1 // SPDX-License-Identifier: GPL-2.0
10 #include <sys/types.h>
14 #include <sys/mount.h>
17 #include "debug-internal.h"
20 #define STR(x) _STR(x)
23 #define SYSFS_MAGIC 0x62656572
26 #ifndef PROC_SUPER_MAGIC
27 #define PROC_SUPER_MAGIC 0x9fa0
31 #define DEBUGFS_MAGIC 0x64626720
35 #define TRACEFS_MAGIC 0x74726163
38 #ifndef HUGETLBFS_MAGIC
39 #define HUGETLBFS_MAGIC 0x958458f6
43 #define BPF_FS_MAGIC 0xcafe4a11
46 static const char * const sysfs__fs_known_mountpoints[] = {
51 static const char * const procfs__known_mountpoints[] = {
56 #ifndef DEBUGFS_DEFAULT_PATH
57 #define DEBUGFS_DEFAULT_PATH "/sys/kernel/debug"
60 static const char * const debugfs__known_mountpoints[] = {
67 #ifndef TRACEFS_DEFAULT_PATH
68 #define TRACEFS_DEFAULT_PATH "/sys/kernel/tracing"
71 static const char * const tracefs__known_mountpoints[] = {
73 "/sys/kernel/debug/tracing",
79 static const char * const hugetlbfs__known_mountpoints[] = {
83 static const char * const bpf_fs__known_mountpoints[] = {
90 const char * const *mounts;
105 #ifndef TRACEFS_MAGIC
106 #define TRACEFS_MAGIC 0x74726163
109 static struct fs fs__entries[] = {
112 .mounts = sysfs__fs_known_mountpoints,
113 .magic = SYSFS_MAGIC,
117 .mounts = procfs__known_mountpoints,
118 .magic = PROC_SUPER_MAGIC,
122 .mounts = debugfs__known_mountpoints,
123 .magic = DEBUGFS_MAGIC,
127 .mounts = tracefs__known_mountpoints,
128 .magic = TRACEFS_MAGIC,
132 .mounts = hugetlbfs__known_mountpoints,
133 .magic = HUGETLBFS_MAGIC,
137 .mounts = bpf_fs__known_mountpoints,
138 .magic = BPF_FS_MAGIC,
142 static bool fs__read_mounts(struct fs *fs)
148 fp = fopen("/proc/mounts", "r");
153 fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
154 fs->path, type) == 2) {
156 if (strcmp(type, fs->name) == 0)
161 return fs->found = found;
164 static int fs__valid_mount(const char *fs, long magic)
168 if (statfs(fs, &st_fs) < 0)
170 else if ((long)st_fs.f_type != magic)
176 static bool fs__check_mounts(struct fs *fs)
178 const char * const *ptr;
182 if (fs__valid_mount(*ptr, fs->magic) == 0) {
184 strcpy(fs->path, *ptr);
193 static void mem_toupper(char *f, size_t len)
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
207 static bool fs__env_override(struct fs *fs)
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");
217 override_path = getenv(upper_name);
222 strncpy(fs->path, override_path, sizeof(fs->path));
226 static const char *fs__get_mountpoint(struct fs *fs)
228 if (fs__env_override(fs))
231 if (fs__check_mounts(fs))
234 if (fs__read_mounts(fs))
240 static const char *fs__mountpoint(int idx)
242 struct fs *fs = &fs__entries[idx];
245 return (const char *)fs->path;
247 return fs__get_mountpoint(fs);
250 static const char *mount_overload(struct fs *fs)
252 size_t name_len = strlen(fs->name);
253 /* "PERF_" + name + "_ENVIRONMENT" + '\0' */
254 char upper_name[5 + name_len + 12 + 1];
256 snprintf(upper_name, name_len, "PERF_%s_ENVIRONMENT", fs->name);
257 mem_toupper(upper_name, name_len);
259 return getenv(upper_name) ?: *fs->mounts;
262 static const char *fs__mount(int idx)
264 struct fs *fs = &fs__entries[idx];
265 const char *mountpoint;
267 if (fs__mountpoint(idx))
268 return (const char *)fs->path;
270 mountpoint = mount_overload(fs);
272 if (mount(NULL, mountpoint, fs->name, 0, NULL) < 0)
275 return fs__check_mounts(fs) ? fs->path : NULL;
278 #define FS(name, idx) \
279 const char *name##__mountpoint(void) \
281 return fs__mountpoint(idx); \
284 const char *name##__mount(void) \
286 return fs__mount(idx); \
289 bool name##__configured(void) \
291 return name##__mountpoint() != NULL; \
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);
301 int filename__read_int(const char *filename, int *value)
304 int fd = open(filename, O_RDONLY), err = -1;
309 if (read(fd, line, sizeof(line)) > 0) {
318 static int filename__read_ull_base(const char *filename,
319 unsigned long long *value, int base)
322 int fd = open(filename, O_RDONLY), err = -1;
327 if (read(fd, line, sizeof(line)) > 0) {
328 *value = strtoull(line, NULL, base);
329 if (*value != ULLONG_MAX)
338 * Parses @value out of @filename with strtoull.
