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

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Message-ID: <87inmujz49.fsf@rasmusvillemoes.dk>
Date:   Mon, 27 Mar 2017 21:31:02 +0200
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     Kees Cook <keescook@...omium.org>
Cc:     Andrew Donnellan <andrew.donnellan@....ibm.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Emese Revfy <re.emese@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        Josh Triplett <josh@...htriplett.org>,
        PaX Team <pageexec@...email.hu>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        minipli@...linux.so, Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        David Brown <david.brown@...aro.org>,
        "benh\@kernel.crashing.org" <benh@...nel.crashing.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jeff Layton <jlayton@...chiereds.net>,
        Sam Ravnborg <sam@...nborg.org>,
        "kernel-hardening\@lists.openwall.com" 
        <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH v5 1/4] gcc-plugins: Add the initify gcc plugin

On Mon, Mar 27 2017, Kees Cook <keescook@...omium.org> wrote:

> On Mon, Mar 27, 2017 at 12:38 AM, Andrew Donnellan
> <andrew.donnellan@....ibm.com> 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...
>
> Cool, thanks. FWIW, note that this plugin is a bit back-burnered at
> the moment. I've got this in my -next tree still, but it needs some
> rather large changes to how it does its annotations before Linus will
> accept it.

Why not just hardcode the annotations in the plugin itself? I'd expect
just making it know about mem*, str*, and the various *printf/printk
functions would get 90% of the benefits. The prototypes of these 
aren't gonna change anytime soon, so there's no compelling reason to
keep the annotations with the declarations. The plugin can still do
its sanity checking when it compiles a function with one of these names.

Rasmus