Date: Wed, 15 Jun 2011 18:58:55 -0600 From: Scott Long <scottl@samsco.org> To: Julian Elischer <julian@FreeBSD.org> Cc: Luigi Rizzo <rizzo@iet.unipi.it>, "K. Macy" <kmacy@FreeBSD.org>, current@FreeBSD.org Subject: Re: fast/syscall-free gettimeofday ? Message-ID: <FA098515-E1C8-4514-81BA-C361DE248D84@samsco.org> In-Reply-To: <4DF951E3.7010209@freebsd.org> References: <20110614161105.GA17306@onelab2.iet.unipi.it> <BANLkTinOq73nGQT88NByuOgH3ByuA=ZLJA@mail.gmail.com> <4A46AC77-BEE5-4401-8896-4E4F1A5304B0@samsco.org> <4DF951E3.7010209@freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Jun 15, 2011, at 6:44 PM, Julian Elischer wrote: >> If this was to be extended with cached global syscall information = like gettimeofday, would we want that to be in a separate page that is = marked non-executable? Is there any way to trick the kernel into = leaking arbitrary (and thus executable) code? Also, would it matter for = jails? Per-process info like getpid would obviously have to be a = separate per-process page. >>=20 >> Scott >>=20 > In the talk about this sort of topic I have seen mention at various = times > of a page per system, a page per jail, a page per process and a page = per thread. >=20 > I'm not saying we want this all just that I've seen it mentionned.. >=20 > The per-thread one is the most intersting to do challenge wise. I guess that per-thread would be done via a pointer off of the TLS data, = or would it be yet another bumping of the stack? It would be = interesting to see how expensive it is to go that direction. Scott
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?FA098515-E1C8-4514-81BA-C361DE248D84>