linux-kernel - Re: [PATCH v1 01/13] arm64: mm: Re-implement the __tlbi

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Message-ID: <20251216175309.00001935@huawei.com>
Date: Tue, 16 Dec 2025 17:53:09 +0000
From: Jonathan Cameron <jonathan.cameron@...wei.com>
To: Ryan Roberts <ryan.roberts@....com>
CC: Will Deacon <will@...nel.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>, Dev Jain
	<dev.jain@....com>, Linu Cherian <Linu.Cherian@....com>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 01/13] arm64: mm: Re-implement the __tlbi_level macro
 as a C function

On Tue, 16 Dec 2025 14:45:46 +0000
Ryan Roberts <ryan.roberts@....com> wrote:

> As part of efforts to reduce our reliance on complex preprocessor macros
> for TLB invalidation routines, convert the __tlbi_level macro to a C
> function for by-level TLB invalidation.
> 
> Each specific tlbi level op is implemented as a C function and the
> appropriate function pointer is passed to __tlbi_level(). Since
> everything is declared inline and is statically resolvable, the compiler
> will convert the indirect function call to a direct inline execution.
> 
> Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Signed-off-by: Ryan Roberts <ryan.roberts@....com>
> ---

> +static __always_inline void __tlbi_level(tlbi_op op, u64 addr, u32 level)
> +{
> +	u64 arg = addr;
> +
> +	if (alternative_has_cap_unlikely(ARM64_HAS_ARMv8_4_TTL) && level <= 3) {
> +		u64 ttl = level | (get_trans_granule() << 2);
> +
> +		arg &= ~TLBI_TTL_MASK;
> +		arg |= FIELD_PREP(TLBI_TTL_MASK, ttl);

Probably don't care, but I think you could do
		FIELD_MODIFY(TLBI_TTL_MASK, &arg, ttl);
instead of those two lines. Code generation hopefully similar?
So depends on which macros you find more readable.

> +	}
> +
> +	op(arg);
> +}
>  
>  #define __tlbi_user_level(op, arg, level) do {				\
>  	if (arm64_kernel_unmapped_at_el0())				\