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 <linux/bug.h> 14 #include <linux/sha256.h> 15 #include <asm/purgatory.h> 16 17 #include "../boot/string.h" 18 19 unsigned long purgatory_backup_dest __section(.kexec-purgatory); 20 unsigned long purgatory_backup_src __section(.kexec-purgatory); 21 unsigned long purgatory_backup_sz __section(.kexec-purgatory); 22 23 u8 purgatory_sha256_digest[SHA256_DIGEST_SIZE] __section(.kexec-purgatory); 24 25 struct kexec_sha_region purgatory_sha_regions[KEXEC_SEGMENT_MAX] __section(.kexec-purgatory); 26 27 /* 28 * On x86, second kernel requries first 640K of memory to boot. Copy 29 * first 640K to a backup region in reserved memory range so that second 30 * kernel can use first 640K. 31 */ 32 static int copy_backup_region(void) 33 { 34 if (purgatory_backup_dest) { 35 memcpy((void *)purgatory_backup_dest, 36 (void *)purgatory_backup_src, purgatory_backup_sz); 37 } 38 return 0; 39 } 40 41 static int verify_sha256_digest(void) 42 { 43 struct kexec_sha_region *ptr, *end; 44 u8 digest[SHA256_DIGEST_SIZE]; 45 struct sha256_state sctx; 46 47 sha256_init(&sctx); 48 end = purgatory_sha_regions + ARRAY_SIZE(purgatory_sha_regions); 49 50 for (ptr = purgatory_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, purgatory_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