page.h
> > +++ b/arch/arc/include/asm/page.h
> > @@ -41,6 +41,17 @@ typedef struct {
> >   #define pgd_val(x)	((x).pgd)
> >   #define __pgd(x)	((pgd_t) { (x) })
> >   
> > +#if CONFIG_PGTABLE_LEVELS > 3
> > +
> > +typedef struct {
> > +	unsigned long pud;
> > +} pud_t;
> > +
> > +#define pud_val(x)      	((x).pud)
> > +#define __pud(x)        	((pud_t) { (x) })
> > +
> > +#endif
> > +
> >   #if CONFIG_PGTABLE_LEVELS > 2
> >   
> >   typedef struct {
> > diff --git a/arch/arc/include/asm/pgalloc.h b/arch/arc/include/asm/pgalloc.h
> > index 01c2d84418ed..e99c724d9235 100644
> > --- a/arch/arc/include/asm/pgalloc.h
> > +++ b/arch/arc/include/asm/pgalloc.h
> > @@ -86,6 +86,28 @@ static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
> >   }
> >   
> >   
> > +#if CONFIG_PGTABLE_LEVELS > 3
> > +
> > +static inline void p4d_populate(struct mm_struct *mm, p4d_t *p4dp, pud_t *pudp)
> > +{
> > +	set_p4d(p4dp, __p4d((unsigned long)pudp));
> > +}
> > +
> > +static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr)
> > +{
> > +	return (pud_t *)__get_free_page(
> > +		GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_ZERO);
> > +}
> > +
> > +static inline void pud_free(struct mm_struct *mm, pud_t *pudp)
> > +{
> > +	free_page((unsigned long)pudp);
> > +}
> > +
> > +#define __pud_free_tlb(tlb, pmd, addr)  pud_free((tlb)->mm, pmd)
> > +
> > +#endif
> > +
> >   #if CONFIG_PGTABLE_LEVELS > 2
> >   
> >   static inline void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmdp)
> > diff --git a/arch/arc/include/asm/pgtable-levels.h b/arch/arc/include/asm/pgtable-levels.h
> > index 1c2f022d4ad0..2da3c4e52a91 100644
> > --- a/arch/arc/include/asm/pgtable-levels.h
> > +++ b/arch/arc/include/asm/pgtable-levels.h
> > @@ -44,8 +44,13 @@
> >   /*
> >    * A default 3 level paging testing setup in software walked MMU
> >    *   MMUv4 (8K page): <4> : <7> : <8> : <13>
> > + * A default 4 level paging testing setup in software walked MMU
> > + *   MMUv4 (8K page): <4> : <3> : <4> : <8> : <13>
> >    */
> >   #define PGDIR_SHIFT		28
> > +#if CONFIG_PGTABLE_LEVELS > 3
> > +#define PUD_SHIFT		25
> > +#endif
> >   #if CONFIG_PGTABLE_LEVELS > 2
> >   #define PMD_SHIFT		21
> >   #endif
> > @@ -56,17 +61,25 @@
> >   #define PGDIR_MASK		(~(PGDIR_SIZE - 1))
> >   #define PTRS_PER_PGD		BIT(32 - PGDIR_SHIFT)
> >   
> > +#if CONFIG_PGTABLE_LEVELS > 3
> > +#define PUD_SIZE		BIT(PUD_SHIFT)
> > +#define PUD_MASK		(~(PUD_SIZE - 1))
> > +#define PTRS_PER_PUD		BIT(PGDIR_SHIFT - PUD_SHIFT)
> Maybe move these into the previous #if CONFIG_PGTABLE_LEVELS > 3?

Same reasoning as the prev one. Sure there's a bit more ifdef'ery but I 
think it looks more organized to me. But if you really feel strongly I 
can move the code around.

-Vineet