text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   *	fs/proc/vmcore.c Interface for accessing the crash
   * 				 dump from the system's previous life.
   * 	Heavily borrowed from fs/proc/kcore.c
   *	Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
   *	Copyright (C) IBM Corporation, 2004. All rights reserved
   *
   */
  
  #include <linux/mm.h>
  #include <linux/kcore.h>
  #include <linux/user.h>
  #include <linux/elf.h>
  #include <linux/elfcore.h>
  #include <linux/export.h>
  #include <linux/slab.h>
  #include <linux/highmem.h>
  #include <linux/printk.h>
  #include <linux/memblock.h>
  #include <linux/init.h>
  #include <linux/crash_dump.h>
  #include <linux/list.h>
  #include <linux/moduleparam.h>
  #include <linux/mutex.h>
  #include <linux/vmalloc.h>
  #include <linux/pagemap.h>
  #include <linux/uaccess.h>
  #include <linux/cc_platform.h>
  #include <asm/io.h>
  #include "internal.h"
  
  /* List representing chunks of contiguous memory areas and their offsets in
   * vmcore file.
   */
  static LIST_HEAD(vmcore_list);
  
  /* Stores the pointer to the buffer containing kernel elf core headers. */
  static char *elfcorebuf;
  static size_t elfcorebuf_sz;
  static size_t elfcorebuf_sz_orig;
  
  static char *elfnotes_buf;
  static size_t elfnotes_sz;
  /* Size of all notes minus the device dump notes */
  static size_t elfnotes_orig_sz;
  
  /* Total size of vmcore file. */
  static u64 vmcore_size;
  
  static struct proc_dir_entry *proc_vmcore;
  
  #ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
  /* Device Dump list and mutex to synchronize access to list */
  static LIST_HEAD(vmcoredd_list);
  static DEFINE_MUTEX(vmcoredd_mutex);
  
  static bool vmcoredd_disabled;
  core_param(novmcoredd, vmcoredd_disabled, bool, 0);
  #endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */
  
  /* Device Dump Size */
  static size_t vmcoredd_orig_sz;
  
  /*
   * Returns > 0 for RAM pages, 0 for non-RAM pages, < 0 on error
   * The called function has to take care of module refcounting.
   */
  static int (*oldmem_pfn_is_ram)(unsigned long pfn);
  
  int register_oldmem_pfn_is_ram(int (*fn)(unsigned long pfn))
  {
  	if (oldmem_pfn_is_ram)
  		return -EBUSY;
  	oldmem_pfn_is_ram = fn;
  	return 0;
  }
  EXPORT_SYMBOL_GPL(register_oldmem_pfn_is_ram);
  
  void unregister_oldmem_pfn_is_ram(void)
  {
  	oldmem_pfn_is_ram = NULL;
  	wmb();
  }
  EXPORT_SYMBOL_GPL(unregister_oldmem_pfn_is_ram);
  
  static int pfn_is_ram(unsigned long pfn)
  {
  	int (*fn)(unsigned long pfn);
  	/* pfn is ram unless fn() checks pagetype */
  	int ret = 1;
  
  	/*
  	 * Ask hypervisor if the pfn is really ram.
  	 * A ballooned page contains no data and reading from such a page
  	 * will cause high load in the hypervisor.
  	 */
  	fn = oldmem_pfn_is_ram;
  	if (fn)
  		ret = fn(pfn);
  
  	return ret;
  }
  
  /* Reads a page from the oldmem device from given offset. */
  ssize_t read_from_oldmem(char *buf, size_t count,
  			 u64 *ppos, int userbuf,
  			 bool encrypted)
  {
  	unsigned long pfn, offset;
  	size_t nr_bytes;
  	ssize_t read = 0, tmp;
  
  	if (!count)
  		return 0;
  
  	offset = (unsigned long)(*ppos % PAGE_SIZE);
  	pfn = (unsigned long)(*ppos / PAGE_SIZE);
  
  	do {
  		if (count > (PAGE_SIZE - offset))
  			nr_bytes = PAGE_SIZE - offset;
  		else
  			nr_bytes = count;
  
  		/* If pfn is not ram, return zeros for sparse dump files */
  		if (pfn_is_ram(pfn) == 0)
  			memset(buf, 0, nr_bytes);
  		else {
  			if (encrypted)
  				tmp = copy_oldmem_page_encrypted(pfn, buf,
  								 nr_bytes,
  								 offset,
  								 userbuf);
  			else
  				tmp = copy_oldmem_page(pfn, buf, nr_bytes,
  						       offset, userbuf);
  
  			if (tmp < 0)
  				return tmp;
  		}
  		*ppos += nr_bytes;
  		count -= nr_bytes;
  		buf += nr_bytes;
  		read += nr_bytes;
  		++pfn;
  		offset = 0;
  	} while (count);
  
  	return read;
  }
  
  /*
   * Architectures may override this function to allocate ELF header in 2nd kernel
   */
  int __weak elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size)
  {
  	return 0;
  }
  
  /*
   * Architectures may override this function to free header
   */
  void __weak elfcorehdr_free(unsigned long long addr)
  {}
  
  /*
   * Architectures may override this function to read from ELF header
   */
  ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos)
  {
  	return read_from_oldmem(buf, count, ppos, 0, false);
  }
  
  /*
   * Architectures may override this function to read from notes sections
   */
  ssize_t __weak elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos)
  {
  	return read_from_oldmem(buf, count, ppos, 0, cc_platform_has(CC_ATTR_MEM_ENCRYPT));
  }
  
  /*
   * Architectures may override this function to map oldmem
   */
  int __weak remap_oldmem_pfn_range(struct vm_area_struct *vma,
  				  unsigned long from, unsigned long pfn,
  				  unsigned long size, pgprot_t prot)
  {
  	prot = pgprot_encrypted(prot);
  	return remap_pfn_range(vma, from, pfn, size, prot);
  }
  
  /*
   * Architectures which support memory encryption override this.
   */
  ssize_t __weak
  copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
  			   unsigned long offset, int userbuf)
  {
  	return copy_oldmem_page(pfn, buf, csize, offset, userbuf);
  }
  
  /*
   * Copy to either kernel or user space
   */
  static int copy_to(void *target, void *src, size_t size, int userbuf)
  {
  	if (userbuf) {
  		if (copy_to_user((char __user *) target, src, size))
  			return -EFAULT;
  	} else {
  		memcpy(target, src, size);
  	}
  	return 0;
  }
  
  #ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
  static int vmcoredd_copy_dumps(void *dst, u64 start, size_t size, int userbuf)
  {
  	struct vmcoredd_node *dump;
  	u64 offset = 0;
  	int ret = 0;
  	size_t tsz;
  	char *buf;
  
  	mutex_lock(&vmcoredd_mutex);
  	list_for_each_entry(dump, &vmcoredd_list, list) {
  		if (start < offset + dump->size) {
  			tsz = min(offset + (u64)dump->size - start, (u64)size);
  			buf = dump->buf + start - offset;
  			if (copy_to(dst, buf, tsz, userbuf)) {
  				ret = -EFAULT;
  				goto out_unlock;
  			}
  
  			size -= tsz;
  			start += tsz;
  			dst += tsz;
  
