// SPDX-License-Identifier: GPL-2.0-only

  /*
   * kexec: kexec_file_load system call
   *
   * Copyright (C) 2014 Red Hat Inc.
   * Authors:
   *      Vivek Goyal <vgoyal@redhat.com>

   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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

  #include <linux/memblock.h>

  #include <linux/mutex.h>
  #include <linux/list.h>

  #include <linux/fs.h>

  #include <linux/ima.h>

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

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

  #include <linux/syscalls.h>
  #include <linux/vmalloc.h>
  #include "kexec_internal.h"

  static int kexec_calculate_store_digests(struct kimage *image);

  /*
   * Currently this is the only default function that is exported as some
   * architectures need it to do additional handlings.
   * In the future, other default functions may be exported too if required.
   */
  int kexec_image_probe_default(struct kimage *image, void *buf,
  			      unsigned long buf_len)
  {
  	const struct kexec_file_ops * const *fops;
  	int ret = -ENOEXEC;
  
  	for (fops = &kexec_file_loaders[0]; *fops && (*fops)->probe; ++fops) {
  		ret = (*fops)->probe(buf, buf_len);
  		if (!ret) {
  			image->fops = *fops;
  			return ret;
  		}
  	}
  
  	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 kexec_image_probe_default(image, buf, buf_len);
  }
  
  static void *kexec_image_load_default(struct kimage *image)
  {
  	if (!image->fops || !image->fops->load)
  		return ERR_PTR(-ENOEXEC);
  
  	return image->fops->load(image, image->kernel_buf,
  				 image->kernel_buf_len, image->initrd_buf,
  				 image->initrd_buf_len, image->cmdline_buf,
  				 image->cmdline_buf_len);

  }
  
  void * __weak arch_kexec_kernel_image_load(struct kimage *image)
  {

  	return kexec_image_load_default(image);
  }

  int kexec_image_post_load_cleanup_default(struct kimage *image)

  {
  	if (!image->fops || !image->fops->cleanup)
  		return 0;
  
  	return image->fops->cleanup(image->image_loader_data);

  }
  
  int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
  {

  	return kexec_image_post_load_cleanup_default(image);

  }

  #ifdef CONFIG_KEXEC_SIG

  static int kexec_image_verify_sig_default(struct kimage *image, void *buf,
  					  unsigned long buf_len)
  {
  	if (!image->fops || !image->fops->verify_sig) {
  		pr_debug("kernel loader does not support signature verification.
  ");
  		return -EKEYREJECTED;
  	}
  
  	return image->fops->verify_sig(buf, buf_len);
  }

  int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
  					unsigned long buf_len)
  {

  	return kexec_image_verify_sig_default(image, buf, buf_len);

  }

  #endif

  /*
   * arch_kexec_apply_relocations_add - apply relocations of type RELA
   * @pi:		Purgatory to be relocated.
   * @section:	Section relocations applying to.
   * @relsec:	Section containing RELAs.
   * @symtab:	Corresponding symtab.
   *
   * Return: 0 on success, negative errno on error.
   */

  int __weak

  arch_kexec_apply_relocations_add(struct purgatory_info *pi, Elf_Shdr *section,
  				 const Elf_Shdr *relsec, const Elf_Shdr *symtab)

  {
  	pr_err("RELA relocation unsupported.
  ");
  	return -ENOEXEC;
  }

  /*
   * arch_kexec_apply_relocations - apply relocations of type REL
   * @pi:		Purgatory to be relocated.
   * @section:	Section relocations applying to.
   * @relsec:	Section containing RELs.
   * @symtab:	Corresponding symtab.
   *
   * Return: 0 on success, negative errno on error.
   */

  int __weak

  arch_kexec_apply_relocations(struct purgatory_info *pi, Elf_Shdr *section,
  			     const Elf_Shdr *relsec, const Elf_Shdr *symtab)

  {
  	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.
   */
  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;
  }

  #ifdef CONFIG_KEXEC_SIG
  static int
  kimage_validate_signature(struct kimage *image)
  {
  	const char *reason;
  	int ret;
  
  	ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf,
  					   image->kernel_buf_len);
  	switch (ret) {
  	case 0:
  		break;
  
