diff options
Diffstat (limited to 'bootloader.h')
| -rw-r--r-- | bootloader.h | 116 |
1 files changed, 108 insertions, 8 deletions
diff --git a/bootloader.h b/bootloader.h index 742a4abfb..1801705fb 100644 --- a/bootloader.h +++ b/bootloader.h @@ -17,7 +17,9 @@ #ifndef _RECOVERY_BOOTLOADER_H #define _RECOVERY_BOOTLOADER_H -/* Bootloader Message +#include <assert.h> + +/* Bootloader Message (2-KiB) * * This structure describes the content of a block in flash * that is used for recovery and the bootloader to talk to @@ -40,12 +42,10 @@ * package it is. If the value is of the format "#/#" (eg, "1/3"), * the UI will add a simple indicator of that status. * - * The slot_suffix field is used for A/B implementations where the - * bootloader does not set the androidboot.ro.boot.slot_suffix kernel - * commandline parameter. This is used by fs_mgr to mount /system and - * other partitions with the slotselect flag set in fstab. A/B - * implementations are free to use all 32 bytes and may store private - * data past the first NUL-byte in this field. + * We used to have slot_suffix field for A/B boot control metadata in + * this struct, which gets unintentionally cleared by recovery or + * uncrypt. Move it into struct bootloader_message_ab to avoid the + * issue. */ struct bootloader_message { char command[32]; @@ -58,10 +58,110 @@ struct bootloader_message { // stage string (for multistage packages) and possible future // expansion. char stage[32]; + + // The 'reserved' field used to be 224 bytes when it was initially + // carved off from the 1024-byte recovery field. Bump it up to + // 1184-byte so that the entire bootloader_message struct rounds up + // to 2048-byte. + char reserved[1184]; +}; + +/** + * We must be cautious when changing the bootloader_message struct size, + * because A/B-specific fields may end up with different offsets. + */ +#if (__STDC_VERSION__ >= 201112L) || defined(__cplusplus) +static_assert(sizeof(struct bootloader_message) == 2048, + "struct bootloader_message size changes, which may break A/B devices"); +#endif + +/** + * The A/B-specific bootloader message structure (4-KiB). + * + * We separate A/B boot control metadata from the regular bootloader + * message struct and keep it here. Everything that's A/B-specific + * stays after struct bootloader_message, which should be managed by + * the A/B-bootloader or boot control HAL. + * + * The slot_suffix field is used for A/B implementations where the + * bootloader does not set the androidboot.ro.boot.slot_suffix kernel + * commandline parameter. This is used by fs_mgr to mount /system and + * other partitions with the slotselect flag set in fstab. A/B + * implementations are free to use all 32 bytes and may store private + * data past the first NUL-byte in this field. It is encouraged, but + * not mandatory, to use 'struct bootloader_control' described below. + */ +struct bootloader_message_ab { + struct bootloader_message message; char slot_suffix[32]; - char reserved[192]; + + // Round up the entire struct to 4096-byte. + char reserved[2016]; }; +/** + * Be cautious about the struct size change, in case we put anything post + * bootloader_message_ab struct (b/29159185). + */ +#if (__STDC_VERSION__ >= 201112L) || defined(__cplusplus) +static_assert(sizeof(struct bootloader_message_ab) == 4096, + "struct bootloader_message_ab size changes"); +#endif + +#define BOOT_CTRL_MAGIC 0x42414342 /* Bootloader Control AB */ +#define BOOT_CTRL_VERSION 1 + +struct slot_metadata { + // Slot priority with 15 meaning highest priority, 1 lowest + // priority and 0 the slot is unbootable. + uint8_t priority : 4; + // Number of times left attempting to boot this slot. + uint8_t tries_remaining : 3; + // 1 if this slot has booted successfully, 0 otherwise. + uint8_t successful_boot : 1; + // 1 if this slot is corrupted from a dm-verity corruption, 0 + // otherwise. + uint8_t verity_corrupted : 1; + // Reserved for further use. + uint8_t reserved : 7; +} __attribute__((packed)); + +/* Bootloader Control AB + * + * This struct can be used to manage A/B metadata. It is designed to + * be put in the 'slot_suffix' field of the 'bootloader_message' + * structure described above. It is encouraged to use the + * 'bootloader_control' structure to store the A/B metadata, but not + * mandatory. + */ +struct bootloader_control { + // NUL terminated active slot suffix. + char slot_suffix[4]; + // Bootloader Control AB magic number (see BOOT_CTRL_MAGIC). + uint32_t magic; + // Version of struct being used (see BOOT_CTRL_VERSION). + uint8_t version; + // Number of slots being managed. + uint8_t nb_slot : 3; + // Number of times left attempting to boot recovery. + uint8_t recovery_tries_remaining : 3; + // Ensure 4-bytes alignment for slot_info field. + uint8_t reserved0[2]; + // Per-slot information. Up to 4 slots. + struct slot_metadata slot_info[4]; + // Reserved for further use. + uint8_t reserved1[8]; + // CRC32 of all 28 bytes preceding this field (little endian + // format). + uint32_t crc32_le; +} __attribute__((packed)); + +#if (__STDC_VERSION__ >= 201112L) || defined(__cplusplus) +static_assert(sizeof(struct bootloader_control) == + sizeof(((struct bootloader_message_ab *)0)->slot_suffix), + "struct bootloader_control has wrong size"); +#endif + /* Read and write the bootloader command from the "misc" partition. * These return zero on success. */ |