text: /*
   *	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/proc_fs.h>
  #include <linux/user.h>
  #include <linux/elf.h>
  #include <linux/elfcore.h>
  #include <linux/slab.h>
  #include <linux/highmem.h>
  #include <linux/bootmem.h>
  #include <linux/init.h>
  #include <linux/crash_dump.h>
  #include <linux/list.h>
  #include <asm/uaccess.h>
  #include <asm/io.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;
  
  /* Total size of vmcore file. */
  static u64 vmcore_size;
  
  static struct proc_dir_entry *proc_vmcore = NULL;
  
  /*
   * 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. */
  static ssize_t read_from_oldmem(char *buf, size_t count,
  				u64 *ppos, int userbuf)
  {
  	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 {
  			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;
  }
  
  /* Maps vmcore file offset to respective physical address in memroy. */
  static u64 map_offset_to_paddr(loff_t offset, struct list_head *vc_list,
  					struct vmcore **m_ptr)
  {
  	struct vmcore *m;
  	u64 paddr;
  
  	list_for_each_entry(m, vc_list, list) {
  		u64 start, end;
  		start = m->offset;
  		end = m->offset + m->size - 1;
  		if (offset >= start && offset <= end) {
  			paddr = m->paddr + offset - start;
  			*m_ptr = m;
  			return paddr;
  		}
  	}
  	*m_ptr = NULL;
  	return 0;
  }
  
  /* 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(struct file *file, char __user *buffer,
  				size_t buflen, loff_t *fpos)
  {
  	ssize_t acc = 0, tmp;
  	size_t tsz;
  	u64 start, nr_bytes;
  	struct vmcore *curr_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 = elfcorebuf_sz - *fpos;
  		if (buflen < tsz)
  			tsz = buflen;
  		if (copy_to_user(buffer, elfcorebuf + *fpos, tsz))
  			return -EFAULT;
  		buflen -= tsz;
  		*fpos += tsz;
  		buffer += tsz;
  		acc += tsz;
  
  		/* leave now if filled buffer already */
  		if (buflen == 0)
  			return acc;
  	}
  
  	start = map_offset_to_paddr(*fpos, &vmcore_list, &curr_m);
  	if (!curr_m)
          	return -EINVAL;
  	if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
  		tsz = buflen;
  
  	/* Calculate left bytes in current memory segment. */
  	nr_bytes = (curr_m->size - (start - curr_m->paddr));
  	if (tsz > nr_bytes)
  		tsz = nr_bytes;
  
  	while (buflen) {
  		tmp = read_from_oldmem(buffer, tsz, &start, 1);
  		if (tmp < 0)
  			return tmp;
  		buflen -= tsz;
  		*fpos += tsz;
  		buffer += tsz;
  		acc += tsz;
  		if (start >= (curr_m->paddr + curr_m->size)) {
  			if (curr_m->list.next == &vmcore_list)
  				return acc;	/*EOF*/
  			curr_m = list_entry(curr_m->list.next,
  						struct vmcore, list);
  			start = curr_m->paddr;
  		}
  		if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
  			tsz = buflen;
  		/* Calculate left bytes in current memory segment. */
  		nr_bytes = (curr_m->size - (start - curr_m->paddr));
  		if (tsz > nr_bytes)
  			tsz = nr_bytes;
  	}
  	return acc;
  }
  
  static const struct file_operations proc_vmcore_operations = {
  	.read		= read_vmcore,
  	.llseek		= default_llseek,
  };
  
  static struct vmcore* __init get_new_element(void)
  {
  	return kzalloc(sizeof(struct vmcore), GFP_KERNEL);
  }
  
  static u64 __init get_vmcore_size_elf64(char *elfptr)
  {
  	int i;
  	u64 size;
  	Elf64_Ehdr *ehdr_ptr;
  	Elf64_Phdr *phdr_ptr;
  
  	ehdr_ptr = (Elf64_Ehdr *)elfptr;
  	phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
  	size = sizeof(Elf64_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr));
  	for (i = 0; i < ehdr_ptr->e_phnum; i++) {
  		size += phdr_ptr->p_memsz;
  		phdr_ptr++;
  	}
  	return size;
  }
  
  static u64 __init get_vmcore_size_elf32(char *elfptr)
  {
  	int i;
  	u64 size;
  	Elf32_Ehdr *ehdr_ptr;
  	Elf32_Phdr *phdr_ptr;
  
  	ehdr_ptr = (Elf32_Ehdr *)elfptr;
  	phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
  	size = sizeof(Elf32_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr));
  	for (i = 0; i < ehdr_ptr->e_phnum; i++) {
  		size += phdr_ptr->p_memsz;
  		phdr_ptr++;
  	}
  	return size;
  }
  
