xref: /linux/fs/proc/kcore.c (revision 06a130e42a5bfc84795464bff023bff4c16f58c5)
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/vmcore_info.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/vmalloc.h>
22 #include <linux/highmem.h>
23 #include <linux/printk.h>
24 #include <linux/memblock.h>
25 #include <linux/init.h>
26 #include <linux/slab.h>
27 #include <linux/uio.h>
28 #include <asm/io.h>
29 #include <linux/list.h>
30 #include <linux/ioport.h>
31 #include <linux/memory.h>
32 #include <linux/sched/task.h>
33 #include <linux/security.h>
34 #include <asm/sections.h>
35 #include "internal.h"
36 
37 #define CORE_STR "CORE"
38 
39 #ifndef ELF_CORE_EFLAGS
40 #define ELF_CORE_EFLAGS	0
41 #endif
42 
43 static struct proc_dir_entry *proc_root_kcore;
44 
45 
46 #ifndef kc_vaddr_to_offset
47 #define	kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
48 #endif
49 #ifndef	kc_offset_to_vaddr
50 #define	kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
51 #endif
52 
53 #ifndef kc_xlate_dev_mem_ptr
54 #define kc_xlate_dev_mem_ptr kc_xlate_dev_mem_ptr
55 static inline void *kc_xlate_dev_mem_ptr(phys_addr_t phys)
56 {
57 	return __va(phys);
58 }
59 #endif
60 #ifndef kc_unxlate_dev_mem_ptr
61 #define kc_unxlate_dev_mem_ptr kc_unxlate_dev_mem_ptr
62 static inline void kc_unxlate_dev_mem_ptr(phys_addr_t phys, void *virt)
63 {
64 }
65 #endif
66 
67 static LIST_HEAD(kclist_head);
68 static DECLARE_RWSEM(kclist_lock);
69 static int kcore_need_update = 1;
70 
71 /*
72  * Returns > 0 for RAM pages, 0 for non-RAM pages, < 0 on error
73  * Same as oldmem_pfn_is_ram in vmcore
74  */
75 static int (*mem_pfn_is_ram)(unsigned long pfn);
76 
77 int __init register_mem_pfn_is_ram(int (*fn)(unsigned long pfn))
78 {
79 	if (mem_pfn_is_ram)
80 		return -EBUSY;
81 	mem_pfn_is_ram = fn;
82 	return 0;
83 }
84 
85 static int pfn_is_ram(unsigned long pfn)
86 {
87 	if (mem_pfn_is_ram)
88 		return mem_pfn_is_ram(pfn);
89 	else
90 		return 1;
91 }
92 
93 /* This doesn't grab kclist_lock, so it should only be used at init time. */
94 void __init kclist_add(struct kcore_list *new, void *addr, size_t size,
95 		       int type)
96 {
97 	new->addr = (unsigned long)addr;
98 	new->size = size;
99 	new->type = type;
100 
101 	list_add_tail(&new->list, &kclist_head);
102 }
103 
104 static size_t get_kcore_size(int *nphdr, size_t *phdrs_len, size_t *notes_len,
105 			     size_t *data_offset)
106 {
107 	size_t try, size;
108 	struct kcore_list *m;
109 
110 	*nphdr = 1; /* PT_NOTE */
111 	size = 0;
112 
113 	list_for_each_entry(m, &kclist_head, list) {
114 		try = kc_vaddr_to_offset((size_t)m->addr + m->size);
115 		if (try > size)
116 			size = try;
117 		*nphdr = *nphdr + 1;
118 	}
119 
120 	*phdrs_len = *nphdr * sizeof(struct elf_phdr);
121 	*notes_len = (4 * sizeof(struct elf_note) +
122 		      3 * ALIGN(sizeof(CORE_STR), 4) +
123 		      VMCOREINFO_NOTE_NAME_BYTES +
124 		      ALIGN(sizeof(struct elf_prstatus), 4) +
125 		      ALIGN(sizeof(struct elf_prpsinfo), 4) +
126 		      ALIGN(arch_task_struct_size, 4) +
127 		      ALIGN(vmcoreinfo_size, 4));
128 	*data_offset = PAGE_ALIGN(sizeof(struct elfhdr) + *phdrs_len +
129 				  *notes_len);
130 	return *data_offset + size;
131 }
132 
133 #ifdef CONFIG_HIGHMEM
134 /*
135  * If no highmem, we can assume [0...max_low_pfn) continuous range of memory
136  * because memory hole is not as big as !HIGHMEM case.
