summaryrefslogtreecommitdiff
path: root/arch/x86/kernel/crash_dump_64.c
blob: 97529552dd2496421cd7f684c38e7a3629ad40c5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
// SPDX-License-Identifier: GPL-2.0
/*
 *	Memory preserving reboot related code.
 *
 *	Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
 *	Copyright (C) IBM Corporation, 2004. All rights reserved
 */

#include <linux/errno.h>
#include <linux/crash_dump.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/cc_platform.h>

static ssize_t __copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
				  unsigned long offset, int userbuf,
				  bool encrypted)
{
	void  *vaddr;

	if (!csize)
		return 0;

	if (encrypted)
		vaddr = (__force void *)ioremap_encrypted(pfn << PAGE_SHIFT, PAGE_SIZE);
	else
		vaddr = (__force void *)ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE);

	if (!vaddr)
		return -ENOMEM;

	if (userbuf) {
		if (copy_to_user((void __user *)buf, vaddr + offset, csize)) {
			iounmap((void __iomem *)vaddr);
			return -EFAULT;
		}
	} else
		memcpy(buf, vaddr + offset, csize);

	iounmap((void __iomem *)vaddr);
	return csize;
}

/**
 * copy_oldmem_page - copy one page of memory
 * @pfn: page frame number to be copied
 * @buf: target memory address for the copy; this can be in kernel address
 *	space or user address space (see @userbuf)
 * @csize: number of bytes to copy
 * @offset: offset in bytes into the page (based on pfn) to begin the copy
 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
 *	otherwise @buf is in kernel address space, use memcpy().
 *
 * Copy a page from the old kernel's memory. For this page, there is no pte
 * mapped in the current kernel. We stitch up a pte, similar to kmap_atomic.
 */
ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
			 unsigned long offset, int userbuf)
{
	return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, false);
}

/**
 * copy_oldmem_page_encrypted - same as copy_oldmem_page() above but ioremap the
 * memory with the encryption mask set to accommodate kdump on SME-enabled
 * machines.
 */
ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
				   unsigned long offset, int userbuf)
{
	return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, true);
}

ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
{
	return read_from_oldmem(buf, count, ppos, 0,
				cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT));
}