xref: /openbmc/linux/init/initramfs.c (revision 32e47502)
1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/init.h>
3 #include <linux/async.h>
4 #include <linux/fs.h>
5 #include <linux/slab.h>
6 #include <linux/types.h>
7 #include <linux/fcntl.h>
8 #include <linux/delay.h>
9 #include <linux/string.h>
10 #include <linux/dirent.h>
11 #include <linux/syscalls.h>
12 #include <linux/utime.h>
13 #include <linux/file.h>
14 #include <linux/kstrtox.h>
15 #include <linux/memblock.h>
16 #include <linux/mm.h>
17 #include <linux/namei.h>
18 #include <linux/init_syscalls.h>
19 #include <linux/task_work.h>
20 #include <linux/umh.h>
21 
22 static __initdata bool csum_present;
23 static __initdata u32 io_csum;
24 
xwrite(struct file * file,const unsigned char * p,size_t count,loff_t * pos)25 static ssize_t __init xwrite(struct file *file, const unsigned char *p,
26 		size_t count, loff_t *pos)
27 {
28 	ssize_t out = 0;
29 
30 	/* sys_write only can write MAX_RW_COUNT aka 2G-4K bytes at most */
31 	while (count) {
32 		ssize_t rv = kernel_write(file, p, count, pos);
33 
34 		if (rv < 0) {
35 			if (rv == -EINTR || rv == -EAGAIN)
36 				continue;
37 			return out ? out : rv;
38 		} else if (rv == 0)
39 			break;
40 
41 		if (csum_present) {
42 			ssize_t i;
43 
44 			for (i = 0; i < rv; i++)
45 				io_csum += p[i];
46 		}
47 
48 		p += rv;
49 		out += rv;
50 		count -= rv;
51 	}
52 
53 	return out;
54 }
55 
56 static __initdata char *message;
error(char * x)57 static void __init error(char *x)
58 {
59 	if (!message)
60 		message = x;
61 }
62 
63 #define panic_show_mem(fmt, ...) \
64 	({ show_mem(); panic(fmt, ##__VA_ARGS__); })
65 
66 /* link hash */
67 
68 #define N_ALIGN(len) ((((len) + 1) & ~3) + 2)
69 
70 static __initdata struct hash {
71 	int ino, minor, major;
72 	umode_t mode;
73 	struct hash *next;
74 	char name[N_ALIGN(PATH_MAX)];
75 } *head[32];
76 
hash(int major,int minor,int ino)77 static inline int hash(int major, int minor, int ino)
78 {
79 	unsigned long tmp = ino + minor + (major << 3);
80 	tmp += tmp >> 5;
81 	return tmp & 31;
82 }
83 
find_link(int major,int minor,int ino,umode_t mode,char * name)84 static char __init *find_link(int major, int minor, int ino,
85 			      umode_t mode, char *name)
86 {
87 	struct hash **p, *q;
88 	for (p = head + hash(major, minor, ino); *p; p = &(*p)->next) {
89 		if ((*p)->ino != ino)
90 			continue;
91 		if ((*p)->minor != minor)
92 			continue;
93 		if ((*p)->major != major)
94 			continue;
95 		if (((*p)->mode ^ mode) & S_IFMT)
96 			continue;
97 		return (*p)->name;
98 	}
99 	q = kmalloc(sizeof(struct hash), GFP_KERNEL);
100 	if (!q)
101 		panic_show_mem("can't allocate link hash entry");
102 	q->major = major;
103 	q->minor = minor;
104 	q->ino = ino;
105 	q->mode = mode;
106 	strcpy(q->name, name);
107 	q->next = NULL;
108 	*p = q;
109 	return NULL;
110 }
111 
free_hash(void)112 static void __init free_hash(void)
113 {
114 	struct hash **p, *q;
115 	for (p = head; p < head + 32; p++) {
116 		while (*p) {
117 			q = *p;
118 			*p = q->next;
119 			kfree(q);
120 		}
121 	}
122 }
123 
124 #ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
do_utime(char * filename,time64_t mtime)125 static void __init do_utime(char *filename, time64_t mtime)
126 {
127 	struct timespec64 t[2] = { { .tv_sec = mtime }, { .tv_sec = mtime } };
128 	init_utimes(filename, t);
129 }
130 
do_utime_path(const struct path * path,time64_t mtime)131 static void __init do_utime_path(const struct path *path, time64_t mtime)
132 {
133 	struct timespec64 t[2] = { { .tv_sec = mtime }, { .tv_sec = mtime } };
134 	vfs_utimes(path, t);
135 }
136 
137 static __initdata LIST_HEAD(dir_list);