137  * (HIGHMEM is special because part of memory is _invisible_ from the kernel.)
138  */
139 static int kcore_ram_list(struct list_head *head)
140 {
141 	struct kcore_list *ent;
142 
143 	ent = kmalloc(sizeof(*ent), GFP_KERNEL);
144 	if (!ent)
145 		return -ENOMEM;
146 	ent->addr = (unsigned long)__va(0);
147 	ent->size = max_low_pfn << PAGE_SHIFT;
148 	ent->type = KCORE_RAM;
149 	list_add(&ent->list, head);
150 	return 0;
151 }
152 
153 #else /* !CONFIG_HIGHMEM */
154 
155 #ifdef CONFIG_SPARSEMEM_VMEMMAP
156 /* calculate vmemmap's address from given system ram pfn and register it */
157 static int
158 get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
159 {
160 	unsigned long pfn = __pa(ent->addr) >> PAGE_SHIFT;
161 	unsigned long nr_pages = ent->size >> PAGE_SHIFT;
162 	unsigned long start, end;
163 	struct kcore_list *vmm, *tmp;
164 
165 
166 	start = ((unsigned long)pfn_to_page(pfn)) & PAGE_MASK;
167 	end = ((unsigned long)pfn_to_page(pfn + nr_pages)) - 1;
168 	end = PAGE_ALIGN(end);
169 	/* overlap check (because we have to align page */
170 	list_for_each_entry(tmp, head, list) {
171 		if (tmp->type != KCORE_VMEMMAP)
172 			continue;
173 		if (start < tmp->addr + tmp->size)
174 			if (end > tmp->addr)
175 				end = tmp->addr;
176 	}
177 	if (start < end) {
178 		vmm = kmalloc(sizeof(*vmm), GFP_KERNEL);
179 		if (!vmm)
180 			return 0;
181 		vmm->addr = start;
182 		vmm->size = end - start;
183 		vmm->type = KCORE_VMEMMAP;
184 		list_add_tail(&vmm->list, head);
185 	}
186 	return 1;
187 
188 }
189 #else
190 static int
191 get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
192 {
193 	return 1;
194 }
195 
196 #endif
197 
198 static int
199 kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg)
200 {
201 	struct list_head *head = (struct list_head *)arg;
202 	struct kcore_list *ent;
203 	struct page *p;
204 
205 	if (!pfn_valid(pfn))
206 		return 1;
207 
208 	p = pfn_to_page(pfn);
209 
210 	ent = kmalloc(sizeof(*ent), GFP_KERNEL);
211 	if (!ent)
212 		return -ENOMEM;
213 	ent->addr = (unsigned long)page_to_virt(p);
214 	ent->size = nr_pages << PAGE_SHIFT;
215 
216 	if (!virt_addr_valid((void *)ent->addr))
217 		goto free_out;
218 
219 	/* cut not-mapped area. ....from ppc-32 code. */
220 	if (ULONG_MAX - ent->addr < ent->size)
221 		ent->size = ULONG_MAX - ent->addr;
222 
223 	/*
224 	 * We've already checked virt_addr_valid so we know this address
225 	 * is a valid pointer, therefore we can check against it to determine
226 	 * if we need to trim
227 	 */
228 	if (VMALLOC_START > ent->addr) {
229 		if (VMALLOC_START - ent->addr < ent->size)
230 			ent->size = VMALLOC_START - ent->addr;
231 	}
232 
233 	ent->type = KCORE_RAM;
234 	list_add_tail(&ent->list, head);
235 
236 	if (!get_sparsemem_vmemmap_info(ent, head)) {
237 		list_del(&ent->list);
238 		goto free_out;
