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 char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events"; 19 20 21 static void __tracing_path_set(const char *tracing, const char *mountpoint) 22 { 23 snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint); 24 snprintf(tracing_path, sizeof(tracing_path), "%s/%s", 25 mountpoint, tracing); 26 snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s", 27 mountpoint, tracing, "events"); 28 } 29 30 static const char *tracing_path_tracefs_mount(void) 31 { 32 const char *mnt; 33 34 mnt = tracefs__mount(); 35 if (!mnt) 36 return NULL; 37 38 __tracing_path_set("", mnt); 39 40 return mnt; 41 } 42 43 static const char *tracing_path_debugfs_mount(void) 44 { 45 const char *mnt; 46 47 mnt = debugfs__mount(); 48 if (!mnt) 49 return NULL; 50 51 __tracing_path_set("tracing/", mnt); 52 53 return mnt; 54 } 55 56 const char *tracing_path_mount(void) 57 { 58 const char *mnt; 59 60 mnt = tracing_path_tracefs_mount(); 61 if (mnt) 62 return mnt; 63 64 mnt = tracing_path_debugfs_mount(); 65 66 return mnt; 67 } 68 69 void tracing_path_set(const char *mntpt) 70 { 71 __tracing_path_set("tracing/", mntpt); 72 } 73 74 char *get_tracing_file(const char *name) 75 { 76 char *file; 77 78 if (asprintf(&file, "%s/%s", tracing_path_mount(), name) < 0) 79 return NULL; 80 81 return file; 82 } 83 84 void put_tracing_file(char *file) 85 { 86 free(file); 87 } 88 89 char *get_events_file(const char *name) 90 { 91 char *file; 92 93 if (asprintf(&file, "%s/events/%s", tracing_path_mount(), name) < 0) 94 return NULL; 95 96 return file; 97 } 98 99 void put_events_file(char *file) 100 { 101 free(file); 102 } 103 104 DIR *tracing_events__opendir(void) 105 { 106 DIR *dir = NULL; 107 char *path = get_tracing_file("events"); 108 109 if (path) { 110 dir = opendir(path); 111 put_events_file(path); 112 } 113 114 return dir; 115 } 116 117 int tracing_path__strerror_open_tp(int err, char *buf, size_t size, 118 const char *sys, const char *name) 119 { 120 char sbuf[128]; 121 char filename[PATH_MAX]; 122 123 snprintf(filename, PATH_MAX, "%s/%s", sys, name ?: "*"); 124 125 switch (err) { 126 case ENOENT: 127 /* 128 * We will get here if we can't find the tracepoint, but one of 129 * debugfs or tracefs is configured, which means you probably 130 * want some tracepoint which wasn't compiled in your kernel. 131 * - jirka 132 */ 133 if (debugfs__configured() || tracefs__configured()) { 134 /* sdt markers */ 135 if (!strncmp(filename, "sdt_", 4)) { 136 snprintf(buf, size, 137 "Error:\tFile %s/%s not found.\n" 138 "Hint:\tSDT event cannot be directly recorded on.\n" 139 "\tPlease first use 'perf probe %s:%s' before recording it.\n", 140 tracing_events_path, filename, sys, name); 141 } else { 142 snprintf(buf, size, 143 "Error:\tFile %s/%s not found.\n" 144 "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n", 145 tracing_events_path, filename); 146 } 147 break; 148 } 149 snprintf(buf, size, "%s", 150 "Error:\tUnable to find debugfs/tracefs\n" 151 "Hint:\tWas your kernel compiled with debugfs/tracefs support?\n" 152 "Hint:\tIs the debugfs/tracefs filesystem mounted?\n" 153 "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'"); 154 break; 155 case EACCES: { 156 snprintf(buf, size, 157 "Error:\tNo permissions to read %s/%s\n" 158 "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n", 159 tracing_events_path, filename, tracing_path_mount()); 160 } 161 break; 162 default: 163 snprintf(buf, size, "%s", str_error_r(err, sbuf, sizeof(sbuf))); 164 break; 165 } 166 167 return 0; 168 } 169