Re: [PATCH V4 08/26] microblaze/mm: Enable ARCH_HAS_VM_GET_PAGE_PROT

[Christophe Leroy]

Le 24/06/2022 à 06:43, Anshuman Khandual a écrit :
> This enables ARCH_HAS_VM_GET_PAGE_PROT on the platform and exports standard
> vm_get_page_prot() implementation via DECLARE_VM_GET_PAGE_PROT, which looks
> up a private and static protection_map[] array. Subsequently all __SXXX and
> __PXXX macros can be dropped which are no longer needed.

In this patch and all following ones, can't protection_map[] be const 
instead of __ro_after_init ?

> 
> Cc: Michal Simek <monstr@xxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
> ---
>   arch/microblaze/Kconfig               |  1 +
>   arch/microblaze/include/asm/pgtable.h | 17 -----------------
>   arch/microblaze/mm/init.c             | 20 ++++++++++++++++++++
>   3 files changed, 21 insertions(+), 17 deletions(-)
> 
> diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
> index 8cf429ad1c84..15f91ba8a0c4 100644
> --- a/arch/microblaze/Kconfig
> +++ b/arch/microblaze/Kconfig
> @@ -7,6 +7,7 @@ config MICROBLAZE
>   	select ARCH_HAS_GCOV_PROFILE_ALL
>   	select ARCH_HAS_SYNC_DMA_FOR_CPU
>   	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
> +	select ARCH_HAS_VM_GET_PAGE_PROT
>   	select ARCH_MIGHT_HAVE_PC_PARPORT
>   	select ARCH_WANT_IPC_PARSE_VERSION
>   	select BUILDTIME_TABLE_SORT
> diff --git a/arch/microblaze/include/asm/pgtable.h b/arch/microblaze/include/asm/pgtable.h
> index 0c72646370e1..ba348e997dbb 100644
> --- a/arch/microblaze/include/asm/pgtable.h
> +++ b/arch/microblaze/include/asm/pgtable.h
> @@ -204,23 +204,6 @@ extern pte_t *va_to_pte(unsigned long address);
>    * We consider execute permission the same as read.
>    * Also, write permissions imply read permissions.
>    */
> -#define __P000	PAGE_NONE
> -#define __P001	PAGE_READONLY_X
> -#define __P010	PAGE_COPY
> -#define __P011	PAGE_COPY_X
> -#define __P100	PAGE_READONLY
> -#define __P101	PAGE_READONLY_X
> -#define __P110	PAGE_COPY
> -#define __P111	PAGE_COPY_X
> -
> -#define __S000	PAGE_NONE
> -#define __S001	PAGE_READONLY_X
> -#define __S010	PAGE_SHARED
> -#define __S011	PAGE_SHARED_X
> -#define __S100	PAGE_READONLY
> -#define __S101	PAGE_READONLY_X
> -#define __S110	PAGE_SHARED
> -#define __S111	PAGE_SHARED_X
>   
>   #ifndef __ASSEMBLY__
>   /*
> diff --git a/arch/microblaze/mm/init.c b/arch/microblaze/mm/init.c
> index f4e503461d24..315fd5024f00 100644
> --- a/arch/microblaze/mm/init.c
> +++ b/arch/microblaze/mm/init.c
> @@ -285,3 +285,23 @@ void * __ref zalloc_maybe_bootmem(size_t size, gfp_t mask)
>   
>   	return p;
>   }
> +
> +static pgprot_t protection_map[16] __ro_after_init = {
> +	[VM_NONE]					= PAGE_NONE,
> +	[VM_READ]					= PAGE_READONLY_X,
> +	[VM_WRITE]					= PAGE_COPY,
> +	[VM_WRITE | VM_READ]				= PAGE_COPY_X,
> +	[VM_EXEC]					= PAGE_READONLY,
> +	[VM_EXEC | VM_READ]				= PAGE_READONLY_X,
> +	[VM_EXEC | VM_WRITE]				= PAGE_COPY,
> +	[VM_EXEC | VM_WRITE | VM_READ]			= PAGE_COPY_X,
> +	[VM_SHARED]					= PAGE_NONE,
> +	[VM_SHARED | VM_READ]				= PAGE_READONLY_X,
> +	[VM_SHARED | VM_WRITE]				= PAGE_SHARED,
> +	[VM_SHARED | VM_WRITE | VM_READ]		= PAGE_SHARED_X,
> +	[VM_SHARED | VM_EXEC]				= PAGE_READONLY,
> +	[VM_SHARED | VM_EXEC | VM_READ]			= PAGE_READONLY_X,
> +	[VM_SHARED | VM_EXEC | VM_WRITE]		= PAGE_SHARED,
> +	[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]	= PAGE_SHARED_X
> +};
> +DECLARE_VM_GET_PAGE_PROT