  			/* Leave now if buffer filled already */
  			if (!size)
  				goto out_unlock;
  		}
  		offset += dump->size;
  	}
  
  out_unlock:
  	mutex_unlock(&vmcoredd_mutex);
  	return ret;
  }
  
  #ifdef CONFIG_MMU
  static int vmcoredd_mmap_dumps(struct vm_area_struct *vma, unsigned long dst,
  			       u64 start, size_t size)
  {
  	struct vmcoredd_node *dump;
  	u64 offset = 0;
  	int ret = 0;
  	size_t tsz;
  	char *buf;
  
  	mutex_lock(&vmcoredd_mutex);
  	list_for_each_entry(dump, &vmcoredd_list, list) {
  		if (start < offset + dump->size) {
  			tsz = min(offset + (u64)dump->size - start, (u64)size);
  			buf = dump->buf + start - offset;
  			if (remap_vmalloc_range_partial(vma, dst, buf, 0,
  							tsz)) {
  				ret = -EFAULT;
  				goto out_unlock;
  			}
  
  			size -= tsz;
  			start += tsz;
  			dst += tsz;
  
  			/* Leave now if buffer filled already */
  			if (!size)
  				goto out_unlock;
  		}
  		offset += dump->size;
  	}
  
  out_unlock:
  	mutex_unlock(&vmcoredd_mutex);
  	return ret;
  }
  #endif /* CONFIG_MMU */
  #endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */
  
  /* Read from the ELF header and then the crash dump. On error, negative value is
   * returned otherwise number of bytes read are returned.
   */
  static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos,
  			     int userbuf)
  {
  	ssize_t acc = 0, tmp;
  	size_t tsz;
  	u64 start;
  	struct vmcore *m = NULL;
  
  	if (buflen == 0 || *fpos >= vmcore_size)
  		return 0;
  
  	/* trim buflen to not go beyond EOF */
  	if (buflen > vmcore_size - *fpos)
  		buflen = vmcore_size - *fpos;
  
  	/* Read ELF core header */
  	if (*fpos < elfcorebuf_sz) {
  		tsz = min(elfcorebuf_sz - (size_t)*fpos, buflen);
  		if (copy_to(buffer, elfcorebuf + *fpos, tsz, userbuf))
  			return -EFAULT;
  		buflen -= tsz;
  		*fpos += tsz;
  		buffer += tsz;
  		acc += tsz;
  
  		/* leave now if filled buffer already */
  		if (buflen == 0)
  			return acc;
  	}
  
  	/* Read Elf note segment */
  	if (*fpos < elfcorebuf_sz + elfnotes_sz) {
  		void *kaddr;
  
  		/* We add device dumps before other elf notes because the
  		 * other elf notes may not fill the elf notes buffer
  		 * completely and we will end up with zero-filled data
  		 * between the elf notes and the device dumps. Tools will
  		 * then try to decode this zero-filled data as valid notes
  		 * and we don't want that. Hence, adding device dumps before
  		 * the other elf notes ensure that zero-filled data can be
  		 * avoided.
  		 */
  #ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
  		/* Read device dumps */
  		if (*fpos < elfcorebuf_sz + vmcoredd_orig_sz) {
  			tsz = min(elfcorebuf_sz + vmcoredd_orig_sz -
  				  (size_t)*fpos, buflen);
  			start = *fpos - elfcorebuf_sz;
  			if (vmcoredd_copy_dumps(buffer, start, tsz, userbuf))
  				return -EFAULT;
  
  			buflen -= tsz;
  			*fpos += tsz;
  			buffer += tsz;
  			acc += tsz;
  
  			/* leave now if filled buffer already */
  			if (!buflen)
  				return acc;
  		}
  #endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */
  
  		/* Read remaining elf notes */
  		tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)*fpos, buflen);
  		kaddr = elfnotes_buf + *fpos - elfcorebuf_sz - vmcoredd_orig_sz;
  		if (copy_to(buffer, kaddr, tsz, userbuf))
  			return -EFAULT;
  
  		buflen -= tsz;
  		*fpos += tsz;
  		buffer += tsz;
  		acc += tsz;
  
  		/* leave now if filled buffer already */
  		if (buflen == 0)
  			return acc;
  	}
  
  	list_for_each_entry(m, &vmcore_list, list) {
  		if (*fpos < m->offset + m->size) {
  			tsz = (size_t)min_t(unsigned long long,
  					    m->offset + m->size - *fpos,
  					    buflen);
  			start = m->paddr + *fpos - m->offset;
  			tmp = read_from_oldmem(buffer, tsz, &start,
  					       userbuf, cc_platform_has(CC_ATTR_MEM_ENCRYPT));
  			if (tmp < 0)
  				return tmp;
  			buflen -= tsz;
  			*fpos += tsz;
  			buffer += tsz;
  			acc += tsz;
  
  			/* leave now if filled buffer already */
  			if (buflen == 0)
  				return acc;
  		}
  	}
  
  	return acc;
  }
  
  static ssize_t read_vmcore(struct file *file, char __user *buffer,
  			   size_t buflen, loff_t *fpos)
  {
  	return __read_vmcore((__force char *) buffer, buflen, fpos, 1);
  }
  
  /*
   * The vmcore fault handler uses the page cache and fills data using the
   * standard __vmcore_read() function.
   *
   * On s390 the fault handler is used for memory regions that can't be mapped
   * directly with remap_pfn_range().
   */
  static vm_fault_t mmap_vmcore_fault(struct vm_fault *vmf)
  {
  #ifdef CONFIG_S390
  	struct address_space *mapping = vmf->vma->vm_file->f_mapping;
  	pgoff_t index = vmf->pgoff;
  	struct page *page;
  	loff_t offset;
  	char *buf;
  	int rc;
  
  	page = find_or_create_page(mapping, index, GFP_KERNEL);
  	if (!page)
  		return VM_FAULT_OOM;
  	if (!PageUptodate(page)) {
  		offset = (loff_t) index << PAGE_SHIFT;
  		buf = __va((page_to_pfn(page) << PAGE_SHIFT));
  		rc = __read_vmcore(buf, PAGE_SIZE, &offset, 0);
  		if (rc < 0) {
  			unlock_page(page);
  			put_page(page);
  			return vmf_error(rc);
  		}
  		SetPageUptodate(page);
  	}
  	unlock_page(page);
  	vmf->page = page;
  	return 0;
  #else
  	return VM_FAULT_SIGBUS;
  #endif
  }
  
  static const struct vm_operations_struct vmcore_mmap_ops = {
  	.fault = mmap_vmcore_fault,
  };
  
