fs/proc/kcore.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *      fs/proc/kcore.c kernel ELF core dumper
   4  *
   5  *      Modelled on fs/exec.c:aout_core_dump()
   6  *      Jeremy Fitzhardinge <jeremy@sw.oz.au>
   7  *      ELF version written by David Howells <David.Howells@nexor.co.uk>
   8  *      Modified and incorporated into 2.3.x by Tigran Aivazian <tigran@veritas.com>
   9  *      Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@veritas.com>
  10  *      Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com>
  11  */
  12
  13 #include <linux/crash_core.h>
  14 #include <linux/mm.h>
  15 #include <linux/proc_fs.h>
  16 #include <linux/kcore.h>
  17 #include <linux/user.h>
  18 #include <linux/capability.h>
  19 #include <linux/elf.h>
  20 #include <linux/elfcore.h>
  21 #include <linux/notifier.h>
  22 #include <linux/vmalloc.h>
  23 #include <linux/highmem.h>
  24 #include <linux/printk.h>
  25 #include <linux/memblock.h>
  26 #include <linux/init.h>
  27 #include <linux/slab.h>
  28 #include <linux/uaccess.h>
  29 #include <asm/io.h>
  30 #include <linux/list.h>
  31 #include <linux/ioport.h>
  32 #include <linux/memory.h>
  33 #include <linux/sched/task.h>
  34 #include <linux/security.h>
  35 #include <asm/sections.h>
  36 #include "internal.h"
  37
  38 #define CORE_STR "CORE"
  39
  40 #ifndef ELF_CORE_EFLAGS
  41 #define ELF_CORE_EFLAGS 0
  42 #endif
  43
  44 static struct proc_dir_entry *proc_root_kcore;
  45
  46
  47 #ifndef kc_vaddr_to_offset
  48 #define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
  49 #endif
  50 #ifndef kc_offset_to_vaddr
  51 #define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
  52 #endif
  53
  54 static LIST_HEAD(kclist_head);
  55 static DECLARE_RWSEM(kclist_lock);
  56 static int kcore_need_update = 1;
  57
  58 /*
  59  * Returns > 0 for RAM pages, 0 for non-RAM pages, < 0 on error
  60  * Same as oldmem_pfn_is_ram in vmcore
  61  */
  62 static int (*mem_pfn_is_ram)(unsigned long pfn);
  63
  64 int __init register_mem_pfn_is_ram(int (*fn)(unsigned long pfn))
  65 {
  66         if (mem_pfn_is_ram)
  67                 return -EBUSY;
  68         mem_pfn_is_ram = fn;
  69         return 0;
  70 }
  71
  72 static int pfn_is_ram(unsigned long pfn)
  73 {
  74         if (mem_pfn_is_ram)
  75                 return mem_pfn_is_ram(pfn);
  76         else
  77                 return 1;
  78 }
  79
  80 /* This doesn't grab kclist_lock, so it should only be used at init time. */
  81 void __init kclist_add(struct kcore_list *new, void *addr, size_t size,
  82                        int type)
  83 {
  84         new->addr = (unsigned long)addr;
  85         new->size = size;
  86         new->type = type;
  87
  88         list_add_tail(&new->list, &kclist_head);
  89 }
  90
  91 static size_t get_kcore_size(int *nphdr, size_t *phdrs_len, size_t *notes_len,
  92                              size_t *data_offset)
  93 {
  94         size_t try, size;
  95         struct kcore_list *m;
  96
  97         *nphdr = 1; /* PT_NOTE */
  98         size = 0;
  99
 100         list_for_each_entry(m, &kclist_head, list) {
 101                 try = kc_vaddr_to_offset((size_t)m->addr + m->size);
 102                 if (try > size)
 103                         size = try;
 104                 *nphdr = *nphdr + 1;
 105         }
 106
 107         *phdrs_len = *nphdr * sizeof(struct elf_phdr);
 108         *notes_len = (4 * sizeof(struct elf_note) +
 109                       3 * ALIGN(sizeof(CORE_STR), 4) +
 110                       VMCOREINFO_NOTE_NAME_BYTES +
 111                       ALIGN(sizeof(struct elf_prstatus), 4) +
 112                       ALIGN(sizeof(struct elf_prpsinfo), 4) +
 113                       ALIGN(arch_task_struct_size, 4) +
 114                       ALIGN(vmcoreinfo_size, 4));
 115         *data_offset = PAGE_ALIGN(sizeof(struct elfhdr) + *phdrs_len +
 116                                   *notes_len);
 117         return *data_offset + size;
 118 }
 119
 120 #ifdef CONFIG_HIGHMEM
 121 /*
 122  * If no highmem, we can assume [0...max_low_pfn) continuous range of memory
 123  * because memory hole is not as big as !HIGHMEM case.
