1 /* 2 * Copyright (C) 2019 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 18 /** 19 * The A/B-specific bootloader message structure (4-KiB). 20 * 21 * We separate A/B boot control metadata from the regular bootloader 22 * message struct and keep it here. Everything that's A/B-specific 23 * stays after struct bootloader_message, which belongs to the vendor 24 * space of /misc partition. Also, the A/B-specific contents should be 25 * managed by the A/B-bootloader or boot control HAL. 26 * 27 * The slot_suffix field is used for A/B implementations where the 28 * bootloader does not set the androidboot.ro.boot.slot_suffix kernel 29 * commandline parameter. This is used by fs_mgr to mount /system and 30 * other partitions with the slotselect flag set in fstab. A/B 31 * implementations are free to use all 32 bytes and may store private 32 * data past the first NUL-byte in this field. It is encouraged, but 33 * not mandatory, to use 'struct bootloader_control' described below. 34 * 35 * The update_channel field is used to store the Omaha update channel 36 * if update_engine is compiled with Omaha support. 37 */ 38 struct bootloader_message_ab { 39 struct bootloader_message message; 40 char slot_suffix[32]; 41 char update_channel[128]; 42 43 // Round up the entire struct to 4096-byte. 44 char reserved[1888]; 45 }; 46 47 /** 48 * Be cautious about the struct size change, in case we put anything post 49 * bootloader_message_ab struct (b/29159185). 50 */ 51 #if (__STDC_VERSION__ >= 201112L) || defined(__cplusplus) 52 static_assert(sizeof(struct bootloader_message_ab) == 4096, 53 "struct bootloader_message_ab size changes"); 54 #endif 55 56 #define BOOT_CTRL_MAGIC 0x42414342 /* Bootloader Control AB */ 57 #define BOOT_CTRL_VERSION 1 58 59 struct slot_metadata { 60 // Slot priority with 15 meaning highest priority, 1 lowest 61 // priority and 0 the slot is unbootable. 62 uint8_t priority : 4; 63 // Number of times left attempting to boot this slot. 64 uint8_t tries_remaining : 3; 65 // 1 if this slot has booted successfully, 0 otherwise. 66 uint8_t successful_boot : 1; 67 // 1 if this slot is corrupted from a dm-verity corruption, 0 68 // otherwise. 69 uint8_t verity_corrupted : 1; 70 // Reserved for further use. 71 uint8_t reserved : 7; 72 } __attribute__((packed)); 73 74 /* Bootloader Control AB 75 * 76 * This struct can be used to manage A/B metadata. It is designed to 77 * be put in the 'slot_suffix' field of the 'bootloader_message' 78 * structure described above. It is encouraged to use the 79 * 'bootloader_control' structure to store the A/B metadata, but not 80 * mandatory. 81 */ 82 struct bootloader_control { 83 // NUL terminated active slot suffix. 84 char slot_suffix[4]; 85 // Bootloader Control AB magic number (see BOOT_CTRL_MAGIC). 86 uint32_t magic; 87 // Version of struct being used (see BOOT_CTRL_VERSION). 88 uint8_t version; 89 // Number of slots being managed. 90 uint8_t nb_slot : 3; 91 // Number of times left attempting to boot recovery. 92 uint8_t recovery_tries_remaining : 3; 93 // Status of any pending snapshot merge of dynamic partitions. 94 uint8_t merge_status : 3; 95 // Ensure 4-bytes alignment for slot_info field. 96 uint8_t reserved0[1]; 97 // Per-slot information. Up to 4 slots. 98 struct slot_metadata slot_info[4]; 99 // Reserved for further use. 100 uint8_t reserved1[8]; 101 // CRC32 of all 28 bytes preceding this field (little endian 102 // format). 103 uint32_t crc32_le; 104 } __attribute__((packed)); 105 106 #if (__STDC_VERSION__ >= 201112L) || defined(__cplusplus) 107 static_assert(sizeof(struct bootloader_control) == 108 sizeof(((struct bootloader_message_ab *)0)->slot_suffix), 109 "struct bootloader_control has wrong size"); 110 #endif 111 112