From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756937AbXKQPCs (ORCPT ); Sat, 17 Nov 2007 10:02:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752123AbXKQPCk (ORCPT ); Sat, 17 Nov 2007 10:02:40 -0500 Received: from tomts16-srv.bellnexxia.net ([209.226.175.4]:43300 "EHLO tomts16-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752008AbXKQPCj (ORCPT ); Sat, 17 Nov 2007 10:02:39 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Aq4HAHORPkdMROHU/2dsb2JhbACBXw Date: Sat, 17 Nov 2007 10:02:36 -0500 From: Mathieu Desnoyers To: Roel Kluin <12o3l@tiscali.nl> Cc: linux-kernel@vger.kernel.org, Ananth N Mavinakayanahalli , prasanna@in.ibm.com, anil.s.keshavamurthy@intel.com, davem@davemloft.net Subject: Re: [rfc-patch 07/11] Text Edit Lock - kprobes architecture independent support Message-ID: <20071117150236.GA16091@Krystal> References: <20071116195747.448703304@polymtl.ca> <20071116200139.134470826@polymtl.ca> <473EBFBA.7080705@tiscali.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <473EBFBA.7080705@tiscali.nl> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 10:00:31 up 13 days, 20:05, 2 users, load average: 0.81, 0.66, 0.51 User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Roel Kluin (12o3l@tiscali.nl) wrote: [...] > > for (i = 0; i < KPROBE_TABLE_SIZE; i++) { > > head = &kprobe_table[i]; > > + kernel_text_lock(); > > hlist_for_each_entry_rcu(p, node, head, hlist) > > arch_arm_kprobe(p); > > + kernel_text_unlock(); > > } > > isn't it better to put the kernel_text_lock around the for loop? > > > > > kprobe_enabled = true; > > @@ -969,10 +974,12 @@ static void __kprobes disable_all_kprobe > > printk(KERN_INFO "Kprobes globally disabled\n"); > > for (i = 0; i < KPROBE_TABLE_SIZE; i++) { > > head = &kprobe_table[i]; > > + kernel_text_lock(); > > hlist_for_each_entry_rcu(p, node, head, hlist) { > > if (!arch_trampoline_kprobe(p)) > > arch_disarm_kprobe(p); > > } > > + kernel_text_unlock(); > > } > > same question here > Yes, you are right, although it does not have to be fast. Here is the updated patch. Text Edit Lock - kprobes architecture independent support Use the mutual exclusion provided by the text edit lock in the kprobes code. It allows coherent manipulation of the kernel code by other subsystems. Changelog: Move the kernel_text_lock/unlock out of the for loops. Signed-off-by: Mathieu Desnoyers Acked-by: Ananth N Mavinakayanahalli CC: prasanna@in.ibm.com CC: ananth@in.ibm.com CC: anil.s.keshavamurthy@intel.com CC: davem@davemloft.net CC: Roel Kluin <12o3l@tiscali.nl> --- kernel/kprobes.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-) Index: linux-2.6-lttng/kernel/kprobes.c =================================================================== --- linux-2.6-lttng.orig/kernel/kprobes.c 2007-11-16 13:40:06.000000000 -0500 +++ linux-2.6-lttng/kernel/kprobes.c 2007-11-17 10:00:23.000000000 -0500 @@ -43,6 +43,7 @@ #include #include #include +#include #include #include @@ -568,9 +569,10 @@ static int __kprobes __register_kprobe(s goto out; } + kernel_text_lock(); ret = arch_prepare_kprobe(p); if (ret) - goto out; + goto out_unlock_text; INIT_HLIST_NODE(&p->hlist); hlist_add_head_rcu(&p->hlist, @@ -578,7 +580,8 @@ static int __kprobes __register_kprobe(s if (kprobe_enabled) arch_arm_kprobe(p); - +out_unlock_text: + kernel_text_unlock(); out: mutex_unlock(&kprobe_mutex); @@ -621,8 +624,11 @@ valid_p: * enabled - otherwise, the breakpoint would already have * been removed. We save on flushing icache. */ - if (kprobe_enabled) + if (kprobe_enabled) { + kernel_text_lock(); arch_disarm_kprobe(p); + kernel_text_unlock(); + } hlist_del_rcu(&old_p->hlist); cleanup_p = 1; } else { @@ -644,9 +650,7 @@ valid_p: list_del_rcu(&p->list); kfree(old_p); } - mutex_lock(&kprobe_mutex); arch_remove_kprobe(p); - mutex_unlock(&kprobe_mutex); } else { mutex_lock(&kprobe_mutex); if (p->break_handler) @@ -717,7 +721,6 @@ static int __kprobes pre_handler_kretpro ri->rp = rp; ri->task = current; arch_prepare_kretprobe(ri, regs); - /* XXX(hch): why is there no hlist_move_head? */ hlist_del(&ri->uflist); hlist_add_head(&ri->uflist, &ri->rp->used_instances); @@ -938,11 +941,13 @@ static void __kprobes enable_all_kprobes if (kprobe_enabled) goto already_enabled; + kernel_text_lock(); for (i = 0; i < KPROBE_TABLE_SIZE; i++) { head = &kprobe_table[i]; hlist_for_each_entry_rcu(p, node, head, hlist) arch_arm_kprobe(p); } + kernel_text_unlock(); kprobe_enabled = true; printk(KERN_INFO "Kprobes globally enabled\n"); @@ -967,6 +972,7 @@ static void __kprobes disable_all_kprobe kprobe_enabled = false; printk(KERN_INFO "Kprobes globally disabled\n"); + kernel_text_lock(); for (i = 0; i < KPROBE_TABLE_SIZE; i++) { head = &kprobe_table[i]; hlist_for_each_entry_rcu(p, node, head, hlist) { @@ -974,6 +980,7 @@ static void __kprobes disable_all_kprobe arch_disarm_kprobe(p); } } + kernel_text_unlock(); mutex_unlock(&kprobe_mutex); /* Allow all currently running kprobes to complete */ -- Mathieu Desnoyers Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68