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Linux/kernel/kexec_core.c

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  1 /*
  2  * kexec.c - kexec system call core code.
  3  * Copyright (C) 2002-2004 Eric Biederman  <ebiederm@xmission.com>
  4  *
  5  * This source code is licensed under the GNU General Public License,
  6  * Version 2.  See the file COPYING for more details.
  7  */
  8 
  9 #define pr_fmt(fmt)     "kexec: " fmt
 10 
 11 #include <linux/capability.h>
 12 #include <linux/mm.h>
 13 #include <linux/file.h>
 14 #include <linux/slab.h>
 15 #include <linux/fs.h>
 16 #include <linux/kexec.h>
 17 #include <linux/mutex.h>
 18 #include <linux/list.h>
 19 #include <linux/highmem.h>
 20 #include <linux/syscalls.h>
 21 #include <linux/reboot.h>
 22 #include <linux/ioport.h>
 23 #include <linux/hardirq.h>
 24 #include <linux/elf.h>
 25 #include <linux/elfcore.h>
 26 #include <linux/utsname.h>
 27 #include <linux/numa.h>
 28 #include <linux/suspend.h>
 29 #include <linux/device.h>
 30 #include <linux/freezer.h>
 31 #include <linux/pm.h>
 32 #include <linux/cpu.h>
 33 #include <linux/uaccess.h>
 34 #include <linux/io.h>
 35 #include <linux/console.h>
 36 #include <linux/vmalloc.h>
 37 #include <linux/swap.h>
 38 #include <linux/syscore_ops.h>
 39 #include <linux/compiler.h>
 40 #include <linux/hugetlb.h>
 41 
 42 #include <asm/page.h>
 43 #include <asm/sections.h>
 44 
 45 #include <crypto/hash.h>
 46 #include <crypto/sha.h>
 47 #include "kexec_internal.h"
 48 
 49 DEFINE_MUTEX(kexec_mutex);
 50 
 51 /* Per cpu memory for storing cpu states in case of system crash. */
 52 note_buf_t __percpu *crash_notes;
 53 
 54 /* vmcoreinfo stuff */
 55 static unsigned char vmcoreinfo_data[VMCOREINFO_BYTES];
 56 u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
 57 size_t vmcoreinfo_size;
 58 size_t vmcoreinfo_max_size = sizeof(vmcoreinfo_data);
 59 
 60 /* Flag to indicate we are going to kexec a new kernel */
 61 bool kexec_in_progress = false;
 62 
 63 
 64 /* Location of the reserved area for the crash kernel */
 65 struct resource crashk_res = {
 66         .name  = "Crash kernel",
 67         .start = 0,
 68         .end   = 0,
 69         .flags = IORESOURCE_BUSY | IORESOURCE_MEM
 70 };
 71 struct resource crashk_low_res = {
 72         .name  = "Crash kernel",
 73         .start = 0,
 74         .end   = 0,
 75         .flags = IORESOURCE_BUSY | IORESOURCE_MEM
 76 };
 77 
 78 int kexec_should_crash(struct task_struct *p)
 79 {
 80         /*
 81          * If crash_kexec_post_notifiers is enabled, don't run
 82          * crash_kexec() here yet, which must be run after panic
 83          * notifiers in panic().
 84          */
 85         if (crash_kexec_post_notifiers)
 86                 return 0;
 87         /*
 88          * There are 4 panic() calls in do_exit() path, each of which
 89          * corresponds to each of these 4 conditions.
 90          */
 91         if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops)
 92                 return 1;
 93         return 0;
 94 }
 95 
 96 /*
 97  * When kexec transitions to the new kernel there is a one-to-one
 98  * mapping between physical and virtual addresses.  On processors
 99  * where you can disable the MMU this is trivial, and easy.  For
100  * others it is still a simple predictable page table to setup.
101  *
102  * In that environment kexec copies the new kernel to its final
103  * resting place.  This means I can only support memory whose
104  * physical address can fit in an unsigned long.  In particular
105  * addresses where (pfn << PAGE_SHIFT) > ULONG_MAX cannot be handled.
106  * If the assembly stub has more restrictive requirements
107  * KEXEC_SOURCE_MEMORY_LIMIT and KEXEC_DEST_MEMORY_LIMIT can be
108  * defined more restrictively in <asm/kexec.h>.
109  *
110  * The code for the transition from the current kernel to the
111  * the new kernel is placed in the control_code_buffer, whose size
112  * is given by KEXEC_CONTROL_PAGE_SIZE.  In the best case only a single
113  * page of memory is necessary, but some architectures require more.
114  * Because this memory must be identity mapped in the transition from
115  * virtual to physical addresses it must live in the range
116  * 0 - TASK_SIZE, as only the user space mappings are arbitrarily
117  * modifiable.
118  *
119  * The assembly stub in the control code buffer is passed a linked list
120  * of descriptor pages detailing the source pages of the new kernel,
121  * and the destination addresses of those source pages.  As this data
122  * structure is not used in the context of the current OS, it must
123  * be self-contained.
124  *
125  * The code has been made to work with highmem pages and will use a
126  * destination page in its final resting place (if it happens
127  * to allocate it).  The end product of this is that most of the
128  * physical address space, and most of RAM can be used.
129  *
130  * Future directions include:
131  *  - allocating a page table with the control code buffer identity
132  *    mapped, to simplify machine_kexec and make kexec_on_panic more
133  *    reliable.
134  */
135 
136 /*
137  * KIMAGE_NO_DEST is an impossible destination address..., for
138  * allocating pages whose destination address we do not care about.
139  */
140 #define KIMAGE_NO_DEST (-1UL)
141 
142 static struct page *kimage_alloc_page(struct kimage *image,
143                                        gfp_t gfp_mask,
144                                        unsigned long dest);
145 
146 int sanity_check_segment_list(struct kimage *image)
147 {
148         int result, i;
149         unsigned long nr_segments = image->nr_segments;
150 
151         /*
152          * Verify we have good destination addresses.  The caller is
153          * responsible for making certain we don't attempt to load
154          * the new image into invalid or reserved areas of RAM.  This
155          * just verifies it is an address we can use.
156          *
157          * Since the kernel does everything in page size chunks ensure
158          * the destination addresses are page aligned.  Too many
159          * special cases crop of when we don't do this.  The most
160          * insidious is getting overlapping destination addresses
161          * simply because addresses are changed to page size
162          * granularity.
163          */
164         result = -EADDRNOTAVAIL;
165         for (i = 0; i < nr_segments; i++) {
166                 unsigned long mstart, mend;
167 
168                 mstart = image->segment[i].mem;
169                 mend   = mstart + image->segment[i].memsz;
170                 if ((mstart & ~PAGE_MASK) || (mend & ~PAGE_MASK))
171                         return result;
172                 if (mend >= KEXEC_DESTINATION_MEMORY_LIMIT)
173                         return result;
174         }
175 
176         /* Verify our destination addresses do not overlap.
