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linux/drivers/mtd/ubi/ubi-media.h
Quentin Schulz 6265251775 ubi: provide a way to skip CRC checks 
Some users of static UBI volumes implement their own integrity check,
thus making the volume CRC check done at open time useless. For
instance, this is the case when one use the ubiblock + dm-verity +
squashfs combination, where dm-verity already checks integrity of the
block device but this time at the block granularity instead of verifying
the whole volume.

Skipping this test drastically improves the boot-time.

Suggested-by: Boris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: Quentin Schulz <quentin.schulz@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Richard Weinberger <richard@nod.at>
2018-08-15 00:25:20 +02:00

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/* SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause) */
/*
* Copyright (C) International Business Machines Corp., 2006
* Authors: Artem Bityutskiy (Битюцкий Артём)
* Thomas Gleixner
* Frank Haverkamp
* Oliver Lohmann
* Andreas Arnez
*
* This file defines the layout of UBI headers and all the other UBI on-flash
* data structures.
*/
#ifndef __UBI_MEDIA_H__
#define __UBI_MEDIA_H__
#include <asm/byteorder.h>
/* The version of UBI images supported by this implementation */
#define UBI_VERSION 1
/* The highest erase counter value supported by this implementation */
#define UBI_MAX_ERASECOUNTER 0x7FFFFFFF
/* The initial CRC32 value used when calculating CRC checksums */
#define UBI_CRC32_INIT 0xFFFFFFFFU
/* Erase counter header magic number (ASCII "UBI#") */
#define UBI_EC_HDR_MAGIC 0x55424923
/* Volume identifier header magic number (ASCII "UBI!") */
#define UBI_VID_HDR_MAGIC 0x55424921
/*
* Volume type constants used in the volume identifier header.
*
* @UBI_VID_DYNAMIC: dynamic volume
* @UBI_VID_STATIC: static volume
*/
enum {
UBI_VID_DYNAMIC = 1,
UBI_VID_STATIC = 2
};
/*
* Volume flags used in the volume table record.
*
* @UBI_VTBL_AUTORESIZE_FLG: auto-resize this volume
* @UBI_VTBL_SKIP_CRC_CHECK_FLG: skip the CRC check done on a static volume at
* open time. Should only be set on volumes that
* are used by upper layers doing this kind of
* check. Main use-case for this flag is
* boot-time reduction
*
* %UBI_VTBL_AUTORESIZE_FLG flag can be set only for one volume in the volume
* table. UBI automatically re-sizes the volume which has this flag and makes
* the volume to be of largest possible size. This means that if after the
* initialization UBI finds out that there are available physical eraseblocks
* present on the device, it automatically appends all of them to the volume
* (the physical eraseblocks reserved for bad eraseblocks handling and other
* reserved physical eraseblocks are not taken). So, if there is a volume with
* the %UBI_VTBL_AUTORESIZE_FLG flag set, the amount of available logical
* eraseblocks will be zero after UBI is loaded, because all of them will be
* reserved for this volume. Note, the %UBI_VTBL_AUTORESIZE_FLG bit is cleared
* after the volume had been initialized.
*
* The auto-resize feature is useful for device production purposes. For
* example, different NAND flash chips may have different amount of initial bad
* eraseblocks, depending of particular chip instance. Manufacturers of NAND
* chips usually guarantee that the amount of initial bad eraseblocks does not
* exceed certain percent, e.g. 2%. When one creates an UBI image which will be
* flashed to the end devices in production, he does not know the exact amount
* of good physical eraseblocks the NAND chip on the device will have, but this
* number is required to calculate the volume sized and put them to the volume
* table of the UBI image. In this case, one of the volumes (e.g., the one
* which will store the root file system) is marked as "auto-resizable", and
* UBI will adjust its size on the first boot if needed.
*
* Note, first UBI reserves some amount of physical eraseblocks for bad
* eraseblock handling, and then re-sizes the volume, not vice-versa. This
* means that the pool of reserved physical eraseblocks will always be present.
*/
enum {
UBI_VTBL_AUTORESIZE_FLG = 0x01,
UBI_VTBL_SKIP_CRC_CHECK_FLG = 0x02,
};
/*
* Compatibility constants used by internal volumes.
*
* @UBI_COMPAT_DELETE: delete this internal volume before anything is written
* to the flash
* @UBI_COMPAT_RO: attach this device in read-only mode
* @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its
* physical eraseblocks, don't allow the wear-leveling
* sub-system to move them
* @UBI_COMPAT_REJECT: reject this UBI image
*/
enum {
UBI_COMPAT_DELETE = 1,
UBI_COMPAT_RO = 2,
UBI_COMPAT_PRESERVE = 4,
UBI_COMPAT_REJECT = 5
};
/* Sizes of UBI headers */
#define UBI_EC_HDR_SIZE sizeof(struct ubi_ec_hdr)
#define UBI_VID_HDR_SIZE sizeof(struct ubi_vid_hdr)
/* Sizes of UBI headers without the ending CRC */
