1 #define _GNU_SOURCE
2 #include <errno.h>
3 #include <stdio.h>
4 #include <stdlib.h>
5 #include <string.h>
6 #include <unistd.h>
7 #include <stdbool.h>
8 #include <sys/vfs.h>
9 #include <sys/types.h>
10 #include <sys/stat.h>
11 #include <sys/mount.h>
12 #include <linux/kernel.h>
13
14 #include "debugfs.h"
15
16 #ifndef DEBUGFS_DEFAULT_PATH
17 #define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug"
18 #endif
19
20 char debugfs_mountpoint[PATH_MAX + 1] = DEBUGFS_DEFAULT_PATH;
21
22 static const char * const debugfs_known_mountpoints[] = {
23 DEBUGFS_DEFAULT_PATH,
24 "/debug",
25 0,
26 };
27
28 static bool debugfs_found;
29
debugfs_configured(void)30 bool debugfs_configured(void)
31 {
32 return debugfs_find_mountpoint() != NULL;
33 }
34
35 /* find the path to the mounted debugfs */
debugfs_find_mountpoint(void)36 const char *debugfs_find_mountpoint(void)
37 {
38 const char *ret;
39
40 if (debugfs_found)
41 return (const char *)debugfs_mountpoint;
42
43 ret = find_mountpoint("debugfs", (long) DEBUGFS_MAGIC,
44 debugfs_mountpoint, PATH_MAX + 1,
45 debugfs_known_mountpoints);
46 if (ret)
47 debugfs_found = true;
48
49 return ret;
50 }
51
52 /* mount the debugfs somewhere if it's not mounted */
debugfs_mount(const char * mountpoint)53 char *debugfs_mount(const char *mountpoint)
54 {
55 /* see if it's already mounted */
56 if (debugfs_find_mountpoint())
57 goto out;
58
59 /* if not mounted and no argument */
60 if (mountpoint == NULL) {
61 /* see if environment variable set */
62 mountpoint = getenv(PERF_DEBUGFS_ENVIRONMENT);
63 /* if no environment variable, use default */
64 if (mountpoint == NULL)
65 mountpoint = DEBUGFS_DEFAULT_PATH;
66 }
67
68 if (mount(NULL, mountpoint, "debugfs", 0, NULL) < 0)
69 return NULL;
70
71 /* save the mountpoint */
72 debugfs_found = true;
73 strncpy(debugfs_mountpoint, mountpoint, sizeof(debugfs_mountpoint));
74 out:
75 return debugfs_mountpoint;
76 }
77
debugfs__strerror_open(int err,char * buf,size_t size,const char * filename)78 int debugfs__strerror_open(int err, char *buf, size_t size, const char *filename)
79 {
80 char sbuf[128];
81
82 switch (err) {
83 case ENOENT:
84 if (debugfs_found) {
85 snprintf(buf, size,
86 "Error:\tFile %s/%s not found.\n"
87 "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n",
88 debugfs_mountpoint, filename);
89 break;
90 }
91 snprintf(buf, size, "%s",
92 "Error:\tUnable to find debugfs\n"
93 "Hint:\tWas your kernel compiled with debugfs support?\n"
94 "Hint:\tIs the debugfs filesystem mounted?\n"
95 "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'");
96 break;
97 case EACCES:
98 snprintf(buf, size,
99 "Error:\tNo permissions to read %s/%s\n"
100 "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n",
101 debugfs_mountpoint, filename, debugfs_mountpoint);
102 break;
103 default:
104 snprintf(buf, size, "%s", strerror_r(err, sbuf, sizeof(sbuf)));
105 break;
106 }
107
108 return 0;
109 }
110
debugfs__strerror_open_tp(int err,char * buf,size_t size,const char * sys,const char * name)111 int debugfs__strerror_open_tp(int err, char *buf, size_t size, const char *sys, const char *name)
112 {
113 char path[PATH_MAX];
114
115 snprintf(path, PATH_MAX, "tracing/events/%s/%s", sys, name ?: "*");
116
117 return debugfs__strerror_open(err, buf, size, path);
118 }
119