177          * If we alloed overlapping destination addresses
178          * through very weird things can happen with no
179          * easy explanation as one segment stops on another.
180          */
181         result = -EINVAL;
182         for (i = 0; i < nr_segments; i++) {
183                 unsigned long mstart, mend;
184                 unsigned long j;
185 
186                 mstart = image->segment[i].mem;
187                 mend   = mstart + image->segment[i].memsz;
188                 for (j = 0; j < i; j++) {
189                         unsigned long pstart, pend;
190 
191                         pstart = image->segment[j].mem;
192                         pend   = pstart + image->segment[j].memsz;
193                         /* Do the segments overlap ? */
194                         if ((mend > pstart) && (mstart < pend))
195                                 return result;
196                 }
197         }
198 
199         /* Ensure our buffer sizes are strictly less than
200          * our memory sizes.  This should always be the case,
201          * and it is easier to check up front than to be surprised
202          * later on.
203          */
204         result = -EINVAL;
205         for (i = 0; i < nr_segments; i++) {
206                 if (image->segment[i].bufsz > image->segment[i].memsz)
207                         return result;
208         }
209 
210         /*
211          * Verify we have good destination addresses.  Normally
212          * the caller is responsible for making certain we don't
213          * attempt to load the new image into invalid or reserved
214          * areas of RAM.  But crash kernels are preloaded into a
215          * reserved area of ram.  We must ensure the addresses
216          * are in the reserved area otherwise preloading the
217          * kernel could corrupt things.
218          */
219 
220         if (image->type == KEXEC_TYPE_CRASH) {
221                 result = -EADDRNOTAVAIL;
222                 for (i = 0; i < nr_segments; i++) {
223                         unsigned long mstart, mend;
224 
225                         mstart = image->segment[i].mem;
226                         mend = mstart + image->segment[i].memsz - 1;
227                         /* Ensure we are within the crash kernel limits */
228                         if ((mstart < crashk_res.start) ||
229                             (mend > crashk_res.end))
230                                 return result;
231                 }
232         }
233 
234         return 0;
235 }
236 
237 struct kimage *do_kimage_alloc_init(void)
238 {
239         struct kimage *image;
240 
241         /* Allocate a controlling structure */
242         image = kzalloc(sizeof(*image), GFP_KERNEL);
243         if (!image)
244                 return NULL;
245 
246         image->head = 0;
247         image->entry = &image->head;
248         image->last_entry = &image->head;
249         image->control_page = ~0; /* By default this does not apply */
250         image->type = KEXEC_TYPE_DEFAULT;
251 
252         /* Initialize the list of control pages */
253         INIT_LIST_HEAD(&image->control_pages);
254 
255         /* Initialize the list of destination pages */
256         INIT_LIST_HEAD(&image->dest_pages);
257 
258         /* Initialize the list of unusable pages */
259         INIT_LIST_HEAD(&image->unusable_pages);
260 
261         return image;
262 }
263 
264 int kimage_is_destination_range(struct kimage *image,
265                                         unsigned long start,
266                                         unsigned long end)
267 {
268         unsigned long i;
269 
270         for (i = 0; i < image->nr_segments; i++) {
271                 unsigned long mstart, mend;
272 
273                 mstart = image->segment[i].mem;
274                 mend = mstart + image->segment[i].memsz;
275                 if ((end > mstart) && (start < mend))
276                         return 1;
277         }
278 
279         return 0;
280 }
281 
282 static struct page *kimage_alloc_pages(gfp_t gfp_mask, unsigned int order)
283 {
284         struct page *pages;
285 
286         pages = alloc_pages(gfp_mask, order);
287         if (pages) {
288                 unsigned int count, i;
289 
290                 pages->mapping = NULL;
291                 set_page_private(pages, order);
292                 count = 1 << order;
293                 for (i = 0; i < count; i++)
294                         SetPageReserved(pages + i);
295         }
296 
297         return pages;
298 }
299 
300 static void kimage_free_pages(struct page *page)
301 {
302         unsigned int order, count, i;
303 
304         order = page_private(page);
305         count = 1 << order;
306         for (i = 0; i < count; i++)
307                 ClearPageReserved(page + i);
308         __free_pages(page, order);
309 }
310 
311 void kimage_free_page_list(struct list_head *list)
312 {
313         struct list_head *pos, *next;
314 
315         list_for_each_safe(pos, next, list) {
316                 struct page *page;
317 
318                 page = list_entry(pos, struct page, lru);
319                 list_del(&page->lru);
320                 kimage_free_pages(page);
321         }
322 }
323 
324 static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
325                                                         unsigned int order)
326 {
327         /* Control pages are special, they are the intermediaries
328          * that are needed while we copy the rest of the pages
329          * to their final resting place.  As such they must
330          * not conflict with either the destination addresses
331          * or memory the kernel is already using.
332          *
333          * The only case where we really need more than one of
334          * these are for architectures where we cannot disable
335          * the MMU and must instead generate an identity mapped
336          * page table for all of the memory.
337          *
338          * At worst this runs in O(N) of the image size.
339          */
340         struct list_head extra_pages;
341         struct page *pages;
342         unsigned int count;
343 
344         count = 1 << order;
345         INIT_LIST_HEAD(&extra_pages);
346 
347         /* Loop while I can allocate a page and the page allocated
348          * is a destination page.
349          */
350         do {
351                 unsigned long pfn, epfn, addr, eaddr;
352 
353                 pages = kimage_alloc_pages(KEXEC_CONTROL_MEMORY_GFP, order);
354                 if (!pages)
355                         break;
356                 pfn   = page_to_pfn(pages);
357                 epfn  = pfn + count;
358                 addr  = pfn << PAGE_SHIFT;
359                 eaddr = epfn << PAGE_SHIFT;
360                 if ((epfn >= (KEXEC_CONTROL_MEMORY_LIMIT >> PAGE_SHIFT)) ||
361                               kimage_is_destination_range(image, addr, eaddr)) {
362                         list_add(&pages->lru, &extra_pages);
363                         pages = NULL;
364                 }
365         } while (!pages);
366 
367         if (pages) {
368                 /* Remember the allocated page... */
369                 list_add(&pages->lru, &image->control_pages);
370 
371                 /* Because the page is already in it's destination
372                  * location we will never allocate another page at
373                  * that address.  Therefore kimage_alloc_pages
374                  * will not return it (again) and we don't need
375                  * to give it an entry in image->segment[].
