Re: [RFC V1 25/31] nios2/mm: Enable ARCH_HAS_VM_GET_PAGE_PROT

[Dinh Nguyen <dinguyen@kernel.org>]

On 1/24/22 06:57, Anshuman Khandual wrote:
> This defines and exports a platform specific custom vm_get_page_prot() via
> subscribing ARCH_HAS_VM_GET_PAGE_PROT. Subsequently all __SXXX and __PXXX
> macros can be dropped which are no longer needed.
> 
> Cc: Dinh Nguyen <dinguyen@kernel.org>
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
>   arch/nios2/Kconfig               |  1 +
>   arch/nios2/include/asm/pgtable.h | 16 -------------
>   arch/nios2/mm/init.c             | 41 ++++++++++++++++++++++++++++++++
>   3 files changed, 42 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/nios2/Kconfig b/arch/nios2/Kconfig
> index 33fd06f5fa41..85a58a357a3b 100644
> --- a/arch/nios2/Kconfig
> +++ b/arch/nios2/Kconfig
> @@ -6,6 +6,7 @@ config NIOS2
>   	select ARCH_HAS_SYNC_DMA_FOR_CPU
>   	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
>   	select ARCH_HAS_DMA_SET_UNCACHED
> +	select ARCH_HAS_VM_GET_PAGE_PROT
>   	select ARCH_NO_SWAP
>   	select COMMON_CLK
>   	select TIMER_OF
> diff --git a/arch/nios2/include/asm/pgtable.h b/arch/nios2/include/asm/pgtable.h
> index 4a995fa628ee..2678dad58a63 100644
> --- a/arch/nios2/include/asm/pgtable.h
> +++ b/arch/nios2/include/asm/pgtable.h
> @@ -40,24 +40,8 @@ struct mm_struct;
>    */
>   
>   /* Remove W bit on private pages for COW support */
> -#define __P000	MKP(0, 0, 0)
> -#define __P001	MKP(0, 0, 1)
> -#define __P010	MKP(0, 0, 0)	/* COW */
> -#define __P011	MKP(0, 0, 1)	/* COW */
> -#define __P100	MKP(1, 0, 0)
> -#define __P101	MKP(1, 0, 1)
> -#define __P110	MKP(1, 0, 0)	/* COW */
> -#define __P111	MKP(1, 0, 1)	/* COW */
>   
>   /* Shared pages can have exact HW mapping */
> -#define __S000	MKP(0, 0, 0)
> -#define __S001	MKP(0, 0, 1)
> -#define __S010	MKP(0, 1, 0)
> -#define __S011	MKP(0, 1, 1)
> -#define __S100	MKP(1, 0, 0)
> -#define __S101	MKP(1, 0, 1)
> -#define __S110	MKP(1, 1, 0)
> -#define __S111	MKP(1, 1, 1)
>   
>   /* Used all over the kernel */
>   #define PAGE_KERNEL __pgprot(_PAGE_PRESENT | _PAGE_CACHED | _PAGE_READ | \
> diff --git a/arch/nios2/mm/init.c b/arch/nios2/mm/init.c
> index 613fcaa5988a..4f8251e62f31 100644
> --- a/arch/nios2/mm/init.c
> +++ b/arch/nios2/mm/init.c
> @@ -124,3 +124,44 @@ const char *arch_vma_name(struct vm_area_struct *vma)
>   {
>   	return (vma->vm_start == KUSER_BASE) ? "[kuser]" : NULL;
>   }
> +
> +pgprot_t vm_get_page_prot(unsigned long vm_flags)
> +{
> +	switch (vm_flags & (VM_READ | VM_WRITE | VM_EXEC | VM_SHARED)) {
> +	case VM_NONE:
> +		return MKP(0, 0, 0);
> +	case VM_READ:
> +		return MKP(0, 0, 1);
> +	case VM_WRITE:
> +		return MKP(0, 0, 0);
> +	case VM_READ | VM_WRITE:
> +		return MKP(0, 0, 1);
> +	case VM_EXEC:
> +		return MKP(1, 0, 0);
> +	case VM_EXEC | VM_READ:
> +		return MKP(1, 0, 1);
> +	case VM_EXEC | VM_WRITE:
> +		return MKP(1, 0, 0);
> +	case VM_EXEC | VM_READ | VM_WRITE:
> +		return MKP(1, 0, 1);
> +	case VM_SHARED:
> +		return MKP(0, 0, 0);
> +	case VM_SHARED | VM_READ:
> +		return MKP(0, 0, 1);
> +	case VM_SHARED | VM_WRITE:
> +		return MKP(0, 1, 0);
> +	case VM_SHARED | VM_READ | VM_WRITE:
> +		return MKP(0, 1, 1);
> +	case VM_SHARED | VM_EXEC:
> +		return MKP(1, 0, 0);
> +	case VM_SHARED | VM_EXEC | VM_READ:
> +		return MKP(1, 0, 1);
> +	case VM_SHARED | VM_EXEC | VM_WRITE:
> +		return MKP(1, 1, 0);
> +	case VM_SHARED | VM_EXEC | VM_READ | VM_WRITE:
> +		return MKP(1, 1, 1);
> +	default:
> +		BUILD_BUG();
> +	}
> +}
> +EXPORT_SYMBOL(vm_get_page_prot);


Acked-by: Dinh Nguyen <dinguyen@kernel.org>