Re: [PATCH V4 26/26] mm/mmap: Drop ARCH_HAS_VM_GET_PAGE_PROT

[Christophe Leroy <christophe.leroy@csgroup.eu>]

Le 24/06/2022 à 06:43, Anshuman Khandual a écrit :
> Now all the platforms enable ARCH_HAS_GET_PAGE_PROT. They define and export
> own vm_get_page_prot() whether custom or standard DECLARE_VM_GET_PAGE_PROT.
> Hence there is no need for default generic fallback for vm_get_page_prot().
> Just drop this fallback and also ARCH_HAS_GET_PAGE_PROT mechanism.
> 
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
>   arch/alpha/Kconfig      |  1 -
>   arch/arc/Kconfig        |  1 -
>   arch/arm/Kconfig        |  1 -
>   arch/arm64/Kconfig      |  1 -
>   arch/csky/Kconfig       |  1 -
>   arch/hexagon/Kconfig    |  1 -
>   arch/ia64/Kconfig       |  1 -
>   arch/loongarch/Kconfig  |  1 -
>   arch/m68k/Kconfig       |  1 -
>   arch/microblaze/Kconfig |  1 -
>   arch/mips/Kconfig       |  1 -
>   arch/nios2/Kconfig      |  1 -
>   arch/openrisc/Kconfig   |  1 -
>   arch/parisc/Kconfig     |  1 -
>   arch/powerpc/Kconfig    |  1 -
>   arch/riscv/Kconfig      |  1 -
>   arch/s390/Kconfig       |  1 -
>   arch/sh/Kconfig         |  1 -
>   arch/sparc/Kconfig      |  1 -
>   arch/um/Kconfig         |  1 -
>   arch/x86/Kconfig        |  1 -
>   arch/xtensa/Kconfig     |  1 -
>   include/linux/mm.h      |  3 ---
>   mm/Kconfig              |  3 ---
>   mm/mmap.c               | 22 ----------------------
>   25 files changed, 50 deletions(-)
> 
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 43db3bd49071..3557fe83d124 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -101,28 +101,6 @@ static void unmap_region(struct mm_struct *mm,
>    *								w: (no) no
>    *								x: (yes) yes
>    */

The above comment is not orphaned. I think it should go in linux/mm.h

> -#ifndef CONFIG_ARCH_HAS_VM_GET_PAGE_PROT
> -pgprot_t protection_map[16] __ro_after_init = {
> -	[VM_NONE]					= __P000,
> -	[VM_READ]					= __P001,
> -	[VM_WRITE]					= __P010,
> -	[VM_WRITE | VM_READ]				= __P011,
> -	[VM_EXEC]					= __P100,
> -	[VM_EXEC | VM_READ]				= __P101,
> -	[VM_EXEC | VM_WRITE]				= __P110,
> -	[VM_EXEC | VM_WRITE | VM_READ]			= __P111,
> -	[VM_SHARED]					= __S000,
> -	[VM_SHARED | VM_READ]				= __S001,
> -	[VM_SHARED | VM_WRITE]				= __S010,
> -	[VM_SHARED | VM_WRITE | VM_READ]		= __S011,
> -	[VM_SHARED | VM_EXEC]				= __S100,
> -	[VM_SHARED | VM_EXEC | VM_READ]			= __S101,
> -	[VM_SHARED | VM_EXEC | VM_WRITE]		= __S110,
> -	[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]	= __S111
> -};
> -DECLARE_VM_GET_PAGE_PROT
> -#endif	/* CONFIG_ARCH_HAS_VM_GET_PAGE_PROT */
> -
>   static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
>   {
>   	return pgprot_modify(oldprot, vm_get_page_prot(vm_flags));