linux-kernel - Re: [PATCH v6 1/5] arm64: cpufeature: add FEAT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aKBl2UjCM7NRKM+G@e129823.arm.com>
Date: Sat, 16 Aug 2025 12:04:57 +0100
From: Yeoreum Yun <yeoreum.yun@....com>
To: Catalin Marinas <catalin.marinas@....com>
Cc: will@...nel.org, broonie@...nel.org, maz@...nel.org,
	oliver.upton@...ux.dev, shameerali.kolothum.thodi@...wei.com,
	joey.gouly@....com, james.morse@....com, ardb@...nel.org,
	scott@...amperecomputing.com, suzuki.poulose@....com,
	yuzenghui@...wei.com, mark.rutland@....com,
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 1/5] arm64: cpufeature: add FEAT_LSUI

Hi Catalin,

> On Mon, Aug 11, 2025 at 05:36:31PM +0100, Yeoreum Yun wrote:
> > @@ -3131,6 +3132,13 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
> >  		.matches = has_cpuid_feature,
> >  		ARM64_CPUID_FIELDS(ID_AA64PFR2_EL1, GCIE, IMP)
> >  	},
> > +	{
> > +		.desc = "Unprivileged Load Store Instructions (LSUI)",
> > +		.capability = ARM64_HAS_LSUI,
> > +		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
> > +		.matches = has_cpuid_feature,
> > +		ARM64_CPUID_FIELDS(ID_AA64ISAR3_EL1, LSUI, IMP)
> > +	},
> >  	{},
> >  };
>
> Since this is only used in the kernel, I wonder whether we should hide
> it behind #ifdef CONFIG_AS_HAS_LSUI. Otherwise we report it as present
> and one may infer that the kernel is going to use it. Not a strong view
> and I don't think we have a precedent for this.

Agree, anyway if CONFIG_AS_HAS_LSUI, it'll be not used anywhere
right now though kernel report it has this feature.

I'll wrap it as your suggestion.

Thanks.

--
Sincerely,
Yeoreum Yun