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 notrace 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 notrace void start_function_trace(struct trace_array *tr)
  30 {
  31         function_reset(tr);
  32         tracing_start_function_trace();
  33 }
  34
  35 static notrace void stop_function_trace(struct trace_array *tr)
  36 {
  37         tracing_stop_function_trace();
  38 }
  39
  40 static notrace void function_trace_init(struct trace_array *tr)
  41 {
  42         if (tr->ctrl)
  43                 start_function_trace(tr);
  44 }
  45
  46 static notrace void function_trace_reset(struct trace_array *tr)
  47 {
  48         if (tr->ctrl)
  49                 stop_function_trace(tr);
  50 }
  51
  52 static notrace void function_trace_ctrl_update(struct trace_array *tr)
  53 {
  54         if (tr->ctrl)
  55                 start_function_trace(tr);
  56         else
  57                 stop_function_trace(tr);
  58 }
  59
  60 static struct tracer function_trace __read_mostly =
  61 {
  62         .name        = "ftrace",
  63         .init        = function_trace_init,
  64         .reset       = function_trace_reset,
  65         .ctrl_update = function_trace_ctrl_update,
  66 #ifdef CONFIG_FTRACE_SELFTEST
  67         .selftest    = trace_selftest_startup_function,
  68 #endif
  69 };
  70
  71 static __init int init_function_trace(void)
  72 {
  73         return register_tracer(&function_trace);
  74 }
  75
  76 device_initcall(init_function_trace);