On Wed, Oct 10, 2018 at 11:04:14AM +0800, Feng Tang wrote:
> commit 05ab1d8a4b36ee912b7087c6da127439ed0a903e upstream
>
> We met a kernel panic when enabling earlycon, which is due to the fixmap
> address of earlycon is not statically setup.
>
> Currently the static fixmap setup in head_64.S only covers 2M virtual
> address space, while it actually could be in 4M space with different
> kernel configurations, e.g. when VSYSCALL emulation is disabled.
>
> So increase the static space to 4M for now by defining FIXMAP_PMD_NUM to 2,
> and add a build time check to ensure that the fixmap is covered by the
> initial static page tables.
>
> Fixes: 1ad83c858c7d ("x86_64,vsyscall: Make vsyscall emulation configurable")
> Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # v4.9
> Cc: Juergen Gross <jgross@xxxxxxxx>
> Cc: H Peter Anvin <hpa@xxxxxxxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxxxx>
> Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
> Cc: Andy Lutomirsky <luto@xxxxxxxxxx>
> ---
> arch/x86/include/asm/fixmap.h | 10 ++++++++++
> arch/x86/include/asm/pgtable_64.h | 3 ++-
> arch/x86/kernel/head_64.S | 16 ++++++++++++----
> arch/x86/mm/pgtable.c | 9 +++++++++
> arch/x86/xen/mmu.c | 8 ++++++--
> 5 files changed, 39 insertions(+), 7 deletions(-)
>
Now applied, thanks.
greg k-h