138 struct dir_entry {
139 	struct list_head list;
140 	time64_t mtime;
141 	char name[];
142 };
143 
dir_add(const char * name,time64_t mtime)144 static void __init dir_add(const char *name, time64_t mtime)
145 {
146 	size_t nlen = strlen(name) + 1;
147 	struct dir_entry *de;
148 
149 	de = kmalloc(sizeof(struct dir_entry) + nlen, GFP_KERNEL);
150 	if (!de)
151 		panic_show_mem("can't allocate dir_entry buffer");
152 	INIT_LIST_HEAD(&de->list);
153 	strscpy(de->name, name, nlen);
154 	de->mtime = mtime;
155 	list_add(&de->list, &dir_list);
156 }
157 
dir_utime(void)158 static void __init dir_utime(void)
159 {
160 	struct dir_entry *de, *tmp;
161 	list_for_each_entry_safe(de, tmp, &dir_list, list) {
162 		list_del(&de->list);
163 		do_utime(de->name, de->mtime);
164 		kfree(de);
165 	}
166 }
167 #else
do_utime(char * filename,time64_t mtime)168 static void __init do_utime(char *filename, time64_t mtime) {}
do_utime_path(const struct path * path,time64_t mtime)169 static void __init do_utime_path(const struct path *path, time64_t mtime) {}
dir_add(const char * name,time64_t mtime)170 static void __init dir_add(const char *name, time64_t mtime) {}
dir_utime(void)171 static void __init dir_utime(void) {}
172 #endif
173 
174 static __initdata time64_t mtime;
175 
176 /* cpio header parsing */
177 
178 static __initdata unsigned long ino, major, minor, nlink;
179 static __initdata umode_t mode;
180 static __initdata unsigned long body_len, name_len;
181 static __initdata uid_t uid;
182 static __initdata gid_t gid;
183 static __initdata unsigned rdev;
184 static __initdata u32 hdr_csum;
185 
parse_header(char * s)186 static void __init parse_header(char *s)
187 {
188 	unsigned long parsed[13];
189 	char buf[9];
190 	int i;
191 
192 	buf[8] = '\0';
193 	for (i = 0, s += 6; i < 13; i++, s += 8) {
194 		memcpy(buf, s, 8);
195 		parsed[i] = simple_strtoul(buf, NULL, 16);
196 	}
197 	ino = parsed[0];
198 	mode = parsed[1];
199 	uid = parsed[2];
200 	gid = parsed[3];
201 	nlink = parsed[4];
202 	mtime = parsed[5]; /* breaks in y2106 */
203 	body_len = parsed[6];
204 	major = parsed[7];
205 	minor = parsed[8];
206 	rdev = new_encode_dev(MKDEV(parsed[9], parsed[10]));
207 	name_len = parsed[11];
208 	hdr_csum = parsed[12];
209 }
210 
211 /* FSM */
212 
213 static __initdata enum state {
214 	Start,
215 	Collect,
216 	GotHeader,
217 	SkipIt,
218 	GotName,
219 	CopyFile,
220 	GotSymlink,
221 	Reset
222 } state, next_state;
223 
224 static __initdata char *victim;
225 static unsigned long byte_count __initdata;
226 static __initdata loff_t this_header, next_header;
227 
eat(unsigned n)228 static inline void __init eat(unsigned n)
229 {
230 	victim += n;
231 	this_header += n;
232 	byte_count -= n;
233 }
234 
235 static __initdata char *collected;
236 static long remains __initdata;
237 static __initdata char *collect;
238 
read_into(char * buf,unsigned size,enum state next)239 static void __init read_into(char *buf, unsigned size, enum state next)
240 {
241 	if (byte_count >= size) {
242 		collected = victim;
243 		eat(size);
244 		state = next;
245 	} else {
246 		collect = collected = buf;
247 		remains = size;
248 		next_state = next;
249 		state = Collect;
250 	}
251 }
252 
253 static __initdata char *header_buf, *symlink_buf, *name_buf;
254 
do_start(void)255 static int __init do_start(void)
256 {
257 	read_into(header_buf, 110, GotHeader);
258 	return 0;
259 }
260 
do_collect(void)261 static int __init do_collect(void)
262 {
263 	unsigned long n = remains;
264 	if (byte_count < n)
265 		n = byte_count;
266 	memcpy(collect, victim, n);
267 	eat(n);
268 	collect += n;
269 	if ((remains -= n) != 0)
270 		return 1;
