3 files changed, 79 insertions, 2 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 366098d591de..3121b95443d9 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -49,6 +49,7 @@ enum {
         FTRACE_FL_ENABLED       = (1 << 3),
         FTRACE_FL_NOTRACE       = (1 << 4),
         FTRACE_FL_CONVERTED     = (1 << 5),
+        FTRACE_FL_FROZEN        = (1 << 6),
 };
 
 struct dyn_ftrace {
@@ -73,15 +74,18 @@ extern void ftrace_caller(void);
 extern void ftrace_call(void);
 extern void mcount_call(void);
 
+extern int skip_trace(unsigned long ip);
+
 void ftrace_disable_daemon(void);
 void ftrace_enable_daemon(void);
 
 #else
+# define skip_trace(ip)                         ({ 0; })
 # define ftrace_force_update()                  ({ 0; })
 # define ftrace_set_filter(buf, len, reset)     do { } while (0)
 # define ftrace_disable_daemon()                do { } while (0)
 # define ftrace_enable_daemon()                 do { } while (0)
-#endif
+#endif /* CONFIG_DYNAMIC_FTRACE */
 
 /* totally disable ftrace - can not re-enable after this */
 void ftrace_kill(void);
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f1e9e5c74e64..d1238163155f 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -163,6 +163,8 @@ enum {
 };
 
 static int ftrace_filtered;
+static int tracing_on;
+static int frozen_record_count;
 
 static struct hlist_head ftrace_hash[FTRACE_HASHSIZE];
 
@@ -195,6 +197,71 @@ static int ftrace_record_suspend;
 
 static struct dyn_ftrace *ftrace_free_records;
 
+
+#ifdef CONFIG_KPROBES
+static inline void freeze_record(struct dyn_ftrace *rec)
+{
+        if (!(rec->flags & FTRACE_FL_FROZEN)) {
+                rec->flags |= FTRACE_FL_FROZEN;
+                frozen_record_count++;
+        }
+}
+
+static inline void unfreeze_record(struct dyn_ftrace *rec)
+{
+        if (rec->flags & FTRACE_FL_FROZEN) {
+                rec->flags &= ~FTRACE_FL_FROZEN;
+                frozen_record_count--;
+        }
+}
+
+static inline int record_frozen(struct dyn_ftrace *rec)
+{
+        return rec->flags & FTRACE_FL_FROZEN;
+}
+#else
+# define freeze_record(rec)                     ({ 0; })
+# define unfreeze_record(rec)                   ({ 0; })
+# define record_frozen(rec)                     ({ 0; })
+#endif /* CONFIG_KPROBES */
+
+int skip_trace(unsigned long ip)
+{
+        unsigned long fl;
+        struct dyn_ftrace *rec;
+        struct hlist_node *t;
+        struct hlist_head *head;
+
+        if (frozen_record_count == 0)
+                return 0;
+
+        head = &ftrace_hash[hash_long(ip, FTRACE_HASHBITS)];
+        hlist_for_each_entry_rcu(rec, t, head, node) {
+                if (rec->ip == ip) {
+                        if (record_frozen(rec)) {
+                                if (rec->flags & FTRACE_FL_FAILED)
+                                        return 1;
+
+                                if (!(rec->flags & FTRACE_FL_CONVERTED))
+                                        return 1;
+
+                                if (!tracing_on || !ftrace_enabled)
+                                        return 1;
+
+                                if (ftrace_filtered) {
+                                        fl = rec->flags & (FTRACE_FL_FILTER |
+                                                           FTRACE_FL_NOTRACE);
+                                        if (!fl || (fl & FTRACE_FL_NOTRACE))
+                                                return 1;
+                                }
+                        }
+                        break;
+                }
+        }
+
+        return 0;
+}
+
 static inline int
 ftrace_ip_in_hash(unsigned long ip, unsigned long key)
 {
@@ -489,8 +556,11 @@ static int __ftrace_modify_code(void *data)
                  */
                 __ftrace_update_code(NULL);
                 ftrace_replace_code(1);
-        } else if (*command & FTRACE_DISABLE_CALLS)
+                tracing_on = 1;
+        } else if (*command & FTRACE_DISABLE_CALLS) {
                 ftrace_replace_code(0);
+                tracing_on = 0;
+        }
 
         if (*command & FTRACE_UPDATE_TRACE_FUNC)
                 ftrace_update_ftrace_func(ftrace_trace_function);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 6e9dae7eb418..9ade79369bfb 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -988,6 +988,9 @@ function_trace_call(unsigned long ip, unsigned long parent_ip)
         if (unlikely(!tracer_enabled))
                 return;
 
+        if (skip_trace(ip))
+                return;
+
         local_irq_save(flags);
         cpu = raw_smp_processor_id();
         data = tr->data[cpu];