From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: [PATCH 5/8] x86,tracing: Mark debug_stack_{set_zero,reset)() notrace Date: Wed, 12 Feb 2020 10:32:15 +0100 Message-ID: <20200212094107.894657838@infradead.org> References: <20200212093210.468391728@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: Received: from merlin.infradead.org ([205.233.59.134]:59452 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728891AbgBLJoA (ORCPT ); Wed, 12 Feb 2020 04:44:00 -0500 Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, rostedt@goodmis.org Cc: peterz@infradead.org, mingo@kernel.org, joel@joelfernandes.org, gregkh@linuxfoundation.org, gustavo@embeddedor.com, tglx@linutronix.de, paulmck@kernel.org, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com Because do_nmi() must not call into tracing outside of nmi_enter()/nmi_exit(), these functions must be notrace. Signed-off-by: Peter Zijlstra (Intel) --- arch/x86/kernel/cpu/common.c | 4 ++-- arch/x86/kernel/nmi.c | 6 ++++++ 2 files changed, 8 insertions(+), 2 deletions(-) --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1690,14 +1690,14 @@ void syscall_init(void) DEFINE_PER_CPU(int, debug_stack_usage); DEFINE_PER_CPU(u32, debug_idt_ctr); -void debug_stack_set_zero(void) +void notrace debug_stack_set_zero(void) { this_cpu_inc(debug_idt_ctr); load_current_idt(); } NOKPROBE_SYMBOL(debug_stack_set_zero); -void debug_stack_reset(void) +void notrace debug_stack_reset(void) { if (WARN_ON(!this_cpu_read(debug_idt_ctr))) return; --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -534,6 +534,9 @@ do_nmi(struct pt_regs *regs, long error_ } #endif + /* + * It is important that no tracing happens before nmi_enter()! + */ nmi_enter(); inc_irq_stat(__nmi_count); @@ -542,6 +545,9 @@ do_nmi(struct pt_regs *regs, long error_ default_do_nmi(regs); nmi_exit(); + /* + * No tracing after nmi_exit()! + */ #ifdef CONFIG_X86_64 if (unlikely(this_cpu_read(update_debug_stack))) {