1 #include <ctype.h> 2 #include <errno.h> 3 #include <limits.h> 4 #include <stdbool.h> 5 #include <stdio.h> 6 #include <stdlib.h> 7 #include <string.h> 8 #include <sys/vfs.h> 9 #include <sys/types.h> 10 #include <sys/stat.h> 11 #include <fcntl.h> 12 #include <unistd.h> 13 #include <sys/mount.h> 14 15 #include "fs.h" 16 #include "debug-internal.h" 17 18 #define _STR(x) #x 19 #define STR(x) _STR(x) 20 21 #ifndef SYSFS_MAGIC 22 #define SYSFS_MAGIC 0x62656572 23 #endif 24 25 #ifndef PROC_SUPER_MAGIC 26 #define PROC_SUPER_MAGIC 0x9fa0 27 #endif 28 29 #ifndef DEBUGFS_MAGIC 30 #define DEBUGFS_MAGIC 0x64626720 31 #endif 32 33 #ifndef TRACEFS_MAGIC 34 #define TRACEFS_MAGIC 0x74726163 35 #endif 36 37 #ifndef HUGETLBFS_MAGIC 38 #define HUGETLBFS_MAGIC 0x958458f6 39 #endif 40 41 #ifndef BPF_FS_MAGIC 42 #define BPF_FS_MAGIC 0xcafe4a11 43 #endif 44 45 static const char * const sysfs__fs_known_mountpoints[] = { 46 "/sys", 47 0, 48 }; 49 50 static const char * const procfs__known_mountpoints[] = { 51 "/proc", 52 0, 53 }; 54 55 #ifndef DEBUGFS_DEFAULT_PATH 56 #define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug" 57 #endif 58 59 static const char * const debugfs__known_mountpoints[] = { 60 DEBUGFS_DEFAULT_PATH, 61 "/debug", 62 0, 63 }; 64 65 66 #ifndef TRACEFS_DEFAULT_PATH 67 #define TRACEFS_DEFAULT_PATH "/sys/kernel/tracing" 68 #endif 69 70 static const char * const tracefs__known_mountpoints[] = { 71 TRACEFS_DEFAULT_PATH, 72 "/sys/kernel/debug/tracing", 73 "/tracing", 74 "/trace", 75 0, 76 }; 77 78 static const char * const hugetlbfs__known_mountpoints[] = { 79 0, 80 }; 81 82 static const char * const bpf_fs__known_mountpoints[] = { 83 "/sys/fs/bpf", 84 0, 85 }; 86 87 struct fs { 88 const char *name; 89 const char * const *mounts; 90 char path[PATH_MAX]; 91 bool found; 92 long magic; 93 }; 94 95 enum { 96 FS__SYSFS = 0, 97 FS__PROCFS = 1, 98 FS__DEBUGFS = 2, 99 FS__TRACEFS = 3, 100 FS__HUGETLBFS = 4, 101 FS__BPF_FS = 5, 102 }; 103 104 #ifndef TRACEFS_MAGIC 105 #define TRACEFS_MAGIC 0x74726163 106 #endif 107 108 static struct fs fs__entries[] = { 109 [FS__SYSFS] = { 110 .name = "sysfs", 111 .mounts = sysfs__fs_known_mountpoints, 112 .magic = SYSFS_MAGIC, 113 }, 114 [FS__PROCFS] = { 115 .name = "proc", 116 .mounts = procfs__known_mountpoints, 117 .magic = PROC_SUPER_MAGIC, 118 }, 119 [FS__DEBUGFS] = { 120 .name = "debugfs", 121 .mounts = debugfs__known_mountpoints, 122 .magic = DEBUGFS_MAGIC, 123 }, 124 [FS__TRACEFS] = { 125 .name = "tracefs", 126 .mounts = tracefs__known_mountpoints, 127 .magic = TRACEFS_MAGIC, 128 }, 129 [FS__HUGETLBFS] = { 130 .name = "hugetlbfs", 131 .mounts = hugetlbfs__known_mountpoints, 132 .magic = HUGETLBFS_MAGIC, 133 }, 134 [FS__BPF_FS] = { 135 .name = "bpf", 136 .mounts = bpf_fs__known_mountpoints, 137 .magic = BPF_FS_MAGIC, 138 }, 139 }; 140 141 static bool fs__read_mounts(struct fs *fs) 142 { 143 bool found = false; 144 char type[100]; 145 FILE *fp; 146 147 fp = fopen("/proc/mounts", "r"); 148 if (fp == NULL) 149 return NULL; 150 151 while (!found && 152 fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n", 153 fs->path, type) == 2) { 154 155 if (strcmp(type, fs->name) == 0) 156 found = true; 157 } 158 