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Message-ID: <1534448697.6862.60.camel@infradead.org>
Subject: Re: [PATCH] x86/vdso: Fix vDSO build if a retpoline is emitted
From:   David Woodhouse <dwmw2@infradead.org>
To:     Andy Lutomirski <luto@kernel.org>, x86@kernel.org,
        LKML <linux-kernel@vger.kernel.org>
Cc:     Borislav Petkov <bp@alien8.de>,
        Matt Rickard <matt@softrans.com.au>,
        Jason Vas Dias <jason.vas.dias@gmail.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Andi Kleen <ak@linux.intel.com>
In-Reply-To: <c76538cd3afbe19c6246c2d1715bc6a60bd63985.1534448381.git.luto@kernel.org>
References: <c76538cd3afbe19c6246c2d1715bc6a60bd63985.1534448381.git.luto@kernel.org>
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Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-oID3vmPqOXmOhLwK9f0D"
Date:   Thu, 16 Aug 2018 21:44:57 +0200
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Sender: linux-kernel-owner@vger.kernel.org
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On Thu, 2018-08-16 at 12:41 -0700, Andy Lutomirski wrote:
> Currently, if the vDSO ends up containing an indirect branch or
> call, GCC will emit the "external thunk" style of retpoline, and it
> will fail to link.
>=20
> Fix it by building the vDSO with inline retpoline thunks.
>=20
> I haven't seen any reports of this triggering on an unpatched
> kernel.
>=20
> Cc: Matt Rickard <matt@softrans.com.au>
> Cc: Jason Vas Dias <jason.vas.dias@gmail.com>
> Cc: David Woodhouse <dwmw2@infradead.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Andi Kleen <ak@linux.intel.com>
> Fixes: commit 76b043848fd2 ("x86/retpoline: Add initial retpoline support=
")
> Signed-off-by: Andy Lutomirski <luto@kernel.org>

Acked-by: David Woodhouse <dwmw@amazon.co.uk>

Thanks.
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