| /* |
| * This file is part of the coreboot project. |
| * |
| * Copyright (C) 2016 Google Inc. |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; version 2 of the License. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| */ |
| |
| #include <arch/early_variables.h> |
| #include <string.h> |
| #include <types.h> |
| #include <vboot/vbnv.h> |
| #include <vboot/vbnv_layout.h> |
| |
| static int vbnv_initialized CAR_GLOBAL; |
| static uint8_t vbnv[VBOOT_VBNV_BLOCK_SIZE] CAR_GLOBAL; |
| |
| /* Wrappers for accessing the variables marked as CAR_GLOBAL. */ |
| static inline int is_vbnv_initialized(void) |
| { |
| return car_get_var(vbnv_initialized); |
| } |
| |
| static inline uint8_t *vbnv_data_addr(int index) |
| { |
| uint8_t *vbnv_arr = car_get_var_ptr(vbnv); |
| |
| return &vbnv_arr[index]; |
| } |
| |
| static inline uint8_t vbnv_data(int index) |
| { |
| return *vbnv_data_addr(index); |
| } |
| |
| /* Return CRC-8 of the data, using x^8 + x^2 + x + 1 polynomial. */ |
| static uint8_t crc8_vbnv(const uint8_t *data, int len) |
| { |
| unsigned crc = 0; |
| int i, j; |
| |
| for (j = len; j; j--, data++) { |
| crc ^= (*data << 8); |
| for (i = 8; i; i--) { |
| if (crc & 0x8000) |
| crc ^= (0x1070 << 3); |
| crc <<= 1; |
| } |
| } |
| |
| return (uint8_t) (crc >> 8); |
| } |
| |
| static void reset_vbnv(uint8_t *vbnv_copy) |
| { |
| memset(vbnv_copy, 0, VBOOT_VBNV_BLOCK_SIZE); |
| } |
| |
| /* Read VBNV data into cache. */ |
| static void vbnv_setup(void) |
| { |
| if (!is_vbnv_initialized()) { |
| read_vbnv(vbnv_data_addr(0)); |
| car_set_var(vbnv_initialized, 1); |
| } |
| } |
| |
| /* Verify VBNV header and checksum. */ |
| int verify_vbnv(uint8_t *vbnv_copy) |
| { |
| return (HEADER_SIGNATURE == (vbnv_copy[HEADER_OFFSET] & HEADER_MASK)) && |
| (crc8_vbnv(vbnv_copy, CRC_OFFSET) == vbnv_copy[CRC_OFFSET]); |
| } |
| |
| /* Re-generate VBNV checksum. */ |
| void regen_vbnv_crc(uint8_t *vbnv_copy) |
| { |
| vbnv_copy[CRC_OFFSET] = crc8_vbnv(vbnv_copy, CRC_OFFSET); |
| } |
| |
| /* |
| * Read VBNV data from configured storage backend. |
| * If VBNV verification fails, reset the vbnv copy. |
| */ |
| void read_vbnv(uint8_t *vbnv_copy) |
| { |
| if (IS_ENABLED(CONFIG_VBOOT_VBNV_CMOS)) |
| read_vbnv_cmos(vbnv_copy); |
| else if (IS_ENABLED(CONFIG_VBOOT_VBNV_EC)) |
| read_vbnv_ec(vbnv_copy); |
| else if (IS_ENABLED(CONFIG_VBOOT_VBNV_FLASH)) |
| read_vbnv_flash(vbnv_copy); |
| |
| /* Check data for consistency */ |
| if (!verify_vbnv(vbnv_copy)) |
| reset_vbnv(vbnv_copy); |
| } |
| |
| /* |
| * Write VBNV data to configured storage backend. |
| * This assumes that the caller has updated the CRC already. |
| */ |
| void save_vbnv(const uint8_t *vbnv_copy) |
| { |
| if (IS_ENABLED(CONFIG_VBOOT_VBNV_CMOS)) |
| save_vbnv_cmos(vbnv_copy); |
| else if (IS_ENABLED(CONFIG_VBOOT_VBNV_EC)) |
| save_vbnv_ec(vbnv_copy); |
| else if (IS_ENABLED(CONFIG_VBOOT_VBNV_FLASH)) |
| save_vbnv_flash(vbnv_copy); |
| |
| /* Clear initialized flag to force cached data to be updated */ |
| car_set_var(vbnv_initialized, 0); |
| } |
| |
| /* Save a recovery reason into VBNV. */ |
| void set_recovery_mode_into_vbnv(int recovery_reason) |
| { |
| uint8_t vbnv_copy[VBOOT_VBNV_BLOCK_SIZE]; |
| |
| read_vbnv(vbnv_copy); |
| |
| vbnv_copy[RECOVERY_OFFSET] = recovery_reason; |
| vbnv_copy[CRC_OFFSET] = crc8_vbnv(vbnv_copy, CRC_OFFSET); |
| |
| save_vbnv(vbnv_copy); |
| } |
| |
| /* Read the recovery reason from VBNV. */ |
| int get_recovery_mode_from_vbnv(void) |
| { |
| vbnv_setup(); |
| return vbnv_data(RECOVERY_OFFSET); |
| } |
| |
| /* Read the BOOT_OPROM_NEEDED flag from VBNV. */ |
| int vboot_wants_oprom(void) |
| { |
| vbnv_setup(); |
| return (vbnv_data(BOOT_OFFSET) & BOOT_OPROM_NEEDED) ? 1 : 0; |
| } |