2 * kexec.c - kexec system call
3 * Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com>
5 * This source code is licensed under the GNU General Public License,
6 * Version 2. See the file COPYING for more details.
9 #include <linux/capability.h>
11 #include <linux/file.h>
12 #include <linux/slab.h>
14 #include <linux/kexec.h>
15 #include <linux/spinlock.h>
16 #include <linux/list.h>
17 #include <linux/highmem.h>
18 #include <linux/syscalls.h>
19 #include <linux/reboot.h>
20 #include <linux/syscalls.h>
21 #include <linux/ioport.h>
22 #include <linux/hardirq.h>
23 #include <linux/elf.h>
24 #include <linux/elfcore.h>
27 #include <asm/uaccess.h>
29 #include <asm/system.h>
30 #include <asm/semaphore.h>
32 /* Per cpu memory for storing cpu states in case of system crash. */
33 note_buf_t* crash_notes;
35 /* Location of the reserved area for the crash kernel */
36 struct resource crashk_res = {
37 .name = "Crash kernel",
40 .flags = IORESOURCE_BUSY | IORESOURCE_MEM
43 int kexec_should_crash(struct task_struct *p)
45 if (in_interrupt() || !p->pid || is_init(p) || panic_on_oops)
51 * When kexec transitions to the new kernel there is a one-to-one
52 * mapping between physical and virtual addresses. On processors
53 * where you can disable the MMU this is trivial, and easy. For
54 * others it is still a simple predictable page table to setup.
56 * In that environment kexec copies the new kernel to its final
57 * resting place. This means I can only support memory whose
58 * physical address can fit in an unsigned long. In particular
59 * addresses where (pfn << PAGE_SHIFT) > ULONG_MAX cannot be handled.
60 * If the assembly stub has more restrictive requirements
61 * KEXEC_SOURCE_MEMORY_LIMIT and KEXEC_DEST_MEMORY_LIMIT can be
62 * defined more restrictively in <asm/kexec.h>.
64 * The code for the transition from the current kernel to the
65 * the new kernel is placed in the control_code_buffer, whose size
66 * is given by KEXEC_CONTROL_CODE_SIZE. In the best case only a single
67 * page of memory is necessary, but some architectures require more.
68 * Because this memory must be identity mapped in the transition from
69 * virtual to physical addresses it must live in the range
70 * 0 - TASK_SIZE, as only the user space mappings are arbitrarily
73 * The assembly stub in the control code buffer is passed a linked list
74 * of descriptor pages detailing the source pages of the new kernel,
75 * and the destination addresses of those source pages. As this data
76 * structure is not used in the context of the current OS, it must
79 * The code has been made to work with highmem pages and will use a
80 * destination page in its final resting place (if it happens
81 * to allocate it). The end product of this is that most of the
82 * physical address space, and most of RAM can be used.
84 * Future directions include:
85 * - allocating a page table with the control code buffer identity
86 * mapped, to simplify machine_kexec and make kexec_on_panic more
91 * KIMAGE_NO_DEST is an impossible destination address..., for
92 * allocating pages whose destination address we do not care about.
94 #define KIMAGE_NO_DEST (-1UL)
96 static int kimage_is_destination_range(struct kimage *image,
97 unsigned long start, unsigned long end);
98 static struct page *kimage_alloc_page(struct kimage *image,
102 static int do_kimage_alloc(struct kimage **rimage, unsigned long entry,
103 unsigned long nr_segments,
104 struct kexec_segment __user *segments)
106 size_t segment_bytes;
107 struct kimage *image;
111 /* Allocate a controlling structure */
113 image = kzalloc(sizeof(*image), GFP_KERNEL);
118 image->entry = &image->head;
119 image->last_entry = &image->head;
120 image->control_page = ~0; /* By default this does not apply */
121 image->start = entry;
122 image->type = KEXEC_TYPE_DEFAULT;
124 /* Initialize the list of control pages */
125 INIT_LIST_HEAD(&image->control_pages);
127 /* Initialize the list of destination pages */
128 INIT_LIST_HEAD(&image->dest_pages);
130 /* Initialize the list of unuseable pages */
131 INIT_LIST_HEAD(&image->unuseable_pages);
133 /* Read in the segments */
134 image->nr_segments = nr_segments;
135 segment_bytes = nr_segments * sizeof(*segments);
136 result = copy_from_user(image->segment, segments, segment_bytes);
141 * Verify we have good destination addresses. The caller is
142 * responsible for making certain we don't attempt to load
143 * the new image into invalid or reserved areas of RAM. This
144 * just verifies it is an address we can use.
