From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755884Ab3KALZk (ORCPT ); Fri, 1 Nov 2013 07:25:40 -0400 Received: from mail9.hitachi.co.jp ([133.145.228.44]:42280 "EHLO mail9.hitachi.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751508Ab3KALZi (ORCPT ); Fri, 1 Nov 2013 07:25:38 -0400 Subject: [PATCH -tip v2 2/3] [BUGFIX] kprobes/x86: Prohibit probing on debug_stack_* To: Ingo Molnar From: Masami Hiramatsu Cc: Fenghua Yu , Seiji Aguchi , Ananth N Mavinakayanahalli , x86@kernel.org, lkml , "Steven Rostedt (Red Hat)" , Ingo Molnar , "H. Peter Anvin" , Thomas Gleixner , Borislav Petkov Date: Fri, 01 Nov 2013 11:25:34 +0000 Message-ID: <20131101112534.14657.22729.stgit@kbuild-fedora.novalocal> In-Reply-To: <20131101112530.14657.87835.stgit@kbuild-fedora.novalocal> References: <20131101112530.14657.87835.stgit@kbuild-fedora.novalocal> User-Agent: StGit/0.16 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 Prohibit probing on debug_stack_reset and debug_stack_set_zero. Since the both functions are called from TRACE_IRQS_ON/OFF_DEBUG macros which run in int3 ist entry, probing it may cause a soft lockup. This happens when the kernel built with CONFIG_DYNAMIC_FTRACE=y and CONFIG_TRACE_IRQFLAGS=y. Signed-off-by: Masami Hiramatsu Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Borislav Petkov Cc: Fenghua Yu Cc: Seiji Aguchi --- arch/x86/kernel/cpu/common.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 1789b06..928a4fd 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1157,7 +1157,7 @@ DEFINE_PER_CPU(struct orig_ist, orig_ist); static DEFINE_PER_CPU(unsigned long, debug_stack_addr); DEFINE_PER_CPU(int, debug_stack_usage); -int is_debug_stack(unsigned long addr) +int nokprobe is_debug_stack(unsigned long addr) { return __get_cpu_var(debug_stack_usage) || (addr <= __get_cpu_var(debug_stack_addr) && @@ -1166,13 +1166,13 @@ int is_debug_stack(unsigned long addr) DEFINE_PER_CPU(u32, debug_idt_ctr); -void debug_stack_set_zero(void) +void nokprobe debug_stack_set_zero(void) { this_cpu_inc(debug_idt_ctr); load_current_idt(); } -void debug_stack_reset(void) +void nokprobe debug_stack_reset(void) { if (WARN_ON(!this_cpu_read(debug_idt_ctr))) return;