376                  */
377         }
378         /* Deal with the destination pages I have inadvertently allocated.
379          *
380          * Ideally I would convert multi-page allocations into single
381          * page allocations, and add everything to image->dest_pages.
382          *
383          * For now it is simpler to just free the pages.
384          */
385         kimage_free_page_list(&extra_pages);
386 
387         return pages;
388 }
389 
390 static struct page *kimage_alloc_crash_control_pages(struct kimage *image,
391                                                       unsigned int order)
392 {
393         /* Control pages are special, they are the intermediaries
394          * that are needed while we copy the rest of the pages
395          * to their final resting place.  As such they must
396          * not conflict with either the destination addresses
397          * or memory the kernel is already using.
398          *
399          * Control pages are also the only pags we must allocate
400          * when loading a crash kernel.  All of the other pages
401          * are specified by the segments and we just memcpy
402          * into them directly.
403          *
404          * The only case where we really need more than one of
405          * these are for architectures where we cannot disable
406          * the MMU and must instead generate an identity mapped
407          * page table for all of the memory.
408          *
409          * Given the low demand this implements a very simple
410          * allocator that finds the first hole of the appropriate
411          * size in the reserved memory region, and allocates all
412          * of the memory up to and including the hole.
413          */
414         unsigned long hole_start, hole_end, size;
415         struct page *pages;
416 
417         pages = NULL;
418         size = (1 << order) << PAGE_SHIFT;
419         hole_start = (image->control_page + (size - 1)) & ~(size - 1);
420         hole_end   = hole_start + size - 1;
421         while (hole_end <= crashk_res.end) {
422                 unsigned long i;
423 
424                 if (hole_end > KEXEC_CRASH_CONTROL_MEMORY_LIMIT)
425                         break;
426                 /* See if I overlap any of the segments */
427                 for (i = 0; i < image->nr_segments; i++) {
428                         unsigned long mstart, mend;
429 
430                         mstart = image->segment[i].mem;
431                         mend   = mstart + image->segment[i].memsz - 1;
432                         if ((hole_end >= mstart) && (hole_start <= mend)) {
433                                 /* Advance the hole to the end of the segment */
434                                 hole_start = (mend + (size - 1)) & ~(size - 1);
435                                 hole_end   = hole_start + size - 1;
436                                 break;
437                         }
438                 }
439                 /* If I don't overlap any segments I have found my hole! */
440                 if (i == image->nr_segments) {
441                         pages = pfn_to_page(hole_start >> PAGE_SHIFT);
442                         image->control_page = hole_end;
443                         break;
444                 }
445         }
446 
447         return pages;
448 }
449 
450 
451 struct page *kimage_alloc_control_pages(struct kimage *image,
452                                          unsigned int order)
453 {
454         struct page *pages = NULL;
455 
456         switch (image->type) {
457         case KEXEC_TYPE_DEFAULT:
458                 pages = kimage_alloc_normal_control_pages(image, order);
459                 break;
460         case KEXEC_TYPE_CRASH:
461                 pages = kimage_alloc_crash_control_pages(image, order);
462                 break;
463         }
464 
465         return pages;
466 }
467 
468 static int kimage_add_entry(struct kimage *image, kimage_entry_t entry)
469 {
470         if (*image->entry != 0)
471                 image->entry++;
472 
473         if (image->entry == image->last_entry) {
474                 kimage_entry_t *ind_page;
475                 struct page *page;
476 
477                 page = kimage_alloc_page(image, GFP_KERNEL, KIMAGE_NO_DEST);
478                 if (!page)
479                         return -ENOMEM;
480 
481                 ind_page = page_address(page);
482                 *image->entry = virt_to_phys(ind_page) | IND_INDIRECTION;
483                 image->entry = ind_page;
484                 image->last_entry = ind_page +
485                                       ((PAGE_SIZE/sizeof(kimage_entry_t)) - 1);
486         }
487         *image->entry = entry;
488         image->entry++;
489         *image->entry = 0;
490 
491         return 0;
492 }
493 
494 static int kimage_set_destination(struct kimage *image,
495                                    unsigned long destination)
496 {
497         int result;
498 
499         destination &= PAGE_MASK;
500         result = kimage_add_entry(image, destination | IND_DESTINATION);
501 
502         return result;
503 }
504 
505 
506 static int kimage_add_page(struct kimage *image, unsigned long page)
507 {
508         int result;
509 
510         page &= PAGE_MASK;
511         result = kimage_add_entry(image, page | IND_SOURCE);
512 
513         return result;
514 }
515 
516 
517 static void kimage_free_extra_pages(struct kimage *image)
518 {
519         /* Walk through and free any extra destination pages I may have */
520         kimage_free_page_list(&image->dest_pages);
521 
522         /* Walk through and free any unusable pages I have cached */
523         kimage_free_page_list(&image->unusable_pages);
524 
525 }
526 void kimage_terminate(struct kimage *image)
527 {
528         if (*image->entry != 0)
529                 image->entry++;
530 
531         *image->entry = IND_DONE;
532 }
533 
534 #define for_each_kimage_entry(image, ptr, entry) \
535         for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); \
536                 ptr = (entry & IND_INDIRECTION) ? \
537                         phys_to_virt((entry & PAGE_MASK)) : ptr + 1)
538 
539 static void kimage_free_entry(kimage_entry_t entry)
540 {
541         struct page *page;
542 
543         page = pfn_to_page(entry >> PAGE_SHIFT);
544         kimage_free_pages(page);
545 }
546 
547 void kimage_free(struct kimage *image)
548 {
549         kimage_entry_t *ptr, entry;
550         kimage_entry_t ind = 0;
551 
552         if (!image)
553                 return;
554 
555         kimage_free_extra_pages(image);
556         for_each_kimage_entry(image, ptr, entry) {
557                 if (entry & IND_INDIRECTION) {
558                         /* Free the previous indirection page */
559                         if (ind & IND_INDIRECTION)
560                                 kimage_free_entry(ind);
561                         /* Save this indirection page until we are
562                          * done with it.
563                          */
564                         ind = entry;
565                 } else if (entry & IND_SOURCE)
566                         kimage_free_entry(entry);
567         }
568         /* Free the final indirection page */
569         if (ind & IND_INDIRECTION)
570                 kimage_free_entry(ind);
571 
572         /* Handle any machine specific cleanup */
573         machine_kexec_cleanup(image);
574 
575         /* Free the kexec control pages... */
576         kimage_free_page_list(&image->control_pages);
577 
578         /*
579          * Free up any temporary buffers allocated. This might hit if
580          * error occurred much later after buffer allocation.