 124  * (HIGHMEM is special because part of memory is _invisible_ from the kernel.)
 125  */
 126 static int kcore_ram_list(struct list_head *head)
 127 {
 128         struct kcore_list *ent;
 129
 130         ent = kmalloc(sizeof(*ent), GFP_KERNEL);
 131         if (!ent)
 132                 return -ENOMEM;
 133         ent->addr = (unsigned long)__va(0);
 134         ent->size = max_low_pfn << PAGE_SHIFT;
 135         ent->type = KCORE_RAM;
 136         list_add(&ent->list, head);
 137         return 0;
 138 }
 139
 140 #else /* !CONFIG_HIGHMEM */
 141
 142 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 143 /* calculate vmemmap's address from given system ram pfn and register it */
 144 static int
 145 get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
 146 {
 147         unsigned long pfn = __pa(ent->addr) >> PAGE_SHIFT;
 148         unsigned long nr_pages = ent->size >> PAGE_SHIFT;
 149         unsigned long start, end;
 150         struct kcore_list *vmm, *tmp;
 151
 152
 153         start = ((unsigned long)pfn_to_page(pfn)) & PAGE_MASK;
 154         end = ((unsigned long)pfn_to_page(pfn + nr_pages)) - 1;
 155         end = PAGE_ALIGN(end);
 156         /* overlap check (because we have to align page */
 157         list_for_each_entry(tmp, head, list) {
 158                 if (tmp->type != KCORE_VMEMMAP)
 159                         continue;
 160                 if (start < tmp->addr + tmp->size)
 161                         if (end > tmp->addr)
 162                                 end = tmp->addr;
 163         }
 164         if (start < end) {
 165                 vmm = kmalloc(sizeof(*vmm), GFP_KERNEL);
 166                 if (!vmm)
 167                         return 0;
 168                 vmm->addr = start;
 169                 vmm->size = end - start;
 170                 vmm->type = KCORE_VMEMMAP;
 171                 list_add_tail(&vmm->list, head);
 172         }
 173         return 1;
 174
 175 }
 176 #else
 177 static int
 178 get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
 179 {
 180         return 1;
 181 }
 182
 183 #endif
 184
 185 static int
 186 kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg)
 187 {
 188         struct list_head *head = (struct list_head *)arg;
 189         struct kcore_list *ent;
 190         struct page *p;
 191
 192         if (!pfn_valid(pfn))
 193                 return 1;
 194
 195         p = pfn_to_page(pfn);
 196
 197         ent = kmalloc(sizeof(*ent), GFP_KERNEL);
 198         if (!ent)
 199                 return -ENOMEM;
 200         ent->addr = (unsigned long)page_to_virt(p);
 201         ent->size = nr_pages << PAGE_SHIFT;
 202
 203         if (!virt_addr_valid(ent->addr))
 204                 goto free_out;
 205
 206         /* cut not-mapped area. ....from ppc-32 code. */
 207         if (ULONG_MAX - ent->addr < ent->size)
 208                 ent->size = ULONG_MAX - ent->addr;
 209
 210         /*
 211          * We've already checked virt_addr_valid so we know this address
 212          * is a valid pointer, therefore we can check against it to determine
 213          * if we need to trim
 214          */
 215         if (VMALLOC_START > ent->addr) {
 216                 if (VMALLOC_START - ent->addr < ent->size)
 217                         ent->size = VMALLOC_START - ent->addr;
 218         }
 219
 220         ent->type = KCORE_RAM;
 221         list_add_tail(&ent->list, head);
 222
 223         if (!get_sparsemem_vmemmap_info(ent, head)) {
 224                 list_del(&ent->list);