146 * Since the kernel does everything in page size chunks ensure
147 * the destination addreses are page aligned. Too many
148 * special cases crop of when we don't do this. The most
149 * insidious is getting overlapping destination addresses
150 * simply because addresses are changed to page size
153 result = -EADDRNOTAVAIL;
154 for (i = 0; i < nr_segments; i++) {
155 unsigned long mstart, mend;
157 mstart = image->segment[i].mem;
158 mend = mstart + image->segment[i].memsz;
159 if ((mstart & ~PAGE_MASK) || (mend & ~PAGE_MASK))
161 if (mend >= KEXEC_DESTINATION_MEMORY_LIMIT)
165 /* Verify our destination addresses do not overlap.
166 * If we alloed overlapping destination addresses
167 * through very weird things can happen with no
168 * easy explanation as one segment stops on another.
171 for (i = 0; i < nr_segments; i++) {
172 unsigned long mstart, mend;
175 mstart = image->segment[i].mem;
176 mend = mstart + image->segment[i].memsz;
177 for (j = 0; j < i; j++) {
178 unsigned long pstart, pend;
179 pstart = image->segment[j].mem;
180 pend = pstart + image->segment[j].memsz;
181 /* Do the segments overlap ? */
182 if ((mend > pstart) && (mstart < pend))
187 /* Ensure our buffer sizes are strictly less than
188 * our memory sizes. This should always be the case,
189 * and it is easier to check up front than to be surprised
193 for (i = 0; i < nr_segments; i++) {
194 if (image->segment[i].bufsz > image->segment[i].memsz)
209 static int kimage_normal_alloc(struct kimage **rimage, unsigned long entry,
210 unsigned long nr_segments,
211 struct kexec_segment __user *segments)
214 struct kimage *image;
216 /* Allocate and initialize a controlling structure */
218 result = do_kimage_alloc(&image, entry, nr_segments, segments);
225 * Find a location for the control code buffer, and add it
226 * the vector of segments so that it's pages will also be
227 * counted as destination pages.
230 image->control_code_page = kimage_alloc_control_pages(image,
231 get_order(KEXEC_CONTROL_CODE_SIZE));
232 if (!image->control_code_page) {
233 printk(KERN_ERR "Could not allocate control_code_buffer\n");
247 static int kimage_crash_alloc(struct kimage **rimage, unsigned long entry,
248 unsigned long nr_segments,
249 struct kexec_segment __user *segments)
252 struct kimage *image;
256 /* Verify we have a valid entry point */
257 if ((entry < crashk_res.start) || (entry > crashk_res.end)) {
258 result = -EADDRNOTAVAIL;
262 /* Allocate and initialize a controlling structure */
263 result = do_kimage_alloc(&image, entry, nr_segments, segments);
267 /* Enable the special crash kernel control page
270 image->control_page = crashk_res.start;
271 image->type = KEXEC_TYPE_CRASH;
274 * Verify we have good destination addresses. Normally
275 * the caller is responsible for making certain we don't
276 * attempt to load the new image into invalid or reserved
277 * areas of RAM. But crash kernels are preloaded into a
278 * reserved area of ram. We must ensure the addresses
279 * are in the reserved area otherwise preloading the
280 * kernel could corrupt things.
