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94 lines
1.8 KiB
94 lines
1.8 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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#include <linux/module.h> |
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#include <linux/kthread.h> |
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#include <linux/ftrace.h> |
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void my_direct_func1(void) |
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{ |
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trace_printk("my direct func1\n"); |
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} |
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void my_direct_func2(void) |
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{ |
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trace_printk("my direct func2\n"); |
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} |
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extern void my_tramp1(void *); |
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extern void my_tramp2(void *); |
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static unsigned long my_ip = (unsigned long)schedule; |
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asm ( |
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" .pushsection .text, \"ax\", @progbits\n" |
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" .type my_tramp1, @function\n" |
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" .globl my_tramp1\n" |
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" my_tramp1:" |
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" pushq %rbp\n" |
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" movq %rsp, %rbp\n" |
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" call my_direct_func1\n" |
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" leave\n" |
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" .size my_tramp1, .-my_tramp1\n" |
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" ret\n" |
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" .type my_tramp2, @function\n" |
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" .globl my_tramp2\n" |
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" my_tramp2:" |
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" pushq %rbp\n" |
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" movq %rsp, %rbp\n" |
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" call my_direct_func2\n" |
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" leave\n" |
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" ret\n" |
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" .size my_tramp2, .-my_tramp2\n" |
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" .popsection\n" |
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); |
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static unsigned long my_tramp = (unsigned long)my_tramp1; |
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static unsigned long tramps[2] = { |
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(unsigned long)my_tramp1, |
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(unsigned long)my_tramp2, |
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}; |
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static int simple_thread(void *arg) |
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{ |
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static int t; |
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int ret = 0; |
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while (!kthread_should_stop()) { |
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set_current_state(TASK_INTERRUPTIBLE); |
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schedule_timeout(2 * HZ); |
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if (ret) |
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continue; |
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t ^= 1; |
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ret = modify_ftrace_direct(my_ip, my_tramp, tramps[t]); |
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if (!ret) |
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my_tramp = tramps[t]; |
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WARN_ON_ONCE(ret); |
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} |
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return 0; |
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} |
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static struct task_struct *simple_tsk; |
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static int __init ftrace_direct_init(void) |
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{ |
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int ret; |
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ret = register_ftrace_direct(my_ip, my_tramp); |
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if (!ret) |
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simple_tsk = kthread_run(simple_thread, NULL, "event-sample-fn"); |
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return ret; |
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} |
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static void __exit ftrace_direct_exit(void) |
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{ |
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kthread_stop(simple_tsk); |
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unregister_ftrace_direct(my_ip, my_tramp); |
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} |
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module_init(ftrace_direct_init); |
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module_exit(ftrace_direct_exit); |
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MODULE_AUTHOR("Steven Rostedt"); |
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MODULE_DESCRIPTION("Example use case of using modify_ftrace_direct()"); |
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MODULE_LICENSE("GPL");
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