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
16static char tracing_mnt[PATH_MAX]  = "/sys/kernel/debug";
17static char tracing_path[PATH_MAX]        = "/sys/kernel/debug/tracing";
18static char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events";
19
20static 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
29static 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
42static 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
55const 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
68void tracing_path_set(const char *mntpt)
69{
70	__tracing_path_set("tracing/", mntpt);
71}
72
73char *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
83void put_tracing_file(char *file)
84{
85	free(file);
86}
87
88char *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
98void put_events_file(char *file)
99{
100	free(file);
101}
102
103DIR *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
116int 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}
168