  /**
   * vmcore_alloc_buf - allocate buffer in vmalloc memory
   * @sizez: size of buffer
   *
   * If CONFIG_MMU is defined, use vmalloc_user() to allow users to mmap
   * the buffer to user-space by means of remap_vmalloc_range().
   *
   * If CONFIG_MMU is not defined, use vzalloc() since mmap_vmcore() is
   * disabled and there's no need to allow users to mmap the buffer.
   */
  static inline char *vmcore_alloc_buf(size_t size)
  {
  #ifdef CONFIG_MMU
  	return vmalloc_user(size);
  #else
  	return vzalloc(size);
  #endif
  }
  
  /*
   * Disable mmap_vmcore() if CONFIG_MMU is not defined. MMU is
   * essential for mmap_vmcore() in order to map physically
   * non-contiguous objects (ELF header, ELF note segment and memory
   * regions in the 1st kernel pointed to by PT_LOAD entries) into
   * virtually contiguous user-space in ELF layout.
   */
  #ifdef CONFIG_MMU
  /*
   * remap_oldmem_pfn_checked - do remap_oldmem_pfn_range replacing all pages
   * reported as not being ram with the zero page.
   *
   * @vma: vm_area_struct describing requested mapping
   * @from: start remapping from
   * @pfn: page frame number to start remapping to
   * @size: remapping size
   * @prot: protection bits
   *
   * Returns zero on success, -EAGAIN on failure.
   */
  static int remap_oldmem_pfn_checked(struct vm_area_struct *vma,
  				    unsigned long from, unsigned long pfn,
  				    unsigned long size, pgprot_t prot)
  {
  	unsigned long map_size;
  	unsigned long pos_start, pos_end, pos;
  	unsigned long zeropage_pfn = my_zero_pfn(0);
  	size_t len = 0;
  
  	pos_start = pfn;
  	pos_end = pfn + (size >> PAGE_SHIFT);
  
  	for (pos = pos_start; pos < pos_end; ++pos) {
  		if (!pfn_is_ram(pos)) {
  			/*
  			 * We hit a page which is not ram. Remap the continuous
  			 * region between pos_start and pos-1 and replace
  			 * the non-ram page at pos with the zero page.
  			 */
  			if (pos > pos_start) {
  				/* Remap continuous region */
  				map_size = (pos - pos_start) << PAGE_SHIFT;
  				if (remap_oldmem_pfn_range(vma, from + len,
  							   pos_start, map_size,
  							   prot))
  					goto fail;
  				len += map_size;
  			}
  			/* Remap the zero page */
  			if (remap_oldmem_pfn_range(vma, from + len,
  						   zeropage_pfn,
  						   PAGE_SIZE, prot))
  				goto fail;
  			len += PAGE_SIZE;
  			pos_start = pos + 1;
  		}
  	}
  	if (pos > pos_start) {
  		/* Remap the rest */
  		map_size = (pos - pos_start) << PAGE_SHIFT;
  		if (remap_oldmem_pfn_range(vma, from + len, pos_start,
  					   map_size, prot))
  			goto fail;
  	}
  	return 0;
  fail:
  	do_munmap(vma->vm_mm, from, len, NULL);
  	return -EAGAIN;
  }
  
  static int vmcore_remap_oldmem_pfn(struct vm_area_struct *vma,
  			    unsigned long from, unsigned long pfn,
  			    unsigned long size, pgprot_t prot)
  {
  	/*
  	 * Check if oldmem_pfn_is_ram was registered to avoid
  	 * looping over all pages without a reason.
  	 */
  	if (oldmem_pfn_is_ram)
  		return remap_oldmem_pfn_checked(vma, from, pfn, size, prot);
  	else
  		return remap_oldmem_pfn_range(vma, from, pfn, size, prot);
  }
  
  static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
  {
  	size_t size = vma->vm_end - vma->vm_start;
  	u64 start, end, len, tsz;
  	struct vmcore *m;
  
  	start = (u64)vma->vm_pgoff << PAGE_SHIFT;
  	end = start + size;
  
  	if (size > vmcore_size || end > vmcore_size)
  		return -EINVAL;
  
  	if (vma->vm_flags & (VM_WRITE | VM_EXEC))
  		return -EPERM;
  
  	vma->vm_flags &= ~(VM_MAYWRITE | VM_MAYEXEC);
  	vma->vm_flags |= VM_MIXEDMAP;
  	vma->vm_ops = &vmcore_mmap_ops;
  
  	len = 0;
  
  	if (start < elfcorebuf_sz) {
  		u64 pfn;
  
  		tsz = min(elfcorebuf_sz - (size_t)start, size);
  		pfn = __pa(elfcorebuf + start) >> PAGE_SHIFT;
  		if (remap_pfn_range(vma, vma->vm_start, pfn, tsz,
  				    vma->vm_page_prot))
  			return -EAGAIN;
  		size -= tsz;
  		start += tsz;
  		len += tsz;
  
  		if (size == 0)
  			return 0;
  	}
  
  	if (start < elfcorebuf_sz + elfnotes_sz) {
  		void *kaddr;
  
  		/* We add device dumps before other elf notes because the
  		 * other elf notes may not fill the elf notes buffer
  		 * completely and we will end up with zero-filled data
  		 * between the elf notes and the device dumps. Tools will
  		 * then try to decode this zero-filled data as valid notes
  		 * and we don't want that. Hence, adding device dumps before
  		 * the other elf notes ensure that zero-filled data can be
  		 * avoided. This also ensures that the device dumps and
  		 * other elf notes can be properly mmaped at page aligned
  		 * address.
  		 */
  #ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
  		/* Read device dumps */
  		if (start < elfcorebuf_sz + vmcoredd_orig_sz) {
  			u64 start_off;
  
  			tsz = min(elfcorebuf_sz + vmcoredd_orig_sz -
  				  (size_t)start, size);
  			start_off = start - elfcorebuf_sz;
  			if (vmcoredd_mmap_dumps(vma, vma->vm_start + len,
  						start_off, tsz))
  				goto fail;
  
  			size -= tsz;
  			start += tsz;
  			len += tsz;
  
  			/* leave now if filled buffer already */
  			if (!size)
  				return 0;
  		}
  #endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */
  
