linux-kernel - [PATCH 7/9] kprobes: Prohibit probing on preempt

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Message-Id: <154708904161.6325.9897869265517636291.stgit@devbox>
Date:   Thu, 10 Jan 2019 11:57:21 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Ingo Molnar <mingo@...hat.com>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>, peterz@...radead.org,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Andrea Righi <righi.andrea@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>, stable@...r.kernel.org
Subject: [PATCH 7/9] kprobes: Prohibit probing on preempt_check debug functions

Since kprobes depends on preempt disable/enable, probing
on the preempt debug routine can cause recursive breakpoint
problem.

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 lib/smp_processor_id.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/lib/smp_processor_id.c b/lib/smp_processor_id.c
index 85925aaa4fff..157d9e31f6c2 100644
--- a/lib/smp_processor_id.c
+++ b/lib/smp_processor_id.c
@@ -5,10 +5,11 @@
  * DEBUG_PREEMPT variant of smp_processor_id().
  */
 #include <linux/export.h>
+#include <linux/kprobes.h>
 #include <linux/sched.h>
 
-notrace static unsigned int check_preemption_disabled(const char *what1,
-							const char *what2)
+notrace static nokprobe_inline
+unsigned int check_preemption_disabled(const char *what1, const char *what2)
 {
 	int this_cpu = raw_smp_processor_id();
 
@@ -56,9 +57,11 @@ notrace unsigned int debug_smp_processor_id(void)
 	return check_preemption_disabled("smp_processor_id", "");
 }
 EXPORT_SYMBOL(debug_smp_processor_id);
+NOKPROBE_SYMBOL(debug_smp_processor_id);
 
 notrace void __this_cpu_preempt_check(const char *op)
 {
 	check_preemption_disabled("__this_cpu_", op);
 }
 EXPORT_SYMBOL(__this_cpu_preempt_check);
+NOKPROBE_SYMBOL(__this_cpu_preempt_check);