Re: [PATCH v6 5/5] x86/gsseg: use the LKGS instruction if available for load_gs_index()

[Borislav Petkov]

On Sun, Jun 30, 2024 at 07:34:42PM -0700, H. Peter Anvin wrote:
> It is much like "movl %edi,%ds"...

You mean ...,%gs"... :-P

But yeah, that makes more sense.

Are we saying somewhere that when moving into a segreg, only the lower 16 bits
of the source operand are used?

Both docs say

8E /r	MOV Sreg, r/m16		Move r/m16 to segment register.

and I read that strict as r16 so I'd expect a "mov %di,..." not a "mov
%edi,..."

Thx.

-- 
Regards/Gruss,
    Boris.

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