282 result = -EADDRNOTAVAIL;
283 for (i = 0; i < nr_segments; i++) {
284 unsigned long mstart, mend;
286 mstart = image->segment[i].mem;
287 mend = mstart + image->segment[i].memsz - 1;
288 /* Ensure we are within the crash kernel limits */
289 if ((mstart < crashk_res.start) || (mend > crashk_res.end))
294 * Find a location for the control code buffer, and add
295 * the vector of segments so that it's pages will also be
296 * counted as destination pages.
299 image->control_code_page = kimage_alloc_control_pages(image,
300 get_order(KEXEC_CONTROL_CODE_SIZE));
301 if (!image->control_code_page) {
302 printk(KERN_ERR "Could not allocate control_code_buffer\n");
316 static int kimage_is_destination_range(struct kimage *image,
322 for (i = 0; i < image->nr_segments; i++) {
323 unsigned long mstart, mend;
325 mstart = image->segment[i].mem;
326 mend = mstart + image->segment[i].memsz;
327 if ((end > mstart) && (start < mend))
334 static struct page *kimage_alloc_pages(gfp_t gfp_mask, unsigned int order)
338 pages = alloc_pages(gfp_mask, order);
340 unsigned int count, i;
341 pages->mapping = NULL;
342 set_page_private(pages, order);
344 for (i = 0; i < count; i++)
345 SetPageReserved(pages + i);
351 static void kimage_free_pages(struct page *page)
353 unsigned int order, count, i;
355 order = page_private(page);
357 for (i = 0; i < count; i++)
358 ClearPageReserved(page + i);
359 __free_pages(page, order);
362 static void kimage_free_page_list(struct list_head *list)
364 struct list_head *pos, *next;
366 list_for_each_safe(pos, next, list) {
369 page = list_entry(pos, struct page, lru);
370 list_del(&page->lru);
371 kimage_free_pages(page);
375 static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
378 /* Control pages are special, they are the intermediaries
379 * that are needed while we copy the rest of the pages
380 * to their final resting place. As such they must
381 * not conflict with either the destination addresses
382 * or memory the kernel is already using.
384 * The only case where we really need more than one of
385 * these are for architectures where we cannot disable
386 * the MMU and must instead generate an identity mapped
387 * page table for all of the memory.
389 * At worst this runs in O(N) of the image size.
391 struct list_head extra_pages;
396 INIT_LIST_HEAD(&extra_pages);
398 /* Loop while I can allocate a page and the page allocated
399 * is a destination page.
402 unsigned long pfn, epfn, addr, eaddr;
404 pages = kimage_alloc_pages(GFP_KERNEL, order);
407 pfn = page_to_pfn(pages);
409 addr = pfn << PAGE_SHIFT;
410 eaddr = epfn << PAGE_SHIFT;
411 if ((epfn >= (KEXEC_CONTROL_MEMORY_LIMIT >> PAGE_SHIFT)) ||
412 kimage_is_destination_range(image, addr, eaddr)) {
413 list_add(&pages->lru, &extra_pages);
419 /* Remember the allocated page... */
420 list_add(&pages->lru, &image->control_pages);
422 /* Because the page is already in it's destination
423 * location we will never allocate another page at
424 * that address. Therefore kimage_alloc_pages
425 * will not return it (again) and we don't need
426 * to give it an entry in image->segment[].
429 /* Deal with the destination pages I have inadvertently allocated.
431 * Ideally I would convert multi-page allocations into single
432 * page allocations, and add everyting to image->dest_pages.
434 * For now it is simpler to just free the pages.
436 kimage_free_page_list(&extra_pages);
441 static struct page *kimage_alloc_crash_control_pages(struct kimage *image,
444 /* Control pages are special, they are the intermediaries
445 * that are needed while we copy the rest of the pages
446 * to their final resting place. As such they must
447 * not conflict with either the destination addresses
448 * or memory the kernel is already using.
450 * Control pages are also the only pags we must allocate
451 * when loading a crash kernel. All of the other pages
452 * are specified by the segments and we just memcpy
453 * into them directly.
