1 // SPDX-License-Identifier: GPL-2.0
2 #include <ctype.h>
3 #include <errno.h>
4 #include <limits.h>
5 #include <stdbool.h>
6 #include <stdio.h>
7 #include <stdlib.h>
8 #include <string.h>
9 #include <sys/vfs.h>
10 #include <sys/types.h>
11 #include <sys/stat.h>
12 #include <fcntl.h>
13 #include <unistd.h>
14 #include <sys/mount.h>
15
16 #include "fs.h"
17 #include "debug-internal.h"
18
19 #define _STR(x) #x
20 #define STR(x) _STR(x)
21
22 #ifndef SYSFS_MAGIC
23 #define SYSFS_MAGIC 0x62656572
24 #endif
25
26 #ifndef PROC_SUPER_MAGIC
27 #define PROC_SUPER_MAGIC 0x9fa0
28 #endif
29
30 #ifndef DEBUGFS_MAGIC
31 #define DEBUGFS_MAGIC 0x64626720
32 #endif
33
34 #ifndef TRACEFS_MAGIC
35 #define TRACEFS_MAGIC 0x74726163
36 #endif
37
38 #ifndef HUGETLBFS_MAGIC
39 #define HUGETLBFS_MAGIC 0x958458f6
40 #endif
41
42 #ifndef BPF_FS_MAGIC
43 #define BPF_FS_MAGIC 0xcafe4a11
44 #endif
45
46 static const char * const sysfs__fs_known_mountpoints[] = {
47 "/sys",
48 0,
49 };
50
51 static const char * const procfs__known_mountpoints[] = {
52 "/proc",
53 0,
54 };
55
56 #ifndef DEBUGFS_DEFAULT_PATH
57 #define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug"
58 #endif
59
60 static const char * const debugfs__known_mountpoints[] = {
61 DEBUGFS_DEFAULT_PATH,
62 "/debug",
63 0,
64 };
65
66
67 #ifndef TRACEFS_DEFAULT_PATH
68 #define TRACEFS_DEFAULT_PATH "/sys/kernel/tracing"
69 #endif
70
71 static const char * const tracefs__known_mountpoints[] = {
72 TRACEFS_DEFAULT_PATH,
73 "/sys/kernel/debug/tracing",
74 "/tracing",
75 "/trace",
76 0,
77 };
78
79 static const char * const hugetlbfs__known_mountpoints[] = {
80 0,
81 };
82
83 static const char * const bpf_fs__known_mountpoints[] = {
84 "/sys/fs/bpf",
85 0,
86 };
87
88 struct fs {
89 const char *name;
90 const char * const *mounts;
91 char path[PATH_MAX];
92 bool found;
93 long magic;
94 };
95
96 enum {
97 FS__SYSFS = 0,
98 FS__PROCFS = 1,
99 FS__DEBUGFS = 2,
100 FS__TRACEFS = 3,
101 FS__HUGETLBFS = 4,
102 FS__BPF_FS = 5,
103 };
104
105 #ifndef TRACEFS_MAGIC
106 #define TRACEFS_MAGIC 0x74726163
107 #endif
108
109 static struct fs fs__entries[] = {
110 [FS__SYSFS] = {
111 .name = "sysfs",
112 .mounts = sysfs__fs_known_mountpoints,
113 .magic = SYSFS_MAGIC,
114 },
115 [FS__PROCFS] = {
116 .name = "proc",
117 .mounts = procfs__known_mountpoints,
118 .magic = PROC_SUPER_MAGIC,
119 },
120 [FS__DEBUGFS] = {
121 .name = "debugfs",
122 .mounts = debugfs__known_mountpoints,
123 .magic = DEBUGFS_MAGIC,
124 },
125 [FS__TRACEFS] = {
126 .name = "tracefs",
127 .mounts = tracefs__known_mountpoints,
128 .magic = TRACEFS_MAGIC,
129 },
130 [FS__HUGETLBFS] = {
131 .name = "hugetlbfs",
132 .mounts = hugetlbfs__known_mountpoints,
133 .magic = HUGETLBFS_MAGIC,
134 },
135 [FS__BPF_FS] = {
136 .name = "bpf",
137 .mounts = bpf_fs__known_mountpoints,
138 .magic = BPF_FS_MAGIC,
139 },
140 };
141
fs__read_mounts(struct fs * fs)142 static bool fs__read_mounts(struct fs *fs)
143 {
144 bool found = false;
145 char type[100];
146 FILE *fp;
147
148 fp = fopen("/proc/mounts", "r");
149 if (fp == NULL)
150 return NULL;
151
152 while (!found &&
153 fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
