Date: Tue, 25 Sep 2001 11:18:59 +0200 From: Bernd Walter <ticso@mail.cicely.de> To: Peter Wullinger <RivaW@gmx.de> Cc: Bernd Walter <ticso@mail.cicely.de>, freebsd-hackers@FreeBSD.ORG Subject: Re: VM Corruption - stumped, anyone have any ideas? Message-ID: <20010925111858.C27615@cicely20.cicely.de> In-Reply-To: <20010925100103.A4016@pc04.ipc-kallmuenz.de>; from RivaW@gmx.de on Tue, Sep 25, 2001 at 10:01:03AM %2B0200 References: <200109250027.f8P0RRk97980@earth.backplane.com> <200109250114.VAA20993@glatton.cnchost.com> <20010925095607.B27615@cicely20.cicely.de> <20010925100103.A4016@pc04.ipc-kallmuenz.de>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tue, Sep 25, 2001 at 10:01:03AM +0200, Peter Wullinger wrote: > On Tue, Sep 25, 2001 at 09:56:07AM +0200, Bernd Walter wrote: > > On Mon, Sep 24, 2001 at 06:14:34PM -0700, Bakul Shah wrote: > > > FWIW, in a Unix port we did I remember putting the user > > > struct *above* the kernel stack. The stack grew down so you > > > hit the red zone (the guard pages) without clobbering the > > > user struct. Since struct user _ended_ on a page boundary, > > > its size was needed at locore.s assembly time but that was a > > > small price to pay for the added safety. > > > > I don't think a guard page can help here, because the page fault > > handler needs a working stack. > > > Depends on what is does ... if it just panics and syncs and does > not care overwriting the user struct of the current process (which > is lost anyway), is this much of a problem? Please correct me if I'm missing something. If it is overwriting there is no page fault thus no guard page and no panic. If you would have a page fault there is no space where the CPU can write the state information to for entering the handler. -- B.Walter COSMO-Project http://www.cosmo-project.de ticso@cicely.de Usergroup info@cosmo-project.de To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20010925111858.C27615>