  		/* Read remaining elf notes */
  		tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)start, size);
  		kaddr = elfnotes_buf + start - elfcorebuf_sz - vmcoredd_orig_sz;
  		if (remap_vmalloc_range_partial(vma, vma->vm_start + len,
  						kaddr, 0, tsz))
  			goto fail;
  
  		size -= tsz;
  		start += tsz;
  		len += tsz;
  
  		if (size == 0)
  			return 0;
  	}
  
  	list_for_each_entry(m, &vmcore_list, list) {
  		if (start < m->offset + m->size) {
  			u64 paddr = 0;
  
  			tsz = (size_t)min_t(unsigned long long,
  					    m->offset + m->size - start, size);
  			paddr = m->paddr + start - m->offset;
  			if (vmcore_remap_oldmem_pfn(vma, vma->vm_start + len,
  						    paddr >> PAGE_SHIFT, tsz,
  						    vma->vm_page_prot))
  				goto fail;
  			size -= tsz;
  			start += tsz;
  			len += tsz;
  
  			if (size == 0)
  				return 0;
  		}
  	}
  
  	return 0;
  fail:
  	do_munmap(vma->vm_mm, vma->vm_start, len, NULL);
  	return -EAGAIN;
  }
  #else
  static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
  {
  	return -ENOSYS;
  }
  #endif
  
  static const struct proc_ops vmcore_proc_ops = {
  	.proc_read	= read_vmcore,
  	.proc_lseek	= default_llseek,
  	.proc_mmap	= mmap_vmcore,
  };
  
  static struct vmcore* __init get_new_element(void)
  {
  	return kzalloc(sizeof(struct vmcore), GFP_KERNEL);
  }
  
  static u64 get_vmcore_size(size_t elfsz, size_t elfnotesegsz,
  			   struct list_head *vc_list)
  {
  	u64 size;
  	struct vmcore *m;
  
  	size = elfsz + elfnotesegsz;
  	list_for_each_entry(m, vc_list, list) {
  		size += m->size;
  	}
  	return size;
  }
  
  /**
   * update_note_header_size_elf64 - update p_memsz member of each PT_NOTE entry
   *
   * @ehdr_ptr: ELF header
   *
   * This function updates p_memsz member of each PT_NOTE entry in the
   * program header table pointed to by @ehdr_ptr to real size of ELF
   * note segment.
   */
  static int __init update_note_header_size_elf64(const Elf64_Ehdr *ehdr_ptr)
  {
  	int i, rc=0;
  	Elf64_Phdr *phdr_ptr;
  	Elf64_Nhdr *nhdr_ptr;
  
  	phdr_ptr = (Elf64_Phdr *)(ehdr_ptr + 1);
  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
  		void *notes_section;
  		u64 offset, max_sz, sz, real_sz = 0;
  		if (phdr_ptr->p_type != PT_NOTE)
  			continue;
  		max_sz = phdr_ptr->p_memsz;
  		offset = phdr_ptr->p_offset;
  		notes_section = kmalloc(max_sz, GFP_KERNEL);
  		if (!notes_section)
  			return -ENOMEM;
  		rc = elfcorehdr_read_notes(notes_section, max_sz, &offset);
  		if (rc < 0) {
  			kfree(notes_section);
  			return rc;
  		}
  		nhdr_ptr = notes_section;
  		while (nhdr_ptr->n_namesz != 0) {
  			sz = sizeof(Elf64_Nhdr) +
  				(((u64)nhdr_ptr->n_namesz + 3) & ~3) +
  				(((u64)nhdr_ptr->n_descsz + 3) & ~3);
  			if ((real_sz + sz) > max_sz) {
  				pr_warn("Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n",
  					nhdr_ptr->n_namesz, nhdr_ptr->n_descsz);
  				break;
  			}
  			real_sz += sz;
  			nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz);
  		}
  		kfree(notes_section);
  		phdr_ptr->p_memsz = real_sz;
  		if (real_sz == 0) {
  			pr_warn("Warning: Zero PT_NOTE entries found\n");
  		}
  	}
  
  	return 0;
  }
  
  /**
   * get_note_number_and_size_elf64 - get the number of PT_NOTE program
   * headers and sum of real size of their ELF note segment headers and
   * data.
   *
   * @ehdr_ptr: ELF header
   * @nr_ptnote: buffer for the number of PT_NOTE program headers
   * @sz_ptnote: buffer for size of unique PT_NOTE program header
   *
   * This function is used to merge multiple PT_NOTE program headers
   * into a unique single one. The resulting unique entry will have
   * @sz_ptnote in its phdr->p_mem.
   *
   * It is assumed that program headers with PT_NOTE type pointed to by
   * @ehdr_ptr has already been updated by update_note_header_size_elf64
   * and each of PT_NOTE program headers has actual ELF note segment
   * size in its p_memsz member.
   */
  static int __init get_note_number_and_size_elf64(const Elf64_Ehdr *ehdr_ptr,
  						 int *nr_ptnote, u64 *sz_ptnote)
  {
  	int i;
  	Elf64_Phdr *phdr_ptr;
  
  	*nr_ptnote = *sz_ptnote = 0;
  
  	phdr_ptr = (Elf64_Phdr *)(ehdr_ptr + 1);
  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
  		if (phdr_ptr->p_type != PT_NOTE)
  			continue;
  		*nr_ptnote += 1;
  		*sz_ptnote += phdr_ptr->p_memsz;
  	}
  
  	return 0;
  }
  
  /**
   * copy_notes_elf64 - copy ELF note segments in a given buffer
   *
   * @ehdr_ptr: ELF header
   * @notes_buf: buffer into which ELF note segments are copied
   *
   * This function is used to copy ELF note segment in the 1st kernel
   * into the buffer @notes_buf in the 2nd kernel. It is assumed that
   * size of the buffer @notes_buf is equal to or larger than sum of the
   * real ELF note segment headers and data.
   *
   * It is assumed that program headers with PT_NOTE type pointed to by
   * @ehdr_ptr has already been updated by update_note_header_size_elf64
   * and each of PT_NOTE program headers has actual ELF note segment
   * size in its p_memsz member.
   */
  static int __init copy_notes_elf64(const Elf64_Ehdr *ehdr_ptr, char *notes_buf)
  {
  	int i, rc=0;
  	Elf64_Phdr *phdr_ptr;
  
  	phdr_ptr = (Elf64_Phdr*)(ehdr_ptr + 1);
  
  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
  		u64 offset;
  		if (phdr_ptr->p_type != PT_NOTE)
  			continue;
  		offset = phdr_ptr->p_offset;
  		rc = elfcorehdr_read_notes(notes_buf, phdr_ptr->p_memsz,
  					   &offset);
  		if (rc < 0)
  			return rc;
  		notes_buf += phdr_ptr->p_memsz;
  	}
  
  	return 0;
  }
  
  /* Merges all the PT_NOTE headers into one. */
  static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
  					   char **notes_buf, size_t *notes_sz)
  {
  	int i, nr_ptnote=0, rc=0;
  	char *tmp;
  	Elf64_Ehdr *ehdr_ptr;
  	Elf64_Phdr phdr;
  	u64 phdr_sz = 0, note_off;
  
  	ehdr_ptr = (Elf64_Ehdr *)elfptr;
  
  	rc = update_note_header_size_elf64(ehdr_ptr);
  	if (rc < 0)
  		return rc;
  
  	rc = get_note_number_and_size_elf64(ehdr_ptr, &nr_ptnote, &phdr_sz);
  	if (rc < 0)
  		return rc;
  
