ftrace: Add check for NULL regs if ops has SAVE_REGS set

[karo-tx-linux.git] / kernel / trace / ftrace.c

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 67708f46baaefbd6bca64a34a213c2cc7fda5074..8ce9eefc5bb4f6aae3ffa520152a51eb033adb1e 100644 (file)
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1441,12 +1441,22 @@ ftrace_hash_move(struct ftrace_ops *ops, int enable,
  * the hashes are freed with call_rcu_sched().
  */
 static int
-ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip)
+ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs)
 {
        struct ftrace_hash *filter_hash;
        struct ftrace_hash *notrace_hash;
        int ret;
 
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+       /*
+        * There's a small race when adding ops that the ftrace handler
+        * that wants regs, may be called without them. We can not
+        * allow that handler to be called if regs is NULL.
+        */
+       if (regs == NULL && (ops->flags & FTRACE_OPS_FL_SAVE_REGS))
+               return 0;
+#endif
+
        filter_hash = rcu_dereference_raw_notrace(ops->filter_hash);
        notrace_hash = rcu_dereference_raw_notrace(ops->notrace_hash);
 
@@ -4218,7 +4228,7 @@ static inline void ftrace_startup_enable(int command) { }
 # define ftrace_shutdown_sysctl()      do { } while (0)
 
 static inline int
-ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip)
+ftrace_ops_test(struct ftrace_ops *ops, unsigned long ip, void *regs)
 {
        return 1;
 }
@@ -4241,7 +4251,7 @@ ftrace_ops_control_func(unsigned long ip, unsigned long parent_ip,
        do_for_each_ftrace_op(op, ftrace_control_list) {
                if (!(op->flags & FTRACE_OPS_FL_STUB) &&
                    !ftrace_function_local_disabled(op) &&
-                   ftrace_ops_test(op, ip))
+                   ftrace_ops_test(op, ip, regs))
                        op->func(ip, parent_ip, op, regs);
        } while_for_each_ftrace_op(op);
        trace_recursion_clear(TRACE_CONTROL_BIT);
@@ -4274,7 +4284,7 @@ __ftrace_ops_list_func(unsigned long ip, unsigned long parent_ip,
         */
        preempt_disable_notrace();
        do_for_each_ftrace_op(op, ftrace_ops_list) {
-               if (ftrace_ops_test(op, ip))
+               if (ftrace_ops_test(op, ip, regs))
                        op->func(ip, parent_ip, op, regs);
        } while_for_each_ftrace_op(op);
        preempt_enable_notrace();