linux-kernel - Re: [RFC PATCH] Drop some asm from copy_user

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Message-ID: <CA+55aFwZ4xTtvT8JX_T8RVVJD88L2hrE3HK0o-tt8BK=7T_4Aw@mail.gmail.com>
Date:	Tue, 12 May 2015 14:13:33 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Borislav Petkov <bp@...en8.de>
Cc:	Ingo Molnar <mingo@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andy Lutomirski <luto@...capital.net>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] Drop some asm from copy_user_64.S

On Tue, May 12, 2015 at 1:57 PM, Borislav Petkov <bp@...en8.de> wrote:
>
> I want to get rid of the asm glue in arch/x86/lib/copy_user_64.S which
> prepares the copy_user* alternatives calls. And replace it with nice and
> clean C.

Ack. I'm not a fan of the x86-64 usercopy funmctions.

That said, I think you should uninline those things, and move them
from a header file to a C file (arch/x86/lib/uaccess.c?).

Move all the copy_user_generic_unrolled/string garbage there too, and
keep the header file simple.

Because I think that we would actually be better off trying to inline
the copy_user_generic_string() thing into the various versions (in
that uaccess.c file) than try to inline the access_ok() check into the
caller.

                           Linus
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