From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753266AbdKVWkG (ORCPT ); Wed, 22 Nov 2017 17:40:06 -0500 Received: from omzsmtpe03.verizonbusiness.com ([199.249.25.208]:3676 "EHLO omzsmtpe03.verizonbusiness.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753153AbdKVW2M (ORCPT ); Wed, 22 Nov 2017 17:28:12 -0500 From: alexander.levin@verizon.com Cc: Masami Hiramatsu , Alexei Starovoitov , Alexei Starovoitov , Ananth N Mavinakayanahalli , Linus Torvalds , "Paul E . McKenney" , Peter Zijlstra , Steven Rostedt , Thomas Gleixner , Ingo Molnar , alexander.levin@verizon.com X-Host: pioneer.tdc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH AUTOSEL for 4.9 22/24] kprobes/x86: Disable preemption in ftrace-based jprobes Thread-Topic: [PATCH AUTOSEL for 4.9 22/24] kprobes/x86: Disable preemption in ftrace-based jprobes Thread-Index: AQHTY+DpAfoWDEf7OEuYden3pp0IXQ== Date: Wed, 22 Nov 2017 22:26:15 +0000 Message-ID: <20171122222604.20122-22-alexander.levin@verizon.com> References: <20171122222604.20122-1-alexander.levin@verizon.com> In-Reply-To: <20171122222604.20122-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id vAMMeUw7026450 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 --- arch/x86/kernel/kprobes/ftrace.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/kprobes/ftrace.c b/arch/x86/kernel/kprobes/ftrace.c index 5f8f0b3cc674..2c0b0b645a74 100644 --- 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, struct pt_regs *regs, __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 ip, unsigned long parent_ip, /* 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: -- 2.11.0