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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * kexec.c - kexec system call core code.
4 * Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com>
5 */
6
7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8
9#include <linux/capability.h>
10#include <linux/mm.h>
11#include <linux/file.h>
12#include <linux/slab.h>
13#include <linux/fs.h>
14#include <linux/kexec.h>
15#include <linux/mutex.h>
16#include <linux/list.h>
17#include <linux/highmem.h>
18#include <linux/syscalls.h>
19#include <linux/reboot.h>
20#include <linux/ioport.h>
21#include <linux/hardirq.h>
22#include <linux/elf.h>
23#include <linux/elfcore.h>
24#include <linux/utsname.h>
25#include <linux/numa.h>
26#include <linux/suspend.h>
27#include <linux/device.h>
28#include <linux/freezer.h>
29#include <linux/panic_notifier.h>
30#include <linux/pm.h>
31#include <linux/cpu.h>
32#include <linux/uaccess.h>
33#include <linux/io.h>
34#include <linux/console.h>
35#include <linux/vmalloc.h>
36#include <linux/swap.h>
37#include <linux/syscore_ops.h>
38#include <linux/compiler.h>
39#include <linux/hugetlb.h>
40#include <linux/objtool.h>
41#include <linux/kmsg_dump.h>
42
43#include <asm/page.h>
44#include <asm/sections.h>
45
46#include <crypto/hash.h>
47#include "kexec_internal.h"
48
49atomic_t __kexec_lock = ATOMIC_INIT(0);
50
51/* Per cpu memory for storing cpu states in case of system crash. */
52note_buf_t __percpu *crash_notes;
53
54/* Flag to indicate we are going to kexec a new kernel */
55bool kexec_in_progress = false;
56
57
58/* Location of the reserved area for the crash kernel */
59struct resource crashk_res = {
60 .name = "Crash kernel",
61 .start = 0,
62 .end = 0,
63 .flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
64 .desc = IORES_DESC_CRASH_KERNEL
65};
66struct resource crashk_low_res = {
67 .name = "Crash kernel",
68 .start = 0,
69 .end = 0,
70 .flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
71 .desc = IORES_DESC_CRASH_KERNEL
72};
73
74int kexec_should_crash(struct task_struct *p)
75{
76 /*
77 * If crash_kexec_post_notifiers is enabled, don't run
78 * crash_kexec() here yet, which must be run after panic
79 * notifiers in panic().
80 */
81 if (crash_kexec_post_notifiers)
82 return 0;
83 /*
84 * There are 4 panic() calls in make_task_dead() path, each of which
85 * corresponds to each of these 4 conditions.
86 */
87 if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops)
88 return 1;
89 return 0;
90}
91
92int kexec_crash_loaded(void)
93{
94 return !!kexec_crash_image;
95}
96EXPORT_SYMBOL_GPL(kexec_crash_loaded);
97
98/*
99 * When kexec transitions to the new kernel there is a one-to-one
100 * mapping between physical and virtual addresses. On processors
101 * where you can disable the MMU this is trivial, and easy. For
102 * others it is still a simple predictable page table to setup.
103 *
104 * In that environment kexec copies the new kernel to its final
105 * resting place. This means I can only support memory whose
106 * physical address can fit in an unsigned long. In particular
107 * addresses where (pfn << PAGE_SHIFT) > ULONG_MAX cannot be handled.
108 * If the assembly stub has more restrictive requirements
109 * KEXEC_SOURCE_MEMORY_LIMIT and KEXEC_DEST_MEMORY_LIMIT can be
110 * defined more restrictively in <asm/kexec.h>.
111 *
112 * The code for the transition from the current kernel to the
113 * new kernel is placed in the control_code_buffer, whose size
114 * is given by KEXEC_CONTROL_PAGE_SIZE. In the best case only a single
115 * page of memory is necessary, but some architectures require more.
116 * Because this memory must be identity mapped in the transition from
117 * virtual to physical addresses it must live in the range
118 * 0 - TASK_SIZE, as only the user space mappings are arbitrarily
119 * modifiable.
120 *
121 * The assembly stub in the control code buffer is passed a linked list
122 * of descriptor pages detailing the source pages of the new kernel,
123 * and the destination addresses of those source pages. As this data
124 * structure is not used in the context of the current OS, it must
125 * be self-contained.
126 *
127 * The code has been made to work with highmem pages and will use a
128 * destination page in its final resting place (if it happens
129 * to allocate it). The end product of this is that most of the
130 * physical address space, and most of RAM can be used.
131 *
132 * Future directions include:
133 * - allocating a page table with the control code buffer identity
134 * mapped, to simplify machine_kexec and make kexec_on_panic more
135 * reliable.
136 */
137
138/*
139 * KIMAGE_NO_DEST is an impossible destination address..., for
140 * allocating pages whose destination address we do not care about.