455 * The only case where we really need more than one of
456 * these are for architectures where we cannot disable
457 * the MMU and must instead generate an identity mapped
458 * page table for all of the memory.
460 * Given the low demand this implements a very simple
461 * allocator that finds the first hole of the appropriate
462 * size in the reserved memory region, and allocates all
463 * of the memory up to and including the hole.
465 unsigned long hole_start, hole_end, size;
469 size = (1 << order) << PAGE_SHIFT;
470 hole_start = (image->control_page + (size - 1)) & ~(size - 1);
471 hole_end = hole_start + size - 1;
472 while (hole_end <= crashk_res.end) {
475 if (hole_end > KEXEC_CONTROL_MEMORY_LIMIT)
477 if (hole_end > crashk_res.end)
479 /* See if I overlap any of the segments */
480 for (i = 0; i < image->nr_segments; i++) {
481 unsigned long mstart, mend;
483 mstart = image->segment[i].mem;
484 mend = mstart + image->segment[i].memsz - 1;
485 if ((hole_end >= mstart) && (hole_start <= mend)) {
486 /* Advance the hole to the end of the segment */
487 hole_start = (mend + (size - 1)) & ~(size - 1);
488 hole_end = hole_start + size - 1;
492 /* If I don't overlap any segments I have found my hole! */
493 if (i == image->nr_segments) {
494 pages = pfn_to_page(hole_start >> PAGE_SHIFT);
499 image->control_page = hole_end;
505 struct page *kimage_alloc_control_pages(struct kimage *image,
508 struct page *pages = NULL;
510 switch (image->type) {
511 case KEXEC_TYPE_DEFAULT:
512 pages = kimage_alloc_normal_control_pages(image, order);
514 case KEXEC_TYPE_CRASH:
515 pages = kimage_alloc_crash_control_pages(image, order);
522 static int kimage_add_entry(struct kimage *image, kimage_entry_t entry)
524 if (*image->entry != 0)
527 if (image->entry == image->last_entry) {
528 kimage_entry_t *ind_page;
531 page = kimage_alloc_page(image, GFP_KERNEL, KIMAGE_NO_DEST);
535 ind_page = page_address(page);
536 *image->entry = virt_to_phys(ind_page) | IND_INDIRECTION;
537 image->entry = ind_page;
538 image->last_entry = ind_page +
539 ((PAGE_SIZE/sizeof(kimage_entry_t)) - 1);
541 *image->entry = entry;
548 static int kimage_set_destination(struct kimage *image,
549 unsigned long destination)
553 destination &= PAGE_MASK;
554 result = kimage_add_entry(image, destination | IND_DESTINATION);
556 image->destination = destination;
562 static int kimage_add_page(struct kimage *image, unsigned long page)
567 result = kimage_add_entry(image, page | IND_SOURCE);
569 image->destination += PAGE_SIZE;
575 static void kimage_free_extra_pages(struct kimage *image)
577 /* Walk through and free any extra destination pages I may have */
578 kimage_free_page_list(&image->dest_pages);
580 /* Walk through and free any unuseable pages I have cached */
581 kimage_free_page_list(&image->unuseable_pages);
584 static int kimage_terminate(struct kimage *image)
586 if (*image->entry != 0)
589 *image->entry = IND_DONE;
594 #define for_each_kimage_entry(image, ptr, entry) \
595 for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); \
596 ptr = (entry & IND_INDIRECTION)? \
597 phys_to_virt((entry & PAGE_MASK)): ptr +1)
599 static void kimage_free_entry(kimage_entry_t entry)
603 page = pfn_to_page(entry >> PAGE_SHIFT);
604 kimage_free_pages(page);
607 static void kimage_free(struct kimage *image)
609 kimage_entry_t *ptr, entry;
610 kimage_entry_t ind = 0;
615 kimage_free_extra_pages(image);
616 for_each_kimage_entry(image, ptr, entry) {
617 if (entry & IND_INDIRECTION) {
618 /* Free the previous indirection page */
619 if (ind & IND_INDIRECTION)
620 kimage_free_entry(ind);
621 /* Save this indirection page until we are
