xref: /openbmc/linux/fs/proc/kcore.c (revision 9a29f5fc) 
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 			struct kcore_list *iter;
483 
484 			m = NULL;
485 			list_for_each_entry(iter, &kclist_head, list) {
486 				if (start >= iter->addr &&
487 				    start < iter->addr + iter->size) {
488 					m = iter;
489 					break;
490 				}
491 			}
492 		}
493 
494 		if (page_offline_frozen++ % MAX_ORDER_NR_PAGES == 0) {
495 			page_offline_thaw();
496 			cond_resched();
497 			page_offline_freeze();
498 		}
499 
500 		if (!m) {
501 			if (clear_user(buffer, tsz)) {
502 				ret = -EFAULT;
503 				goto out;
504 			}
505 			goto skip;
506 		}
507 
508 		switch (m->type) {
509 		case KCORE_VMALLOC:
510 			vread(buf, (char *)start, tsz);
511 			/* we have to zero-fill user buffer even if no read */
512 			if (copy_to_user(buffer, buf, tsz)) {
513 				ret = -EFAULT;
514 				goto out;
515 			}
516 			break;
517 		case KCORE_USER:
518 			/* User page is handled prior to normal kernel page: */
519 			if (copy_to_user(buffer, (char *)start, tsz)) {
520 				ret = -EFAULT;
521 				goto out;
522 			}
523 			break;
524 		case KCORE_RAM:
525 			pfn = __pa(start) >> PAGE_SHIFT;
526 			page = pfn_to_online_page(pfn);
527 
528 			/*
529 			 * Don't read offline sections, logically offline pages
530 			 * (e.g., inflated in a balloon), hwpoisoned pages,
531 			 * and explicitly excluded physical ranges.
532 			 */
533 			if (!page || PageOffline(page) ||
534 			    is_page_hwpoison(page) || !pfn_is_ram(pfn)) {
535 				if (clear_user(buffer, tsz)) {
536 					ret = -EFAULT;
537 					goto out;
538 				}
539 				break;
540 			}
541 			fallthrough;
542 		case KCORE_VMEMMAP:
543 		case KCORE_TEXT:
544 			if (kern_addr_valid(start)) {
545 				/*
546 				 * Using bounce buffer to bypass the
547 				 * hardened user copy kernel text checks.
548 				 */
549 				if (copy_from_kernel_nofault(buf, (void *)start,
550 						tsz)) {
551 					if (clear_user(buffer, tsz)) {
552 						ret = -EFAULT;
553 						goto out;
554 					}
555 				} else {
556 					if (copy_to_user(buffer, buf, tsz)) {
557 						ret = -EFAULT;
558 						goto out;
559 					}
560 				}
561 			} else {
562 				if (clear_user(buffer, tsz)) {
563 					ret = -EFAULT;
564 					goto out;
565 				}
566 			}
567 			break;
568 		default:
569 			pr_warn_once("Unhandled KCORE type: %d\n", m->type);
570 			if (clear_user(buffer, tsz)) {
571 				ret = -EFAULT;
572 				goto out;
573 			}
574 		}
575 skip:
576 		buflen -= tsz;
577 		*fpos += tsz;
578 		buffer += tsz;
579 		start += tsz;
580 		tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
581 	}
582 
583 out:
584 	page_offline_thaw();
585 	up_read(&kclist_lock);
586 	if (ret)
587 		return ret;
588 	return orig_buflen - buflen;
589 }
590 
591 static int open_kcore(struct inode *inode, struct file *filp)
592 {
593 	int ret = security_locked_down(LOCKDOWN_KCORE);
594 
595 	if (!capable(CAP_SYS_RAWIO))
596 		return -EPERM;
597 
598 	if (ret)
599 		return ret;
600 
601 	filp->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
602 	if (!filp->private_data)
603 		return -ENOMEM;
604 
605 	if (kcore_need_update)
606 		kcore_update_ram();
607 	if (i_size_read(inode) != proc_root_kcore->size) {
608 		inode_lock(inode);
609 		i_size_write(inode, proc_root_kcore->size);
610 		inode_unlock(inode);
611 	}
612 	return 0;
613 }
614 
615 static int release_kcore(struct inode *inode, struct file *file)
616 {
617 	kfree(file->private_data);
618 	return 0;
619 }
620 
621 static const struct proc_ops kcore_proc_ops = {
622 	.proc_read	= read_kcore,
623 	.proc_open	= open_kcore,
624 	.proc_release	= release_kcore,
625 	.proc_lseek	= default_llseek,
626 };
627 
628 /* just remember that we have to update kcore */
629 static int __meminit kcore_callback(struct notifier_block *self,
630 				    unsigned long action, void *arg)
631 {
632 	switch (action) {
633 	case MEM_ONLINE:
634 	case MEM_OFFLINE:
635 		kcore_need_update = 1;
636 		break;
637 	}
638 	return NOTIFY_OK;
639 }
640 
641 static struct notifier_block kcore_callback_nb __meminitdata = {
642 	.notifier_call = kcore_callback,
643 	.priority = 0,
644 };
645 
646 static struct kcore_list kcore_vmalloc;
647 
648 #ifdef CONFIG_ARCH_PROC_KCORE_TEXT
649 static struct kcore_list kcore_text;
650 /*
651  * If defined, special segment is used for mapping kernel text instead of
652  * direct-map area. We need to create special TEXT section.
653  */
654 static void __init proc_kcore_text_init(void)
655 {
656 	kclist_add(&kcore_text, _text, _end - _text, KCORE_TEXT);
657 }
658 #else
659 static void __init proc_kcore_text_init(void)
660 {
661 }
662 #endif
663 
664 #if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
665 /*
666  * MODULES_VADDR has no intersection with VMALLOC_ADDR.
667  */
668 static struct kcore_list kcore_modules;
669 static void __init add_modules_range(void)
670 {
671 	if (MODULES_VADDR != VMALLOC_START && MODULES_END != VMALLOC_END) {
672 		kclist_add(&kcore_modules, (void *)MODULES_VADDR,
673 			MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
674 	}
675 }
676 #else
677 static void __init add_modules_range(void)
678 {
679 }
680 #endif
681 
682 static int __init proc_kcore_init(void)
683 {
684 	proc_root_kcore = proc_create("kcore", S_IRUSR, NULL, &kcore_proc_ops);
685 	if (!proc_root_kcore) {
686 		pr_err("couldn't create /proc/kcore\n");
687 		return 0; /* Always returns 0. */
688 	}
689 	/* Store text area if it's special */
690 	proc_kcore_text_init();
691 	/* Store vmalloc area */
692 	kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
693 		VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
694 	add_modules_range();
695 	/* Store direct-map area from physical memory map */
696 	kcore_update_ram();
697 	register_hotmemory_notifier(&kcore_callback_nb);
698 
699 	return 0;
700 }
701 fs_initcall(proc_kcore_init);
702