xref: /linux/init/initramfs.c (revision f4cdf7ca9a1fdcca413157df19753f388a5a224e)
1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/async.h>
3 #include <linux/delay.h>
4 #include <linux/dirent.h>
5 #include <linux/export.h>
6 #include <linux/fcntl.h>
7 #include <linux/file.h>
8 #include <linux/fs.h>
9 #include <linux/fs_struct.h>
10 #include <linux/hex.h>
11 #include <linux/init.h>
12 #include <linux/init_syscalls.h>
13 #include <linux/kstrtox.h>
14 #include <linux/memblock.h>
15 #include <linux/mm.h>
16 #include <linux/namei.h>
17 #include <linux/overflow.h>
18 #include <linux/security.h>
19 #include <linux/slab.h>
20 #include <linux/string.h>
21 #include <linux/syscalls.h>
22 #include <linux/types.h>
23 #include <linux/umh.h>
24 #include <linux/utime.h>
25 
26 #include <asm/byteorder.h>
27 
28 #include "do_mounts.h"
29 #include "initramfs_internal.h"
30 
31 static __initdata bool csum_present;
32 static __initdata u32 io_csum;
33 
34 static ssize_t __init xwrite(struct file *file, const unsigned char *p,
35 		size_t count, loff_t *pos)
36 {
37 	ssize_t out = 0;
38 
39 	/* sys_write only can write MAX_RW_COUNT aka 2G-4K bytes at most */
40 	while (count) {
41 		ssize_t rv = kernel_write(file, p, count, pos);
42 
43 		if (rv < 0) {
44 			if (rv == -EINTR || rv == -EAGAIN)
45 				continue;
46 			return out ? out : rv;
47 		} else if (rv == 0)
48 			break;
49 
50 		if (csum_present) {
51 			ssize_t i;
52 
53 			for (i = 0; i < rv; i++)
54 				io_csum += p[i];
55 		}
56 
57 		p += rv;
58 		out += rv;
59 		count -= rv;
60 	}
61 
62 	return out;
63 }
64 
65 static __initdata char *message;
66 static void __init error(char *x)
67 {
68 	if (!message)
69 		message = x;
70 }
71 
72 #define panic_show_mem(fmt, ...) \
73 	({ show_mem(); panic(fmt, ##__VA_ARGS__); })
74 
75 /* link hash */
76 
77 #define N_ALIGN(len) ((((len) + 1) & ~3) + 2)
78 
79 static __initdata struct hash {
80 	int ino, minor, major;
81 	umode_t mode;
82 	struct hash *next;
83 	char name[N_ALIGN(PATH_MAX)];
84 } *head[32];
85 static __initdata bool hardlink_seen;
86 
87 static inline int hash(int major, int minor, int ino)
88 {
89 	unsigned long tmp = ino + minor + (major << 3);
90 	tmp += tmp >> 5;
91 	return tmp & 31;
92 }
93 
94 static char __init *find_link(int major, int minor, int ino,
95 			      umode_t mode, char *name)
96 {
97 	struct hash **p, *q;
98 	for (p = head + hash(major, minor, ino); *p; p = &(*p)->next) {
99 		if ((*p)->ino != ino)
100 			continue;
101 		if ((*p)->minor != minor)
102 			continue;
103 		if ((*p)->major != major)
104 			continue;
105 		if (((*p)->mode ^ mode) & S_IFMT)
106 			continue;
107 		return (*p)->name;
108 	}
109 	q = kmalloc_obj(struct hash);
110 	if (!q)
111 		panic_show_mem("can't allocate link hash entry");
112 	q->major = major;
113 	q->minor = minor;
114 	q->ino = ino;
115 	q->mode = mode;
116 	strscpy(q->name, name);
117 	q->next = NULL;
118 	*p = q;
119 	hardlink_seen = true;
120 	return NULL;
121 }
122 
123 static void __init free_hash(void)
124 {
125 	struct hash **p, *q;
126 	for (p = head; hardlink_seen && p < head + 32; p++) {
127 		while (*p) {
128 			q = *p;
129 			*p = q->next;
130 			kfree(q);
131 		}
132 	}
133 	hardlink_seen = false;
134 }
135 
136 #ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
137 static void __init do_utime(char *filename, time64_t mtime)
138 {
