Date: Sun, 18 Aug 2002 21:01:03 +0100 From: Ian Dowse <iedowse@maths.tcd.ie> To: Bruce Evans <bde@zeta.org.au> Cc: arch@FreeBSD.ORG Subject: Re: Solving the stack gap issue Message-ID: <200208182101.aa62911@salmon.maths.tcd.ie> In-Reply-To: Your message of "Mon, 19 Aug 2002 05:31:54 %2B1000." <20020819045750.C16172-100000@gamplex.bde.org>
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In message <20020819045750.C16172-100000@gamplex.bde.org>, Bruce Evans writes: > >The discussion was in response to axeing an undead version of >trap_pfault(). This version was intended to be used to drop support >for direct accesses. Thanks, yes, I remember now. Of course the detection of kernel accesses to user memory in trap_pfault will only trigger on unmapped addresses. To be useful for detecting this kernel code we would ideally want a way of catching all accesses, even if turning on that detection had a big performance penalty. >Even copying in pathnames is not such a good idea then. The copying >would have to be done in several compat opens, not to mention in all >other syscalls that take pathnames, instead of only in namei(). The compat modules generally want to munge paths by prepending /compat/linux for example, so all syscalls that take path arguments need to accept a kernel-space string (unless we move the path munging into namei). It is very easy to handle paths in the sys_*() functions anyway, as the uio_seg argument can be passed straight into NDINIT(). Ian To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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