linux-kernel - Re: [PATCH 01/10] arm64: mm: Introduce a C wrapper for by-level TLB invalidation helpers

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Message-ID: <22879688-eac8-4d76-b406-14a4458e09b0@arm.com>
Date: Mon, 14 Jul 2025 09:38:39 +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 01/10] arm64: mm: Introduce a C wrapper for by-level TLB
 invalidation helpers

On 11/07/2025 17:17, Will Deacon wrote:
> In preparation for reducing our reliance on complex preprocessor macros
> for TLB invalidation routines, introduce a new C wrapper for by-level
> TLB invalidation helpers which can be used instead of the __tlbi() macro
> and can additionally be called from C code.
> 
> Signed-off-by: Will Deacon <will@...nel.org>
> ---
>  arch/arm64/include/asm/tlbflush.h | 33 ++++++++++++++++++++++++++++++-
>  1 file changed, 32 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
> index aa9efee17277..1c7548ec6cb7 100644
> --- a/arch/arm64/include/asm/tlbflush.h
> +++ b/arch/arm64/include/asm/tlbflush.h
> @@ -88,6 +88,16 @@ static inline unsigned long get_trans_granule(void)
>  	}
>  }
>  
> +enum tlbi_op {
> +	vae1is,
> +	vae2is,
> +	vale1is,
> +	vale2is,
> +	vaale1is,
> +	ipas2e1,
> +	ipas2e1is,
> +};
> +
>  /*
>   * Level-based TLBI operations.
>   *
> @@ -105,6 +115,27 @@ static inline unsigned long get_trans_granule(void)
>  
>  #define TLBI_TTL_UNKNOWN	INT_MAX
>  
> +#define __GEN_TLBI_OP_CASE(op)						\

nit: my personal preference would be to explicitly pass arg into the macro
instead of implicitly picking it from the parent context.


> +	case op:							\
> +		__tlbi(op, arg);					\
> +		break
> +
> +static __always_inline void __tlbi_level_op(const enum tlbi_op op, u64 arg)
> +{
> +	switch (op) {
> +	__GEN_TLBI_OP_CASE(vae1is);
> +	__GEN_TLBI_OP_CASE(vae2is);
> +	__GEN_TLBI_OP_CASE(vale1is);
> +	__GEN_TLBI_OP_CASE(vale2is);
> +	__GEN_TLBI_OP_CASE(vaale1is);
> +	__GEN_TLBI_OP_CASE(ipas2e1);
> +	__GEN_TLBI_OP_CASE(ipas2e1is);
> +	default:
> +		BUILD_BUG();
> +	}
> +}
> +#undef __GEN_TLBI_OP_CASE
> +
>  #define __tlbi_level(op, addr, level) do {				\
>  	u64 arg = addr;							\
>  									\
> @@ -116,7 +147,7 @@ static inline unsigned long get_trans_granule(void)
>  		arg |= FIELD_PREP(TLBI_TTL_MASK, ttl);			\
>  	}								\
>  									\
> -	__tlbi(op, arg);						\
> +	__tlbi_level_op(op, arg);					\
>  } while(0)
>  
>  #define __tlbi_user_level(op, arg, level) do {				\