  	*notes_sz = roundup(phdr_sz, PAGE_SIZE);
  	*notes_buf = vmcore_alloc_buf(*notes_sz);
  	if (!*notes_buf)
  		return -ENOMEM;
  
  	rc = copy_notes_elf64(ehdr_ptr, *notes_buf);
  	if (rc < 0)
  		return rc;
  
  	/* Prepare merged PT_NOTE program header. */
  	phdr.p_type    = PT_NOTE;
  	phdr.p_flags   = 0;
  	note_off = sizeof(Elf64_Ehdr) +
  			(ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf64_Phdr);
  	phdr.p_offset  = roundup(note_off, PAGE_SIZE);
  	phdr.p_vaddr   = phdr.p_paddr = 0;
  	phdr.p_filesz  = phdr.p_memsz = phdr_sz;
  	phdr.p_align   = 0;
  
  	/* Add merged PT_NOTE program header*/
  	tmp = elfptr + sizeof(Elf64_Ehdr);
  	memcpy(tmp, &phdr, sizeof(phdr));
  	tmp += sizeof(phdr);
  
  	/* Remove unwanted PT_NOTE program headers. */
  	i = (nr_ptnote - 1) * sizeof(Elf64_Phdr);
  	*elfsz = *elfsz - i;
  	memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf64_Ehdr)-sizeof(Elf64_Phdr)));
  	memset(elfptr + *elfsz, 0, i);
  	*elfsz = roundup(*elfsz, PAGE_SIZE);
  
  	/* Modify e_phnum to reflect merged headers. */
  	ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
  
  	/* Store the size of all notes.  We need this to update the note
  	 * header when the device dumps will be added.
  	 */
  	elfnotes_orig_sz = phdr.p_memsz;
  
  	return 0;
  }
  
  /**
   * update_note_header_size_elf32 - update p_memsz member of each PT_NOTE entry
   *
   * @ehdr_ptr: ELF header
   *
   * This function updates p_memsz member of each PT_NOTE entry in the
   * program header table pointed to by @ehdr_ptr to real size of ELF
   * note segment.
   */
  static int __init update_note_header_size_elf32(const Elf32_Ehdr *ehdr_ptr)
  {
  	int i, rc=0;
  	Elf32_Phdr *phdr_ptr;
  	Elf32_Nhdr *nhdr_ptr;
  
  	phdr_ptr = (Elf32_Phdr *)(ehdr_ptr + 1);
  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
  		void *notes_section;
  		u64 offset, max_sz, sz, real_sz = 0;
  		if (phdr_ptr->p_type != PT_NOTE)
  			continue;
  		max_sz = phdr_ptr->p_memsz;
  		offset = phdr_ptr->p_offset;
  		notes_section = kmalloc(max_sz, GFP_KERNEL);
  		if (!notes_section)
  			return -ENOMEM;
  		rc = elfcorehdr_read_notes(notes_section, max_sz, &offset);
  		if (rc < 0) {
  			kfree(notes_section);
  			return rc;
  		}
  		nhdr_ptr = notes_section;
  		while (nhdr_ptr->n_namesz != 0) {
  			sz = sizeof(Elf32_Nhdr) +
  				(((u64)nhdr_ptr->n_namesz + 3) & ~3) +
  				(((u64)nhdr_ptr->n_descsz + 3) & ~3);
  			if ((real_sz + sz) > max_sz) {
  				pr_warn("Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n",
  					nhdr_ptr->n_namesz, nhdr_ptr->n_descsz);
  				break;
  			}
  			real_sz += sz;
  			nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz);
  		}
  		kfree(notes_section);
  		phdr_ptr->p_memsz = real_sz;
  		if (real_sz == 0) {
  			pr_warn("Warning: Zero PT_NOTE entries found\n");
  		}
  	}
  
  	return 0;
  }
  
  /**
   * get_note_number_and_size_elf32 - get the number of PT_NOTE program
   * headers and sum of real size of their ELF note segment headers and
   * data.
   *
   * @ehdr_ptr: ELF header
   * @nr_ptnote: buffer for the number of PT_NOTE program headers
   * @sz_ptnote: buffer for size of unique PT_NOTE program header
   *
   * This function is used to merge multiple PT_NOTE program headers
   * into a unique single one. The resulting unique entry will have
   * @sz_ptnote in its phdr->p_mem.
   *
   * It is assumed that program headers with PT_NOTE type pointed to by
   * @ehdr_ptr has already been updated by update_note_header_size_elf32
   * and each of PT_NOTE program headers has actual ELF note segment
   * size in its p_memsz member.
   */
  static int __init get_note_number_and_size_elf32(const Elf32_Ehdr *ehdr_ptr,
  						 int *nr_ptnote, u64 *sz_ptnote)
  {
  	int i;
  	Elf32_Phdr *phdr_ptr;
  
  	*nr_ptnote = *sz_ptnote = 0;
  
  	phdr_ptr = (Elf32_Phdr *)(ehdr_ptr + 1);
  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
  		if (phdr_ptr->p_type != PT_NOTE)
  			continue;
  		*nr_ptnote += 1;
  		*sz_ptnote += phdr_ptr->p_memsz;
  	}
  
  	return 0;
  }
  
  /**
   * copy_notes_elf32 - copy ELF note segments in a given buffer
   *
   * @ehdr_ptr: ELF header
   * @notes_buf: buffer into which ELF note segments are copied
   *
   * This function is used to copy ELF note segment in the 1st kernel
   * into the buffer @notes_buf in the 2nd kernel. It is assumed that
   * size of the buffer @notes_buf is equal to or larger than sum of the
   * real ELF note segment headers and data.
   *
   * It is assumed that program headers with PT_NOTE type pointed to by
   * @ehdr_ptr has already been updated by update_note_header_size_elf32
   * and each of PT_NOTE program headers has actual ELF note segment
   * size in its p_memsz member.
   */
  static int __init copy_notes_elf32(const Elf32_Ehdr *ehdr_ptr, char *notes_buf)
  {
  	int i, rc=0;
  	Elf32_Phdr *phdr_ptr;
  
  	phdr_ptr = (Elf32_Phdr*)(ehdr_ptr + 1);
  
  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
  		u64 offset;
  		if (phdr_ptr->p_type != PT_NOTE)
  			continue;
  		offset = phdr_ptr->p_offset;
  		rc = elfcorehdr_read_notes(notes_buf, phdr_ptr->p_memsz,
  					   &offset);
  		if (rc < 0)
  			return rc;
  		notes_buf += phdr_ptr->p_memsz;
  	}
  
  	return 0;
  }
  
  /* Merges all the PT_NOTE headers into one. */
  static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
  					   char **notes_buf, size_t *notes_sz)
  {
  	int i, nr_ptnote=0, rc=0;
  	char *tmp;
  	Elf32_Ehdr *ehdr_ptr;
  	Elf32_Phdr phdr;
  	u64 phdr_sz = 0, note_off;
  
  	ehdr_ptr = (Elf32_Ehdr *)elfptr;
  
  	rc = update_note_header_size_elf32(ehdr_ptr);
  	if (rc < 0)
  		return rc;
  
  	rc = get_note_number_and_size_elf32(ehdr_ptr, &nr_ptnote, &phdr_sz);
  	if (rc < 0)
  		return rc;
  
