xref: /linux/arch/x86/kernel/crash_dump_64.c (revision d39d0ed196aa1685bb24771e92f78633c66ac9cb)
1 /*
2  *	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 #include <linux/uaccess.h>
11 #include <linux/io.h>
12 
13 /* Stores the physical address of elf header of crash image. */
14 unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
15 
16 /**
17  * copy_oldmem_page - copy one page from "oldmem"
18  * @pfn: page frame number to be copied
19  * @buf: target memory address for the copy; this can be in kernel address
20  *	space or user address space (see @userbuf)
21  * @csize: number of bytes to copy
22  * @offset: offset in bytes into the page (based on pfn) to begin the copy
23  * @userbuf: if set, @buf is in user address space, use copy_to_user(),
24  *	otherwise @buf is in kernel address space, use memcpy().
25  *
26  * Copy a page from "oldmem". For this page, there is no pte mapped
27  * in the current kernel. We stitch up a pte, similar to kmap_atomic.
28  */
29 ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
30 		size_t csize, unsigned long offset, int userbuf)
31 {
32 	void  *vaddr;
33 
34 	if (!csize)
35 		return 0;
36 
37 	vaddr = ioremap(pfn << PAGE_SHIFT, PAGE_SIZE);
38 	if (!vaddr)
39 		return -ENOMEM;
40 
41 	if (userbuf) {
42 		if (copy_to_user(buf, vaddr + offset, csize)) {
43 			iounmap(vaddr);
44 			return -EFAULT;
45 		}
46 	} else
47 		memcpy(buf, vaddr + offset, csize);
48 
49 	iounmap(vaddr);
50 	return csize;
51 }
52