/*
   * kexec.c - kexec system call
   * Copyright (C) 2002-2004 Eric Biederman  <ebiederm@xmission.com>
   *
   * This source code is licensed under the GNU General Public License,
   * Version 2.  See the file COPYING for more details.
   */

  #define pr_fmt(fmt)	"kexec: " fmt

  #include <linux/capability.h>

  #include <linux/mm.h>
  #include <linux/file.h>
  #include <linux/slab.h>
  #include <linux/fs.h>
  #include <linux/kexec.h>

  #include <linux/mutex.h>

  #include <linux/list.h>
  #include <linux/highmem.h>
  #include <linux/syscalls.h>
  #include <linux/reboot.h>

  #include <linux/ioport.h>

  #include <linux/hardirq.h>

  #include <linux/elf.h>
  #include <linux/elfcore.h>

  #include <linux/utsname.h>
  #include <linux/numa.h>

  #include <linux/suspend.h>
  #include <linux/device.h>

  #include <linux/freezer.h>
  #include <linux/pm.h>
  #include <linux/cpu.h>
  #include <linux/console.h>

  #include <linux/vmalloc.h>

  #include <linux/swap.h>

  #include <linux/syscore_ops.h>

  #include <linux/compiler.h>

  #include <linux/hugetlb.h>

  #include <asm/page.h>
  #include <asm/uaccess.h>
  #include <asm/io.h>

  #include <asm/sections.h>

  #include <crypto/hash.h>
  #include <crypto/sha.h>

  /* Per cpu memory for storing cpu states in case of system crash. */

  note_buf_t __percpu *crash_notes;

  /* vmcoreinfo stuff */

  static unsigned char vmcoreinfo_data[VMCOREINFO_BYTES];

  u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];

  size_t vmcoreinfo_size;
  size_t vmcoreinfo_max_size = sizeof(vmcoreinfo_data);

  /* Flag to indicate we are going to kexec a new kernel */
  bool kexec_in_progress = false;

  /*
   * Declare these symbols weak so that if architecture provides a purgatory,
   * these will be overridden.
   */
  char __weak kexec_purgatory[0];
  size_t __weak kexec_purgatory_size = 0;

  #ifdef CONFIG_KEXEC_FILE

  static int kexec_calculate_store_digests(struct kimage *image);

  #endif

  /* Location of the reserved area for the crash kernel */
  struct resource crashk_res = {
  	.name  = "Crash kernel",
  	.start = 0,
  	.end   = 0,
  	.flags = IORESOURCE_BUSY | IORESOURCE_MEM
  };

  struct resource crashk_low_res = {

  	.name  = "Crash kernel",

  	.start = 0,
  	.end   = 0,
  	.flags = IORESOURCE_BUSY | IORESOURCE_MEM
  };

  int kexec_should_crash(struct task_struct *p)
  {

  	if (in_interrupt() || !p->pid || is_global_init(p) || panic_on_oops)

  		return 1;
  	return 0;
  }

  /*
   * When kexec transitions to the new kernel there is a one-to-one
   * mapping between physical and virtual addresses.  On processors
   * where you can disable the MMU this is trivial, and easy.  For
   * others it is still a simple predictable page table to setup.
   *
   * In that environment kexec copies the new kernel to its final
   * resting place.  This means I can only support memory whose
   * physical address can fit in an unsigned long.  In particular
   * addresses where (pfn << PAGE_SHIFT) > ULONG_MAX cannot be handled.
   * If the assembly stub has more restrictive requirements
   * KEXEC_SOURCE_MEMORY_LIMIT and KEXEC_DEST_MEMORY_LIMIT can be
   * defined more restrictively in <asm/kexec.h>.
   *
   * The code for the transition from the current kernel to the
   * the new kernel is placed in the control_code_buffer, whose size

   * is given by KEXEC_CONTROL_PAGE_SIZE.  In the best case only a single

   * page of memory is necessary, but some architectures require more.
   * Because this memory must be identity mapped in the transition from
   * virtual to physical addresses it must live in the range
   * 0 - TASK_SIZE, as only the user space mappings are arbitrarily
   * modifiable.
   *
   * The assembly stub in the control code buffer is passed a linked list
   * of descriptor pages detailing the source pages of the new kernel,
   * and the destination addresses of those source pages.  As this data
   * structure is not used in the context of the current OS, it must
   * be self-contained.
   *
   * The code has been made to work with highmem pages and will use a
   * destination page in its final resting place (if it happens
   * to allocate it).  The end product of this is that most of the
   * physical address space, and most of RAM can be used.
   *
   * Future directions include:
   *  - allocating a page table with the control code buffer identity
   *    mapped, to simplify machine_kexec and make kexec_on_panic more
   *    reliable.
   */
  
  /*
   * KIMAGE_NO_DEST is an impossible destination address..., for
   * allocating pages whose destination address we do not care about.
   */
  #define KIMAGE_NO_DEST (-1UL)

  static int kimage_is_destination_range(struct kimage *image,
  				       unsigned long start, unsigned long end);
  static struct page *kimage_alloc_page(struct kimage *image,

  				       gfp_t gfp_mask,

  				       unsigned long dest);

  static int copy_user_segment_list(struct kimage *image,
  				  unsigned long nr_segments,
  				  struct kexec_segment __user *segments)

  {

  	int ret;

  	size_t segment_bytes;

  
  	/* Read in the segments */
  	image->nr_segments = nr_segments;
  	segment_bytes = nr_segments * sizeof(*segments);

  	ret = copy_from_user(image->segment, segments, segment_bytes);
  	if (ret)
  		ret = -EFAULT;
  
  	return ret;
  }
  
  static int sanity_check_segment_list(struct kimage *image)
  {
  	int result, i;
  	unsigned long nr_segments = image->nr_segments;

  
  	/*
  	 * Verify we have good destination addresses.  The caller is
  	 * responsible for making certain we don't attempt to load
  	 * the new image into invalid or reserved areas of RAM.  This
  	 * just verifies it is an address we can use.
  	 *
  	 * Since the kernel does everything in page size chunks ensure

  	 * the destination addresses are page aligned.  Too many

  	 * special cases crop of when we don't do this.  The most
  	 * insidious is getting overlapping destination addresses
  	 * simply because addresses are changed to page size
  	 * granularity.
  	 */
  	result = -EADDRNOTAVAIL;
  	for (i = 0; i < nr_segments; i++) {
  		unsigned long mstart, mend;

  		mstart = image->segment[i].mem;
  		mend   = mstart + image->segment[i].memsz;
  		if ((mstart & ~PAGE_MASK) || (mend & ~PAGE_MASK))

  			return result;

  		if (mend >= KEXEC_DESTINATION_MEMORY_LIMIT)

  			return result;

  	}
  
  	/* Verify our destination addresses do not overlap.
  	 * If we alloed overlapping destination addresses
  	 * through very weird things can happen with no
  	 * easy explanation as one segment stops on another.
  	 */
  	result = -EINVAL;

  	for (i = 0; i < nr_segments; i++) {

  		unsigned long mstart, mend;
  		unsigned long j;

  		mstart = image->segment[i].mem;
  		mend   = mstart + image->segment[i].memsz;

  		for (j = 0; j < i; j++) {

  			unsigned long pstart, pend;
  			pstart = image->segment[j].mem;
  			pend   = pstart + image->segment[j].memsz;
  			/* Do the segments overlap ? */
  			if ((mend > pstart) && (mstart < pend))

  				return result;

  		}
  	}
  
  	/* Ensure our buffer sizes are strictly less than
  	 * our memory sizes.  This should always be the case,
  	 * and it is easier to check up front than to be surprised
  	 * later on.
  	 */
  	result = -EINVAL;

  	for (i = 0; i < nr_segments; i++) {

  		if (image->segment[i].bufsz > image->segment[i].memsz)

  			return result;

  	}

  	/*
  	 * Verify we have good destination addresses.  Normally
  	 * the caller is responsible for making certain we don't
  	 * attempt to load the new image into invalid or reserved
  	 * areas of RAM.  But crash kernels are preloaded into a
  	 * reserved area of ram.  We must ensure the addresses
  	 * are in the reserved area otherwise preloading the
  	 * kernel could corrupt things.
  	 */

  	if (image->type == KEXEC_TYPE_CRASH) {
  		result = -EADDRNOTAVAIL;
  		for (i = 0; i < nr_segments; i++) {
  			unsigned long mstart, mend;
  
  			mstart = image->segment[i].mem;
  			mend = mstart + image->segment[i].memsz - 1;
  			/* Ensure we are within the crash kernel limits */
  			if ((mstart < crashk_res.start) ||
  			    (mend > crashk_res.end))
  				return result;
  		}
  	}

  	return 0;
  }
  
  static struct kimage *do_kimage_alloc_init(void)
  {
  	struct kimage *image;
  
  	/* Allocate a controlling structure */
  	image = kzalloc(sizeof(*image), GFP_KERNEL);
  	if (!image)
  		return NULL;
  
  	image->head = 0;
  	image->entry = &image->head;
  	image->last_entry = &image->head;
  	image->control_page = ~0; /* By default this does not apply */
  	image->type = KEXEC_TYPE_DEFAULT;
  
  	/* Initialize the list of control pages */
  	INIT_LIST_HEAD(&image->control_pages);
  
  	/* Initialize the list of destination pages */
  	INIT_LIST_HEAD(&image->dest_pages);
  
  	/* Initialize the list of unusable pages */
  	INIT_LIST_HEAD(&image->unusable_pages);
  
  	return image;

  }

  static void kimage_free_page_list(struct list_head *list);

  static int kimage_alloc_init(struct kimage **rimage, unsigned long entry,
  			     unsigned long nr_segments,
  			     struct kexec_segment __user *segments,
  			     unsigned long flags)

  {

  	int ret;

  	struct kimage *image;

  	bool kexec_on_panic = flags & KEXEC_ON_CRASH;
  
  	if (kexec_on_panic) {
  		/* Verify we have a valid entry point */
  		if ((entry < crashk_res.start) || (entry > crashk_res.end))
  			return -EADDRNOTAVAIL;
  	}

  
  	/* Allocate and initialize a controlling structure */

  	image = do_kimage_alloc_init();
  	if (!image)
  		return -ENOMEM;
  
  	image->start = entry;

  	ret = copy_user_segment_list(image, nr_segments, segments);
  	if (ret)

  		goto out_free_image;

  	ret = sanity_check_segment_list(image);
  	if (ret)

  		goto out_free_image;

  	 /* Enable the special crash kernel control page allocation policy. */
  	if (kexec_on_panic) {
  		image->control_page = crashk_res.start;
  		image->type = KEXEC_TYPE_CRASH;
  	}

