[PATCH] powerpc/8xx: use pmd_off() to access a PMD entry in pte_update()

[PATCH] powerpc/8xx: use pmd_off() to access a PMD entry in pte_update()

[Mike Rapoport]

From: Mike Rapoport <rppt@linux.ibm.com>

The pte_update() implementation for PPC_8xx unfolds page table from the PGD
level to access a PMD entry. Since 8xx has only 2-level page table this can
be simplified with pmd_off() shortcut.

Replace explicit unfolding with pmd_off() and drop defines of pgd_index()
and pgd_offset() that are no longer needed.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---

I think it's powerpc material, but I won't mind if Andrew picks it up :)


 arch/powerpc/include/asm/nohash/32/pgtable.h | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/nohash/32/pgtable.h b/arch/powerpc/include/asm/nohash/32/pgtable.h
index b56f14160ae5..5a590ceaec14 100644
--- a/arch/powerpc/include/asm/nohash/32/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/32/pgtable.h
@@ -205,10 +205,6 @@ static inline void pmd_clear(pmd_t *pmdp)
 	*pmdp = __pmd(0);
 }
 
-/* to find an entry in a page-table-directory */
-#define pgd_index(address)	 ((address) >> PGDIR_SHIFT)
-#define pgd_offset(mm, address)	 ((mm)->pgd + pgd_index(address))
-
 /*
  * PTE updates. This function is called whenever an existing
  * valid PTE is updated. This does -not- include set_pte_at()
@@ -230,6 +226,8 @@ static inline void pmd_clear(pmd_t *pmdp)
  * For other page sizes, we have a single entry in the table.
  */
 #ifdef CONFIG_PPC_8xx
+static pmd_t *pmd_off(struct mm_struct *mm, unsigned long addr);
+
 static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, pte_t *p,
 				     unsigned long clr, unsigned long set, int huge)
 {
@@ -237,7 +235,7 @@ static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, p
 	pte_basic_t old = pte_val(*p);
 	pte_basic_t new = (old & ~(pte_basic_t)clr) | set;
 	int num, i;
-	pmd_t *pmd = pmd_offset(pud_offset(p4d_offset(pgd_offset(mm, addr), addr), addr), addr);
+	pmd_t *pmd = pmd_off(mm, addr);
 
 	if (!huge)
 		num = PAGE_SIZE / SZ_4K;
-- 
2.26.2

Re: [PATCH] powerpc/8xx: use pmd_off() to access a PMD entry in pte_update()

[Christophe Leroy]

Le 15/06/2020 à 11:22, Mike Rapoport a écrit :
> From: Mike Rapoport <rppt@linux.ibm.com>
> 
> The pte_update() implementation for PPC_8xx unfolds page table from the PGD
> level to access a PMD entry. Since 8xx has only 2-level page table this can
> be simplified with pmd_off() shortcut.
> 
> Replace explicit unfolding with pmd_off() and drop defines of pgd_index()
> and pgd_offset() that are no longer needed.
> 
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>

Nice. When I implemented this function, I was not able to use pmd_ptr()
due to some circular header inclusion (See comment in commit log). Looks
like since the replacement of pmd_ptr() by pmd_off(), it works.

Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>

Christophe

> ---
> 
> I think it's powerpc material, but I won't mind if Andrew picks it up :)
> 
> 
>   arch/powerpc/include/asm/nohash/32/pgtable.h | 8 +++-----
>   1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/nohash/32/pgtable.h b/arch/powerpc/include/asm/nohash/32/pgtable.h
> index b56f14160ae5..5a590ceaec14 100644
> --- a/arch/powerpc/include/asm/nohash/32/pgtable.h
> +++ b/arch/powerpc/include/asm/nohash/32/pgtable.h
> @@ -205,10 +205,6 @@ static inline void pmd_clear(pmd_t *pmdp)
>   	*pmdp = __pmd(0);
>   }
>   
> -/* to find an entry in a page-table-directory */
> -#define pgd_index(address)	 ((address) >> PGDIR_SHIFT)
> -#define pgd_offset(mm, address)	 ((mm)->pgd + pgd_index(address))
> -
>   /*
>    * PTE updates. This function is called whenever an existing
>    * valid PTE is updated. This does -not- include set_pte_at()
> @@ -230,6 +226,8 @@ static inline void pmd_clear(pmd_t *pmdp)
>    * For other page sizes, we have a single entry in the table.
>    */
>   #ifdef CONFIG_PPC_8xx
> +static pmd_t *pmd_off(struct mm_struct *mm, unsigned long addr);
> +
>   static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, pte_t *p,
>   				     unsigned long clr, unsigned long set, int huge)
>   {
> @@ -237,7 +235,7 @@ static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, p
>   	pte_basic_t old = pte_val(*p);
>   	pte_basic_t new = (old & ~(pte_basic_t)clr) | set;
>   	int num, i;
> -	pmd_t *pmd = pmd_offset(pud_offset(p4d_offset(pgd_offset(mm, addr), addr), addr), addr);
> +	pmd_t *pmd = pmd_off(mm, addr);
>   
>   	if (!huge)
>   		num = PAGE_SIZE / SZ_4K;
> 

Re: [PATCH] powerpc/8xx: use pmd_off() to access a PMD entry in pte_update()

[Andrew Morton]

On Mon, 15 Jun 2020 12:22:29 +0300 Mike Rapoport <rppt@kernel.org> wrote:

> From: Mike Rapoport <rppt@linux.ibm.com>
> 
> The pte_update() implementation for PPC_8xx unfolds page table from the PGD
> level to access a PMD entry. Since 8xx has only 2-level page table this can
> be simplified with pmd_off() shortcut.
> 
> Replace explicit unfolding with pmd_off() and drop defines of pgd_index()
> and pgd_offset() that are no longer needed.
> 
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> ---
> 
> I think it's powerpc material, but I won't mind if Andrew picks it up :)

Via the powerpc tree would be better, please.