154 fs->path, type) == 2) {
155
156 if (strcmp(type, fs->name) == 0)
157 found = true;
158 }
159
160 fclose(fp);
161 return fs->found = found;
162 }
163
fs__valid_mount(const char * fs,long magic)164 static int fs__valid_mount(const char *fs, long magic)
165 {
166 struct statfs st_fs;
167
168 if (statfs(fs, &st_fs) < 0)
169 return -ENOENT;
170 else if ((long)st_fs.f_type != magic)
171 return -ENOENT;
172
173 return 0;
174 }
175
fs__check_mounts(struct fs * fs)176 static bool fs__check_mounts(struct fs *fs)
177 {
178 const char * const *ptr;
179
180 ptr = fs->mounts;
181 while (*ptr) {
182 if (fs__valid_mount(*ptr, fs->magic) == 0) {
183 fs->found = true;
184 strcpy(fs->path, *ptr);
185 return true;
186 }
187 ptr++;
188 }
189
190 return false;
191 }
192
mem_toupper(char * f,size_t len)193 static void mem_toupper(char *f, size_t len)
194 {
195 while (len) {
196 *f = toupper(*f);
197 f++;
198 len--;
199 }
200 }
201
202 /*
203 * Check for "NAME_PATH" environment variable to override fs location (for
204 * testing). This matches the recommendation in Documentation/admin-guide/sysfs-rules.rst
205 * for SYSFS_PATH.
206 */
fs__env_override(struct fs * fs)207 static bool fs__env_override(struct fs *fs)
208 {
209 char *override_path;
210 size_t name_len = strlen(fs->name);
211 /* name + "_PATH" + '\0' */
212 char upper_name[name_len + 5 + 1];
213 memcpy(upper_name, fs->name, name_len);
214 mem_toupper(upper_name, name_len);
215 strcpy(&upper_name[name_len], "_PATH");
216
217 override_path = getenv(upper_name);
218 if (!override_path)
219 return false;
220
221 fs->found = true;
222 strncpy(fs->path, override_path, sizeof(fs->path));
223 return true;
224 }
225
fs__get_mountpoint(struct fs * fs)226 static const char *fs__get_mountpoint(struct fs *fs)
227 {
228 if (fs__env_override(fs))
229 return fs->path;
230
231 if (fs__check_mounts(fs))
232 return fs->path;
233
234 if (fs__read_mounts(fs))
235 return fs->path;
236
237 return NULL;
238 }
239
fs__mountpoint(int idx)240 static const char *fs__mountpoint(int idx)
241 {
242 struct fs *fs = &fs__entries[idx];
243
244 if (fs->found)
245 return (const char *)fs->path;
246
247 return fs__get_mountpoint(fs);
248 }
249
mount_overload(struct fs * fs)250 static const char *mount_overload(struct fs *fs)
251 {
252 size_t name_len = strlen(fs->name);
253 /* "PERF_" + name + "_ENVIRONMENT" + '\0' */
254 char upper_name[5 + name_len + 12 + 1];
255
256 snprintf(upper_name, name_len, "PERF_%s_ENVIRONMENT", fs->name);
257 mem_toupper(upper_name, name_len);
258
259 return getenv(upper_name) ?: *fs->mounts;
260 }
261
fs__mount(int idx)262 static const char *fs__mount(int idx)
263 {
264 struct fs *fs = &fs__entries[idx];
265 const char *mountpoint;
266
267 if (fs__mountpoint(idx))
268 return (const char *)fs->path;
269
270 mountpoint = mount_overload(fs);
271
272 if (mount(NULL, mountpoint, fs->name, 0, NULL) < 0)
273 return NULL;
274
275 return fs__check_mounts(fs) ? fs->path : NULL;
276 }
277
278 #define FS(name, idx) \
279 const char *name##__mountpoint(void) \
280 { \
281 return fs__mountpoint(idx); \
282 } \
283 \
284 const char *name##__mount(void) \
285 { \
