[tip:perf/core] kprobes: Prohibit probing on RCU debug routine

[tip-bot for Masami Hiramatsu]

Commit-ID:  a39f15b9644fac3f950f522c39e667c3af25c588
Gitweb:     https://git.kernel.org/tip/a39f15b9644fac3f950f522c39e667c3af25c588
Author:     Masami Hiramatsu <mhiramat@xxxxxxxxxx>
AuthorDate: Wed, 13 Feb 2019 01:14:37 +0900
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 13 Feb 2019 08:16:40 +0100

kprobes: Prohibit probing on RCU debug routine

Since kprobe itself depends on RCU, probing on RCU debug
routine can cause recursive breakpoint bugs.

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@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Andrea Righi <righi.andrea@xxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: 154998807741.31052.11229157537816341591.stgit@devbox">http://lkml.kernel.org/r/154998807741.31052.11229157537816341591.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 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?