trunk/tests/kernel/test-kprobes.c

   1 /* test-kprobes.c
   2  *
   3  * kprobe timing test.
   4  */
   5
   6 #include <linux/kernel.h>
   7 #include <linux/module.h>
   8 #include <linux/kprobes.h>
   9 #include <linux/kallsyms.h>
  10 #include <linux/sched.h>
  11
  12
  13 /*For each probe you need to allocate a kprobe structure*/
  14 static struct kprobe kp;
  15
  16 /*kprobe pre_handler: called just before the probed instruction is executed*/
  17 int handler_pre(struct kprobe *p, struct pt_regs *regs)
  18 {
  19         //printk("pre_handler: p->addr=0x%p, eip=%lx, eflags=0x%lx\n",
  20         //      p->addr, regs->eip, regs->eflags);
  21         //dump_stack();
  22         return 0;
  23 }
  24
  25 /*kprobe post_handler: called after the probed instruction is executed*/
  26 void handler_post(struct kprobe *p, struct pt_regs *regs, unsigned long flags)
  27 {
  28         //printk("post_handler: p->addr=0x%p, eflags=0x%lx\n",
  29         //      p->addr, regs->eflags);
  30 }
  31
  32 /* fault_handler: this is called if an exception is generated for any
  33  * instruction within the pre- or post-handler, or when Kprobes
  34  * single-steps the probed instruction.
  35  */
  36 int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr)
  37 {
  38         //printk("fault_handler: p->addr=0x%p, trap #%dn",
  39         //      p->addr, trapnr);
  40         /* Return 0 because we don't handle the fault. */
  41         return 0;
  42 }
  43
  44 int init_module(void)
  45 {
  46         int ret;
  47         kp.pre_handler = handler_pre;
  48         kp.post_handler = handler_post;
  49         kp.fault_handler = handler_fault;
  50         kp.addr = (kprobe_opcode_t*) kallsyms_lookup_name("ltt_relay_reserve_slot");
  51         /* register the kprobe now */
  52         if (!kp.addr) {
  53                 printk("Couldn't find %s to plant kprobe\n", "ltt_relay_reserve_slot");
  54                 return -1;
  55         }
  56         if ((ret = register_kprobe(&kp) < 0)) {
  57                 printk("register_kprobe failed, returned %d\n", ret);
  58                 return -1;
  59         }
  60         printk("kprobe registered\n");
  61         return 0;
  62 }
  63
  64 void cleanup_module(void)
  65 {
  66         unregister_kprobe(&kp);
  67         printk("kprobe unregistered\n");
  68 }
  69
  70 MODULE_LICENSE("GPL");
  71 MODULE_AUTHOR("Mathieu Desnoyers");
  72 MODULE_DESCRIPTION("Linux Trace Toolkit Test");
  73