From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754718AbdBGPPZ (ORCPT ); Tue, 7 Feb 2017 10:15:25 -0500 Received: from mail.kernel.org ([198.145.29.136]:55944 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754016AbdBGPPW (ORCPT ); Tue, 7 Feb 2017 10:15:22 -0500 From: Masami Hiramatsu To: Ingo Molnar Cc: Masami Hiramatsu , linux-kernel@vger.kernel.org, Peter Zijlstra , Ananth N Mavinakayanahalli , Thomas Gleixner , "H . Peter Anvin" , Jon Medhurst , Wang Nan , Russell King , Catalin Marinas , Will Deacon , "David A . Long" , Sandeepa Prabhu Subject: [BUGFIX PATCH tip/master 3/3] kprobes/arm: Fix a possible deadlock case in kretprobe Date: Wed, 8 Feb 2017 00:14:26 +0900 Message-Id: <148648045599.30949.7887637175201036554.stgit@devbox> X-Mailer: git-send-email 2.9.3 In-Reply-To: <148648024215.30949.11929183640906306731.stgit@devbox> References: <148648024215.30949.11929183640906306731.stgit@devbox> User-Agent: StGit/0.17.1-dirty 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 Similar to x86 kretprobe deadlock issue, arm also implements kretprobe-booster (trampoline code directly call handler.) So it has same deadlock issue if there are 2 kretprobes on normal function and the function called from FIQ (or anywhere which can be invoked when local_irq_disabled). This fixes the issue as same as we did on x86. Signed-off-by: Masami Hiramatsu --- arch/arm/probes/kprobes/core.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c index b6dc9d8..3e5aab7 100644 --- a/arch/arm/probes/kprobes/core.c +++ b/arch/arm/probes/kprobes/core.c @@ -426,6 +426,8 @@ void __naked __kprobes kretprobe_trampoline(void) : : : "memory"); } +static struct kprobe dummy_retprobe = {.addr = (void *)&kretprobe_trampoline}; + /* Called from kretprobe_trampoline */ static __used __kprobes void *trampoline_handler(struct pt_regs *regs) { @@ -436,6 +438,11 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs) unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; INIT_HLIST_HEAD(&empty_rp); + + /* This prevents kernel to change running cpu while processing */ + preempt_disable(); + get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; + __this_cpu_write(current_kprobe, &dummy_retprobe); kretprobe_hash_lock(current, &head, &flags); /* @@ -458,9 +465,8 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs) if (ri->rp && ri->rp->handler) { __this_cpu_write(current_kprobe, &ri->rp->kp); - get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; ri->rp->handler(ri, regs); - __this_cpu_write(current_kprobe, NULL); + __this_cpu_write(current_kprobe, &dummy_retprobe); } orig_ret_address = (unsigned long)ri->ret_addr; @@ -477,6 +483,8 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs) kretprobe_assert(ri, orig_ret_address, trampoline_address); kretprobe_hash_unlock(current, &flags); + __this_cpu_write(current_kprobe, NULL); + preempt_enable_no_resched(); hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { hlist_del(&ri->hlist);