Messages in this thread | | | Date | Wed, 2 Dec 2020 18:08:23 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH v2 04/12] x86/xen: drop USERGS_SYSRET64 paravirt call |
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On Wed, Dec 02, 2020 at 03:48:21PM +0100, Jürgen Groß wrote: > I wanted to avoid the additional NOPs for the bare metal case.
Yeah, in that case it gets optimized to a single NOP:
[ 0.176692] SMP alternatives: ffffffff81a00068: [0:5) optimized NOPs: 0f 1f 44 00 00
which is nopl 0x0(%rax,%rax,1) and I don't think that's noticeable on modern CPUs where a NOP is basically a rIP increment only and that goes down the pipe almost for free. :-)
> If you don't mind them I can do as you are suggesting.
Yes pls, I think asm readability is more important than a 5-byte NOP.
Thx.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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