  /* Merges all the PT_NOTE headers into one. */
  static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
  						struct list_head *vc_list)
  {
  	int i, nr_ptnote=0, rc=0;
  	char *tmp;
  	Elf64_Ehdr *ehdr_ptr;
  	Elf64_Phdr phdr, *phdr_ptr;
  	Elf64_Nhdr *nhdr_ptr;
  	u64 phdr_sz = 0, note_off;
  
  	ehdr_ptr = (Elf64_Ehdr *)elfptr;
  	phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
  		int j;
  		void *notes_section;
  		struct vmcore *new;
  		u64 offset, max_sz, sz, real_sz = 0;
  		if (phdr_ptr->p_type != PT_NOTE)
  			continue;
  		nr_ptnote++;
  		max_sz = phdr_ptr->p_memsz;
  		offset = phdr_ptr->p_offset;
  		notes_section = kmalloc(max_sz, GFP_KERNEL);
  		if (!notes_section)
  			return -ENOMEM;
  		rc = read_from_oldmem(notes_section, max_sz, &offset, 0);
  		if (rc < 0) {
  			kfree(notes_section);
  			return rc;
  		}
  		nhdr_ptr = notes_section;
  		for (j = 0; j < max_sz; j += sz) {
  			if (nhdr_ptr->n_namesz == 0)
  				break;
  			sz = sizeof(Elf64_Nhdr) +
  				((nhdr_ptr->n_namesz + 3) & ~3) +
  				((nhdr_ptr->n_descsz + 3) & ~3);
  			real_sz += sz;
  			nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz);
  		}
  
  		/* Add this contiguous chunk of notes section to vmcore list.*/
  		new = get_new_element();
  		if (!new) {
  			kfree(notes_section);
  			return -ENOMEM;
  		}
  		new->paddr = phdr_ptr->p_offset;
  		new->size = real_sz;
  		list_add_tail(&new->list, vc_list);
  		phdr_sz += real_sz;
  		kfree(notes_section);
  	}
  
  	/* 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  = note_off;
  	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)));
  
  	/* Modify e_phnum to reflect merged headers. */
  	ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
  
  	return 0;
  }
  
  /* Merges all the PT_NOTE headers into one. */
  static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
  						struct list_head *vc_list)
  {
  	int i, nr_ptnote=0, rc=0;
  	char *tmp;
  	Elf32_Ehdr *ehdr_ptr;
  	Elf32_Phdr phdr, *phdr_ptr;
  	Elf32_Nhdr *nhdr_ptr;
  	u64 phdr_sz = 0, note_off;
  
  	ehdr_ptr = (Elf32_Ehdr *)elfptr;
  	phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
  		int j;
  		void *notes_section;
  		struct vmcore *new;
  		u64 offset, max_sz, sz, real_sz = 0;
  		if (phdr_ptr->p_type != PT_NOTE)
  			continue;
  		nr_ptnote++;
  		max_sz = phdr_ptr->p_memsz;
  		offset = phdr_ptr->p_offset;
  		notes_section = kmalloc(max_sz, GFP_KERNEL);
  		if (!notes_section)
  			return -ENOMEM;
  		rc = read_from_oldmem(notes_section, max_sz, &offset, 0);
  		if (rc < 0) {
  			kfree(notes_section);
  			return rc;
  		}
  		nhdr_ptr = notes_section;
  		for (j = 0; j < max_sz; j += sz) {
  			if (nhdr_ptr->n_namesz == 0)
  				break;
  			sz = sizeof(Elf32_Nhdr) +
  				((nhdr_ptr->n_namesz + 3) & ~3) +
  				((nhdr_ptr->n_descsz + 3) & ~3);
  			real_sz += sz;
  			nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz);
  		}
  
