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Date:   Mon, 11 Jul 2022 15:43:45 -0500
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Subject: Re: [PATCH V7 15/26] nios2/mm: Enable ARCH_HAS_VM_GET_PAGE_PROT
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To:     Anshuman Khandual <anshuman.khandual@arm.com>, linux-mm@kvack.org,
        akpm@linux-foundation.org
Cc:     hch@infradead.org, christophe.leroy@csgroup.eu,
        linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org,
        x86@kernel.org, openrisc@lists.librecores.org,
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        linux-alpha@vger.kernel.org, linux-riscv@lists.infradead.org,
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References: <20220711070600.2378316-1-anshuman.khandual@arm.com>
 <20220711070600.2378316-16-anshuman.khandual@arm.com>
From:   Dinh Nguyen <dinguyen@kernel.org>
In-Reply-To: <20220711070600.2378316-16-anshuman.khandual@arm.com>
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On 7/11/22 02:05, Anshuman Khandual wrote:
> 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.
> 
> 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             | 20 ++++++++++++++++++++
>   3 files changed, 21 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/nios2/Kconfig b/arch/nios2/Kconfig
> index 4167f1eb4cd8..e0459dffd218 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 262d0609268c..470516d4555e 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..ae24687d12ad 100644
> --- a/arch/nios2/mm/init.c
> +++ b/arch/nios2/mm/init.c
> @@ -124,3 +124,23 @@ const char *arch_vma_name(struct vm_area_struct *vma)
>   {
>   	return (vma->vm_start == KUSER_BASE) ? "[kuser]" : NULL;
>   }
> +
> +static const pgprot_t protection_map[16] = {
> +	[VM_NONE]					= MKP(0, 0, 0),
> +	[VM_READ]					= MKP(0, 0, 1),
> +	[VM_WRITE]					= MKP(0, 0, 0),
> +	[VM_WRITE | VM_READ]				= MKP(0, 0, 1),
> +	[VM_EXEC]					= MKP(1, 0, 0),
> +	[VM_EXEC | VM_READ]				= MKP(1, 0, 1),
> +	[VM_EXEC | VM_WRITE]				= MKP(1, 0, 0),
> +	[VM_EXEC | VM_WRITE | VM_READ]			= MKP(1, 0, 1),
> +	[VM_SHARED]					= MKP(0, 0, 0),
> +	[VM_SHARED | VM_READ]				= MKP(0, 0, 1),
> +	[VM_SHARED | VM_WRITE]				= MKP(0, 1, 0),
> +	[VM_SHARED | VM_WRITE | VM_READ]		= MKP(0, 1, 1),
> +	[VM_SHARED | VM_EXEC]				= MKP(1, 0, 0),
> +	[VM_SHARED | VM_EXEC | VM_READ]			= MKP(1, 0, 1),
> +	[VM_SHARED | VM_EXEC | VM_WRITE]		= MKP(1, 1, 0),
> +	[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]	= MKP(1, 1, 1)
> +};
> +DECLARE_VM_GET_PAGE_PROT

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