139 	struct timespec64 t[2] = { { .tv_sec = mtime }, { .tv_sec = mtime } };
140 	init_utimes(filename, t);
141 }
142 
143 static void __init do_utime_path(const struct path *path, time64_t mtime)
144 {
145 	struct timespec64 t[2] = { { .tv_sec = mtime }, { .tv_sec = mtime } };
146 	vfs_utimes(path, t);
147 }
148 
149 static __initdata LIST_HEAD(dir_list);
150 struct dir_entry {
151 	struct list_head list;
152 	time64_t mtime;
153 	char name[];
154 };
155 
156 static void __init dir_add(const char *name, size_t nlen, time64_t mtime)
157 {
158 	struct dir_entry *de;
159 
160 	de = kmalloc_flex(*de, name, nlen);
161 	if (!de)
162 		panic_show_mem("can't allocate dir_entry buffer");
163 	INIT_LIST_HEAD(&de->list);
164 	strscpy(de->name, name, nlen);
165 	de->mtime = mtime;
166 	list_add(&de->list, &dir_list);
167 }
168 
169 static void __init dir_utime(void)
170 {
171 	struct dir_entry *de, *tmp;
172 	list_for_each_entry_safe(de, tmp, &dir_list, list) {
173 		list_del(&de->list);
174 		do_utime(de->name, de->mtime);
175 		kfree(de);
176 	}
177 }
178 #else
179 static void __init do_utime(char *filename, time64_t mtime) {}
180 static void __init do_utime_path(const struct path *path, time64_t mtime) {}
181 static void __init dir_add(const char *name, size_t nlen, time64_t mtime) {}
182 static void __init dir_utime(void) {}
183 #endif
184 
185 static __initdata time64_t mtime;
186 
187 /* cpio header parsing */
188 
189 static __initdata unsigned long ino, major, minor, nlink;
190 static __initdata umode_t mode;
191 static __initdata unsigned long body_len, name_len;
192 static __initdata uid_t uid;
193 static __initdata gid_t gid;
194 static __initdata unsigned rdev;
195 static __initdata u32 hdr_csum;
196 
197 static int __init parse_header(char *s)
198 {
199 	__be32 header[13];
200 	int ret;
201 
202 	ret = hex2bin((u8 *)header, s + 6, sizeof(header));
203 	if (ret) {
204 		error("damaged header");
205 		return ret;
206 	}
207 
208 	ino = be32_to_cpu(header[0]);
209 	mode = be32_to_cpu(header[1]);
210 	uid = be32_to_cpu(header[2]);
211 	gid = be32_to_cpu(header[3]);
212 	nlink = be32_to_cpu(header[4]);
213 	mtime = be32_to_cpu(header[5]); /* breaks in y2106 */
214 	body_len = be32_to_cpu(header[6]);
215 	major = be32_to_cpu(header[7]);
216 	minor = be32_to_cpu(header[8]);
217 	rdev = new_encode_dev(MKDEV(be32_to_cpu(header[9]), be32_to_cpu(header[10])));
218 	name_len = be32_to_cpu(header[11]);
219 	hdr_csum = be32_to_cpu(header[12]);
220 	return 0;
221 }
222 
223 /* Finite-state machine */
224 
225 static __initdata enum state {
226 	Start,
227 	Collect,
228 	GotHeader,
229 	SkipIt,
230 	GotName,
231 	CopyFile,
232 	GotSymlink,
233 	Reset
234 } state, next_state;
235 
236 static __initdata char *victim;
237 static unsigned long byte_count __initdata;
238 static __initdata loff_t this_header, next_header;
239 
240 static inline void __init eat(unsigned n)
241 {
242 	victim += n;
243 	this_header += n;
244 	byte_count -= n;
245 }
246 
247 static __initdata char *collected;
248 static long remains __initdata;
249 static __initdata char *collect;
250 
251 static void __init read_into(char *buf, unsigned size, enum state next)
252 {
253 	if (byte_count >= size) {
254 		collected = victim;
255 		eat(size);
256 		state = next;
257 	} else {
258 		collect = collected = buf;
259 		remains = size;
260 		next_state = next;
