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
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
|
#include <fcntl.h>
#include <linux/magic.h>
#include <mntent.h>
#include <stdio.h>
#include <string.h>
#include <sys/vfs.h>
/* This should be defined before #include "utils.h" */
#define PR_FMT "kernel"
#define PR_DOMAIN DBG_KERNEL
#include "utils/tracefs.h"
#include "utils/utils.h"
#ifndef TRACEFS_MAGIC
#define TRACEFS_MAGIC 0x74726163
#endif
#define PROC_MOUNTS_DIR_PATH "/proc/mounts"
#define TRACEFS_DIR_PATH "/sys/kernel/tracing"
#define OLD_TRACEFS_DIR_PATH "/sys/kernel/debug/tracing"
static char *TRACING_DIR = NULL;
static bool find_tracing_dir(void)
{
FILE *fp;
struct mntent *ent;
struct statfs fs;
if (TRACING_DIR)
return true;
if (!statfs(TRACEFS_DIR_PATH, &fs) && fs.f_type == TRACEFS_MAGIC) {
xasprintf(&TRACING_DIR, "%s", TRACEFS_DIR_PATH);
return true;
}
else if (!statfs(OLD_TRACEFS_DIR_PATH, &fs) && fs.f_type == TRACEFS_MAGIC) {
xasprintf(&TRACING_DIR, "%s", OLD_TRACEFS_DIR_PATH);
return true;
}
fp = setmntent(PROC_MOUNTS_DIR_PATH, "r");
if (fp == NULL)
return false;
while ((ent = getmntent(fp)) != NULL) {
if (!strcmp(ent->mnt_fsname, "tracefs")) {
xasprintf(&TRACING_DIR, "%s", ent->mnt_dir);
break;
}
}
endmntent(fp);
if (!TRACING_DIR) {
pr_dbg2("No tracefs or debugfs found..!\n");
return false;
}
return true;
}
char *get_tracing_file(const char *name)
{
char *file = NULL;
if (!TRACING_DIR && !find_tracing_dir())
return NULL;
xasprintf(&file, "%s/%s", TRACING_DIR, name);
return file;
}
void put_tracing_file(char *file)
{
free(file);
}
int open_tracing_file(const char *name, int flags)
{
char *file;
int fd;
file = get_tracing_file(name);
if (!file) {
pr_dbg("cannot get tracing file: %s: %m\n", name);
return -1;
}
fd = open(file, flags);
if (fd < 0)
pr_dbg("cannot open tracing file: %s: %m\n", name);
put_tracing_file(file);
return fd;
}
ssize_t read_tracing_file(const char *name, char *buf, size_t len)
{
ssize_t ret;
int fd = open_tracing_file(name, O_RDONLY);
if (fd < 0)
return -1;
ret = read(fd, buf, len);
close(fd);
return ret;
}
int __write_tracing_file(int fd, const char *name, const char *val, bool append,
bool correct_sys_prefix)
{
int ret = -1;
ssize_t size = strlen(val);
if (correct_sys_prefix) {
char *newval = (char *)val;
if (!strncmp(val, "sys_", 4))
newval[0] = newval[2] = 'S';
else if (!strncmp(val, "compat_sys_", 11))
newval[7] = newval[9] = 'S';
else
correct_sys_prefix = false;
}
pr_dbg2("%s '%s' to tracing/%s\n", append ? "appending" : "writing", val, name);
if (write(fd, val, size) == size)
ret = 0;
if (correct_sys_prefix) {
char *newval = (char *)val;
if (!strncmp(val, "SyS_", 4))
newval[0] = newval[2] = 's';
else if (!strncmp(val, "compat_SyS_", 11))
newval[7] = newval[9] = 's';
/* write a whitespace to distinguish the previous pattern */
if (write(fd, " ", 1) < 0)
ret = -1;
pr_dbg2("%s '%s' to tracing/%s\n", append ? "appending" : "writing", val, name);
if (write(fd, val, size) == size)
ret = 0;
}
if (ret < 0)
pr_dbg("write '%s' to tracing/%s failed: %m\n", val, name);
return ret;
}
int write_tracing_file(const char *name, const char *val)
{
int ret;
int fd = open_tracing_file(name, O_WRONLY | O_TRUNC);
if (fd < 0)
return -1;
ret = __write_tracing_file(fd, name, val, false, false);
close(fd);
return ret;
}
int append_tracing_file(const char *name, const char *val)
{
int ret;
int fd = open_tracing_file(name, O_WRONLY | O_APPEND);
if (fd < 0)
return -1;
ret = __write_tracing_file(fd, name, val, true, false);
close(fd);
return ret;
}
int set_tracing_pid(int pid)
{
char buf[16];
snprintf(buf, sizeof(buf), "%d", pid);
if (append_tracing_file("set_ftrace_pid", buf) < 0)
return -1;
/* ignore error on old kernel */
append_tracing_file("set_event_pid", buf);
return 0;
}
int set_tracing_clock(char *clock_str)
{
/* set to default clock source if not given */
if (clock_str == NULL)
clock_str = "mono";
return write_tracing_file("trace_clock", clock_str);
}
|