  	/*
  	 * Find a location for the control code buffer, and add it
  	 * the vector of segments so that it's pages will also be
  	 * counted as destination pages.
  	 */

  	ret = -ENOMEM;

  	image->control_code_page = kimage_alloc_control_pages(image,

  					   get_order(KEXEC_CONTROL_PAGE_SIZE));

  	if (!image->control_code_page) {

  		pr_err("Could not allocate control_code_buffer
  ");

  		goto out_free_image;

  	}

  	if (!kexec_on_panic) {
  		image->swap_page = kimage_alloc_control_pages(image, 0);
  		if (!image->swap_page) {
  			pr_err("Could not allocate swap buffer
  ");
  			goto out_free_control_pages;
  		}

  	}

  	*rimage = image;
  	return 0;

  out_free_control_pages:

  	kimage_free_page_list(&image->control_pages);

  out_free_image:

  	kfree(image);

  	return ret;

  }

  #ifdef CONFIG_KEXEC_FILE

  static int copy_file_from_fd(int fd, void **buf, unsigned long *buf_len)
  {
  	struct fd f = fdget(fd);
  	int ret;
  	struct kstat stat;
  	loff_t pos;
  	ssize_t bytes = 0;
  
  	if (!f.file)
  		return -EBADF;
  
  	ret = vfs_getattr(&f.file->f_path, &stat);
  	if (ret)
  		goto out;
  
  	if (stat.size > INT_MAX) {
  		ret = -EFBIG;
  		goto out;
  	}
  
  	/* Don't hand 0 to vmalloc, it whines. */
  	if (stat.size == 0) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	*buf = vmalloc(stat.size);
  	if (!*buf) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	pos = 0;
  	while (pos < stat.size) {
  		bytes = kernel_read(f.file, pos, (char *)(*buf) + pos,
  				    stat.size - pos);
  		if (bytes < 0) {
  			vfree(*buf);
  			ret = bytes;
  			goto out;
  		}
  
  		if (bytes == 0)
  			break;
  		pos += bytes;
  	}
  
  	if (pos != stat.size) {
  		ret = -EBADF;
  		vfree(*buf);
  		goto out;
  	}
  
  	*buf_len = pos;
  out:
  	fdput(f);
  	return ret;
  }
  
  /* Architectures can provide this probe function */
  int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
  					 unsigned long buf_len)
  {
  	return -ENOEXEC;
  }
  
  void * __weak arch_kexec_kernel_image_load(struct kimage *image)
  {
  	return ERR_PTR(-ENOEXEC);
  }
  
  void __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
  {
  }

  int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
  					unsigned long buf_len)
  {
  	return -EKEYREJECTED;
  }

  /* Apply relocations of type RELA */
  int __weak
  arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
  				 unsigned int relsec)
  {
  	pr_err("RELA relocation unsupported.
  ");
  	return -ENOEXEC;
  }
  
  /* Apply relocations of type REL */
  int __weak
  arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
  			     unsigned int relsec)
  {
  	pr_err("REL relocation unsupported.
  ");
  	return -ENOEXEC;
  }

  /*

   * Free up memory used by kernel, initrd, and command line. This is temporary

   * memory allocation which is not needed any more after these buffers have
   * been loaded into separate segments and have been copied elsewhere.
   */
  static void kimage_file_post_load_cleanup(struct kimage *image)
  {

  	struct purgatory_info *pi = &image->purgatory_info;

  	vfree(image->kernel_buf);
  	image->kernel_buf = NULL;
  
  	vfree(image->initrd_buf);
  	image->initrd_buf = NULL;
  
  	kfree(image->cmdline_buf);
  	image->cmdline_buf = NULL;

  	vfree(pi->purgatory_buf);
  	pi->purgatory_buf = NULL;
  
  	vfree(pi->sechdrs);
  	pi->sechdrs = NULL;

  	/* See if architecture has anything to cleanup post load */
  	arch_kimage_file_post_load_cleanup(image);

  
  	/*
  	 * Above call should have called into bootloader to free up
  	 * any data stored in kimage->image_loader_data. It should
  	 * be ok now to free it up.
  	 */
  	kfree(image->image_loader_data);
  	image->image_loader_data = NULL;

  }
  
  /*
   * In file mode list of segments is prepared by kernel. Copy relevant
   * data from user space, do error checking, prepare segment list
   */
  static int
  kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
  			     const char __user *cmdline_ptr,
  			     unsigned long cmdline_len, unsigned flags)
  {
  	int ret = 0;
  	void *ldata;
  
  	ret = copy_file_from_fd(kernel_fd, &image->kernel_buf,
  				&image->kernel_buf_len);
  	if (ret)
  		return ret;
  
  	/* Call arch image probe handlers */
  	ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
  					    image->kernel_buf_len);
  
  	if (ret)
  		goto out;

  #ifdef CONFIG_KEXEC_VERIFY_SIG
  	ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf,
  					   image->kernel_buf_len);
  	if (ret) {
  		pr_debug("kernel signature verification failed.
  ");
  		goto out;
  	}
  	pr_debug("kernel signature verification successful.
  ");
  #endif

  	/* It is possible that there no initramfs is being loaded */
  	if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
  		ret = copy_file_from_fd(initrd_fd, &image->initrd_buf,
  					&image->initrd_buf_len);
  		if (ret)
  			goto out;
  	}
  
  	if (cmdline_len) {
  		image->cmdline_buf = kzalloc(cmdline_len, GFP_KERNEL);
  		if (!image->cmdline_buf) {
  			ret = -ENOMEM;
  			goto out;
  		}
  
  		ret = copy_from_user(image->cmdline_buf, cmdline_ptr,
  				     cmdline_len);
  		if (ret) {
  			ret = -EFAULT;
  			goto out;
  		}
  
  		image->cmdline_buf_len = cmdline_len;
  
  		/* command line should be a string with last byte null */
  		if (image->cmdline_buf[cmdline_len - 1] != '\0') {
  			ret = -EINVAL;
  			goto out;
  		}
  	}
  
  	/* Call arch image load handlers */
  	ldata = arch_kexec_kernel_image_load(image);
  
  	if (IS_ERR(ldata)) {
  		ret = PTR_ERR(ldata);
  		goto out;
  	}
  
  	image->image_loader_data = ldata;
  out:
  	/* In case of error, free up all allocated memory in this function */
  	if (ret)
  		kimage_file_post_load_cleanup(image);
  	return ret;
  }
  
  static int
  kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
  		       int initrd_fd, const char __user *cmdline_ptr,
  		       unsigned long cmdline_len, unsigned long flags)
  {
  	int ret;
  	struct kimage *image;

  	bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH;

  
  	image = do_kimage_alloc_init();
  	if (!image)
  		return -ENOMEM;
  
  	image->file_mode = 1;

  	if (kexec_on_panic) {
  		/* Enable special crash kernel control page alloc policy. */
  		image->control_page = crashk_res.start;
  		image->type = KEXEC_TYPE_CRASH;
  	}

  	ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
  					   cmdline_ptr, cmdline_len, flags);
  	if (ret)
  		goto out_free_image;
  
  	ret = sanity_check_segment_list(image);
  	if (ret)
  		goto out_free_post_load_bufs;
  
  	ret = -ENOMEM;
  	image->control_code_page = kimage_alloc_control_pages(image,
  					   get_order(KEXEC_CONTROL_PAGE_SIZE));
  	if (!image->control_code_page) {
  		pr_err("Could not allocate control_code_buffer
  ");
  		goto out_free_post_load_bufs;
  	}

  	if (!kexec_on_panic) {
  		image->swap_page = kimage_alloc_control_pages(image, 0);
  		if (!image->swap_page) {

  			pr_err("Could not allocate swap buffer
  ");

  			goto out_free_control_pages;
  		}

  	}
  
  	*rimage = image;
  	return 0;
  out_free_control_pages:
  	kimage_free_page_list(&image->control_pages);
  out_free_post_load_bufs:
  	kimage_file_post_load_cleanup(image);

  out_free_image:
  	kfree(image);
  	return ret;
  }

  #else /* CONFIG_KEXEC_FILE */
  static inline void kimage_file_post_load_cleanup(struct kimage *image) { }
  #endif /* CONFIG_KEXEC_FILE */

  static int kimage_is_destination_range(struct kimage *image,
  					unsigned long start,
  					unsigned long end)

  {
  	unsigned long i;
  
  	for (i = 0; i < image->nr_segments; i++) {
  		unsigned long mstart, mend;

  		mstart = image->segment[i].mem;

  		mend = mstart + image->segment[i].memsz;
  		if ((end > mstart) && (start < mend))

  			return 1;

  	}

  	return 0;
  }

  static struct page *kimage_alloc_pages(gfp_t gfp_mask, unsigned int order)

  {
  	struct page *pages;

  	pages = alloc_pages(gfp_mask, order);
  	if (pages) {
  		unsigned int count, i;
  		pages->mapping = NULL;

  		set_page_private(pages, order);

  		count = 1 << order;

  		for (i = 0; i < count; i++)

  			SetPageReserved(pages + i);

  	}

  	return pages;
  }
  
  static void kimage_free_pages(struct page *page)
  {
  	unsigned int order, count, i;

  	order = page_private(page);

  	count = 1 << order;

  	for (i = 0; i < count; i++)

  		ClearPageReserved(page + i);

  	__free_pages(page, order);
  }
  
  static void kimage_free_page_list(struct list_head *list)
  {
  	struct list_head *pos, *next;

  	list_for_each_safe(pos, next, list) {
  		struct page *page;
  
  		page = list_entry(pos, struct page, lru);
  		list_del(&page->lru);

  		kimage_free_pages(page);
  	}
  }

  static struct page *kimage_alloc_normal_control_pages(struct kimage *image,
  							unsigned int order)

  {
  	/* Control pages are special, they are the intermediaries
  	 * that are needed while we copy the rest of the pages
  	 * to their final resting place.  As such they must
  	 * not conflict with either the destination addresses
  	 * or memory the kernel is already using.
  	 *
  	 * The only case where we really need more than one of
  	 * these are for architectures where we cannot disable
  	 * the MMU and must instead generate an identity mapped
  	 * page table for all of the memory.
  	 *
  	 * At worst this runs in O(N) of the image size.
  	 */
  	struct list_head extra_pages;
  	struct page *pages;
  	unsigned int count;
  
  	count = 1 << order;
  	INIT_LIST_HEAD(&extra_pages);
  
  	/* Loop while I can allocate a page and the page allocated
  	 * is a destination page.
  	 */
  	do {
  		unsigned long pfn, epfn, addr, eaddr;

  		pages = kimage_alloc_pages(KEXEC_CONTROL_MEMORY_GFP, order);

  		if (!pages)
  			break;
  		pfn   = page_to_pfn(pages);
  		epfn  = pfn + count;
  		addr  = pfn << PAGE_SHIFT;
  		eaddr = epfn << PAGE_SHIFT;
  		if ((epfn >= (KEXEC_CONTROL_MEMORY_LIMIT >> PAGE_SHIFT)) ||

  			      kimage_is_destination_range(image, addr, eaddr)) {

  			list_add(&pages->lru, &extra_pages);
  			pages = NULL;
  		}

  	} while (!pages);

  	if (pages) {
  		/* Remember the allocated page... */
  		list_add(&pages->lru, &image->control_pages);
  
  		/* Because the page is already in it's destination
  		 * location we will never allocate another page at
  		 * that address.  Therefore kimage_alloc_pages
  		 * will not return it (again) and we don't need
  		 * to give it an entry in image->segment[].
  		 */
  	}
  	/* Deal with the destination pages I have inadvertently allocated.
  	 *
  	 * Ideally I would convert multi-page allocations into single

  	 * page allocations, and add everything to image->dest_pages.