  		/* Certain verification errors are non-fatal if we're not
  		 * checking errors, provided we aren't mandating that there
  		 * must be a valid signature.
  		 */
  	case -ENODATA:
  		reason = "kexec of unsigned image";
  		goto decide;
  	case -ENOPKG:
  		reason = "kexec of image with unsupported crypto";
  		goto decide;
  	case -ENOKEY:
  		reason = "kexec of image with unavailable key";
  	decide:
  		if (IS_ENABLED(CONFIG_KEXEC_SIG_FORCE)) {
  			pr_notice("%s rejected
  ", reason);
  			return ret;
  		}

  		/* If IMA is guaranteed to appraise a signature on the kexec
  		 * image, permit it even if the kernel is otherwise locked
  		 * down.
  		 */
  		if (!ima_appraise_signature(READING_KEXEC_IMAGE) &&
  		    security_locked_down(LOCKDOWN_KEXEC))
  			return -EPERM;
  
  		return 0;

  
  		/* All other errors are fatal, including nomem, unparseable
  		 * signatures and signature check failures - even if signatures
  		 * aren't required.
  		 */
  	default:
  		pr_notice("kernel signature verification failed (%d).
  ", ret);
  	}
  
  	return ret;
  }
  #endif

  /*
   * 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;

  	void *ldata;

  	loff_t size;

  	ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf,
  				       &size, INT_MAX, READING_KEXEC_IMAGE);

  	if (ret)
  		return ret;

  	image->kernel_buf_len = size;

  
  	/* 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_SIG
  	ret = kimage_validate_signature(image);
  
  	if (ret)

  		goto out;

  #endif
  	/* It is possible that there no initramfs is being loaded */
  	if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {

  		ret = kernel_read_file_from_fd(initrd_fd, &image->initrd_buf,
  					       &size, INT_MAX,
  					       READING_KEXEC_INITRAMFS);

  		if (ret)
  			goto out;

  		image->initrd_buf_len = size;

  	}
  
  	if (cmdline_len) {

  		image->cmdline_buf = memdup_user(cmdline_ptr, cmdline_len);
  		if (IS_ERR(image->cmdline_buf)) {
  			ret = PTR_ERR(image->cmdline_buf);
  			image->cmdline_buf = NULL;

  			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;
  		}

  
  		ima_kexec_cmdline(image->cmdline_buf,
  				  image->cmdline_buf_len - 1);

  	}

  	/* IMA needs to pass the measurement list to the next kernel. */
  	ima_add_kexec_buffer(image);

  	/* 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;
  }
  
  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 (kexec_crash_image)
  			arch_kexec_unprotect_crashkres();
  	}

  
  	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;

  	/*
  	 * Some architecture(like S390) may touch the crash memory before
  	 * machine_kexec_prepare(), we must copy vmcoreinfo data after it.
  	 */
  	ret = kimage_crash_copy_vmcoreinfo(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:

  	if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
  		arch_kexec_protect_crashkres();

  	mutex_unlock(&kexec_mutex);
  	kimage_free(image);
  	return ret;
  }
  
  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(struct resource *res, void *arg)

  {
  	struct kexec_buf *kbuf = (struct kexec_buf *)arg;

  	u64 start = res->start, end = res->end;

  	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);
  }

  #ifdef CONFIG_ARCH_KEEP_MEMBLOCK

  static int kexec_walk_memblock(struct kexec_buf *kbuf,
  			       int (*func)(struct resource *, void *))
  {
  	int ret = 0;
  	u64 i;
  	phys_addr_t mstart, mend;
  	struct resource res = { };

  	if (kbuf->image->type == KEXEC_TYPE_CRASH)
  		return func(&crashk_res, kbuf);

  	if (kbuf->top_down) {

  		for_each_free_mem_range_reverse(i, NUMA_NO_NODE, MEMBLOCK_NONE,

  						&mstart, &mend, NULL) {
  			/*
  			 * In memblock, end points to the first byte after the
  			 * range while in kexec, end points to the last byte
  			 * in the range.
  			 */
  			res.start = mstart;
  			res.end = mend - 1;
  			ret = func(&res, kbuf);
  			if (ret)
  				break;
  		}
  	} else {

  		for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE,
  					&mstart, &mend, NULL) {

  			/*
  			 * In memblock, end points to the first byte after the
  			 * range while in kexec, end points to the last byte
  			 * in the range.
  			 */
  			res.start = mstart;
  			res.end = mend - 1;
  			ret = func(&res, kbuf);
  			if (ret)
  				break;
  		}
  	}
  
  	return ret;
  }

  #else
  static int kexec_walk_memblock(struct kexec_buf *kbuf,
  			       int (*func)(struct resource *, void *))
  {
  	return 0;
  }

