1/*
2 * purgatory: Runs between two kernels
3 *
4 * Copyright (C) 2014 Red Hat Inc.
5 *
6 * Author:
7 *       Vivek Goyal <vgoyal@redhat.com>
8 *
9 * This source code is licensed under the GNU General Public License,
10 * Version 2.  See the file COPYING for more details.
11 */
12
13#include "sha256.h"
14#include "../boot/string.h"
15
16struct sha_region {
17	unsigned long start;
18	unsigned long len;
19};
20
21unsigned long backup_dest = 0;
22unsigned long backup_src = 0;
23unsigned long backup_sz = 0;
24
25u8 sha256_digest[SHA256_DIGEST_SIZE] = { 0 };
26
27struct sha_region sha_regions[16] = {};
28
29/*
30 * On x86, second kernel requries first 640K of memory to boot. Copy
31 * first 640K to a backup region in reserved memory range so that second
32 * kernel can use first 640K.
33 */
34static int copy_backup_region(void)
35{
36	if (backup_dest)
37		memcpy((void *)backup_dest, (void *)backup_src, backup_sz);
38
39	return 0;
40}
41
42int verify_sha256_digest(void)
43{
44	struct sha_region *ptr, *end;
45	u8 digest[SHA256_DIGEST_SIZE];
46	struct sha256_state sctx;
47
48	sha256_init(&sctx);
49	end = &sha_regions[sizeof(sha_regions)/sizeof(sha_regions[0])];
50	for (ptr = sha_regions; ptr < end; ptr++)
51		sha256_update(&sctx, (uint8_t *)(ptr->start), ptr->len);
52
53	sha256_final(&sctx, digest);
54
55	if (memcmp(digest, sha256_digest, sizeof(digest)))
56		return 1;
57
58	return 0;
59}
60
61void purgatory(void)
62{
63	int ret;
64
65	ret = verify_sha256_digest();
66	if (ret) {
67		/* loop forever */
68		for (;;)
69			;
70	}
71	copy_backup_region();
72}
73