/* * 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]); } /* * 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; }