  	 *
  	 * For now it is simpler to just free the pages.
  	 */
  	kimage_free_page_list(&extra_pages);

  	return pages;

  }

  static struct page *kimage_alloc_crash_control_pages(struct kimage *image,
  						      unsigned int order)

  {
  	/* Control pages are special, they are the intermediaries
  	 * that are needed while we copy the rest of the pages
  	 * to their final resting place.  As such they must
  	 * not conflict with either the destination addresses
  	 * or memory the kernel is already using.
  	 *
  	 * Control pages are also the only pags we must allocate
  	 * when loading a crash kernel.  All of the other pages
  	 * are specified by the segments and we just memcpy
  	 * into them directly.
  	 *
  	 * The only case where we really need more than one of
  	 * these are for architectures where we cannot disable
  	 * the MMU and must instead generate an identity mapped
  	 * page table for all of the memory.
  	 *
  	 * Given the low demand this implements a very simple
  	 * allocator that finds the first hole of the appropriate
  	 * size in the reserved memory region, and allocates all
  	 * of the memory up to and including the hole.
  	 */
  	unsigned long hole_start, hole_end, size;
  	struct page *pages;

  	pages = NULL;
  	size = (1 << order) << PAGE_SHIFT;
  	hole_start = (image->control_page + (size - 1)) & ~(size - 1);
  	hole_end   = hole_start + size - 1;

  	while (hole_end <= crashk_res.end) {

  		unsigned long i;

  		if (hole_end > KEXEC_CRASH_CONTROL_MEMORY_LIMIT)

  			break;

  		/* See if I overlap any of the segments */

  		for (i = 0; i < image->nr_segments; i++) {

  			unsigned long mstart, mend;

  			mstart = image->segment[i].mem;
  			mend   = mstart + image->segment[i].memsz - 1;
  			if ((hole_end >= mstart) && (hole_start <= mend)) {
  				/* Advance the hole to the end of the segment */
  				hole_start = (mend + (size - 1)) & ~(size - 1);
  				hole_end   = hole_start + size - 1;
  				break;
  			}
  		}
  		/* If I don't overlap any segments I have found my hole! */
  		if (i == image->nr_segments) {
  			pages = pfn_to_page(hole_start >> PAGE_SHIFT);
  			break;
  		}
  	}

  	if (pages)

  		image->control_page = hole_end;

  	return pages;
  }

  struct page *kimage_alloc_control_pages(struct kimage *image,
  					 unsigned int order)

  {
  	struct page *pages = NULL;

  
  	switch (image->type) {

  	case KEXEC_TYPE_DEFAULT:
  		pages = kimage_alloc_normal_control_pages(image, order);
  		break;
  	case KEXEC_TYPE_CRASH:
  		pages = kimage_alloc_crash_control_pages(image, order);
  		break;
  	}

  	return pages;
  }
  
  static int kimage_add_entry(struct kimage *image, kimage_entry_t entry)
  {

  	if (*image->entry != 0)

  		image->entry++;

  	if (image->entry == image->last_entry) {
  		kimage_entry_t *ind_page;
  		struct page *page;

  		page = kimage_alloc_page(image, GFP_KERNEL, KIMAGE_NO_DEST);

  		if (!page)

  			return -ENOMEM;

  		ind_page = page_address(page);
  		*image->entry = virt_to_phys(ind_page) | IND_INDIRECTION;
  		image->entry = ind_page;

  		image->last_entry = ind_page +
  				      ((PAGE_SIZE/sizeof(kimage_entry_t)) - 1);

  	}
  	*image->entry = entry;
  	image->entry++;
  	*image->entry = 0;

  	return 0;
  }

  static int kimage_set_destination(struct kimage *image,
  				   unsigned long destination)

  {
  	int result;
  
  	destination &= PAGE_MASK;
  	result = kimage_add_entry(image, destination | IND_DESTINATION);

  	return result;
  }
  
  
  static int kimage_add_page(struct kimage *image, unsigned long page)
  {
  	int result;
  
  	page &= PAGE_MASK;
  	result = kimage_add_entry(image, page | IND_SOURCE);

  	return result;
  }
  
  
  static void kimage_free_extra_pages(struct kimage *image)
  {
  	/* Walk through and free any extra destination pages I may have */
  	kimage_free_page_list(&image->dest_pages);

  	/* Walk through and free any unusable pages I have cached */

  	kimage_free_page_list(&image->unusable_pages);

  
  }

  static void kimage_terminate(struct kimage *image)

  {

  	if (*image->entry != 0)

  		image->entry++;

  	*image->entry = IND_DONE;

  }
  
  #define for_each_kimage_entry(image, ptr, entry) \
  	for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); \

  		ptr = (entry & IND_INDIRECTION) ? \
  			phys_to_virt((entry & PAGE_MASK)) : ptr + 1)

  
  static void kimage_free_entry(kimage_entry_t entry)
  {
  	struct page *page;
  
  	page = pfn_to_page(entry >> PAGE_SHIFT);
  	kimage_free_pages(page);
  }
  
  static void kimage_free(struct kimage *image)
  {
  	kimage_entry_t *ptr, entry;
  	kimage_entry_t ind = 0;
  
  	if (!image)
  		return;

  	kimage_free_extra_pages(image);
  	for_each_kimage_entry(image, ptr, entry) {
  		if (entry & IND_INDIRECTION) {
  			/* Free the previous indirection page */

  			if (ind & IND_INDIRECTION)

  				kimage_free_entry(ind);

  			/* Save this indirection page until we are
  			 * done with it.
  			 */
  			ind = entry;

  		} else if (entry & IND_SOURCE)

  			kimage_free_entry(entry);

  	}
  	/* Free the final indirection page */

  	if (ind & IND_INDIRECTION)

  		kimage_free_entry(ind);

  
  	/* Handle any machine specific cleanup */
  	machine_kexec_cleanup(image);
  
  	/* Free the kexec control pages... */
  	kimage_free_page_list(&image->control_pages);

  	/*
  	 * Free up any temporary buffers allocated. This might hit if
  	 * error occurred much later after buffer allocation.
  	 */
  	if (image->file_mode)
  		kimage_file_post_load_cleanup(image);

  	kfree(image);
  }

  static kimage_entry_t *kimage_dst_used(struct kimage *image,
  					unsigned long page)

  {
  	kimage_entry_t *ptr, entry;
  	unsigned long destination = 0;
  
  	for_each_kimage_entry(image, ptr, entry) {

  		if (entry & IND_DESTINATION)

  			destination = entry & PAGE_MASK;

  		else if (entry & IND_SOURCE) {

  			if (page == destination)

  				return ptr;

  			destination += PAGE_SIZE;
  		}
  	}

  	return NULL;

  }

  static struct page *kimage_alloc_page(struct kimage *image,

  					gfp_t gfp_mask,

  					unsigned long destination)

  {
  	/*
  	 * Here we implement safeguards to ensure that a source page
  	 * is not copied to its destination page before the data on
  	 * the destination page is no longer useful.
  	 *
  	 * To do this we maintain the invariant that a source page is
  	 * either its own destination page, or it is not a
  	 * destination page at all.
  	 *
  	 * That is slightly stronger than required, but the proof
  	 * that no problems will not occur is trivial, and the
  	 * implementation is simply to verify.
  	 *
  	 * When allocating all pages normally this algorithm will run
  	 * in O(N) time, but in the worst case it will run in O(N^2)
  	 * time.   If the runtime is a problem the data structures can
  	 * be fixed.
  	 */
  	struct page *page;
  	unsigned long addr;
  
  	/*
  	 * Walk through the list of destination pages, and see if I
  	 * have a match.
  	 */
  	list_for_each_entry(page, &image->dest_pages, lru) {
  		addr = page_to_pfn(page) << PAGE_SHIFT;
  		if (addr == destination) {
  			list_del(&page->lru);
  			return page;
  		}
  	}
  	page = NULL;
  	while (1) {
  		kimage_entry_t *old;
  
  		/* Allocate a page, if we run out of memory give up */
  		page = kimage_alloc_pages(gfp_mask, 0);

  		if (!page)

  			return NULL;

  		/* If the page cannot be used file it away */

  		if (page_to_pfn(page) >
  				(KEXEC_SOURCE_MEMORY_LIMIT >> PAGE_SHIFT)) {

  			list_add(&page->lru, &image->unusable_pages);

  			continue;
  		}
  		addr = page_to_pfn(page) << PAGE_SHIFT;
  
  		/* If it is the destination page we want use it */
  		if (addr == destination)
  			break;
  
  		/* If the page is not a destination page use it */

  		if (!kimage_is_destination_range(image, addr,
  						  addr + PAGE_SIZE))

  			break;
  
  		/*
  		 * I know that the page is someones destination page.
  		 * See if there is already a source page for this
  		 * destination page.  And if so swap the source pages.
  		 */
  		old = kimage_dst_used(image, addr);
  		if (old) {
  			/* If so move it */
  			unsigned long old_addr;
  			struct page *old_page;
  
  			old_addr = *old & PAGE_MASK;
  			old_page = pfn_to_page(old_addr >> PAGE_SHIFT);
  			copy_highpage(page, old_page);
  			*old = addr | (*old & ~PAGE_MASK);
  
  			/* The old page I have found cannot be a

  			 * destination page, so return it if it's
  			 * gfp_flags honor the ones passed in.

