Re: [PATCH v4 14/17] x86/asm/entry/64: Migrate error and interrupt exit work to C

Borislav Petkov
2015-07-02T16:34:12Z

On Thu, Jul 02, 2015 at 09:09:23AM -0700, Andy Lutomirski wrote:
> You mean link-time asm optimizations? Turning off frame pointers in
> leaf functions as long as rbp is still preserved might not be so
> terrible either.

Is there a gcc switch for that?

> I'm torn on this one. In principle, you're right, or we could have a
> macro CALL_ENTER_FROM_USER_MODE that does nothing if context tracking
> is off. OTOH, that's also kind of messy.

Yeah, I'm torn too.

If you have something better, cool. Otherwise it is a judgement call for
tip people.

> If we move even more of this stuff into C, then this problem goes
> away. "call enter_from_user_mode" turns into "enter_from_user_mode()"
> or similar.

... and that should be optimized away, I'd guess, if the body's empty.
Something like empty body removal or whatever...

--
Regards/Gruss,
Boris.

ECO tip #101: Trim your mails when you reply.
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