  		/* Add this contiguous chunk of notes section to vmcore list.*/
  		new = get_new_element();
  		if (!new) {
  			kfree(notes_section);
  			return -ENOMEM;
  		}
  		new->paddr = phdr_ptr->p_offset;
  		new->size = real_sz;
  		list_add_tail(&new->list, vc_list);
  		phdr_sz += real_sz;
  		kfree(notes_section);
  	}
  
  	/* 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  = note_off;
  	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)));
  
  	/* Modify e_phnum to reflect merged headers. */
  	ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
  
  	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,
  						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 */
  
  	/* First program header is PT_NOTE header. */
  	vmcore_off = sizeof(Elf64_Ehdr) +
  			(ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr) +
  			phdr_ptr->p_memsz; /* Note sections */
  
  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
  		if (phdr_ptr->p_type != PT_LOAD)
  			continue;
  
  		/* Add this contiguous chunk of memory to vmcore list.*/
  		new = get_new_element();
  		if (!new)
  			return -ENOMEM;
  		new->paddr = phdr_ptr->p_offset;
  		new->size = phdr_ptr->p_memsz;
  		list_add_tail(&new->list, vc_list);
  
  		/* Update the program header offset. */
  		phdr_ptr->p_offset = vmcore_off;
  		vmcore_off = vmcore_off + phdr_ptr->p_memsz;
  	}
  	return 0;
  }
  
  static int __init process_ptload_program_headers_elf32(char *elfptr,
  						size_t elfsz,
  						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 */
  
  	/* First program header is PT_NOTE header. */
  	vmcore_off = sizeof(Elf32_Ehdr) +
  			(ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr) +
  			phdr_ptr->p_memsz; /* Note sections */
  
  	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
  		if (phdr_ptr->p_type != PT_LOAD)
  			continue;
  
  		/* Add this contiguous chunk of memory to vmcore list.*/
  		new = get_new_element();
  		if (!new)
  			return -ENOMEM;
  		new->paddr = phdr_ptr->p_offset;
  		new->size = phdr_ptr->p_memsz;
  		list_add_tail(&new->list, vc_list);
  
  		/* Update the program header offset */
  		phdr_ptr->p_offset = vmcore_off;
  		vmcore_off = vmcore_off + phdr_ptr->p_memsz;
  	}
  	return 0;
  }
  
  /* Sets offset fields of vmcore elements. */
  static void __init set_vmcore_list_offsets_elf64(char *elfptr,
  						struct list_head *vc_list)
  {
  	loff_t vmcore_off;
  	Elf64_Ehdr *ehdr_ptr;
  	struct vmcore *m;
  
  	ehdr_ptr = (Elf64_Ehdr *)elfptr;
  
  	/* Skip Elf header and program headers. */
  	vmcore_off = sizeof(Elf64_Ehdr) +
  			(ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr);
  
  	list_for_each_entry(m, vc_list, list) {
  		m->offset = vmcore_off;
  		vmcore_off += m->size;
  	}
  }
  
  /* Sets offset fields of vmcore elements. */
  static void __init set_vmcore_list_offsets_elf32(char *elfptr,
  						struct list_head *vc_list)
  {
  	loff_t vmcore_off;
  	Elf32_Ehdr *ehdr_ptr;
  	struct vmcore *m;
  
  	ehdr_ptr = (Elf32_Ehdr *)elfptr;
  
  	/* Skip Elf header and program headers. */
  	vmcore_off = sizeof(Elf32_Ehdr) +
  			(ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr);
  
  	list_for_each_entry(m, vc_list, list) {
  		m->offset = vmcore_off;
  		vmcore_off += m->size;
  	}
  }
  
  static int __init parse_crash_elf64_headers(void)
  {
  	int rc=0;
  	Elf64_Ehdr ehdr;
  	u64 addr;
  
  	addr = elfcorehdr_addr;
  
  	/* Read Elf header */
  	rc = read_from_oldmem((char*)&ehdr, sizeof(Elf64_Ehdr), &addr, 0);
  	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) {
  		printk(KERN_WARNING "Warning: Core image elf header is not"
  					"sane\n");
  		return -EINVAL;
  	}
  
