Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752245AbaGKC0n (ORCPT ); Thu, 10 Jul 2014 22:26:43 -0400 Received: from mail9.hitachi.co.jp ([133.145.228.44]:54832 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751409AbaGKC0m (ORCPT ); Thu, 10 Jul 2014 22:26:42 -0400 Message-ID: <53BF4B5A.3000302@hitachi.com> Date: Fri, 11 Jul 2014 11:26:34 +0900 From: Masami Hiramatsu Organization: Hitachi, Ltd., Japan User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Jiri Kosina Cc: Josh Poimboeuf , Steven Rostedt , linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Thomas Gleixner , "Paul E. McKenney" , Namhyung Kim , "H. Peter Anvin" , Oleg Nesterov , Seth Jennings , Jiri Slaby Subject: Re: [RFC][PATCH 0/3] ftrace: Add dynamically allocated trampolines References: <20140703200750.648550267@goodmis.org> <20140710213620.GA19858@treble.redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (2014/07/11 6:44), Jiri Kosina wrote: > On Thu, 10 Jul 2014, Josh Poimboeuf wrote: > >> I did some testing with kpatch and I found one minor issue. The dynamically >> allocated trampoline seems to confuse dump_stack() somewhat. >> >> I added a dump_stack() call in my ftrace_ops callback function >> (kpatch_ftrace_handler) which had a filter on meminfo_proc_show(). > > Interesting. Are you using dwarf2 unwinder for stack dumping by any > chance? It seems to get things right here. Will look into it more > tomorrow. Hmm, can dwarf2 unwinder work on the trampoline method? Since the trampoline just a copy of instructions which will not have CFI(which is stored in dwarf section), I guess it may not work... Frame pointer (push bp and save sp to bp on the entry) can work anyway. Thank you, -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com -- 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/