Kprobes: move kprobe examples to samples/

[pandora-kernel.git] / samples / kprobes / jprobe_example.c

diff --git a/samples/kprobes/jprobe_example.c b/samples/kprobes/jprobe_example.c
new file mode 100644 (file)
index 0000000..b754135
--- /dev/null
+++ b/samples/kprobes/jprobe_example.c
@@ -0,0 +1,68 @@
+/*
+ * Here's a sample kernel module showing the use of jprobes to dump
+ * the arguments of do_fork().
+ *
+ * For more information on theory of operation of jprobes, see
+ * Documentation/kprobes.txt
+ *
+ * Build and insert the kernel module as done in the kprobe example.
+ * You will see the trace data in /var/log/messages and on the
+ * console whenever do_fork() is invoked to create a new process.
+ * (Some messages may be suppressed if syslogd is configured to
+ * eliminate duplicate messages.)
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/kprobes.h>
+
+/*
+ * Jumper probe for do_fork.
+ * Mirror principle enables access to arguments of the probed routine
+ * from the probe handler.
+ */
+
+/* Proxy routine having the same arguments as actual do_fork() routine */
+static long jdo_fork(unsigned long clone_flags, unsigned long stack_start,
+             struct pt_regs *regs, unsigned long stack_size,
+             int __user *parent_tidptr, int __user *child_tidptr)
+{
+       printk(KERN_INFO "jprobe: clone_flags = 0x%lx, stack_size = 0x%lx,"
+                       " regs = 0x%p\n",
+              clone_flags, stack_size, regs);
+
+       /* Always end with a call to jprobe_return(). */
+       jprobe_return();
+       return 0;
+}
+
+static struct jprobe my_jprobe = {
+       .entry                  = jdo_fork,
+       .kp = {
+               .symbol_name    = "do_fork",
+       },
+};
+
+static int __init jprobe_init(void)
+{
+       int ret;
+
+       ret = register_jprobe(&my_jprobe);
+       if (ret < 0) {
+               printk(KERN_INFO "register_jprobe failed, returned %d\n", ret);
+               return -1;
+       }
+       printk(KERN_INFO "Planted jprobe at %p, handler addr %p\n",
+              my_jprobe.kp.addr, my_jprobe.entry);
+       return 0;
+}
+
+static void __exit jprobe_exit(void)
+{
+       unregister_jprobe(&my_jprobe);
+       printk(KERN_INFO "jprobe at %p unregistered\n", my_jprobe.kp.addr);
+}
+
+module_init(jprobe_init)
+module_exit(jprobe_exit)
+MODULE_LICENSE("GPL");