// SPDX-License-Identifier: GPL-2.0-only #include <linux/module.h> #include <linux/sched.h> /* for wake_up_process() */ #include <linux/ftrace.h> void my_direct_func(struct task_struct *p) { trace_printk("waking up %s-%d\n", p->comm, p->pid); } extern void my_tramp(void *); asm ( " .pushsection .text, \"ax\", @progbits\n" " .type my_tramp, @function\n" " .globl my_tramp\n" " my_tramp:" " pushq %rbp\n" " movq %rsp, %rbp\n" " pushq %rdi\n" " call my_direct_func\n" " popq %rdi\n" " leave\n" " ret\n" " .size my_tramp, .-my_tramp\n" " .popsection\n" ); static int __init ftrace_direct_init(void) { return register_ftrace_direct((unsigned long)wake_up_process, (unsigned long)my_tramp); } static void __exit ftrace_direct_exit(void) { unregister_ftrace_direct((unsigned long)wake_up_process, (unsigned long)my_tramp); } module_init(ftrace_direct_init); module_exit(ftrace_direct_exit); MODULE_AUTHOR("Steven Rostedt"); MODULE_DESCRIPTION("Example use case of using register_ftrace_direct()"); MODULE_LICENSE("GPL");