linux-kernel - Re: [PATCH] arm64/mm: Drop INIT_MM

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Message-ID: <3050a0b3-95f6-48aa-8850-e921bd848f85@arm.com>
Date: Mon, 2 Dec 2024 11:38:34 +0000
From: Ryan Roberts <ryan.roberts@....com>
To: Anshuman Khandual <anshuman.khandual@....com>,
 linux-arm-kernel@...ts.infradead.org
Cc: Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
 Ard Biesheuvel <ardb@...nel.org>, Mark Rutland <mark.rutland@....com>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64/mm: Drop INIT_MM_CONTEXT()

On 02/12/2024 04:35, Anshuman Khandual wrote:
> Platform override for INIT_MM_CONTEXT() is redundant because swapper_pg_dir
> always gets assigned as the pgd during init_mm initialization. So just drop
> this override on arm64.
> 
> Originally this override was added via the 'commit 2b5548b68199 ("arm64/mm:
> Separate boot-time page tables from swapper_pg_dir")' because non standard
> init_pg_dir was assigned as the pgd. Subsequently it was changed as default
> swapper_pg_dir by the 'commit ba5b0333a847 ("arm64: mm: omit redundant
> remap of kernel image")', which might have also just dropped this override.
> 
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will@...nel.org>
> Cc: Ard Biesheuvel <ardb@...nel.org>
> Cc: Ryan Roberts <ryan.roberts@....com>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>

Reviewed-by: Ryan Roberts <ryan.roberts@....com>

> ---
> This patch applies on v6.13-rc1
> 
>  arch/arm64/include/asm/mmu.h | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h
> index 2ec96d91acc6..662471cfc536 100644
> --- a/arch/arm64/include/asm/mmu.h
> +++ b/arch/arm64/include/asm/mmu.h
> @@ -109,8 +109,5 @@ static inline bool kaslr_requires_kpti(void)
>  	return true;
>  }
>  
> -#define INIT_MM_CONTEXT(name)	\
> -	.pgd = swapper_pg_dir,
> -
>  #endif	/* !__ASSEMBLY__ */
>  #endif