// SPDX-License-Identifier: GPL-2.0
/*
 *      crash_dump.c - Memory preserving reboot related code.
 *
 *      Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
 *      Copyright (C) IBM Corporation, 2004. All rights reserved
 */
#include <linux/errno.h>
#include <linux/crash_dump.h>
#include <linux/io.h>
#include <linux/uio.h>
#include <linux/uaccess.h>

ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
                         size_t csize, unsigned long offset)
{
        void  __iomem *vaddr;

        if (!csize)
                return 0;

        vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
        csize = copy_to_iter(vaddr + offset, csize, iter);
        iounmap(vaddr);

        return csize;
}