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 <CANiq72kXoonDYk095XvBwEtRCRNECd1iQOqJHE2cNcgLyUMfcQ@mail.gmail.com> <202202251258.DB0F403B@keescook>
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From:   Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Date:   Sat, 26 Feb 2022 02:27:53 +0100
Message-ID: <CANiq72=KjCd8pWKuXFzoW7oBQM9DV=DDyGzCyz62F4B+e5Q_qg@mail.gmail.com>
Subject: Re: [PATCH] [PATCH v2] AARCH64: Add gcc Shadow Call Stack support
To:     Kees Cook <keescook@chromium.org>
Cc:     Dan Li <ashimida@linux.alibaba.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Sami Tolvanen <samitolvanen@google.com>,
        Nicholas Piggin <npiggin@gmail.com>,
        Guenter Roeck <linux@roeck-us.net>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Miguel Ojeda <ojeda@kernel.org>,
        Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
        Marco Elver <elver@google.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        llvm@lists.linux.dev, linux-hardening@vger.kernel.org
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On Fri, Feb 25, 2022 at 9:59 PM Kees Cook <keescook@chromium.org> wrote:
>
> I thought about that too, but I think it's less simple due to the
> __has_feature vs CONFIG differences, etc:
> https://lore.kernel.org/lkml/202202251243.1E38256F9@keescook/
>
> But maybe __has_feature doesn't really matter here?

I have not tested it, but I was assuming the `CONFIG` could do its
job, since it comes from testing the compiler flag.

If the `__has_feature` is actually restricting it more than that, then
we should probably get the `CONFIG` fixed so that it only gets enabled
when really it is going to be used.

Cheers,
Miguel