linux-kernel - Re: [PATCH v1 0/2] Introduce the initify gcc plugin

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Date:	Tue, 28 Jun 2016 11:48:54 -0700
From:	Joe Perches <joe@...ches.com>
To:	Emese Revfy <re.emese@...il.com>,
	kernel-hardening@...ts.openwall.com,
	Mathias Krause <minipli@...glemail.com>
Cc:	pageexec@...email.hu, spender@...ecurity.net, mmarek@...e.com,
	keescook@...omium.org, linux-kernel@...r.kernel.org,
	yamada.masahiro@...ionext.com, linux-kbuild@...r.kernel.org,
	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, arnd@...db.de
Subject: Re: [PATCH v1 0/2] Introduce the initify gcc plugin

On Tue, 2016-06-28 at 09:35 -0700, Joe Perches wrote:
> (adding Mathias Krause who did something similar via macros in 2014)
> 
> https://lkml.org/lkml/2014/6/22/149
> 
> On Tue, 2016-06-28 at 13:34 +0200, Emese Revfy wrote:
> > 
> > I would like to introduce the initify gcc plugin. 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. It reduces memory usage.
> > The initify gcc plugin can be useful for embedded systems.
> What happens to string deduplication when one string
> is in an init function and the same string is also used
> in a non-init function in the same compilation unit?
> 
> foo.c
> 
> __init void initfunc(void)
> {
> 	pr_info("%s: I'm here\n", __func__);
> }
> 
> void runtimefunc(void)
> {
> 	pr_info("I'm here: %s\n", __func__);
> }
> 
> In what section does the string "I'm here: %s\n" get placed
> or does it get placed into multiple sections?

Sorry, Joe can't type.
That was meant to be the identical string in both functions.