Re: [PATCH] powerpc/8xx: use pmd_off() to access a PMD entry in pte_update()

[Michael Ellerman]

Andrew Morton <akpm@linux-foundation.org> writes:
> On Mon, 15 Jun 2020 12:22:29 +0300 Mike Rapoport <rppt@kernel.org> wrote:
>
>> From: Mike Rapoport <rppt@linux.ibm.com>
>> 
>> The pte_update() implementation for PPC_8xx unfolds page table from the PGD
>> level to access a PMD entry. Since 8xx has only 2-level page table this can
>> be simplified with pmd_off() shortcut.
>> 
>> Replace explicit unfolding with pmd_off() and drop defines of pgd_index()
>> and pgd_offset() that are no longer needed.
>> 
>> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
>> ---
>> 
>> I think it's powerpc material, but I won't mind if Andrew picks it up :)
>
> Via the powerpc tree would be better, please.

I'll take it into next for v5.9, unless there's a reason it needs to go
into v5.8.

cheers

Re: [PATCH] powerpc/8xx: use pmd_off() to access a PMD entry in pte_update()

[Mike Rapoport]

On Wed, Jun 17, 2020 at 09:21:42AM +1000, Michael Ellerman wrote:
> Andrew Morton <akpm@linux-foundation.org> writes:
> > On Mon, 15 Jun 2020 12:22:29 +0300 Mike Rapoport <rppt@kernel.org> wrote:
> >
> >> From: Mike Rapoport <rppt@linux.ibm.com>
> >> 
> >> The pte_update() implementation for PPC_8xx unfolds page table from the PGD
> >> level to access a PMD entry. Since 8xx has only 2-level page table this can
> >> be simplified with pmd_off() shortcut.
> >> 
> >> Replace explicit unfolding with pmd_off() and drop defines of pgd_index()
> >> and pgd_offset() that are no longer needed.
> >> 
> >> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> >> ---
> >> 
> >> I think it's powerpc material, but I won't mind if Andrew picks it up :)
> >
> > Via the powerpc tree would be better, please.
> 
> I'll take it into next for v5.9, unless there's a reason it needs to go
> into v5.8.

I consider it a fixup for 5.8 merge window conflicts. Besides, mering it
now may avoid new conflicts in 5.9 ;-)

> cheers

-- 
Sincerely yours,
Mike.

Re: [PATCH] powerpc/8xx: use pmd_off() to access a PMD entry in pte_update()

[Michael Ellerman]

Mike Rapoport <rppt@kernel.org> writes:
> On Wed, Jun 17, 2020 at 09:21:42AM +1000, Michael Ellerman wrote:
>> Andrew Morton <akpm@linux-foundation.org> writes:
>> > On Mon, 15 Jun 2020 12:22:29 +0300 Mike Rapoport <rppt@kernel.org> wrote:
>> >
>> >> From: Mike Rapoport <rppt@linux.ibm.com>
>> >> 
>> >> The pte_update() implementation for PPC_8xx unfolds page table from the PGD
>> >> level to access a PMD entry. Since 8xx has only 2-level page table this can
>> >> be simplified with pmd_off() shortcut.
>> >> 
>> >> Replace explicit unfolding with pmd_off() and drop defines of pgd_index()
>> >> and pgd_offset() that are no longer needed.
>> >> 
>> >> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
>> >> ---
>> >> 
>> >> I think it's powerpc material, but I won't mind if Andrew picks it up :)
>> >
>> > Via the powerpc tree would be better, please.
>> 
>> I'll take it into next for v5.9, unless there's a reason it needs to go
>> into v5.8.
>
> I consider it a fixup for 5.8 merge window conflicts. Besides, mering it
> now may avoid new conflicts in 5.9 ;-)

OK, I'll pick it up for v5.8.

cheers

Re: [PATCH] powerpc/8xx: use pmd_off() to access a PMD entry in pte_update()

[Michael Ellerman]

On Mon, 15 Jun 2020 12:22:29 +0300, Mike Rapoport wrote:
> The pte_update() implementation for PPC_8xx unfolds page table from the PGD
> level to access a PMD entry. Since 8xx has only 2-level page table this can
> be simplified with pmd_off() shortcut.
> 
> Replace explicit unfolding with pmd_off() and drop defines of pgd_index()
> and pgd_offset() that are no longer needed.

Applied to powerpc/fixes.

[1/1] powerpc/8xx: use pmd_off() to access a PMD entry in pte_update()
      https://git.kernel.org/powerpc/c/687993ccf3b05070598b89fad97410b26d7bc9d2

cheers