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From:   Florian Weimer <fweimer@redhat.com>
To:     Andy Lutomirski <luto@kernel.org>
Cc:     x86@kernel.org, LKML <linux-kernel@vger.kernel.org>,
        Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH] x86/vsyscall: Remove CONFIG_LEGACY_VSYSCALL_EMULATE
References: <898932fe61db6a9d61bc2458fa2f6049f1ca9f5c.1652290558.git.luto@kernel.org>
Date:   Wed, 11 May 2022 20:35:02 +0200
In-Reply-To: <898932fe61db6a9d61bc2458fa2f6049f1ca9f5c.1652290558.git.luto@kernel.org>
        (Andy Lutomirski's message of "Wed, 11 May 2022 10:38:53 -0700")
Message-ID: <87o803dijt.fsf@oldenburg.str.redhat.com>
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* Andy Lutomirski:

> CONFIG_LEGACY_VSYSCALL_EMULATE is, as far as I know, only needed for the
> combined use of exotic and outdated debugging mechanisms with outdated
> binaries.  At this point, no one should be using it.  We would like to
> implement dynamic switching of vsyscalls, but this is much more
> complicated to support in EMULATE mode than XONLY mode.
>
> So let's force all the distros off of EMULATE mode.  If anyone actually
> needs it, they can set vsyscall=emulate, and we can then get away with
> refusing to support newer security models if that option is set.
>
> Cc: x86@kernel.org
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Florian Weimer <fweimer@redhat.com>
> Signed-off-by: Andy Lutomirski <luto@kernel.org>

Sounds a good idea to me.

Acked-by: Florian Weimer <fweimer@redhat.com>

Regarding the mechanics, is it customary to remove the actual code (the
EMULATE enum constant) in later commits?

Thanks,
Florian