  #endif

  /**

   * kexec_walk_resources - call func(data) on free memory regions

   * @kbuf:	Context info for the search. Also passed to @func.
   * @func:	Function to call for each memory region.
   *
   * Return: The memory walk will stop when func returns a non-zero value
   * and that value will be returned. If all free regions are visited without
   * func returning non-zero, then zero will be returned.
   */

  static int kexec_walk_resources(struct kexec_buf *kbuf,
  				int (*func)(struct resource *, void *))

  {
  	if (kbuf->image->type == KEXEC_TYPE_CRASH)
  		return walk_iomem_res_desc(crashk_res.desc,
  					   IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
  					   crashk_res.start, crashk_res.end,
  					   kbuf, func);
  	else
  		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
  }

  /**

   * kexec_locate_mem_hole - find free memory for the purgatory or the next kernel
   * @kbuf:	Parameters for the memory search.
   *
   * On success, kbuf->mem will have the start address of the memory region found.
   *
   * Return: 0 on success, negative errno on error.
   */
  int kexec_locate_mem_hole(struct kexec_buf *kbuf)
  {
  	int ret;

  	/* Arch knows where to place */
  	if (kbuf->mem != KEXEC_BUF_MEM_UNKNOWN)
  		return 0;

  	if (!IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))

  		ret = kexec_walk_resources(kbuf, locate_mem_hole_callback);
  	else
  		ret = kexec_walk_memblock(kbuf, locate_mem_hole_callback);

  
  	return ret == 1 ? 0 : -EADDRNOTAVAIL;
  }
  
  /**

   * kexec_add_buffer - place a buffer in a kexec segment
   * @kbuf:	Buffer contents and memory parameters.
   *
   * This function assumes that kexec_mutex is held.
   * On successful return, @kbuf->mem will have the physical address of
   * the buffer in memory.
   *
   * Return: 0 on success, negative errno on error.

   */

  int kexec_add_buffer(struct kexec_buf *kbuf)

  {
  
  	struct kexec_segment *ksegment;

  	int ret;
  
  	/* Currently adding segment this way is allowed only in file mode */

  	if (!kbuf->image->file_mode)

  		return -EINVAL;

  	if (kbuf->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(&kbuf->image->control_pages)) {

  		WARN_ON(1);
  		return -EINVAL;
  	}

  	/* Ensure minimum alignment needed for segments. */
  	kbuf->memsz = ALIGN(kbuf->memsz, PAGE_SIZE);
  	kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE);

  
  	/* Walk the RAM ranges and allocate a suitable range for the buffer */

  	ret = kexec_locate_mem_hole(kbuf);
  	if (ret)
  		return ret;

  
  	/* Found a suitable memory range */

  	ksegment = &kbuf->image->segment[kbuf->image->nr_segments];

  	ksegment->kbuf = kbuf->buffer;
  	ksegment->bufsz = kbuf->bufsz;
  	ksegment->mem = kbuf->mem;
  	ksegment->memsz = kbuf->memsz;

  	kbuf->image->nr_segments++;

  	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;

  	if (!IS_ENABLED(CONFIG_ARCH_HAS_KEXEC_PURGATORY))
  		return 0;

  	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;

  
  	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, "purgatory_sha_regions",
  						     sha_regions, sha_region_sz, 0);

  		if (ret)
  			goto out_free_digest;

  		ret = kexec_purgatory_get_set_symbol(image, "purgatory_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;
  }

  #ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY

  /*
   * kexec_purgatory_setup_kbuf - prepare buffer to load purgatory.
   * @pi:		Purgatory to be loaded.
   * @kbuf:	Buffer to setup.
   *
   * Allocates the memory needed for the buffer. Caller is responsible to free
   * the memory after use.
   *
   * Return: 0 on success, negative errno on error.
   */
  static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
  				      struct kexec_buf *kbuf)