  			 */

  			if (!(gfp_mask & __GFP_HIGHMEM) &&
  			    PageHighMem(old_page)) {
  				kimage_free_pages(old_page);
  				continue;
  			}

  			addr = old_addr;
  			page = old_page;
  			break;

  		} else {

  			/* Place the page on the destination list I
  			 * will use it later.
  			 */
  			list_add(&page->lru, &image->dest_pages);
  		}
  	}

  	return page;
  }
  
  static int kimage_load_normal_segment(struct kimage *image,

  					 struct kexec_segment *segment)

  {
  	unsigned long maddr;

  	size_t ubytes, mbytes;

  	int result;

  	unsigned char __user *buf = NULL;
  	unsigned char *kbuf = NULL;

  
  	result = 0;

  	if (image->file_mode)
  		kbuf = segment->kbuf;
  	else
  		buf = segment->buf;

  	ubytes = segment->bufsz;
  	mbytes = segment->memsz;
  	maddr = segment->mem;
  
  	result = kimage_set_destination(image, maddr);

  	if (result < 0)

  		goto out;

  
  	while (mbytes) {

  		struct page *page;
  		char *ptr;
  		size_t uchunk, mchunk;

  		page = kimage_alloc_page(image, GFP_HIGHUSER, maddr);

  		if (!page) {

  			result  = -ENOMEM;
  			goto out;
  		}

  		result = kimage_add_page(image, page_to_pfn(page)
  								<< PAGE_SHIFT);
  		if (result < 0)

  			goto out;

  		ptr = kmap(page);
  		/* Start with a clear page */

  		clear_page(ptr);

  		ptr += maddr & ~PAGE_MASK;

  		mchunk = min_t(size_t, mbytes,
  				PAGE_SIZE - (maddr & ~PAGE_MASK));
  		uchunk = min(ubytes, mchunk);

  		/* For file based kexec, source pages are in kernel memory */
  		if (image->file_mode)
  			memcpy(ptr, kbuf, uchunk);
  		else
  			result = copy_from_user(ptr, buf, uchunk);

  		kunmap(page);
  		if (result) {

  			result = -EFAULT;

  			goto out;
  		}
  		ubytes -= uchunk;
  		maddr  += mchunk;

  		if (image->file_mode)
  			kbuf += mchunk;
  		else
  			buf += mchunk;

  		mbytes -= mchunk;
  	}

  out:

  	return result;
  }
  
  static int kimage_load_crash_segment(struct kimage *image,

  					struct kexec_segment *segment)

  {
  	/* For crash dumps kernels we simply copy the data from
  	 * user space to it's destination.
  	 * We do things a page at a time for the sake of kmap.
  	 */
  	unsigned long maddr;

  	size_t ubytes, mbytes;

  	int result;

  	unsigned char __user *buf = NULL;
  	unsigned char *kbuf = NULL;

  
  	result = 0;

  	if (image->file_mode)
  		kbuf = segment->kbuf;
  	else
  		buf = segment->buf;

  	ubytes = segment->bufsz;
  	mbytes = segment->memsz;
  	maddr = segment->mem;

  	while (mbytes) {

  		struct page *page;
  		char *ptr;
  		size_t uchunk, mchunk;

  		page = pfn_to_page(maddr >> PAGE_SHIFT);

  		if (!page) {

  			result  = -ENOMEM;
  			goto out;
  		}
  		ptr = kmap(page);
  		ptr += maddr & ~PAGE_MASK;

  		mchunk = min_t(size_t, mbytes,
  				PAGE_SIZE - (maddr & ~PAGE_MASK));
  		uchunk = min(ubytes, mchunk);
  		if (mchunk > uchunk) {

  			/* Zero the trailing part of the page */
  			memset(ptr + uchunk, 0, mchunk - uchunk);
  		}

  
  		/* For file based kexec, source pages are in kernel memory */
  		if (image->file_mode)
  			memcpy(ptr, kbuf, uchunk);
  		else
  			result = copy_from_user(ptr, buf, uchunk);

  		kexec_flush_icache_page(page);

  		kunmap(page);
  		if (result) {

  			result = -EFAULT;

  			goto out;
  		}
  		ubytes -= uchunk;
  		maddr  += mchunk;

  		if (image->file_mode)
  			kbuf += mchunk;
  		else
  			buf += mchunk;

  		mbytes -= mchunk;
  	}

  out:

  	return result;
  }
  
  static int kimage_load_segment(struct kimage *image,

  				struct kexec_segment *segment)

  {
  	int result = -ENOMEM;

  
  	switch (image->type) {

  	case KEXEC_TYPE_DEFAULT:
  		result = kimage_load_normal_segment(image, segment);
  		break;
  	case KEXEC_TYPE_CRASH:
  		result = kimage_load_crash_segment(image, segment);
  		break;
  	}

  	return result;
  }
  
  /*
   * Exec Kernel system call: for obvious reasons only root may call it.
   *
   * This call breaks up into three pieces.
   * - A generic part which loads the new kernel from the current
   *   address space, and very carefully places the data in the
   *   allocated pages.
   *
   * - A generic part that interacts with the kernel and tells all of
   *   the devices to shut down.  Preventing on-going dmas, and placing
   *   the devices in a consistent state so a later kernel can
   *   reinitialize them.
   *
   * - A machine specific part that includes the syscall number

   *   and then copies the image to it's final destination.  And

   *   jumps into the image at entry.
   *
   * kexec does not sync, or unmount filesystems so if you need
   * that to happen you need to do that yourself.
   */

  struct kimage *kexec_image;
  struct kimage *kexec_crash_image;

  int kexec_load_disabled;

  
  static DEFINE_MUTEX(kexec_mutex);

  SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
  		struct kexec_segment __user *, segments, unsigned long, flags)

  {
  	struct kimage **dest_image, *image;

  	int result;
  
  	/* We only trust the superuser with rebooting the system. */

  	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)

  		return -EPERM;
  
  	/*
  	 * Verify we have a legal set of flags
  	 * This leaves us room for future extensions.
  	 */
  	if ((flags & KEXEC_FLAGS) != (flags & ~KEXEC_ARCH_MASK))
  		return -EINVAL;
  
  	/* Verify we are on the appropriate architecture */
  	if (((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH) &&
  		((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT))

  		return -EINVAL;

  
  	/* Put an artificial cap on the number
  	 * of segments passed to kexec_load.
  	 */
  	if (nr_segments > KEXEC_SEGMENT_MAX)
  		return -EINVAL;
  
  	image = NULL;
  	result = 0;
  
  	/* Because we write directly to the reserved memory
  	 * region when loading crash kernels we need a mutex here to
  	 * prevent multiple crash  kernels from attempting to load
  	 * simultaneously, and to prevent a crash kernel from loading
  	 * over the top of a in use crash kernel.
  	 *
  	 * KISS: always take the mutex.
  	 */

  	if (!mutex_trylock(&kexec_mutex))

  		return -EBUSY;

  	dest_image = &kexec_image;

  	if (flags & KEXEC_ON_CRASH)

  		dest_image = &kexec_crash_image;

  	if (nr_segments > 0) {
  		unsigned long i;

  		if (flags & KEXEC_ON_CRASH) {
  			/*
  			 * Loading another kernel to switch to if this one
  			 * crashes.  Free any current crash dump kernel before

  			 * we corrupt it.
  			 */

  			kimage_free(xchg(&kexec_crash_image, NULL));

  			result = kimage_alloc_init(&image, entry, nr_segments,
  						   segments, flags);

  			crash_map_reserved_pages();

  		} else {
  			/* Loading another kernel to reboot into. */
  
  			result = kimage_alloc_init(&image, entry, nr_segments,
  						   segments, flags);

  		}

  		if (result)

  			goto out;

  		if (flags & KEXEC_PRESERVE_CONTEXT)
  			image->preserve_context = 1;

  		result = machine_kexec_prepare(image);

  		if (result)

  			goto out;

  
  		for (i = 0; i < nr_segments; i++) {

  			result = kimage_load_segment(image, &image->segment[i]);

  			if (result)

  				goto out;

  		}

  		kimage_terminate(image);

  		if (flags & KEXEC_ON_CRASH)
  			crash_unmap_reserved_pages();

  	}
  	/* Install the new kernel, and  Uninstall the old */
  	image = xchg(dest_image, image);

  out:

  	mutex_unlock(&kexec_mutex);

  	kimage_free(image);

  	return result;
  }

  /*
   * Add and remove page tables for crashkernel memory
   *
   * Provide an empty default implementation here -- architecture
   * code may override this
   */
  void __weak crash_map_reserved_pages(void)
  {}
  
  void __weak crash_unmap_reserved_pages(void)
  {}

  #ifdef CONFIG_COMPAT

  COMPAT_SYSCALL_DEFINE4(kexec_load, compat_ulong_t, entry,
  		       compat_ulong_t, nr_segments,
  		       struct compat_kexec_segment __user *, segments,
  		       compat_ulong_t, flags)

  {
  	struct compat_kexec_segment in;
  	struct kexec_segment out, __user *ksegments;
  	unsigned long i, result;
  
  	/* Don't allow clients that don't understand the native
  	 * architecture to do anything.
  	 */

  	if ((flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_DEFAULT)

  		return -EINVAL;

  	if (nr_segments > KEXEC_SEGMENT_MAX)

  		return -EINVAL;

  
  	ksegments = compat_alloc_user_space(nr_segments * sizeof(out));

  	for (i = 0; i < nr_segments; i++) {

  		result = copy_from_user(&in, &segments[i], sizeof(in));

  		if (result)

  			return -EFAULT;

  
  		out.buf   = compat_ptr(in.buf);
  		out.bufsz = in.bufsz;
  		out.mem   = in.mem;
  		out.memsz = in.memsz;
  
  		result = copy_to_user(&ksegments[i], &out, sizeof(out));

  		if (result)

  			return -EFAULT;

  	}
  
  	return sys_kexec_load(entry, nr_segments, ksegments, flags);
  }
  #endif

  #ifdef CONFIG_KEXEC_FILE

  SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
  		unsigned long, cmdline_len, const char __user *, cmdline_ptr,
  		unsigned long, flags)
  {

  	int ret = 0, i;
  	struct kimage **dest_image, *image;
  
  	/* We only trust the superuser with rebooting the system. */
  	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
  		return -EPERM;
  
  	/* Make sure we have a legal set of flags */
  	if (flags != (flags & KEXEC_FILE_FLAGS))
  		return -EINVAL;
  
  	image = NULL;
  
  	if (!mutex_trylock(&kexec_mutex))
  		return -EBUSY;
  
  	dest_image = &kexec_image;
  	if (flags & KEXEC_FILE_ON_CRASH)
  		dest_image = &kexec_crash_image;
  
  	if (flags & KEXEC_FILE_UNLOAD)
  		goto exchange;
  
  	/*
  	 * In case of crash, new kernel gets loaded in reserved region. It is
  	 * same memory where old crash kernel might be loaded. Free any
  	 * current crash dump kernel before we corrupt it.
  	 */
  	if (flags & KEXEC_FILE_ON_CRASH)
  		kimage_free(xchg(&kexec_crash_image, NULL));
  