141 */
142#define KIMAGE_NO_DEST (-1UL)
143#define PAGE_COUNT(x) (((x) + PAGE_SIZE - 1) >> PAGE_SHIFT)
144
145static struct page *kimage_alloc_page(struct kimage *image,
146 gfp_t gfp_mask,
147 unsigned long dest);
148
149int sanity_check_segment_list(struct kimage *image)
150{
151 int i;
152 unsigned long nr_segments = image->nr_segments;
153 unsigned long total_pages = 0;
154 unsigned long nr_pages = totalram_pages();
155
156 /*
157 * Verify we have good destination addresses. The caller is
158 * responsible for making certain we don't attempt to load
159 * the new image into invalid or reserved areas of RAM. This
160 * just verifies it is an address we can use.
161 *
162 * Since the kernel does everything in page size chunks ensure
163 * the destination addresses are page aligned. Too many
164 * special cases crop of when we don't do this. The most
165 * insidious is getting overlapping destination addresses
166 * simply because addresses are changed to page size
167 * granularity.
168 */
169 for (i = 0; i < nr_segments; i++) {
170 unsigned long mstart, mend;
171
172 mstart = image->segment[i].mem;
173 mend = mstart + image->segment[i].memsz;
174 if (mstart > mend)
175 return -EADDRNOTAVAIL;
176 if ((mstart & ~PAGE_MASK) || (mend & ~PAGE_MASK))
177 return -EADDRNOTAVAIL;
178 if (mend >= KEXEC_DESTINATION_MEMORY_LIMIT)
179 return -EADDRNOTAVAIL;
180 }
181
182 /* Verify our destination addresses do not overlap.
183 * If we alloed overlapping destination addresses
184 * through very weird things can happen with no
185 * easy explanation as one segment stops on another.
186 */
187 for (i = 0; i < nr_segments; i++) {
188 unsigned long mstart, mend;
189 unsigned long j;
190
191 mstart = image->segment[i].mem;
192 mend = mstart + image->segment[i].memsz;
193 for (j = 0; j < i; j++) {
194 unsigned long pstart, pend;
195
196 pstart = image->segment[j].mem;
197 pend = pstart + image->segment[j].memsz;
198 /* Do the segments overlap ? */
199 if ((mend > pstart) && (mstart < pend))
200 return -EINVAL;
201 }
202 }
203
204 /* Ensure our buffer sizes are strictly less than
205 * our memory sizes. This should always be the case,
206 * and it is easier to check up front than to be surprised
207 * later on.
208 */
209 for (i = 0; i < nr_segments; i++) {
210 if (image->segment[i].bufsz > image->segment[i].memsz)
211 return -EINVAL;
212 }
213
214 /*
215 * Verify that no more than half of memory will be consumed. If the
216 * request from userspace is too large, a large amount of time will be
217 * wasted allocating pages, which can cause a soft lockup.
218 */
219 for (i = 0; i < nr_segments; i++) {
220 if (PAGE_COUNT(image->segment[i].memsz) > nr_pages / 2)
221 return -EINVAL;
222
223 total_pages += PAGE_COUNT(image->segment[i].memsz);
224 }
225
226 if (total_pages > nr_pages / 2)
227 return -EINVAL;
228
229 /*
230 * Verify we have good destination addresses. Normally
231 * the caller is responsible for making certain we don't
232 * attempt to load the new image into invalid or reserved
233 * areas of RAM. But crash kernels are preloaded into a
234 * reserved area of ram. We must ensure the addresses
235 * are in the reserved area otherwise preloading the
236 * kernel could corrupt things.
237 */
238
239 if (image->type == KEXEC_TYPE_CRASH) {
240 for (i = 0; i < nr_segments; i++) {
241 unsigned long mstart, mend;
242
243 mstart = image->segment[i].mem;
244 mend = mstart + image->segment[i].memsz - 1;
245 /* Ensure we are within the crash kernel limits */
246 if ((mstart < phys_to_boot_phys(crashk_res.start)) ||
247 (mend > phys_to_boot_phys(crashk_res.end)))
248 return -EADDRNOTAVAIL;
249 }
250 }
251
252 return 0;
253}
254
255struct kimage *do_kimage_alloc_init(void)
256{
257 struct kimage *image;
258
259 /* Allocate a controlling structure */
260 image = kzalloc(sizeof(*image), GFP_KERNEL);
261 if (!image)
262 return NULL;
263
264 image->head = 0;
265 image->entry = &image->head;
266 image->last_entry = &image->head;
267 image->control_page = ~0; /* By default this does not apply */
268 image->type = KEXEC_TYPE_DEFAULT;
269
270 /* Initialize the list of control pages */
271 INIT_LIST_HEAD(&image->control_pages);
272
273 /* Initialize the list of destination pages */
274 INIT_LIST_HEAD(&image->dest_pages);
275
276 /* Initialize the list of unusable pages */
277 INIT_LIST_HEAD(&image->unusable_pages);
278
279 return image;
280}
281
282int kimage_is_destination_range(struct kimage *image,
283 unsigned long start,
284 unsigned long end)
285{
286 unsigned long i;
287