 225                 goto free_out;
 226         }
 227
 228         return 0;
 229 free_out:
 230         kfree(ent);
 231         return 1;
 232 }
 233
 234 static int kcore_ram_list(struct list_head *list)
 235 {
 236         int nid, ret;
 237         unsigned long end_pfn;
 238
 239         /* Not inialized....update now */
 240         /* find out "max pfn" */
 241         end_pfn = 0;
 242         for_each_node_state(nid, N_MEMORY) {
 243                 unsigned long node_end;
 244                 node_end = node_end_pfn(nid);
 245                 if (end_pfn < node_end)
 246                         end_pfn = node_end;
 247         }
 248         /* scan 0 to max_pfn */
 249         ret = walk_system_ram_range(0, end_pfn, list, kclist_add_private);
 250         if (ret)
 251                 return -ENOMEM;
 252         return 0;
 253 }
 254 #endif /* CONFIG_HIGHMEM */
 255
 256 static int kcore_update_ram(void)
 257 {
 258         LIST_HEAD(list);
 259         LIST_HEAD(garbage);
 260         int nphdr;
 261         size_t phdrs_len, notes_len, data_offset;
 262         struct kcore_list *tmp, *pos;
 263         int ret = 0;
 264
 265         down_write(&kclist_lock);
 266         if (!xchg(&kcore_need_update, 0))
 267                 goto out;
 268
 269         ret = kcore_ram_list(&list);
 270         if (ret) {
 271                 /* Couldn't get the RAM list, try again next time. */
 272                 WRITE_ONCE(kcore_need_update, 1);
 273                 list_splice_tail(&list, &garbage);
 274                 goto out;
 275         }
 276
 277         list_for_each_entry_safe(pos, tmp, &kclist_head, list) {
 278                 if (pos->type == KCORE_RAM || pos->type == KCORE_VMEMMAP)
 279                         list_move(&pos->list, &garbage);
 280         }
 281         list_splice_tail(&list, &kclist_head);
 282
 283         proc_root_kcore->size = get_kcore_size(&nphdr, &phdrs_len, &notes_len,
 284                                                &data_offset);
 285
 286 out:
 287         up_write(&kclist_lock);
 288         list_for_each_entry_safe(pos, tmp, &garbage, list) {
 289                 list_del(&pos->list);
 290                 kfree(pos);
 291         }
 292         return ret;
 293 }
 294
 295 static void append_kcore_note(char *notes, size_t *i, const char *name,
 296                               unsigned int type, const void *desc,
 297                               size_t descsz)
 298 {
 299         struct elf_note *note = (struct elf_note *)&notes[*i];
 300
 301         note->n_namesz = strlen(name) + 1;
 302         note->n_descsz = descsz;
 303         note->n_type = type;
 304         *i += sizeof(*note);
 305         memcpy(&notes[*i], name, note->n_namesz);
 306         *i = ALIGN(*i + note->n_namesz, 4);
 307         memcpy(&notes[*i], desc, descsz);
 308         *i = ALIGN(*i + descsz, 4);
 309 }
 310
 311 static ssize_t
 312 read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 313 {
 314         char *buf = file->private_data;
 315         size_t phdrs_offset, notes_offset, data_offset;
 316         size_t page_offline_frozen = 1;
 317         size_t phdrs_len, notes_len;
 318         struct kcore_list *m;
 319         size_t tsz;
 320         int nphdr;
 321         unsigned long start;
 322         size_t orig_buflen = buflen;
 323         int ret = 0;
 324
 325         down_read(&kclist_lock);
 326         /*
 327          * Don't race against drivers that set PageOffline() and expect no
 328          * further page access.
