linux-kernel - Re: [PATCH v11 RESEND 4/9] arm64: Kconfig: Detect toolchain support for LSUI

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Message-ID: <aW5S04xS4FT0zvXv@willie-the-truck>
Date: Mon, 19 Jan 2026 15:50:43 +0000
From: Will Deacon <will@...nel.org>
To: Yeoreum Yun <yeoreum.yun@....com>
Cc: catalin.marinas@....com, maz@...nel.org, broonie@...nel.org,
	oliver.upton@...ux.dev, miko.lenczewski@....com,
	kevin.brodsky@....com, ardb@...nel.org, suzuki.poulose@....com,
	lpieralisi@...nel.org, yangyicong@...ilicon.com,
	scott@...amperecomputing.com, joey.gouly@....com,
	yuzenghui@...wei.com, pbonzini@...hat.com, shuah@...nel.org,
	mark.rutland@....com, arnd@...db.de,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	kvmarm@...ts.linux.dev, kvm@...r.kernel.org,
	linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v11 RESEND 4/9] arm64: Kconfig: Detect toolchain support
 for LSUI

On Sun, Dec 14, 2025 at 11:22:43AM +0000, Yeoreum Yun wrote:
> Since Armv9.6, FEAT_LSUI supplies the load/store instructions for
> previleged level to access to access user memory without clearing
> PSTATE.PAN bit.
> It's enough to add CONFIG_AS_HAS_LSUI only because the code for LSUI uses
> individual `.arch_extension` entries.
> 
> Signed-off-by: Yeoreum Yun <yeoreum.yun@....com>
> Reviewed-by: Catalin Marinas <catalin.marinas@....com>
> ---
>  arch/arm64/Kconfig | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 93173f0a09c7..36e87a1a1b5c 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -2227,6 +2227,11 @@ config ARM64_GCS
> 
>  endmenu # "ARMv9.4 architectural features"
> 
> +config AS_HAS_LSUI
> +	def_bool $(as-instr,.arch_extension lsui)
> +	help
> +	  Supported by LLVM 20+ and binutils 2.45+.

This is an internal Kconfig variable so please drop the help text.

Will