1 // SPDX-License-Identifier: GPL-2.0-only 2 #include <linux/module.h> 3 4 #include <linux/sched.h> /* for wake_up_process() */ 5 #include <linux/ftrace.h> 6 7 void my_direct_func(struct task_struct *p) 8 { 9 trace_printk("waking up %s-%d\n", p->comm, p->pid); 10 } 11 12 extern void my_tramp(void *); 13 14 asm ( 15 " .pushsection .text, \"ax\", @progbits\n" 16 " .type my_tramp, @function\n" 17 " my_tramp:" 18 " pushq %rbp\n" 19 " movq %rsp, %rbp\n" 20 " pushq %rdi\n" 21 " call my_direct_func\n" 22 " popq %rdi\n" 23 " leave\n" 24 " ret\n" 25 " .size my_tramp, .-my_tramp\n" 26 " .popsection\n" 27 ); 28 29 30 static int __init ftrace_direct_init(void) 31 { 32 return register_ftrace_direct((unsigned long)wake_up_process, 33 (unsigned long)my_tramp); 34 } 35 36 static void __exit ftrace_direct_exit(void) 37 { 38 unregister_ftrace_direct((unsigned long)wake_up_process, 39 (unsigned long)my_tramp); 40 } 41 42 module_init(ftrace_direct_init); 43 module_exit(ftrace_direct_exit); 44 45 MODULE_AUTHOR("Steven Rostedt"); 46 MODULE_DESCRIPTION("Example use case of using register_ftrace_direct()"); 47 MODULE_LICENSE("GPL"); 48