 329          */
 330         page_offline_freeze();
 331
 332         get_kcore_size(&nphdr, &phdrs_len, &notes_len, &data_offset);
 333         phdrs_offset = sizeof(struct elfhdr);
 334         notes_offset = phdrs_offset + phdrs_len;
 335
 336         /* ELF file header. */
 337         if (buflen && *fpos < sizeof(struct elfhdr)) {
 338                 struct elfhdr ehdr = {
 339                         .e_ident = {
 340                                 [EI_MAG0] = ELFMAG0,
 341                                 [EI_MAG1] = ELFMAG1,
 342                                 [EI_MAG2] = ELFMAG2,
 343                                 [EI_MAG3] = ELFMAG3,
 344                                 [EI_CLASS] = ELF_CLASS,
 345                                 [EI_DATA] = ELF_DATA,
 346                                 [EI_VERSION] = EV_CURRENT,
 347                                 [EI_OSABI] = ELF_OSABI,
 348                         },
 349                         .e_type = ET_CORE,
 350                         .e_machine = ELF_ARCH,
 351                         .e_version = EV_CURRENT,
 352                         .e_phoff = sizeof(struct elfhdr),
 353                         .e_flags = ELF_CORE_EFLAGS,
 354                         .e_ehsize = sizeof(struct elfhdr),
 355                         .e_phentsize = sizeof(struct elf_phdr),
 356                         .e_phnum = nphdr,
 357                 };
 358
 359                 tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *fpos);
 360                 if (copy_to_user(buffer, (char *)&ehdr + *fpos, tsz)) {
 361                         ret = -EFAULT;
 362                         goto out;
 363                 }
 364
 365                 buffer += tsz;
 366                 buflen -= tsz;
 367                 *fpos += tsz;
 368         }
 369
 370         /* ELF program headers. */
 371         if (buflen && *fpos < phdrs_offset + phdrs_len) {
 372                 struct elf_phdr *phdrs, *phdr;
 373
 374                 phdrs = kzalloc(phdrs_len, GFP_KERNEL);
 375                 if (!phdrs) {
 376                         ret = -ENOMEM;
 377                         goto out;
 378                 }
 379
 380                 phdrs[0].p_type = PT_NOTE;
 381                 phdrs[0].p_offset = notes_offset;
 382                 phdrs[0].p_filesz = notes_len;
 383
 384                 phdr = &phdrs[1];
 385                 list_for_each_entry(m, &kclist_head, list) {
 386                         phdr->p_type = PT_LOAD;
 387                         phdr->p_flags = PF_R | PF_W | PF_X;
 388                         phdr->p_offset = kc_vaddr_to_offset(m->addr) + data_offset;
 389                         phdr->p_vaddr = (size_t)m->addr;
 390                         if (m->type == KCORE_RAM)
 391                                 phdr->p_paddr = __pa(m->addr);
 392                         else if (m->type == KCORE_TEXT)
 393                                 phdr->p_paddr = __pa_symbol(m->addr);
 394                         else
 395                                 phdr->p_paddr = (elf_addr_t)-1;
 396                         phdr->p_filesz = phdr->p_memsz = m->size;
 397                         phdr->p_align = PAGE_SIZE;
 398                         phdr++;
 399                 }
 400
 401                 tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *fpos);
 402                 if (copy_to_user(buffer, (char *)phdrs + *fpos - phdrs_offset,
 403                                  tsz)) {
 404                         kfree(phdrs);
 405                         ret = -EFAULT;
 406                         goto out;
 407                 }
 408                 kfree(phdrs);
 409
 410                 buffer += tsz;
 411                 buflen -= tsz;
 412                 *fpos += tsz;
 413         }
 414
 415         /* ELF note segment. */
 416         if (buflen && *fpos < notes_offset + notes_len) {
 417                 struct elf_prstatus prstatus = {};
 418                 struct elf_prpsinfo prpsinfo = {
 419                         .pr_sname = 'R',
 420                         .pr_fname = "vmlinux",
 421                 };
 422                 char *notes;
 423                 size_t i = 0;
 424
 425                 strlcpy(prpsinfo.pr_psargs, saved_command_line,
 426                         sizeof(prpsinfo.pr_psargs));
 427
 428                 notes = kzalloc(notes_len, GFP_KERNEL);
 429                 if (!notes) {
 430                         ret = -ENOMEM;
 431                         goto out;
 432                 }
 433
 434                 append_kcore_note(notes, &i, CORE_STR, NT_PRSTATUS, &prstatus,
 435                                   sizeof(prstatus));
 436                 append_kcore_note(notes, &i, CORE_STR, NT_PRPSINFO, &prpsinfo,
 437                                   sizeof(prpsinfo));
 438                 append_kcore_note(notes, &i, CORE_STR, NT_TASKSTRUCT, current,
 439                                   arch_task_struct_size);
 440                 /*
 441                  * vmcoreinfo_size is mostly constant after init time, but it
 442                  * can be changed by crash_save_vmcoreinfo(). Racing here with a
 443                  * panic on another CPU before the machine goes down is insanely
 444                  * unlikely, but it's better to not leave potential buffer
 445                  * overflows lying around, regardless.
