/*
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* Here's a sample kernel module showing the use of jprobes to dump
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* the arguments of _do_fork().
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*
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* For more information on theory of operation of jprobes, see
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* Documentation/kprobes.txt
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*
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* Build and insert the kernel module as done in the kprobe example.
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* You will see the trace data in /var/log/messages and on the
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* console whenever _do_fork() is invoked to create a new process.
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* (Some messages may be suppressed if syslogd is configured to
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* eliminate duplicate messages.)
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/kprobes.h>
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/*
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* Jumper probe for _do_fork.
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* Mirror principle enables access to arguments of the probed routine
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* from the probe handler.
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*/
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/* Proxy routine having the same arguments as actual _do_fork() routine */
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static long j_do_fork(unsigned long clone_flags, unsigned long stack_start,
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unsigned long stack_size, int __user *parent_tidptr,
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int __user *child_tidptr, unsigned long tls)
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{
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pr_info("jprobe: clone_flags = 0x%lx, stack_start = 0x%lx "
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"stack_size = 0x%lx\n", clone_flags, stack_start, stack_size);
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/* Always end with a call to jprobe_return(). */
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jprobe_return();
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return 0;
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}
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static struct jprobe my_jprobe = {
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.entry = j_do_fork,
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.kp = {
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.symbol_name = "_do_fork",
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},
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};
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static int __init jprobe_init(void)
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{
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int ret;
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ret = register_jprobe(&my_jprobe);
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if (ret < 0) {
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pr_err("register_jprobe failed, returned %d\n", ret);
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return -1;
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}
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pr_info("Planted jprobe at %p, handler addr %p\n",
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my_jprobe.kp.addr, my_jprobe.entry);
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return 0;
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}
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static void __exit jprobe_exit(void)
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{
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unregister_jprobe(&my_jprobe);
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pr_info("jprobe at %p unregistered\n", my_jprobe.kp.addr);
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}
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module_init(jprobe_init)
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module_exit(jprobe_exit)
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MODULE_LICENSE("GPL");
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