1/*
2 *	crash_dump.c - Memory preserving reboot related code.
3 *
4 *	Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
5 *	Copyright (C) IBM Corporation, 2004. All rights reserved
6 */
7#include <linux/errno.h>
8#include <linux/crash_dump.h>
9#include <linux/io.h>
10#include <asm/uaccess.h>
11
12/**
13 * copy_oldmem_page - copy one page from "oldmem"
14 * @pfn: page frame number to be copied
15 * @buf: target memory address for the copy; this can be in kernel address
16 *	space or user address space (see @userbuf)
17 * @csize: number of bytes to copy
18 * @offset: offset in bytes into the page (based on pfn) to begin the copy
19 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
20 *	otherwise @buf is in kernel address space, use memcpy().
21 *
22 * Copy a page from "oldmem". For this page, there is no pte mapped
23 * in the current kernel. We stitch up a pte, similar to kmap_atomic.
24 */
25ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
26                               size_t csize, unsigned long offset, int userbuf)
27{
28	void  *vaddr;
29
30	if (!csize)
31		return 0;
32
33	vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
34
35	if (userbuf) {
36		if (copy_to_user(buf, (vaddr + offset), csize)) {
37			iounmap(vaddr);
38			return -EFAULT;
39		}
40	} else
41	memcpy(buf, (vaddr + offset), csize);
42
43	iounmap(vaddr);
44	return csize;
45}
46