linux-kernel - Re: arm64 kvm built with clang doesn't boot

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Date:   Mon, 19 Mar 2018 17:42:49 +0000
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     marc.zyngier@....com
Cc:     Andrey Konovalov <andreyknvl@...gle.com>,
        Stephen Hines <srhines@...gle.com>,
        Greg Hackmann <ghackmann@...gle.com>,
        Christoffer Dall <christoffer.dall@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        LKML <linux-kernel@...r.kernel.org>,
        Mark Rutland <mark.rutland@....com>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Takahiro Akashi <takahiro.akashi@...aro.org>,
        Robin Murphy <robin.murphy@....com>, dave.martin@....com,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: Re: arm64 kvm built with clang doesn't boot

The thread I was thinking of is:
http://lists.infradead.org/pipermail/linux-arm-kernel/2018-March/562953.html
which is about b092201e0020614127f495c092e0a12d26a2116e `arm64: Add
ARM_SMCCC_ARCH_WORKAROUND_1 BP hardening support`.  As you mention, that
commit uses the correct widths.
Andrey had sent me his workaround, which modified some #defines in
include/linux/arm-smccc.h, which were added recently in commit
f2d3b2e8759a5833df6f022e42df2d581e6d843c `arm/arm64: smccc: Implement SMCCC
v1.1 inline primitive`.

>>> We probably want to be very explicit with register widths here.

So f2d3b2e8759 is the patch I'm referring to.

On Fri, Mar 16, 2018 at 10:18 AM Marc Zyngier <marc.zyngier@....com> wrote:

> On 16/03/18 16:52, Nick Desaulniers wrote:

> [dropping kernel-dynamic-tools@...gle.com which keeps bouncing]

> > Is this in regards to: commit "arm64: Add ARM_SMCCC_ARCH_WORKAROUND_1 BP
> > hardening support"? Has anyone tried to upstream a fix for this?  We
> > probably want to be very explicit with register widths here.
> What do you mean? The current code is as strict as it gets, and
> explicitly tells the compiler to use the right register width, based on
> the SMC call parameter types.

> Thanks,

>          M.
> --
> Jazz is not dead. It just smells funny...



--
Thanks,
~Nick Desaulniers