581          */
582         if (image->file_mode)
583                 kimage_file_post_load_cleanup(image);
584 
585         kfree(image);
586 }
587 
588 static kimage_entry_t *kimage_dst_used(struct kimage *image,
589                                         unsigned long page)
590 {
591         kimage_entry_t *ptr, entry;
592         unsigned long destination = 0;
593 
594         for_each_kimage_entry(image, ptr, entry) {
595                 if (entry & IND_DESTINATION)
596                         destination = entry & PAGE_MASK;
597                 else if (entry & IND_SOURCE) {
598                         if (page == destination)
599                                 return ptr;
600                         destination += PAGE_SIZE;
601                 }
602         }
603 
604         return NULL;
605 }
606 
607 static struct page *kimage_alloc_page(struct kimage *image,
608                                         gfp_t gfp_mask,
609                                         unsigned long destination)
610 {
611         /*
612          * Here we implement safeguards to ensure that a source page
613          * is not copied to its destination page before the data on
614          * the destination page is no longer useful.
615          *
616          * To do this we maintain the invariant that a source page is
617          * either its own destination page, or it is not a
618          * destination page at all.
619          *
620          * That is slightly stronger than required, but the proof
621          * that no problems will not occur is trivial, and the
622          * implementation is simply to verify.
623          *
624          * When allocating all pages normally this algorithm will run
625          * in O(N) time, but in the worst case it will run in O(N^2)
626          * time.   If the runtime is a problem the data structures can
627          * be fixed.
628          */
629         struct page *page;
630         unsigned long addr;
631 
632         /*
633          * Walk through the list of destination pages, and see if I
634          * have a match.
635          */
636         list_for_each_entry(page, &image->dest_pages, lru) {
637                 addr = page_to_pfn(page) << PAGE_SHIFT;
638                 if (addr == destination) {
639                         list_del(&page->lru);
640                         return page;
641                 }
642         }
643         page = NULL;
644         while (1) {
645                 kimage_entry_t *old;
646 
647                 /* Allocate a page, if we run out of memory give up */
648                 page = kimage_alloc_pages(gfp_mask, 0);
649                 if (!page)
650                         return NULL;
651                 /* If the page cannot be used file it away */
652                 if (page_to_pfn(page) >
653                                 (KEXEC_SOURCE_MEMORY_LIMIT >> PAGE_SHIFT)) {
654                         list_add(&page->lru, &image->unusable_pages);
655                         continue;
656                 }
657                 addr = page_to_pfn(page) << PAGE_SHIFT;
658 
659                 /* If it is the destination page we want use it */
660                 if (addr == destination)
661                         break;
662 
663                 /* If the page is not a destination page use it */
664                 if (!kimage_is_destination_range(image, addr,
665                                                   addr + PAGE_SIZE))
666                         break;
667 
668                 /*
669                  * I know that the page is someones destination page.
670                  * See if there is already a source page for this
671                  * destination page.  And if so swap the source pages.
672                  */
673                 old = kimage_dst_used(image, addr);
674                 if (old) {
675                         /* If so move it */
676                         unsigned long old_addr;
677                         struct page *old_page;
678 
679                         old_addr = *old & PAGE_MASK;
680                         old_page = pfn_to_page(old_addr >> PAGE_SHIFT);
681                         copy_highpage(page, old_page);
682                         *old = addr | (*old & ~PAGE_MASK);
683 
684                         /* The old page I have found cannot be a
685                          * destination page, so return it if it's
686                          * gfp_flags honor the ones passed in.
687                          */
688                         if (!(gfp_mask & __GFP_HIGHMEM) &&
689                             PageHighMem(old_page)) {
690                                 kimage_free_pages(old_page);
691                                 continue;
692                         }
693                         addr = old_addr;
694                         page = old_page;
695                         break;
696                 }
697                 /* Place the page on the destination list, to be used later */
698                 list_add(&page->lru, &image->dest_pages);
699         }
700 
701         return page;
702 }
703 
704 static int kimage_load_normal_segment(struct kimage *image,
705                                          struct kexec_segment *segment)
706 {
707         unsigned long maddr;
708         size_t ubytes, mbytes;
709         int result;
710         unsigned char __user *buf = NULL;
711         unsigned char *kbuf = NULL;
712 
713         result = 0;
714         if (image->file_mode)
715                 kbuf = segment->kbuf;
716         else
717                 buf = segment->buf;
718         ubytes = segment->bufsz;
719         mbytes = segment->memsz;
720         maddr = segment->mem;
721 
722         result = kimage_set_destination(image, maddr);
723         if (result < 0)
724                 goto out;
725 
726         while (mbytes) {
727                 struct page *page;
728                 char *ptr;
729                 size_t uchunk, mchunk;
730 
731                 page = kimage_alloc_page(image, GFP_HIGHUSER, maddr);
732                 if (!page) {
733                         result  = -ENOMEM;
734                         goto out;
735                 }
736                 result = kimage_add_page(image, page_to_pfn(page)
737                                                                 << PAGE_SHIFT);
738                 if (result < 0)
739                         goto out;
740 
741                 ptr = kmap(page);
742                 /* Start with a clear page */
743                 clear_page(ptr);
744                 ptr += maddr & ~PAGE_MASK;
745                 mchunk = min_t(size_t, mbytes,
746                                 PAGE_SIZE - (maddr & ~PAGE_MASK));
747                 uchunk = min(ubytes, mchunk);
748 
749                 /* For file based kexec, source pages are in kernel memory */
750                 if (image->file_mode)
751                         memcpy(ptr, kbuf, uchunk);
752                 else
753                         result = copy_from_user(ptr, buf, uchunk);
754                 kunmap(page);
755                 if (result) {
756                         result = -EFAULT;
757                         goto out;
758                 }
759                 ubytes -= uchunk;
760                 maddr  += mchunk;
761                 if (image->file_mode)
762                         kbuf += mchunk;
763                 else
764                         buf += mchunk;
765                 mbytes -= mchunk;
766         }
767 out:
768         return result;
769 }
770 
771 static int kimage_load_crash_segment(struct kimage *image,
772                                         struct kexec_segment *segment)
773 {
774         /* For crash dumps kernels we simply copy the data from
775          * user space to it's destination.
776          * We do things a page at a time for the sake of kmap.
