Re: [PATCH 5/5] x86/asm/entry/32: Simplify FLAGS_NT clearing in SYSENTER32 code.

[Andy Lutomirski]

On Mon, Jul 27, 2015 at 1:33 PM, Denys Vlasenko <dvlasenk@xxxxxxxxxx> wrote:
> "sysenter_fix_flags" detour does not need to be convoluted anymore,
> straigten it up. However, we still use this:
>
>         jnz     2f
>         jmp     sysenter_jumps_here
> 2:      ...
>
> instead of this:
>
>         jz      sysenter_jumps_here
>         ...
>
> because "cold" conditional forward branch is predicted not taken
> by most CPUs - exactly what we want. Latter version would get it wrong.
>
> Reinstate "why we use SYSRETL instead of SYSEXIT" comment.
>

Acked-by: Andy Lutomirski <luto@xxxxxxxxxx>
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