626 else if (entry & IND_SOURCE)
627 kimage_free_entry(entry);
629 /* Free the final indirection page */
630 if (ind & IND_INDIRECTION)
631 kimage_free_entry(ind);
633 /* Handle any machine specific cleanup */
634 machine_kexec_cleanup(image);
636 /* Free the kexec control pages... */
637 kimage_free_page_list(&image->control_pages);
641 static kimage_entry_t *kimage_dst_used(struct kimage *image,
644 kimage_entry_t *ptr, entry;
645 unsigned long destination = 0;
647 for_each_kimage_entry(image, ptr, entry) {
648 if (entry & IND_DESTINATION)
649 destination = entry & PAGE_MASK;
650 else if (entry & IND_SOURCE) {
651 if (page == destination)
653 destination += PAGE_SIZE;
660 static struct page *kimage_alloc_page(struct kimage *image,
662 unsigned long destination)
665 * Here we implement safeguards to ensure that a source page
666 * is not copied to its destination page before the data on
667 * the destination page is no longer useful.
669 * To do this we maintain the invariant that a source page is
670 * either its own destination page, or it is not a
671 * destination page at all.
673 * That is slightly stronger than required, but the proof
674 * that no problems will not occur is trivial, and the
675 * implementation is simply to verify.
677 * When allocating all pages normally this algorithm will run
678 * in O(N) time, but in the worst case it will run in O(N^2)
679 * time. If the runtime is a problem the data structures can
686 * Walk through the list of destination pages, and see if I
689 list_for_each_entry(page, &image->dest_pages, lru) {
690 addr = page_to_pfn(page) << PAGE_SHIFT;
691 if (addr == destination) {
692 list_del(&page->lru);
700 /* Allocate a page, if we run out of memory give up */
701 page = kimage_alloc_pages(gfp_mask, 0);
704 /* If the page cannot be used file it away */
705 if (page_to_pfn(page) >
706 (KEXEC_SOURCE_MEMORY_LIMIT >> PAGE_SHIFT)) {
707 list_add(&page->lru, &image->unuseable_pages);
710 addr = page_to_pfn(page) << PAGE_SHIFT;
712 /* If it is the destination page we want use it */
713 if (addr == destination)
716 /* If the page is not a destination page use it */
717 if (!kimage_is_destination_range(image, addr,
722 * I know that the page is someones destination page.
723 * See if there is already a source page for this
724 * destination page. And if so swap the source pages.
726 old = kimage_dst_used(image, addr);
729 unsigned long old_addr;
730 struct page *old_page;
732 old_addr = *old & PAGE_MASK;
733 old_page = pfn_to_page(old_addr >> PAGE_SHIFT);
734 copy_highpage(page, old_page);
735 *old = addr | (*old & ~PAGE_MASK);
737 /* The old page I have found cannot be a
738 * destination page, so return it.
745 /* Place the page on the destination list I
748 list_add(&page->lru, &image->dest_pages);
755 static int kimage_load_normal_segment(struct kimage *image,
756 struct kexec_segment *segment)
759 unsigned long ubytes, mbytes;
761 unsigned char __user *buf;
765 ubytes = segment->bufsz;
766 mbytes = segment->memsz;
767 maddr = segment->mem;
769 result = kimage_set_destination(image, maddr);
776 size_t uchunk, mchunk;
778 page = kimage_alloc_page(image, GFP_HIGHUSER, maddr);
783 result = kimage_add_page(image, page_to_pfn(page)
789 /* Start with a clear page */
790 memset(ptr, 0, PAGE_SIZE);
791 ptr += maddr & ~PAGE_MASK;
792 mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK);
800 result = copy_from_user(ptr, buf, uchunk);
803 result = (result < 0) ? result : -EIO;
815 static int kimage_load_crash_segment(struct kimage *image,
816 struct kexec_segment *segment)
818 /* For crash dumps kernels we simply copy the data from
819 * user space to it's destination.
