Return-Path: Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192] helo=mx.sourceforge.net) by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1QvJBG-0001S8-51 for user-mode-linux-devel@lists.sourceforge.net; Mon, 22 Aug 2011 01:19:58 +0000 Received: from terminus.zytor.com ([198.137.202.10] helo=mail.zytor.com) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.76) id 1QvJBF-0003eH-9r for user-mode-linux-devel@lists.sourceforge.net; Mon, 22 Aug 2011 01:19:58 +0000 Message-ID: <4E51AEAD.8040005@zytor.com> Date: Sun, 21 Aug 2011 18:19:41 -0700 From: "H. Peter Anvin" MIME-Version: 1.0 References: <20110820011845.GC2203@ZenIV.linux.org.uk> <4E4FD12F.70508@nod.at> <20110820201406.GF2203@ZenIV.linux.org.uk> <4E501F51.9060905@nod.at> <20110821063443.GH2203@ZenIV.linux.org.uk> <20110821084230.GI2203@ZenIV.linux.org.uk> <20110821144352.GJ2203@ZenIV.linux.org.uk> <20110821164124.GL2203@ZenIV.linux.org.uk> In-Reply-To: List-Id: The user-mode Linux development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: user-mode-linux-devel-bounces@lists.sourceforge.net Subject: Re: [uml-devel] SYSCALL, ptrace and syscall restart breakages (Re: [RFC] weird crap with vdso on uml/i386) To: Linus Torvalds Cc: Andrew Lutomirski , user-mode-linux-devel@lists.sourceforge.net, Richard Weinberger , linux-kernel@vger.kernel.org, mingo@redhat.com, Al Viro On 08/21/2011 06:09 PM, Linus Torvalds wrote: > > Indeed. Just add an "int 0x80" instruction to the vsyscall thing, and > you'd be done. > > In fact, just replace the > > jmp .Lenter_kernel > > with > > int 0x80 > > and you'd be pretty much all done, no? > > (Ok, that's probably a huge over-simplification, but perhaps "close > enough" to true that it would be workable) > Hm... I think a jump to something which adjusts %esp and invokes int $0x80 might just work, but only for SYSENTER. SYSCALL is different, especially since SYSCALL is legal to execute from anywhere in userspace (and no, as we have learned already doing EIP checking is *NOT* acceptable.) -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. ------------------------------------------------------------------------------ uberSVN's rich system and user administration capabilities and model configuration take the hassle out of deploying and managing Subversion and the tools developers use with it. Learn more about uberSVN and get a free download at: http://p.sf.net/sfu/wandisco-dev2dev _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel