arch/s390/purgatory/purgatory.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Purgatory code running between two kernels.
   4  *
   5  * Copyright IBM Corp. 2018
   6  *
   7  * Author(s): Philipp Rudo <prudo@linux.vnet.ibm.com>
   8  */
   9
  10 #include <linux/kexec.h>
  11 #include <linux/string.h>
  12 #include <crypto/sha.h>
  13 #include <asm/purgatory.h>
  14
  15 int verify_sha256_digest(void)
  16 {
  17         struct kexec_sha_region *ptr, *end;
  18         u8 digest[SHA256_DIGEST_SIZE];
  19         struct sha256_state sctx;
  20
  21         sha256_init(&sctx);
  22         end = purgatory_sha_regions + ARRAY_SIZE(purgatory_sha_regions);
  23
  24         for (ptr = purgatory_sha_regions; ptr < end; ptr++)
  25                 sha256_update(&sctx, (uint8_t *)(ptr->start), ptr->len);
  26
  27         sha256_final(&sctx, digest);
  28
  29         if (memcmp(digest, purgatory_sha256_digest, sizeof(digest)))
  30                 return 1;
  31
  32         return 0;
  33 }