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 extern void my_direct_func(struct task_struct *p); 8 my_direct_func(struct task_struct * p)9void my_direct_func(struct task_struct *p) 10 { 11 trace_printk("waking up %s-%d\n", p->comm, p->pid); 12 } 13 14 extern void my_tramp(void *); 15 16 asm ( 17 " .pushsection .text, \"ax\", @progbits\n" 18 " .type my_tramp, @function\n" 19 " .globl my_tramp\n" 20 " my_tramp:" 21 " pushq %rbp\n" 22 " movq %rsp, %rbp\n" 23 " pushq %rdi\n" 24 " call my_direct_func\n" 25 " popq %rdi\n" 26 " leave\n" 27 ASM_RET 28 " .size my_tramp, .-my_tramp\n" 29 " .popsection\n" 30 ); 31 32 ftrace_direct_init(void)33static int __init ftrace_direct_init(void) 34 { 35 return register_ftrace_direct((unsigned long)wake_up_process, 36 (unsigned long)my_tramp); 37 } 38 ftrace_direct_exit(void)39static void __exit ftrace_direct_exit(void) 40 { 41 unregister_ftrace_direct((unsigned long)wake_up_process, 42 (unsigned long)my_tramp); 43 } 44 45 module_init(ftrace_direct_init); 46 module_exit(ftrace_direct_exit); 47 48 MODULE_AUTHOR("Steven Rostedt"); 49 MODULE_DESCRIPTION("Example use case of using register_ftrace_direct()"); 50 MODULE_LICENSE("GPL"); 51