Date: Mon, 8 Mar 2010 08:54:40 -0500 From: Andrew Duane <aduane@juniper.net> To: Patrick Lamaiziere <patfbsd@davenulle.org>, "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: RE: Dead store elimination in the kernel? Message-ID: <AC6674AB7BC78549BB231821ABF7A9AE9037B67A37@EMBX01-WF.jnpr.net> In-Reply-To: <20100307232146.6b57f610@davenulle.org> References: <20100307232146.6b57f610@davenulle.org>
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owner-freebsd-hackers@freebsd.org wrote: > Hello, >=20 > I'm asking if FreeBSD is safe regarding dead store elimination made > by gcc?=20 >=20 > By example, in crypto drivers, sensitive datas are cleared by a > bzero() after use to avoid potential leakages. But the bzero() by > itself is useless, is it removed by gcc? >=20 > Thanks, regards. > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to > "freebsd-hackers-unsubscribe@freebsd.org" I would think the "correct" way to handle this is to make sure all appropri= ate items are declared volatile. This would eliminate dead store eliminatio= n, as the compiler can tell they are not dead. Unfortunately, the history of drivers (or any code) correctly using volatil= e declarations is intermittent at best. /Andrew
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