820 * We do things a page at a time for the sake of kmap.
823 unsigned long ubytes, mbytes;
825 unsigned char __user *buf;
829 ubytes = segment->bufsz;
830 mbytes = segment->memsz;
831 maddr = segment->mem;
835 size_t uchunk, mchunk;
837 page = pfn_to_page(maddr >> PAGE_SHIFT);
843 ptr += maddr & ~PAGE_MASK;
844 mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK);
849 if (uchunk > ubytes) {
851 /* Zero the trailing part of the page */
852 memset(ptr + uchunk, 0, mchunk - uchunk);
854 result = copy_from_user(ptr, buf, uchunk);
855 kexec_flush_icache_page(page);
858 result = (result < 0) ? result : -EIO;
870 static int kimage_load_segment(struct kimage *image,
871 struct kexec_segment *segment)
873 int result = -ENOMEM;
875 switch (image->type) {
876 case KEXEC_TYPE_DEFAULT:
877 result = kimage_load_normal_segment(image, segment);
879 case KEXEC_TYPE_CRASH:
880 result = kimage_load_crash_segment(image, segment);
888 * Exec Kernel system call: for obvious reasons only root may call it.
890 * This call breaks up into three pieces.
891 * - A generic part which loads the new kernel from the current
892 * address space, and very carefully places the data in the
895 * - A generic part that interacts with the kernel and tells all of
896 * the devices to shut down. Preventing on-going dmas, and placing
897 * the devices in a consistent state so a later kernel can
900 * - A machine specific part that includes the syscall number
901 * and the copies the image to it's final destination. And
902 * jumps into the image at entry.
904 * kexec does not sync, or unmount filesystems so if you need
905 * that to happen you need to do that yourself.
907 struct kimage *kexec_image;
908 struct kimage *kexec_crash_image;
910 * A home grown binary mutex.
911 * Nothing can wait so this mutex is safe to use
912 * in interrupt context :)
914 static int kexec_lock;
916 asmlinkage long sys_kexec_load(unsigned long entry, unsigned long nr_segments,
917 struct kexec_segment __user *segments,
920 struct kimage **dest_image, *image;
924 /* We only trust the superuser with rebooting the system. */
925 if (!capable(CAP_SYS_BOOT))
929 * Verify we have a legal set of flags
930 * This leaves us room for future extensions.
932 if ((flags & KEXEC_FLAGS) != (flags & ~KEXEC_ARCH_MASK))
935 /* Verify we are on the appropriate architecture */
936 if (((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH) &&
937 ((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT))
940 /* Put an artificial cap on the number
941 * of segments passed to kexec_load.
943 if (nr_segments > KEXEC_SEGMENT_MAX)
949 /* Because we write directly to the reserved memory
950 * region when loading crash kernels we need a mutex here to
951 * prevent multiple crash kernels from attempting to load
952 * simultaneously, and to prevent a crash kernel from loading
953 * over the top of a in use crash kernel.
955 * KISS: always take the mutex.
957 locked = xchg(&kexec_lock, 1);
961 dest_image = &kexec_image;
962 if (flags & KEXEC_ON_CRASH)
963 dest_image = &kexec_crash_image;
964 if (nr_segments > 0) {
967 /* Loading another kernel to reboot into */
968 if ((flags & KEXEC_ON_CRASH) == 0)
969 result = kimage_normal_alloc(&image, entry,
970 nr_segments, segments);
971 /* Loading another kernel to switch to if this one crashes */
972 else if (flags & KEXEC_ON_CRASH) {
973 /* Free any current crash dump kernel before
976 kimage_free(xchg(&kexec_crash_image, NULL));
977 result = kimage_crash_alloc(&image, entry,
978 nr_segments, segments);
983 result = machine_kexec_prepare(image);
987 for (i = 0; i < nr_segments; i++) {
988 result = kimage_load_segment(image, &image->segment[i]);
992 result = kimage_terminate(image);
996 /* Install the new kernel, and Uninstall the old */
997 image = xchg(dest_image, image);
1000 locked = xchg(&kexec_lock, 0); /* Release the mutex */
1007 #ifdef CONFIG_COMPAT
1008 asmlinkage long compat_sys_kexec_load(unsigned long entry,
1009 unsigned long nr_segments,
1010 struct compat_kexec_segment __user *segments,
1011 unsigned long flags)
1013 struct compat_kexec_segment in;
1014 struct kexec_segment out, __user *ksegments;
1015 unsigned long i, result;
1017 /* Don't allow clients that don't understand the native
1018 * architecture to do anything.
