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_events__scandir_alphasort(struct dirent ***namelist) 117 { 118 char *path = get_tracing_file("events"); 119 int ret; 120 121 if (!path) { 122 *namelist = NULL; 123 return 0; 124 } 125 126 ret = scandir(path, namelist, NULL, alphasort); 127 put_events_file(path); 128 129 return ret; 130 } 131 132 int tracing_path__strerror_open_tp(int err, char *buf, size_t size, 133 const char *sys, const char *name) 134 { 135 char sbuf[128]; 136 char filename[PATH_MAX]; 137 138 snprintf(filename, PATH_MAX, "%s/%s", sys, name ?: "*"); 139 140 switch (err) { 141 case ENOENT: 142 /* 143 * We will get here if we can't find the tracepoint, but one of 144 * debugfs or tracefs is configured, which means you probably 145 * want some tracepoint which wasn't compiled in your kernel. 146 * - jirka 147 */ 148 if (debugfs__configured() || tracefs__configured()) { 149 /* sdt markers */ 150 if (!strncmp(filename, "sdt_", 4)) { 151 snprintf(buf, size, 152 "Error:\tFile %s/%s not found.\n" 153 "Hint:\tSDT event cannot be directly recorded on.\n" 154 "\tPlease first use 'perf probe %s:%s' before recording it.\n", 155 tracing_events_path, filename, sys, name); 156 } else { 157 snprintf(buf, size, 158 "Error:\tFile %s/%s not found.\n" 159 "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n", 160 tracing_events_path, filename); 161 } 162 break; 163 } 164 snprintf(buf, size, "%s", 165 "Error:\tUnable to find debugfs/tracefs\n" 166 "Hint:\tWas your kernel compiled with debugfs/tracefs support?\n" 167 "Hint:\tIs the debugfs/tracefs filesystem mounted?\n" 168 "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'"); 169 break; 170 case EACCES: { 171 snprintf(buf, size, 172 "Error:\tNo permissions to read %s/%s\n" 173 "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n", 174 tracing_events_path, filename, tracing_path_mount()); 175 } 176 break; 177 default: 178 snprintf(buf, size, "%s", str_error_r(err, sbuf, sizeof(sbuf))); 179 break; 180 } 181 182 return 0; 183 } 184