239 	}
240 
241 	return 0;
242 free_out:
243 	kfree(ent);
244 	return 1;
245 }
246 
247 static int kcore_ram_list(struct list_head *list)
248 {
249 	int nid, ret;
250 	unsigned long end_pfn;
251 
252 	/* Not initialized....update now */
253 	/* find out "max pfn" */
254 	end_pfn = 0;
255 	for_each_node_state(nid, N_MEMORY) {
256 		unsigned long node_end;
257 		node_end = node_end_pfn(nid);
258 		if (end_pfn < node_end)
259 			end_pfn = node_end;
260 	}
261 	/* scan 0 to max_pfn */
262 	ret = walk_system_ram_range(0, end_pfn, list, kclist_add_private);
263 	if (ret)
264 		return -ENOMEM;
265 	return 0;
266 }
267 #endif /* CONFIG_HIGHMEM */
268 
269 static int kcore_update_ram(void)
270 {
271 	LIST_HEAD(list);
272 	LIST_HEAD(garbage);
273 	int nphdr;
274 	size_t phdrs_len, notes_len, data_offset;
275 	struct kcore_list *tmp, *pos;
276 	int ret = 0;
277 
278 	down_write(&kclist_lock);
279 	if (!xchg(&kcore_need_update, 0))
280 		goto out;
281 
282 	ret = kcore_ram_list(&list);
283 	if (ret) {
284 		/* Couldn't get the RAM list, try again next time. */
285 		WRITE_ONCE(kcore_need_update, 1);
286 		list_splice_tail(&list, &garbage);
287 		goto out;
288 	}
289 
290 	list_for_each_entry_safe(pos, tmp, &kclist_head, list) {
291 		if (pos->type == KCORE_RAM || pos->type == KCORE_VMEMMAP)
292 			list_move(&pos->list, &garbage);
293 	}
294 	list_splice_tail(&list, &kclist_head);
295 
296 	proc_root_kcore->size = get_kcore_size(&nphdr, &phdrs_len, &notes_len,
297 					       &data_offset);
298 
299 out:
300 	up_write(&kclist_lock);
301 	list_for_each_entry_safe(pos, tmp, &garbage, list) {
302 		list_del(&pos->list);
303 		kfree(pos);
304 	}
305 	return ret;
306 }
307 
308 static void append_kcore_note(char *notes, size_t *i, const char *name,
309 			      unsigned int type, const void *desc,
310 			      size_t descsz)
311 {
312 	struct elf_note *note = (struct elf_note *)&notes[*i];
313 
314 	note->n_namesz = strlen(name) + 1;
315 	note->n_descsz = descsz;
316 	note->n_type = type;
317 	*i += sizeof(*note);
318 	memcpy(&notes[*i], name, note->n_namesz);
319 	*i = ALIGN(*i + note->n_namesz, 4);
320 	memcpy(&notes[*i], desc, descsz);
321 	*i = ALIGN(*i + descsz, 4);
322 }
323 
324 static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter)
325 {
326 	struct file *file = iocb->ki_filp;
327 	char *buf = file->private_data;
328 	loff_t *fpos = &iocb->ki_pos;
329 	size_t phdrs_offset, notes_offset, data_offset;
330 	size_t page_offline_frozen = 1;
331 	size_t phdrs_len, notes_len;
332 	struct kcore_list *m;
333 	size_t tsz;
334 	int nphdr;
335 	unsigned long start;
336 	size_t buflen = iov_iter_count(iter);
337 	size_t orig_buflen = buflen;
338 	int ret = 0;
339 
340 	down_read(&kclist_lock);
341 	/*
342 	 * Don't race against drivers that set PageOffline() and expect no
343 	 * further page access.
