1// SPDX-License-Identifier: GPL-2.0
2/*
3 *	crash_dump.c - Memory preserving reboot related code.
4 *
5 *	Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
6 *	Copyright (C) IBM Corporation, 2004. All rights reserved
7 */
8#include <linux/errno.h>
9#include <linux/crash_dump.h>
10#include <linux/io.h>
11#include <linux/uio.h>
12#include <linux/uaccess.h>
13
14ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
15			 size_t csize, unsigned long offset)
16{
17	void  __iomem *vaddr;
18
19	if (!csize)
20		return 0;
21
22	vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
23	csize = copy_to_iter(vaddr + offset, csize, iter);
24	iounmap(vaddr);
25
26	return csize;
27}
28