1
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
204
205
206
207static bool fs__env_override(struct fs *fs)
208{
209 char *override_path;
210 size_t name_len = strlen(fs->name);
211
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
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
318
319
320
321
322
323int filename__read_ull(const char *filename, unsigned long long *value)
324{
325 char line[64];
326 int fd = open(filename, O_RDONLY), err = -1;
327
328 if (fd < 0)
329 return -1;
330
331 if (read(fd, line, sizeof(line)) > 0) {
332 *value = strtoull(line, NULL, 0);
333 if (*value != ULLONG_MAX)
334 err = 0;
335 }
336
337 close(fd);
338 return err;
339}
340
341#define STRERR_BUFSIZE 128
342
343int filename__read_str(const char *filename, char **buf, size_t *sizep)
344{
345 size_t size = 0, alloc_size = 0;
346 void *bf = NULL, *nbf;
347 int fd, n, err = 0;
348 char sbuf[STRERR_BUFSIZE];
349
350 fd = open(filename, O_RDONLY);
351 if (fd < 0)
352 return -errno;
353
354 do {
355 if (size == alloc_size) {
356 alloc_size += BUFSIZ;
357 nbf = realloc(bf, alloc_size);
358 if (!nbf) {
359 err = -ENOMEM;
360 break;
361 }
362
363 bf = nbf;
364 }
365
366 n = read(fd, bf + size, alloc_size - size);
367 if (n < 0) {
368 if (size) {
369 pr_warning("read failed %d: %s\n", errno,
370 strerror_r(errno, sbuf, sizeof(sbuf)));
371 err = 0;
372 } else
373 err = -errno;
374
375 break;
376 }
377
378 size += n;
379 } while (n > 0);
380
381 if (!err) {
382 *sizep = size;
383 *buf = bf;
384 } else
385 free(bf);
386
387 close(fd);
388 return err;
389}
390
391int filename__write_int(const char *filename, int value)
392{
393 int fd = open(filename, O_WRONLY), err = -1;
394 char buf[64];
395
396 if (fd < 0)
397 return err;
398
399 sprintf(buf, "%d", value);
400 if (write(fd, buf, sizeof(buf)) == sizeof(buf))
401 err = 0;
402
403 close(fd);
404 return err;
405}
406
407int procfs__read_str(const char *entry, char **buf, size_t *sizep)
408{
409 char path[PATH_MAX];
410 const char *procfs = procfs__mountpoint();
411
412 if (!procfs)
413 return -1;
414
415 snprintf(path, sizeof(path), "%s/%s", procfs, entry);
416
417 return filename__read_str(path, buf, sizep);
418}
419
420int sysfs__read_ull(const char *entry, unsigned long long *value)
421{
422 char path[PATH_MAX];
423 const char *sysfs = sysfs__mountpoint();
424
425 if (!sysfs)
426 return -1;
427
428 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
429
430 return filename__read_ull(path, value);
431}
432
433int sysfs__read_int(const char *entry, int *value)
434{
435 char path[PATH_MAX];
436 const char *sysfs = sysfs__mountpoint();
437
438 if (!sysfs)
439 return -1;
440
441 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
442
443 return filename__read_int(path, value);
444}
445
446int sysfs__read_str(const char *entry, char **buf, size_t *sizep)
447{
448 char path[PATH_MAX];
449 const char *sysfs = sysfs__mountpoint();
450
451 if (!sysfs)
452 return -1;
453
454 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
455
456 return filename__read_str(path, buf, sizep);
457}
458
459int sysfs__read_bool(const char *entry, bool *value)
460{
461 char *buf;
462 size_t size;
463 int ret;
464
465 ret = sysfs__read_str(entry, &buf, &size);
466 if (ret < 0)
467 return ret;
468
469 switch (buf[0]) {
470 case '1':
471 case 'y':
472 case 'Y':
473 *value = true;
474 break;
475 case '0':
476 case 'n':
477 case 'N':
478 *value = false;
479 break;
480 default:
481 ret = -1;
482 }
483
484 free(buf);
485
486 return ret;
487}
488int sysctl__read_int(const char *sysctl, int *value)
489{
490 char path[PATH_MAX];
491 const char *procfs = procfs__mountpoint();
492
493 if (!procfs)
494 return -1;
495
496 snprintf(path, sizeof(path), "%s/sys/%s", procfs, sysctl);
497
498 return filename__read_int(path, value);
499}
500
501int sysfs__write_int(const char *entry, int value)
502{
503 char path[PATH_MAX];
504 const char *sysfs = sysfs__mountpoint();
505
506 if (!sysfs)
507 return -1;
508
509 if (snprintf(path, sizeof(path), "%s/%s", sysfs, entry) >= PATH_MAX)
510 return -1;
511
512 return filename__write_int(path, value);
513}
514
