From owner-cvs-src@FreeBSD.ORG Tue Apr 12 00:20:41 2005 Return-Path: Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 78C4E16A4CF for ; Tue, 12 Apr 2005 00:20:41 +0000 (GMT) Received: from mail22.sea5.speakeasy.net (mail22.sea5.speakeasy.net [69.17.117.24]) by mx1.FreeBSD.org (Postfix) with ESMTP id 8649243D62 for ; Tue, 12 Apr 2005 00:20:40 +0000 (GMT) (envelope-from jhb@FreeBSD.org) Received: (qmail 3690 invoked from network); 12 Apr 2005 00:20:40 -0000 Received: from server.baldwin.cx ([216.27.160.63]) (envelope-sender )AES256-SHA encrypted SMTP for ; 12 Apr 2005 00:20:39 -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 j3C0KXGs016395; Mon, 11 Apr 2005 20:20:34 -0400 (EDT) (envelope-from jhb@FreeBSD.org) From: John Baldwin To: Julian Elischer Date: Mon, 11 Apr 2005 18:47:07 -0400 User-Agent: KMail/1.8 References: <200504110202.j3B22Z5k014387@repoman.freebsd.org> <425AC7C9.8050801@elischer.org> In-Reply-To: <425AC7C9.8050801@elischer.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200504111847.09117.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: 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/sys/modules/ndis Makefile src/sys/dev/if_ndis if_ndis.c X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 12 Apr 2005 00:20:41 -0000 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. -- John Baldwin <>< http://www.FreeBSD.org/~jhb/ "Power Users Use the Power to Serve" = http://www.FreeBSD.org