From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932166AbdBGPON (ORCPT ); Tue, 7 Feb 2017 10:14:13 -0500 Received: from mail.kernel.org ([198.145.29.136]:55720 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932116AbdBGPOM (ORCPT ); Tue, 7 Feb 2017 10:14:12 -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 2/3] kprobes/arm64: Fix a possible deadlock case in kretprobe Date: Wed, 8 Feb 2017 00:13:14 +0900 Message-Id: <148648038381.30949.1443281264586280005.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, arm64 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/arm64/kernel/probes/kprobes.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c index 2a07aae..401f7c9 100644 --- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c @@ -561,6 +561,8 @@ bool arch_within_kprobe_blacklist(unsigned long addr) return false; } +static struct kprobe dummy_retprobe = {.addr = (void *)&kretprobe_trampoline}; + void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs) { struct kretprobe_instance *ri = NULL; @@ -572,6 +574,11 @@ void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs) kprobe_opcode_t *correct_ret_addr = NULL; 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); /* @@ -614,10 +621,9 @@ void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs) orig_ret_address = (unsigned long)ri->ret_addr; if (ri->rp && ri->rp->handler) { __this_cpu_write(current_kprobe, &ri->rp->kp); - get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; ri->ret_addr = correct_ret_addr; ri->rp->handler(ri, regs); - __this_cpu_write(current_kprobe, NULL); + __this_cpu_write(current_kprobe, &dummy_retprobe); } recycle_rp_inst(ri, &empty_rp); @@ -632,6 +638,8 @@ void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs) } 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);