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
16 struct sha_region {
17 unsigned long start;
18 unsigned long len;
19 };
20
21 unsigned long backup_dest = 0;
22 unsigned long backup_src = 0;
23 unsigned long backup_sz = 0;
24
25 u8 sha256_digest[SHA256_DIGEST_SIZE] = { 0 };
26
27 struct 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 */
copy_backup_region(void)34 static 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
verify_sha256_digest(void)42 int 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
purgatory(void)61 void 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