777          */
778         unsigned long maddr;
779         size_t ubytes, mbytes;
780         int result;
781         unsigned char __user *buf = NULL;
782         unsigned char *kbuf = NULL;
783 
784         result = 0;
785         if (image->file_mode)
786                 kbuf = segment->kbuf;
787         else
788                 buf = segment->buf;
789         ubytes = segment->bufsz;
790         mbytes = segment->memsz;
791         maddr = segment->mem;
792         while (mbytes) {
793                 struct page *page;
794                 char *ptr;
795                 size_t uchunk, mchunk;
796 
797                 page = pfn_to_page(maddr >> PAGE_SHIFT);
798                 if (!page) {
799                         result  = -ENOMEM;
800                         goto out;
801                 }
802                 ptr = kmap(page);
803                 ptr += maddr & ~PAGE_MASK;
804                 mchunk = min_t(size_t, mbytes,
805                                 PAGE_SIZE - (maddr & ~PAGE_MASK));
806                 uchunk = min(ubytes, mchunk);
807                 if (mchunk > uchunk) {
808                         /* Zero the trailing part of the page */
809                         memset(ptr + uchunk, 0, mchunk - uchunk);
810                 }
811 
812                 /* For file based kexec, source pages are in kernel memory */
813                 if (image->file_mode)
814                         memcpy(ptr, kbuf, uchunk);
815                 else
816                         result = copy_from_user(ptr, buf, uchunk);
817                 kexec_flush_icache_page(page);
818                 kunmap(page);
819                 if (result) {
820                         result = -EFAULT;
821                         goto out;
822                 }
823                 ubytes -= uchunk;
824                 maddr  += mchunk;
825                 if (image->file_mode)
826                         kbuf += mchunk;
827                 else
828                         buf += mchunk;
829                 mbytes -= mchunk;
830         }
831 out:
832         return result;
833 }
834 
835 int kimage_load_segment(struct kimage *image,
836                                 struct kexec_segment *segment)
837 {
838         int result = -ENOMEM;
839 
840         switch (image->type) {
841         case KEXEC_TYPE_DEFAULT:
842                 result = kimage_load_normal_segment(image, segment);
843                 break;
844         case KEXEC_TYPE_CRASH:
845                 result = kimage_load_crash_segment(image, segment);
846                 break;
847         }
848 
849         return result;
850 }
851 
852 struct kimage *kexec_image;
853 struct kimage *kexec_crash_image;
854 int kexec_load_disabled;
855 
856 void crash_kexec(struct pt_regs *regs)
857 {
858         /* Take the kexec_mutex here to prevent sys_kexec_load
859          * running on one cpu from replacing the crash kernel
860          * we are using after a panic on a different cpu.
861          *
862          * If the crash kernel was not located in a fixed area
863          * of memory the xchg(&kexec_crash_image) would be
864          * sufficient.  But since I reuse the memory...
865          */
866         if (mutex_trylock(&kexec_mutex)) {
867                 if (kexec_crash_image) {
868                         struct pt_regs fixed_regs;
869 
870                         crash_setup_regs(&fixed_regs, regs);
871                         crash_save_vmcoreinfo();
872                         machine_crash_shutdown(&fixed_regs);
873                         machine_kexec(kexec_crash_image);
874                 }
875                 mutex_unlock(&kexec_mutex);
876         }
877 }
878 
879 size_t crash_get_memory_size(void)
880 {
881         size_t size = 0;
882 
883         mutex_lock(&kexec_mutex);
884         if (crashk_res.end != crashk_res.start)
885                 size = resource_size(&crashk_res);
886         mutex_unlock(&kexec_mutex);
887         return size;
888 }
889 
890 void __weak crash_free_reserved_phys_range(unsigned long begin,
891                                            unsigned long end)
892 {
893         unsigned long addr;
894 
895         for (addr = begin; addr < end; addr += PAGE_SIZE)
896                 free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));
897 }
898 
899 int crash_shrink_memory(unsigned long new_size)
900 {
901         int ret = 0;
902         unsigned long start, end;
903         unsigned long old_size;
904         struct resource *ram_res;
905 
906         mutex_lock(&kexec_mutex);
907 
908         if (kexec_crash_image) {
909                 ret = -ENOENT;
910                 goto unlock;
911         }
912         start = crashk_res.start;
913         end = crashk_res.end;
914         old_size = (end == 0) ? 0 : end - start + 1;
915         if (new_size >= old_size) {
916                 ret = (new_size == old_size) ? 0 : -EINVAL;
917                 goto unlock;
918         }
919 
920         ram_res = kzalloc(sizeof(*ram_res), GFP_KERNEL);
921         if (!ram_res) {
922                 ret = -ENOMEM;
923                 goto unlock;
924         }
925 
926         start = roundup(start, KEXEC_CRASH_MEM_ALIGN);
927         end = roundup(start + new_size, KEXEC_CRASH_MEM_ALIGN);
928 
929         crash_map_reserved_pages();
930         crash_free_reserved_phys_range(end, crashk_res.end);
931 
932         if ((start == end) && (crashk_res.parent != NULL))
933                 release_resource(&crashk_res);
934 
935         ram_res->start = end;
936         ram_res->end = crashk_res.end;
937         ram_res->flags = IORESOURCE_BUSY | IORESOURCE_MEM;
938         ram_res->name = "System RAM";
939 
940         crashk_res.end = end - 1;
941 
942         insert_resource(&iomem_resource, ram_res);
943         crash_unmap_reserved_pages();
944 
945 unlock:
946         mutex_unlock(&kexec_mutex);
947         return ret;
948 }
949 
950 static u32 *append_elf_note(u32 *buf, char *name, unsigned type, void *data,
951                             size_t data_len)
952 {
953         struct elf_note note;
954 
955         note.n_namesz = strlen(name) + 1;
956         note.n_descsz = data_len;
957         note.n_type   = type;
958         memcpy(buf, &note, sizeof(note));
959         buf += (sizeof(note) + 3)/4;
960         memcpy(buf, name, note.n_namesz);
961         buf += (note.n_namesz + 3)/4;
962         memcpy(buf, data, note.n_descsz);
963         buf += (note.n_descsz + 3)/4;
964 
965         return buf;
966 }
967 
968 static void final_note(u32 *buf)
969 {
970         struct elf_note note;
971 
972         note.n_namesz = 0;
973         note.n_descsz = 0;
974         note.n_type   = 0;
975         memcpy(buf, &note, sizeof(note));
976 }
977 
978 void crash_save_cpu(struct pt_regs *regs, int cpu)
979 {
980         struct elf_prstatus prstatus;
981         u32 *buf;
982 
983         if ((cpu < 0) || (cpu >= nr_cpu_ids))
984                 return;
985 
986         /* Using ELF notes here is opportunistic.
987          * I need a well defined structure format
988          * for the data I pass, and I need tags
989          * on the data to indicate what information I have
990          * squirrelled away.  ELF notes happen to provide
991          * all of that, so there is no need to invent something new.
