drivers/oprofile/oprof.c

   1 /**
   2  * @file oprof.c
   3  *
   4  * @remark Copyright 2002 OProfile authors
   5  * @remark Read the file COPYING
   6  *
   7  * @author John Levon <levon@movementarian.org>
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/init.h>
  13 #include <linux/oprofile.h>
  14 #include <linux/moduleparam.h>
  15 #include <asm/semaphore.h>
  16
  17 #include "oprof.h"
  18 #include "event_buffer.h"
  19 #include "cpu_buffer.h"
  20 #include "buffer_sync.h"
  21 #include "oprofile_stats.h"
  22
  23 struct oprofile_operations oprofile_ops;
  24
  25 unsigned long oprofile_started;
  26 unsigned long backtrace_depth;
  27 static unsigned long is_setup;
  28 static DECLARE_MUTEX(start_sem);
  29
  30 /* timer
  31    0 - use performance monitoring hardware if available
  32    1 - use the timer int mechanism regardless
  33  */
  34 static int timer = 0;
  35
  36 int oprofile_setup(void)
  37 {
  38         int err;
  39
  40         down(&start_sem);
  41
  42         if ((err = alloc_cpu_buffers()))
  43                 goto out;
  44
  45         if ((err = alloc_event_buffer()))
  46                 goto out1;
  47
  48         if (oprofile_ops.setup && (err = oprofile_ops.setup()))
  49                 goto out2;
  50
  51         /* Note even though this starts part of the
  52          * profiling overhead, it's necessary to prevent
  53          * us missing task deaths and eventually oopsing
  54          * when trying to process the event buffer.
  55          */
  56         if ((err = sync_start()))
  57                 goto out3;
  58
  59         is_setup = 1;
  60         up(&start_sem);
  61         return 0;
  62
  63 out3:
  64         if (oprofile_ops.shutdown)
  65                 oprofile_ops.shutdown();
  66 out2:
  67         free_event_buffer();
  68 out1:
  69         free_cpu_buffers();
  70 out:
  71         up(&start_sem);
  72         return err;
  73 }
  74
  75
  76 /* Actually start profiling (echo 1>/dev/oprofile/enable) */
  77 int oprofile_start(void)
  78 {
  79         int err = -EINVAL;
  80
  81         down(&start_sem);
  82
  83         if (!is_setup)
  84                 goto out;
  85
  86         err = 0;
  87
  88         if (oprofile_started)
  89                 goto out;
  90
  91         oprofile_reset_stats();
  92
  93         if ((err = oprofile_ops.start()))
  94                 goto out;
  95
  96         oprofile_started = 1;
  97 out:
  98         up(&start_sem);
  99         return err;
 100 }
 101
 102
 103 /* echo 0>/dev/oprofile/enable */
 104 void oprofile_stop(void)
 105 {
 106         down(&start_sem);
 107         if (!oprofile_started)
 108                 goto out;
 109         oprofile_ops.stop();
 110         oprofile_started = 0;
 111         /* wake up the daemon to read what remains */
 112         wake_up_buffer_waiter();
 113 out:
 114         up(&start_sem);
 115 }
 116
 117
 118 void oprofile_shutdown(void)
 119 {
 120         down(&start_sem);
 121         sync_stop();
 122         if (oprofile_ops.shutdown)
 123                 oprofile_ops.shutdown();
 124         is_setup = 0;
 125         free_event_buffer();
 126         free_cpu_buffers();
 127         up(&start_sem);
 128 }
 129
 130
 131 int oprofile_set_backtrace(unsigned long val)
 132 {
 133         int err = 0;
 134
 135         down(&start_sem);
 136
 137         if (oprofile_started) {
 138                 err = -EBUSY;
 139                 goto out;
 140         }
 141
 142         if (!oprofile_ops.backtrace) {
 143                 err = -EINVAL;
 144                 goto out;
 145         }
 146
 147         backtrace_depth = val;
 148
 149 out:
 150         up(&start_sem);
 151         return err;
 152 }
 153
 154 static int __init oprofile_init(void)
 155 {
 156         int err;
 157
 158         err = oprofile_arch_init(&oprofile_ops);
 159
 160         if (err < 0 || timer) {
 161                 printk(KERN_INFO "oprofile: using timer interrupt.\n");
 162                 oprofile_timer_init(&oprofile_ops);
 163         }
 164
 165         err = oprofilefs_register();
 166         if (err)
 167                 oprofile_arch_exit();
 168
 169         return err;
 170 }
 171
 172
 173 static void __exit oprofile_exit(void)
 174 {
 175         oprofilefs_unregister();
 176         oprofile_arch_exit();
 177 }
 178
 179
 180 module_init(oprofile_init);
 181 module_exit(oprofile_exit);
 182
 183 module_param_named(timer, timer, int, 0644);
 184 MODULE_PARM_DESC(timer, "force use of timer interrupt");
 185
 186 MODULE_LICENSE("GPL");
 187 MODULE_AUTHOR("John Levon <levon@movementarian.org>");
 188 MODULE_DESCRIPTION("OProfile system profiler");