344 	 */
345 	page_offline_freeze();
346 
347 	get_kcore_size(&nphdr, &phdrs_len, &notes_len, &data_offset);
348 	phdrs_offset = sizeof(struct elfhdr);
349 	notes_offset = phdrs_offset + phdrs_len;
350 
351 	/* ELF file header. */
352 	if (buflen && *fpos < sizeof(struct elfhdr)) {
353 		struct elfhdr ehdr = {
354 			.e_ident = {
355 				[EI_MAG0] = ELFMAG0,
356 				[EI_MAG1] = ELFMAG1,
357 				[EI_MAG2] = ELFMAG2,
358 				[EI_MAG3] = ELFMAG3,
359 				[EI_CLASS] = ELF_CLASS,
360 				[EI_DATA] = ELF_DATA,
361 				[EI_VERSION] = EV_CURRENT,
362 				[EI_OSABI] = ELF_OSABI,
363 			},
364 			.e_type = ET_CORE,
365 			.e_machine = ELF_ARCH,
366 			.e_version = EV_CURRENT,
367 			.e_phoff = sizeof(struct elfhdr),
368 			.e_flags = ELF_CORE_EFLAGS,
369 			.e_ehsize = sizeof(struct elfhdr),
370 			.e_phentsize = sizeof(struct elf_phdr),
371 			.e_phnum = nphdr,
372 		};
373 
374 		tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *fpos);
375 		if (copy_to_iter((char *)&ehdr + *fpos, tsz, iter) != tsz) {
376 			ret = -EFAULT;
377 			goto out;
378 		}
379 
380 		buflen -= tsz;
381 		*fpos += tsz;
382 	}
383 
384 	/* ELF program headers. */
385 	if (buflen && *fpos < phdrs_offset + phdrs_len) {
386 		struct elf_phdr *phdrs, *phdr;
387 
388 		phdrs = kzalloc(phdrs_len, GFP_KERNEL);
389 		if (!phdrs) {
390 			ret = -ENOMEM;
391 			goto out;
392 		}
393 
394 		phdrs[0].p_type = PT_NOTE;
395 		phdrs[0].p_offset = notes_offset;
396 		phdrs[0].p_filesz = notes_len;
397 
398 		phdr = &phdrs[1];
399 		list_for_each_entry(m, &kclist_head, list) {
400 			phdr->p_type = PT_LOAD;
401 			phdr->p_flags = PF_R | PF_W | PF_X;
402 			phdr->p_offset = kc_vaddr_to_offset(m->addr) + data_offset;
403 			phdr->p_vaddr = (size_t)m->addr;
404 			if (m->type == KCORE_RAM)
405 				phdr->p_paddr = __pa(m->addr);
406 			else if (m->type == KCORE_TEXT)
407 				phdr->p_paddr = __pa_symbol(m->addr);
408 			else
409 				phdr->p_paddr = (elf_addr_t)-1;
410 			phdr->p_filesz = phdr->p_memsz = m->size;
411 			phdr->p_align = PAGE_SIZE;
412 			phdr++;
413 		}
414 
415 		tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *fpos);
416 		if (copy_to_iter((char *)phdrs + *fpos - phdrs_offset, tsz,
417 				 iter) != tsz) {
418 			kfree(phdrs);
419 			ret = -EFAULT;
420 			goto out;
421 		}
422 		kfree(phdrs);
423 
424 		buflen -= tsz;
425 		*fpos += tsz;
426 	}
427 
428 	/* ELF note segment. */
429 	if (buflen && *fpos < notes_offset + notes_len) {
430 		struct elf_prstatus prstatus = {};
431 		struct elf_prpsinfo prpsinfo = {
432 			.pr_sname = 'R',
433 			.pr_fname = "vmlinux",
434 		};
435 		char *notes;
436 		size_t i = 0;
437 
438 		strscpy(prpsinfo.pr_psargs, saved_command_line,
439 			sizeof(prpsinfo.pr_psargs));
440 
441 		notes = kzalloc(notes_len, GFP_KERNEL);
442 		if (!notes) {
443 			ret = -ENOMEM;
444 			goto out;
445 		}
446 
447 		append_kcore_note(notes, &i, CORE_STR, NT_PRSTATUS, &prstatus,
448 				  sizeof(prstatus));
449 		append_kcore_note(notes, &i, CORE_STR, NT_PRPSINFO, &prpsinfo,
450 				  sizeof(prpsinfo));
451 		append_kcore_note(notes, &i, CORE_STR, NT_TASKSTRUCT, current,
452 				  arch_task_struct_size);
453 		/*
454 		 * vmcoreinfo_size is mostly constant after init time, but it
455 		 * can be changed by crash_save_vmcoreinfo(). Racing here with a
456 		 * panic on another CPU before the machine goes down is insanely
457 		 * unlikely, but it's better to not leave potential buffer
458 		 * overflows lying around, regardless.
459 		 */
460 		append_kcore_note(notes, &i, VMCOREINFO_NOTE_NAME, 0,
461 				  vmcoreinfo_data,
462 				  min(vmcoreinfo_size, notes_len - i));
463 
464 		tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos);
465 		if (copy_to_iter(notes + *fpos - notes_offset, tsz, iter) != tsz) {
466 			kfree(notes);
467 			ret = -EFAULT;
468 			goto out;
469 		}
470 		kfree(notes);
471 
472 		buflen -= tsz;
473 		*fpos += tsz;
474 	}
475 
476 	/*
477 	 * Check to see if our file offset matches with any of
478 	 * the addresses in the elf_phdr on our list.
