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1/* TODO merge/factor in debugfs.c here */
2
3#include <errno.h>
4#include <stdbool.h>
5#include <stdio.h>
6#include <string.h>
7#include <sys/vfs.h>
8
9#include "debugfs.h"
10#include "fs.h"
11
12static const char * const sysfs__fs_known_mountpoints[] = {
13 "/sys",
14 0,
15};
16
17static const char * const procfs__known_mountpoints[] = {
18 "/proc",
19 0,
20};
21
22struct fs {
23 const char *name;
24 const char * const *mounts;
25 char path[PATH_MAX + 1];
26 bool found;
27 long magic;
28};
29
30enum {
31 FS__SYSFS = 0,
32 FS__PROCFS = 1,
33};
34
35static struct fs fs__entries[] = {
36 [FS__SYSFS] = {
37 .name = "sysfs",
38 .mounts = sysfs__fs_known_mountpoints,
39 .magic = SYSFS_MAGIC,
40 },
41 [FS__PROCFS] = {
42 .name = "proc",
43 .mounts = procfs__known_mountpoints,
44 .magic = PROC_SUPER_MAGIC,
45 },
46};
47
48static bool fs__read_mounts(struct fs *fs)
49{
50 bool found = false;
51 char type[100];
52 FILE *fp;
53
54 fp = fopen("/proc/mounts", "r");
55 if (fp == NULL)
56 return NULL;
57
58 while (!found &&
59 fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
60 fs->path, type) == 2) {
61
62 if (strcmp(type, fs->name) == 0)
63 found = true;
64 }
65
66 fclose(fp);
67 return fs->found = found;
68}
69
70static int fs__valid_mount(const char *fs, long magic)
71{
72 struct statfs st_fs;
73
74 if (statfs(fs, &st_fs) < 0)
75 return -ENOENT;
76 else if (st_fs.f_type != magic)
77 return -ENOENT;
78
79 return 0;
80}
81
82static bool fs__check_mounts(struct fs *fs)
83{
84 const char * const *ptr;
85
86 ptr = fs->mounts;
87 while (*ptr) {
88 if (fs__valid_mount(*ptr, fs->magic) == 0) {
89 fs->found = true;
90 strcpy(fs->path, *ptr);
91 return true;
92 }
93 ptr++;
94 }
95
96 return false;
97}
98
99static const char *fs__get_mountpoint(struct fs *fs)
100{
101 if (fs__check_mounts(fs))
102 return fs->path;
103
104 return fs__read_mounts(fs) ? fs->path : NULL;
105}
106
107static const char *fs__mountpoint(int idx)
108{
109 struct fs *fs = &fs__entries[idx];
110
111 if (fs->found)
112 return (const char *)fs->path;
113
114 return fs__get_mountpoint(fs);
115}
116
117#define FS__MOUNTPOINT(name, idx) \
118const char *name##__mountpoint(void) \
119{ \
120 return fs__mountpoint(idx); \
121}
122
123FS__MOUNTPOINT(sysfs, FS__SYSFS);
124FS__MOUNTPOINT(procfs, FS__PROCFS);
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
46static const char * const sysfs__fs_known_mountpoints[] = {
47 "/sys",
48 0,
49};
50
51static 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
60static 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
71static const char * const tracefs__known_mountpoints[] = {
72 TRACEFS_DEFAULT_PATH,
73 "/sys/kernel/debug/tracing",
74 "/tracing",
75 "/trace",
76 0,
77};
78
79static const char * const hugetlbfs__known_mountpoints[] = {
80 0,
81};
82
83static const char * const bpf_fs__known_mountpoints[] = {
84 "/sys/fs/bpf",
85 0,
86};
87
88struct fs {
89 const char *name;
90 const char * const *mounts;
91 char path[PATH_MAX];
92 bool found;
93 long magic;
94};
95
96enum {
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
109static 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
142static 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
164static 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
176static 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
193static 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 */
207static 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
226static 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
240static 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
250static 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
262static 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) \
279const char *name##__mountpoint(void) \
280{ \
281 return fs__mountpoint(idx); \
282} \
283 \
284const char *name##__mount(void) \
285{ \
286 return fs__mount(idx); \
287} \
288 \
289bool name##__configured(void) \
290{ \
291 return name##__mountpoint() != NULL; \
292}
293
294FS(sysfs, FS__SYSFS);
295FS(procfs, FS__PROCFS);
296FS(debugfs, FS__DEBUGFS);
297FS(tracefs, FS__TRACEFS);
298FS(hugetlbfs, FS__HUGETLBFS);
299FS(bpf_fs, FS__BPF_FS);
300
301int 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
318static 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 */
341int 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 */
351int 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
358int 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
406int 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
422int 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
435static 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
449int sysfs__read_xll(const char *entry, unsigned long long *value)
450{
451 return sysfs__read_ull_base(entry, value, 16);
452}
453
454int sysfs__read_ull(const char *entry, unsigned long long *value)
455{
456 return sysfs__read_ull_base(entry, value, 0);
457}
458
459int 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
472int 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
485int 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}
514int 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
527int 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}