288 for (i = 0; i < image->nr_segments; i++) {
289 unsigned long mstart, mend;
290
291 mstart = image->segment[i].mem;
292 mend = mstart + image->segment[i].memsz;
293 if ((end > mstart) && (start < mend))
294 return 1;
295 }
296
297 return 0;
298}
299
300static struct page *kimage_alloc_pages(gfp_t gfp_mask, unsigned int order)
301{
302 struct page *pages;
303
304 if (fatal_signal_pending(current))
305 return NULL;
306 pages = alloc_pages(gfp_mask & ~__GFP_ZERO, order);
307 if (pages) {
308 unsigned int count, i;
309
310 pages->mapping = NULL;
311 set_page_private(pages, order);
312 count = 1 << order;
313 for (i = 0; i < count; i++)
314 SetPageReserved(pages + i);
315
316 arch_kexec_post_alloc_pages(page_address(pages), count,
317 gfp_mask);
318
319 if (gfp_mask & __GFP_ZERO)
320 for (i = 0; i < count; i++)
321 clear_highpage(pages + i);
322 }
323
324 return pages;
325}
326
327static void kimage_free_pages(struct page *page)
328{
329 unsigned int order, count, i;
330
331 order = page_private(page);
332 count = 1 << order;
333
334 arch_kexec_pre_free_pages(page_address(page), count);
335
336 for (i = 0; i < count; i++)
337 ClearPageReserved(page + i);
338 __free_pages(page, order);
339}
340
341void kimage_free_page_list(struct list_head *list)
342{
343 struct page *page, *next;
344
345 list_for_each_entry_safe(page, next, list, lru) {
346 list_del(&page->lru);
347 kimage_free_pages(page);
348 }
349}
350
351static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
352 unsigned int order)
353{
354 /* Control pages are special, they are the intermediaries
355 * that are needed while we copy the rest of the pages
356 * to their final resting place. As such they must
357 * not conflict with either the destination addresses
358 * or memory the kernel is already using.
359 *
360 * The only case where we really need more than one of
361 * these are for architectures where we cannot disable
362 * the MMU and must instead generate an identity mapped
363 * page table for all of the memory.
364 *
365 * At worst this runs in O(N) of the image size.
366 */
367 struct list_head extra_pages;
368 struct page *pages;
369 unsigned int count;
370
371 count = 1 << order;
372 INIT_LIST_HEAD(&extra_pages);
373
374 /* Loop while I can allocate a page and the page allocated
375 * is a destination page.
376 */
377 do {
378 unsigned long pfn, epfn, addr, eaddr;
379
380 pages = kimage_alloc_pages(KEXEC_CONTROL_MEMORY_GFP, order);
381 if (!pages)
382 break;
383 pfn = page_to_boot_pfn(pages);
384 epfn = pfn + count;
385 addr = pfn << PAGE_SHIFT;
386 eaddr = epfn << PAGE_SHIFT;
387 if ((epfn >= (KEXEC_CONTROL_MEMORY_LIMIT >> PAGE_SHIFT)) ||
388 kimage_is_destination_range(image, addr, eaddr)) {
389 list_add(&pages->lru, &extra_pages);
390 pages = NULL;
391 }
392 } while (!pages);
393
394 if (pages) {
395 /* Remember the allocated page... */
396 list_add(&pages->lru, &image->control_pages);
397
398 /* Because the page is already in it's destination
399 * location we will never allocate another page at
400 * that address. Therefore kimage_alloc_pages
401 * will not return it (again) and we don't need
402 * to give it an entry in image->segment[].
403 */
404 }
405 /* Deal with the destination pages I have inadvertently allocated.
406 *
407 * Ideally I would convert multi-page allocations into single
408 * page allocations, and add everything to image->dest_pages.
409 *
410 * For now it is simpler to just free the pages.
411 */
412 kimage_free_page_list(&extra_pages);
413
414 return pages;
415}
416
417static struct page *kimage_alloc_crash_control_pages(struct kimage *image,
418 unsigned int order)
419{
420 /* Control pages are special, they are the intermediaries
421 * that are needed while we copy the rest of the pages
422 * to their final resting place. As such they must
423 * not conflict with either the destination addresses
424 * or memory the kernel is already using.
425 *
426 * Control pages are also the only pags we must allocate
427 * when loading a crash kernel. All of the other pages
428 * are specified by the segments and we just memcpy
429 * into them directly.
430 *
431 * The only case where we really need more than one of
432 * these are for architectures where we cannot disable
433 * the MMU and must instead generate an identity mapped
434 * page table for all of the memory.
435 *
436 * Given the low demand this implements a very simple
437 * allocator that finds the first hole of the appropriate
438 * size in the reserved memory region, and allocates all
439 * of the memory up to and including the hole.
