linux-kernel - Re: [PATCH v3] arm64: Add support for new control bits CTR_EL0.DIC and CTR

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] [day] [month] [year] [list]

Message-ID: <20180222113818.6cknpwfbed2ab2nd@lakrids.cambridge.arm.com>
Date:   Thu, 22 Feb 2018 11:38:19 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Robin Murphy <robin.murphy@....com>
Cc:     shankerd@...eaurora.org, Philip Elcan <pelcan@...eaurora.org>,
        Vikram Sethi <vikrams@...eaurora.org>,
        Marc Zyngier <marc.zyngier@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        kvmarm <kvmarm@...ts.cs.columbia.edu>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3] arm64: Add support for new control bits CTR_EL0.DIC
 and CTR_EL0.IDC

On Wed, Feb 21, 2018 at 04:51:40PM +0000, Robin Murphy wrote:
> On 21/02/18 16:14, Shanker Donthineni wrote:
> [...]
> > > > @@ -1100,6 +1114,20 @@ static int cpu_copy_el2regs(void *__unused)
> > > >   		.enable = cpu_clear_disr,
> > > >   	},
> > > >   #endif /* CONFIG_ARM64_RAS_EXTN */
> > > > +#ifdef CONFIG_ARM64_SKIP_CACHE_POU
> > > > +	{
> > > > +		.desc = "DCache clean to POU",
> > > 
> > > This description is confusing, and sounds like it's describing DC CVAU, rather
> > > than the ability to ellide it. How about:
> > 
> > Sure, I'll take your suggestion.
> 
> Can we at least spell "elision" correctly please? ;)

Argh. Yes.

> Personally I read DIC and IDC as "D-cache to I-cache coherency" and "I-cache
> to D-cache coherency" respectively (just my interpretation, I've not looked
> into the spec work for any hints of rationale), but out loud those do sound
> so poorly-defined that keeping things in terms of the required maintenance
> probably is better.

So long as we have (IDC) and (DIC) in the text to avoid ambiguity, I'm
not that worried either way.

Thanks,
Mark.