992          */
993         buf = (u32 *)per_cpu_ptr(crash_notes, cpu);
994         if (!buf)
995                 return;
996         memset(&prstatus, 0, sizeof(prstatus));
997         prstatus.pr_pid = current->pid;
998         elf_core_copy_kernel_regs(&prstatus.pr_reg, regs);
999         buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS,
1000                               &prstatus, sizeof(prstatus));
1001         final_note(buf);
1002 }
1003 
1004 static int __init crash_notes_memory_init(void)
1005 {
1006         /* Allocate memory for saving cpu registers. */
1007         size_t size, align;
1008 
1009         /*
1010          * crash_notes could be allocated across 2 vmalloc pages when percpu
1011          * is vmalloc based . vmalloc doesn't guarantee 2 continuous vmalloc
1012          * pages are also on 2 continuous physical pages. In this case the
1013          * 2nd part of crash_notes in 2nd page could be lost since only the
1014          * starting address and size of crash_notes are exported through sysfs.
1015          * Here round up the size of crash_notes to the nearest power of two
1016          * and pass it to __alloc_percpu as align value. This can make sure
1017          * crash_notes is allocated inside one physical page.
1018          */
1019         size = sizeof(note_buf_t);
1020         align = min(roundup_pow_of_two(sizeof(note_buf_t)), PAGE_SIZE);
1021 
1022         /*
1023          * Break compile if size is bigger than PAGE_SIZE since crash_notes
1024          * definitely will be in 2 pages with that.
1025          */
1026         BUILD_BUG_ON(size > PAGE_SIZE);
1027 
1028         crash_notes = __alloc_percpu(size, align);
1029         if (!crash_notes) {
1030                 pr_warn("Kexec: Memory allocation for saving cpu register states failed\n");
1031                 return -ENOMEM;
1032         }
1033         return 0;
1034 }
1035 subsys_initcall(crash_notes_memory_init);
1036 
1037 
1038 /*
1039  * parsing the "crashkernel" commandline
1040  *
1041  * this code is intended to be called from architecture specific code
1042  */
1043 
1044 
1045 /*
1046  * This function parses command lines in the format
1047  *
1048  *   crashkernel=ramsize-range:size[,...][@offset]
1049  *
1050  * The function returns 0 on success and -EINVAL on failure.
1051  */
1052 static int __init parse_crashkernel_mem(char *cmdline,
1053                                         unsigned long long system_ram,
1054                                         unsigned long long *crash_size,
1055                                         unsigned long long *crash_base)
1056 {
1057         char *cur = cmdline, *tmp;
1058 
1059         /* for each entry of the comma-separated list */
1060         do {
1061                 unsigned long long start, end = ULLONG_MAX, size;
1062 
1063                 /* get the start of the range */
1064                 start = memparse(cur, &tmp);
1065                 if (cur == tmp) {
1066                         pr_warn("crashkernel: Memory value expected\n");
1067                         return -EINVAL;
1068                 }
1069                 cur = tmp;
1070                 if (*cur != '-') {
1071                         pr_warn("crashkernel: '-' expected\n");
1072                         return -EINVAL;
1073                 }
1074                 cur++;
1075 
1076                 /* if no ':' is here, than we read the end */
1077                 if (*cur != ':') {
1078                         end = memparse(cur, &tmp);
1079                         if (cur == tmp) {
1080                                 pr_warn("crashkernel: Memory value expected\n");
1081                                 return -EINVAL;
1082                         }
1083                         cur = tmp;
1084                         if (end <= start) {
1085                                 pr_warn("crashkernel: end <= start\n");
1086                                 return -EINVAL;
1087                         }
1088                 }
1089 
1090                 if (*cur != ':') {
1091                         pr_warn("crashkernel: ':' expected\n");
1092                         return -EINVAL;
1093                 }
1094                 cur++;
1095 
1096                 size = memparse(cur, &tmp);
1097                 if (cur == tmp) {
1098                         pr_warn("Memory value expected\n");
1099                         return -EINVAL;
1100                 }
1101                 cur = tmp;
1102                 if (size >= system_ram) {
1103                         pr_warn("crashkernel: invalid size\n");
1104                         return -EINVAL;
1105                 }
1106 
1107                 /* match ? */
1108                 if (system_ram >= start && system_ram < end) {
1109                         *crash_size = size;
1110                         break;
1111                 }
1112         } while (*cur++ == ',');
1113 
1114         if (*crash_size > 0) {
1115                 while (*cur && *cur != ' ' && *cur != '@')
1116                         cur++;
1117                 if (*cur == '@') {
1118                         cur++;
1119                         *crash_base = memparse(cur, &tmp);
1120                         if (cur == tmp) {
1121                                 pr_warn("Memory value expected after '@'\n");
1122                                 return -EINVAL;
1123                         }
1124                 }
1125         }
1126 
1127         return 0;
1128 }
1129 
1130 /*
1131  * That function parses "simple" (old) crashkernel command lines like
1132  *
1133  *      crashkernel=size[@offset]
1134  *
1135  * It returns 0 on success and -EINVAL on failure.
1136  */
1137 static int __init parse_crashkernel_simple(char *cmdline,
1138                                            unsigned long long *crash_size,
1139                                            unsigned long long *crash_base)
1140 {
1141         char *cur = cmdline;
1142 
1143         *crash_size = memparse(cmdline, &cur);
1144         if (cmdline == cur) {
1145                 pr_warn("crashkernel: memory value expected\n");
1146                 return -EINVAL;
1147         }
1148 
1149         if (*cur == '@')
1150                 *crash_base = memparse(cur+1, &cur);
1151         else if (*cur != ' ' && *cur != '\0') {
1152                 pr_warn("crashkernel: unrecognized char\n");
1153                 return -EINVAL;
1154         }
1155 
1156         return 0;
1157 }
1158 
1159 #define SUFFIX_HIGH 0
1160 #define SUFFIX_LOW  1
1161 #define SUFFIX_NULL 2
1162 static __initdata char *suffix_tbl[] = {
1163         [SUFFIX_HIGH] = ",high",
1164         [SUFFIX_LOW]  = ",low",
1165         [SUFFIX_NULL] = NULL,
1166 };
1167 
1168 /*
1169  * That function parses "suffix"  crashkernel command lines like
1170  *
1171  *      crashkernel=size,[high|low]
1172  *
1173  * It returns 0 on success and -EINVAL on failure.