261 		state = Collect;
262 	}
263 }
264 
265 static __initdata char *header_buf, *symlink_buf, *name_buf;
266 
267 static int __init do_start(void)
268 {
269 	read_into(header_buf, CPIO_HDRLEN, GotHeader);
270 	return 0;
271 }
272 
273 static int __init do_collect(void)
274 {
275 	unsigned long n = remains;
276 	if (byte_count < n)
277 		n = byte_count;
278 	memcpy(collect, victim, n);
279 	eat(n);
280 	collect += n;
281 	if ((remains -= n) != 0)
282 		return 1;
283 	state = next_state;
284 	return 0;
285 }
286 
287 static int __init do_header(void)
288 {
289 	if (!memcmp(collected, "070701", 6)) {
290 		csum_present = false;
291 	} else if (!memcmp(collected, "070702", 6)) {
292 		csum_present = true;
293 	} else {
294 		if (memcmp(collected, "070707", 6) == 0)
295 			error("incorrect cpio method used: use -H newc option");
296 		else
297 			error("no cpio magic");
298 		return 1;
299 	}
300 	if (parse_header(collected))
301 		return 1;
302 	next_header = this_header + N_ALIGN(name_len) + body_len;
303 	next_header = (next_header + 3) & ~3;
304 	state = SkipIt;
305 	if (name_len <= 0 || name_len > PATH_MAX)
306 		return 0;
307 	if (S_ISLNK(mode)) {
308 		if (body_len > PATH_MAX)
309 			return 0;
310 		collect = collected = symlink_buf;
311 		remains = N_ALIGN(name_len) + body_len;
312 		next_state = GotSymlink;
313 		state = Collect;
314 		return 0;
315 	}
316 	if (S_ISREG(mode) || !body_len)
317 		read_into(name_buf, N_ALIGN(name_len), GotName);
318 	return 0;
319 }
320 
321 static int __init do_skip(void)
322 {
323 	if (this_header + byte_count < next_header) {
324 		eat(byte_count);
325 		return 1;
326 	} else {
327 		eat(next_header - this_header);
328 		state = next_state;
329 		return 0;
330 	}
331 }
332 
333 static int __init do_reset(void)
334 {
335 	while (byte_count && *victim == '\0')
336 		eat(1);
337 	if (byte_count && (this_header & 3))
338 		error("broken padding");
339 	return 1;
340 }
341 
342 static void __init clean_path(char *path, umode_t fmode)
343 {
344 	struct kstat st;
345 
346 	if (!init_stat(path, &st, AT_SYMLINK_NOFOLLOW) &&
347 	    (st.mode ^ fmode) & S_IFMT) {
348 		if (S_ISDIR(st.mode))
349 			init_rmdir(path);
350 		else
351 			init_unlink(path);
352 	}
353 }
354 
355 static int __init maybe_link(void)
356 {
357 	if (nlink >= 2) {
358 		char *old = find_link(major, minor, ino, mode, collected);
359 		if (old) {
360 			clean_path(collected, 0);
361 			return (init_link(old, collected) < 0) ? -1 : 1;
362 		}
363 	}
364 	return 0;
365 }
366 
367 static __initdata struct file *wfile;
368 static __initdata loff_t wfile_pos;
369 
370 static int __init do_name(void)
371 {
372 	state = SkipIt;
373 	next_state = Reset;
374 
375 	/* name_len > 0 && name_len <= PATH_MAX checked in do_header */
376 	if (collected[name_len - 1] != '\0') {
377 		pr_err("initramfs name without nulterm: %.*s\n",
378 		       (int)name_len, collected);
379 		error("malformed archive");
380 		return 1;
381 	}
382 
383 	if (strcmp(collected, "TRAILER!!!") == 0) {
384 		free_hash();
385 		return 0;
386 	}
387 	clean_path(collected, mode);
388 	if (S_ISREG(mode)) {
389 		int ml = maybe_link();
390 		if (ml >= 0) {
391 			int openflags = O_WRONLY|O_CREAT|O_LARGEFILE;
392 			if (ml != 1)
393 				openflags |= O_TRUNC;
394 			wfile = filp_open(collected, openflags, mode);
395 			if (IS_ERR(wfile))
396 				return 0;