1020 if ((flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_DEFAULT)
1023 if (nr_segments > KEXEC_SEGMENT_MAX)
1026 ksegments = compat_alloc_user_space(nr_segments * sizeof(out));
1027 for (i=0; i < nr_segments; i++) {
1028 result = copy_from_user(&in, &segments[i], sizeof(in));
1032 out.buf = compat_ptr(in.buf);
1033 out.bufsz = in.bufsz;
1035 out.memsz = in.memsz;
1037 result = copy_to_user(&ksegments[i], &out, sizeof(out));
1042 return sys_kexec_load(entry, nr_segments, ksegments, flags);
1046 void crash_kexec(struct pt_regs *regs)
1051 /* Take the kexec_lock here to prevent sys_kexec_load
1052 * running on one cpu from replacing the crash kernel
1053 * we are using after a panic on a different cpu.
1055 * If the crash kernel was not located in a fixed area
1056 * of memory the xchg(&kexec_crash_image) would be
1057 * sufficient. But since I reuse the memory...
1059 locked = xchg(&kexec_lock, 1);
1061 if (kexec_crash_image) {
1062 struct pt_regs fixed_regs;
1063 crash_setup_regs(&fixed_regs, regs);
1064 machine_crash_shutdown(&fixed_regs);
1065 machine_kexec(kexec_crash_image);
1067 locked = xchg(&kexec_lock, 0);
1072 static u32 *append_elf_note(u32 *buf, char *name, unsigned type, void *data,
1075 struct elf_note note;
1077 note.n_namesz = strlen(name) + 1;
1078 note.n_descsz = data_len;
1080 memcpy(buf, ¬e, sizeof(note));
1081 buf += (sizeof(note) + 3)/4;
1082 memcpy(buf, name, note.n_namesz);
1083 buf += (note.n_namesz + 3)/4;
1084 memcpy(buf, data, note.n_descsz);
1085 buf += (note.n_descsz + 3)/4;
1090 static void final_note(u32 *buf)
1092 struct elf_note note;
1097 memcpy(buf, ¬e, sizeof(note));
1100 void crash_save_cpu(struct pt_regs *regs, int cpu)
1102 struct elf_prstatus prstatus;
1105 if ((cpu < 0) || (cpu >= NR_CPUS))
1108 /* Using ELF notes here is opportunistic.
1109 * I need a well defined structure format
1110 * for the data I pass, and I need tags
1111 * on the data to indicate what information I have
1112 * squirrelled away. ELF notes happen to provide
1113 * all of that, so there is no need to invent something new.
1115 buf = (u32*)per_cpu_ptr(crash_notes, cpu);
1118 memset(&prstatus, 0, sizeof(prstatus));
1119 prstatus.pr_pid = current->pid;
1120 elf_core_copy_regs(&prstatus.pr_reg, regs);
1121 buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS,
1122 &prstatus, sizeof(prstatus));
1126 static int __init crash_notes_memory_init(void)
1128 /* Allocate memory for saving cpu registers. */
1129 crash_notes = alloc_percpu(note_buf_t);
1131 printk("Kexec: Memory allocation for saving cpu register"
1132 " states failed\n");
1137 module_init(crash_notes_memory_init)