  	ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr,
  				     cmdline_len, flags);
  	if (ret)
  		goto out;
  
  	ret = machine_kexec_prepare(image);
  	if (ret)
  		goto out;

  	ret = kexec_calculate_store_digests(image);
  	if (ret)
  		goto out;

  	for (i = 0; i < image->nr_segments; i++) {
  		struct kexec_segment *ksegment;
  
  		ksegment = &image->segment[i];
  		pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx
  ",
  			 i, ksegment->buf, ksegment->bufsz, ksegment->mem,
  			 ksegment->memsz);
  
  		ret = kimage_load_segment(image, &image->segment[i]);
  		if (ret)
  			goto out;
  	}
  
  	kimage_terminate(image);
  
  	/*
  	 * Free up any temporary buffers allocated which are not needed
  	 * after image has been loaded
  	 */
  	kimage_file_post_load_cleanup(image);
  exchange:
  	image = xchg(dest_image, image);
  out:
  	mutex_unlock(&kexec_mutex);
  	kimage_free(image);
  	return ret;

  }

  #endif /* CONFIG_KEXEC_FILE */

  void crash_kexec(struct pt_regs *regs)

  {

  	/* Take the kexec_mutex here to prevent sys_kexec_load

  	 * running on one cpu from replacing the crash kernel
  	 * we are using after a panic on a different cpu.
  	 *
  	 * If the crash kernel was not located in a fixed area
  	 * of memory the xchg(&kexec_crash_image) would be
  	 * sufficient.  But since I reuse the memory...
  	 */

  	if (mutex_trylock(&kexec_mutex)) {

  		if (kexec_crash_image) {

  			struct pt_regs fixed_regs;

  			crash_setup_regs(&fixed_regs, regs);

  			crash_save_vmcoreinfo();

  			machine_crash_shutdown(&fixed_regs);

  			machine_kexec(kexec_crash_image);

  		}

  		mutex_unlock(&kexec_mutex);

  	}
  }

  size_t crash_get_memory_size(void)
  {

  	size_t size = 0;

  	mutex_lock(&kexec_mutex);

  	if (crashk_res.end != crashk_res.start)

  		size = resource_size(&crashk_res);

  	mutex_unlock(&kexec_mutex);
  	return size;
  }

  void __weak crash_free_reserved_phys_range(unsigned long begin,
  					   unsigned long end)

  {
  	unsigned long addr;

  	for (addr = begin; addr < end; addr += PAGE_SIZE)
  		free_reserved_page(pfn_to_page(addr >> PAGE_SHIFT));

  }
  
  int crash_shrink_memory(unsigned long new_size)
  {
  	int ret = 0;
  	unsigned long start, end;

  	unsigned long old_size;

  	struct resource *ram_res;

  
  	mutex_lock(&kexec_mutex);
  
  	if (kexec_crash_image) {
  		ret = -ENOENT;
  		goto unlock;
  	}
  	start = crashk_res.start;
  	end = crashk_res.end;

  	old_size = (end == 0) ? 0 : end - start + 1;
  	if (new_size >= old_size) {
  		ret = (new_size == old_size) ? 0 : -EINVAL;

  		goto unlock;
  	}

  	ram_res = kzalloc(sizeof(*ram_res), GFP_KERNEL);
  	if (!ram_res) {
  		ret = -ENOMEM;
  		goto unlock;
  	}

  	start = roundup(start, KEXEC_CRASH_MEM_ALIGN);
  	end = roundup(start + new_size, KEXEC_CRASH_MEM_ALIGN);

  	crash_map_reserved_pages();

  	crash_free_reserved_phys_range(end, crashk_res.end);

  	if ((start == end) && (crashk_res.parent != NULL))

  		release_resource(&crashk_res);

  
  	ram_res->start = end;
  	ram_res->end = crashk_res.end;
  	ram_res->flags = IORESOURCE_BUSY | IORESOURCE_MEM;
  	ram_res->name = "System RAM";

  	crashk_res.end = end - 1;

  
  	insert_resource(&iomem_resource, ram_res);

  	crash_unmap_reserved_pages();

  
  unlock:
  	mutex_unlock(&kexec_mutex);
  	return ret;
  }

  static u32 *append_elf_note(u32 *buf, char *name, unsigned type, void *data,
  			    size_t data_len)
  {
  	struct elf_note note;
  
  	note.n_namesz = strlen(name) + 1;
  	note.n_descsz = data_len;
  	note.n_type   = type;
  	memcpy(buf, &note, sizeof(note));
  	buf += (sizeof(note) + 3)/4;
  	memcpy(buf, name, note.n_namesz);
  	buf += (note.n_namesz + 3)/4;
  	memcpy(buf, data, note.n_descsz);
  	buf += (note.n_descsz + 3)/4;
  
  	return buf;
  }
  
  static void final_note(u32 *buf)
  {
  	struct elf_note note;
  
  	note.n_namesz = 0;
  	note.n_descsz = 0;
  	note.n_type   = 0;
  	memcpy(buf, &note, sizeof(note));
  }
  
  void crash_save_cpu(struct pt_regs *regs, int cpu)
  {
  	struct elf_prstatus prstatus;
  	u32 *buf;

  	if ((cpu < 0) || (cpu >= nr_cpu_ids))

  		return;
  
  	/* Using ELF notes here is opportunistic.
  	 * I need a well defined structure format
  	 * for the data I pass, and I need tags
  	 * on the data to indicate what information I have
  	 * squirrelled away.  ELF notes happen to provide
  	 * all of that, so there is no need to invent something new.
  	 */

  	buf = (u32 *)per_cpu_ptr(crash_notes, cpu);

  	if (!buf)
  		return;
  	memset(&prstatus, 0, sizeof(prstatus));
  	prstatus.pr_pid = current->pid;

  	elf_core_copy_kernel_regs(&prstatus.pr_reg, regs);

  	buf = append_elf_note(buf, KEXEC_CORE_NOTE_NAME, NT_PRSTATUS,

  			      &prstatus, sizeof(prstatus));

  	final_note(buf);
  }

  static int __init crash_notes_memory_init(void)
  {
  	/* Allocate memory for saving cpu registers. */
  	crash_notes = alloc_percpu(note_buf_t);
  	if (!crash_notes) {

  		pr_warn("Kexec: Memory allocation for saving cpu register states failed
  ");

  		return -ENOMEM;
  	}
  	return 0;
  }

  subsys_initcall(crash_notes_memory_init);

  
  /*
   * parsing the "crashkernel" commandline
   *
   * this code is intended to be called from architecture specific code
   */
  
  
  /*
   * This function parses command lines in the format
   *
   *   crashkernel=ramsize-range:size[,...][@offset]
   *
   * The function returns 0 on success and -EINVAL on failure.
   */

  static int __init parse_crashkernel_mem(char *cmdline,
  					unsigned long long system_ram,
  					unsigned long long *crash_size,
  					unsigned long long *crash_base)

  {
  	char *cur = cmdline, *tmp;
  
  	/* for each entry of the comma-separated list */
  	do {
  		unsigned long long start, end = ULLONG_MAX, size;
  
  		/* get the start of the range */
  		start = memparse(cur, &tmp);
  		if (cur == tmp) {

  			pr_warn("crashkernel: Memory value expected
  ");

  			return -EINVAL;
  		}
  		cur = tmp;
  		if (*cur != '-') {

  			pr_warn("crashkernel: '-' expected
  ");

  			return -EINVAL;
  		}
  		cur++;
  
  		/* if no ':' is here, than we read the end */
  		if (*cur != ':') {
  			end = memparse(cur, &tmp);
  			if (cur == tmp) {

  				pr_warn("crashkernel: Memory value expected
  ");

  				return -EINVAL;
  			}
  			cur = tmp;
  			if (end <= start) {

  				pr_warn("crashkernel: end <= start
  ");

  				return -EINVAL;
  			}
  		}
  
  		if (*cur != ':') {

  			pr_warn("crashkernel: ':' expected
  ");

  			return -EINVAL;
  		}
  		cur++;
  
  		size = memparse(cur, &tmp);
  		if (cur == tmp) {

  			pr_warn("Memory value expected
  ");

  			return -EINVAL;
  		}
  		cur = tmp;
  		if (size >= system_ram) {

  			pr_warn("crashkernel: invalid size
  ");

  			return -EINVAL;
  		}
  
  		/* match ? */

  		if (system_ram >= start && system_ram < end) {

  			*crash_size = size;
  			break;
  		}
  	} while (*cur++ == ',');
  
  	if (*crash_size > 0) {

  		while (*cur && *cur != ' ' && *cur != '@')

  			cur++;
  		if (*cur == '@') {
  			cur++;
  			*crash_base = memparse(cur, &tmp);
  			if (cur == tmp) {

  				pr_warn("Memory value expected after '@'
  ");

  				return -EINVAL;
  			}
  		}
  	}
  
  	return 0;
  }
  
  /*
   * That function parses "simple" (old) crashkernel command lines like
   *

   *	crashkernel=size[@offset]

   *
   * It returns 0 on success and -EINVAL on failure.
   */

  static int __init parse_crashkernel_simple(char *cmdline,
  					   unsigned long long *crash_size,
  					   unsigned long long *crash_base)

  {
  	char *cur = cmdline;
  
  	*crash_size = memparse(cmdline, &cur);
  	if (cmdline == cur) {

  		pr_warn("crashkernel: memory value expected
  ");

  		return -EINVAL;
  	}
  
  	if (*cur == '@')
  		*crash_base = memparse(cur+1, &cur);

  	else if (*cur != ' ' && *cur != '\0') {

  		pr_warn("crashkernel: unrecognized char
  ");

  		return -EINVAL;
  	}

  
  	return 0;
  }

  #define SUFFIX_HIGH 0
  #define SUFFIX_LOW  1
  #define SUFFIX_NULL 2
  static __initdata char *suffix_tbl[] = {
  	[SUFFIX_HIGH] = ",high",
  	[SUFFIX_LOW]  = ",low",
  	[SUFFIX_NULL] = NULL,
  };

  /*

   * That function parses "suffix"  crashkernel command lines like
   *
   *	crashkernel=size,[high|low]
   *
   * It returns 0 on success and -EINVAL on failure.