440 */
441 unsigned long hole_start, hole_end, size;
442 struct page *pages;
443
444 pages = NULL;
445 size = (1 << order) << PAGE_SHIFT;
446 hole_start = (image->control_page + (size - 1)) & ~(size - 1);
447 hole_end = hole_start + size - 1;
448 while (hole_end <= crashk_res.end) {
449 unsigned long i;
450
451 cond_resched();
452
453 if (hole_end > KEXEC_CRASH_CONTROL_MEMORY_LIMIT)
454 break;
455 /* See if I overlap any of the segments */
456 for (i = 0; i < image->nr_segments; i++) {
457 unsigned long mstart, mend;
458
459 mstart = image->segment[i].mem;
460 mend = mstart + image->segment[i].memsz - 1;
461 if ((hole_end >= mstart) && (hole_start <= mend)) {
462 /* Advance the hole to the end of the segment */
463 hole_start = (mend + (size - 1)) & ~(size - 1);
464 hole_end = hole_start + size - 1;
465 break;
466 }
467 }
468 /* If I don't overlap any segments I have found my hole! */
469 if (i == image->nr_segments) {
470 pages = pfn_to_page(hole_start >> PAGE_SHIFT);
471 image->control_page = hole_end;
472 break;
473 }
474 }
475
476 /* Ensure that these pages are decrypted if SME is enabled. */
477 if (pages)
478 arch_kexec_post_alloc_pages(page_address(pages), 1 << order, 0);
479
480 return pages;
481}
482
483
484struct page *kimage_alloc_control_pages(struct kimage *image,
485 unsigned int order)
486{
487 struct page *pages = NULL;
488
489 switch (image->type) {
490 case KEXEC_TYPE_DEFAULT:
491 pages = kimage_alloc_normal_control_pages(image, order);
492 break;
493 case KEXEC_TYPE_CRASH:
494 pages = kimage_alloc_crash_control_pages(image, order);
495 break;
496 }
497
498 return pages;
499}
500
501int kimage_crash_copy_vmcoreinfo(struct kimage *image)
502{
503 struct page *vmcoreinfo_page;
504 void *safecopy;
505
506 if (image->type != KEXEC_TYPE_CRASH)
507 return 0;
508
509 /*
510 * For kdump, allocate one vmcoreinfo safe copy from the
511 * crash memory. as we have arch_kexec_protect_crashkres()
512 * after kexec syscall, we naturally protect it from write
513 * (even read) access under kernel direct mapping. But on
514 * the other hand, we still need to operate it when crash
515 * happens to generate vmcoreinfo note, hereby we rely on
516 * vmap for this purpose.
517 */
518 vmcoreinfo_page = kimage_alloc_control_pages(image, 0);
519 if (!vmcoreinfo_page) {
520 pr_warn("Could not allocate vmcoreinfo buffer\n");
521 return -ENOMEM;
522 }
523 safecopy = vmap(&vmcoreinfo_page, 1, VM_MAP, PAGE_KERNEL);
524 if (!safecopy) {
525 pr_warn("Could not vmap vmcoreinfo buffer\n");
526 return -ENOMEM;
527 }
528
529 image->vmcoreinfo_data_copy = safecopy;
530 crash_update_vmcoreinfo_safecopy(safecopy);
531
532 return 0;
533}
534
535static int kimage_add_entry(struct kimage *image, kimage_entry_t entry)
536{
537 if (*image->entry != 0)
538 image->entry++;
539
540 if (image->entry == image->last_entry) {
541 kimage_entry_t *ind_page;
542 struct page *page;
543
544 page = kimage_alloc_page(image, GFP_KERNEL, KIMAGE_NO_DEST);
545 if (!page)
546 return -ENOMEM;
547
548 ind_page = page_address(page);
549 *image->entry = virt_to_boot_phys(ind_page) | IND_INDIRECTION;
550 image->entry = ind_page;
551 image->last_entry = ind_page +
552 ((PAGE_SIZE/sizeof(kimage_entry_t)) - 1);
553 }
554 *image->entry = entry;
555 image->entry++;
556 *image->entry = 0;
557
558 return 0;
559}
560
561static int kimage_set_destination(struct kimage *image,
562 unsigned long destination)
563{
564 destination &= PAGE_MASK;
565
566 return kimage_add_entry(image, destination | IND_DESTINATION);
567}
568
569
570static int kimage_add_page(struct kimage *image, unsigned long page)
571{
572 page &= PAGE_MASK;
573
574 return kimage_add_entry(image, page | IND_SOURCE);
575}
576
577
578static void kimage_free_extra_pages(struct kimage *image)
579{
580 /* Walk through and free any extra destination pages I may have */
581 kimage_free_page_list(&image->dest_pages);
582
583 /* Walk through and free any unusable pages I have cached */
584 kimage_free_page_list(&image->unusable_pages);
585
586}
587
588void kimage_terminate(struct kimage *image)
589{
590 if (*image->entry != 0)
591 image->entry++;
592
593 *image->entry = IND_DONE;
594}
595
596#define for_each_kimage_entry(image, ptr, entry) \
597 for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); \
598 ptr = (entry & IND_INDIRECTION) ? \
599 boot_phys_to_virt((entry & PAGE_MASK)) : ptr + 1)
600
601static void kimage_free_entry(kimage_entry_t entry)
602{
603 struct page *page;
604
605 page = boot_pfn_to_page(entry >> PAGE_SHIFT);
606 kimage_free_pages(page);
607}
608
609void kimage_free(struct kimage *image)
610{
611 kimage_entry_t *ptr, entry;
612 kimage_entry_t ind = 0;
613
614 if (!image)
615 return;
616
617 if (image->vmcoreinfo_data_copy) {
618 crash_update_vmcoreinfo_safecopy(NULL);
619 vunmap(image->vmcoreinfo_data_copy);
620 }
621
622 kimage_free_extra_pages(image);
623 for_each_kimage_entry(image, ptr, entry) {
624 if (entry & IND_INDIRECTION) {
625 /* Free the previous indirection page */
626 if (ind & IND_INDIRECTION)
627 kimage_free_entry(ind);
628 /* Save this indirection page until we are
629 * done with it.
