Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755953Ab3GKKyO (ORCPT ); Thu, 11 Jul 2013 06:54:14 -0400 Received: from cantor2.suse.de ([195.135.220.15]:40092 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755913Ab3GKKyM (ORCPT ); Thu, 11 Jul 2013 06:54:12 -0400 Date: Thu, 11 Jul 2013 12:54:08 +0200 (CEST) From: Jiri Kosina To: "H. Peter Anvin" Cc: Masami Hiramatsu , Steven Rostedt , Jason Baron , Borislav Petkov , linux-kernel@vger.kernel.org Subject: Re: [RFC] [PATCH 1/2 v2] x86: introduce int3-based instruction patching In-Reply-To: Message-ID: References: <51DDD3E9.6090601@linux.intel.com> User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1121 Lines: 29 On Thu, 11 Jul 2013, Jiri Kosina wrote: > > Returning to the instruction will, in effect, be a busy-wait for the > > faulted CPU until the patch is complete; more or less what stop_machine > > would do, but only for a CPU which actually strays into the affected > > region. > > To be honest, I fail to see a clear advantage ... we don't avoid any extra > IPI by it, and wrt. "correctness", the end result is the same. Ok, after some offline discussion, my understanding is that with this proposal you are willing to make this usable in a more general way than just simple nop -> jump -> nop patching. That makes sense, but I'd propose to have a different independent interface for this if needed (text_poke_bp_busy() ... ?) in parallel to the text_poke_bp() as is in my patchset, due to the obvious extra cycles it's bringing. Thanks, -- Jiri Kosina SUSE Labs -- 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/