1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * purgatory: Runs between two kernels
4  *
5  * Copyright (C) 2022 Huawei Technologies Co, Ltd.
6  *
7  * Author: Li Zhengyu (lizhengyu3@huawei.com)
8  *
9  */
10 
11 #include <linux/purgatory.h>
12 #include <linux/kernel.h>
13 #include <linux/string.h>
14 #include <asm/string.h>
15 
16 u8 purgatory_sha256_digest[SHA256_DIGEST_SIZE] __section(".kexec-purgatory");
17 
18 struct kexec_sha_region purgatory_sha_regions[KEXEC_SEGMENT_MAX] __section(".kexec-purgatory");
19 
verify_sha256_digest(void)20 static int verify_sha256_digest(void)
21 {
22 	struct kexec_sha_region *ptr, *end;
23 	struct sha256_state ss;
24 	u8 digest[SHA256_DIGEST_SIZE];
25 
26 	sha256_init(&ss);
27 	end = purgatory_sha_regions + ARRAY_SIZE(purgatory_sha_regions);
28 	for (ptr = purgatory_sha_regions; ptr < end; ptr++)
29 		sha256_update(&ss, (uint8_t *)(ptr->start), ptr->len);
30 	sha256_final(&ss, digest);
31 	if (memcmp(digest, purgatory_sha256_digest, sizeof(digest)) != 0)
32 		return 1;
33 	return 0;
34 }
35 
36 /* workaround for a warning with -Wmissing-prototypes */
37 void purgatory(void);
38 
purgatory(void)39 void purgatory(void)
40 {
41 	if (verify_sha256_digest())
42 		for (;;)
43 			/* loop forever */
44 			;
45 }
46