630 */
631 ind = entry;
632 } else if (entry & IND_SOURCE)
633 kimage_free_entry(entry);
634 }
635 /* Free the final indirection page */
636 if (ind & IND_INDIRECTION)
637 kimage_free_entry(ind);
638
639 /* Handle any machine specific cleanup */
640 machine_kexec_cleanup(image);
641
642 /* Free the kexec control pages... */
643 kimage_free_page_list(&image->control_pages);
644
645 /*
646 * Free up any temporary buffers allocated. This might hit if
647 * error occurred much later after buffer allocation.
648 */
649 if (image->file_mode)
650 kimage_file_post_load_cleanup(image);
651
652 kfree(image);
653}
654
655static kimage_entry_t *kimage_dst_used(struct kimage *image,
656 unsigned long page)
657{
658 kimage_entry_t *ptr, entry;
659 unsigned long destination = 0;
660
661 for_each_kimage_entry(image, ptr, entry) {
662 if (entry & IND_DESTINATION)
663 destination = entry & PAGE_MASK;
664 else if (entry & IND_SOURCE) {
665 if (page == destination)
666 return ptr;
667 destination += PAGE_SIZE;
668 }
669 }
670
671 return NULL;
672}
673
674static struct page *kimage_alloc_page(struct kimage *image,
675 gfp_t gfp_mask,
676 unsigned long destination)
677{
678 /*
679 * Here we implement safeguards to ensure that a source page
680 * is not copied to its destination page before the data on
681 * the destination page is no longer useful.
682 *
683 * To do this we maintain the invariant that a source page is
684 * either its own destination page, or it is not a
685 * destination page at all.
686 *
687 * That is slightly stronger than required, but the proof
688 * that no problems will not occur is trivial, and the
689 * implementation is simply to verify.
690 *
691 * When allocating all pages normally this algorithm will run
692 * in O(N) time, but in the worst case it will run in O(N^2)
693 * time. If the runtime is a problem the data structures can
694 * be fixed.
695 */
696 struct page *page;
697 unsigned long addr;
698
699 /*
700 * Walk through the list of destination pages, and see if I
701 * have a match.
702 */
703 list_for_each_entry(page, &image->dest_pages, lru) {
704 addr = page_to_boot_pfn(page) << PAGE_SHIFT;
705 if (addr == destination) {
706 list_del(&page->lru);
707 return page;
708 }
709 }
710 page = NULL;
711 while (1) {
712 kimage_entry_t *old;
713
714 /* Allocate a page, if we run out of memory give up */
715 page = kimage_alloc_pages(gfp_mask, 0);
716 if (!page)
717 return NULL;
718 /* If the page cannot be used file it away */
719 if (page_to_boot_pfn(page) >
720 (KEXEC_SOURCE_MEMORY_LIMIT >> PAGE_SHIFT)) {
721 list_add(&page->lru, &image->unusable_pages);
722 continue;
723 }
724 addr = page_to_boot_pfn(page) << PAGE_SHIFT;
725
726 /* If it is the destination page we want use it */
727 if (addr == destination)
728 break;
729
730 /* If the page is not a destination page use it */
731 if (!kimage_is_destination_range(image, addr,
732 addr + PAGE_SIZE))
733 break;
734
735 /*
736 * I know that the page is someones destination page.
737 * See if there is already a source page for this
738 * destination page. And if so swap the source pages.
739 */
740 old = kimage_dst_used(image, addr);
741 if (old) {
742 /* If so move it */
743 unsigned long old_addr;
744 struct page *old_page;
745
746 old_addr = *old & PAGE_MASK;
747 old_page = boot_pfn_to_page(old_addr >> PAGE_SHIFT);
748 copy_highpage(page, old_page);
749 *old = addr | (*old & ~PAGE_MASK);
750
751 /* The old page I have found cannot be a
752 * destination page, so return it if it's
753 * gfp_flags honor the ones passed in.
