linux-kernel - Re: [PATCH 1/1] x86_64: fix early_gdt_descr

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Message-ID: <73c1f2160902071243t1c00ad1fqf1ae286995f1c1d9@mail.gmail.com>
Date:	Sat, 7 Feb 2009 15:43:14 -0500
From:	Brian Gerst <brgerst@...il.com>
To:	Jiri Slaby <jirislaby@...il.com>
Cc:	mingo@...hat.com, tglx@...utronix.de, hpa@...or.com, pavel@...e.cz,
	rjw@...k.pl, linux-kernel@...r.kernel.org,
	Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 1/1] x86_64: fix early_gdt_descr_base mangling

On Sat, Feb 7, 2009 at 12:40 PM, Jiri Slaby <jirislaby@...il.com> wrote:
> Commit 8c7e58e690ae60ab4215b025f433ed4af261e103
> (x86: rework __per_cpu_load adjustments)
> has broken resume on my machine. On every secondary_startup_64 invocation,
> it adds initial_gs to early_gdt_descr_base.
>
> Fix it by initializing it to per_cpu__gdt_page and adding to it.
>
> Signed-off-by: Jiri Slaby <jirislaby@...il.com>
> Cc: Brian Gerst <brgerst@...il.com>
> Cc: Tejun Heo <tj@...nel.org>
> ---
>  arch/x86/kernel/head_64.S |    5 +++--
>  1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
> index a0a2b5c..dadca8d 100644
> --- a/arch/x86/kernel/head_64.S
> +++ b/arch/x86/kernel/head_64.S
> @@ -215,7 +215,8 @@ ENTRY(secondary_startup_64)
>        movq    initial_gs(%rip), %rax
>        cmpl    $0, per_cpu__cpu_number(%rax)
>        jne     1f
> -       addq    %rax, early_gdt_descr_base(%rip)
> +       addq    $per_cpu__gdt_page, %rax
> +       movq    %rax, early_gdt_descr_base(%rip)
>  1:
>  #endif
>        /*
> @@ -425,7 +426,7 @@ NEXT_PAGE(level2_spare_pgt)
>  early_gdt_descr:
>        .word   GDT_ENTRIES*8-1
>  early_gdt_descr_base:
> -       .quad   per_cpu__gdt_page
> +       .quad   0

The add of the load address isn't done on UP, so this breaks it.

Actually, hold off on this patch.  I see a better way of handling this.

--
Brian Gerst
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