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 <linux/workqueue.h>
  16 #include <linux/time.h>
  17 #include <asm/mutex.h>
  18
  19 #include "oprof.h"
  20 #include "event_buffer.h"
  21 #include "cpu_buffer.h"
  22 #include "buffer_sync.h"
  23 #include "oprofile_stats.h"
  24
  25 static unsigned long is_setup;
  26 static void switch_worker(struct work_struct *work);
  27 static DECLARE_DELAYED_WORK(switch_work, switch_worker);
  28 static DEFINE_MUTEX(start_mutex);
  29
  30 struct oprofile_operations oprofile_ops;
  31
  32 unsigned long timeout_jiffies;
  33 unsigned long oprofile_started;
  34 unsigned long backtrace_depth;
  35 /* Multiplexing defaults at 1 msec*/
  36
  37 /* timer
  38    0 - use performance monitoring hardware if available
  39    1 - use the timer int mechanism regardless
  40  */
  41 static int timer = 0;
  42
  43 int oprofile_setup(void)
  44 {
  45         int err;
  46
  47         mutex_lock(&start_mutex);
  48
  49         if ((err = alloc_cpu_buffers()))
  50                 goto out;
  51
  52         if ((err = alloc_event_buffer()))
  53                 goto out1;
  54
  55         if (oprofile_ops.setup && (err = oprofile_ops.setup()))
  56                 goto out2;
  57
  58         /* Note even though this starts part of the
  59          * profiling overhead, it's necessary to prevent
  60          * us missing task deaths and eventually oopsing
  61          * when trying to process the event buffer.
  62          */
  63         if (oprofile_ops.sync_start) {
  64                 int sync_ret = oprofile_ops.sync_start();
  65                 switch (sync_ret) {
  66                 case 0:
  67                         goto post_sync;
  68                 case 1:
  69                         goto do_generic;
  70                 case -1:
  71                         goto out3;
  72                 default:
  73                         goto out3;
  74                 }
  75         }
  76 do_generic:
  77         if ((err = sync_start()))
  78                 goto out3;
  79
  80 post_sync:
  81         is_setup = 1;
  82         mutex_unlock(&start_mutex);
  83         return 0;
  84
  85 out3:
  86         if (oprofile_ops.shutdown)
  87                 oprofile_ops.shutdown();
  88 out2:
  89         free_event_buffer();
  90 out1:
  91         free_cpu_buffers();
  92 out:
  93         mutex_unlock(&start_mutex);
  94         return err;
  95 }
  96
  97 static void start_switch_worker(void)
  98 {
  99         schedule_delayed_work(&switch_work, timeout_jiffies);
 100 }
 101
 102 static void switch_worker(struct work_struct *work)
 103 {
 104         if (!oprofile_ops.switch_events())
 105                 start_switch_worker();
 106 }
 107
 108 /* Actually start profiling (echo 1>/dev/oprofile/enable) */
 109 int oprofile_start(void)
 110 {
 111         int err = -EINVAL;
 112
 113         mutex_lock(&start_mutex);
 114         if (!is_setup)
 115                 goto out;
 116
 117         err = 0;
 118
 119         if (oprofile_started)
 120                 goto out;
 121
 122         oprofile_reset_stats();
 123
 124         if ((err = oprofile_ops.start()))
 125                 goto out;
 126
 127         if (oprofile_ops.switch_events)
 128                 start_switch_worker();
 129
 130         oprofile_started = 1;
 131 out:
 132         mutex_unlock(&start_mutex);
 133         return err;
 134 }
 135
 136
 137 /* echo 0>/dev/oprofile/enable */
 138 void oprofile_stop(void)
 139 {
 140         mutex_lock(&start_mutex);
 141         if (!oprofile_started)
 142                 goto out;
 143         oprofile_ops.stop();
 144         oprofile_started = 0;
 145         cancel_delayed_work_sync(&switch_work);
 146         /* wake up the daemon to read what remains */
 147         wake_up_buffer_waiter();
 148 out:
 149         mutex_unlock(&start_mutex);
 150 }
 151
 152
 153 void oprofile_shutdown(void)
 154 {
 155         mutex_lock(&start_mutex);
 156         if (oprofile_ops.sync_stop) {
 157                 int sync_ret = oprofile_ops.sync_stop();
 158                 switch (sync_ret) {
 159                 case 0:
 160                         goto post_sync;
 161                 case 1:
 162                         goto do_generic;
 163                 default:
 164                         goto post_sync;
 165                 }
 166         }
 167 do_generic:
 168         sync_stop();
 169 post_sync:
 170         if (oprofile_ops.shutdown)
 171                 oprofile_ops.shutdown();
 172         is_setup = 0;
 173         free_event_buffer();
 174         free_cpu_buffers();
 175         mutex_unlock(&start_mutex);
 176 }
 177
 178 /* User inputs in ms, converts to jiffies */
 179 int oprofile_set_timeout(unsigned long val_msec)
 180 {
 181         int err = 0;
 182
 183         mutex_lock(&start_mutex);
 184
 185         if (oprofile_started) {
 186                 err = -EBUSY;
 187                 goto out;
 188         }
 189
 190         if (!oprofile_ops.switch_events) {
 191                 err = -EINVAL;
 192                 goto out;
 193         }
 194
 195         timeout_jiffies = msecs_to_jiffies(val_msec);
 196         if (timeout_jiffies == MAX_JIFFY_OFFSET)
 197                 timeout_jiffies = msecs_to_jiffies(1);
 198
 199 out:
 200         mutex_unlock(&start_mutex);
 201         return err;
 202
 203 }
 204
 205 int oprofile_set_backtrace(unsigned long val)
 206 {
 207         int err = 0;
 208
 209         mutex_lock(&start_mutex);
 210
 211         if (oprofile_started) {
 212                 err = -EBUSY;
 213                 goto out;
 214         }
 215
 216         if (!oprofile_ops.backtrace) {
 217                 err = -EINVAL;
 218                 goto out;
 219         }
 220
 221         backtrace_depth = val;
 222
 223 out:
 224         mutex_unlock(&start_mutex);
 225         return err;
 226 }
 227
 228 static void __init oprofile_switch_timer_init(void)
 229 {
 230         timeout_jiffies = msecs_to_jiffies(1);
 231 }
 232
 233 static int __init oprofile_init(void)
 234 {
 235         int err;
 236
 237         oprofile_switch_timer_init();
 238         err = oprofile_arch_init(&oprofile_ops);
 239
 240         if (err < 0 || timer) {
 241                 printk(KERN_INFO "oprofile: using timer interrupt.\n");
 242                 oprofile_timer_init(&oprofile_ops);
 243         }
 244
 245         err = oprofilefs_register();
 246         if (err)
 247                 oprofile_arch_exit();
 248
 249         return err;
 250 }
 251
 252
 253 static void __exit oprofile_exit(void)
 254 {
 255         oprofilefs_unregister();
 256         oprofile_arch_exit();
 257 }
 258
 259
 260 module_init(oprofile_init);
 261 module_exit(oprofile_exit);
 262
 263 module_param_named(timer, timer, int, 0644);
 264 MODULE_PARM_DESC(timer, "force use of timer interrupt");
 265
 266 MODULE_LICENSE("GPL");
 267 MODULE_AUTHOR("John Levon <levon@movementarian.org>");
 268 MODULE_DESCRIPTION("OProfile system profiler");