754 */
755 if (!(gfp_mask & __GFP_HIGHMEM) &&
756 PageHighMem(old_page)) {
757 kimage_free_pages(old_page);
758 continue;
759 }
760 page = old_page;
761 break;
762 }
763 /* Place the page on the destination list, to be used later */
764 list_add(&page->lru, &image->dest_pages);
765 }
766
767 return page;
768}
769
770static int kimage_load_normal_segment(struct kimage *image,
771 struct kexec_segment *segment)
772{
773 unsigned long maddr;
774 size_t ubytes, mbytes;
775 int result;
776 unsigned char __user *buf = NULL;
777 unsigned char *kbuf = NULL;
778
779 if (image->file_mode)
780 kbuf = segment->kbuf;
781 else
782 buf = segment->buf;
783 ubytes = segment->bufsz;
784 mbytes = segment->memsz;
785 maddr = segment->mem;
786
787 result = kimage_set_destination(image, maddr);
788 if (result < 0)
789 goto out;
790
791 while (mbytes) {
792 struct page *page;
793 char *ptr;
794 size_t uchunk, mchunk;
795
796 page = kimage_alloc_page(image, GFP_HIGHUSER, maddr);
797 if (!page) {
798 result = -ENOMEM;
799 goto out;
800 }
801 result = kimage_add_page(image, page_to_boot_pfn(page)
802 << PAGE_SHIFT);
803 if (result < 0)
804 goto out;
805
806 ptr = kmap_local_page(page);
807 /* Start with a clear page */
808 clear_page(ptr);
809 ptr += maddr & ~PAGE_MASK;
810 mchunk = min_t(size_t, mbytes,
811 PAGE_SIZE - (maddr & ~PAGE_MASK));
812 uchunk = min(ubytes, mchunk);
813
814 /* For file based kexec, source pages are in kernel memory */
815 if (image->file_mode)
816 memcpy(ptr, kbuf, uchunk);
817 else
818 result = copy_from_user(ptr, buf, uchunk);
819 kunmap_local(ptr);
820 if (result) {
821 result = -EFAULT;
822 goto out;
823 }
824 ubytes -= uchunk;
825 maddr += mchunk;
826 if (image->file_mode)
827 kbuf += mchunk;
828 else
829 buf += mchunk;
830 mbytes -= mchunk;
831
832 cond_resched();
833 }
834out:
835 return result;
836}
837
838static int kimage_load_crash_segment(struct kimage *image,
839 struct kexec_segment *segment)
840{
841 /* For crash dumps kernels we simply copy the data from
842 * user space to it's destination.
843 * We do things a page at a time for the sake of kmap.
844 */
845 unsigned long maddr;
846 size_t ubytes, mbytes;
847 int result;
848 unsigned char __user *buf = NULL;
849 unsigned char *kbuf = NULL;
850
851 result = 0;
852 if (image->file_mode)
853 kbuf = segment->kbuf;
854 else
855 buf = segment->buf;
856 ubytes = segment->bufsz;
857 mbytes = segment->memsz;
858 maddr = segment->mem;
859 while (mbytes) {
860 struct page *page;
861 char *ptr;
862 size_t uchunk, mchunk;
863
864 page = boot_pfn_to_page(maddr >> PAGE_SHIFT);
865 if (!page) {
866 result = -ENOMEM;
867 goto out;
868 }
869 arch_kexec_post_alloc_pages(page_address(page), 1, 0);
870 ptr = kmap_local_page(page);
871 ptr += maddr & ~PAGE_MASK;
872 mchunk = min_t(size_t, mbytes,
873 PAGE_SIZE - (maddr & ~PAGE_MASK));
874 uchunk = min(ubytes, mchunk);
875 if (mchunk > uchunk) {
876 /* Zero the trailing part of the page */
877 memset(ptr + uchunk, 0, mchunk - uchunk);
878 }
879
880 /* For file based kexec, source pages are in kernel memory */
881 if (image->file_mode)
882 memcpy(ptr, kbuf, uchunk);
883 else
884 result = copy_from_user(ptr, buf, uchunk);
885 kexec_flush_icache_page(page);
886 kunmap_local(ptr);
887 arch_kexec_pre_free_pages(page_address(page), 1);
888 if (result) {
889 result = -EFAULT;
890 goto out;
891 }
892 ubytes -= uchunk;
893 maddr += mchunk;
894 if (image->file_mode)
895 kbuf += mchunk;
896 else
897 buf += mchunk;
898 mbytes -= mchunk;
899
900 cond_resched();
901 }
902out:
903 return result;
904}
905
906int kimage_load_segment(struct kimage *image,
907 struct kexec_segment *segment)
908{
909 int result = -ENOMEM;
910
911 switch (image->type) {
912 case KEXEC_TYPE_DEFAULT:
913 result = kimage_load_normal_segment(image, segment);
914 break;
915 case KEXEC_TYPE_CRASH:
916 result = kimage_load_crash_segment(image, segment);
917 break;
918 }
919
920 return result;
921}
922
923struct kimage *kexec_image;
924struct kimage *kexec_crash_image;
925int kexec_load_disabled;
926#ifdef CONFIG_SYSCTL
927static struct ctl_table kexec_core_sysctls[] = {
928 {
929 .procname = "kexec_load_disabled",
930 .data = &kexec_load_disabled,
931 .maxlen = sizeof(int),
932 .mode = 0644,
933 /* only handle a transition from default "0" to "1" */
934 .proc_handler = proc_dointvec_minmax,
935 .extra1 = SYSCTL_ONE,
936 .extra2 = SYSCTL_ONE,
937 },
938 { }
939};
940
941static int __init kexec_core_sysctl_init(void)
942{
943 register_sysctl_init("kernel", kexec_core_sysctls);
944 return 0;
945}
946late_initcall(kexec_core_sysctl_init);
947#endif
948
949/*
950 * No panic_cpu check version of crash_kexec(). This function is called
951 * only when panic_cpu holds the current CPU number; this is the only CPU
952 * which processes crash_kexec routines.