  	*notes_sz = roundup(phdr_sz, PAGE_SIZE);
  	*notes_buf = vmcore_alloc_buf(*notes_sz);
  	if (!*notes_buf)
  		return -ENOMEM;
  
  	rc = copy_notes_elf32(ehdr_ptr, *notes_buf);
  	if (rc < 0)
  		return rc;
  
  	/* Prepare merged PT_NOTE program header. */
  	phdr.p_type    = PT_NOTE;
  	phdr.p_flags   = 0;
  	note_off = sizeof(Elf32_Ehdr) +
  			(ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf32_Phdr);
  	phdr.p_offset  = roundup(note_off, PAGE_SIZE);
  	phdr.p_vaddr   = phdr.p_paddr = 0;
  	phdr.p_filesz  = phdr.p_memsz = phdr_sz;
  	phdr.p_align   = 0;
  
  	/* Add merged PT_NOTE program header*/
  	tmp = elfptr + sizeof(Elf32_Ehdr);
  	memcpy(tmp, &phdr, sizeof(phdr));
  	tmp += sizeof(phdr);
  
  	/* Remove unwanted PT_NOTE program headers. */
  	i = (nr_ptnote - 1) * sizeof(Elf32_Phdr);
  	*elfsz = *elfsz - i;
  	memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf32_Ehdr)-sizeof(Elf32_Phdr)));
  	memset(elfptr + *elfsz, 0, i);
  	*elfsz = roundup(*elfsz, PAGE_SIZE);
  
  	/* Modify e_phnum to reflect merged headers. */
  	ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
  
  	/* Store the size of all notes.  We need this to update the note
  	 * header when the device dumps will be added.
  	 */
  	elfnotes_orig_sz = phdr.p_memsz;
  
  	return 0;
  }
  
  /* Add memory chunks represented by program headers to vmcore list. Also update
   * the new offset fields of exported program headers. */
  static int __init process_ptload_program_headers_elf64(char *elfptr,
  						size_t elfsz,
  						size_t elfnotes_sz,
  						struct list_head *vc_list)
  {
  	int i;
  	Elf64_Ehdr *ehdr_ptr;
  	Elf64_Phdr *phdr_ptr;
  	loff_t vmcore_off;
  	struct vmcore *new;
  
  	ehdr_ptr = (Elf64_Ehdr *)elfptr;
  	phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); /* PT_NOTE hdr */
  
  	/* Skip Elf header, program headers and Elf note segment. */
  	vmcore_off = elfsz + elfnotes_sz;
  
  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
  		u64 paddr, start, end, size;
  
  		if (phdr_ptr->p_type != PT_LOAD)
  			continue;
  
  		paddr = phdr_ptr->p_offset;
  		start = rounddown(paddr, PAGE_SIZE);
  		end = roundup(paddr + phdr_ptr->p_memsz, PAGE_SIZE);
  		size = end - start;
  
  		/* Add this contiguous chunk of memory to vmcore list.*/
  		new = get_new_element();
  		if (!new)
  			return -ENOMEM;
  		new->paddr = start;
  		new->size = size;
  		list_add_tail(&new->list, vc_list);
  
  		/* Update the program header offset. */
  		phdr_ptr->p_offset = vmcore_off + (paddr - start);
  		vmcore_off = vmcore_off + size;
  	}
  	return 0;
  }
  
  static int __init process_ptload_program_headers_elf32(char *elfptr,
  						size_t elfsz,
  						size_t elfnotes_sz,
  						struct list_head *vc_list)
  {
  	int i;
  	Elf32_Ehdr *ehdr_ptr;
  	Elf32_Phdr *phdr_ptr;
  	loff_t vmcore_off;
  	struct vmcore *new;
  
  	ehdr_ptr = (Elf32_Ehdr *)elfptr;
  	phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); /* PT_NOTE hdr */
  
  	/* Skip Elf header, program headers and Elf note segment. */
  	vmcore_off = elfsz + elfnotes_sz;
  
  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
  		u64 paddr, start, end, size;
  
  		if (phdr_ptr->p_type != PT_LOAD)
  			continue;
  
  		paddr = phdr_ptr->p_offset;
  		start = rounddown(paddr, PAGE_SIZE);
  		end = roundup(paddr + phdr_ptr->p_memsz, PAGE_SIZE);
  		size = end - start;
  
  		/* Add this contiguous chunk of memory to vmcore list.*/
  		new = get_new_element();
  		if (!new)
  			return -ENOMEM;
  		new->paddr = start;
  		new->size = size;
  		list_add_tail(&new->list, vc_list);
  
  		/* Update the program header offset */
  		phdr_ptr->p_offset = vmcore_off + (paddr - start);
  		vmcore_off = vmcore_off + size;
  	}
  	return 0;
  }
  
  /* Sets offset fields of vmcore elements. */
  static void set_vmcore_list_offsets(size_t elfsz, size_t elfnotes_sz,
  				    struct list_head *vc_list)
  {
  	loff_t vmcore_off;
  	struct vmcore *m;
  
  	/* Skip Elf header, program headers and Elf note segment. */
  	vmcore_off = elfsz + elfnotes_sz;
  
  	list_for_each_entry(m, vc_list, list) {
  		m->offset = vmcore_off;
  		vmcore_off += m->size;
  	}
  }
  
  static void free_elfcorebuf(void)
  {
  	free_pages((unsigned long)elfcorebuf, get_order(elfcorebuf_sz_orig));
  	elfcorebuf = NULL;
  	vfree(elfnotes_buf);
  	elfnotes_buf = NULL;
  }
  
  static int __init parse_crash_elf64_headers(void)
  {
  	int rc=0;
  	Elf64_Ehdr ehdr;
  	u64 addr;
  
  	addr = elfcorehdr_addr;
  
  	/* Read Elf header */
  	rc = elfcorehdr_read((char *)&ehdr, sizeof(Elf64_Ehdr), &addr);
  	if (rc < 0)
  		return rc;
  
  	/* Do some basic Verification. */
  	if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
  		(ehdr.e_type != ET_CORE) ||
  		!vmcore_elf64_check_arch(&ehdr) ||
  		ehdr.e_ident[EI_CLASS] != ELFCLASS64 ||
  		ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
  		ehdr.e_version != EV_CURRENT ||
  		ehdr.e_ehsize != sizeof(Elf64_Ehdr) ||
  		ehdr.e_phentsize != sizeof(Elf64_Phdr) ||
  		ehdr.e_phnum == 0) {
  		pr_warn("Warning: Core image elf header is not sane\n");
  		return -EINVAL;
  	}
  