 446                  */
 447                 append_kcore_note(notes, &i, VMCOREINFO_NOTE_NAME, 0,
 448                                   vmcoreinfo_data,
 449                                   min(vmcoreinfo_size, notes_len - i));
 450
 451                 tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos);
 452                 if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) {
 453                         kfree(notes);
 454                         ret = -EFAULT;
 455                         goto out;
 456                 }
 457                 kfree(notes);
 458
 459                 buffer += tsz;
 460                 buflen -= tsz;
 461                 *fpos += tsz;
 462         }
 463
 464         /*
 465          * Check to see if our file offset matches with any of
 466          * the addresses in the elf_phdr on our list.
 467          */
 468         start = kc_offset_to_vaddr(*fpos - data_offset);
 469         if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
 470                 tsz = buflen;
 471
 472         m = NULL;
 473         while (buflen) {
 474                 struct page *page;
 475                 unsigned long pfn;
 476
 477                 /*
 478                  * If this is the first iteration or the address is not within
 479                  * the previous entry, search for a matching entry.
 480                  */
 481                 if (!m || start < m->addr || start >= m->addr + m->size) {
 482                         list_for_each_entry(m, &kclist_head, list) {
 483                                 if (start >= m->addr &&
 484                                     start < m->addr + m->size)
 485                                         break;
 486                         }
 487                 }
 488
 489                 if (page_offline_frozen++ % MAX_ORDER_NR_PAGES == 0) {
 490                         page_offline_thaw();
 491                         cond_resched();
 492                         page_offline_freeze();
 493                 }
 494
 495                 if (&m->list == &kclist_head) {
 496                         if (clear_user(buffer, tsz)) {
 497                                 ret = -EFAULT;
 498                                 goto out;
 499                         }
 500                         m = NULL;       /* skip the list anchor */
 501                         goto skip;
 502                 }
 503
 504                 switch (m->type) {
 505                 case KCORE_VMALLOC:
 506                         vread(buf, (char *)start, tsz);
 507                         /* we have to zero-fill user buffer even if no read */
 508                         if (copy_to_user(buffer, buf, tsz)) {
 509                                 ret = -EFAULT;
 510                                 goto out;
 511                         }
 512                         break;
 513                 case KCORE_USER:
 514                         /* User page is handled prior to normal kernel page: */
 515                         if (copy_to_user(buffer, (char *)start, tsz)) {
 516                                 ret = -EFAULT;
 517                                 goto out;
 518                         }
 519                         break;
 520                 case KCORE_RAM:
 521                         pfn = __pa(start) >> PAGE_SHIFT;
 522                         page = pfn_to_online_page(pfn);
 523
 524                         /*
 525                          * Don't read offline sections, logically offline pages
 526                          * (e.g., inflated in a balloon), hwpoisoned pages,
 527                          * and explicitly excluded physical ranges.
 528                          */
 529                         if (!page || PageOffline(page) ||
 530                             is_page_hwpoison(page) || !pfn_is_ram(pfn)) {
 531                                 if (clear_user(buffer, tsz)) {
 532                                         ret = -EFAULT;
 533                                         goto out;
 534                                 }
 535                                 break;
 536                         }
 537                         fallthrough;
 538                 case KCORE_VMEMMAP:
 539                 case KCORE_TEXT:
 540                         if (kern_addr_valid(start)) {
 541                                 /*
 542                                  * Using bounce buffer to bypass the
 543                                  * hardened user copy kernel text checks.