  {

  	const Elf_Shdr *sechdrs;
  	unsigned long bss_align;
  	unsigned long bss_sz;
  	unsigned long align;
  	int i, ret;

  	sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;

  	kbuf->buf_align = bss_align = 1;
  	kbuf->bufsz = 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 (kbuf->buf_align < align)
  				kbuf->buf_align = align;
  			kbuf->bufsz = ALIGN(kbuf->bufsz, align);
  			kbuf->bufsz += sechdrs[i].sh_size;
  		} else {
  			if (bss_align < align)
  				bss_align = align;
  			bss_sz = ALIGN(bss_sz, align);
  			bss_sz += sechdrs[i].sh_size;
  		}
  	}
  	kbuf->bufsz = ALIGN(kbuf->bufsz, bss_align);
  	kbuf->memsz = kbuf->bufsz + bss_sz;
  	if (kbuf->buf_align < bss_align)
  		kbuf->buf_align = bss_align;
  
  	kbuf->buffer = vzalloc(kbuf->bufsz);
  	if (!kbuf->buffer)
  		return -ENOMEM;
  	pi->purgatory_buf = kbuf->buffer;
  
  	ret = kexec_add_buffer(kbuf);
  	if (ret)
  		goto out;

  
  	return 0;
  out:
  	vfree(pi->purgatory_buf);
  	pi->purgatory_buf = NULL;
  	return ret;
  }
  
  /*
   * kexec_purgatory_setup_sechdrs - prepares the pi->sechdrs buffer.
   * @pi:		Purgatory to be loaded.
   * @kbuf:	Buffer prepared to store purgatory.
   *
   * Allocates the memory needed for the buffer. Caller is responsible to free
   * the memory after use.
   *
   * Return: 0 on success, negative errno on error.
   */
  static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
  					 struct kexec_buf *kbuf)
  {

  	unsigned long bss_addr;
  	unsigned long offset;

  	Elf_Shdr *sechdrs;

  	int i;

  	/*
  	 * The section headers in kexec_purgatory are read-only. In order to
  	 * have them modifiable make a temporary copy.
  	 */

  	sechdrs = vzalloc(array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum));

  	if (!sechdrs)
  		return -ENOMEM;

  	memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff,
  	       pi->ehdr->e_shnum * sizeof(Elf_Shdr));
  	pi->sechdrs = sechdrs;

  	offset = 0;
  	bss_addr = kbuf->mem + kbuf->bufsz;

  	kbuf->image->start = pi->ehdr->e_entry;

  
  	for (i = 0; i < pi->ehdr->e_shnum; i++) {

  		unsigned long align;

  		void *src, *dst;

  		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
  			continue;
  
  		align = sechdrs[i].sh_addralign;

  		if (sechdrs[i].sh_type == SHT_NOBITS) {

  			bss_addr = ALIGN(bss_addr, align);
  			sechdrs[i].sh_addr = bss_addr;
  			bss_addr += sechdrs[i].sh_size;

  			continue;
  		}

  		offset = ALIGN(offset, align);

  		if (sechdrs[i].sh_flags & SHF_EXECINSTR &&
  		    pi->ehdr->e_entry >= sechdrs[i].sh_addr &&
  		    pi->ehdr->e_entry < (sechdrs[i].sh_addr
  					 + sechdrs[i].sh_size)) {
  			kbuf->image->start -= sechdrs[i].sh_addr;

  			kbuf->image->start += kbuf->mem + offset;

  		}

  		src = (void *)pi->ehdr + sechdrs[i].sh_offset;

  		dst = pi->purgatory_buf + offset;
  		memcpy(dst, src, sechdrs[i].sh_size);
  
  		sechdrs[i].sh_addr = kbuf->mem + offset;

  		sechdrs[i].sh_offset = offset;

  		offset += sechdrs[i].sh_size;

  	}

  	return 0;

  }
  
  static int kexec_apply_relocations(struct kimage *image)
  {
  	int i, ret;
  	struct purgatory_info *pi = &image->purgatory_info;

  	const Elf_Shdr *sechdrs;
  
  	sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;

  	for (i = 0; i < pi->ehdr->e_shnum; i++) {

  		const Elf_Shdr *relsec;
  		const Elf_Shdr *symtab;
  		Elf_Shdr *section;
  
  		relsec = sechdrs + i;

  		if (relsec->sh_type != SHT_RELA &&
  		    relsec->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 (relsec->sh_info >= pi->ehdr->e_shnum ||
  		    relsec->sh_link >= pi->ehdr->e_shnum)

  			return -ENOEXEC;

  		section = pi->sechdrs + relsec->sh_info;
  		symtab = sechdrs + relsec->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 (relsec->sh_type == SHT_RELA)
  			ret = arch_kexec_apply_relocations_add(pi, section,
  							       relsec, symtab);
  		else if (relsec->sh_type == SHT_REL)
  			ret = arch_kexec_apply_relocations(pi, section,
  							   relsec, symtab);

