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 unsigned long oprofile_started;
  25 static unsigned long is_setup;
  26 static DECLARE_MUTEX(start_sem);
  27
  28 /* timer
  29    0 - use performance monitoring hardware if available
  30    1 - use the timer int mechanism regardless
  31  */
  32 static int timer = 0;
  33
  34 int oprofile_setup(void)
  35 {
  36         int err;
  37
  38         down(&start_sem);
  39
  40         if ((err = alloc_cpu_buffers()))
  41                 goto out;
  42
  43         if ((err = alloc_event_buffer()))
  44                 goto out1;
  45
  46         if (oprofile_ops->setup && (err = oprofile_ops->setup()))
  47                 goto out2;
  48
  49         /* Note even though this starts part of the
  50          * profiling overhead, it's necessary to prevent
  51          * us missing task deaths and eventually oopsing
  52          * when trying to process the event buffer.
  53          */
  54         if ((err = sync_start()))
  55                 goto out3;
  56
  57         is_setup = 1;
  58         up(&start_sem);
  59         return 0;
  60
  61 out3:
  62         if (oprofile_ops->shutdown)
  63                 oprofile_ops->shutdown();
  64 out2:
  65         free_event_buffer();
  66 out1:
  67         free_cpu_buffers();
  68 out:
  69         up(&start_sem);
  70         return err;
  71 }
  72
  73
  74 /* Actually start profiling (echo 1>/dev/oprofile/enable) */
  75 int oprofile_start(void)
  76 {
  77         int err = -EINVAL;
  78
  79         down(&start_sem);
  80
  81         if (!is_setup)
  82                 goto out;
  83
  84         err = 0;
  85
  86         if (oprofile_started)
  87                 goto out;
  88
  89         oprofile_reset_stats();
  90
  91         if ((err = oprofile_ops->start()))
  92                 goto out;
  93
  94         oprofile_started = 1;
  95 out:
  96         up(&start_sem);
  97         return err;
  98 }
  99
 100
 101 /* echo 0>/dev/oprofile/enable */
 102 void oprofile_stop(void)
 103 {
 104         down(&start_sem);
 105         if (!oprofile_started)
 106                 goto out;
 107         oprofile_ops->stop();
 108         oprofile_started = 0;
 109         /* wake up the daemon to read what remains */
 110         wake_up_buffer_waiter();
 111 out:
 112         up(&start_sem);
 113 }
 114
 115
 116 void oprofile_shutdown(void)
 117 {
 118         down(&start_sem);
 119         sync_stop();
 120         if (oprofile_ops->shutdown)
 121                 oprofile_ops->shutdown();
 122         is_setup = 0;
 123         free_event_buffer();
 124         free_cpu_buffers();
 125         up(&start_sem);
 126 }
 127
 128
 129 extern void timer_init(struct oprofile_operations ** ops);
 130
 131
 132 static int __init oprofile_init(void)
 133 {
 134         /* Architecture must fill in the interrupt ops and the
 135          * logical CPU type, or we can fall back to the timer
 136          * interrupt profiler.
 137          */
 138         int err = oprofile_arch_init(&oprofile_ops);
 139
 140         if (err == -ENODEV || timer) {
 141                 timer_init(&oprofile_ops);
 142                 err = 0;
 143         } else if (err) {
 144                 goto out;
 145         }
 146
 147         if (!oprofile_ops->cpu_type) {
 148                 printk(KERN_ERR "oprofile: cpu_type not set !\n");
 149                 err = -EFAULT;
 150         } else {
 151                 err = oprofilefs_register();
 152         }
 153
 154         if (err)
 155                 goto out_exit;
 156 out:
 157         return err;
 158 out_exit:
 159         oprofile_arch_exit();
 160         goto out;
 161 }
 162
 163
 164 static void __exit oprofile_exit(void)
 165 {
 166         oprofilefs_unregister();
 167         oprofile_arch_exit();
 168 }
 169
 170
 171 module_init(oprofile_init);
 172 module_exit(oprofile_exit);
 173
 174 module_param_named(timer, timer, int, 0644);
 175 MODULE_PARM_DESC(timer, "force use of timer interrupt");
 176
 177 MODULE_LICENSE("GPL");
 178 MODULE_AUTHOR("John Levon <levon@movementarian.org>");
 179 MODULE_DESCRIPTION("OProfile system profiler");