339 * By using 16 for base to treat the number as hex.
341 int filename__read_xll(const char *filename, unsigned long long *value)
343 return filename__read_ull_base(filename, value, 16);
347 * Parses @value out of @filename with strtoull.
348 * By using 0 for base, the strtoull detects the
349 * base automatically (see man strtoull).
351 int filename__read_ull(const char *filename, unsigned long long *value)
353 return filename__read_ull_base(filename, value, 0);
356 #define STRERR_BUFSIZE 128 /* For the buffer size of strerror_r */
358 int filename__read_str(const char *filename, char **buf, size_t *sizep)
360 size_t size = 0, alloc_size = 0;
361 void *bf = NULL, *nbf;
363 char sbuf[STRERR_BUFSIZE];
365 fd = open(filename, O_RDONLY);
370 if (size == alloc_size) {
371 alloc_size += BUFSIZ;
372 nbf = realloc(bf, alloc_size);
381 n = read(fd, bf + size, alloc_size - size);
384 pr_warning("read failed %d: %s\n", errno,
385 strerror_r(errno, sbuf, sizeof(sbuf)));
406 int filename__write_int(const char *filename, int value)
408 int fd = open(filename, O_WRONLY), err = -1;
414 sprintf(buf, "%d", value);
415 if (write(fd, buf, sizeof(buf)) == sizeof(buf))
422 int procfs__read_str(const char *entry, char **buf, size_t *sizep)
425 const char *procfs = procfs__mountpoint();
430 snprintf(path, sizeof(path), "%s/%s", procfs, entry);
432 return filename__read_str(path, buf, sizep);
435 static int sysfs__read_ull_base(const char *entry,
436 unsigned long long *value, int base)
439 const char *sysfs = sysfs__mountpoint();
444 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
446 return filename__read_ull_base(path, value, base);
449 int sysfs__read_xll(const char *entry, unsigned long long *value)
451 return sysfs__read_ull_base(entry, value, 16);
454 int sysfs__read_ull(const char *entry, unsigned long long *value)
456 return sysfs__read_ull_base(entry, value, 0);
459 int sysfs__read_int(const char *entry, int *value)
462 const char *sysfs = sysfs__mountpoint();
467 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
469 return filename__read_int(path, value);
472 int sysfs__read_str(const char *entry, char **buf, size_t *sizep)
475 const char *sysfs = sysfs__mountpoint();
480 snprintf(path, sizeof(path), "%s/%s", sysfs, entry);
482 return filename__read_str(path, buf, sizep);
485 int sysfs__read_bool(const char *entry, bool *value)
491 ret = sysfs__read_str(entry, &buf, &size);
514 int sysctl__read_int(const char *sysctl, int *value)
517 const char *procfs = procfs__mountpoint();
522 snprintf(path, sizeof(path), "%s/sys/%s", procfs, sysctl);
524 return filename__read_int(path, value);
527 int sysfs__write_int(const char *entry, int value)
530 const char *sysfs = sysfs__mountpoint();
535 if (snprintf(path, sizeof(path), "%s/%s", sysfs, entry) >= PATH_MAX)
538 return filename__write_int(path, value);