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From: Ingo Molnar <mingo@kernel.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andy Lutomirski <luto@amacapital.net>,
	Denys Vlasenko <dvlasenk@redhat.com>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] Drop some asm from copy_user_64.S
Date: Wed, 13 May 2015 12:46:30 +0200	[thread overview]
Message-ID: <20150513104630.GA7751@gmail.com> (raw)
In-Reply-To: <20150513104330.GG1517@pd.tnic>


* Borislav Petkov <bp@alien8.de> wrote:

> On Wed, May 13, 2015 at 12:31:40PM +0200, Ingo Molnar wrote:
> > So why should an alternatives-CALL, inlined directly into call sites,
> > cost more kernel space?
> 
> Not the alternatives CALL alone but inlining _copy_*_user with all 
> the preparation glue around it would. Basically what we're doing 
> currently.

So I reacted to this comment of yours:

> > > The disadvantage is that we have CALL after CALL [...]

Is the CALL after CALL caused by us calling an alternatives patched 
function? If yes then we probably should not do that: alternatives 
switching should IMHO happen at the highest possible level.

Thanks,

	Ingo

  reply	other threads:[~2015-05-13 10:46 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-12 20:57 [RFC PATCH] Drop some asm from copy_user_64.S Borislav Petkov
2015-05-12 21:13 ` Linus Torvalds
2015-05-12 21:53   ` Borislav Petkov
2015-05-13  9:52     ` Borislav Petkov
2015-05-13 10:31       ` Ingo Molnar
2015-05-13 10:43         ` Borislav Petkov
2015-05-13 10:46           ` Ingo Molnar [this message]
2015-05-13 11:16             ` Borislav Petkov
2015-05-13 16:02       ` Linus Torvalds
2015-05-14  9:36         ` Borislav Petkov
2015-05-13  6:19 ` Ingo Molnar
2015-05-13 10:28   ` Borislav Petkov

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