trunk/attic/marker-loader/marker-loader.c

   1 /* marker-loader.c
   2  *
   3  * Marker Loader
   4  *
   5  * Loads a function at a marker call site.
   6  *
   7  * (C) Copyright 2006 Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
   8  *
   9  * This file is released under the GPLv2.
  10  * See the file COPYING for more details.
  11  */
  12
  13 #include <linux/marker.h>
  14 #include <linux/module.h>
  15 #include <linux/kallsyms.h>
  16
  17 /* function to install */
  18 void do_mark1(const char *format, int value)
  19 {
  20         printk("value is %d\n", value);
  21 }
  22
  23 static void *saved_over;
  24
  25 static void **target_mark_call;
  26 static void **target_mark_jump_over;
  27 static void **target_mark_jump_call;
  28 static void **target_mark_jump_inline;
  29
  30 void show_symbol_pointers(void)
  31 {
  32         printk("Marker loader : Loading symbols...\n");
  33         printk("  %s %p %p\n", __stringify(CALL), target_mark_call,
  34                 target_mark_call?*target_mark_call:0x0);
  35         printk("  %s %p %p\n", __stringify(JUMP_OVER), target_mark_jump_over,
  36                 target_mark_jump_over?*target_mark_jump_over:0x0);
  37         printk("  %s %p %p\n", __stringify(JUMP_CALL), target_mark_jump_call,
  38                 target_mark_jump_call?*target_mark_jump_call:0x0);
  39         printk("  %s %p %p\n", __stringify(JUMP_INLINE), target_mark_jump_inline,
  40                 target_mark_jump_inline?*target_mark_jump_inline:0x0);
  41 }
  42
  43 int mark_install_hook(void)
  44 {
  45         target_mark_call = (void**)kallsyms_lookup_name(__stringify(CALL));
  46         target_mark_jump_over = (void**)kallsyms_lookup_name(__stringify(JUMP_OVER));
  47         target_mark_jump_call = (void**)kallsyms_lookup_name(__stringify(JUMP_CALL));
  48         target_mark_jump_inline = (void**)kallsyms_lookup_name(__stringify(JUMP_INLINE));
  49
  50         show_symbol_pointers();
  51
  52         if(!(target_mark_call && target_mark_jump_over && target_mark_jump_call &&
  53                 target_mark_jump_inline)) {
  54                 printk("Target symbols missing in kallsyms.\n");
  55                 return -EPERM;
  56         }
  57
  58         printk("Installing hook\n");
  59         *target_mark_call = (void*)do_mark1;
  60         saved_over = *target_mark_jump_over;
  61         *target_mark_jump_over = *target_mark_jump_call;
  62
  63         return 0;
  64 }
  65
  66 int init_module(void)
  67 {
  68         return mark_install_hook();
  69 }
  70
  71 void cleanup_module(void)
  72 {
  73         printk("Removing hook\n");
  74         *target_mark_jump_over = saved_over;
  75         *target_mark_call = __mark_empty_function;
  76
  77         /* Wait for instrumentation functions to return before quitting */
  78         synchronize_sched();
  79 }
  80
  81 MODULE_LICENSE("GPL");
  82 MODULE_AUTHOR("Mathieu Desnoyers");
  83 MODULE_DESCRIPTION("Marker Loader");
  84