1 files changed, 135 insertions, 0 deletions

diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 36bf9568ccd9..5c95708b9dc3 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -9,6 +9,7 @@
  *  Copyright (C) 2004-2006 Ingo Molnar
  *  Copyright (C) 2004 William Lee Irwin III
  */
+#include <linux/ring_buffer.h>
 #include <linux/debugfs.h>
 #include <linux/uaccess.h>
 #include <linux/ftrace.h>
@@ -231,9 +232,143 @@ static struct tracer function_trace __read_mostly =
 #endif
 };
 
+#ifdef CONFIG_DYNAMIC_FTRACE
+static void
+ftrace_traceon(unsigned long ip, unsigned long parent_ip, void **data)
+{
+        long *count = (long *)data;
+
+        if (tracing_is_on())
+                return;
+
+        if (!*count)
+                return;
+
+        if (*count != -1)
+                (*count)--;
+
+        tracing_on();
+}
+
+static void
+ftrace_traceoff(unsigned long ip, unsigned long parent_ip, void **data)
+{
+        long *count = (long *)data;
+
+        if (!tracing_is_on())
+                return;
+
+        if (!*count)
+                return;
+
+        if (*count != -1)
+                (*count)--;
+
+        tracing_off();
+}
+
+static struct ftrace_hook_ops traceon_hook_ops = {
+        .func                   = ftrace_traceon,
+};
+
+static struct ftrace_hook_ops traceoff_hook_ops = {
+        .func                   = ftrace_traceoff,
+};
+
+static int
+ftrace_trace_onoff_unreg(char *glob, char *cmd, char *param)
+{
+        struct ftrace_hook_ops *ops;
+
+        /* we register both traceon and traceoff to this callback */
+        if (strcmp(cmd, "traceon") == 0)
+                ops = &traceon_hook_ops;
+        else
+                ops = &traceoff_hook_ops;
+
+        unregister_ftrace_function_hook_func(glob, ops);
+
+        return 0;
+}
+
+static int
+ftrace_trace_onoff_callback(char *glob, char *cmd, char *param, int enable)
+{
+        struct ftrace_hook_ops *ops;
+        void *count = (void *)-1;
+        char *number;
+        int ret;
+
+        /* hash funcs only work with set_ftrace_filter */
+        if (!enable)
+                return -EINVAL;
+
+        if (glob[0] == '!')
+                return ftrace_trace_onoff_unreg(glob+1, cmd, param);
+
+        /* we register both traceon and traceoff to this callback */
+        if (strcmp(cmd, "traceon") == 0)
+                ops = &traceon_hook_ops;
+        else
+                ops = &traceoff_hook_ops;
+
+        if (!param)
+                goto out_reg;
+
+        number = strsep(&param, ":");
+
+        if (!strlen(number))
+                goto out_reg;
+
+        /*
+         * We use the callback data field (which is a pointer)
+         * as our counter.
+         */
+        ret = strict_strtoul(number, 0, (unsigned long *)&count);
+        if (ret)
+                return ret;
+
+ out_reg:
+        ret = register_ftrace_function_hook(glob, ops, count);
+
+        return ret;
+}
+
+static struct ftrace_func_command ftrace_traceon_cmd = {
+        .name                   = "traceon",
+        .func                   = ftrace_trace_onoff_callback,
+};
+
+static struct ftrace_func_command ftrace_traceoff_cmd = {
+        .name                   = "traceoff",
+        .func                   = ftrace_trace_onoff_callback,
+};
+
+static int __init init_func_cmd_traceon(void)
+{
+        int ret;
+
+        ret = register_ftrace_command(&ftrace_traceoff_cmd);
+        if (ret)
+                return ret;
+
+        ret = register_ftrace_command(&ftrace_traceon_cmd);
+        if (ret)
+                unregister_ftrace_command(&ftrace_traceoff_cmd);
+        return ret;
+}
+#else
+static inline int init_func_cmd_traceon(void)
+{
+        return 0;
+}
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
 static __init int init_function_trace(void)
 {
+        init_func_cmd_traceon();
         return register_tracer(&function_trace);
 }
 
 device_initcall(init_function_trace);
+