   */

  static int __init parse_crashkernel_suffix(char *cmdline,
  					   unsigned long long	*crash_size,

  					   const char *suffix)
  {
  	char *cur = cmdline;
  
  	*crash_size = memparse(cmdline, &cur);
  	if (cmdline == cur) {
  		pr_warn("crashkernel: memory value expected
  ");
  		return -EINVAL;
  	}
  
  	/* check with suffix */
  	if (strncmp(cur, suffix, strlen(suffix))) {
  		pr_warn("crashkernel: unrecognized char
  ");
  		return -EINVAL;
  	}
  	cur += strlen(suffix);
  	if (*cur != ' ' && *cur != '\0') {
  		pr_warn("crashkernel: unrecognized char
  ");
  		return -EINVAL;
  	}
  
  	return 0;
  }
  
  static __init char *get_last_crashkernel(char *cmdline,
  			     const char *name,
  			     const char *suffix)
  {
  	char *p = cmdline, *ck_cmdline = NULL;
  
  	/* find crashkernel and use the last one if there are more */
  	p = strstr(p, name);
  	while (p) {
  		char *end_p = strchr(p, ' ');
  		char *q;
  
  		if (!end_p)
  			end_p = p + strlen(p);
  
  		if (!suffix) {
  			int i;
  
  			/* skip the one with any known suffix */
  			for (i = 0; suffix_tbl[i]; i++) {
  				q = end_p - strlen(suffix_tbl[i]);
  				if (!strncmp(q, suffix_tbl[i],
  					     strlen(suffix_tbl[i])))
  					goto next;
  			}
  			ck_cmdline = p;
  		} else {
  			q = end_p - strlen(suffix);
  			if (!strncmp(q, suffix, strlen(suffix)))
  				ck_cmdline = p;
  		}
  next:
  		p = strstr(p+1, name);
  	}
  
  	if (!ck_cmdline)
  		return NULL;
  
  	return ck_cmdline;
  }

  static int __init __parse_crashkernel(char *cmdline,

  			     unsigned long long system_ram,
  			     unsigned long long *crash_size,

  			     unsigned long long *crash_base,

  			     const char *name,
  			     const char *suffix)

  {

  	char	*first_colon, *first_space;

  	char	*ck_cmdline;

  
  	BUG_ON(!crash_size || !crash_base);
  	*crash_size = 0;
  	*crash_base = 0;

  	ck_cmdline = get_last_crashkernel(cmdline, name, suffix);

  
  	if (!ck_cmdline)
  		return -EINVAL;

  	ck_cmdline += strlen(name);

  	if (suffix)
  		return parse_crashkernel_suffix(ck_cmdline, crash_size,

  				suffix);

  	/*
  	 * if the commandline contains a ':', then that's the extended
  	 * syntax -- if not, it must be the classic syntax
  	 */
  	first_colon = strchr(ck_cmdline, ':');
  	first_space = strchr(ck_cmdline, ' ');
  	if (first_colon && (!first_space || first_colon < first_space))
  		return parse_crashkernel_mem(ck_cmdline, system_ram,
  				crash_size, crash_base);

  	return parse_crashkernel_simple(ck_cmdline, crash_size, crash_base);

  }

  /*
   * That function is the entry point for command line parsing and should be
   * called from the arch-specific code.
   */

  int __init parse_crashkernel(char *cmdline,
  			     unsigned long long system_ram,
  			     unsigned long long *crash_size,
  			     unsigned long long *crash_base)
  {
  	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,

  					"crashkernel=", NULL);

  }

  
  int __init parse_crashkernel_high(char *cmdline,
  			     unsigned long long system_ram,
  			     unsigned long long *crash_size,
  			     unsigned long long *crash_base)
  {
  	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,

  				"crashkernel=", suffix_tbl[SUFFIX_HIGH]);

  }

  
  int __init parse_crashkernel_low(char *cmdline,
  			     unsigned long long system_ram,
  			     unsigned long long *crash_size,
  			     unsigned long long *crash_base)
  {
  	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,

  				"crashkernel=", suffix_tbl[SUFFIX_LOW]);

  }

  static void update_vmcoreinfo_note(void)

  {

  	u32 *buf = vmcoreinfo_note;

  
  	if (!vmcoreinfo_size)
  		return;

  	buf = append_elf_note(buf, VMCOREINFO_NOTE_NAME, 0, vmcoreinfo_data,
  			      vmcoreinfo_size);

  	final_note(buf);
  }

  void crash_save_vmcoreinfo(void)
  {

  	vmcoreinfo_append_str("CRASHTIME=%ld
  ", get_seconds());

  	update_vmcoreinfo_note();
  }

  void vmcoreinfo_append_str(const char *fmt, ...)
  {
  	va_list args;
  	char buf[0x50];

  	size_t r;

  
  	va_start(args, fmt);

  	r = vscnprintf(buf, sizeof(buf), fmt, args);

  	va_end(args);

  	r = min(r, vmcoreinfo_max_size - vmcoreinfo_size);

  
  	memcpy(&vmcoreinfo_data[vmcoreinfo_size], buf, r);
  
  	vmcoreinfo_size += r;
  }
  
  /*
   * provide an empty default implementation here -- architecture
   * code may override this
   */

  void __weak arch_crash_save_vmcoreinfo(void)

  {}

  unsigned long __weak paddr_vmcoreinfo_note(void)

  {
  	return __pa((unsigned long)(char *)&vmcoreinfo_note);
  }
  
  static int __init crash_save_vmcoreinfo_init(void)
  {

  	VMCOREINFO_OSRELEASE(init_uts_ns.name.release);
  	VMCOREINFO_PAGESIZE(PAGE_SIZE);

  	VMCOREINFO_SYMBOL(init_uts_ns);
  	VMCOREINFO_SYMBOL(node_online_map);

  #ifdef CONFIG_MMU

  	VMCOREINFO_SYMBOL(swapper_pg_dir);

  #endif

  	VMCOREINFO_SYMBOL(_stext);

  	VMCOREINFO_SYMBOL(vmap_area_list);

  
  #ifndef CONFIG_NEED_MULTIPLE_NODES

  	VMCOREINFO_SYMBOL(mem_map);
  	VMCOREINFO_SYMBOL(contig_page_data);

  #endif
  #ifdef CONFIG_SPARSEMEM

  	VMCOREINFO_SYMBOL(mem_section);
  	VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS);

  	VMCOREINFO_STRUCT_SIZE(mem_section);

  	VMCOREINFO_OFFSET(mem_section, section_mem_map);

  #endif

  	VMCOREINFO_STRUCT_SIZE(page);
  	VMCOREINFO_STRUCT_SIZE(pglist_data);
  	VMCOREINFO_STRUCT_SIZE(zone);
  	VMCOREINFO_STRUCT_SIZE(free_area);
  	VMCOREINFO_STRUCT_SIZE(list_head);
  	VMCOREINFO_SIZE(nodemask_t);

  	VMCOREINFO_OFFSET(page, flags);
  	VMCOREINFO_OFFSET(page, _count);
  	VMCOREINFO_OFFSET(page, mapping);
  	VMCOREINFO_OFFSET(page, lru);

  	VMCOREINFO_OFFSET(page, _mapcount);
  	VMCOREINFO_OFFSET(page, private);

  	VMCOREINFO_OFFSET(pglist_data, node_zones);
  	VMCOREINFO_OFFSET(pglist_data, nr_zones);

  #ifdef CONFIG_FLAT_NODE_MEM_MAP

  	VMCOREINFO_OFFSET(pglist_data, node_mem_map);

  #endif

  	VMCOREINFO_OFFSET(pglist_data, node_start_pfn);
  	VMCOREINFO_OFFSET(pglist_data, node_spanned_pages);
  	VMCOREINFO_OFFSET(pglist_data, node_id);
  	VMCOREINFO_OFFSET(zone, free_area);
  	VMCOREINFO_OFFSET(zone, vm_stat);
  	VMCOREINFO_OFFSET(zone, spanned_pages);
  	VMCOREINFO_OFFSET(free_area, free_list);
  	VMCOREINFO_OFFSET(list_head, next);
  	VMCOREINFO_OFFSET(list_head, prev);

  	VMCOREINFO_OFFSET(vmap_area, va_start);
  	VMCOREINFO_OFFSET(vmap_area, list);

  	VMCOREINFO_LENGTH(zone.free_area, MAX_ORDER);

  	log_buf_kexec_setup();

  	VMCOREINFO_LENGTH(free_area.free_list, MIGRATE_TYPES);

  	VMCOREINFO_NUMBER(NR_FREE_PAGES);

  	VMCOREINFO_NUMBER(PG_lru);
  	VMCOREINFO_NUMBER(PG_private);
  	VMCOREINFO_NUMBER(PG_swapcache);

  	VMCOREINFO_NUMBER(PG_slab);

  #ifdef CONFIG_MEMORY_FAILURE
  	VMCOREINFO_NUMBER(PG_hwpoison);
  #endif

  	VMCOREINFO_NUMBER(PG_head_mask);

  	VMCOREINFO_NUMBER(PAGE_BUDDY_MAPCOUNT_VALUE);

  #ifdef CONFIG_HUGETLBFS

  	VMCOREINFO_SYMBOL(free_huge_page);

  #endif

  
  	arch_crash_save_vmcoreinfo();

  	update_vmcoreinfo_note();

  
  	return 0;
  }

  subsys_initcall(crash_save_vmcoreinfo_init);

  #ifdef CONFIG_KEXEC_FILE

  static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
  				    struct kexec_buf *kbuf)
  {
  	struct kimage *image = kbuf->image;
  	unsigned long temp_start, temp_end;
  
  	temp_end = min(end, kbuf->buf_max);
  	temp_start = temp_end - kbuf->memsz;
  
  	do {
  		/* align down start */
  		temp_start = temp_start & (~(kbuf->buf_align - 1));
  
  		if (temp_start < start || temp_start < kbuf->buf_min)
  			return 0;
  
  		temp_end = temp_start + kbuf->memsz - 1;
  
  		/*
  		 * Make sure this does not conflict with any of existing
  		 * segments
  		 */
  		if (kimage_is_destination_range(image, temp_start, temp_end)) {
  			temp_start = temp_start - PAGE_SIZE;
  			continue;
  		}
  
  		/* We found a suitable memory range */
  		break;
  	} while (1);
  
  	/* If we are here, we found a suitable memory range */

  	kbuf->mem = temp_start;

  
  	/* Success, stop navigating through remaining System RAM ranges */
  	return 1;
  }
  
  static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
  				     struct kexec_buf *kbuf)
  {
  	struct kimage *image = kbuf->image;
  	unsigned long temp_start, temp_end;
  
  	temp_start = max(start, kbuf->buf_min);
  
  	do {
  		temp_start = ALIGN(temp_start, kbuf->buf_align);
  		temp_end = temp_start + kbuf->memsz - 1;
  
  		if (temp_end > end || temp_end > kbuf->buf_max)
  			return 0;
  		/*
  		 * Make sure this does not conflict with any of existing
  		 * segments
  		 */
  		if (kimage_is_destination_range(image, temp_start, temp_end)) {
  			temp_start = temp_start + PAGE_SIZE;
  			continue;
  		}
  
  		/* We found a suitable memory range */
  		break;
  	} while (1);
  
  	/* If we are here, we found a suitable memory range */

  	kbuf->mem = temp_start;

  
  	/* Success, stop navigating through remaining System RAM ranges */
  	return 1;
  }
  
  static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
  {
  	struct kexec_buf *kbuf = (struct kexec_buf *)arg;
  	unsigned long sz = end - start + 1;
  
