From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3yLMX3680ZzDqY9 for ; Tue, 24 Oct 2017 03:37:55 +1100 (AEDT) Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v9NGbP2j020301 for ; Mon, 23 Oct 2017 12:37:53 -0400 Received: from e06smtp11.uk.ibm.com (e06smtp11.uk.ibm.com [195.75.94.107]) by mx0a-001b2d01.pphosted.com with ESMTP id 2dsjy2ud7c-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 23 Oct 2017 12:37:52 -0400 Received: from localhost by e06smtp11.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 23 Oct 2017 17:37:50 +0100 From: "Naveen N. Rao" To: Michael Ellerman Cc: linuxppc-dev@lists.ozlabs.org, Masami Hiramatsu , Ananth N Mavinakayanahalli Subject: [PATCH 1/4] powerpc/kprobes: Disable preemption before invoking probe handler for optprobes Date: Mon, 23 Oct 2017 22:07:38 +0530 Message-Id: <2a4b854c7fc11db576e3b7ff6dcfda94c64d2842.1508776485.git.naveen.n.rao@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Per Documentation/kprobes.txt, probe handlers need to be invoked with preemption disabled. Update optimized_callback() to do so. Also move get_kprobe_ctlblk() invocation post preemption disable, since it accesses pre-cpu data. This was not an issue so far since optprobes wasn't selected if CONFIG_PREEMPT was enabled. Commit a30b85df7d599f ("kprobes: Use synchronize_rcu_tasks() for optprobe with CONFIG_PREEMPT=y") changes this. Signed-off-by: Naveen N. Rao --- arch/powerpc/kernel/optprobes.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/optprobes.c b/arch/powerpc/kernel/optprobes.c index 91e037ab20a1..60ba7f1370a8 100644 --- a/arch/powerpc/kernel/optprobes.c +++ b/arch/powerpc/kernel/optprobes.c @@ -115,7 +115,6 @@ static unsigned long can_optimize(struct kprobe *p) static void optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs) { - struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); unsigned long flags; /* This is possible if op is under delayed unoptimizing */ @@ -124,13 +123,14 @@ static void optimized_callback(struct optimized_kprobe *op, local_irq_save(flags); hard_irq_disable(); + preempt_disable(); if (kprobe_running()) { kprobes_inc_nmissed_count(&op->kp); } else { __this_cpu_write(current_kprobe, &op->kp); regs->nip = (unsigned long)op->kp.addr; - kcb->kprobe_status = KPROBE_HIT_ACTIVE; + get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; opt_pre_handler(&op->kp, regs); __this_cpu_write(current_kprobe, NULL); } @@ -140,6 +140,7 @@ static void optimized_callback(struct optimized_kprobe *op, * local_irq_restore() will re-enable interrupts, * if they were hard disabled. */ + preempt_enable_no_resched(); local_irq_restore(flags); } NOKPROBE_SYMBOL(optimized_callback); -- 2.14.2