271 	state = next_state;
272 	return 0;
273 }
274 
do_header(void)275 static int __init do_header(void)
276 {
277 	if (!memcmp(collected, "070701", 6)) {
278 		csum_present = false;
279 	} else if (!memcmp(collected, "070702", 6)) {
280 		csum_present = true;
281 	} else {
282 		if (memcmp(collected, "070707", 6) == 0)
283 			error("incorrect cpio method used: use -H newc option");
284 		else
285 			error("no cpio magic");
286 		return 1;
287 	}
288 	parse_header(collected);
289 	next_header = this_header + N_ALIGN(name_len) + body_len;
290 	next_header = (next_header + 3) & ~3;
291 	state = SkipIt;
292 	if (name_len <= 0 || name_len > PATH_MAX)
293 		return 0;
294 	if (S_ISLNK(mode)) {
295 		if (body_len > PATH_MAX)
296 			return 0;
297 		collect = collected = symlink_buf;
298 		remains = N_ALIGN(name_len) + body_len;
299 		next_state = GotSymlink;
300 		state = Collect;
301 		return 0;
302 	}
303 	if (S_ISREG(mode) || !body_len)
304 		read_into(name_buf, N_ALIGN(name_len), GotName);
305 	return 0;
306 }
307 
do_skip(void)308 static int __init do_skip(void)
309 {
310 	if (this_header + byte_count < next_header) {
311 		eat(byte_count);
312 		return 1;
313 	} else {
314 		eat(next_header - this_header);
315 		state = next_state;
316 		return 0;
317 	}
318 }
319 
do_reset(void)320 static int __init do_reset(void)
321 {
322 	while (byte_count && *victim == '\0')
323 		eat(1);
324 	if (byte_count && (this_header & 3))
325 		error("broken padding");
326 	return 1;
327 }
328 
clean_path(char * path,umode_t fmode)329 static void __init clean_path(char *path, umode_t fmode)
330 {
331 	struct kstat st;
332 
333 	if (!init_stat(path, &st, AT_SYMLINK_NOFOLLOW) &&
334 	    (st.mode ^ fmode) & S_IFMT) {
335 		if (S_ISDIR(st.mode))
336 			init_rmdir(path);
337 		else
338 			init_unlink(path);
339 	}
340 }
341 
maybe_link(void)342 static int __init maybe_link(void)
343 {
344 	if (nlink >= 2) {
345 		char *old = find_link(major, minor, ino, mode, collected);
346 		if (old) {
347 			clean_path(collected, 0);
348 			return (init_link(old, collected) < 0) ? -1 : 1;
349 		}
350 	}
351 	return 0;
352 }
353 
354 static __initdata struct file *wfile;
355 static __initdata loff_t wfile_pos;
356 
do_name(void)357 static int __init do_name(void)
358 {
359 	state = SkipIt;
360 	next_state = Reset;
361 	if (strcmp(collected, "TRAILER!!!") == 0) {
362 		free_hash();
363 		return 0;
364 	}
365 	clean_path(collected, mode);
366 	if (S_ISREG(mode)) {
367 		int ml = maybe_link();
368 		if (ml >= 0) {
369 			int openflags = O_WRONLY|O_CREAT;
370 			if (ml != 1)
371 				openflags |= O_TRUNC;
372 			wfile = filp_open(collected, openflags, mode);
373 			if (IS_ERR(wfile))
374 				return 0;
375 			wfile_pos = 0;
376 			io_csum = 0;
377 
378 			vfs_fchown(wfile, uid, gid);
379 			vfs_fchmod(wfile, mode);
380 			if (body_len)
381 				vfs_truncate(&wfile->f_path, body_len);
382 			state = CopyFile;
383 		}
384 	} else if (S_ISDIR(mode)) {
385 		init_mkdir(collected, mode);
386 		init_chown(collected, uid, gid, 0);
387 		init_chmod(collected, mode);
388 		dir_add(collected, mtime);
389 	} else if (S_ISBLK(mode) || S_ISCHR(mode) ||
390 		   S_ISFIFO(mode) || S_ISSOCK(mode)) {
391 		if (maybe_link() == 0) {
392 			init_mknod(collected, mode, rdev);
393 			init_chown(collected, uid, gid, 0);
394 			init_chmod(collected, mode);
395 			do_utime(collected, mtime);
396 		}
397 	}
398 	return 0;
399 }
400 
do_copy(void)401 static int __init do_copy(void)
402 {
403 	if (byte_count >= body_len) {
404 		if (xwrite(wfile, victim, body_len, &wfile_pos) != body_len)
405 			error("write error");
406 
407 		do_utime_path(&wfile->f_path, mtime);
