linux-kernel - Re: [PATCH 11/18] Hibernate: introduced RSA key-pair to verify signature of snapshot

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Date:	Tue, 27 Aug 2013 16:17:22 +0200
From:	Pavel Machek <pavel@....cz>
To:	Manfred Hollstein <mhollstein@...nline.de>, joeyli <jlee@...e.com>,
	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org, linux-efi@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-crypto@...r.kernel.org,
	opensuse-kernel@...nsuse.org, David Howells <dhowells@...hat.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Len Brown <len.brown@...el.com>,
	Josh Boyer <jwboyer@...hat.com>,
	Vojtech Pavlik <vojtech@...e.cz>,
	Matt Fleming <matt.fleming@...el.com>,
	James Bottomley <james.bottomley@...senpartnership.com>,
	Greg KH <gregkh@...uxfoundation.org>, JKosina@...e.com,
	Rusty Russell <rusty@...tcorp.com.au>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>,
	"H. Peter Anvin" <hpa@...or.com>, Michal Marek <mmarek@...e.cz>,
	Gary Lin <GLin@...e.com>, Vivek Goyal <vgoyal@...hat.com>,
	Takashi Iwai <tiwai@...e.de>
Subject: Re: [PATCH 11/18] Hibernate: introduced RSA key-pair to verify
 signature of snapshot

On Tue 2013-08-27 14:01:42, Manfred Hollstein wrote:
> On Tue, 27 Aug 2013, 13:29:43 +0200, Pavel Machek wrote:
> > > > > @@ -1205,6 +1290,10 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table,
> > > > >  
> > > > >  	setup_efi_pci(boot_params);
> > > > >  
> > > > > +#ifdef CONFIG_SNAPSHOT_VERIFICATION
> > > > > +	setup_s4_keys(boot_params);
> > > > > +#endif
> > > > > +
> > > > 
> > > > Move ifdef inside the function?
> > > 
> > > OK, I will define a dummy function for non-verification situation.
> > 
> > IIRC you can just put the #ifdef inside the function body. 
> 
> This is certainly not to be invoked on a frequent basis (and therefore
> not on a hot path), but from a more general angle, wouldn't this leave
> a(nother) plain "jsr... rts" sequence without any effect other than
> burning a few cycles? If the whole function call can be disabled
> (ignored) in a certain configuration, it shouldn't call at all, should
> it?

gcc should be able to deal with optimizing that out.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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