From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:39186 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752059AbdLFQbf (ORCPT ); Wed, 6 Dec 2017 11:31:35 -0500 Subject: Patch "kprobes/x86: Disable preemption in ftrace-based jprobes" has been added to the 4.4-stable tree To: mhiramat@kernel.org, alexander.levin@verizon.com, ananth@linux.vnet.ibm.com, ast@fb.com, ast@kernel.org, gregkh@linuxfoundation.org, mingo@kernel.org, paulmck@linux.vnet.ibm.com, peterz@infradead.org, rostedt@goodmis.org, tglx@linutronix.de, torvalds@linux-foundation.org Cc: , From: Date: Wed, 06 Dec 2017 17:31:29 +0100 Message-ID: <1512577889175191@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled kprobes/x86: Disable preemption in ftrace-based jprobes to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kprobes-x86-disable-preemption-in-ftrace-based-jprobes.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From foo@baz Wed Dec 6 16:43:17 CET 2017 From: Masami Hiramatsu Date: Tue, 19 Sep 2017 19:01:40 +0900 Subject: kprobes/x86: Disable preemption in ftrace-based jprobes From: Masami Hiramatsu [ Upstream commit 5bb4fc2d8641219732eb2bb654206775a4219aca ] Disable preemption in ftrace-based jprobe handlers as described in Documentation/kprobes.txt: "Probe handlers are run with preemption disabled." This will fix jprobes behavior when CONFIG_PREEMPT=y. Signed-off-by: Masami Hiramatsu Cc: Alexei Starovoitov Cc: Alexei Starovoitov Cc: Ananth N Mavinakayanahalli Cc: Linus Torvalds Cc: Paul E . McKenney Cc: Peter Zijlstra Cc: Steven Rostedt Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/150581530024.32348.9863783558598926771.stgit@devbox Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/kprobes/ftrace.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) --- a/arch/x86/kernel/kprobes/ftrace.c +++ b/arch/x86/kernel/kprobes/ftrace.c @@ -26,7 +26,7 @@ #include "common.h" static nokprobe_inline -int __skip_singlestep(struct kprobe *p, struct pt_regs *regs, +void __skip_singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb, unsigned long orig_ip) { /* @@ -41,20 +41,21 @@ int __skip_singlestep(struct kprobe *p, __this_cpu_write(current_kprobe, NULL); if (orig_ip) regs->ip = orig_ip; - return 1; } int skip_singlestep(struct kprobe *p, struct pt_regs *regs, struct kprobe_ctlblk *kcb) { - if (kprobe_ftrace(p)) - return __skip_singlestep(p, regs, kcb, 0); - else - return 0; + if (kprobe_ftrace(p)) { + __skip_singlestep(p, regs, kcb, 0); + preempt_enable_no_resched(); + return 1; + } + return 0; } NOKPROBE_SYMBOL(skip_singlestep); -/* Ftrace callback handler for kprobes */ +/* Ftrace callback handler for kprobes -- called under preepmt disabed */ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, struct ftrace_ops *ops, struct pt_regs *regs) { @@ -77,13 +78,17 @@ void kprobe_ftrace_handler(unsigned long /* Kprobe handler expects regs->ip = ip + 1 as breakpoint hit */ regs->ip = ip + sizeof(kprobe_opcode_t); + /* To emulate trap based kprobes, preempt_disable here */ + preempt_disable(); __this_cpu_write(current_kprobe, p); kcb->kprobe_status = KPROBE_HIT_ACTIVE; - if (!p->pre_handler || !p->pre_handler(p, regs)) + if (!p->pre_handler || !p->pre_handler(p, regs)) { __skip_singlestep(p, regs, kcb, orig_ip); + preempt_enable_no_resched(); + } /* * If pre_handler returns !0, it sets regs->ip and - * resets current kprobe. + * resets current kprobe, and keep preempt count +1. */ } end: Patches currently in stable-queue which might be from mhiramat@kernel.org are queue-4.4/kprobes-x86-disable-preemption-in-ftrace-based-jprobes.patch