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Date: Wed, 13 Jul 2016 23:26:14 +0200
From: Emese Revfy <re.emese@...il.com>
To: Kees Cook <keescook@...omium.org>
Cc: Russell King - ARM Linux <linux@...linux.org.uk>,
 "kernel-hardening@...ts.openwall.com"
 <kernel-hardening@...ts.openwall.com>, PaX Team <pageexec@...email.hu>,
 Brad Spengler <spender@...ecurity.net>, Michal Marek <mmarek@...e.com>,
 LKML <linux-kernel@...r.kernel.org>, Masahiro Yamada
 <yamada.masahiro@...ionext.com>, linux-kbuild
 <linux-kbuild@...r.kernel.org>, minipli@...linux.so, Catalin Marinas
 <catalin.marinas@....com>, Rasmus Villemoes <linux@...musvillemoes.dk>,
 David Brown <david.brown@...aro.org>, "benh@...nel.crashing.org"
 <benh@...nel.crashing.org>, Thomas Gleixner <tglx@...utronix.de>, Andrew
 Morton <akpm@...ux-foundation.org>, Jeff Layton <jlayton@...chiereds.net>,
 Arnd Bergmann <arnd@...db.de>, Sam Ravnborg <sam@...nborg.org>, Karsten
 Keil <isdn@...ux-pingi.de>
Subject: Re: [PATCH v2 1/3] Add the initify gcc plugin

On Tue, 12 Jul 2016 18:38:47 -0400
Kees Cook <keescook@...omium.org> wrote:

> On Tue, Jul 12, 2016 at 6:08 PM, Russell King - ARM Linux
> <linux@...linux.org.uk> wrote:
> > On Tue, Jul 12, 2016 at 03:45:56PM -0400, Kees Cook wrote:
> >> On Mon, Jul 4, 2016 at 7:40 PM, Emese Revfy <re.emese@...il.com> wrote:
> > That sounds like a problem for architectures that still discard the
> > __exit section at link time to reduce the size of the linked kernel
> > image - though, obviously, if using the plugin results in a smaller
> > kernel image _with_ the exit sections, then there's a net benefit
> > size-wise.
> 
> Ah right, __exit is dropped for non-modular builds. So, for "both
> __init and __exit" it sounds like the behavior depends on the build:
> 
> - if modular: remove __init marking (since we need it after init)
> - if non-modular: remove __exit marking (since we'll never call exit)

When gcc compiles vmlinux these functions should be in __init and when
it compiles *.ko then they can be in __exit. I have no time to do this
now but I added it to my todo list.

The temporary fix can be that I enable this section move only on x86
(on other archs it will decrase the coverage).

-- 
Emese

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