Re: [PATCH 09/43] x86/entry: Move SYSENTER_stack to the beginning of struct tss_struct

[Borislav Petkov]

On Fri, Nov 24, 2017 at 10:14:14AM +0100, Ingo Molnar wrote:
> From: Andy Lutomirski <luto@xxxxxxxxxx>
> 
> SYSENTER_stack should have reliable overflow detection, which
> means that it needs to be at the bottom of a page, not the top.
> Move it to the beginning of struct tss_struct and page-align it.
> 
> Also add an assertion to make sure that the fixed hardware TSS
> doesn't cross a page boundary.
> 
> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxxxx>
> Cc: Borislav Petkov <bpetkov@xxxxxxx>
> Cc: Brian Gerst <brgerst@xxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
> Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
> Cc: H. Peter Anvin <hpa@xxxxxxxxx>
> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Link: http://lkml.kernel.org/r/8de9901e7c3a6aa8fac95b37b9c7b96f1900f11a.1511497875.git.luto@xxxxxxxxxx
> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
> ---
>  arch/x86/include/asm/processor.h | 21 ++++++++++++---------
>  arch/x86/kernel/cpu/common.c     | 21 +++++++++++++++++++++
>  2 files changed, 33 insertions(+), 9 deletions(-)

Reviewed-by: Borislav Petkov <bp@xxxxxxx>

Thanks to tglx for clarifying the whole top and bottom meaning here for
me - I was confused.

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.