init/initramfs.c

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