arch/riscv/purgatory/purgatory.c

   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
  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
  39 void purgatory(void)
  40 {
  41         if (verify_sha256_digest())
  42                 for (;;)
  43                         /* loop forever */
  44                         ;
  45 }