linux-kernel - Re: [PATCH 06/10] arm64: mm: Simplify __TLBI_RANGE

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Message-ID: <663e10b2-5f66-4db1-9e7d-6d7538f5f58a@arm.com>
Date: Mon, 14 Jul 2025 10:06:20 +0100
From: Ryan Roberts <ryan.roberts@....com>
To: Will Deacon <will@...nel.org>, linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>,
 Catalin Marinas <catalin.marinas@....com>,
 Mark Rutland <mark.rutland@....com>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Oliver Upton <oliver.upton@...ux.dev>, Marc Zyngier <maz@...nel.org>
Subject: Re: [PATCH 06/10] arm64: mm: Simplify __TLBI_RANGE_NUM() macro

On 11/07/2025 17:17, Will Deacon wrote:
> Since commit e2768b798a19 ("arm64/mm: Modify range-based tlbi to
> decrement scale"), we don't need to clamp the 'pages' argument to fit
> the range for the specified 'scale' as we know that the upper bits will
> have been processed in a prior iteration.
> 
> Drop the clamping and simplify the __TLBI_RANGE_NUM() macro.
> 
> Signed-off-by: Will Deacon <will@...nel.org>

Seems reasonable:

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

> ---
>  arch/arm64/include/asm/tlbflush.h | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> index ddd77e92b268..a8d21e52ef3a 100644
> --- a/arch/arm64/include/asm/tlbflush.h
> +++ b/arch/arm64/include/asm/tlbflush.h
> @@ -205,11 +205,7 @@ static __always_inline void __tlbi_level(const enum tlbi_op op, u64 addr, u32 le
>   * range.
>   */
>  #define __TLBI_RANGE_NUM(pages, scale)					\
> -	({								\
> -		int __pages = min((pages),				\
> -				  __TLBI_RANGE_PAGES(31, (scale)));	\
> -		(__pages >> (5 * (scale) + 1)) - 1;			\
> -	})
> +	(((pages) >> (5 * (scale) + 1)) - 1)
>  
>  /*
>   *	TLB Invalidation