kernel/trace/trace_functions.c

   1 /*
   2  * ring buffer based function tracer
   3  *
   4  * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
   5  * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
   6  *
   7  * Based on code from the latency_tracer, that is:
   8  *
   9  *  Copyright (C) 2004-2006 Ingo Molnar
  10  *  Copyright (C) 2004 William Lee Irwin III
  11  */
  12 #include <linux/debugfs.h>
  13 #include <linux/uaccess.h>
  14 #include <linux/ftrace.h>
  15 #include <linux/fs.h>
  16
  17 #include "trace.h"
  18
  19 static void function_reset(struct trace_array *tr)
  20 {
  21         int cpu;
  22
  23         tr->time_start = ftrace_now(tr->cpu);
  24
  25         for_each_online_cpu(cpu)
  26                 tracing_reset(tr->data[cpu]);
  27 }
  28
  29 static void start_function_trace(struct trace_array *tr)
  30 {
  31         function_reset(tr);
  32         tracing_start_cmdline_record();
  33         tracing_start_function_trace();
  34 }
  35
  36 static void stop_function_trace(struct trace_array *tr)
  37 {
  38         tracing_stop_function_trace();
  39         tracing_stop_cmdline_record();
  40 }
  41
  42 static void function_trace_init(struct trace_array *tr)
  43 {
  44         if (tr->ctrl)
  45                 start_function_trace(tr);
  46 }
  47
  48 static void function_trace_reset(struct trace_array *tr)
  49 {
  50         if (tr->ctrl)
  51                 stop_function_trace(tr);
  52 }
  53
  54 static void function_trace_ctrl_update(struct trace_array *tr)
  55 {
  56         if (tr->ctrl)
  57                 start_function_trace(tr);
  58         else
  59                 stop_function_trace(tr);
  60 }
  61
  62 static struct tracer function_trace __read_mostly =
  63 {
  64         .name        = "ftrace",
  65         .init        = function_trace_init,
  66         .reset       = function_trace_reset,
  67         .ctrl_update = function_trace_ctrl_update,
  68 #ifdef CONFIG_FTRACE_SELFTEST
  69         .selftest    = trace_selftest_startup_function,
  70 #endif
  71 };
  72
  73 static __init int init_function_trace(void)
  74 {
  75         return register_tracer(&function_trace);
  76 }
  77
  78 device_initcall(init_function_trace);