408 		fput(wfile);
409 		if (csum_present && io_csum != hdr_csum)
410 			error("bad data checksum");
411 		eat(body_len);
412 		state = SkipIt;
413 		return 0;
414 	} else {
415 		if (xwrite(wfile, victim, byte_count, &wfile_pos) != byte_count)
416 			error("write error");
417 		body_len -= byte_count;
418 		eat(byte_count);
419 		return 1;
420 	}
421 }
422 
do_symlink(void)423 static int __init do_symlink(void)
424 {
425 	collected[N_ALIGN(name_len) + body_len] = '\0';
426 	clean_path(collected, 0);
427 	init_symlink(collected + N_ALIGN(name_len), collected);
428 	init_chown(collected, uid, gid, AT_SYMLINK_NOFOLLOW);
429 	do_utime(collected, mtime);
430 	state = SkipIt;
431 	next_state = Reset;
432 	return 0;
433 }
434 
435 static __initdata int (*actions[])(void) = {
436 	[Start]		= do_start,
437 	[Collect]	= do_collect,
438 	[GotHeader]	= do_header,
439 	[SkipIt]	= do_skip,
440 	[GotName]	= do_name,
441 	[CopyFile]	= do_copy,
442 	[GotSymlink]	= do_symlink,
443 	[Reset]		= do_reset,
444 };
445 
write_buffer(char * buf,unsigned long len)446 static long __init write_buffer(char *buf, unsigned long len)
447 {
448 	byte_count = len;
449 	victim = buf;
450 
451 	while (!actions[state]())
452 		;
453 	return len - byte_count;
454 }
455 
flush_buffer(void * bufv,unsigned long len)456 static long __init flush_buffer(void *bufv, unsigned long len)
457 {
458 	char *buf = bufv;
459 	long written;
460 	long origLen = len;
461 	if (message)
462 		return -1;
463 	while ((written = write_buffer(buf, len)) < len && !message) {
464 		char c = buf[written];
465 		if (c == '0') {
466 			buf += written;
467 			len -= written;
468 			state = Start;
469 		} else if (c == 0) {
470 			buf += written;
471 			len -= written;
472 			state = Reset;
473 		} else
474 			error("junk within compressed archive");
475 	}
476 	return origLen;
477 }
478 
479 static unsigned long my_inptr __initdata; /* index of next byte to be processed in inbuf */
480 
481 #include <linux/decompress/generic.h>
482 
unpack_to_rootfs(char * buf,unsigned long len)483 static char * __init unpack_to_rootfs(char *buf, unsigned long len)
484 {
485 	long written;
486 	decompress_fn decompress;
487 	const char *compress_name;
488 	static __initdata char msg_buf[64];
489 
490 	header_buf = kmalloc(110, GFP_KERNEL);
491 	symlink_buf = kmalloc(PATH_MAX + N_ALIGN(PATH_MAX) + 1, GFP_KERNEL);
492 	name_buf = kmalloc(N_ALIGN(PATH_MAX), GFP_KERNEL);
493 
494 	if (!header_buf || !symlink_buf || !name_buf)
495 		panic_show_mem("can't allocate buffers");
496 
497 	state = Start;
498 	this_header = 0;
499 	message = NULL;
500 	while (!message && len) {
501 		loff_t saved_offset = this_header;
502 		if (*buf == '0' && !(this_header & 3)) {
503 			state = Start;
504 			written = write_buffer(buf, len);
505 			buf += written;
506 			len -= written;
507 			continue;
508 		}
509 		if (!*buf) {
510 			buf++;
511 			len--;
512 			this_header++;
513 			continue;
514 		}
515 		this_header = 0;
516 		decompress = decompress_method(buf, len, &compress_name);
517 		pr_debug("Detected %s compressed data\n", compress_name);
518 		if (decompress) {
519 			int res = decompress(buf, len, NULL, flush_buffer, NULL,
520 				   &my_inptr, error);
521 			if (res)
522 				error("decompressor failed");
523 		} else if (compress_name) {
524 			if (!message) {
525 				snprintf(msg_buf, sizeof msg_buf,
526 					 "compression method %s not configured",
527 					 compress_name);
528 				message = msg_buf;
529 			}
530 		} else
531 			error("invalid magic at start of compressed archive");
532 		if (state != Reset)
533 			error("junk at the end of compressed archive");
534 		this_header = saved_offset + my_inptr;
