Re: [PATCH V5 6/7] mm/mmap: Drop arch_filter_pgprot()

[Christophe Leroy]

Le 12/04/2022 à 06:38, Anshuman Khandual a écrit :
> There are no platforms left which subscribe ARCH_HAS_FILTER_PGPROT. Hence
> drop generic arch_filter_pgprot() and also config ARCH_HAS_FILTER_PGPROT.
> 
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
> ---
>   mm/Kconfig | 3 ---
>   mm/mmap.c  | 9 +--------
>   2 files changed, 1 insertion(+), 11 deletions(-)
> 
> diff --git a/mm/Kconfig b/mm/Kconfig
> index b1f7624276f8..3f7b6d7b69df 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -762,9 +762,6 @@ config ARCH_HAS_CURRENT_STACK_POINTER
>   	  register alias named "current_stack_pointer", this config can be
>   	  selected.
>   
> -config ARCH_HAS_FILTER_PGPROT
> -	bool
> -
>   config ARCH_HAS_VM_GET_PAGE_PROT
>   	bool
>   
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 87cb2eaf7e1a..edf2a5e38f4d 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -107,20 +107,13 @@ pgprot_t protection_map[16] __ro_after_init = {
>   };
>   
>   #ifndef CONFIG_ARCH_HAS_VM_GET_PAGE_PROT
> -#ifndef CONFIG_ARCH_HAS_FILTER_PGPROT
> -static inline pgprot_t arch_filter_pgprot(pgprot_t prot)
> -{
> -	return prot;
> -}
> -#endif
> -
>   pgprot_t vm_get_page_prot(unsigned long vm_flags)
>   {
>   	pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags &
>   				(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
>   			pgprot_val(arch_vm_get_page_prot(vm_flags)));
>   
> -	return arch_filter_pgprot(ret);
> +	return ret;

You can drop 'ret' and directly do:

	return  __pgprot(pgprot_val(protection_map[vm_flags &
			(VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) |
			pgprot_val(arch_vm_get_page_prot(vm_flags)));


>   }
>   EXPORT_SYMBOL(vm_get_page_prot);
>   #endif	/* CONFIG_ARCH_HAS_VM_GET_PAGE_PROT */