  	/* Read in all elf headers. */
  	elfcorebuf_sz_orig = sizeof(Elf64_Ehdr) +
  				ehdr.e_phnum * sizeof(Elf64_Phdr);
  	elfcorebuf_sz = elfcorebuf_sz_orig;
  	elfcorebuf = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
  					      get_order(elfcorebuf_sz_orig));
  	if (!elfcorebuf)
  		return -ENOMEM;
  	addr = elfcorehdr_addr;
  	rc = elfcorehdr_read(elfcorebuf, elfcorebuf_sz_orig, &addr);
  	if (rc < 0)
  		goto fail;
  
  	/* Merge all PT_NOTE headers into one. */
  	rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz,
  				      &elfnotes_buf, &elfnotes_sz);
  	if (rc)
  		goto fail;
  	rc = process_ptload_program_headers_elf64(elfcorebuf, elfcorebuf_sz,
  						  elfnotes_sz, &vmcore_list);
  	if (rc)
  		goto fail;
  	set_vmcore_list_offsets(elfcorebuf_sz, elfnotes_sz, &vmcore_list);
  	return 0;
  fail:
  	free_elfcorebuf();
  	return rc;
  }
  
  static int __init parse_crash_elf32_headers(void)
  {
  	int rc=0;
  	Elf32_Ehdr ehdr;
  	u64 addr;
  
  	addr = elfcorehdr_addr;
  
  	/* Read Elf header */
  	rc = elfcorehdr_read((char *)&ehdr, sizeof(Elf32_Ehdr), &addr);
  	if (rc < 0)
  		return rc;
  
  	/* Do some basic Verification. */
  	if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
  		(ehdr.e_type != ET_CORE) ||
  		!vmcore_elf32_check_arch(&ehdr) ||
  		ehdr.e_ident[EI_CLASS] != ELFCLASS32||
  		ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
  		ehdr.e_version != EV_CURRENT ||
  		ehdr.e_ehsize != sizeof(Elf32_Ehdr) ||
  		ehdr.e_phentsize != sizeof(Elf32_Phdr) ||
  		ehdr.e_phnum == 0) {
  		pr_warn("Warning: Core image elf header is not sane\n");
  		return -EINVAL;
  	}
  
  	/* Read in all elf headers. */
  	elfcorebuf_sz_orig = sizeof(Elf32_Ehdr) + ehdr.e_phnum * sizeof(Elf32_Phdr);
  	elfcorebuf_sz = elfcorebuf_sz_orig;
  	elfcorebuf = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
  					      get_order(elfcorebuf_sz_orig));
  	if (!elfcorebuf)
  		return -ENOMEM;
  	addr = elfcorehdr_addr;
  	rc = elfcorehdr_read(elfcorebuf, elfcorebuf_sz_orig, &addr);
  	if (rc < 0)
  		goto fail;
  
  	/* Merge all PT_NOTE headers into one. */
  	rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz,
  				      &elfnotes_buf, &elfnotes_sz);
  	if (rc)
  		goto fail;
  	rc = process_ptload_program_headers_elf32(elfcorebuf, elfcorebuf_sz,
  						  elfnotes_sz, &vmcore_list);
  	if (rc)
  		goto fail;
  	set_vmcore_list_offsets(elfcorebuf_sz, elfnotes_sz, &vmcore_list);
  	return 0;
  fail:
  	free_elfcorebuf();
  	return rc;
  }
  
  static int __init parse_crash_elf_headers(void)
  {
  	unsigned char e_ident[EI_NIDENT];
  	u64 addr;
  	int rc=0;
  
  	addr = elfcorehdr_addr;
  	rc = elfcorehdr_read(e_ident, EI_NIDENT, &addr);
  	if (rc < 0)
  		return rc;
  	if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
  		pr_warn("Warning: Core image elf header not found\n");
  		return -EINVAL;
  	}
  
  	if (e_ident[EI_CLASS] == ELFCLASS64) {
  		rc = parse_crash_elf64_headers();
  		if (rc)
  			return rc;
  	} else if (e_ident[EI_CLASS] == ELFCLASS32) {
  		rc = parse_crash_elf32_headers();
  		if (rc)
  			return rc;
  	} else {
  		pr_warn("Warning: Core image elf header is not sane\n");
  		return -EINVAL;
  	}
  
  	/* Determine vmcore size. */
  	vmcore_size = get_vmcore_size(elfcorebuf_sz, elfnotes_sz,
  				      &vmcore_list);
  
  	return 0;
  }
  
  #ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
  /**
   * vmcoredd_write_header - Write vmcore device dump header at the
   * beginning of the dump's buffer.
   * @buf: Output buffer where the note is written
   * @data: Dump info
   * @size: Size of the dump
   *
   * Fills beginning of the dump's buffer with vmcore device dump header.
   */
  static void vmcoredd_write_header(void *buf, struct vmcoredd_data *data,
  				  u32 size)
  {
  	struct vmcoredd_header *vdd_hdr = (struct vmcoredd_header *)buf;
  
  	vdd_hdr->n_namesz = sizeof(vdd_hdr->name);
  	vdd_hdr->n_descsz = size + sizeof(vdd_hdr->dump_name);
  	vdd_hdr->n_type = NT_VMCOREDD;
  
  	strncpy((char *)vdd_hdr->name, VMCOREDD_NOTE_NAME,
  		sizeof(vdd_hdr->name));
  	memcpy(vdd_hdr->dump_name, data->dump_name, sizeof(vdd_hdr->dump_name));
  }
  
  /**
   * vmcoredd_update_program_headers - Update all Elf program headers
   * @elfptr: Pointer to elf header
   * @elfnotesz: Size of elf notes aligned to page size
   * @vmcoreddsz: Size of device dumps to be added to elf note header
   *
   * Determine type of Elf header (Elf64 or Elf32) and update the elf note size.
   * Also update the offsets of all the program headers after the elf note header.
   */
  static void vmcoredd_update_program_headers(char *elfptr, size_t elfnotesz,
  					    size_t vmcoreddsz)
  {
  	unsigned char *e_ident = (unsigned char *)elfptr;
  	u64 start, end, size;
  	loff_t vmcore_off;
  	u32 i;
  
  	vmcore_off = elfcorebuf_sz + elfnotesz;
  
  	if (e_ident[EI_CLASS] == ELFCLASS64) {
  		Elf64_Ehdr *ehdr = (Elf64_Ehdr *)elfptr;
  		Elf64_Phdr *phdr = (Elf64_Phdr *)(elfptr + sizeof(Elf64_Ehdr));
  
