fs/proc/vmcore.c - kernel/msm-4.9 - Gitiles

 /*
  *	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/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;

 /* Stores the physical address of elf header of crash image. */
 unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;

 struct proc_dir_entry *proc_vmcore = NULL;

 /* 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);
 	if (pfn > saved_max_pfn)
 		return -EINVAL;

 	do {
 		if (count > (PAGE_SIZE - offset))
 			nr_bytes = PAGE_SIZE - offset;
 		else
 			nr_bytes = count;

 		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 int open_vmcore(struct inode *inode, struct file *filp)
 {
 	return 0;
 }

 const struct file_operations proc_vmcore_operations = {
 	.read		= read_vmcore,
 	.open		= open_vmcore,
 };

 static struct vmcore* __init get_new_element(void)
 {
 	struct vmcore *p;

 	p = kmalloc(sizeof(*p), GFP_KERNEL);
 	if (p)
 		memset(p, 0, sizeof(*p));
 	return p;
 }

 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_elf_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 (!(elfcorehdr_addr < ELFCORE_ADDR_MAX))
 		return rc;
 	rc = parse_crash_elf_headers();
 	if (rc) {
 		printk(KERN_WARNING "Kdump: vmcore not initialized\n");
 		return rc;
 	}

 	/* Initialize /proc/vmcore size if proc is already up. */
 	if (proc_vmcore)
 		proc_vmcore->size = vmcore_size;
 	return 0;
 }
 module_init(vmcore_init)
	/*
	* 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/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;

	/* Stores the physical address of elf header of crash image. */
	unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;

	struct proc_dir_entry *proc_vmcore = NULL;

	/* 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);
	if (pfn > saved_max_pfn)
	return -EINVAL;

	do {
	if (count > (PAGE_SIZE - offset))
	nr_bytes = PAGE_SIZE - offset;
	else
	nr_bytes = count;

	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 int open_vmcore(struct inode inode, struct file filp)
	{
	return 0;
	}

	const struct file_operations proc_vmcore_operations = {
	.read = read_vmcore,
	.open = open_vmcore,
	};

	static struct vmcore* __init get_new_element(void)
	{
	struct vmcore *p;

	p = kmalloc(sizeof(*p), GFP_KERNEL);
	if (p)
	memset(p, 0, sizeof(*p));
	return p;
	}

	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_elf_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 (!(elfcorehdr_addr < ELFCORE_ADDR_MAX))
	return rc;
	rc = parse_crash_elf_headers();
	if (rc) {
	printk(KERN_WARNING "Kdump: vmcore not initialized\n");
	return rc;
	}

	/* Initialize /proc/vmcore size if proc is already up. */
	if (proc_vmcore)
	proc_vmcore->size = vmcore_size;
	return 0;
	}
	module_init(vmcore_init)