535 		buf += my_inptr;
536 		len -= my_inptr;
537 	}
538 	dir_utime();
539 	kfree(name_buf);
540 	kfree(symlink_buf);
541 	kfree(header_buf);
542 	return message;
543 }
544 
545 static int __initdata do_retain_initrd;
546 
retain_initrd_param(char * str)547 static int __init retain_initrd_param(char *str)
548 {
549 	if (*str)
550 		return 0;
551 	do_retain_initrd = 1;
552 	return 1;
553 }
554 __setup("retain_initrd", retain_initrd_param);
555 
556 #ifdef CONFIG_ARCH_HAS_KEEPINITRD
keepinitrd_setup(char * __unused)557 static int __init keepinitrd_setup(char *__unused)
558 {
559 	do_retain_initrd = 1;
560 	return 1;
561 }
562 __setup("keepinitrd", keepinitrd_setup);
563 #endif
564 
565 static bool __initdata initramfs_async = true;
initramfs_async_setup(char * str)566 static int __init initramfs_async_setup(char *str)
567 {
568 	return kstrtobool(str, &initramfs_async) == 0;
569 }
570 __setup("initramfs_async=", initramfs_async_setup);
571 
572 extern char __initramfs_start[];
573 extern unsigned long __initramfs_size;
574 #include <linux/initrd.h>
575 #include <linux/kexec.h>
576 
reserve_initrd_mem(void)577 void __init reserve_initrd_mem(void)
578 {
579 	phys_addr_t start;
580 	unsigned long size;
581 
582 	/* Ignore the virtul address computed during device tree parsing */
583 	initrd_start = initrd_end = 0;
584 
585 	if (!phys_initrd_size)
586 		return;
587 	/*
588 	 * Round the memory region to page boundaries as per free_initrd_mem()
589 	 * This allows us to detect whether the pages overlapping the initrd
590 	 * are in use, but more importantly, reserves the entire set of pages
591 	 * as we don't want these pages allocated for other purposes.
592 	 */
593 	start = round_down(phys_initrd_start, PAGE_SIZE);
594 	size = phys_initrd_size + (phys_initrd_start - start);
595 	size = round_up(size, PAGE_SIZE);
596 
597 	if (!memblock_is_region_memory(start, size)) {
598 		pr_err("INITRD: 0x%08llx+0x%08lx is not a memory region",
599 		       (u64)start, size);
600 		goto disable;
601 	}
602 
603 	if (memblock_is_region_reserved(start, size)) {
604 		pr_err("INITRD: 0x%08llx+0x%08lx overlaps in-use memory region\n",
605 		       (u64)start, size);
606 		goto disable;
607 	}
608 
609 	memblock_reserve(start, size);
610 	/* Now convert initrd to virtual addresses */
611 	initrd_start = (unsigned long)__va(phys_initrd_start);
612 	initrd_end = initrd_start + phys_initrd_size;
613 	initrd_below_start_ok = 1;
614 
615 	return;
616 disable:
617 	pr_cont(" - disabling initrd\n");
618 	initrd_start = 0;
619 	initrd_end = 0;
620 }
621 
free_initrd_mem(unsigned long start,unsigned long end)622 void __weak __init free_initrd_mem(unsigned long start, unsigned long end)
623 {
624 #ifdef CONFIG_ARCH_KEEP_MEMBLOCK
625 	unsigned long aligned_start = ALIGN_DOWN(start, PAGE_SIZE);
626 	unsigned long aligned_end = ALIGN(end, PAGE_SIZE);
627 
628 	memblock_free((void *)aligned_start, aligned_end - aligned_start);
629 #endif
630 
631 	free_reserved_area((void *)start, (void *)end, POISON_FREE_INITMEM,
632 			"initrd");
633 }
634 
635 #ifdef CONFIG_KEXEC_CORE
kexec_free_initrd(void)636 static bool __init kexec_free_initrd(void)
637 {
638 	unsigned long crashk_start = (unsigned long)__va(crashk_res.start);
639 	unsigned long crashk_end   = (unsigned long)__va(crashk_res.end);
640 
641 	/*
642 	 * If the initrd region is overlapped with crashkernel reserved region,
643 	 * free only memory that is not part of crashkernel region.
644 	 */
645 	if (initrd_start >= crashk_end || initrd_end <= crashk_start)
646 		return false;
647 
648 	/*
649 	 * Initialize initrd memory region since the kexec boot does not do.
