Re: [PATCH v2] x86/entry/32: Remove duplicate initialization of tss.ss1

[Ingo Molnar <mingo@kernel.org>]

* Andy Lutomirski <luto@amacapital.net> wrote:

> On Sun, Aug 23, 2015 at 4:26 AM, Ingo Molnar <mingo@kernel.org> wrote:
> >
> > * Andy Lutomirski <luto@kernel.org> wrote:
> >
> >> It's statically initialized, so we don't need to dynamically
> >> initialize it too.
> >>
> >> Reported-by: Brian Gerst <brgerst@gmail.com>
> >> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> >> ---
> >>
> >> Changes since v1: Delete the code :)
> >>
> >> arch/x86/kernel/cpu/common.c | 8 --------
> >>  1 file changed, 8 deletions(-)
> >>
> >> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> >> index e2ed2513a51e..e08eee98a5f8 100644
> >> --- a/arch/x86/kernel/cpu/common.c
> >> +++ b/arch/x86/kernel/cpu/common.c
> >> @@ -1005,14 +1005,6 @@ void enable_sep_cpu(void)
> >>       if (IS_ENABLED(CONFIG_X86_32) && !boot_cpu_has(X86_FEATURE_SEP))
> >>               goto out;
> >>
> >> -#ifdef CONFIG_X86_32
> >> -     /*
> >> -      * We cache MSR_IA32_SYSENTER_CS's value in the TSS's ss1 field --
> >> -      * see the big comment in struct x86_hw_tss's definition.
> >> -      */
> >> -     tss->x86_tss.ss1 = __KERNEL_CS;
> >> -#endif
> >> -
> >>       wrmsrl_safe(MSR_IA32_SYSENTER_CS, __KERNEL_CS);
> >>       wrmsrl_safe(MSR_IA32_SYSENTER_ESP,
> >>                   (unsigned long)tss +
> >
> > So this code changed substantially in tip:x86/asm - do we still need this patch?
> >
> 
> Yes, although I think it's actually the other way around -- I think
> this patch may have applied on top of something that never made it
> into tip/x86/asm.  I can re-check or I could just rebase the patch (or
> you could apply it with the obvious fixup).

Yeah, so I noticed that it fell amongst the cracks - please incorporate it into 
your next (v4.4 targeted) series once we get to that, so it doesn't get lost.

> It's obviously not a critical fix.

Yeah.

Thanks,

	Ingo