crash_dump.c

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/*
 *  crash_dump.c - Memory preserving reboot related code.
 *
 *  Created by: Hariprasad Nellitheertha ([email protected])
 *  Copyright (C) IBM Corporation, 2004. All rights reserved
 */
#include <linux/errno.h>
#include <linux/crash_dump.h>
#include <linux/io.h>
#include <asm/uaccess.h>

ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
                               size_t csize, unsigned long offset, int userbuf)
{
    void  *vaddr;

    if (!csize)
        return 0;

    vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);

    if (userbuf) {
        if (copy_to_user(buf, (vaddr + offset), csize)) {
            iounmap(vaddr);
            return -EFAULT;
        }
    } else
    memcpy(buf, (vaddr + offset), csize);

    iounmap(vaddr);
    return csize;
}