479 	 */
480 	start = kc_offset_to_vaddr(*fpos - data_offset);
481 	if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
482 		tsz = buflen;
483 
484 	m = NULL;
485 	while (buflen) {
486 		struct page *page;
487 		unsigned long pfn;
488 		phys_addr_t phys;
489 		void *__start;
490 
491 		/*
492 		 * If this is the first iteration or the address is not within
493 		 * the previous entry, search for a matching entry.
494 		 */
495 		if (!m || start < m->addr || start >= m->addr + m->size) {
496 			struct kcore_list *iter;
497 
498 			m = NULL;
499 			list_for_each_entry(iter, &kclist_head, list) {
500 				if (start >= iter->addr &&
501 				    start < iter->addr + iter->size) {
502 					m = iter;
503 					break;
504 				}
505 			}
506 		}
507 
508 		if (page_offline_frozen++ % MAX_ORDER_NR_PAGES == 0) {
509 			page_offline_thaw();
510 			cond_resched();
511 			page_offline_freeze();
512 		}
513 
514 		if (!m) {
515 			if (iov_iter_zero(tsz, iter) != tsz) {
516 				ret = -EFAULT;
517 				goto out;
518 			}
519 			goto skip;
520 		}
521 
522 		switch (m->type) {
523 		case KCORE_VMALLOC:
524 		{
525 			const char *src = (char *)start;
526 			size_t read = 0, left = tsz;
527 
528 			/*
529 			 * vmalloc uses spinlocks, so we optimistically try to
530 			 * read memory. If this fails, fault pages in and try
531 			 * again until we are done.
532 			 */
533 			while (true) {
534 				read += vread_iter(iter, src, left);
535 				if (read == tsz)
536 					break;
537 
538 				src += read;
539 				left -= read;
540 
541 				if (fault_in_iov_iter_writeable(iter, left)) {
542 					ret = -EFAULT;
543 					goto out;
544 				}
545 			}
546 			break;
547 		}
548 		case KCORE_USER:
549 			/* User page is handled prior to normal kernel page: */
550 			if (copy_to_iter((char *)start, tsz, iter) != tsz) {
551 				ret = -EFAULT;
552 				goto out;
553 			}
554 			break;
555 		case KCORE_RAM:
556 			phys = __pa(start);
557 			pfn =  phys >> PAGE_SHIFT;
558 			page = pfn_to_online_page(pfn);
559 
560 			/*
561 			 * Don't read offline sections, logically offline pages
562 			 * (e.g., inflated in a balloon), hwpoisoned pages,
563 			 * and explicitly excluded physical ranges.
564 			 */
565 			if (!page || PageOffline(page) ||
566 			    is_page_hwpoison(page) || !pfn_is_ram(pfn) ||
567 			    pfn_is_unaccepted_memory(pfn)) {
568 				if (iov_iter_zero(tsz, iter) != tsz) {
569 					ret = -EFAULT;
570 					goto out;
571 				}
572 				break;
573 			}
574 			fallthrough;
575 		case KCORE_VMEMMAP:
576 		case KCORE_TEXT:
577 			if (m->type == KCORE_RAM) {
578 				__start = kc_xlate_dev_mem_ptr(phys);
579 				if (!__start) {
580 					ret = -ENOMEM;
581 					if (iov_iter_zero(tsz, iter) != tsz)
582 						ret = -EFAULT;
583 					goto out;
584 				}
585 			} else {
586 				__start = (void *)start;
587 			}
588 
589 			/*
590 			 * Sadly we must use a bounce buffer here to be able to
591 			 * make use of copy_from_kernel_nofault(), as these
592 			 * memory regions might not always be mapped on all
593 			 * architectures.
594 			 */
595 			ret = copy_from_kernel_nofault(buf, __start, tsz);
596 			if (m->type == KCORE_RAM)
597 				kc_unxlate_dev_mem_ptr(phys, __start);
598 			if (ret) {
599 				if (iov_iter_zero(tsz, iter) != tsz) {
600 					ret = -EFAULT;
601 					goto out;
602 				}
603 			/*
604 			 * We know the bounce buffer is safe to copy from, so
605 			 * use _copy_to_iter() directly.
