92 lines
2.4 KiB
C
92 lines
2.4 KiB
C
|
/*
|
||
|
|
* NOTE: This example is works on x86 and powerpc.
|
||
|
|
* Here's a sample kernel module showing the use of kprobes to dump a
|
||
|
|
* stack trace and selected registers when do_fork() is called.
|
||
|
|
*
|
||
|
|
* For more information on theory of operation of kprobes, see
|
||
|
|
* Documentation/kprobes.txt
|
||
|
|
*
|
||
|
|
* You will see the trace data in /var/log/messages and on the console
|
||
|
|
* whenever do_fork() is invoked to create a new process.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/kernel.h>
|
||
|
|
#include <linux/module.h>
|
||
|
|
#include <linux/kprobes.h>
|
||
|
|
|
||
|
|
/* For each probe you need to allocate a kprobe structure */
|
||
|
|
static struct kprobe kp = {
|
||
|
|
.symbol_name = "do_fork",
|
||
|
|
};
|
||
|
|
|
||
|
|
/* kprobe pre_handler: called just before the probed instruction is executed */
|
||
|
|
static int handler_pre(struct kprobe *p, struct pt_regs *regs)
|
||
|
|
{
|
||
|
|
#ifdef CONFIG_X86
|
||
|
|
printk(KERN_INFO "pre_handler: p->addr = 0x%p, ip = %lx,"
|
||
|
|
" flags = 0x%lx\n",
|
||
|
|
p->addr, regs->ip, regs->flags);
|
||
|
|
#endif
|
||
|
|
#ifdef CONFIG_PPC
|
||
|
|
printk(KERN_INFO "pre_handler: p->addr = 0x%p, nip = 0x%lx,"
|
||
|
|
" msr = 0x%lx\n",
|
||
|
|
p->addr, regs->nip, regs->msr);
|
||
|
|
#endif
|
||
|
|
|
||
|
|
/* A dump_stack() here will give a stack backtrace */
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* kprobe post_handler: called after the probed instruction is executed */
|
||
|
|
static void handler_post(struct kprobe *p, struct pt_regs *regs,
|
||
|
|
unsigned long flags)
|
||
|
|
{
|
||
|
|
#ifdef CONFIG_X86
|
||
|
|
printk(KERN_INFO "post_handler: p->addr = 0x%p, flags = 0x%lx\n",
|
||
|
|
p->addr, regs->flags);
|
||
|
|
#endif
|
||
|
|
#ifdef CONFIG_PPC
|
||
|
|
printk(KERN_INFO "post_handler: p->addr = 0x%p, msr = 0x%lx\n",
|
||
|
|
p->addr, regs->msr);
|
||
|
|
#endif
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* fault_handler: this is called if an exception is generated for any
|
||
|
|
* instruction within the pre- or post-handler, or when Kprobes
|
||
|
|
* single-steps the probed instruction.
|
||
|
|
*/
|
||
|
|
static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr)
|
||
|
|
{
|
||
|
|
printk(KERN_INFO "fault_handler: p->addr = 0x%p, trap #%dn",
|
||
|
|
p->addr, trapnr);
|
||
|
|
/* Return 0 because we don't handle the fault. */
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int __init kprobe_init(void)
|
||
|
|
{
|
||
|
|
int ret;
|
||
|
|
kp.pre_handler = handler_pre;
|
||
|
|
kp.post_handler = handler_post;
|
||
|
|
kp.fault_handler = handler_fault;
|
||
|
|
|
||
|
|
ret = register_kprobe(&kp);
|
||
|
|
if (ret < 0) {
|
||
|
|
printk(KERN_INFO "register_kprobe failed, returned %d\n", ret);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
printk(KERN_INFO "Planted kprobe at %p\n", kp.addr);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static void __exit kprobe_exit(void)
|
||
|
|
{
|
||
|
|
unregister_kprobe(&kp);
|
||
|
|
printk(KERN_INFO "kprobe at %p unregistered\n", kp.addr);
|
||
|
|
}
|
||
|
|
|
||
|
|
module_init(kprobe_init)
|
||
|
|
module_exit(kprobe_exit)
|
||
|
|
MODULE_LICENSE("GPL");
|