cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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sample-trace-array.c (3581B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2#include <linux/module.h>
      3#include <linux/kthread.h>
      4#include <linux/trace.h>
      5#include <linux/trace_events.h>
      6#include <linux/timer.h>
      7#include <linux/err.h>
      8#include <linux/jiffies.h>
      9#include <linux/workqueue.h>
     10
     11/*
     12 * Any file that uses trace points, must include the header.
     13 * But only one file, must include the header by defining
     14 * CREATE_TRACE_POINTS first.  This will make the C code that
     15 * creates the handles for the trace points.
     16 */
     17#define CREATE_TRACE_POINTS
     18#include "sample-trace-array.h"
     19
     20struct trace_array *tr;
     21static void mytimer_handler(struct timer_list *unused);
     22static struct task_struct *simple_tsk;
     23
     24static void trace_work_fn(struct work_struct *work)
     25{
     26	/*
     27	 * Disable tracing for event "sample_event".
     28	 */
     29	trace_array_set_clr_event(tr, "sample-subsystem", "sample_event",
     30			false);
     31}
     32static DECLARE_WORK(trace_work, trace_work_fn);
     33
     34/*
     35 * mytimer: Timer setup to disable tracing for event "sample_event". This
     36 * timer is only for the purposes of the sample module to demonstrate access of
     37 * Ftrace instances from within kernel.
     38 */
     39static DEFINE_TIMER(mytimer, mytimer_handler);
     40
     41static void mytimer_handler(struct timer_list *unused)
     42{
     43	schedule_work(&trace_work);
     44}
     45
     46static void simple_thread_func(int count)
     47{
     48	set_current_state(TASK_INTERRUPTIBLE);
     49	schedule_timeout(HZ);
     50
     51	/*
     52	 * Printing count value using trace_array_printk() - trace_printk()
     53	 * equivalent for the instance buffers.
     54	 */
     55	trace_array_printk(tr, _THIS_IP_, "trace_array_printk: count=%d\n",
     56			count);
     57	/*
     58	 * Tracepoint for event "sample_event". This will print the
     59	 * current value of count and current jiffies.
     60	 */
     61	trace_sample_event(count, jiffies);
     62}
     63
     64static int simple_thread(void *arg)
     65{
     66	int count = 0;
     67	unsigned long delay = msecs_to_jiffies(5000);
     68
     69	/*
     70	 * Enable tracing for "sample_event".
     71	 */
     72	trace_array_set_clr_event(tr, "sample-subsystem", "sample_event", true);
     73
     74	/*
     75	 * Adding timer - mytimer. This timer will disable tracing after
     76	 * delay seconds.
     77	 *
     78	 */
     79	add_timer(&mytimer);
     80	mod_timer(&mytimer, jiffies+delay);
     81
     82	while (!kthread_should_stop())
     83		simple_thread_func(count++);
     84
     85	del_timer(&mytimer);
     86	cancel_work_sync(&trace_work);
     87
     88	/*
     89	 * trace_array_put() decrements the reference counter associated with
     90	 * the trace array - "tr". We are done using the trace array, hence
     91	 * decrement the reference counter so that it can be destroyed using
     92	 * trace_array_destroy().
     93	 */
     94	trace_array_put(tr);
     95
     96	return 0;
     97}
     98
     99static int __init sample_trace_array_init(void)
    100{
    101	/*
    102	 * Return a pointer to the trace array with name "sample-instance" if it
    103	 * exists, else create a new trace array.
    104	 *
    105	 * NOTE: This function increments the reference counter
    106	 * associated with the trace array - "tr".
    107	 */
    108	tr = trace_array_get_by_name("sample-instance");
    109
    110	if (!tr)
    111		return -1;
    112	/*
    113	 * If context specific per-cpu buffers havent already been allocated.
    114	 */
    115	trace_printk_init_buffers();
    116
    117	simple_tsk = kthread_run(simple_thread, NULL, "sample-instance");
    118	if (IS_ERR(simple_tsk)) {
    119		trace_array_put(tr);
    120		trace_array_destroy(tr);
    121		return -1;
    122	}
    123
    124	return 0;
    125}
    126
    127static void __exit sample_trace_array_exit(void)
    128{
    129	kthread_stop(simple_tsk);
    130
    131	/*
    132	 * We are unloading our module and no longer require the trace array.
    133	 * Remove/destroy "tr" using trace_array_destroy()
    134	 */
    135	trace_array_destroy(tr);
    136}
    137
    138module_init(sample_trace_array_init);
    139module_exit(sample_trace_array_exit);
    140
    141MODULE_AUTHOR("Divya Indi");
    142MODULE_DESCRIPTION("Sample module for kernel access to Ftrace instances");
    143MODULE_LICENSE("GPL");