  	/* Returning 0 will take to next memory range */
  	if (sz < kbuf->memsz)
  		return 0;
  
  	if (end < kbuf->buf_min || start > kbuf->buf_max)
  		return 0;
  
  	/*
  	 * Allocate memory top down with-in ram range. Otherwise bottom up
  	 * allocation.
  	 */
  	if (kbuf->top_down)
  		return locate_mem_hole_top_down(start, end, kbuf);
  	return locate_mem_hole_bottom_up(start, end, kbuf);
  }
  
  /*
   * Helper function for placing a buffer in a kexec segment. This assumes
   * that kexec_mutex is held.
   */
  int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
  		     unsigned long memsz, unsigned long buf_align,
  		     unsigned long buf_min, unsigned long buf_max,
  		     bool top_down, unsigned long *load_addr)
  {
  
  	struct kexec_segment *ksegment;
  	struct kexec_buf buf, *kbuf;
  	int ret;
  
  	/* Currently adding segment this way is allowed only in file mode */
  	if (!image->file_mode)
  		return -EINVAL;
  
  	if (image->nr_segments >= KEXEC_SEGMENT_MAX)
  		return -EINVAL;
  
  	/*
  	 * Make sure we are not trying to add buffer after allocating
  	 * control pages. All segments need to be placed first before
  	 * any control pages are allocated. As control page allocation
  	 * logic goes through list of segments to make sure there are
  	 * no destination overlaps.
  	 */
  	if (!list_empty(&image->control_pages)) {
  		WARN_ON(1);
  		return -EINVAL;
  	}
  
  	memset(&buf, 0, sizeof(struct kexec_buf));
  	kbuf = &buf;
  	kbuf->image = image;
  	kbuf->buffer = buffer;
  	kbuf->bufsz = bufsz;
  
  	kbuf->memsz = ALIGN(memsz, PAGE_SIZE);
  	kbuf->buf_align = max(buf_align, PAGE_SIZE);
  	kbuf->buf_min = buf_min;
  	kbuf->buf_max = buf_max;
  	kbuf->top_down = top_down;
  
  	/* Walk the RAM ranges and allocate a suitable range for the buffer */

  	if (image->type == KEXEC_TYPE_CRASH)
  		ret = walk_iomem_res("Crash kernel",
  				     IORESOURCE_MEM | IORESOURCE_BUSY,
  				     crashk_res.start, crashk_res.end, kbuf,
  				     locate_mem_hole_callback);
  	else
  		ret = walk_system_ram_res(0, -1, kbuf,
  					  locate_mem_hole_callback);

  	if (ret != 1) {
  		/* A suitable memory range could not be found for buffer */
  		return -EADDRNOTAVAIL;
  	}
  
  	/* Found a suitable memory range */

  	ksegment = &image->segment[image->nr_segments];
  	ksegment->kbuf = kbuf->buffer;
  	ksegment->bufsz = kbuf->bufsz;
  	ksegment->mem = kbuf->mem;
  	ksegment->memsz = kbuf->memsz;
  	image->nr_segments++;

  	*load_addr = ksegment->mem;
  	return 0;
  }

  /* Calculate and store the digest of segments */
  static int kexec_calculate_store_digests(struct kimage *image)
  {
  	struct crypto_shash *tfm;
  	struct shash_desc *desc;
  	int ret = 0, i, j, zero_buf_sz, sha_region_sz;
  	size_t desc_size, nullsz;
  	char *digest;
  	void *zero_buf;
  	struct kexec_sha_region *sha_regions;
  	struct purgatory_info *pi = &image->purgatory_info;
  
  	zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
  	zero_buf_sz = PAGE_SIZE;
  
  	tfm = crypto_alloc_shash("sha256", 0, 0);
  	if (IS_ERR(tfm)) {
  		ret = PTR_ERR(tfm);
  		goto out;
  	}
  
  	desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
  	desc = kzalloc(desc_size, GFP_KERNEL);
  	if (!desc) {
  		ret = -ENOMEM;
  		goto out_free_tfm;
  	}
  
  	sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
  	sha_regions = vzalloc(sha_region_sz);
  	if (!sha_regions)
  		goto out_free_desc;
  
  	desc->tfm   = tfm;
  	desc->flags = 0;
  
  	ret = crypto_shash_init(desc);
  	if (ret < 0)
  		goto out_free_sha_regions;
  
  	digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
  	if (!digest) {
  		ret = -ENOMEM;
  		goto out_free_sha_regions;
  	}
  
  	for (j = i = 0; i < image->nr_segments; i++) {
  		struct kexec_segment *ksegment;
  
  		ksegment = &image->segment[i];
  		/*
  		 * Skip purgatory as it will be modified once we put digest
  		 * info in purgatory.
  		 */
  		if (ksegment->kbuf == pi->purgatory_buf)
  			continue;
  
  		ret = crypto_shash_update(desc, ksegment->kbuf,
  					  ksegment->bufsz);
  		if (ret)
  			break;
  
  		/*
  		 * Assume rest of the buffer is filled with zero and
  		 * update digest accordingly.
  		 */
  		nullsz = ksegment->memsz - ksegment->bufsz;
  		while (nullsz) {
  			unsigned long bytes = nullsz;
  
  			if (bytes > zero_buf_sz)
  				bytes = zero_buf_sz;
  			ret = crypto_shash_update(desc, zero_buf, bytes);
  			if (ret)
  				break;
  			nullsz -= bytes;
  		}
  
  		if (ret)
  			break;
  
  		sha_regions[j].start = ksegment->mem;
  		sha_regions[j].len = ksegment->memsz;
  		j++;
  	}
  
  	if (!ret) {
  		ret = crypto_shash_final(desc, digest);
  		if (ret)
  			goto out_free_digest;
  		ret = kexec_purgatory_get_set_symbol(image, "sha_regions",
  						sha_regions, sha_region_sz, 0);
  		if (ret)
  			goto out_free_digest;
  
  		ret = kexec_purgatory_get_set_symbol(image, "sha256_digest",
  						digest, SHA256_DIGEST_SIZE, 0);
  		if (ret)
  			goto out_free_digest;
  	}
  
  out_free_digest:
  	kfree(digest);
  out_free_sha_regions:
  	vfree(sha_regions);
  out_free_desc:
  	kfree(desc);
  out_free_tfm:
  	kfree(tfm);
  out:
  	return ret;
  }
  
  /* Actually load purgatory. Lot of code taken from kexec-tools */
  static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
  				  unsigned long max, int top_down)
  {
  	struct purgatory_info *pi = &image->purgatory_info;
  	unsigned long align, buf_align, bss_align, buf_sz, bss_sz, bss_pad;
  	unsigned long memsz, entry, load_addr, curr_load_addr, bss_addr, offset;
  	unsigned char *buf_addr, *src;
  	int i, ret = 0, entry_sidx = -1;
  	const Elf_Shdr *sechdrs_c;
  	Elf_Shdr *sechdrs = NULL;
  	void *purgatory_buf = NULL;
  
  	/*
  	 * sechdrs_c points to section headers in purgatory and are read
  	 * only. No modifications allowed.
  	 */
  	sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff;
  
  	/*
  	 * We can not modify sechdrs_c[] and its fields. It is read only.
  	 * Copy it over to a local copy where one can store some temporary
  	 * data and free it at the end. We need to modify ->sh_addr and
  	 * ->sh_offset fields to keep track of permanent and temporary
  	 * locations of sections.
  	 */
  	sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr));
  	if (!sechdrs)
  		return -ENOMEM;
  
  	memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr));
  
  	/*
  	 * We seem to have multiple copies of sections. First copy is which
  	 * is embedded in kernel in read only section. Some of these sections
  	 * will be copied to a temporary buffer and relocated. And these
  	 * sections will finally be copied to their final destination at
  	 * segment load time.
  	 *
  	 * Use ->sh_offset to reflect section address in memory. It will
  	 * point to original read only copy if section is not allocatable.
  	 * Otherwise it will point to temporary copy which will be relocated.
  	 *
  	 * Use ->sh_addr to contain final address of the section where it
  	 * will go during execution time.
  	 */
  	for (i = 0; i < pi->ehdr->e_shnum; i++) {
  		if (sechdrs[i].sh_type == SHT_NOBITS)
  			continue;
  
  		sechdrs[i].sh_offset = (unsigned long)pi->ehdr +
  						sechdrs[i].sh_offset;
  	}
  
  	/*
  	 * Identify entry point section and make entry relative to section
  	 * start.
  	 */
  	entry = pi->ehdr->e_entry;
  	for (i = 0; i < pi->ehdr->e_shnum; i++) {
  		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
  			continue;
  
  		if (!(sechdrs[i].sh_flags & SHF_EXECINSTR))
  			continue;
  
  		/* Make entry section relative */
  		if (sechdrs[i].sh_addr <= pi->ehdr->e_entry &&
  		    ((sechdrs[i].sh_addr + sechdrs[i].sh_size) >
  		     pi->ehdr->e_entry)) {
  			entry_sidx = i;
  			entry -= sechdrs[i].sh_addr;
  			break;
  		}
  	}
  
  	/* Determine how much memory is needed to load relocatable object. */
  	buf_align = 1;
  	bss_align = 1;
  	buf_sz = 0;
  	bss_sz = 0;
  
  	for (i = 0; i < pi->ehdr->e_shnum; i++) {
  		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
  			continue;
  
  		align = sechdrs[i].sh_addralign;
  		if (sechdrs[i].sh_type != SHT_NOBITS) {
  			if (buf_align < align)
  				buf_align = align;
  			buf_sz = ALIGN(buf_sz, align);
  			buf_sz += sechdrs[i].sh_size;
  		} else {
  			/* bss section */
  			if (bss_align < align)
  				bss_align = align;
  			bss_sz = ALIGN(bss_sz, align);
  			bss_sz += sechdrs[i].sh_size;
  		}
  	}
  
  	/* Determine the bss padding required to align bss properly */
  	bss_pad = 0;
  	if (buf_sz & (bss_align - 1))
  		bss_pad = bss_align - (buf_sz & (bss_align - 1));
  
  	memsz = buf_sz + bss_pad + bss_sz;
  
  	/* Allocate buffer for purgatory */
  	purgatory_buf = vzalloc(buf_sz);
  	if (!purgatory_buf) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	if (buf_align < bss_align)
  		buf_align = bss_align;
  
  	/* Add buffer to segment list */
  	ret = kexec_add_buffer(image, purgatory_buf, buf_sz, memsz,
  				buf_align, min, max, top_down,
  				&pi->purgatory_load_addr);
  	if (ret)
  		goto out;
  