  		if (ret)
  			return ret;
  	}
  
  	return 0;
  }

  /*
   * kexec_load_purgatory - Load and relocate the purgatory object.
   * @image:	Image to add the purgatory to.
   * @kbuf:	Memory parameters to use.
   *
   * Allocates the memory needed for image->purgatory_info.sechdrs and
   * image->purgatory_info.purgatory_buf/kbuf->buffer. Caller is responsible
   * to free the memory after use.
   *
   * Return: 0 on success, negative errno on error.
   */
  int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf)

  {
  	struct purgatory_info *pi = &image->purgatory_info;
  	int ret;
  
  	if (kexec_purgatory_size <= 0)
  		return -EINVAL;

  	pi->ehdr = (const Elf_Ehdr *)kexec_purgatory;

  	ret = kexec_purgatory_setup_kbuf(pi, kbuf);

  	if (ret)
  		return ret;

  	ret = kexec_purgatory_setup_sechdrs(pi, kbuf);

  	if (ret)
  		goto out_free_kbuf;

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

  	return 0;
  out:
  	vfree(pi->sechdrs);

  	pi->sechdrs = NULL;

  out_free_kbuf:

  	vfree(pi->purgatory_buf);

  	pi->purgatory_buf = NULL;

  	return ret;
  }

  /*
   * kexec_purgatory_find_symbol - find a symbol in the purgatory
   * @pi:		Purgatory to search in.
   * @name:	Name of the symbol.
   *
   * Return: pointer to symbol in read-only symtab on success, NULL on error.
   */
  static const Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
  						  const char *name)

  {

  	const Elf_Shdr *sechdrs;

  	const Elf_Ehdr *ehdr;

  	const Elf_Sym *syms;

  	const char *strtab;

  	int i, k;

  	if (!pi->ehdr)

  		return NULL;

  	ehdr = pi->ehdr;

  	sechdrs = (void *)ehdr + ehdr->e_shoff;

  
  	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 = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset;
  		syms = (void *)ehdr + 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;

  	const 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)
  {

  	struct purgatory_info *pi = &image->purgatory_info;

  	const Elf_Sym *sym;
  	Elf_Shdr *sec;

  	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;
  	}

  	sec = pi->sechdrs + sym->st_shndx;

  	if (sec->sh_type == SHT_NOBITS) {

  		pr_err("symbol %s is in a bss section. Cannot %s
  ", name,
  		       get_value ? "get" : "set");
  		return -EINVAL;
  	}

  	sym_buf = (char *)pi->purgatory_buf + sec->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_ARCH_HAS_KEXEC_PURGATORY */

  
  int crash_exclude_mem_range(struct crash_mem *mem,
  			    unsigned long long mstart, unsigned long long mend)
  {
  	int i, j;
  	unsigned long long start, end;
  	struct crash_mem_range temp_range = {0, 0};
  
  	for (i = 0; i < mem->nr_ranges; i++) {
  		start = mem->ranges[i].start;
  		end = mem->ranges[i].end;
  
  		if (mstart > end || mend < start)
  			continue;
  
  		/* Truncate any area outside of range */
  		if (mstart < start)
  			mstart = start;
  		if (mend > end)
  			mend = end;
  
  		/* Found completely overlapping range */
  		if (mstart == start && mend == end) {
  			mem->ranges[i].start = 0;
  			mem->ranges[i].end = 0;
  			if (i < mem->nr_ranges - 1) {
  				/* Shift rest of the ranges to left */
  				for (j = i; j < mem->nr_ranges - 1; j++) {
  					mem->ranges[j].start =
  						mem->ranges[j+1].start;
  					mem->ranges[j].end =
  							mem->ranges[j+1].end;
  				}
  			}
  			mem->nr_ranges--;
  			return 0;
  		}
  
  		if (mstart > start && mend < end) {
  			/* Split original range */
  			mem->ranges[i].end = mstart - 1;
  			temp_range.start = mend + 1;
  			temp_range.end = end;
  		} else if (mstart != start)
  			mem->ranges[i].end = mstart - 1;
  		else
  			mem->ranges[i].start = mend + 1;
  		break;
  	}
  
  	/* If a split happened, add the split to array */
  	if (!temp_range.end)
  		return 0;
  
