1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * This code comes from arch/arm64/kernel/crash_dump.c
 4 * Created by: AKASHI Takahiro <takahiro.akashi@linaro.org>
 5 * Copyright (C) 2017 Linaro Limited
 6 */
 7
 8#include <linux/crash_dump.h>
 9#include <linux/io.h>
10#include <linux/uio.h>
11
12ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn,
13			 size_t csize, unsigned long offset)
14{
15	void *vaddr;
16
17	if (!csize)
18		return 0;
19
20	vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB);
21	if (!vaddr)
22		return -ENOMEM;
23
24	csize = copy_to_iter(vaddr + offset, csize, iter);
25
26	memunmap(vaddr);
27	return csize;
28}