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From:   Masami Hiramatsu <mhiramat@kernel.org>
To:     Ingo Molnar <mingo@redhat.com>
Cc:     Masami Hiramatsu <mhiramat@kernel.org>, peterz@infradead.org,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Andrea Righi <righi.andrea@gmail.com>,
        Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH -tip v3 07/10] kprobes: Prohibit probing on preempt_check debug functions
Date:   Wed, 13 Feb 2019 01:14:09 +0900
Message-Id: <154998804911.31052.3541963527929117920.stgit@devbox>
In-Reply-To: <154998785011.31052.1475728497912659748.stgit@devbox>
References: <154998785011.31052.1475728497912659748.stgit@devbox>
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Since kprobes depends on preempt disable/enable, probing
on the preempt debug routine can cause recursive breakpoint
problem.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.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);