From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B9AB4C47404 for ; Fri, 11 Oct 2019 11:09:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8FEE3206CD for ; Fri, 11 Oct 2019 11:09:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="fIqW+zhp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727865AbfJKLJh (ORCPT ); Fri, 11 Oct 2019 07:09:37 -0400 Received: from merlin.infradead.org ([205.233.59.134]:41834 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727226AbfJKLJh (ORCPT ); Fri, 11 Oct 2019 07:09:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=hd7DeC8X5msMUThPgUPk7q3GKjl3k7DCzGsETcIzACA=; b=fIqW+zhpMmwxyXiudCtqbZKiv Rua75ufe08S0TzPUEwj66GcMdVNwwXbpRvk/iuPTQFxNLhZfz9f/bcY7LcVq1L/D371z5dZ5KrrEB oc3/AjbaMA2CBmd5sSo2S/ZVR2gHpFAPNvWN3fh6LhzM619VRjxxMdHaohZv+P+MUPzNyuBpEGXNf EtQIKhx10aE9evxbyVJUpnod+Mej41MZaXZSPfZdsdffT4XspS1ArVx2SpMc3SdV4mpZat1evXRc8 BR5kPNhKGk3QyzdMI3aKXY1Hb8NJUzlavX+ANPjzLdc7zzIhQXA5VjNKkzlMm0Z5u2RM9yLdwSGC4 vw5Mfg1XQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iIsne-0006qb-Ky; Fri, 11 Oct 2019 11:09:35 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 9B9193013A4; Fri, 11 Oct 2019 13:08:40 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 115BE20230369; Fri, 11 Oct 2019 13:09:33 +0200 (CEST) Date: Fri, 11 Oct 2019 13:09:33 +0200 From: Peter Zijlstra To: Steven Rostedt Cc: LKML , Jessica Yu , Ingo Molnar Subject: Re: [PATCH] ftrace/module: Allow ftrace to make only loaded module text read-write Message-ID: <20191011110933.GX2328@hirez.programming.kicks-ass.net> References: <20191009223638.60b78727@oasis.local.home> <20191010073121.GN2311@hirez.programming.kicks-ass.net> <20191010093329.GI2359@hirez.programming.kicks-ass.net> <20191010093650.GJ2359@hirez.programming.kicks-ass.net> <20191010122909.GK2359@hirez.programming.kicks-ass.net> <20191010105515.5eba7f31@gandalf.local.home> <20191010170111.GQ2328@hirez.programming.kicks-ass.net> <20191010132013.7f3388bc@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191010132013.7f3388bc@gandalf.local.home> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 10, 2019 at 01:20:13PM -0400, Steven Rostedt wrote: > Hmm, I'm lost at what the below is trying to do with respect to the > above. The below is an alternative approach for the module load issue. It accepts we patch 'late' and then uses text_poke_bp(). It works. We can then look at moving all that patching to ftrace_module_init() later when we figure out how to do it across architectures. > > --- a/arch/x86/kernel/ftrace.c > > +++ b/arch/x86/kernel/ftrace.c > > @@ -34,6 +34,8 @@ > > > > #ifdef CONFIG_DYNAMIC_FTRACE > > > > +static int ftrace_poke_late = 0; > > + > > int ftrace_arch_code_modify_prepare(void) > > __acquires(&text_mutex) > > { > > @@ -43,12 +45,15 @@ int ftrace_arch_code_modify_prepare(void > > * ftrace has it set to "read/write". > > */ > > mutex_lock(&text_mutex); > > + ftrace_poke_late = 1; > > return 0; > > } > > > > int ftrace_arch_code_modify_post_process(void) > > __releases(&text_mutex) > > { > > + text_poke_finish(); > > + ftrace_poke_late = 0; > > mutex_unlock(&text_mutex); > > return 0; > > } > > @@ -116,7 +121,10 @@ ftrace_modify_code_direct(unsigned long > > return ret; > > > > /* replace the text with the new text */ > > - text_poke_early((void *)ip, new_code, MCOUNT_INSN_SIZE); > > + if (ftrace_poke_late) > > + text_poke_queue((void *)ip, new_code, MCOUNT_INSN_SIZE, NULL); > > + else > > + text_poke_early((void *)ip, new_code, MCOUNT_INSN_SIZE); > > return 0; > > } > > >