286 return fs__mount(idx); \
287 } \
288 \
289 bool name##__configured(void) \
290 { \
291 return name##__mountpoint() != NULL; \
292 }
293
294 FS(sysfs, FS__SYSFS);
295 FS(procfs, FS__PROCFS);
296 FS(debugfs, FS__DEBUGFS);
297 FS(tracefs, FS__TRACEFS);
298 FS(hugetlbfs, FS__HUGETLBFS);
299 FS(bpf_fs, FS__BPF_FS);
300
filename__read_int(const char * filename,int * value)301 int filename__read_int(const char *filename, int *value)
302 {
303 char line[64];
304 int fd = open(filename, O_RDONLY), err = -1;
305
306 if (fd < 0)
307 return -1;
308
309 if (read(fd, line, sizeof(line)) > 0) {
310 *value = atoi(line);
311 err = 0;
312 }
313
314 close(fd);
315 return err;
316 }
317
filename__read_ull_base(const char * filename,unsigned long long * value,int base)318 static int filename__read_ull_base(const char *filename,
319 unsigned long long *value, int base)
320 {
321 char line[64];
322 int fd = open(filename, O_RDONLY), err = -1;
323
324 if (fd < 0)
325 return -1;
326
327 if (read(fd, line, sizeof(line)) > 0) {
328 *value = strtoull(line, NULL, base);
329 if (*value != ULLONG_MAX)
330 err = 0;
331 }
332
333 close(fd);
334 return err;
335 }
336
337 /*
338 * Parses @value out of @filename with strtoull.
339 * By using 16 for base to treat the number as hex.
340 */
filename__read_xll(const char * filename,unsigned long long * value)341 int filename__read_xll(const char *filename, unsigned long long *value)
342 {
343 return filename__read_ull_base(filename, value, 16);
344 }
345
346 /*
347 * Parses @value out of @filename with strtoull.
348 * By using 0 for base, the strtoull detects the
349 * base automatically (see man strtoull).
350 */
filename__read_ull(const char * filename,unsigned long long * value)351 int filename__read_ull(const char *filename, unsigned long long *value)
352 {
353 return filename__read_ull_base(filename, value, 0);
354 }
355
356 #define STRERR_BUFSIZE 128 /* For the buffer size of strerror_r */
357
filename__read_str(const char * filename,char ** buf,size_t * sizep)358 int filename__read_str(const char *filename, char **buf, size_t *sizep)
359 {
360 size_t size = 0, alloc_size = 0;
361 void *bf = NULL, *nbf;
362 int fd, n, err = 0;
363 char sbuf[STRERR_BUFSIZE];
364
365 fd = open(filename, O_RDONLY);
366 if (fd < 0)
367 return -errno;
368
369 do {
370 if (size == alloc_size) {
371 alloc_size += BUFSIZ;
372 nbf = realloc(bf, alloc_size);
373 if (!nbf) {
374 err = -ENOMEM;
375 break;
376 }
377
378 bf = nbf;
379 }
380
381 n = read(fd, bf + size, alloc_size - size);
382 if (n < 0) {
383 if (size) {
384 pr_warning("read failed %d: %s\n", errno,
385 strerror_r(errno, sbuf, sizeof(sbuf)));
386 err = 0;
387 } else
388 err = -errno;
389
390 break;
391 }
392
393 size += n;
394 } while (n > 0);
395
396 if (!err) {
397 *sizep = size;
398 *buf = bf;
399 } else
400 free(bf);
401
402 close(fd);
403 return err;
404 }
405
filename__write_int(const char * filename,int value)406 int filename__write_int(const char *filename, int value)
407 {
408 int fd = open(filename, O_WRONLY), err = -1;
409 char buf[64];
410
411 if (fd < 0)
412 return err;
413
414 sprintf(buf, "%d", value);
415 if (write(fd, buf, sizeof(buf)) == sizeof(buf))
