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From: Jon Masters <jcm@redhat.com>
To: Will Deacon <will.deacon@arm.com>,
	Catalin Marinas <catalin.marinas@arm.com>
Cc: Kristina Martsenko <kristina.martsenko@arm.com>,
	Mark Rutland <Mark.Rutland@arm.com>,
	"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
	Andrew Jones <drjones@redhat.com>,
	Jacob Bramley <Jacob.Bramley@arm.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Marc Zyngier <Marc.Zyngier@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Adam Wallis <awallis@codeaurora.org>,
	Suzuki Poulose <Suzuki.Poulose@arm.com>,
	Christoffer Dall <Christoffer.Dall@arm.com>,
	Dave P Martin <Dave.Martin@arm.com>,
	Amit Kachhap <Amit.Kachhap@arm.com>,
	Ramana Radhakrishnan <ramana.radhakrishnan@foss.arm.com>,
	"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH v5 11/17] arm64: docs: document pointer authentication
Date: Fri, 2 Nov 2018 02:02:03 -0400	[thread overview]
Message-ID: <d73e8824-bb8e-8172-4541-9be136453020@redhat.com> (raw)
In-Reply-To: <20181019174524.GC4429@brain-police>

On 10/19/18 1:45 PM, Will Deacon wrote:

>>> I think an alternative solution is to just disable trapping of pointer
>>> auth instructions in KVM. This will mean that the instructions will
>>> behave the same in the guest as they do in the host. HINT-space
>>> instructions (including XPACLRI) will behave as NOPs (or perform their
>>> function, if enabled by the guest), and will not trap.
>>
>> OK, so this means disabling the trap (during early EL2 setup) but still
>> sanitizing the CPUID not to report the feature to EL1 unless fully
>> supported on all CPUs.
> 
> ... which is perfectly sensible, but not actually my main concern here.
> I'm worried about the possibility of distributions shipping *now* with
> userspace that's built with these instructions. That stuff is going to
> break if/when it encounters v8.3 hardware, and I don't think we can do
> much about it other than alert them to the potential issue.

FYI tracking this for RHEL. It's not a problem currently. I'll alert our
tools teams to hold off on any PAC work until this is figured out.

Jon.

-- 
Computer Architect | Sent with my Fedora powered laptop

  reply	other threads:[~2018-11-02  6:02 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-05  8:47 [PATCH 00/17] ARMv8.3 pointer authentication support Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 01/17] arm64: add pointer authentication register bits Kristina Martsenko
2018-10-11 16:28   ` Will Deacon
2018-10-12  8:53     ` Mark Rutland
2018-10-12  8:56       ` Will Deacon
2018-10-12  9:50         ` Mark Rutland
2018-10-05  8:47 ` [PATCH v5 02/17] arm64/kvm: consistently handle host HCR_EL2 flags Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 03/17] arm64/kvm: hide ptrauth from guests Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 04/17] arm64: Don't trap host pointer auth use to EL2 Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 05/17] arm64/cpufeature: detect pointer authentication Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 06/17] asm-generic: mm_hooks: allow hooks to be overridden individually Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 07/17] arm64: add basic pointer authentication support Kristina Martsenko
2018-10-11 16:00   ` Suzuki K Poulose
2018-10-19 11:15   ` Catalin Marinas
2018-10-19 11:24     ` Will Deacon
2018-10-19 15:36       ` Kees Cook
2018-10-19 15:49         ` Will Deacon
2018-10-19 16:05           ` Kees Cook
2018-10-19 16:16             ` Will Deacon
2018-10-19 15:54         ` Mark Rutland
2018-10-19 16:49       ` Cyrill Gorcunov
2018-11-14 18:11       ` Will Deacon
2018-11-15 10:25         ` Dave Martin
2018-10-23  8:36     ` Ramana Radhakrishnan
2018-10-23 10:20       ` Will Deacon
2018-10-05  8:47 ` [PATCH v5 08/17] arm64: expose user PAC bit positions via ptrace Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 09/17] arm64: perf: strip PAC when unwinding userspace Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 10/17] arm64: enable pointer authentication Kristina Martsenko
2018-10-05  8:47 ` [PATCH v5 11/17] arm64: docs: document " Kristina Martsenko
2018-10-05  9:04   ` Ramana Radhakrishnan
2018-10-16 16:14     ` Kristina Martsenko
2018-10-19 11:35       ` Catalin Marinas
2018-10-19 11:47         ` Marc Zyngier
2018-10-19 12:22         ` Will Deacon
2018-10-19 14:42         ` Kristina Martsenko
2018-10-19 15:10           ` Catalin Marinas
2018-10-19 17:45             ` Will Deacon
2018-11-02  6:02               ` Jon Masters [this message]
2018-10-24 10:56         ` Ramana Radhakrishnan
2018-10-15 22:35   ` Kees Cook
2018-11-02  9:46     ` Ramana Radhakrishnan
2018-10-05  8:47 ` [RFC 12/17] arm64: move ptrauth keys to thread_info Kristina Martsenko
2018-10-19 11:38   ` Catalin Marinas
2018-10-05  8:47 ` [RFC 13/17] arm64: install user ptrauth keys at kernel exit time Kristina Martsenko
2018-10-05  8:47 ` [RFC 14/17] arm64: unwind: strip PAC from kernel addresses Kristina Martsenko
2018-10-05  8:47 ` [RFC 15/17] arm64: enable ptrauth earlier Kristina Martsenko
2018-10-06 12:51   ` Amit Kachhap
2018-10-05  8:47 ` [RFC 16/17] arm64: initialize and switch ptrauth kernel keys Kristina Martsenko
2018-10-06 12:56   ` Amit Kachhap
2018-10-05  8:47 ` [RFC 17/17] arm64: compile the kernel with ptrauth -msign-return-address Kristina Martsenko
2018-10-05  9:01   ` Ramana Radhakrishnan
2018-10-11 14:00     ` Kristina Martsenko
2018-10-11 14:23   ` Vladimir Murzin
2018-10-15 22:38     ` Kees Cook
2018-10-15 22:42 ` [PATCH 00/17] ARMv8.3 pointer authentication support Kees Cook
2018-11-13 16:17   ` Kristina Martsenko
2018-11-13 23:09     ` Kees Cook
2018-11-14 15:54       ` Kristina Martsenko
2018-11-14 21:47       ` Mark Rutland
2018-11-14 22:48         ` Kees Cook
2018-10-19 12:36 ` Will Deacon
2018-10-23  8:39   ` Ramana Radhakrishnan

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