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Date: Tue, 24 May 2016 22:45:51 +0200
From: Emese Revfy <re.emese@gmail.com>
Subject: Re: [PATCH v1 2/3] Mark functions with the latent_entropy attribute
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To: Kees Cook <keescook@chromium.org>
Cc: "kernel-hardening@lists.openwall.com" <kernel-hardening@lists.openwall.com>, PaX Team <pageexec@freemail.hu>, Brad Spengler <spender@grsecurity.net>, Michal Marek <mmarek@suse.com>, LKML <linux-kernel@vger.kernel.org>, Masahiro Yamada <yamada.masahiro@socionext.com>, linux-kbuild <linux-kbuild@vger.kernel.org>, Theodore Ts'o <tytso@mit.edu>, Andrew Morton <akpm@linux-foundation.org>, Linux-MM <linux-mm@kvack.org>, Jens Axboe <axboe@kernel.dk>, Al Viro <viro@zeniv.linux.org.uk>, Paul McKenney <paulmck@linux.vnet.ibm.com>, Ingo Molnar <mingo@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, bart.vanassche@sandisk.com, "David S. Miller" <davem@davemloft.net>

On Tue, 24 May 2016 10:16:09 -0700
Kees Cook <keescook@chromium.org> wrote:

> On Mon, May 23, 2016 at 3:16 PM, Emese Revfy <re.emese@gmail.com> wrote:
> > +#ifdef CONFIG_MEMORY_HOTPLUG
> > +#define add_meminit_latent_entropy
> > +#else
> > +#define add_meminit_latent_entropy __latent_entropy
> > +#endif
> > +
> >  /* These are for everybody (although not all archs will actually
> >     discard it in modules) */
> > -#define __init         __section(.init.text) __cold notrace
> > +#define __init         __section(.init.text) __cold notrace __latent_entropy
> >  #define __initdata     __section(.init.data)
> >  #define __initconst    __constsection(.init.rodata)
> >  #define __exitdata     __section(.exit.data)
> > @@ -92,7 +98,7 @@
> >  #define __exit          __section(.exit.text) __exitused __cold notrace
> >
> >  /* Used for MEMORY_HOTPLUG */
> > -#define __meminit        __section(.meminit.text) __cold notrace
> > +#define __meminit        __section(.meminit.text) __cold notrace add_meminit_latent_entropy
> >  #define __meminitdata    __section(.meminit.data)
> >  #define __meminitconst   __constsection(.meminit.rodata)
> >  #define __memexit        __section(.memexit.text) __exitused __cold notrace
> 
> I was confused by these defines. :) Maybe "add_meminit_latent_entropy"
> should be named "__memory_hotplug_only_latent_entropy" or something
> like that?

I think the plugin doesn't cause a significant slowdown when CONFIG_MEMORY_HOTPLUG is enabled so I would rather always add the __latent_entropy attribute to __meminit.

-- 
Emese

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