650 	 */
651 	memset((void *)initrd_start, 0, initrd_end - initrd_start);
652 	if (initrd_start < crashk_start)
653 		free_initrd_mem(initrd_start, crashk_start);
654 	if (initrd_end > crashk_end)
655 		free_initrd_mem(crashk_end, initrd_end);
656 	return true;
657 }
658 #else
kexec_free_initrd(void)659 static inline bool kexec_free_initrd(void)
660 {
661 	return false;
662 }
663 #endif /* CONFIG_KEXEC_CORE */
664 
665 #ifdef CONFIG_BLK_DEV_RAM
populate_initrd_image(char * err)666 static void __init populate_initrd_image(char *err)
667 {
668 	ssize_t written;
669 	struct file *file;
670 	loff_t pos = 0;
671 
672 	unpack_to_rootfs(__initramfs_start, __initramfs_size);
673 
674 	printk(KERN_INFO "rootfs image is not initramfs (%s); looks like an initrd\n",
675 			err);
676 	file = filp_open("/initrd.image", O_WRONLY|O_CREAT|O_LARGEFILE, 0700);
677 	if (IS_ERR(file))
678 		return;
679 
680 	written = xwrite(file, (char *)initrd_start, initrd_end - initrd_start,
681 			&pos);
682 	if (written != initrd_end - initrd_start)
683 		pr_err("/initrd.image: incomplete write (%zd != %ld)\n",
684 		       written, initrd_end - initrd_start);
685 	fput(file);
686 }
687 #endif /* CONFIG_BLK_DEV_RAM */
688 
do_populate_rootfs(void * unused,async_cookie_t cookie)689 static void __init do_populate_rootfs(void *unused, async_cookie_t cookie)
690 {
691 	/* Load the built in initramfs */
692 	char *err = unpack_to_rootfs(__initramfs_start, __initramfs_size);
693 	if (err)
694 		panic_show_mem("%s", err); /* Failed to decompress INTERNAL initramfs */
695 
696 	if (!initrd_start || IS_ENABLED(CONFIG_INITRAMFS_FORCE))
697 		goto done;
698 
699 	if (IS_ENABLED(CONFIG_BLK_DEV_RAM))
700 		printk(KERN_INFO "Trying to unpack rootfs image as initramfs...\n");
701 	else
702 		printk(KERN_INFO "Unpacking initramfs...\n");
703 
704 	err = unpack_to_rootfs((char *)initrd_start, initrd_end - initrd_start);
705 	if (err) {
706 #ifdef CONFIG_BLK_DEV_RAM
707 		populate_initrd_image(err);
708 #else
709 		printk(KERN_EMERG "Initramfs unpacking failed: %s\n", err);
710 #endif
711 	}
712 
713 done:
714 	/*
715 	 * If the initrd region is overlapped with crashkernel reserved region,
716 	 * free only memory that is not part of crashkernel region.
717 	 */
718 	if (!do_retain_initrd && initrd_start && !kexec_free_initrd())
719 		free_initrd_mem(initrd_start, initrd_end);
720 	initrd_start = 0;
721 	initrd_end = 0;
722 
723 	flush_delayed_fput();
724 	task_work_run();
725 }
726 
727 static ASYNC_DOMAIN_EXCLUSIVE(initramfs_domain);
728 static async_cookie_t initramfs_cookie;
729 
wait_for_initramfs(void)730 void wait_for_initramfs(void)
731 {
732 	if (!initramfs_cookie) {
733 		/*
734 		 * Something before rootfs_initcall wants to access
735 		 * the filesystem/initramfs. Probably a bug. Make a
736 		 * note, avoid deadlocking the machine, and let the
737 		 * caller's access fail as it used to.
738 		 */
739 		pr_warn_once("wait_for_initramfs() called before rootfs_initcalls\n");
740 		return;
741 	}
742 	async_synchronize_cookie_domain(initramfs_cookie + 1, &initramfs_domain);
743 }
744 EXPORT_SYMBOL_GPL(wait_for_initramfs);
745 
populate_rootfs(void)746 static int __init populate_rootfs(void)
747 {
748 	initramfs_cookie = async_schedule_domain(do_populate_rootfs, NULL,
749 						 &initramfs_domain);
750 	usermodehelper_enable();
751 	if (!initramfs_async)
752 		wait_for_initramfs();
753 	return 0;
754 }
755 rootfs_initcall(populate_rootfs);
756