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From:   Andy Lutomirski <luto@amacapital.net>
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Subject: Re: objtool clac/stac handling change..
Date:   Wed, 1 Jul 2020 20:08:36 -0700
Message-Id: <B9CF61D4-50F7-4A82-8327-86CA18450669@amacapital.net>
References: <CAHk-=wjXftMyC93Jg8J=_HiuERsHujPOa-RbOmMLuuxVoJCrfQ@mail.gmail.com>
Cc:     Andy Lutomirski <luto@kernel.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        the arch/x86 maintainers <x86@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
In-Reply-To: <CAHk-=wjXftMyC93Jg8J=_HiuERsHujPOa-RbOmMLuuxVoJCrfQ@mail.gmail.com>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Sender: linux-kernel-owner@vger.kernel.org
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> On Jul 1, 2020, at 7:30 PM, Linus Torvalds <torvalds@linux-foundation.org>=
 wrote:
>=20
> =EF=BB=BFOn Wed, Jul 1, 2020 at 5:48 PM Andy Lutomirski <luto@kernel.org> w=
rote:
>>=20
>> You inspired me to mock it up.
>=20
> Ahh, you want to just use the jump folding of gcc to avoid the problem.
>=20
> I guess we could do that. Are there cases where this actually helps?
>=20

I was thinking it would help avoid brain melt. For better or for worse, the k=
ernel is written in C, and readers don=E2=80=99t really expect call_some_fun=
ction(arg, other arg) to actually teleport elsewhere in the function.  I=E2=80=
=99m all for goto err; but at least that=E2=80=99s spelled =E2=80=9Cgoto=E2=80=
=9D and it=E2=80=99s really obvious what it does.=