Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757328Ab3GLH6A (ORCPT ); Fri, 12 Jul 2013 03:58:00 -0400 Received: from mail.skyhub.de ([78.46.96.112]:59316 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757273Ab3GLH56 (ORCPT ); Fri, 12 Jul 2013 03:57:58 -0400 Date: Fri, 12 Jul 2013 09:57:38 +0200 From: Borislav Petkov To: "H. Peter Anvin" Cc: Jiri Kosina , Masami Hiramatsu , Steven Rostedt , Jason Baron , Joe Perches , linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2 v3] x86: introduce int3-based instruction patching Message-ID: <20130712075738.GB24008@pd.tnic> References: <51DF1B3C.8040603@linux.intel.com> <20130711210452.GE8900@pd.tnic> <51DF2566.8000806@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <51DF2566.8000806@linux.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1213 Lines: 39 On Thu, Jul 11, 2013 at 02:36:38PM -0700, H. Peter Anvin wrote: > On 07/11/2013 02:04 PM, Borislav Petkov wrote: > > On Thu, Jul 11, 2013 at 01:53:16PM -0700, H. Peter Anvin wrote: > >> Has anyone talked to AMD or VIA about this at all? > > > > I guess I can try to take care of the AMD part. Just to confirm, is this > > the exact sequence we're interested in: > > > > 1. Setup int3 handler for fixup. > > > > 2. Put a breakpoint (int3) on the first byte of modifying region, and > > synchronize code on all CPUs. > > > > 3. Modify other bytes of modifying region. > > > > 4. Modify the first byte of modifying region, and synchronize code on > > all CPUs. > > > > 5. Clear int3 handler. > > > > If a suitable int3 handler is left permanently in place then the > > synchronization in step 4 is unnecessary. > > > > Correct. Right, above sequence would work on AMD. -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/