projects / thirdparty / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| ae0cc3b7 SRV |
1 | // SPDX-License-Identifier: GPL-2.0-only |
| 2 | #include <linux/module.h> | |
| 3 | #include <linux/kthread.h> | |
| 4 | #include <linux/ftrace.h> | |
| 5 | ||
| 6 | void my_direct_func1(void) | |
| 7 | { | |
| 8 | trace_printk("my direct func1\n"); | |
| 9 | } | |
| 10 | ||
| 11 | void my_direct_func2(void) | |
| 12 | { | |
| 13 | trace_printk("my direct func2\n"); | |
| 14 | } | |
| 15 | ||
| 16 | extern void my_tramp1(void *); | |
| 17 | extern void my_tramp2(void *); | |
| 18 | ||
| 19 | static unsigned long my_ip = (unsigned long)schedule; | |
| 20 | ||
| 21 | asm ( | |
| 22 | " .pushsection .text, \"ax\", @progbits\n" | |
| 9d907f1a | 23 | " .type my_tramp1, @function\n" |
| ae0cc3b7 SRV |
24 | " my_tramp1:" |
| 25 | " pushq %rbp\n" | |
| 26 | " movq %rsp, %rbp\n" | |
| 27 | " call my_direct_func1\n" | |
| 28 | " leave\n" | |
| 9d907f1a | 29 | " .size my_tramp1, .-my_tramp1\n" |
| ae0cc3b7 | 30 | " ret\n" |
| 9d907f1a | 31 | " .type my_tramp2, @function\n" |
| ae0cc3b7 SRV |
32 | " my_tramp2:" |
| 33 | " pushq %rbp\n" | |
| 34 | " movq %rsp, %rbp\n" | |
| 35 | " call my_direct_func2\n" | |
| 36 | " leave\n" | |
| 37 | " ret\n" | |
| 9d907f1a | 38 | " .size my_tramp2, .-my_tramp2\n" |
| ae0cc3b7 SRV |
39 | " .popsection\n" |
| 40 | ); | |
| 41 | ||
| 42 | static unsigned long my_tramp = (unsigned long)my_tramp1; | |
| 43 | static unsigned long tramps[2] = { | |
| 44 | (unsigned long)my_tramp1, | |
| 45 | (unsigned long)my_tramp2, | |
| 46 | }; | |
| 47 | ||
| 48 | static int simple_thread(void *arg) | |
| 49 | { | |
| 50 | static int t; | |
| 51 | int ret = 0; | |
| 52 | ||
| 53 | while (!kthread_should_stop()) { | |
| 54 | set_current_state(TASK_INTERRUPTIBLE); | |
| 55 | schedule_timeout(2 * HZ); | |
| 56 | ||
| 57 | if (ret) | |
| 58 | continue; | |
| 59 | t ^= 1; | |
| 60 | ret = modify_ftrace_direct(my_ip, my_tramp, tramps[t]); | |
| 61 | if (!ret) | |
| 62 | my_tramp = tramps[t]; | |
| 63 | WARN_ON_ONCE(ret); | |
| 64 | } | |
| 65 | ||
| 66 | return 0; | |
| 67 | } | |
| 68 | ||
| 69 | static struct task_struct *simple_tsk; | |
| 70 | ||
| 71 | static int __init ftrace_direct_init(void) | |
| 72 | { | |
| 73 | int ret; | |
| 74 | ||
| 75 | ret = register_ftrace_direct(my_ip, my_tramp); | |
| 76 | if (!ret) | |
| 77 | simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn"); | |
| 78 | return ret; | |
| 79 | } | |
| 80 | ||
| 81 | static void __exit ftrace_direct_exit(void) | |
| 82 | { | |
| 83 | kthread_stop(simple_tsk); | |
| 84 | unregister_ftrace_direct(my_ip, my_tramp); | |
| 85 | } | |
| 86 | ||
| 87 | module_init(ftrace_direct_init); | |
| 88 | module_exit(ftrace_direct_exit); | |
| 89 | ||
| 90 | MODULE_AUTHOR("Steven Rostedt"); | |
| 91 | MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct()"); | |
| 92 | MODULE_LICENSE("GPL"); |