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From:   Sami Tolvanen <samitolvanen@google.com>
Date:   Wed, 12 Feb 2020 09:30:49 -0800
Message-ID: <CABCJKucpq=zu7ikf+Q-f-v+6T-cbQCEb1setiZfFvHa8iw3erg@mail.gmail.com>
Subject: Re: [PATCH v7 09/11] arm64: disable SCS for hypervisor code
To:     Will Deacon <will@kernel.org>
Cc:     Mark Rutland <mark.rutland@arm.com>,
        James Morse <james.morse@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Dave Martin <Dave.Martin@arm.com>,
        Kees Cook <keescook@chromium.org>,
        Laura Abbott <labbott@redhat.com>,
        Marc Zyngier <maz@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Jann Horn <jannh@google.com>,
        Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        Kernel Hardening <kernel-hardening@lists.openwall.com>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Tue, Feb 11, 2020 at 1:54 AM Will Deacon <will@kernel.org> wrote:
> Thanks, I missed that. It's annoying that we'll end up needing /both/
> -ffixed-x18 *and* the save/restore around guest transitions, but if we
> actually want to use SCS for the VHE code then I see that it will be
> required.
>
> Sami -- can you restore -ffixed-x18 and then try the function attribute
> as suggested by James, please?

Sure. Adding __noscs to __hyp_text and not filtering out any of the
flags in the Makefile appears to work. I'll update this in the next
version.

Sami