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 " my_tramp:" 17 " pushq %rbp\n" 18 " movq %rsp, %rbp\n" 19 " pushq %rdi\n" 20 " call my_direct_func\n" 21 " popq %rdi\n" 22 " leave\n" 23 " ret\n" 24 " .popsection\n" 25 ); 26 27 28 static int __init ftrace_direct_init(void) 29 { 30 return register_ftrace_direct((unsigned long)wake_up_process, 31 (unsigned long)my_tramp); 32 } 33 34 static void __exit ftrace_direct_exit(void) 35 { 36 unregister_ftrace_direct((unsigned long)wake_up_process, 37 (unsigned long)my_tramp); 38 } 39 40 module_init(ftrace_direct_init); 41 module_exit(ftrace_direct_exit); 42 43 MODULE_AUTHOR("Steven Rostedt"); 44 MODULE_DESCRIPTION("Example use case of using register_ftrace_direct()"); 45 MODULE_LICENSE("GPL"); 46