953 */
954void __noclone __crash_kexec(struct pt_regs *regs)
955{
956 /* Take the kexec_lock here to prevent sys_kexec_load
957 * running on one cpu from replacing the crash kernel
958 * we are using after a panic on a different cpu.
959 *
960 * If the crash kernel was not located in a fixed area
961 * of memory the xchg(&kexec_crash_image) would be
962 * sufficient. But since I reuse the memory...
963 */
964 if (kexec_trylock()) {
965 if (kexec_crash_image) {
966 struct pt_regs fixed_regs;
967
968 crash_setup_regs(&fixed_regs, regs);
969 crash_save_vmcoreinfo();
970 machine_crash_shutdown(&fixed_regs);
971 machine_kexec(kexec_crash_image);
972 }
973 kexec_unlock();
974 }
975}
976STACK_FRAME_NON_STANDARD(__crash_kexec);
977
978void crash_kexec(struct pt_regs *regs)
979{
980 int old_cpu, this_cpu;
981
982 /*
983 * Only one CPU is allowed to execute the crash_kexec() code as with
984 * panic(). Otherwise parallel calls of panic() and crash_kexec()
985 * may stop each other. To exclude them, we use panic_cpu here too.
986 */
987 this_cpu = raw_smp_processor_id();
988 old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
989 if (old_cpu == PANIC_CPU_INVALID) {
990 /* This is the 1st CPU which comes here, so go ahead. */
991 __crash_kexec(regs);
992
993 /*
994 * Reset panic_cpu to allow another panic()/crash_kexec()
995 * call.
996 */
997 atomic_set(&panic_cpu, PANIC_CPU_INVALID);
998 }
999}
1000
1001ssize_t crash_get_memory_size(void)
1002{
1003 ssize_t size = 0;
1004
1005 if (!kexec_trylock())
1006 return -EBUSY;
1007
1008 if (crashk_res.end != crashk_res.start)
1009 size = resource_size(&crashk_res);
1010
1011 kexec_unlock();
1012 return size;
1013}
1014
1015int crash_shrink_memory(unsigned long new_size)
1016{
1017 int ret = 0;
1018 unsigned long start, end;
1019 unsigned long old_size;
1020 struct resource *ram_res;
1021
1022 if (!kexec_trylock())
1023 return -EBUSY;
1024
1025 if (kexec_crash_image) {
1026 ret = -ENOENT;
1027 goto unlock;
1028 }
1029 start = crashk_res.start;
1030 end = crashk_res.end;
1031 old_size = (end == 0) ? 0 : end - start + 1;
1032 if (new_size >= old_size) {
1033 ret = (new_size == old_size) ? 0 : -EINVAL;
1034 goto unlock;
1035 }
1036
1037 ram_res = kzalloc(sizeof(*ram_res), GFP_KERNEL);
1038 if (!ram_res) {
1039 ret = -ENOMEM;
1040 goto unlock;
1041 }
1042
1043 start = roundup(start, KEXEC_CRASH_MEM_ALIGN);
1044 end = roundup(start + new_size, KEXEC_CRASH_MEM_ALIGN);
1045
1046 crash_free_reserved_phys_range(end, crashk_res.end);
1047
1048 if ((start == end) && (crashk_res.parent != NULL))
1049 release_resource(&crashk_res);
1050
1051 ram_res->start = end;
1052 ram_res->end = crashk_res.end;
1053 ram_res->flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM;
1054 ram_res->name = "System RAM";
1055
1056 crashk_res.end = end - 1;
1057
1058 insert_resource(&iomem_resource, ram_res);
1059
1060unlock:
1061 kexec_unlock();
1062 return ret;
1063}
1064
1065void crash_save_cpu(struct pt_regs *regs, int cpu)
1066{
1067 struct elf_prstatus prstatus;
1068 u32 *buf;
1069
1070 if ((cpu < 0) || (cpu >= nr_cpu_ids))
1071 return;
1072
1073 /* Using ELF notes here is opportunistic.