  	/* Read in all elf headers. */
  	elfcorebuf_sz = sizeof(Elf64_Ehdr) + ehdr.e_phnum * sizeof(Elf64_Phdr);
  	elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL);
  	if (!elfcorebuf)
  		return -ENOMEM;
  	addr = elfcorehdr_addr;
  	rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0);
  	if (rc < 0) {
  		kfree(elfcorebuf);
  		return rc;
  	}
  
  	/* Merge all PT_NOTE headers into one. */
  	rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
  	if (rc) {
  		kfree(elfcorebuf);
  		return rc;
  	}
  	rc = process_ptload_program_headers_elf64(elfcorebuf, elfcorebuf_sz,
  							&vmcore_list);
  	if (rc) {
  		kfree(elfcorebuf);
  		return rc;
  	}
  	set_vmcore_list_offsets_elf64(elfcorebuf, &vmcore_list);
  	return 0;
  }
  
  static int __init parse_crash_elf32_headers(void)
  {
  	int rc=0;
  	Elf32_Ehdr ehdr;
  	u64 addr;
  
  	addr = elfcorehdr_addr;
  
  	/* Read Elf header */
  	rc = read_from_oldmem((char*)&ehdr, sizeof(Elf32_Ehdr), &addr, 0);
  	if (rc < 0)
  		return rc;
  
  	/* Do some basic Verification. */
  	if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
  		(ehdr.e_type != ET_CORE) ||
  		!elf_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) {
  		printk(KERN_WARNING "Warning: Core image elf header is not"
  					"sane\n");
  		return -EINVAL;
  	}
  
  	/* Read in all elf headers. */
  	elfcorebuf_sz = sizeof(Elf32_Ehdr) + ehdr.e_phnum * sizeof(Elf32_Phdr);
  	elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL);
  	if (!elfcorebuf)
  		return -ENOMEM;
  	addr = elfcorehdr_addr;
  	rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0);
  	if (rc < 0) {
  		kfree(elfcorebuf);
  		return rc;
  	}
  
  	/* Merge all PT_NOTE headers into one. */
  	rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
  	if (rc) {
  		kfree(elfcorebuf);
  		return rc;
  	}
  	rc = process_ptload_program_headers_elf32(elfcorebuf, elfcorebuf_sz,
  								&vmcore_list);
  	if (rc) {
  		kfree(elfcorebuf);
  		return rc;
  	}
  	set_vmcore_list_offsets_elf32(elfcorebuf, &vmcore_list);
  	return 0;
  }
  
  static int __init parse_crash_elf_headers(void)
  {
  	unsigned char e_ident[EI_NIDENT];
  	u64 addr;
  	int rc=0;
  
  	addr = elfcorehdr_addr;
  	rc = read_from_oldmem(e_ident, EI_NIDENT, &addr, 0);
  	if (rc < 0)
  		return rc;
  	if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
  		printk(KERN_WARNING "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;
  
  		/* Determine vmcore size. */
  		vmcore_size = get_vmcore_size_elf64(elfcorebuf);
  	} else if (e_ident[EI_CLASS] == ELFCLASS32) {
  		rc = parse_crash_elf32_headers();
  		if (rc)
  			return rc;
  
  		/* Determine vmcore size. */
  		vmcore_size = get_vmcore_size_elf32(elfcorebuf);
  	} else {
  		printk(KERN_WARNING "Warning: Core image elf header is not"
  					" sane\n");
  		return -EINVAL;
  	}
  	return 0;
  }
  
  /* Init function for vmcore module. */
  static int __init vmcore_init(void)
  {
  	int rc = 0;
  
  	/* If elfcorehdr= has been passed in cmdline, then capture the dump.*/
  	if (!(is_vmcore_usable()))
  		return rc;
  	rc = parse_crash_elf_headers();
  	if (rc) {
  		printk(KERN_WARNING "Kdump: vmcore not initialized\n");
  		return rc;
  	}
  
  	proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &proc_vmcore_operations);
  	if (proc_vmcore)
  		proc_vmcore->size = vmcore_size;
  	return 0;
  }
  module_init(vmcore_init)
  