  		/* Update all program headers */
  		for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
  			if (phdr->p_type == PT_NOTE) {
  				/* Update note size */
  				phdr->p_memsz = elfnotes_orig_sz + vmcoreddsz;
  				phdr->p_filesz = phdr->p_memsz;
  				continue;
  			}
  
  			start = rounddown(phdr->p_offset, PAGE_SIZE);
  			end = roundup(phdr->p_offset + phdr->p_memsz,
  				      PAGE_SIZE);
  			size = end - start;
  			phdr->p_offset = vmcore_off + (phdr->p_offset - start);
  			vmcore_off += size;
  		}
  	} else {
  		Elf32_Ehdr *ehdr = (Elf32_Ehdr *)elfptr;
  		Elf32_Phdr *phdr = (Elf32_Phdr *)(elfptr + sizeof(Elf32_Ehdr));
  
  		/* Update all program headers */
  		for (i = 0; i < ehdr->e_phnum; i++, phdr++) {
  			if (phdr->p_type == PT_NOTE) {
  				/* Update note size */
  				phdr->p_memsz = elfnotes_orig_sz + vmcoreddsz;
  				phdr->p_filesz = phdr->p_memsz;
  				continue;
  			}
  
  			start = rounddown(phdr->p_offset, PAGE_SIZE);
  			end = roundup(phdr->p_offset + phdr->p_memsz,
  				      PAGE_SIZE);
  			size = end - start;
  			phdr->p_offset = vmcore_off + (phdr->p_offset - start);
  			vmcore_off += size;
  		}
  	}
  }
  
  /**
   * vmcoredd_update_size - Update the total size of the device dumps and update
   * Elf header
   * @dump_size: Size of the current device dump to be added to total size
   *
   * Update the total size of all the device dumps and update the Elf program
   * headers. Calculate the new offsets for the vmcore list and update the
   * total vmcore size.
   */
  static void vmcoredd_update_size(size_t dump_size)
  {
  	vmcoredd_orig_sz += dump_size;
  	elfnotes_sz = roundup(elfnotes_orig_sz, PAGE_SIZE) + vmcoredd_orig_sz;
  	vmcoredd_update_program_headers(elfcorebuf, elfnotes_sz,
  					vmcoredd_orig_sz);
  
  	/* Update vmcore list offsets */
  	set_vmcore_list_offsets(elfcorebuf_sz, elfnotes_sz, &vmcore_list);
  
  	vmcore_size = get_vmcore_size(elfcorebuf_sz, elfnotes_sz,
  				      &vmcore_list);
  	proc_vmcore->size = vmcore_size;
  }
  
  /**
   * vmcore_add_device_dump - Add a buffer containing device dump to vmcore
   * @data: dump info.
   *
   * Allocate a buffer and invoke the calling driver's dump collect routine.
   * Write Elf note at the beginning of the buffer to indicate vmcore device
   * dump and add the dump to global list.
   */
  int vmcore_add_device_dump(struct vmcoredd_data *data)
  {
  	struct vmcoredd_node *dump;
  	void *buf = NULL;
  	size_t data_size;
  	int ret;
  
  	if (vmcoredd_disabled) {
  		pr_err_once("Device dump is disabled\n");
  		return -EINVAL;
  	}
  
  	if (!data || !strlen(data->dump_name) ||
  	    !data->vmcoredd_callback || !data->size)
  		return -EINVAL;
  
  	dump = vzalloc(sizeof(*dump));
  	if (!dump) {
  		ret = -ENOMEM;
  		goto out_err;
  	}
  
  	/* Keep size of the buffer page aligned so that it can be mmaped */
  	data_size = roundup(sizeof(struct vmcoredd_header) + data->size,
  			    PAGE_SIZE);
  
  	/* Allocate buffer for driver's to write their dumps */
  	buf = vmcore_alloc_buf(data_size);
  	if (!buf) {
  		ret = -ENOMEM;
  		goto out_err;
  	}
  
  	vmcoredd_write_header(buf, data, data_size -
  			      sizeof(struct vmcoredd_header));
  
  	/* Invoke the driver's dump collection routing */
  	ret = data->vmcoredd_callback(data, buf +
  				      sizeof(struct vmcoredd_header));
  	if (ret)
  		goto out_err;
  
  	dump->buf = buf;
  	dump->size = data_size;
  
  	/* Add the dump to driver sysfs list */
  	mutex_lock(&vmcoredd_mutex);
  	list_add_tail(&dump->list, &vmcoredd_list);
  	mutex_unlock(&vmcoredd_mutex);
  
  	vmcoredd_update_size(data_size);
  	return 0;
  
  out_err:
  	vfree(buf);
  	vfree(dump);
  
  	return ret;
  }
  EXPORT_SYMBOL(vmcore_add_device_dump);
  #endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */
  
  /* Free all dumps in vmcore device dump list */
  static void vmcore_free_device_dumps(void)
  {
  #ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
  	mutex_lock(&vmcoredd_mutex);
  	while (!list_empty(&vmcoredd_list)) {
  		struct vmcoredd_node *dump;
  
  		dump = list_first_entry(&vmcoredd_list, struct vmcoredd_node,
  					list);
  		list_del(&dump->list);
  		vfree(dump->buf);
  		vfree(dump);
  	}
  	mutex_unlock(&vmcoredd_mutex);
  #endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */
  }
  
  /* Init function for vmcore module. */
  static int __init vmcore_init(void)
  {
  	int rc = 0;
  
  	/* Allow architectures to allocate ELF header in 2nd kernel */
  	rc = elfcorehdr_alloc(&elfcorehdr_addr, &elfcorehdr_size);
  	if (rc)
  		return rc;
  	/*
  	 * If elfcorehdr= has been passed in cmdline or created in 2nd kernel,
  	 * then capture the dump.
  	 */
  	if (!(is_vmcore_usable()))
  		return rc;
  	rc = parse_crash_elf_headers();
  	if (rc) {
  		pr_warn("Kdump: vmcore not initialized\n");
  		return rc;
  	}
  	elfcorehdr_free(elfcorehdr_addr);
  	elfcorehdr_addr = ELFCORE_ADDR_ERR;
  
  	proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &vmcore_proc_ops);
  	if (proc_vmcore)
  		proc_vmcore->size = vmcore_size;
  	return 0;
  }
  fs_initcall(vmcore_init);
  
  /* Cleanup function for vmcore module. */
  void vmcore_cleanup(void)
  {
  	if (proc_vmcore) {
  		proc_remove(proc_vmcore);
  		proc_vmcore = NULL;
  	}
  
  	/* clear the vmcore list. */
  	while (!list_empty(&vmcore_list)) {
  		struct vmcore *m;
  
  		m = list_first_entry(&vmcore_list, struct vmcore, list);
  		list_del(&m->list);
  		kfree(m);
  	}
  	free_elfcorebuf();
  
  	/* clear vmcore device dump list */
  	vmcore_free_device_dumps();
  }
  