397 			wfile_pos = 0;
398 			io_csum = 0;
399 
400 			vfs_fchown(wfile, uid, gid);
401 			vfs_fchmod(wfile, mode);
402 			if (body_len)
403 				vfs_truncate(&wfile->f_path, body_len);
404 			state = CopyFile;
405 		}
406 	} else if (S_ISDIR(mode)) {
407 		init_mkdir(collected, mode);
408 		init_chown(collected, uid, gid, 0);
409 		init_chmod(collected, mode);
410 		dir_add(collected, name_len, mtime);
411 	} else if (S_ISBLK(mode) || S_ISCHR(mode) ||
412 		   S_ISFIFO(mode) || S_ISSOCK(mode)) {
413 		if (maybe_link() == 0) {
414 			init_mknod(collected, mode, rdev);
415 			init_chown(collected, uid, gid, 0);
416 			init_chmod(collected, mode);
417 			do_utime(collected, mtime);
418 		}
419 	}
420 	return 0;
421 }
422 
423 static int __init do_copy(void)
424 {
425 	if (byte_count >= body_len) {
426 		if (xwrite(wfile, victim, body_len, &wfile_pos) != body_len)
427 			error("write error");
428 
429 		do_utime_path(&wfile->f_path, mtime);
430 		fput(wfile);
431 		if (csum_present && io_csum != hdr_csum)
432 			error("bad data checksum");
433 		eat(body_len);
434 		state = SkipIt;
435 		return 0;
436 	} else {
437 		if (xwrite(wfile, victim, byte_count, &wfile_pos) != byte_count)
438 			error("write error");
439 		body_len -= byte_count;
440 		eat(byte_count);
441 		return 1;
442 	}
443 }
444 
445 static int __init do_symlink(void)
446 {
447 	if (collected[name_len - 1] != '\0') {
448 		pr_err("initramfs symlink without nulterm: %.*s\n",
449 		       (int)name_len, collected);
450 		error("malformed archive");
451 		return 1;
452 	}
453 	collected[N_ALIGN(name_len) + body_len] = '\0';
454 	clean_path(collected, 0);
455 	init_symlink(collected + N_ALIGN(name_len), collected);
456 	init_chown(collected, uid, gid, AT_SYMLINK_NOFOLLOW);
457 	do_utime(collected, mtime);
458 	state = SkipIt;
459 	next_state = Reset;
460 	return 0;
461 }
462 
463 static __initdata int (*actions[])(void) = {
464 	[Start]		= do_start,
465 	[Collect]	= do_collect,
466 	[GotHeader]	= do_header,
467 	[SkipIt]	= do_skip,
468 	[GotName]	= do_name,
469 	[CopyFile]	= do_copy,
470 	[GotSymlink]	= do_symlink,
471 	[Reset]		= do_reset,
472 };
473 
474 static long __init write_buffer(char *buf, unsigned long len)
475 {
476 	byte_count = len;
477 	victim = buf;
478 
479 	while (!actions[state]())
480 		;
481 	return len - byte_count;
482 }
483 
484 static long __init flush_buffer(void *bufv, unsigned long len)
485 {
486 	char *buf = bufv;
487 	long written;
488 	long origLen = len;
489 	if (message)
490 		return -1;
491 	while ((written = write_buffer(buf, len)) < len && !message) {
492 		char c = buf[written];
493 		if (c == '0') {
494 			buf += written;
495 			len -= written;
496 			state = Start;
497 		} else if (c == 0) {
498 			buf += written;
499 			len -= written;
500 			state = Reset;
501 		} else
502 			error("junk within compressed archive");
503 	}
504 	return origLen;
505 }
506 
507 static unsigned long my_inptr __initdata; /* index of next byte to be processed in inbuf */
508 
509 #include <linux/decompress/generic.h>
510 
511 /**
512  * unpack_to_rootfs - decompress and extract an initramfs archive
513  * @buf: input initramfs archive to extract
514  * @len: length of initramfs data to process
515  *
516  * Returns: NULL for success or an error message string
517  *
518  * This symbol shouldn't be used externally. It's available for unit tests.
