1/*
2 *	kernel/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
8#include <linux/errno.h>
9#include <linux/crash_dump.h>
10
11#include <asm/uaccess.h>
12#include <asm/io.h>
13
14/**
15 * copy_oldmem_page - copy one page from "oldmem"
16 * @pfn: page frame number to be copied
17 * @buf: target memory address for the copy; this can be in kernel address
18 *	space or user address space (see @userbuf)
19 * @csize: number of bytes to copy
20 * @offset: offset in bytes into the page (based on pfn) to begin the copy
21 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
22 *	otherwise @buf is in kernel address space, use memcpy().
23 *
24 * Copy a page from "oldmem". For this page, there is no pte mapped
25 * in the current kernel. We stitch up a pte, similar to kmap_atomic.
26 */
27ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
28                               size_t csize, unsigned long offset, int userbuf)
29{
30	void  *vaddr;
31
32	if (!csize)
33		return 0;
34
35	vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
36
37	if (userbuf) {
38		if (copy_to_user(buf, (vaddr + offset), csize)) {
39			iounmap(vaddr);
40			return -EFAULT;
41		}
42	} else
43	memcpy(buf, (vaddr + offset), csize);
44
45	iounmap(vaddr);
46	return csize;
47}
48