1174  */
1175 static int __init parse_crashkernel_suffix(char *cmdline,
1176                                            unsigned long long   *crash_size,
1177                                            const char *suffix)
1178 {
1179         char *cur = cmdline;
1180 
1181         *crash_size = memparse(cmdline, &cur);
1182         if (cmdline == cur) {
1183                 pr_warn("crashkernel: memory value expected\n");
1184                 return -EINVAL;
1185         }
1186 
1187         /* check with suffix */
1188         if (strncmp(cur, suffix, strlen(suffix))) {
1189                 pr_warn("crashkernel: unrecognized char\n");
1190                 return -EINVAL;
1191         }
1192         cur += strlen(suffix);
1193         if (*cur != ' ' && *cur != '\0') {
1194                 pr_warn("crashkernel: unrecognized char\n");
1195                 return -EINVAL;
1196         }
1197 
1198         return 0;
1199 }
1200 
1201 static __init char *get_last_crashkernel(char *cmdline,
1202                              const char *name,
1203                              const char *suffix)
1204 {
1205         char *p = cmdline, *ck_cmdline = NULL;
1206 
1207         /* find crashkernel and use the last one if there are more */
1208         p = strstr(p, name);
1209         while (p) {
1210                 char *end_p = strchr(p, ' ');
1211                 char *q;
1212 
1213                 if (!end_p)
1214                         end_p = p + strlen(p);
1215 
1216                 if (!suffix) {
1217                         int i;
1218 
1219                         /* skip the one with any known suffix */
1220                         for (i = 0; suffix_tbl[i]; i++) {
1221                                 q = end_p - strlen(suffix_tbl[i]);
1222                                 if (!strncmp(q, suffix_tbl[i],
1223                                              strlen(suffix_tbl[i])))
1224                                         goto next;
1225                         }
1226                         ck_cmdline = p;
1227                 } else {
1228                         q = end_p - strlen(suffix);
1229                         if (!strncmp(q, suffix, strlen(suffix)))
1230                                 ck_cmdline = p;
1231                 }
1232 next:
1233                 p = strstr(p+1, name);
1234         }
1235 
1236         if (!ck_cmdline)
1237                 return NULL;
1238 
1239         return ck_cmdline;
1240 }
1241 
1242 static int __init __parse_crashkernel(char *cmdline,
1243                              unsigned long long system_ram,
1244                              unsigned long long *crash_size,
1245                              unsigned long long *crash_base,
1246                              const char *name,
1247                              const char *suffix)
1248 {
1249         char    *first_colon, *first_space;
1250         char    *ck_cmdline;
1251 
1252         BUG_ON(!crash_size || !crash_base);
1253         *crash_size = 0;
1254         *crash_base = 0;
1255 
1256         ck_cmdline = get_last_crashkernel(cmdline, name, suffix);
1257 
1258         if (!ck_cmdline)
1259                 return -EINVAL;
1260 
1261         ck_cmdline += strlen(name);
1262 
1263         if (suffix)
1264                 return parse_crashkernel_suffix(ck_cmdline, crash_size,
1265                                 suffix);
1266         /*
1267          * if the commandline contains a ':', then that's the extended
1268          * syntax -- if not, it must be the classic syntax
1269          */
1270         first_colon = strchr(ck_cmdline, ':');
1271         first_space = strchr(ck_cmdline, ' ');
1272         if (first_colon && (!first_space || first_colon < first_space))
1273                 return parse_crashkernel_mem(ck_cmdline, system_ram,
1274                                 crash_size, crash_base);
1275 
1276         return parse_crashkernel_simple(ck_cmdline, crash_size, crash_base);
1277 }
1278 
1279 /*
1280  * That function is the entry point for command line parsing and should be
1281  * called from the arch-specific code.
1282  */
1283 int __init parse_crashkernel(char *cmdline,
1284                              unsigned long long system_ram,
1285                              unsigned long long *crash_size,
1286                              unsigned long long *crash_base)
1287 {
1288         return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
1289                                         "crashkernel=", NULL);
1290 }
1291 
1292 int __init parse_crashkernel_high(char *cmdline,
1293                              unsigned long long system_ram,
1294                              unsigned long long *crash_size,
1295                              unsigned long long *crash_base)
1296 {
1297         return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
1298                                 "crashkernel=", suffix_tbl[SUFFIX_HIGH]);
1299 }
1300 
1301 int __init parse_crashkernel_low(char *cmdline,
1302                              unsigned long long system_ram,
1303                              unsigned long long *crash_size,
1304                              unsigned long long *crash_base)
1305 {
1306         return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
1307                                 "crashkernel=", suffix_tbl[SUFFIX_LOW]);
1308 }
1309 
1310 static void update_vmcoreinfo_note(void)
1311 {
1312         u32 *buf = vmcoreinfo_note;
1313 
1314         if (!vmcoreinfo_size)
1315                 return;
1316         buf = append_elf_note(buf, VMCOREINFO_NOTE_NAME, 0, vmcoreinfo_data,
1317                               vmcoreinfo_size);
1318         final_note(buf);
1319 }
1320 
1321 void crash_save_vmcoreinfo(void)
1322 {
1323         vmcoreinfo_append_str("CRASHTIME=%ld\n", get_seconds());
1324         update_vmcoreinfo_note();
1325 }
1326 
1327 void vmcoreinfo_append_str(const char *fmt, ...)