159 fclose(fp); 160 return fs->found = found; 161 } 162 163 static int fs__valid_mount(const char *fs, long magic) 164 { 165 struct statfs st_fs; 166 167 if (statfs(fs, &st_fs) < 0) 168 return -ENOENT; 169 else if ((long)st_fs.f_type != magic) 170 return -ENOENT; 171 172 return 0; 173 } 174 175 static bool fs__check_mounts(struct fs *fs) 176 { 177 const char * const *ptr; 178 179 ptr = fs->mounts; 180 while (*ptr) { 181 if (fs__valid_mount(*ptr, fs->magic) == 0) { 182 fs->found = true; 183 strcpy(fs->path, *ptr); 184 return true; 185 } 186 ptr++; 187 } 188 189 return false; 190 } 191 192 static void mem_toupper(char *f, size_t len) 193 { 194 while (len) { 195 *f = toupper(*f); 196 f++; 197 len--; 198 } 199 } 200 201 /* 202 * Check for "NAME_PATH" environment variable to override fs location (for 203 * testing). This matches the recommendation in Documentation/sysfs-rules.txt 204 * for SYSFS_PATH. 205 */ 206 static bool fs__env_override(struct fs *fs) 207 { 208 char *override_path; 209 size_t name_len = strlen(fs->name); 210 /* name + "_PATH" + '\0' */ 211 char upper_name[name_len + 5 + 1]; 212 memcpy(upper_name, fs->name, name_len); 213 mem_toupper(upper_name, name_len); 214 strcpy(&upper_name[name_len], "_PATH"); 215 216 override_path = getenv(upper_name); 217 if (!override_path) 218 return false; 219 220 fs->found = true; 221 strncpy(fs->path, override_path, sizeof(fs->path)); 222 return true; 223 } 224 225 static const char *fs__get_mountpoint(struct fs *fs) 226 { 227 if (fs__env_override(fs)) 228 return fs->path; 229 230 if (fs__check_mounts(fs)) 231 return fs->path; 232 233 if (fs__read_mounts(fs)) 234 return fs->path; 235 236 return NULL; 237 } 238 239 static const char *fs__mountpoint(int idx) 240 { 241 struct fs *fs = &fs__entries[idx]; 242 243 if (fs->found) 244 return (const char *)fs->path; 245 246 return fs__get_mountpoint(fs); 247 } 248 249 static const char *mount_overload(struct fs *fs) 250 { 251 size_t name_len = strlen(fs->name); 252 /* "PERF_" + name + "_ENVIRONMENT" + '\0' */ 253 char upper_name[5 + name_len + 12 + 1]; 254 255 snprintf(upper_name, name_len, "PERF_%s_ENVIRONMENT", fs->name); 256 mem_toupper(upper_name, name_len); 257 258 return getenv(upper_name) ?: *fs->mounts; 259 } 260 261 static const char *fs__mount(int idx) 262 { 263 struct fs *fs = &fs__entries[idx]; 264 const char *mountpoint; 265 266 if (fs__mountpoint(idx)) 267 return (const char *)fs->path; 268 269 mountpoint = mount_overload(fs); 270 271 if (mount(NULL, mountpoint, fs->name, 0, NULL) < 0) 272 return NULL; 273 274 return fs__check_mounts(fs) ? fs->path : NULL; 275 } 276 277 #define FS(name, idx) \ 278 const char *name##__mountpoint(void) \ 279 { \ 280 return fs__mountpoint(idx); \ 281 } \ 282 \ 283 const char *name##__mount(void) \ 284 { \ 285 return fs__mount(idx); \ 286 } \ 287 \ 288 bool name##__configured(void) \ 289 { \ 290 return name##__mountpoint() != NULL; \ 291 } 292 293 FS(sysfs, FS__SYSFS); 294 FS(procfs, FS__PROCFS); 295 FS(debugfs, FS__DEBUGFS); 296 FS(tracefs, FS__TRACEFS); 297 FS(hugetlbfs, FS__HUGETLBFS); 298 FS(bpf_fs, FS__BPF_FS); 299 300 int filename__read_int(const char *filename, int *value) 301 { 302 char line[64]; 303 int fd = open(filename, O_RDONLY), err = -1; 304 305 if (fd < 0) 306 return -1; 307 308 if (read(fd, line, sizeof(line)) > 0) { 309 *value = atoi(line); 310 err = 0; 311 } 312 313 close(fd); 314 return err; 315 } 316 317 /* 318 * Parses @value out of @filename with strtoull. 