vmcore.c

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/*
 *  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 ([email protected])
 *  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/export.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)

/* Cleanup function for vmcore module. */
void vmcore_cleanup(void)
{
    struct list_head *pos, *next;

    if (proc_vmcore) {
        remove_proc_entry(proc_vmcore->name, proc_vmcore->parent);
        proc_vmcore = NULL;
    }

    /* clear the vmcore list. */
    list_for_each_safe(pos, next, &vmcore_list) {
        struct vmcore *m;

        m = list_entry(pos, struct vmcore, list);
        list_del(&m->list);
        kfree(m);
    }
    kfree(elfcorebuf);
    elfcorebuf = NULL;
}
EXPORT_SYMBOL_GPL(vmcore_cleanup);