  	/* Split happened */
  	if (i == mem->max_nr_ranges - 1)
  		return -ENOMEM;
  
  	/* Location where new range should go */
  	j = i + 1;
  	if (j < mem->nr_ranges) {
  		/* Move over all ranges one slot towards the end */
  		for (i = mem->nr_ranges - 1; i >= j; i--)
  			mem->ranges[i + 1] = mem->ranges[i];
  	}
  
  	mem->ranges[j].start = temp_range.start;
  	mem->ranges[j].end = temp_range.end;
  	mem->nr_ranges++;
  	return 0;
  }
  
  int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
  			  void **addr, unsigned long *sz)
  {
  	Elf64_Ehdr *ehdr;
  	Elf64_Phdr *phdr;
  	unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;
  	unsigned char *buf;
  	unsigned int cpu, i;
  	unsigned long long notes_addr;
  	unsigned long mstart, mend;
  
  	/* extra phdr for vmcoreinfo elf note */
  	nr_phdr = nr_cpus + 1;
  	nr_phdr += mem->nr_ranges;
  
  	/*
  	 * kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
  	 * area (for example, ffffffff80000000 - ffffffffa0000000 on x86_64).
  	 * I think this is required by tools like gdb. So same physical
  	 * memory will be mapped in two elf headers. One will contain kernel
  	 * text virtual addresses and other will have __va(physical) addresses.
  	 */
  
  	nr_phdr++;
  	elf_sz = sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr);
  	elf_sz = ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN);
  
  	buf = vzalloc(elf_sz);
  	if (!buf)
  		return -ENOMEM;
  
  	ehdr = (Elf64_Ehdr *)buf;
  	phdr = (Elf64_Phdr *)(ehdr + 1);
  	memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
  	ehdr->e_ident[EI_CLASS] = ELFCLASS64;
  	ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
  	ehdr->e_ident[EI_VERSION] = EV_CURRENT;
  	ehdr->e_ident[EI_OSABI] = ELF_OSABI;
  	memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
  	ehdr->e_type = ET_CORE;
  	ehdr->e_machine = ELF_ARCH;
  	ehdr->e_version = EV_CURRENT;
  	ehdr->e_phoff = sizeof(Elf64_Ehdr);
  	ehdr->e_ehsize = sizeof(Elf64_Ehdr);
  	ehdr->e_phentsize = sizeof(Elf64_Phdr);
  
  	/* Prepare one phdr of type PT_NOTE for each present cpu */
  	for_each_present_cpu(cpu) {
  		phdr->p_type = PT_NOTE;
  		notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
  		phdr->p_offset = phdr->p_paddr = notes_addr;
  		phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);
  		(ehdr->e_phnum)++;
  		phdr++;
  	}
  
  	/* Prepare one PT_NOTE header for vmcoreinfo */
  	phdr->p_type = PT_NOTE;
  	phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
  	phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE;
  	(ehdr->e_phnum)++;
  	phdr++;
  
  	/* Prepare PT_LOAD type program header for kernel text region */
  	if (kernel_map) {
  		phdr->p_type = PT_LOAD;
  		phdr->p_flags = PF_R|PF_W|PF_X;
  		phdr->p_vaddr = (Elf64_Addr)_text;
  		phdr->p_filesz = phdr->p_memsz = _end - _text;
  		phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
  		ehdr->e_phnum++;
  		phdr++;
  	}
  
  	/* Go through all the ranges in mem->ranges[] and prepare phdr */
  	for (i = 0; i < mem->nr_ranges; i++) {
  		mstart = mem->ranges[i].start;
  		mend = mem->ranges[i].end;
  
  		phdr->p_type = PT_LOAD;
  		phdr->p_flags = PF_R|PF_W|PF_X;
  		phdr->p_offset  = mstart;
  
  		phdr->p_paddr = mstart;
  		phdr->p_vaddr = (unsigned long long) __va(mstart);
  		phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
  		phdr->p_align = 0;
  		ehdr->e_phnum++;
  		phdr++;
  		pr_debug("Crash PT_LOAD elf header. phdr=%p vaddr=0x%llx, paddr=0x%llx, sz=0x%llx e_phnum=%d p_offset=0x%llx
  ",
  			phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz,
  			ehdr->e_phnum, phdr->p_offset);
  	}
  
  	*addr = buf;
  	*sz = elf_sz;
  	return 0;
  }