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

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Date:	Tue, 28 Jun 2016 09:35:08 -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

(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?