linux-kernel - Re: [PATCH] x86/boot: Remove x86

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Date:   Tue, 29 Nov 2022 14:26:39 +0100
From:   Uros Bizjak <ubizjak@...il.com>
To:     Brian Gerst <brgerst@...il.com>
Cc:     Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH] x86/boot: Remove x86_32 PIC using ebx workaround

On Tue, Nov 29, 2022 at 2:24 PM Brian Gerst <brgerst@...il.com> wrote:
>
> On Tue, Nov 29, 2022 at 3:32 AM Borislav Petkov <bp@...en8.de> wrote:
> >
> > On Mon, Nov 28, 2022 at 10:41:11PM -0500, Brian Gerst wrote:
> > > x86-64 uses a PIC register for the medium and large PIC code models,
> > > where offsets can be larger than +/- 2GB.
> >
> > Right but 64-bit is built with -mcmodel=kernel which obviously generates
> > rip-relative.
>
> Correct.  He quoted the specific part of the GCC changelog that fixed
> the issue for the 32-bit kernel, but it's not applicable to the 64-bit
> kernel.

It says so right in the summary.

Uros.