linux-kernel - Re: [PATCH V4 02/26] mm/mmap: Define DECLARE_VM_GET_PAGE

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Message-ID: <d3676fce-2dc7-6331-66f5-7009ac45f605@csgroup.eu>
Date:   Fri, 24 Jun 2022 05:28:48 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Anshuman Khandual <anshuman.khandual@....com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>
CC:     "hch@...radead.org" <hch@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
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Subject: Re: [PATCH V4 02/26] mm/mmap: Define DECLARE_VM_GET_PAGE_PROT



Le 24/06/2022 à 06:43, Anshuman Khandual a écrit :
> This just converts the generic vm_get_page_prot() implementation into a new
> macro i.e DECLARE_VM_GET_PAGE_PROT which later can be used across platforms
> when enabling them with ARCH_HAS_VM_GET_PAGE_PROT. This does not create any
> functional change.
> 
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: linux-mm@...ck.org
> Cc: linux-kernel@...r.kernel.org
> Suggested-by: Christoph Hellwig <hch@...radead.org>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> ---
>   include/linux/mm.h | 8 ++++++++
>   mm/mmap.c          | 6 +-----
>   2 files changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 47bfe038d46e..237828c2bae2 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -428,6 +428,14 @@ extern unsigned int kobjsize(const void *objp);
>   extern pgprot_t protection_map[16];
>   #endif
>   

I think the comment above protection_map[16] in mm/mmap.c should be 
moved here.

> +#define DECLARE_VM_GET_PAGE_PROT					\
> +pgprot_t vm_get_page_prot(unsigned long vm_flags)			\
> +{									\
> +		return protection_map[vm_flags &			\
> +			(VM_READ | VM_WRITE | VM_EXEC | VM_SHARED)];	\
> +}									\
> +EXPORT_SYMBOL(vm_get_page_prot);
> +
>   /*
>    * The default fault flags that should be used by most of the
>    * arch-specific page fault handlers.
> diff --git a/mm/mmap.c b/mm/mmap.c
> index b01f0280bda2..55c30aee3999 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -123,11 +123,7 @@ pgprot_t protection_map[16] __ro_after_init = {
>   #endif
>   
>   #ifndef CONFIG_ARCH_HAS_VM_GET_PAGE_PROT
> -pgprot_t vm_get_page_prot(unsigned long vm_flags)
> -{
> -	return protection_map[vm_flags & (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)];
> -}
> -EXPORT_SYMBOL(vm_get_page_prot);
> +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)