linux-kernel - Re: [PATCH v3 2/3] arm64: tlb: Improve __TLBI_VADDR

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Date: Mon, 8 Apr 2024 09:31:36 +0100
From: Ryan Roberts <ryan.roberts@....com>
To: Gavin Shan <gshan@...hat.com>, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Cc: catalin.marinas@....com, will@...nel.org, akpm@...ux-foundation.org,
 maz@...nel.org, oliver.upton@...ux.dev, apopple@...dia.com,
 rananta@...gle.com, mark.rutland@....com, v-songbaohua@...o.com,
 yangyicong@...ilicon.com, shahuang@...hat.com, yihyu@...hat.com,
 shan.gavin@...il.com
Subject: Re: [PATCH v3 2/3] arm64: tlb: Improve __TLBI_VADDR_RANGE()

On 05/04/2024 04:58, Gavin Shan wrote:
> The macro returns the operand of TLBI RANGE instruction. A mask needs
> to be applied to each individual field upon producing the operand, to
> avoid the adjacent fields can interfere with each other when invalid
> arguments have been provided. The code looks more tidy at least with
> a mask and FIELD_PREP().
> 
> Suggested-by: Marc Zyngier <maz@...nel.org>
> Signed-off-by: Gavin Shan <gshan@...hat.com>

LGTM!

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

> ---
>  arch/arm64/include/asm/tlbflush.h | 29 ++++++++++++++++++-----------
>  1 file changed, 18 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> index a75de2665d84..243d71f7bc1f 100644
> --- a/arch/arm64/include/asm/tlbflush.h
> +++ b/arch/arm64/include/asm/tlbflush.h
> @@ -142,17 +142,24 @@ static inline unsigned long get_trans_granule(void)
>   * EL1, Inner Shareable".
>   *
>   */
> -#define __TLBI_VADDR_RANGE(baddr, asid, scale, num, ttl)			\
> -	({									\
> -		unsigned long __ta = (baddr);					\
> -		unsigned long __ttl = (ttl >= 1 && ttl <= 3) ? ttl : 0;		\
> -		__ta &= GENMASK_ULL(36, 0);					\
> -		__ta |= __ttl << 37;						\
> -		__ta |= (unsigned long)(num) << 39;				\
> -		__ta |= (unsigned long)(scale) << 44;				\
> -		__ta |= get_trans_granule() << 46;				\
> -		__ta |= (unsigned long)(asid) << 48;				\
> -		__ta;								\
> +#define TLBIR_ASID_MASK		GENMASK_ULL(63, 48)
> +#define TLBIR_TG_MASK		GENMASK_ULL(47, 46)
> +#define TLBIR_SCALE_MASK	GENMASK_ULL(45, 44)
> +#define TLBIR_NUM_MASK		GENMASK_ULL(43, 39)
> +#define TLBIR_TTL_MASK		GENMASK_ULL(38, 37)
> +#define TLBIR_BADDR_MASK	GENMASK_ULL(36,  0)
> +
> +#define __TLBI_VADDR_RANGE(baddr, asid, scale, num, ttl)		\
> +	({								\
> +		unsigned long __ta = 0;					\
> +		unsigned long __ttl = (ttl >= 1 && ttl <= 3) ? ttl : 0;	\
> +		__ta |= FIELD_PREP(TLBIR_BADDR_MASK, baddr);		\
> +		__ta |= FIELD_PREP(TLBIR_TTL_MASK, __ttl);		\
> +		__ta |= FIELD_PREP(TLBIR_NUM_MASK, num);		\
> +		__ta |= FIELD_PREP(TLBIR_SCALE_MASK, scale);		\
> +		__ta |= FIELD_PREP(TLBIR_TG_MASK, get_trans_granule());	\
> +		__ta |= FIELD_PREP(TLBIR_ASID_MASK, asid);		\
> +		__ta;							\
>  	})
>  
>  /* These macros are used by the TLBI RANGE feature. */