 544                                  */
 545                                 if (copy_from_kernel_nofault(buf, (void *)start,
 546                                                 tsz)) {
 547                                         if (clear_user(buffer, tsz)) {
 548                                                 ret = -EFAULT;
 549                                                 goto out;
 550                                         }
 551                                 } else {
 552                                         if (copy_to_user(buffer, buf, tsz)) {
 553                                                 ret = -EFAULT;
 554                                                 goto out;
 555                                         }
 556                                 }
 557                         } else {
 558                                 if (clear_user(buffer, tsz)) {
 559                                         ret = -EFAULT;
 560                                         goto out;
 561                                 }
 562                         }
 563                         break;
 564                 default:
 565                         pr_warn_once("Unhandled KCORE type: %d\n", m->type);
 566                         if (clear_user(buffer, tsz)) {
 567                                 ret = -EFAULT;
 568                                 goto out;
 569                         }
 570                 }
 571 skip:
 572                 buflen -= tsz;
 573                 *fpos += tsz;
 574                 buffer += tsz;
 575                 start += tsz;
 576                 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
 577         }
 578
 579 out:
 580         page_offline_thaw();
 581         up_read(&kclist_lock);
 582         if (ret)
 583                 return ret;
 584         return orig_buflen - buflen;
 585 }
 586
 587 static int open_kcore(struct inode *inode, struct file *filp)
 588 {
 589         int ret = security_locked_down(LOCKDOWN_KCORE);
 590
 591         if (!capable(CAP_SYS_RAWIO))
 592                 return -EPERM;
 593
 594         if (ret)
 595                 return ret;
 596
 597         filp->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
 598         if (!filp->private_data)
 599                 return -ENOMEM;
 600
 601         if (kcore_need_update)
 602                 kcore_update_ram();
 603         if (i_size_read(inode) != proc_root_kcore->size) {
 604                 inode_lock(inode);
 605                 i_size_write(inode, proc_root_kcore->size);
 606                 inode_unlock(inode);
 607         }
 608         return 0;
 609 }
 610
 611 static int release_kcore(struct inode *inode, struct file *file)
 612 {
 613         kfree(file->private_data);
 614         return 0;
 615 }
 616
 617 static const struct proc_ops kcore_proc_ops = {
 618         .proc_read      = read_kcore,
 619         .proc_open      = open_kcore,
 620         .proc_release   = release_kcore,
 621         .proc_lseek     = default_llseek,
 622 };
 623
 624 /* just remember that we have to update kcore */
 625 static int __meminit kcore_callback(struct notifier_block *self,
 626                                     unsigned long action, void *arg)
 627 {
 628         switch (action) {
 629         case MEM_ONLINE:
 630         case MEM_OFFLINE:
 631                 kcore_need_update = 1;
 632                 break;
 633         }
 634         return NOTIFY_OK;
 635 }
 636
 637 static struct notifier_block kcore_callback_nb __meminitdata = {
 638         .notifier_call = kcore_callback,
 639         .priority = 0,
 640 };
 641
 642 static struct kcore_list kcore_vmalloc;
 643
 644 #ifdef CONFIG_ARCH_PROC_KCORE_TEXT
 645 static struct kcore_list kcore_text;
 646 /*
 647  * If defined, special segment is used for mapping kernel text instead of
 648  * direct-map area. We need to create special TEXT section.
 649  */
 650 static void __init proc_kcore_text_init(void)
 651 {
 652         kclist_add(&kcore_text, _text, _end - _text, KCORE_TEXT);
 653 }
 654 #else
 655 static void __init proc_kcore_text_init(void)
 656 {
 657 }
 658 #endif
 659
 660 #if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
 661 /*
 662  * MODULES_VADDR has no intersection with VMALLOC_ADDR.
 663  */
 664 static struct kcore_list kcore_modules;
 665 static void __init add_modules_range(void)
 666 {
 667         if (MODULES_VADDR != VMALLOC_START && MODULES_END != VMALLOC_END) {
 668                 kclist_add(&kcore_modules, (void *)MODULES_VADDR,
 669                         MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
 670         }
 671 }
 672 #else
 673 static void __init add_modules_range(void)
 674 {
 675 }
 676 #endif
 677
 678 static int __init proc_kcore_init(void)
 679 {
 680         proc_root_kcore = proc_create("kcore", S_IRUSR, NULL, &kcore_proc_ops);
 681         if (!proc_root_kcore) {
 682                 pr_err("couldn't create /proc/kcore\n");
 683                 return 0; /* Always returns 0. */
 684         }
 685         /* Store text area if it's special */
 686         proc_kcore_text_init();
 687         /* Store vmalloc area */
 688         kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 689                 VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
 690         add_modules_range();
 691         /* Store direct-map area from physical memory map */
 692         kcore_update_ram();
 693         register_hotmemory_notifier(&kcore_callback_nb);
 694
 695         return 0;
 696 }
 697 fs_initcall(proc_kcore_init);