kprobes: switch to kernel_clone()

The old _do_fork() helper is removed in favor of the new kernel_clone() helper.
The latter adheres to naming conventions for kernel internal syscall helpers.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Alexandre Chartre <alexandre.chartre@oracle.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/r/20200819104655.436656-9-christian.brauner@ubuntu.com

samples/kprobes/kprobe_example.c

@@ -2,21 +2,21 @@
 /*
  * 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.
+ * stack trace and selected registers when kernel_clone() is called.
  *
  * For more information on theory of operation of kprobes, see
  * Documentation/staging/kprobes.rst
  *
  * You will see the trace data in /var/log/messages and on the console
- * whenever _do_fork() is invoked to create a new process.
+ * whenever kernel_clone() is invoked to create a new process.
  */
 
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/kprobes.h>
 
 #define MAX_SYMBOL_LEN	64
-static char symbol[MAX_SYMBOL_LEN] = "_do_fork";
+static char symbol[MAX_SYMBOL_LEN] = "kernel_clone";
 module_param_string(symbol, symbol, sizeof(symbol), 0644);
 
 /* For each probe you need to allocate a kprobe structure */