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/mutex.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 oprofile_backtrace_depth;
  27 static unsigned long is_setup;
  28 static DEFINE_MUTEX(start_mutex);
  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         mutex_lock(&start_mutex);
  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 (oprofile_ops.sync_start) {
  57                 int sync_ret = oprofile_ops.sync_start();
  58                 switch (sync_ret) {
  59                 case 0:
  60                         goto post_sync;
  61                 case 1:
  62                         goto do_generic;
  63                 case -1:
  64                         goto out3;
  65                 default:
  66                         goto out3;
  67                 }
  68         }
  69 do_generic:
  70         if ((err = sync_start()))
  71                 goto out3;
  72
  73 post_sync:
  74         is_setup = 1;
  75         mutex_unlock(&start_mutex);
  76         return 0;
  77
  78 out3:
  79         if (oprofile_ops.shutdown)
  80                 oprofile_ops.shutdown();
  81 out2:
  82         free_event_buffer();
  83 out1:
  84         free_cpu_buffers();
  85 out:
  86         mutex_unlock(&start_mutex);
  87         return err;
  88 }
  89
  90
  91 /* Actually start profiling (echo 1>/dev/oprofile/enable) */
  92 int oprofile_start(void)
  93 {
  94         int err = -EINVAL;
  95
  96         mutex_lock(&start_mutex);
  97
  98         if (!is_setup)
  99                 goto out;
 100
 101         err = 0;
 102
 103         if (oprofile_started)
 104                 goto out;
 105
 106         oprofile_reset_stats();
 107
 108         if ((err = oprofile_ops.start()))
 109                 goto out;
 110
 111         oprofile_started = 1;
 112 out:
 113         mutex_unlock(&start_mutex);
 114         return err;
 115 }
 116
 117
 118 /* echo 0>/dev/oprofile/enable */
 119 void oprofile_stop(void)
 120 {
 121         mutex_lock(&start_mutex);
 122         if (!oprofile_started)
 123                 goto out;
 124         oprofile_ops.stop();
 125         oprofile_started = 0;
 126         /* wake up the daemon to read what remains */
 127         wake_up_buffer_waiter();
 128 out:
 129         mutex_unlock(&start_mutex);
 130 }
 131
 132
 133 void oprofile_shutdown(void)
 134 {
 135         mutex_lock(&start_mutex);
 136         if (oprofile_ops.sync_stop) {
 137                 int sync_ret = oprofile_ops.sync_stop();
 138                 switch (sync_ret) {
 139                 case 0:
 140                         goto post_sync;
 141                 case 1:
 142                         goto do_generic;
 143                 default:
 144                         goto post_sync;
 145                 }
 146         }
 147 do_generic:
 148         sync_stop();
 149 post_sync:
 150         if (oprofile_ops.shutdown)
 151                 oprofile_ops.shutdown();
 152         is_setup = 0;
 153         free_event_buffer();
 154         free_cpu_buffers();
 155         mutex_unlock(&start_mutex);
 156 }
 157
 158
 159 int oprofile_set_backtrace(unsigned long val)
 160 {
 161         int err = 0;
 162
 163         mutex_lock(&start_mutex);
 164
 165         if (oprofile_started) {
 166                 err = -EBUSY;
 167                 goto out;
 168         }
 169
 170         if (!oprofile_ops.backtrace) {
 171                 err = -EINVAL;
 172                 goto out;
 173         }
 174
 175         oprofile_backtrace_depth = val;
 176
 177 out:
 178         mutex_unlock(&start_mutex);
 179         return err;
 180 }
 181
 182 static int __init oprofile_init(void)
 183 {
 184         int err;
 185
 186         err = oprofile_arch_init(&oprofile_ops);
 187
 188         if (err < 0 || timer) {
 189                 printk(KERN_INFO "oprofile: using timer interrupt.\n");
 190                 oprofile_timer_init(&oprofile_ops);
 191         }
 192
 193         err = oprofilefs_register();
 194         if (err)
 195                 oprofile_arch_exit();
 196
 197         return err;
 198 }
 199
 200
 201 static void __exit oprofile_exit(void)
 202 {
 203         oprofilefs_unregister();
 204         oprofile_arch_exit();
 205 }
 206
 207
 208 module_init(oprofile_init);
 209 module_exit(oprofile_exit);
 210
 211 module_param_named(timer, timer, int, 0644);
 212 MODULE_PARM_DESC(timer, "force use of timer interrupt");
 213
 214 MODULE_LICENSE("GPL");
 215 MODULE_AUTHOR("John Levon <levon@movementarian.org>");
 216 MODULE_DESCRIPTION("OProfile system profiler");