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Date: Tue, 05 May 2020 15:16:33 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: x86@...nel.org, "Paul E. McKenney" <paulmck@...nel.org>,
Andy Lutomirski <luto@...nel.org>,
Alexandre Chartre <alexandre.chartre@...cle.com>,
Frederic Weisbecker <frederic@...nel.org>,
Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <sean.j.christopherson@...el.com>,
Masami Hiramatsu <mhiramat@...nel.org>,
Petr Mladek <pmladek@...e.com>,
Steven Rostedt <rostedt@...dmis.org>,
Joel Fernandes <joel@...lfernandes.org>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
Juergen Gross <jgross@...e.com>,
Brian Gerst <brgerst@...il.com>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Josh Poimboeuf <jpoimboe@...hat.com>,
Will Deacon <will@...nel.org>,
"Peter Zijlstra (Intel)" <peterz@...radead.org>
Subject: [patch V4 part 1 31/36] printk: Disallow instrumenting print_nmi_enter()
From: Peter Zijlstra <peterz@...radead.org>
It happens early in nmi_enter(), no tracing, probing or other funnies
allowed. Specifically as nmi_enter() will be used in do_debug(), which
would cause recursive exceptions when kprobed.
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
kernel/printk/printk_safe.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/kernel/printk/printk_safe.c
+++ b/kernel/printk/printk_safe.c
@@ -10,6 +10,7 @@
#include <linux/cpumask.h>
#include <linux/irq_work.h>
#include <linux/printk.h>
+#include <linux/kprobes.h>
#include "internal.h"
@@ -293,12 +294,12 @@ static __printf(1, 0) int vprintk_nmi(co
return printk_safe_log_store(s, fmt, args);
}
-void notrace printk_nmi_enter(void)
+void noinstr printk_nmi_enter(void)
{
this_cpu_add(printk_context, PRINTK_NMI_CONTEXT_OFFSET);
}
-void notrace printk_nmi_exit(void)
+void noinstr printk_nmi_exit(void)
{
this_cpu_sub(printk_context, PRINTK_NMI_CONTEXT_OFFSET);
}
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