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
16u8 purgatory_sha256_digest[SHA256_DIGEST_SIZE] __section(".kexec-purgatory");
17
18struct kexec_sha_region purgatory_sha_regions[KEXEC_SEGMENT_MAX] __section(".kexec-purgatory");
19
20static 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 */
37void purgatory(void);
38
39void purgatory(void)
40{
41	if (verify_sha256_digest())
42		for (;;)
43			/* loop forever */
44			;
45}
46