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 17 char tracing_mnt[PATH_MAX] = "/sys/kernel/debug"; 18 char tracing_path[PATH_MAX] = "/sys/kernel/debug/tracing"; 19 char tracing_events_path[PATH_MAX] = "/sys/kernel/debug/tracing/events"; 20 21 22 static void __tracing_path_set(const char *tracing, const char *mountpoint) 23 { 24 snprintf(tracing_mnt, sizeof(tracing_mnt), "%s", mountpoint); 25 snprintf(tracing_path, sizeof(tracing_path), "%s/%s", 26 mountpoint, tracing); 27 snprintf(tracing_events_path, sizeof(tracing_events_path), "%s/%s%s", 28 mountpoint, tracing, "events"); 29 } 30 31 static const char *tracing_path_tracefs_mount(void) 32 { 33 const char *mnt; 34 35 mnt = tracefs__mount(); 36 if (!mnt) 37 return NULL; 38 39 __tracing_path_set("", mnt); 40 41 return mnt; 42 } 43 44 static const char *tracing_path_debugfs_mount(void) 45 { 46 const char *mnt; 47 48 mnt = debugfs__mount(); 49 if (!mnt) 50 return NULL; 51 52 __tracing_path_set("tracing/", mnt); 53 54 return mnt; 55 } 56 57 const char *tracing_path_mount(void) 58 { 59 const char *mnt; 60 61 mnt = tracing_path_tracefs_mount(); 62 if (mnt) 63 return mnt; 64 65 mnt = tracing_path_debugfs_mount(); 66 67 return mnt; 68 } 69 70 void tracing_path_set(const char *mntpt) 71 { 72 __tracing_path_set("tracing/", mntpt); 73 } 74 75 char *get_tracing_file(const char *name) 76 { 77 char *file; 78 79 if (asprintf(&file, "%s/%s", tracing_path, name) < 0) 80 return NULL; 81 82 return file; 83 } 84 85 void put_tracing_file(char *file) 86 { 87 free(file); 88 } 89 90 int tracing_path__strerror_open_tp(int err, char *buf, size_t size, 91 const char *sys, const char *name) 92 { 93 char sbuf[128]; 94 char filename[PATH_MAX]; 95 96 snprintf(filename, PATH_MAX, "%s/%s", sys, name ?: "*"); 97 98 switch (err) { 99 case ENOENT: 100 /* 101 * We will get here if we can't find the tracepoint, but one of 102 * debugfs or tracefs is configured, which means you probably 103 * want some tracepoint which wasn't compiled in your kernel. 104 * - jirka 105 */ 106 if (debugfs__configured() || tracefs__configured()) { 107 /* sdt markers */ 108 if (!strncmp(filename, "sdt_", 4)) { 109 snprintf(buf, size, 110 "Error:\tFile %s/%s not found.\n" 111 "Hint:\tSDT event cannot be directly recorded on.\n" 112 "\tPlease first use 'perf probe %s:%s' before recording it.\n", 113 tracing_events_path, filename, sys, name); 114 } else { 115 snprintf(buf, size, 116 "Error:\tFile %s/%s not found.\n" 117 "Hint:\tPerhaps this kernel misses some CONFIG_ setting to enable this feature?.\n", 118 tracing_events_path, filename); 119 } 120 break; 121 } 122 snprintf(buf, size, "%s", 123 "Error:\tUnable to find debugfs/tracefs\n" 124 "Hint:\tWas your kernel compiled with debugfs/tracefs support?\n" 125 "Hint:\tIs the debugfs/tracefs filesystem mounted?\n" 126 "Hint:\tTry 'sudo mount -t debugfs nodev /sys/kernel/debug'"); 127 break; 128 case EACCES: { 129 snprintf(buf, size, 130 "Error:\tNo permissions to read %s/%s\n" 131 "Hint:\tTry 'sudo mount -o remount,mode=755 %s'\n", 132 tracing_events_path, filename, tracing_mnt); 133 } 134 break; 135 default: 136 snprintf(buf, size, "%s", str_error_r(err, sbuf, sizeof(sbuf))); 137 break; 138 } 139 140 return 0; 141 } 142