Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756126Ab0A0Vrz (ORCPT ); Wed, 27 Jan 2010 16:47:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756073Ab0A0Vry (ORCPT ); Wed, 27 Jan 2010 16:47:54 -0500 Received: from mx1.redhat.com ([209.132.183.28]:36005 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755837Ab0A0Vrx (ORCPT ); Wed, 27 Jan 2010 16:47:53 -0500 From: Masami Hiramatsu Subject: [PATCH tracing/kprobes] kprobes: Disable booster when CONFIG_PREEMPT=y To: Ingo Molnar , lkml Cc: systemtap , DLE , Masami Hiramatsu , Ananth N Mavinakayanahalli , Frederic Weisbecker , Ingo Molnar , Jim Keniston , Mathieu Desnoyers , Steven Rostedt Date: Wed, 27 Jan 2010 16:55:31 -0500 Message-ID: <20100127215531.24775.26807.stgit@dhcp-100-2-132.bos.redhat.com> In-Reply-To: <4B5E476C.9030303@redhat.com> References: <4B5E476C.9030303@redhat.com> User-Agent: StGIT/0.14.3 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3615 Lines: 109 Disable kprobe booster when CONFIG_PREEMPT=y, because it can't ensure that all kernel threads preempted on kprobe's boosted slot run out from the slot even using freeze_processes(). The booster on preemptive kernel will be resumed if synchronize_tasks() or something like that is introduced. Signed-off-by: Masami Hiramatsu Cc: Ananth N Mavinakayanahalli Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Jim Keniston CC: Mathieu Desnoyers Cc: Steven Rostedt --- arch/ia64/kernel/kprobes.c | 2 +- arch/x86/kernel/kprobes.c | 2 +- kernel/kprobes.c | 29 ++--------------------------- 3 files changed, 4 insertions(+), 29 deletions(-) diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c index 9adac44..7026b29 100644 --- a/arch/ia64/kernel/kprobes.c +++ b/arch/ia64/kernel/kprobes.c @@ -870,7 +870,7 @@ static int __kprobes pre_kprobes_handler(struct die_args *args) return 1; ss_probe: -#if !defined(CONFIG_PREEMPT) || defined(CONFIG_FREEZER) +#if !defined(CONFIG_PREEMPT) if (p->ainsn.inst_flag == INST_FLAG_BOOSTABLE && !p->post_handler) { /* Boost up -- we can execute copied instructions directly */ ia64_psr(regs)->ri = p->ainsn.slot; diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c index 5b8c750..9453815 100644 --- a/arch/x86/kernel/kprobes.c +++ b/arch/x86/kernel/kprobes.c @@ -429,7 +429,7 @@ void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri, static void __kprobes setup_singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) { -#if !defined(CONFIG_PREEMPT) || defined(CONFIG_FREEZER) +#if !defined(CONFIG_PREEMPT) if (p->ainsn.boostable == 1 && !p->post_handler) { /* Boost up -- we can execute copied instructions directly */ reset_current_kprobe(); diff --git a/kernel/kprobes.c b/kernel/kprobes.c index b7df302..9907a03 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -124,30 +124,6 @@ static LIST_HEAD(kprobe_insn_pages); static int kprobe_garbage_slots; static int collect_garbage_slots(void); -static int __kprobes check_safety(void) -{ - int ret = 0; -#if defined(CONFIG_PREEMPT) && defined(CONFIG_FREEZER) - ret = freeze_processes(); - if (ret == 0) { - struct task_struct *p, *q; - do_each_thread(p, q) { - if (p != current && p->state == TASK_RUNNING && - p->pid != 0) { - printk("Check failed: %s is running\n",p->comm); - ret = -1; - goto loop_end; - } - } while_each_thread(p, q); - } -loop_end: - thaw_processes(); -#else - synchronize_sched(); -#endif - return ret; -} - /** * __get_insn_slot() - Find a slot on an executable page for an instruction. * We allocate an executable page if there's no room on existing ones. @@ -235,9 +211,8 @@ static int __kprobes collect_garbage_slots(void) { struct kprobe_insn_page *kip, *next; - /* Ensure no-one is preepmted on the garbages */ - if (check_safety()) - return -EAGAIN; + /* Ensure no-one is interrupted on the garbages */ + synchronize_sched(); list_for_each_entry_safe(kip, next, &kprobe_insn_pages, list) { int i; -- Masami Hiramatsu Software Engineer Hitachi Computer Products (America), Inc. Software Solutions Division e-mail: mhiramat@redhat.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/