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Date: Thu, 16 Nov 2017 08:25:18 -0800
From: Sami Tolvanen <samitolvanen@google.com>
To: Will Deacon <will.deacon@arm.com>
Cc: Alex Matveev <alxmtvv@gmail.com>, Andi Kleen <ak@linux.intel.com>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
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        Masahiro Yamada <yamada.masahiro@socionext.com>,
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Subject: Re: [PATCH v2 06/18] arm64: kvm: use -fno-jump-tables with clang
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 <20171116114616.GC9361@arm.com>
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On Thu, Nov 16, 2017 at 11:46:17AM +0000, Will Deacon wrote:
> Can you elaborate a bit more on exactly what you saw failing here,
> please?

Mark noticed that clang built kernels fail to boot when the kernel
starts at EL2:

  http://lkml.iu.edu/hypermail/linux/kernel/1711.0/02817.html

Turns out starting with LLVM r308050, the compiler decides to use
a jump table in __init_stage2_translation, and generates code that
branches into an EL1 virtual address.

> Whilst it's obviously broken to jump to EL1 from EL2 w/o VHE, the
> commit message is a bit cryptic.

I agree, I'll add a more descriptive commit message for v3.

Sami