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From:   Thomas Garnier <thgarnie@chromium.org>
Date:   Fri, 1 Feb 2019 09:13:58 -0800
Message-ID: <CAJcbSZFvafvNX1pS96jaTBGNJad+NszLwSgKnRQgyT70gUGWqQ@mail.gmail.com>
Subject: Re: [PATCH v6 14/27] x86/percpu: Adapt percpu for PIE support
To:     Christopher Lameter <cl@linux.com>
Cc:     Kernel Hardening <kernel-hardening@lists.openwall.com>,
        kristen@linux.intel.com, Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
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        "the arch/x86 maintainers" <x86@kernel.org>,
        Dennis Zhou <dennis@kernel.org>, Tejun Heo <tj@kernel.org>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Juergen Gross <jgross@suse.com>,
        Stefano Stabellini <sstabellini@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andi Kleen <ak@linux.intel.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
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        Mike Rapoport <rppt@linux.vnet.ibm.com>,
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On Thu, Jan 31, 2019 at 6:31 PM Christopher Lameter <cl@linux.com> wrote:
>
> On Thu, 31 Jan 2019, Thomas Garnier wrote:
>
> > The per-cpu symbols are in a section that is zero based to create
> > offsets. The compiler doesn't see them as offsets but as relative
> > symbol and try to relocate them. Given the distance between zero and
> > the mapped kernel is much larger than the instruction offset range, it
> > fails to do it.
>
> We switch that off in the linker. If that does not work with your
> modifications then you need to figure out how to update the link
> configuration.
>

It didn't work originally but I will revisit to see if I missed something.