606 			 */
607 			} else if (_copy_to_iter(buf, tsz, iter) != tsz) {
608 				ret = -EFAULT;
609 				goto out;
610 			}
611 			break;
612 		default:
613 			pr_warn_once("Unhandled KCORE type: %d\n", m->type);
614 			if (iov_iter_zero(tsz, iter) != tsz) {
615 				ret = -EFAULT;
616 				goto out;
617 			}
618 		}
619 skip:
620 		buflen -= tsz;
621 		*fpos += tsz;
622 		start += tsz;
623 		tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
624 	}
625 
626 out:
627 	page_offline_thaw();
628 	up_read(&kclist_lock);
629 	if (ret)
630 		return ret;
631 	return orig_buflen - buflen;
632 }
633 
634 static int open_kcore(struct inode *inode, struct file *filp)
635 {
636 	int ret = security_locked_down(LOCKDOWN_KCORE);
637 
638 	if (!capable(CAP_SYS_RAWIO))
639 		return -EPERM;
640 
641 	if (ret)
642 		return ret;
643 
644 	filp->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
645 	if (!filp->private_data)
646 		return -ENOMEM;
647 
648 	if (kcore_need_update)
649 		kcore_update_ram();
650 	if (i_size_read(inode) != proc_root_kcore->size) {
651 		inode_lock(inode);
652 		i_size_write(inode, proc_root_kcore->size);
653 		inode_unlock(inode);
654 	}
655 	return 0;
656 }
657 
658 static int release_kcore(struct inode *inode, struct file *file)
659 {
660 	kfree(file->private_data);
661 	return 0;
662 }
663 
664 static const struct proc_ops kcore_proc_ops = {
665 	.proc_read_iter	= read_kcore_iter,
666 	.proc_open	= open_kcore,
667 	.proc_release	= release_kcore,
668 	.proc_lseek	= default_llseek,
669 };
670 
671 /* just remember that we have to update kcore */
672 static int __meminit kcore_callback(struct notifier_block *self,
673 				    unsigned long action, void *arg)
674 {
675 	switch (action) {
676 	case MEM_ONLINE:
677 	case MEM_OFFLINE:
678 		kcore_need_update = 1;
679 		break;
680 	}
681 	return NOTIFY_OK;
682 }
683 
684 
685 static struct kcore_list kcore_vmalloc;
686 
687 #ifdef CONFIG_ARCH_PROC_KCORE_TEXT
688 static struct kcore_list kcore_text;
689 /*
690  * If defined, special segment is used for mapping kernel text instead of
691  * direct-map area. We need to create special TEXT section.
692  */
693 static void __init proc_kcore_text_init(void)
694 {
695 	kclist_add(&kcore_text, _text, _end - _text, KCORE_TEXT);
696 }
697 #else
698 static void __init proc_kcore_text_init(void)
699 {
700 }
701 #endif
702 
703 #if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
704 /*
705  * MODULES_VADDR has no intersection with VMALLOC_ADDR.
706  */
707 static struct kcore_list kcore_modules;
708 static void __init add_modules_range(void)
709 {
710 	if (MODULES_VADDR != VMALLOC_START && MODULES_END != VMALLOC_END) {
711 		kclist_add(&kcore_modules, (void *)MODULES_VADDR,
712 			MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
713 	}
714 }
715 #else
716 static void __init add_modules_range(void)
717 {
718 }
719 #endif
720 
721 static int __init proc_kcore_init(void)
722 {
723 	proc_root_kcore = proc_create("kcore", S_IRUSR, NULL, &kcore_proc_ops);
724 	if (!proc_root_kcore) {
725 		pr_err("couldn't create /proc/kcore\n");
726 		return 0; /* Always returns 0. */
727 	}
728 	/* Store text area if it's special */
729 	proc_kcore_text_init();
730 	/* Store vmalloc area */
731 	kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
732 		VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
733 	add_modules_range();
734 	/* Store direct-map area from physical memory map */
735 	kcore_update_ram();
736 	hotplug_memory_notifier(kcore_callback, DEFAULT_CALLBACK_PRI);
737 
738 	return 0;
739 }
740 fs_initcall(proc_kcore_init);
741