lib/ctracer_relay.c

   1 /*
   2   Copyright (C) 2007 Arnaldo Carvalho de Melo <acme@redhat.com>
   3
   4   This program is free software; you can redistribute it and/or modify it
   5   under the terms of version 2 of the GNU General Public License as
   6   published by the Free Software Foundation.
   7 */
   8 #include <linux/kernel.h>
   9 #include <linux/debugfs.h>
  10 #include <linux/fs.h>
  11 #include <linux/percpu.h>
  12 #include <linux/relay.h>
  13 #include <linux/sched.h>
  14 #include <linux/string.h>
  15 #include <linux/module.h>
  16 #include "ctracer_relay.h"
  17
  18 static struct rchan *ctracer__rchan;
  19
  20 static int ctracer__subbuf_start_callback(struct rchan_buf *buf, void *subbuf,
  21                                           void *prev_subbuf,
  22                                           size_t prev_padding)
  23 {
  24         static int warned;
  25         if (!relay_buf_full(buf))
  26                 return 1;
  27         if (!warned) {
  28                 warned = 1;
  29                 printk("relay_buf_full!\n");
  30         }
  31         return 0;
  32 }
  33
  34 static struct dentry *ctracer__create_buf_file_callback(const char *filename,
  35                                                         struct dentry *parent,
  36                                                         int mode,
  37                                                         struct rchan_buf *buf,
  38                                                         int *is_global)
  39 {
  40         return debugfs_create_file(filename, mode, parent, buf,
  41                                    &relay_file_operations);
  42 }
  43
  44 static int ctracer__remove_buf_file_callback(struct dentry *dentry)
  45 {
  46         debugfs_remove(dentry);
  47         return 0;
  48 }
  49
  50 static struct rchan_callbacks ctracer__relay_callbacks = {
  51         .subbuf_start    = ctracer__subbuf_start_callback,
  52         .create_buf_file = ctracer__create_buf_file_callback,
  53         .remove_buf_file = ctracer__remove_buf_file_callback,
  54 };
  55
  56 extern void ctracer__class_state(const void *from, void *to);
  57
  58 void ctracer__method_hook(const unsigned long long now,
  59                           const int probe_type,
  60                           const unsigned long long function_id,
  61                           const void *object, const int state_len)
  62 {
  63         if (object != NULL) {
  64                 void *t = relay_reserve(ctracer__rchan,
  65                                         sizeof(struct trace_entry) + state_len);
  66
  67                 if (t != NULL) {
  68                         struct trace_entry *entry = t;
  69
  70                         entry->nsec        = now;
  71                         entry->probe_type  = probe_type;
  72                         entry->object      = object;
  73                         entry->function_id = function_id;
  74                         ctracer__class_state(object, t + sizeof(*entry));
  75                 }
  76         }
  77 }
  78
  79 EXPORT_SYMBOL_GPL(ctracer__method_hook);
  80
  81 static int __init ctracer__relay_init(void)
  82 {
  83         ctracer__rchan = relay_open("ctracer", NULL, 512 * 1024, 64,
  84                                     &ctracer__relay_callbacks, NULL);
  85         if (ctracer__rchan == NULL) {
  86                 pr_info("ctracer: couldn't create the relay\n");
  87                 return -1;
  88         }
  89         return 0;
  90 }
  91
  92 module_init(ctracer__relay_init);
  93
  94 static void __exit ctracer__relay_exit(void)
  95 {
  96         relay_close(ctracer__rchan);
  97 }
  98
  99 module_exit(ctracer__relay_exit);
 100
 101 MODULE_LICENSE("GPL");