From owner-cvs-all@FreeBSD.ORG Tue Apr 12 01:08:44 2005 Return-Path: Delivered-To: cvs-all@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 8BC8016A4D2 for ; Tue, 12 Apr 2005 01:08:44 +0000 (GMT) Received: from mail27.sea5.speakeasy.net (mail27.sea5.speakeasy.net [69.17.117.29]) by mx1.FreeBSD.org (Postfix) with ESMTP id 5804043D4C for ; Tue, 12 Apr 2005 01:08:43 +0000 (GMT) (envelope-from jhb@FreeBSD.org) Received: (qmail 16767 invoked from network); 12 Apr 2005 01:08:43 -0000 Received: from server.baldwin.cx ([216.27.160.63]) (envelope-sender )AES256-SHA encrypted SMTP for ; 12 Apr 2005 01:08:39 -0000 Received: from [131.106.57.68] (p178.n-lapop01.stsn.com [12.129.240.178]) (authenticated bits=0) by server.baldwin.cx (8.13.1/8.13.1) with ESMTP id j3C17mbq016686; Mon, 11 Apr 2005 21:08:21 -0400 (EDT) (envelope-from jhb@FreeBSD.org) From: John Baldwin To: Jeff Roberson Date: Mon, 11 Apr 2005 21:00:44 -0400 User-Agent: KMail/1.8 References: <200504110202.j3B22Z5k014387@repoman.freebsd.org> <200504111847.09117.jhb@FreeBSD.org> <20050411205510.B28571@mail.chesapeake.net> In-Reply-To: <20050411205510.B28571@mail.chesapeake.net> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200504112100.46518.jhb@FreeBSD.org> X-Spam-Status: No, score=-2.2 required=4.2 tests=ALL_TRUSTED,SUBJ_HAS_SPACES autolearn=failed version=3.0.2 X-Spam-Checker-Version: SpamAssassin 3.0.2 (2004-11-16) on server.baldwin.cx cc: Bill Paul cc: src-committers@FreeBSD.org cc: Julian Elischer cc: cvs-all@FreeBSD.org cc: cvs-src@FreeBSD.org Subject: Re: cvs commit: src/sys/compat/ndis hal_var.h kern_ndis.c kern_windrv.c ndis_var.h ntoskrnl_var.h pe_var.h subr_hal.c subr_ndis.c subr_ntoskrnl.c subr_usbd.c winx32_wrap.S src/s X-BeenThere: cvs-all@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the entire tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 12 Apr 2005 01:08:44 -0000 On Monday 11 April 2005 08:55 pm, Jeff Roberson wrote: > On Mon, 11 Apr 2005, John Baldwin wrote: > > On Monday 11 April 2005 02:54 pm, Julian Elischer wrote: > > > Bill Paul wrote: > > > >wpaul 2005-04-11 02:02:35 UTC > > > > > > > > > > > > The twist has to do with the fact that Microsoft supports structured > > > > exception handling in kernel mode. On the i386 arch, exception > > > > handling is implemented by hanging an exception registration list off > > > > the Thread Environment Block (TEB), and the TEB is accessed via the > > > > %fs register. The problem is, we use %fs as a pointer to the pcpu > > > > stucture, which means any driver that tries to write through %fs:0 > > > > will overwrite the curthread pointer and make a serious mess of > > > > things. > > > > > > > > To get around this, Project Evil now creates a special entry in > > > > the GDT on each processor. When we call into Windows code, a context > > > > switch routine will fix up %fs so it points to our new descriptor, > > > > which in turn points to a fake TEB. When the Windows code returns, > > > > or calls out to an external routine, we swap %fs back again. > > > > Currently, Project Evil makes use of GDT slot 7, which is all 0s by > > > > default. I fully expect someone to jump up and say I can't do that, > > > > but I couldn't find any code that makes use of this entry anywhere. > > > > Sadly, this was the only method I could come up with that worked on > > > > both UP and SMP. (Modifying the LDT works on UP, but becomes > > > > incredibly complicated on SMP.) If necessary, the context switching > > > > stuff can be yanked out while preserving the convention calling > > > > wrappers. > > > > > > Maybe we could emulate $soft and use %fs as a thread pointer instead > > > and have pcpu > > > pointed to via that :-) > > > > I think NDIS drivers want %fs to point to a Windows-specific structure > > rather than a 'struct thread' so I don't think that would buy us anything > > except for even more memory indirects when we do a pcpu lookup. > > Isn't curthread a much more frequent fetch than PCPU anything? It might > actually be a win. Fetching curthread is already a single op: mv %fs:0x4, %eax (or whatever offset it is). Unless you wanted to map all thread members of curthread which would result in lots of ugly code (use cuthread_get(foo) instead of curthread->td_foo to use it) plus problems with getting an actual real KVA for curthread you wouldn't get any better. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org