519  */
520 char * __init unpack_to_rootfs(char *buf, unsigned long len)
521 {
522 	long written;
523 	decompress_fn decompress;
524 	const char *compress_name;
525 	struct {
526 		char header[CPIO_HDRLEN];
527 		char symlink[PATH_MAX + N_ALIGN(PATH_MAX) + 1];
528 		char name[N_ALIGN(PATH_MAX)];
529 	} *bufs = kmalloc_obj(*bufs);
530 
531 	if (!bufs)
532 		panic_show_mem("can't allocate buffers");
533 
534 	header_buf = bufs->header;
535 	symlink_buf = bufs->symlink;
536 	name_buf = bufs->name;
537 
538 	state = Start;
539 	this_header = 0;
540 	message = NULL;
541 	while (!message && len) {
542 		loff_t saved_offset = this_header;
543 		if (*buf == '0' && !(this_header & 3)) {
544 			state = Start;
545 			written = write_buffer(buf, len);
546 			buf += written;
547 			len -= written;
548 			continue;
549 		}
550 		if (!*buf) {
551 			buf++;
552 			len--;
553 			this_header++;
554 			continue;
555 		}
556 		this_header = 0;
557 		decompress = decompress_method(buf, len, &compress_name);
558 		pr_debug("Detected %s compressed data\n", compress_name);
559 		if (decompress) {
560 			int res = decompress(buf, len, NULL, flush_buffer, NULL,
561 				   &my_inptr, error);
562 			if (res)
563 				error("decompressor failed");
564 		} else if (compress_name) {
565 			pr_err("compression method %s not configured\n",
566 			       compress_name);
567 			error("decompressor failed");
568 		} else
569 			error("invalid magic at start of compressed archive");
570 		if (state != Reset)
571 			error("junk at the end of compressed archive");
572 		this_header = saved_offset + my_inptr;
573 		buf += my_inptr;
574 		len -= my_inptr;
575 	}
576 	dir_utime();
577 	/* free any hardlink state collected without optional TRAILER!!! */
578 	free_hash();
579 	kfree(bufs);
580 	return message;
581 }
582 
583 static int __initdata do_retain_initrd;
584 
585 static int __init retain_initrd_param(char *str)
586 {
587 	if (*str)
588 		return 0;
589 	do_retain_initrd = 1;
590 	return 1;
591 }
592 __setup("retain_initrd", retain_initrd_param);
593 
594 #ifdef CONFIG_ARCH_HAS_KEEPINITRD
595 static int __init keepinitrd_setup(char *__unused)
596 {
597 	do_retain_initrd = 1;
598 	return 1;
599 }
600 __setup("keepinitrd", keepinitrd_setup);
601 #endif
602 
603 static bool __initdata initramfs_async = true;
604 static int __init initramfs_async_setup(char *str)
605 {
606 	return kstrtobool(str, &initramfs_async) == 0;
607 }
608 __setup("initramfs_async=", initramfs_async_setup);
609 
610 extern char __initramfs_start[];
611 extern unsigned long __initramfs_size;
612 #include <linux/initrd.h>
613 #include <linux/kexec.h>
614 
615 static BIN_ATTR(initrd, 0440, sysfs_bin_attr_simple_read, NULL, 0);
616 
617 void __init reserve_initrd_mem(void)
618 {
619 	phys_addr_t start;
620 	unsigned long size;
621 
622 	/* Ignore the virtual address computed during device tree parsing */
623 	initrd_start = initrd_end = 0;
624 
625 	if (!phys_initrd_size)
626 		return;
627 	/*
628 	 * Round the memory region to page boundaries as per free_initrd_mem()
629 	 * This allows us to detect whether the pages overlapping the initrd
630 	 * are in use, but more importantly, reserves the entire set of pages
631 	 * as we don't want these pages allocated for other purposes.
632 	 */
633 	start = round_down(phys_initrd_start, PAGE_SIZE);
634 	size = phys_initrd_size + (phys_initrd_start - start);
635 	size = round_up(size, PAGE_SIZE);
636 
637 	if (!memblock_is_region_memory(start, size)) {
638 		pr_err("INITRD: 0x%08llx+0x%08lx is not a memory region",
639 		       (u64)start, size);
640 		goto disable;
641 	}
642 
643 	if (memblock_is_region_reserved(start, size)) {
644 		pr_err("INITRD: 0x%08llx+0x%08lx overlaps in-use memory region\n",
645 		       (u64)start, size);
646 		goto disable;
647 	}
648 
649 	memblock_reserve(start, size);
650 	/* Now convert initrd to virtual addresses */
651 	initrd_start = (unsigned long)__va(phys_initrd_start);
652 	initrd_end = initrd_start + phys_initrd_size;
653 	initrd_below_start_ok = 1;
654 
655 	return;
656 disable:
657 	pr_cont(" - disabling initrd\n");
658 	initrd_start = 0;
659 	initrd_end = 0;
660 }
661 
662 void __weak __init free_initrd_mem(unsigned long start, unsigned long end)
663 {
664 	free_reserved_area((void *)start, (void *)end, POISON_FREE_INITMEM,
665 			"initrd");
666 }
667 
668 #ifdef CONFIG_CRASH_RESERVE
669 static bool __init kexec_free_initrd(void)
670 {
671 	unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
672 	unsigned long crashk_end   = (unsigned long)__va(crashk_res.end);
673 
674 	/*
675 	 * If the initrd region is overlapped with crashkernel reserved region,
676 	 * free only memory that is not part of crashkernel region.
677 	 */
678 	if (initrd_start >= crashk_end || initrd_end <= crashk_start)
679 		return false;
680 
681 	/*
682 	 * Initialize initrd memory region since the kexec boot does not do.
