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From:   Sami Tolvanen <samitolvanen@google.com>
Date:   Thu, 16 Jan 2020 13:45:09 -0800
Message-ID: <CABCJKuduRyBBr1qZQj35nMCOLv3my22wRQXb4-i39n07qdL4Yg@mail.gmail.com>
Subject: Re: [PATCH v6 08/15] arm64: disable function graph tracing with SCS
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 9:39 AM Will Deacon <will@kernel.org> wrote:
>
> On Fri, Dec 06, 2019 at 02:13:44PM -0800, Sami Tolvanen wrote:
> > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > index b1b4476ddb83..49e5f94ff4af 100644
> > --- a/arch/arm64/Kconfig
> > +++ b/arch/arm64/Kconfig
> > @@ -149,7 +149,7 @@ config ARM64
> >       select HAVE_FTRACE_MCOUNT_RECORD
> >       select HAVE_FUNCTION_TRACER
> >       select HAVE_FUNCTION_ERROR_INJECTION
> > -     select HAVE_FUNCTION_GRAPH_TRACER
> > +     select HAVE_FUNCTION_GRAPH_TRACER if !SHADOW_CALL_STACK
> >       select HAVE_GCC_PLUGINS
> >       select HAVE_HW_BREAKPOINT if PERF_EVENTS
> >       select HAVE_IRQ_TIME_ACCOUNTING
>
> I think this is the wrong way around, as we support the graph tracer
> today and so I think SHADOW_CALL_STACK should depend on !GRAPH_TRACER
> and possibly even EXPERT until this is resolved.

Sure, sounds reasonable. I'll change this in the next version.

Sami