416 err = 0;
417
418 close(fd);
419 return err;
420 }
421
procfs__read_str(const char * entry,char ** buf,size_t * sizep)422 int procfs__read_str(const char *entry, char **buf, size_t *sizep)
423 {
424 char path[PATH_MAX];
425 const char *procfs = procfs__mountpoint();
426
427 if (!procfs)
428 return -1;
429
430 snprintf(path, sizeof(path), "%s/%s", procfs, entry);
431
432 return filename__read_str(path, buf, sizep);
433 }
434
sysfs__read_ull_base(const char * entry,unsigned long long * value,int base)435 static int sysfs__read_ull_base(const char *entry,
436 unsigned long long *value, int base)
437 {
438 char path[PATH_MAX];
439 const char *sysfs = sysfs__mountpoint();
440
441 if (!sysfs)
442 return -1;
443
444 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
445
446 return filename__read_ull_base(path, value, base);
447 }
448
sysfs__read_xll(const char * entry,unsigned long long * value)449 int sysfs__read_xll(const char *entry, unsigned long long *value)
450 {
451 return sysfs__read_ull_base(entry, value, 16);
452 }
453
sysfs__read_ull(const char * entry,unsigned long long * value)454 int sysfs__read_ull(const char *entry, unsigned long long *value)
455 {
456 return sysfs__read_ull_base(entry, value, 0);
457 }
458
sysfs__read_int(const char * entry,int * value)459 int sysfs__read_int(const char *entry, int *value)
460 {
461 char path[PATH_MAX];
462 const char *sysfs = sysfs__mountpoint();
463
464 if (!sysfs)
465 return -1;
466
467 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
468
469 return filename__read_int(path, value);
470 }
471
sysfs__read_str(const char * entry,char ** buf,size_t * sizep)472 int sysfs__read_str(const char *entry, char **buf, size_t *sizep)
473 {
474 char path[PATH_MAX];
475 const char *sysfs = sysfs__mountpoint();
476
477 if (!sysfs)
478 return -1;
479
480 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
481
482 return filename__read_str(path, buf, sizep);
483 }
484
sysfs__read_bool(const char * entry,bool * value)485 int sysfs__read_bool(const char *entry, bool *value)
486 {
487 char *buf;
488 size_t size;
489 int ret;
490
491 ret = sysfs__read_str(entry, &buf, &size);
492 if (ret < 0)
493 return ret;
494
495 switch (buf[0]) {
496 case '1':
497 case 'y':
498 case 'Y':
499 *value = true;
500 break;
501 case '0':
502 case 'n':
503 case 'N':
504 *value = false;
505 break;
506 default:
507 ret = -1;
508 }
509
510 free(buf);
511
512 return ret;
513 }
sysctl__read_int(const char * sysctl,int * value)514 int sysctl__read_int(const char *sysctl, int *value)
515 {
516 char path[PATH_MAX];
517 const char *procfs = procfs__mountpoint();
518
519 if (!procfs)
520 return -1;
521
522 snprintf(path, sizeof(path), "%s/sys/%s", procfs, sysctl);
523
524 return filename__read_int(path, value);
525 }
526
sysfs__write_int(const char * entry,int value)527 int sysfs__write_int(const char *entry, int value)
528 {
529 char path[PATH_MAX];
530 const char *sysfs = sysfs__mountpoint();
531
532 if (!sysfs)
533 return -1;
534
535 if (snprintf(path, sizeof(path), "%s/%s", sysfs, entry) >= PATH_MAX)
536 return -1;
537
538 return filename__write_int(path, value);
539 }
540