683 	 */
684 	memset((void *)initrd_start, 0, initrd_end - initrd_start);
685 	if (initrd_start < crashk_start)
686 		free_initrd_mem(initrd_start, crashk_start);
687 	if (initrd_end > crashk_end)
688 		free_initrd_mem(crashk_end, initrd_end);
689 	return true;
690 }
691 #else
692 static inline bool kexec_free_initrd(void)
693 {
694 	return false;
695 }
696 #endif /* CONFIG_KEXEC_CORE */
697 
698 #ifdef CONFIG_BLK_DEV_RAM
699 static void __init populate_initrd_image(char *err)
700 {
701 	ssize_t written;
702 	struct file *file;
703 	loff_t pos = 0;
704 
705 	printk(KERN_INFO "rootfs image is not initramfs (%s); looks like an initrd\n",
706 			err);
707 	file = filp_open("/initrd.image", O_WRONLY|O_CREAT|O_LARGEFILE, 0700);
708 	if (IS_ERR(file))
709 		return;
710 
711 	written = xwrite(file, (char *)initrd_start, initrd_end - initrd_start,
712 			&pos);
713 	if (written != initrd_end - initrd_start)
714 		pr_err("/initrd.image: incomplete write (%zd != %ld)\n",
715 		       written, initrd_end - initrd_start);
716 	fput(file);
717 }
718 #endif /* CONFIG_BLK_DEV_RAM */
719 
720 static void __init unpack_initramfs(async_cookie_t cookie)
721 {
722 	/* Load the built in initramfs */
723 	char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
724 	if (err)
725 		panic_show_mem("%s", err); /* Failed to decompress INTERNAL initramfs */
726 
727 	if (!initrd_start || IS_ENABLED(CONFIG_INITRAMFS_FORCE))
728 		return;
729 
730 	if (IS_ENABLED(CONFIG_BLK_DEV_RAM))
731 		printk(KERN_INFO "Trying to unpack rootfs image as initramfs...\n");
732 	else
733 		printk(KERN_INFO "Unpacking initramfs...\n");
734 
735 	err = unpack_to_rootfs((char *)initrd_start, initrd_end - initrd_start);
736 	if (err) {
737 #ifdef CONFIG_BLK_DEV_RAM
738 		populate_initrd_image(err);
739 #else
740 		printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
741 #endif
742 	}
743 }
744 
745 static void __init do_populate_rootfs(void *unused, async_cookie_t cookie)
746 {
747 	scoped_with_init_fs() {
748 		unpack_initramfs(cookie);
749 		security_initramfs_populated();
750 	}
751 
752 	/*
753 	 * If the initrd region is overlapped with crashkernel reserved region,
754 	 * free only memory that is not part of crashkernel region.
755 	 */
756 	if (!do_retain_initrd && initrd_start && !kexec_free_initrd()) {
757 		free_initrd_mem(initrd_start, initrd_end);
758 	} else if (do_retain_initrd && initrd_start) {
759 		bin_attr_initrd.size = initrd_end - initrd_start;
760 		bin_attr_initrd.private = (void *)initrd_start;
761 		if (sysfs_create_bin_file(firmware_kobj, &bin_attr_initrd))
762 			pr_err("Failed to create initrd sysfs file");
763 	}
764 	initrd_start = 0;
765 	initrd_end = 0;
766 
767 	init_flush_fput();
768 }
769 
770 static ASYNC_DOMAIN_EXCLUSIVE(initramfs_domain);
771 static async_cookie_t initramfs_cookie;
772 
773 void wait_for_initramfs(void)
774 {
775 	if (!initramfs_cookie) {
776 		/*
777 		 * Something before rootfs_initcall wants to access
778 		 * the filesystem/initramfs. Probably a bug. Make a
779 		 * note, avoid deadlocking the machine, and let the
780 		 * caller's access fail as it used to.
781 		 */
782 		pr_warn_once("wait_for_initramfs() called before rootfs_initcalls\n");
783 		return;
784 	}
785 	async_synchronize_cookie_domain(initramfs_cookie + 1, &initramfs_domain);
786 }
787 EXPORT_SYMBOL_GPL(wait_for_initramfs);
788 
789 static int __init populate_rootfs(void)
790 {
791 	initramfs_cookie = async_schedule_domain(do_populate_rootfs, NULL,
792 						 &initramfs_domain);
793 	usermodehelper_enable();
794 	if (!initramfs_async)
795 		wait_for_initramfs();
796 	return 0;
797 }
798 rootfs_initcall(populate_rootfs);
799