Re: [PATCH 1/2] mm: pgtable: Make generic pgprot_* macros available for no-MMU

[Mike Rapoport <rppt@linux.ibm.com>]

On Tue, Jul 14, 2020 at 01:00:50PM +0300, Pekka Enberg wrote:
> From: Pekka Enberg <penberg@kernel.org>
> 
> The <linux/pgtable.h> header defines some generic pgprot_*
> implementations, but they are only available when CONFIG_MMU is enabled.
> The RISC-V architecture, for example, therefore defines some of these
> pgprot_* macros for !NOMMU.
> 
> Let's make the pgprot_* generic available even for !NOMMU so we can
> remove the RISC-V specific definitions.
> 
> Compile-tested with x86 defconfig, and riscv defconfig and !MMU defconfig.
> 
> Suggested-by: Palmer Dabbelt <palmerdabbelt@google.com>
> Cc: Mike Rapoport <rppt@linux.ibm.com>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Signed-off-by: Pekka Enberg <penberg@kernel.org>

Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>

> ---
>  include/linux/pgtable.h | 69 +++++++++++++++++++++--------------------
>  1 file changed, 35 insertions(+), 34 deletions(-)
> 
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index 56c1e8eb7bb0..ed9026ad7c31 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -647,40 +647,6 @@ static inline int arch_unmap_one(struct mm_struct *mm,
>  #define flush_tlb_fix_spurious_fault(vma, address) flush_tlb_page(vma, address)
>  #endif
>  
> -#ifndef pgprot_nx
> -#define pgprot_nx(prot)	(prot)
> -#endif
> -
> -#ifndef pgprot_noncached
> -#define pgprot_noncached(prot)	(prot)
> -#endif
> -
> -#ifndef pgprot_writecombine
> -#define pgprot_writecombine pgprot_noncached
> -#endif
> -
> -#ifndef pgprot_writethrough
> -#define pgprot_writethrough pgprot_noncached
> -#endif
> -
> -#ifndef pgprot_device
> -#define pgprot_device pgprot_noncached
> -#endif
> -
> -#ifndef pgprot_modify
> -#define pgprot_modify pgprot_modify
> -static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
> -{
> -	if (pgprot_val(oldprot) == pgprot_val(pgprot_noncached(oldprot)))
> -		newprot = pgprot_noncached(newprot);
> -	if (pgprot_val(oldprot) == pgprot_val(pgprot_writecombine(oldprot)))
> -		newprot = pgprot_writecombine(newprot);
> -	if (pgprot_val(oldprot) == pgprot_val(pgprot_device(oldprot)))
> -		newprot = pgprot_device(newprot);
> -	return newprot;
> -}
> -#endif
> -
>  /*
>   * When walking page tables, get the address of the next boundary,
>   * or the end address of the range if that comes earlier.  Although no
> @@ -840,6 +806,41 @@ static inline void ptep_modify_prot_commit(struct vm_area_struct *vma,
>   * No-op macros that just return the current protection value. Defined here
>   * because these macros can be used used even if CONFIG_MMU is not defined.
>   */
> +
> +#ifndef pgprot_nx
> +#define pgprot_nx(prot)	(prot)
> +#endif
> +
> +#ifndef pgprot_noncached
> +#define pgprot_noncached(prot)	(prot)
> +#endif
> +
> +#ifndef pgprot_writecombine
> +#define pgprot_writecombine pgprot_noncached
> +#endif
> +
> +#ifndef pgprot_writethrough
> +#define pgprot_writethrough pgprot_noncached
> +#endif
> +
> +#ifndef pgprot_device
> +#define pgprot_device pgprot_noncached
> +#endif
> +
> +#ifndef pgprot_modify
> +#define pgprot_modify pgprot_modify
> +static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
> +{
> +	if (pgprot_val(oldprot) == pgprot_val(pgprot_noncached(oldprot)))
> +		newprot = pgprot_noncached(newprot);
> +	if (pgprot_val(oldprot) == pgprot_val(pgprot_writecombine(oldprot)))
> +		newprot = pgprot_writecombine(newprot);
> +	if (pgprot_val(oldprot) == pgprot_val(pgprot_device(oldprot)))
> +		newprot = pgprot_device(newprot);
> +	return newprot;
> +}
> +#endif
> +
>  #ifndef pgprot_encrypted
>  #define pgprot_encrypted(prot)	(prot)
>  #endif
> -- 
> 2.26.2
> 

-- 
Sincerely yours,
Mike.

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