  	/* Load SHF_ALLOC sections */
  	buf_addr = purgatory_buf;
  	load_addr = curr_load_addr = pi->purgatory_load_addr;
  	bss_addr = load_addr + buf_sz + bss_pad;
  
  	for (i = 0; i < pi->ehdr->e_shnum; i++) {
  		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
  			continue;
  
  		align = sechdrs[i].sh_addralign;
  		if (sechdrs[i].sh_type != SHT_NOBITS) {
  			curr_load_addr = ALIGN(curr_load_addr, align);
  			offset = curr_load_addr - load_addr;
  			/* We already modifed ->sh_offset to keep src addr */
  			src = (char *) sechdrs[i].sh_offset;
  			memcpy(buf_addr + offset, src, sechdrs[i].sh_size);
  
  			/* Store load address and source address of section */
  			sechdrs[i].sh_addr = curr_load_addr;
  
  			/*
  			 * This section got copied to temporary buffer. Update
  			 * ->sh_offset accordingly.
  			 */
  			sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset);
  
  			/* Advance to the next address */
  			curr_load_addr += sechdrs[i].sh_size;
  		} else {
  			bss_addr = ALIGN(bss_addr, align);
  			sechdrs[i].sh_addr = bss_addr;
  			bss_addr += sechdrs[i].sh_size;
  		}
  	}
  
  	/* Update entry point based on load address of text section */
  	if (entry_sidx >= 0)
  		entry += sechdrs[entry_sidx].sh_addr;
  
  	/* Make kernel jump to purgatory after shutdown */
  	image->start = entry;
  
  	/* Used later to get/set symbol values */
  	pi->sechdrs = sechdrs;
  
  	/*
  	 * Used later to identify which section is purgatory and skip it
  	 * from checksumming.
  	 */
  	pi->purgatory_buf = purgatory_buf;
  	return ret;
  out:
  	vfree(sechdrs);
  	vfree(purgatory_buf);
  	return ret;
  }
  
  static int kexec_apply_relocations(struct kimage *image)
  {
  	int i, ret;
  	struct purgatory_info *pi = &image->purgatory_info;
  	Elf_Shdr *sechdrs = pi->sechdrs;
  
  	/* Apply relocations */
  	for (i = 0; i < pi->ehdr->e_shnum; i++) {
  		Elf_Shdr *section, *symtab;
  
  		if (sechdrs[i].sh_type != SHT_RELA &&
  		    sechdrs[i].sh_type != SHT_REL)
  			continue;
  
  		/*
  		 * For section of type SHT_RELA/SHT_REL,
  		 * ->sh_link contains section header index of associated
  		 * symbol table. And ->sh_info contains section header
  		 * index of section to which relocations apply.
  		 */
  		if (sechdrs[i].sh_info >= pi->ehdr->e_shnum ||
  		    sechdrs[i].sh_link >= pi->ehdr->e_shnum)
  			return -ENOEXEC;
  
  		section = &sechdrs[sechdrs[i].sh_info];
  		symtab = &sechdrs[sechdrs[i].sh_link];
  
  		if (!(section->sh_flags & SHF_ALLOC))
  			continue;
  
  		/*
  		 * symtab->sh_link contain section header index of associated
  		 * string table.
  		 */
  		if (symtab->sh_link >= pi->ehdr->e_shnum)
  			/* Invalid section number? */
  			continue;
  
  		/*

  		 * Respective architecture needs to provide support for applying

  		 * relocations of type SHT_RELA/SHT_REL.
  		 */
  		if (sechdrs[i].sh_type == SHT_RELA)
  			ret = arch_kexec_apply_relocations_add(pi->ehdr,
  							       sechdrs, i);
  		else if (sechdrs[i].sh_type == SHT_REL)
  			ret = arch_kexec_apply_relocations(pi->ehdr,
  							   sechdrs, i);
  		if (ret)
  			return ret;
  	}
  
  	return 0;
  }
  
  /* Load relocatable purgatory object and relocate it appropriately */
  int kexec_load_purgatory(struct kimage *image, unsigned long min,
  			 unsigned long max, int top_down,
  			 unsigned long *load_addr)
  {
  	struct purgatory_info *pi = &image->purgatory_info;
  	int ret;
  
  	if (kexec_purgatory_size <= 0)
  		return -EINVAL;
  
  	if (kexec_purgatory_size < sizeof(Elf_Ehdr))
  		return -ENOEXEC;
  
  	pi->ehdr = (Elf_Ehdr *)kexec_purgatory;
  
  	if (memcmp(pi->ehdr->e_ident, ELFMAG, SELFMAG) != 0
  	    || pi->ehdr->e_type != ET_REL
  	    || !elf_check_arch(pi->ehdr)
  	    || pi->ehdr->e_shentsize != sizeof(Elf_Shdr))
  		return -ENOEXEC;
  
  	if (pi->ehdr->e_shoff >= kexec_purgatory_size
  	    || (pi->ehdr->e_shnum * sizeof(Elf_Shdr) >
  	    kexec_purgatory_size - pi->ehdr->e_shoff))
  		return -ENOEXEC;
  
  	ret = __kexec_load_purgatory(image, min, max, top_down);
  	if (ret)
  		return ret;
  
  	ret = kexec_apply_relocations(image);
  	if (ret)
  		goto out;
  
  	*load_addr = pi->purgatory_load_addr;
  	return 0;
  out:
  	vfree(pi->sechdrs);
  	vfree(pi->purgatory_buf);
  	return ret;
  }
  
  static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
  					    const char *name)
  {
  	Elf_Sym *syms;
  	Elf_Shdr *sechdrs;
  	Elf_Ehdr *ehdr;
  	int i, k;
  	const char *strtab;
  
  	if (!pi->sechdrs || !pi->ehdr)
  		return NULL;
  
  	sechdrs = pi->sechdrs;
  	ehdr = pi->ehdr;
  
  	for (i = 0; i < ehdr->e_shnum; i++) {
  		if (sechdrs[i].sh_type != SHT_SYMTAB)
  			continue;
  
  		if (sechdrs[i].sh_link >= ehdr->e_shnum)
  			/* Invalid strtab section number */
  			continue;
  		strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset;
  		syms = (Elf_Sym *)sechdrs[i].sh_offset;
  
  		/* Go through symbols for a match */
  		for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
  			if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
  				continue;
  
  			if (strcmp(strtab + syms[k].st_name, name) != 0)
  				continue;
  
  			if (syms[k].st_shndx == SHN_UNDEF ||
  			    syms[k].st_shndx >= ehdr->e_shnum) {
  				pr_debug("Symbol: %s has bad section index %d.
  ",
  						name, syms[k].st_shndx);
  				return NULL;
  			}
  
  			/* Found the symbol we are looking for */
  			return &syms[k];
  		}
  	}
  
  	return NULL;
  }
  
  void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
  {
  	struct purgatory_info *pi = &image->purgatory_info;
  	Elf_Sym *sym;
  	Elf_Shdr *sechdr;
  
  	sym = kexec_purgatory_find_symbol(pi, name);
  	if (!sym)
  		return ERR_PTR(-EINVAL);
  
  	sechdr = &pi->sechdrs[sym->st_shndx];
  
  	/*
  	 * Returns the address where symbol will finally be loaded after
  	 * kexec_load_segment()
  	 */
  	return (void *)(sechdr->sh_addr + sym->st_value);
  }
  
  /*
   * Get or set value of a symbol. If "get_value" is true, symbol value is
   * returned in buf otherwise symbol value is set based on value in buf.
   */
  int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
  				   void *buf, unsigned int size, bool get_value)
  {
  	Elf_Sym *sym;
  	Elf_Shdr *sechdrs;
  	struct purgatory_info *pi = &image->purgatory_info;
  	char *sym_buf;
  
  	sym = kexec_purgatory_find_symbol(pi, name);
  	if (!sym)
  		return -EINVAL;
  
  	if (sym->st_size != size) {
  		pr_err("symbol %s size mismatch: expected %lu actual %u
  ",
  		       name, (unsigned long)sym->st_size, size);
  		return -EINVAL;
  	}
  
  	sechdrs = pi->sechdrs;
  
  	if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) {
  		pr_err("symbol %s is in a bss section. Cannot %s
  ", name,
  		       get_value ? "get" : "set");
  		return -EINVAL;
  	}
  
  	sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset +
  					sym->st_value;
  
  	if (get_value)
  		memcpy((void *)buf, sym_buf, size);
  	else
  		memcpy((void *)sym_buf, buf, size);
  
  	return 0;
  }

  #endif /* CONFIG_KEXEC_FILE */

  /*
   * Move into place and start executing a preloaded standalone
   * executable.  If nothing was preloaded return an error.

   */
  int kernel_kexec(void)
  {
  	int error = 0;

  	if (!mutex_trylock(&kexec_mutex))

  		return -EBUSY;
  	if (!kexec_image) {
  		error = -EINVAL;
  		goto Unlock;
  	}

  #ifdef CONFIG_KEXEC_JUMP

  	if (kexec_image->preserve_context) {

  		lock_system_sleep();

  		pm_prepare_console();
  		error = freeze_processes();
  		if (error) {
  			error = -EBUSY;
  			goto Restore_console;
  		}
  		suspend_console();

  		error = dpm_suspend_start(PMSG_FREEZE);

  		if (error)
  			goto Resume_console;

  		/* At this point, dpm_suspend_start() has been called,

  		 * but *not* dpm_suspend_end(). We *must* call
  		 * dpm_suspend_end() now.  Otherwise, drivers for

  		 * some devices (e.g. interrupt controllers) become
  		 * desynchronized with the actual state of the
  		 * hardware at resume time, and evil weirdness ensues.
  		 */

  		error = dpm_suspend_end(PMSG_FREEZE);

  		if (error)

  			goto Resume_devices;
  		error = disable_nonboot_cpus();
  		if (error)
  			goto Enable_cpus;

  		local_irq_disable();

  		error = syscore_suspend();

  		if (error)

  			goto Enable_irqs;

  	} else

  #endif

  	{

  		kexec_in_progress = true;

  		kernel_restart_prepare(NULL);

  		migrate_to_reboot_cpu();

  
  		/*
  		 * migrate_to_reboot_cpu() disables CPU hotplug assuming that
  		 * no further code needs to use CPU hotplug (which is true in
  		 * the reboot case). However, the kexec path depends on using
  		 * CPU hotplug again; so re-enable it here.
  		 */
  		cpu_hotplug_enable();

  		pr_emerg("Starting new kernel
  ");

  		machine_shutdown();
  	}
  
  	machine_kexec(kexec_image);

  #ifdef CONFIG_KEXEC_JUMP

  	if (kexec_image->preserve_context) {

  		syscore_resume();

   Enable_irqs:

  		local_irq_enable();

   Enable_cpus:

  		enable_nonboot_cpus();

  		dpm_resume_start(PMSG_RESTORE);

   Resume_devices:

  		dpm_resume_end(PMSG_RESTORE);