From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754173Ab1EaM1d (ORCPT ); Tue, 31 May 2011 08:27:33 -0400 Received: from mail-pv0-f174.google.com ([74.125.83.174]:43952 "EHLO mail-pv0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751662Ab1EaM1c convert rfc822-to-8bit (ORCPT ); Tue, 31 May 2011 08:27:32 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:from:date :x-google-sender-auth:message-id:subject:to:cc:content-type :content-transfer-encoding; b=uoPu+YZagUX3bgJloXK8pNaMDfrbZnL+aP4fPQqz+rAhhLbIN4vzbrewxiW5b6yTri bDr2VyUUMMyNbVhxC9dHUA95rNYv5AoDDe8XpatEXGVrv8uKaF+fEr+ahGFfJ3c2I2At OzNRlOszv/JYeXvloN6A8EuorM5OopGGyQK0o= MIME-Version: 1.0 In-Reply-To: <20110531080758.GA24172@elte.hu> References: <20110529191924.GD9835@elte.hu> <20110531080758.GA24172@elte.hu> From: Andrew Lutomirski Date: Tue, 31 May 2011 08:27:12 -0400 X-Google-Sender-Auth: 5r0h-UntqT0uXeS4NF-p295ZA5k Message-ID: Subject: Re: [PATCH 0/5] x86-64: Remove syscall instructions at fixed addresses To: Ingo Molnar Cc: Thomas Gleixner , x86@kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds , Andrew Morton , Arjan van de Ven , Jan Beulich Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 31, 2011 at 4:07 AM, Ingo Molnar wrote: > > * Andrew Lutomirski wrote: > >> On Sun, May 29, 2011 at 3:19 PM, Ingo Molnar wrote: >> > Btw., do you know CONFIG_X86_PTDUMP=y and /debug/kernel_page_tables? >> > You could use that to double check that after your patches all >> > executable (and fixed address) pages are removed [or are harmless]. >> >> Done.  Now there's only one user-executable page and it's mostly harmless. > > ok. Will test your v3 series. > >> Maybe I'll try to get rid of vread_tsc and vread_hpet later on to >> make it even more harmless. > > Yeah, that's a good idea. They need pushing into the INT 0xCC > do_intcc() handler, that's all that's needed AFAICS - or can you see > other complications with them? > They're called from the vDSO. I think they should just be moved into the vDSO since they're not used by the vsyscall code any more, but there are two problems. The clocksource.vread mechanism (or whatever its called) won't really work if we let them get relocated (not a big deal). More importantly, vread_tsc contains an alternative and the vDSO can't currently contain alternative instructions. That can probably be fixed, but it'll take a bit of work. --Andy