From: Alexander Graf <agraf@suse.de>
To: Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Richard Brown <rbrown@suse.de>,
Matthias Brugger <mbrugger@suse.com>,
yousaf.kaukab@suse.com
Subject: Re: [PATCH v2] arm64: Make kpti command line options x86 compatible
Date: Thu, 15 Nov 2018 17:49:31 +0100 [thread overview]
Message-ID: <215607E6-DF71-436C-92FA-AC4716777CA9@suse.de> (raw)
In-Reply-To: <20181115154738.GB2062@brain-police>
> Am 15.11.2018 um 16:47 schrieb Will Deacon <will.deacon@arm.com>:
>
>> On Tue, Nov 13, 2018 at 04:29:06PM +0100, Alexander Graf wrote:
>> I've already stumbled over 2 cases where people got confused about how to
>> disable kpti on AArch64. In both cases, they used existing x86_64 options
>> and just applied that to an AArch64 system, expecting it to work.
>>
>> I think it makes a lot of sense to have compatible kernel command line
>> parameters whenever we can have them be compatible.
>>
>> So this patch adds the pti= and no_pti kernel command line options, mapping
>> them into the existing kpti= command line framework. It preserves the old
>> syntax to maintain compatibility with older command lines.
>>
>> While at it, the patch also marks the respective options as dual-arch.
>>
>> Reported-by: Richard Brown <rbrown@suse.de>
>> Signed-off-by: Alexander Graf <agraf@suse.de>
>>
>> ---
>>
>> v1 -> v2:
>>
>> - Actually make it compile. Sorry for the sloppy v1.
>> ---
>> Documentation/admin-guide/kernel-parameters.txt | 6 +++---
>> arch/arm64/kernel/cpufeature.c | 20 +++++++++++++++++++-
>> 2 files changed, 22 insertions(+), 4 deletions(-)
>
> This patch doesn't help though, right, because kpti= has already been
> included with backports etc so the ship has sailed?
Not necessarily. We can always mark this as stable and have distros pull it in. Consistency is definitely useful for everyone.
> Yeah, it's not ideal,
> but we went over this before:
>
> http://lists.infradead.org/pipermail/linux-arm-kernel/2018-August/598395.html
Ah, I mist havd missed that. But if you already have 2 people sending very similar patches, there is probably something to it :).
>
> The thing we really need is the sysfs interface hooking up so you can easily
> check the state of the mitigation. Still waiting for a follow-up on that ;)
>
> http://lists.infradead.org/pipermail/linux-arm-kernel/2018-September/603412.html
That one is very much needed as well, yes.
Alex
>
> Will
prev parent reply other threads:[~2018-11-15 16:49 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-13 15:29 [PATCH v2] arm64: Make kpti command line options x86 compatible Alexander Graf
2018-11-15 15:47 ` Will Deacon
2018-11-15 16:49 ` Alexander Graf [this message]
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