1074 * I need a well defined structure format
1075 * for the data I pass, and I need tags
1076 * on the data to indicate what information I have
1077 * squirrelled away. ELF notes happen to provide
1078 * all of that, so there is no need to invent something new.
1079 */
1080 buf = (u32 *)per_cpu_ptr(crash_notes, cpu);
1081 if (!buf)
1082 return;
1083 memset(&prstatus, 0, sizeof(prstatus));
1084 prstatus.common.pr_pid = current->pid;
1085 elf_core_copy_regs(&prstatus.pr_reg, regs);
1086 buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS,
1087 &prstatus, sizeof(prstatus));
1088 final_note(buf);
1089}
1090
1091static int __init crash_notes_memory_init(void)
1092{
1093 /* Allocate memory for saving cpu registers. */
1094 size_t size, align;
1095
1096 /*
1097 * crash_notes could be allocated across 2 vmalloc pages when percpu
1098 * is vmalloc based . vmalloc doesn't guarantee 2 continuous vmalloc
1099 * pages are also on 2 continuous physical pages. In this case the
1100 * 2nd part of crash_notes in 2nd page could be lost since only the
1101 * starting address and size of crash_notes are exported through sysfs.
1102 * Here round up the size of crash_notes to the nearest power of two
1103 * and pass it to __alloc_percpu as align value. This can make sure
1104 * crash_notes is allocated inside one physical page.
1105 */
1106 size = sizeof(note_buf_t);
1107 align = min(roundup_pow_of_two(sizeof(note_buf_t)), PAGE_SIZE);
1108
1109 /*
1110 * Break compile if size is bigger than PAGE_SIZE since crash_notes
1111 * definitely will be in 2 pages with that.
1112 */
1113 BUILD_BUG_ON(size > PAGE_SIZE);
1114
1115 crash_notes = __alloc_percpu(size, align);
1116 if (!crash_notes) {
1117 pr_warn("Memory allocation for saving cpu register states failed\n");
1118 return -ENOMEM;
1119 }
1120 return 0;
1121}
1122subsys_initcall(crash_notes_memory_init);
1123
1124
1125/*
1126 * Move into place and start executing a preloaded standalone
1127 * executable. If nothing was preloaded return an error.
1128 */
1129int kernel_kexec(void)
1130{
1131 int error = 0;
1132
1133 if (!kexec_trylock())
1134 return -EBUSY;
1135 if (!kexec_image) {
1136 error = -EINVAL;
1137 goto Unlock;
1138 }
1139
1140#ifdef CONFIG_KEXEC_JUMP
1141 if (kexec_image->preserve_context) {
1142 pm_prepare_console();
1143 error = freeze_processes();
1144 if (error) {
1145 error = -EBUSY;
1146 goto Restore_console;
1147 }
1148 suspend_console();
1149 error = dpm_suspend_start(PMSG_FREEZE);
1150 if (error)
1151 goto Resume_console;
1152 /* At this point, dpm_suspend_start() has been called,
1153 * but *not* dpm_suspend_end(). We *must* call
1154 * dpm_suspend_end() now. Otherwise, drivers for
1155 * some devices (e.g. interrupt controllers) become
1156 * desynchronized with the actual state of the
1157 * hardware at resume time, and evil weirdness ensues.
1158 */
1159 error = dpm_suspend_end(PMSG_FREEZE);
1160 if (error)
1161 goto Resume_devices;
1162 error = suspend_disable_secondary_cpus();
1163 if (error)
1164 goto Enable_cpus;
1165 local_irq_disable();
1166 error = syscore_suspend();
1167 if (error)
1168 goto Enable_irqs;
1169 } else
1170#endif
1171 {
1172 kexec_in_progress = true;
1173 kernel_restart_prepare("kexec reboot");
1174 migrate_to_reboot_cpu();
1175
1176 /*
1177 * migrate_to_reboot_cpu() disables CPU hotplug assuming that
1178 * no further code needs to use CPU hotplug (which is true in
1179 * the reboot case). However, the kexec path depends on using
1180 * CPU hotplug again; so re-enable it here.
1181 */
1182 cpu_hotplug_enable();
1183 pr_notice("Starting new kernel\n");
1184 machine_shutdown();
1185 }
1186
1187 kmsg_dump(KMSG_DUMP_SHUTDOWN);
1188 machine_kexec(kexec_image);
1189
1190#ifdef CONFIG_KEXEC_JUMP
1191 if (kexec_image->preserve_context) {
1192 syscore_resume();
1193 Enable_irqs:
1194 local_irq_enable();
1195 Enable_cpus:
1196 suspend_enable_secondary_cpus();
1197 dpm_resume_start(PMSG_RESTORE);
1198 Resume_devices:
1199 dpm_resume_end(PMSG_RESTORE);
1200 Resume_console:
1201 resume_console();
1202 thaw_processes();
1203 Restore_console:
1204 pm_restore_console();
1205 }
1206#endif
1207
1208 Unlock:
1209 kexec_unlock();
1210 return error;
1211}