Merge tag 'for-5.2/io_uring-20190507' of git://git.kernel.dk/linux-block
[sfrench/cifs-2.6.git] / tools / lib / api / fs / tracing_path.c
1 // SPDX-License-Identifier: GPL-2.0
2 #ifndef _GNU_SOURCE
3 # define _GNU_SOURCE
4 #endif
5
6 #include <stdio.h>
7 #include <stdlib.h>
8 #include <string.h>
9 #include <linux/string.h>
10 #include <errno.h>
11 #include <unistd.h>
12 #include "fs.h"
13
14 #include "tracing_path.h"
15
16 static char tracing_mnt[PATH_MAX]  = "/sys/kernel/debug";
17 static char tracing_path[PATH_MAX]        = "/sys/kernel/debug/tracing";
18 static char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events";
19
20 static void __tracing_path_set(const char *tracing, const char *mountpoint)
21 {
22         snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint);
23         snprintf(tracing_path, sizeof(tracing_path), "%s/%s",
24                  mountpoint, tracing);
25         snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s",
26                  mountpoint, tracing, "events");
27 }
28
29 static const char *tracing_path_tracefs_mount(void)
30 {
31         const char *mnt;
32
33         mnt = tracefs__mount();
34         if (!mnt)
35                 return NULL;
36
37         __tracing_path_set("", mnt);
38
39         return tracing_path;
40 }
41
42 static const char *tracing_path_debugfs_mount(void)
43 {
44         const char *mnt;
45
46         mnt = debugfs__mount();
47         if (!mnt)
48                 return NULL;
49
50         __tracing_path_set("tracing/", mnt);
51
52         return tracing_path;
53 }
54
55 const char *tracing_path_mount(void)
56 {
57         const char *mnt;
58
59         mnt = tracing_path_tracefs_mount();
60         if (mnt)
61                 return mnt;
62
63         mnt = tracing_path_debugfs_mount();
64
65         return mnt;
66 }
67
68 void tracing_path_set(const char *mntpt)
69 {
70         __tracing_path_set("tracing/", mntpt);
71 }
72
73 char *get_tracing_file(const char *name)
74 {
75         char *file;
76
77         if (asprintf(&file, "%s/%s", tracing_path_mount(), name) < 0)
78                 return NULL;
79
80         return file;
81 }
82
83 void put_tracing_file(char *file)
84 {
85         free(file);
86 }
87
88 char *get_events_file(const char *name)
89 {
90         char *file;
91
92         if (asprintf(&file, "%s/events/%s", tracing_path_mount(), name) < 0)
93                 return NULL;
94
95         return file;
96 }
97
98 void put_events_file(char *file)
99 {
100         free(file);
101 }
102
103 DIR *tracing_events__opendir(void)
104 {
105         DIR *dir = NULL;
106         char *path = get_tracing_file("events");
107
108         if (path) {
109                 dir = opendir(path);
110                 put_events_file(path);
111         }
112
113         return dir;
114 }
115
116 int tracing_path__strerror_open_tp(int err, char *buf, size_t size,
117                                    const char *sys, const char *name)
118 {
119         char sbuf[128];
120         char filename[PATH_MAX];
121
122         snprintf(filename, PATH_MAX, "%s/%s", sys, name ?: "*");
123
124         switch (err) {
125         case ENOENT:
126                 /*
127                  * We will get here if we can't find the tracepoint, but one of
128                  * debugfs or tracefs is configured, which means you probably
129                  * want some tracepoint which wasn't compiled in your kernel.
130                  * - jirka
131                  */
132                 if (debugfs__configured() || tracefs__configured()) {
133                         /* sdt markers */
134                         if (!strncmp(filename, "sdt_", 4)) {
135                                 snprintf(buf, size,
136                                         "Error:\tFile %s/%s not found.\n"
137                                         "Hint:\tSDT event cannot be directly recorded on.\n"
138                                         "\tPlease first use 'perf probe %s:%s' before recording it.\n",
139                                         tracing_events_path, filename, sys, name);
140                         } else {
141                                 snprintf(buf, size,
142                                          "Error:\tFile %s/%s not found.\n"
143                                          "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",
144                                          tracing_events_path, filename);
145                         }
146                         break;
147                 }
148                 snprintf(buf, size, "%s",
149                          "Error:\tUnable to find debugfs/tracefs\n"
150                          "Hint:\tWas your kernel compiled with debugfs/tracefs support?\n"
151                          "Hint:\tIs the debugfs/tracefs filesystem mounted?\n"
152                          "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
153                 break;
154         case EACCES: {
155                 snprintf(buf, size,
156                          "Error:\tNo permissions to read %s/%s\n"
157                          "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
158                          tracing_events_path, filename, tracing_path_mount());
159         }
160                 break;
161         default:
162                 snprintf(buf, size, "%s", str_error_r(err, sbuf, sizeof(sbuf)));
163                 break;
164         }
165
166         return 0;
167 }