linux-kernel - [PATCH 8/9] kprobes: Prohibit probing on RCU debug routine

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Message-Id: <154708907005.6325.13292027062251288029.stgit@devbox>
Date:   Thu, 10 Jan 2019 11:57:50 +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 8/9] kprobes: Prohibit probing on RCU debug routine

Since kprobe itself depends on RCU, probing on RCU debug
routine can cause recursive breakpoint problem.
Prohibit probing on RCU debug routines.

int3
 ->do_int3()
   ->ist_enter()
     ->RCU_LOCKDEP_WARN()
       ->debug_lockdep_rcu_enabled() -> int3

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 kernel/rcu/update.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c
index 1971869c4072..f4ca36d92138 100644
--- a/kernel/rcu/update.c
+++ b/kernel/rcu/update.c
@@ -52,6 +52,7 @@
 #include <linux/tick.h>
 #include <linux/rcupdate_wait.h>
 #include <linux/sched/isolation.h>
+#include <linux/kprobes.h>
 
 #define CREATE_TRACE_POINTS
 
@@ -249,6 +250,7 @@ int notrace debug_lockdep_rcu_enabled(void)
 	       current->lockdep_recursion == 0;
 }
 EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled);
+NOKPROBE_SYMBOL(debug_lockdep_rcu_enabled);
 
 /**
  * rcu_read_lock_held() - might we be in RCU read-side critical section?