arch/x86/purgatory/purgatory.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * purgatory: Runs between two kernels
   4  *
   5  * Copyright (C) 2014 Red Hat Inc.
   6  *
   7  * Author:
   8  *       Vivek Goyal <vgoyal@redhat.com>
   9  */
  10
  11 #include <linux/bug.h>
  12 #include <linux/kernel.h>
  13 #include <linux/types.h>
  14 #include <crypto/sha2.h>
  15 #include <asm/purgatory.h>
  16
  17 #include "../boot/compressed/error.h"
  18 #include "../boot/string.h"
  19
  20 u8 purgatory_sha256_digest[SHA256_DIGEST_SIZE] __section(".kexec-purgatory");
  21
  22 struct kexec_sha_region purgatory_sha_regions[KEXEC_SEGMENT_MAX] __section(".kexec-purgatory");
  23
  24 static int verify_sha256_digest(void)
  25 {
  26         struct kexec_sha_region *ptr, *end;
  27         u8 digest[SHA256_DIGEST_SIZE];
  28         struct sha256_state sctx;
  29
  30         sha256_init(&sctx);
  31         end = purgatory_sha_regions + ARRAY_SIZE(purgatory_sha_regions);
  32
  33         for (ptr = purgatory_sha_regions; ptr < end; ptr++)
  34                 sha256_update(&sctx, (uint8_t *)(ptr->start), ptr->len);
  35
  36         sha256_final(&sctx, digest);
  37
  38         if (memcmp(digest, purgatory_sha256_digest, sizeof(digest)))
  39                 return 1;
  40
  41         return 0;
  42 }
  43
  44 void purgatory(void)
  45 {
  46         int ret;
  47
  48         ret = verify_sha256_digest();
  49         if (ret) {
  50                 /* loop forever */
  51                 for (;;)
  52                         ;
  53         }
  54 }
  55
  56 /*
  57  * Defined in order to reuse memcpy() and memset() from
  58  * arch/x86/boot/compressed/string.c
  59  */
  60 void warn(const char *msg) {}