319 * By using 0 for base, the strtoull detects the 320 * base automatically (see man strtoull). 321 */ 322 int filename__read_ull(const char *filename, unsigned long long *value) 323 { 324 char line[64]; 325 int fd = open(filename, O_RDONLY), err = -1; 326 327 if (fd < 0) 328 return -1; 329 330 if (read(fd, line, sizeof(line)) > 0) { 331 *value = strtoull(line, NULL, 0); 332 if (*value != ULLONG_MAX) 333 err = 0; 334 } 335 336 close(fd); 337 return err; 338 } 339 340 #define STRERR_BUFSIZE 128 /* For the buffer size of strerror_r */ 341 342 int filename__read_str(const char *filename, char **buf, size_t *sizep) 343 { 344 size_t size = 0, alloc_size = 0; 345 void *bf = NULL, *nbf; 346 int fd, n, err = 0; 347 char sbuf[STRERR_BUFSIZE]; 348 349 fd = open(filename, O_RDONLY); 350 if (fd < 0) 351 return -errno; 352 353 do { 354 if (size == alloc_size) { 355 alloc_size += BUFSIZ; 356 nbf = realloc(bf, alloc_size); 357 if (!nbf) { 358 err = -ENOMEM; 359 break; 360 } 361 362 bf = nbf; 363 } 364 365 n = read(fd, bf + size, alloc_size - size); 366 if (n < 0) { 367 if (size) { 368 pr_warning("read failed %d: %s\n", errno, 369 strerror_r(errno, sbuf, sizeof(sbuf))); 370 err = 0; 371 } else 372 err = -errno; 373 374 break; 375 } 376 377 size += n; 378 } while (n > 0); 379 380 if (!err) { 381 *sizep = size; 382 *buf = bf; 383 } else 384 free(bf); 385 386 close(fd); 387 return err; 388 } 389 390 int procfs__read_str(const char *entry, char **buf, size_t *sizep) 391 { 392 char path[PATH_MAX]; 393 const char *procfs = procfs__mountpoint(); 394 395 if (!procfs) 396 return -1; 397 398 snprintf(path, sizeof(path), "%s/%s", procfs, entry); 399 400 return filename__read_str(path, buf, sizep); 401 } 402 403 int sysfs__read_ull(const char *entry, unsigned long long *value) 404 { 405 char path[PATH_MAX]; 406 const char *sysfs = sysfs__mountpoint(); 407 408 if (!sysfs) 409 return -1; 410 411 snprintf(path, sizeof(path), "%s/%s", sysfs, entry); 412 413 return filename__read_ull(path, value); 414 } 415 416 int sysfs__read_int(const char *entry, int *value) 417 { 418 char path[PATH_MAX]; 419 const char *sysfs = sysfs__mountpoint(); 420 421 if (!sysfs) 422 return -1; 423 424 snprintf(path, sizeof(path), "%s/%s", sysfs, entry); 425 426 return filename__read_int(path, value); 427 } 428 429 int sysfs__read_str(const char *entry, char **buf, size_t *sizep) 430 { 431 char path[PATH_MAX]; 432 const char *sysfs = sysfs__mountpoint(); 433 434 if (!sysfs) 435 return -1; 436 437 snprintf(path, sizeof(path), "%s/%s", sysfs, entry); 438 439 return filename__read_str(path, buf, sizep); 440 } 441 442 int sysctl__read_int(const char *sysctl, int *value) 443 { 444 char path[PATH_MAX]; 445 const char *procfs = procfs__mountpoint(); 446 447 if (!procfs) 448 return -1; 449 450 snprintf(path, sizeof(path), "%s/sys/%s", procfs, sysctl); 451 452 return filename__read_int(path, value); 453 } 454