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From:   Sami Tolvanen <samitolvanen@google.com>
Date:   Thu, 16 Jan 2020 12:16:53 -0800
Message-ID: <CABCJKucQY_Qr6bZXW5TdPnDcBUd7uk8_Md5FNfO+ObNmsH3MZg@mail.gmail.com>
Subject: Re: [PATCH v6 13/15] arm64: disable SCS for hypervisor code
To:     Will Deacon <will@kernel.org>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Mark Rutland <mark.rutland@arm.com>,
        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 Thu, Jan 16, 2020 at 9:47 AM Will Deacon <will@kernel.org> wrote:
>
> On Fri, Dec 06, 2019 at 02:13:49PM -0800, Sami Tolvanen wrote:
> > Filter out CC_FLAGS_SCS for code that runs at a different exception
> > level.
> >
> > Suggested-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
> > Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> > Reviewed-by: Kees Cook <keescook@chromium.org>
> > Reviewed-by: Mark Rutland <mark.rutland@arm.com>
> > ---
> >  arch/arm64/kvm/hyp/Makefile | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile
> > index ea710f674cb6..17ea3da325e9 100644
> > --- a/arch/arm64/kvm/hyp/Makefile
> > +++ b/arch/arm64/kvm/hyp/Makefile
> > @@ -28,3 +28,6 @@ GCOV_PROFILE        := n
> >  KASAN_SANITIZE       := n
> >  UBSAN_SANITIZE       := n
> >  KCOV_INSTRUMENT      := n
> > +
> > +# remove the SCS flags from all objects in this directory
> > +KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS))
>
> Same comment as for the vDSO; can we remove the -ffixed-x18 as well?

Sure, I don't see why not. I'll change this in the next version.

Sami