1 /* 2 * purgatory: Runs between two kernels 3 * 4 * Copyright (C) 2014 Red Hat Inc. 5 * 6 * Author: 7 * Vivek Goyal <vgoyal@redhat.com> 8 * 9 * This source code is licensed under the GNU General Public License, 10 * Version 2. See the file COPYING for more details. 11 */ 12 13 #include "sha256.h" 14 #include "../boot/string.h" 15 16 struct sha_region { 17 unsigned long start; 18 unsigned long len; 19 }; 20 21 unsigned long backup_dest = 0; 22 unsigned long backup_src = 0; 23 unsigned long backup_sz = 0; 24 25 u8 sha256_digest[SHA256_DIGEST_SIZE] = { 0 }; 26 27 struct sha_region sha_regions[16] = {}; 28 29 /* 30 * On x86, second kernel requries first 640K of memory to boot. Copy 31 * first 640K to a backup region in reserved memory range so that second 32 * kernel can use first 640K. 33 */ 34 static int copy_backup_region(void) 35 { 36 if (backup_dest) 37 memcpy((void *)backup_dest, (void *)backup_src, backup_sz); 38 39 return 0; 40 } 41 42 int verify_sha256_digest(void) 43 { 44 struct sha_region *ptr, *end; 45 u8 digest[SHA256_DIGEST_SIZE]; 46 struct sha256_state sctx; 47 48 sha256_init(&sctx); 49 end = &sha_regions[sizeof(sha_regions)/sizeof(sha_regions[0])]; 50 for (ptr = sha_regions; ptr < end; ptr++) 51 sha256_update(&sctx, (uint8_t *)(ptr->start), ptr->len); 52 53 sha256_final(&sctx, digest); 54 55 if (memcmp(digest, sha256_digest, sizeof(digest))) 56 return 1; 57 58 return 0; 59 } 60 61 void purgatory(void) 62 { 63 int ret; 64 65 ret = verify_sha256_digest(); 66 if (ret) { 67 /* loop forever */ 68 for (;;) 69 ; 70 } 71 copy_backup_region(); 72 } 73