1328 {
1329         va_list args;
1330         char buf[0x50];
1331         size_t r;
1332 
1333         va_start(args, fmt);
1334         r = vscnprintf(buf, sizeof(buf), fmt, args);
1335         va_end(args);
1336 
1337         r = min(r, vmcoreinfo_max_size - vmcoreinfo_size);
1338 
1339         memcpy(&vmcoreinfo_data[vmcoreinfo_size], buf, r);
1340 
1341         vmcoreinfo_size += r;
1342 }
1343 
1344 /*
1345  * provide an empty default implementation here -- architecture
1346  * code may override this
1347  */
1348 void __weak arch_crash_save_vmcoreinfo(void)
1349 {}
1350 
1351 unsigned long __weak paddr_vmcoreinfo_note(void)
1352 {
1353         return __pa((unsigned long)(char *)&vmcoreinfo_note);
1354 }
1355 
1356 static int __init crash_save_vmcoreinfo_init(void)
1357 {
1358         VMCOREINFO_OSRELEASE(init_uts_ns.name.release);
1359         VMCOREINFO_PAGESIZE(PAGE_SIZE);
1360 
1361         VMCOREINFO_SYMBOL(init_uts_ns);
1362         VMCOREINFO_SYMBOL(node_online_map);
1363 #ifdef CONFIG_MMU
1364         VMCOREINFO_SYMBOL(swapper_pg_dir);
1365 #endif
1366         VMCOREINFO_SYMBOL(_stext);
1367         VMCOREINFO_SYMBOL(vmap_area_list);
1368 
1369 #ifndef CONFIG_NEED_MULTIPLE_NODES
1370         VMCOREINFO_SYMBOL(mem_map);
1371         VMCOREINFO_SYMBOL(contig_page_data);
1372 #endif
1373 #ifdef CONFIG_SPARSEMEM
1374         VMCOREINFO_SYMBOL(mem_section);
1375         VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS);
1376         VMCOREINFO_STRUCT_SIZE(mem_section);
1377         VMCOREINFO_OFFSET(mem_section, section_mem_map);
1378 #endif
1379         VMCOREINFO_STRUCT_SIZE(page);
1380         VMCOREINFO_STRUCT_SIZE(pglist_data);
1381         VMCOREINFO_STRUCT_SIZE(zone);
1382         VMCOREINFO_STRUCT_SIZE(free_area);
1383         VMCOREINFO_STRUCT_SIZE(list_head);
1384         VMCOREINFO_SIZE(nodemask_t);
1385         VMCOREINFO_OFFSET(page, flags);
1386         VMCOREINFO_OFFSET(page, _count);
1387         VMCOREINFO_OFFSET(page, mapping);
1388         VMCOREINFO_OFFSET(page, lru);
1389         VMCOREINFO_OFFSET(page, _mapcount);
1390         VMCOREINFO_OFFSET(page, private);
1391         VMCOREINFO_OFFSET(pglist_data, node_zones);
1392         VMCOREINFO_OFFSET(pglist_data, nr_zones);
1393 #ifdef CONFIG_FLAT_NODE_MEM_MAP
1394         VMCOREINFO_OFFSET(pglist_data, node_mem_map);
1395 #endif
1396         VMCOREINFO_OFFSET(pglist_data, node_start_pfn);
1397         VMCOREINFO_OFFSET(pglist_data, node_spanned_pages);
1398         VMCOREINFO_OFFSET(pglist_data, node_id);
1399         VMCOREINFO_OFFSET(zone, free_area);
1400         VMCOREINFO_OFFSET(zone, vm_stat);
1401         VMCOREINFO_OFFSET(zone, spanned_pages);
1402         VMCOREINFO_OFFSET(free_area, free_list);
1403         VMCOREINFO_OFFSET(list_head, next);
1404         VMCOREINFO_OFFSET(list_head, prev);
1405         VMCOREINFO_OFFSET(vmap_area, va_start);
1406         VMCOREINFO_OFFSET(vmap_area, list);
1407         VMCOREINFO_LENGTH(zone.free_area, MAX_ORDER);
1408         log_buf_kexec_setup();
1409         VMCOREINFO_LENGTH(free_area.free_list, MIGRATE_TYPES);
1410         VMCOREINFO_NUMBER(NR_FREE_PAGES);
1411         VMCOREINFO_NUMBER(PG_lru);
1412         VMCOREINFO_NUMBER(PG_private);
1413         VMCOREINFO_NUMBER(PG_swapcache);
1414         VMCOREINFO_NUMBER(PG_slab);
1415 #ifdef CONFIG_MEMORY_FAILURE
1416         VMCOREINFO_NUMBER(PG_hwpoison);
1417 #endif
1418         VMCOREINFO_NUMBER(PG_head_mask);
1419         VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE);
1420 #ifdef CONFIG_X86
1421         VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE);
1422 #endif
1423 #ifdef CONFIG_HUGETLBFS
1424         VMCOREINFO_SYMBOL(free_huge_page);
1425 #endif
1426 
1427         arch_crash_save_vmcoreinfo();
1428         update_vmcoreinfo_note();
1429 
1430         return 0;
1431 }
1432 
1433 subsys_initcall(crash_save_vmcoreinfo_init);
1434 
1435 /*
1436  * Move into place and start executing a preloaded standalone
1437  * executable.  If nothing was preloaded return an error.
1438  */
1439 int kernel_kexec(void)
1440 {
1441         int error = 0;
1442 
1443         if (!mutex_trylock(&kexec_mutex))
1444                 return -EBUSY;
1445         if (!kexec_image) {
1446                 error = -EINVAL;
1447                 goto Unlock;
1448         }
1449 
1450 #ifdef CONFIG_KEXEC_JUMP
1451         if (kexec_image->preserve_context) {
1452                 lock_system_sleep();
1453                 pm_prepare_console();
1454                 error = freeze_processes();
1455                 if (error) {
1456                         error = -EBUSY;
1457                         goto Restore_console;
1458                 }
1459                 suspend_console();
1460                 error = dpm_suspend_start(PMSG_FREEZE);
1461                 if (error)
1462                         goto Resume_console;
1463                 /* At this point, dpm_suspend_start() has been called,
1464                  * but *not* dpm_suspend_end(). We *must* call
1465                  * dpm_suspend_end() now.  Otherwise, drivers for
1466                  * some devices (e.g. interrupt controllers) become
1467                  * desynchronized with the actual state of the
1468                  * hardware at resume time, and evil weirdness ensues.
1469                  */
1470                 error = dpm_suspend_end(PMSG_FREEZE);
1471                 if (error)
1472                         goto Resume_devices;
1473                 error = disable_nonboot_cpus();
1474                 if (error)
1475                         goto Enable_cpus;
1476                 local_irq_disable();
1477                 error = syscore_suspend();
1478                 if (error)
1479                         goto Enable_irqs;
1480         } else
1481 #endif
1482         {
1483                 kexec_in_progress = true;
1484                 kernel_restart_prepare(NULL);
1485                 migrate_to_reboot_cpu();
1486 
1487                 /*
1488                  * migrate_to_reboot_cpu() disables CPU hotplug assuming that
1489                  * no further code needs to use CPU hotplug (which is true in
1490                  * the reboot case). However, the kexec path depends on using
1491                  * CPU hotplug again; so re-enable it here.
1492                  */
1493                 cpu_hotplug_enable();
1494                 pr_emerg("Starting new kernel\n");
1495                 machine_shutdown();
1496         }
1497 
1498         machine_kexec(kexec_image);
1499 
1500 #ifdef CONFIG_KEXEC_JUMP
1501         if (kexec_image->preserve_context) {
1502                 syscore_resume();
1503  Enable_irqs:
1504                 local_irq_enable();
1505  Enable_cpus:
1506                 enable_nonboot_cpus();
1507                 dpm_resume_start(PMSG_RESTORE);
1508  Resume_devices:
1509                 dpm_resume_end(PMSG_RESTORE);
1510  Resume_console:
1511                 resume_console();
1512                 thaw_processes();
1513  Restore_console:
1514                 pm_restore_console();
1515                 unlock_system_sleep();
1516         }
1517 #endif
1518 
1519  Unlock:
1520         mutex_unlock(&kexec_mutex);
1521         return error;
1522 }
1523 
1524 /*
1525  * Add and remove page tables for crashkernel memory
1526  *
1527  * Provide an empty default implementation here -- architecture
1528  * code may override this
1529  */
1530 void __weak crash_map_reserved_pages(void)
1531 {}
1532 
1533 void __weak crash_unmap_reserved_pages(void)
1534 {}
1535 

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