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From: Peter Zijlstra <peterz@infradead.org>
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
Subject: [PATCH 5/8] x86,tracing: Mark debug_stack_{set_zero,reset)() notrace
Date: Wed, 12 Feb 2020 10:32:15 +0100	[thread overview]
Message-ID: <20200212094107.894657838@infradead.org> (raw)
In-Reply-To: <20200212093210.468391728@infradead.org>

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) <peterz@infradead.org>
---
 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))) {



  parent reply	other threads:[~2020-02-12  9:44 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-12  9:32 [PATCH 0/8] tracing vs rcu vs nmi Peter Zijlstra
2020-02-12  9:32 ` [PATCH 1/8] rcu: Rename rcu_irq_{enter,exit}_irqson() Peter Zijlstra
2020-02-12  9:32 ` [PATCH 2/8] rcu: Mark rcu_dynticks_curr_cpu_in_eqs() inline Peter Zijlstra
2020-02-12  9:32 ` [PATCH 3/8] rcu,tracing: Create trace_rcu_{enter,exit}() Peter Zijlstra
2020-02-12  9:32 ` [PATCH 4/8] sched,rcu,tracing: Mark preempt_count_{add,sub}() notrace Peter Zijlstra
2020-02-12 14:24   ` Steven Rostedt
2020-02-12 15:02     ` Peter Zijlstra
2020-02-12 15:14       ` Steven Rostedt
2020-02-12 15:38         ` Peter Zijlstra
2020-02-12  9:32 ` Peter Zijlstra [this message]
2020-02-12 14:25   ` [PATCH 5/8] x86,tracing: Mark debug_stack_{set_zero,reset)() notrace Steven Rostedt
2020-02-12 15:04     ` Peter Zijlstra
2020-02-12 15:18       ` Steven Rostedt
2020-02-12 15:39         ` Peter Zijlstra
2020-02-12  9:32 ` [PATCH 6/8] perf,tracing: Prepare the perf-trace interface for RCU changes Peter Zijlstra
2020-02-12 14:26   ` Steven Rostedt
2020-02-12 15:07     ` Mathieu Desnoyers
2020-02-12  9:32 ` [PATCH 7/8] tracing: Employ trace_rcu_{enter,exit}() Peter Zijlstra
2020-02-12  9:32 ` [PATCH 8/8] tracing: Remove regular RCU context for _rcuidle tracepoints (again) Peter Zijlstra
2020-02-12 14:29   ` Steven Rostedt
2020-02-12 15:12     ` Peter Zijlstra
2020-02-12 10:01 ` [PATCH 0/8] tracing vs rcu vs nmi Peter Zijlstra
2020-02-12 10:56   ` Will Deacon
2020-02-12 11:58     ` Peter Zijlstra
2020-02-12 14:32     ` Steven Rostedt
2020-02-12 15:21       ` Peter Zijlstra
2020-02-12 10:03 ` Peter Zijlstra
2020-02-12 10:07 ` Peter Zijlstra
2020-02-12 10:09 ` Peter Zijlstra

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