linux-kernel - Re: [kernel-hardening] [PATCH v5 1/4] gcc-plugins: Add the initify gcc plugin

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Message-Id: <1a252726-5b0f-1cd9-708e-71844df82386@au1.ibm.com>
Date:   Tue, 28 Mar 2017 14:03:24 +1100
From:   Andrew Donnellan <andrew.donnellan@....ibm.com>
To:     Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org
Cc:     Emese Revfy <re.emese@...il.com>, Arnd Bergmann <arnd@...db.de>,
        Josh Triplett <josh@...htriplett.org>, pageexec@...email.hu,
        yamada.masahiro@...ionext.com, minipli@...linux.so,
        linux@...linux.org.uk, catalin.marinas@....com,
        linux@...musvillemoes.dk, david.brown@...aro.org,
        benh@...nel.crashing.org, tglx@...utronix.de,
        akpm@...ux-foundation.org, jlayton@...chiereds.net,
        sam@...nborg.org, kernel-hardening@...ts.openwall.com,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [kernel-hardening] [PATCH v5 1/4] gcc-plugins: Add the initify
 gcc plugin

On 27/03/17 18:38, Andrew Donnellan wrote:
> On 01/02/17 07:24, Kees Cook wrote:
>> From: Emese Revfy <re.emese@...il.com>
>>
>> The kernel already has a mechanism to free up code and data memory that
>> is only used during kernel or module initialization.  This plugin will
>> teach the compiler to find more such code and data that can be freed
>> after initialization.
>
> Currently checking whether we can wire this up for powerpc without too
> many problems...

Added "select HAVE_GCC_PLUGIN_INITIFY_INIT_EXIT if GCC_PLUGINS" to 
arch/powerpc/Kconfig and have successfully compiled and booted a modular 
and non-modular powernv_defconfig, it looks like we handle the .exit 
sections correctly.

Could this be folded in for further testing when you get around to v6, Kees?

-- 
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@....ibm.com  IBM Australia Limited