1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
|
/* Copyright (c) 2014, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <linux/perf_event.h>
#include <linux/types.h>
#include <linux/tracepoint.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/preempt.h>
#include <linux/stat.h>
#include <asm/uaccess.h>
#define CREATE_TRACE_POINTS
#include "perf_trace_user.h"
#undef TRACE_SYSTEM
#define TRACE_SYSTEM perf_trace_counters
#define TRACE_USER_MAX_BUF_SIZE 100
static ssize_t perf_trace_write(struct file *file,
const char __user *user_string_in,
size_t len, loff_t *ppos)
{
u32 cnten_val;
int rc;
char buf[TRACE_USER_MAX_BUF_SIZE + 1];
ssize_t length;
if (len == 0)
return 0;
length = len > TRACE_USER_MAX_BUF_SIZE ? TRACE_USER_MAX_BUF_SIZE : len;
rc = copy_from_user(buf, user_string_in, length);
if (rc) {
pr_err("%s copy_from_user failed, rc=%d\n", __func__, rc);
return length;
}
/* Remove any trailing newline and make sure string is terminated */
if (buf[length - 1] == '\n')
buf[length - 1] = '\0';
else
buf[length] = '\0';
/*
* Disable preemption to ensure that all the performance counter
* accesses happen on the same cpu
*/
preempt_disable();
/* stop counters, call the trace function, restart them */
asm volatile("mrs %0, pmcntenset_el0" : "=r" (cnten_val));
/* Disable all the counters that were enabled */
asm volatile("msr pmcntenclr_el0, %0" : : "r" (cnten_val));
trace_perf_trace_user(buf, cnten_val);
/* Enable all the counters that were disabled */
asm volatile("msr pmcntenset_el0, %0" : : "r" (cnten_val));
preempt_enable();
return length;
}
static const struct file_operations perf_trace_fops = {
.write = perf_trace_write
};
static int __init init_perf_trace(void)
{
struct dentry *dir;
struct dentry *file;
unsigned int value = 1;
dir = perf_create_debug_dir();
if (!dir)
return -ENOMEM;
file = debugfs_create_file("trace_marker", S_IWUSR | S_IWGRP, dir,
&value, &perf_trace_fops);
if (!file)
return -ENOMEM;
return 0;
}
late_initcall(init_perf_trace);
|