#define UBI_EC_HDR_SIZE_CRC (UBI_EC_HDR_SIZE - sizeof(__be32))
#define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(__be32))
/**
* struct ubi_ec_hdr - UBI erase counter header.
* @magic: erase counter header magic number (%UBI_EC_HDR_MAGIC)
* @version: version of UBI implementation which is supposed to accept this
* UBI image
* @padding1: reserved for future, zeroes
* @ec: the erase counter
* @vid_hdr_offset: where the VID header starts
* @data_offset: where the user data start
* @image_seq: image sequence number
* @padding2: reserved for future, zeroes
* @hdr_crc: erase counter header CRC checksum
*
* The erase counter header takes 64 bytes and has a plenty of unused space for
* future usage. The unused fields are zeroed. The @version field is used to
* indicate the version of UBI implementation which is supposed to be able to
* work with this UBI image. If @version is greater than the current UBI
* version, the image is rejected. This may be useful in future if something
* is changed radically. This field is duplicated in the volume identifier
* header.
*
* The @vid_hdr_offset and @data_offset fields contain the offset of the the
* volume identifier header and user data, relative to the beginning of the
* physical eraseblock. These values have to be the same for all physical
* eraseblocks.
*
* The @image_seq field is used to validate a UBI image that has been prepared
* for a UBI device. The @image_seq value can be any value, but it must be the
* same on all eraseblocks. UBI will ensure that all new erase counter headers
* also contain this value, and will check the value when attaching the flash.
* One way to make use of @image_seq is to increase its value by one every time
* an image is flashed over an existing image, then, if the flashing does not
* complete, UBI will detect the error when attaching the media.
*/
struct ubi_ec_hdr {
__be32 magic;
__u8 version;
__u8 padding1[3];
__be64 ec; /* Warning: the current limit is 31-bit anyway! */
__be32 vid_hdr_offset;
__be32 data_offset;
__be32 image_seq;
__u8 padding2[32];
__be32 hdr_crc;
} __packed;
/**
* struct ubi_vid_hdr - on-flash UBI volume identifier header.
* @magic: volume identifier header magic number (%UBI_VID_HDR_MAGIC)
* @version: UBI implementation version which is supposed to accept this UBI
* image (%UBI_VERSION)
* @vol_type: volume type (%UBI_VID_DYNAMIC or %UBI_VID_STATIC)
* @copy_flag: if this logical eraseblock was copied from another physical
* eraseblock (for wear-leveling reasons)
* @compat: compatibility of this volume (%0, %UBI_COMPAT_DELETE,
* %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT)
* @vol_id: ID of this volume
* @lnum: logical eraseblock number
* @padding1: reserved for future, zeroes
* @data_size: how many bytes of data this logical eraseblock contains
* @used_ebs: total number of used logical eraseblocks in this volume
* @data_pad: how many bytes at the end of this physical eraseblock are not
* used
* @data_crc: CRC checksum of the data stored in this logical eraseblock
* @padding2: reserved for future, zeroes
* @sqnum: sequence number
* @padding3: reserved for future, zeroes
* @hdr_crc: volume identifier header CRC checksum
*
* The @sqnum is the value of the global sequence counter at the time when this
* VID header was created. The global sequence counter is incremented each time
* UBI writes a new VID header to the flash, i.e. when it maps a logical
* eraseblock to a new physical eraseblock. The global sequence counter is an
* unsigned 64-bit integer and we assume it never overflows. The @sqnum
* (sequence number) is used to distinguish between older and newer versions of
* logical eraseblocks.
*
* There are 2 situations when there may be more than one physical eraseblock
* corresponding to the same logical eraseblock, i.e., having the same @vol_id
* and @lnum values in the volume identifier header. Suppose we have a logical
* eraseblock L and it is mapped to the physical eraseblock P.
*
* 1. Because UBI may erase physical eraseblocks asynchronously, the following
* situation is possible: L is asynchronously erased, so P is scheduled for
* erasure, then L is written to,i.e. mapped to another physical eraseblock P1,
* so P1 is written to, then an unclean reboot happens. Result - there are 2
* physical eraseblocks P and P1 corresponding to the same logical eraseblock
* L. But P1 has greater sequence number, so UBI picks P1 when it attaches the
* flash.
*
* 2. From time to time UBI moves logical eraseblocks to other physical
* eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P
* to P1, and an unclean reboot happens before P is physically erased, there
* are two physical eraseblocks P and P1 corresponding to L and UBI has to
* select one of them when the flash is attached. The @sqnum field says which
* PEB is the original (obviously P will have lower @sqnum) and the copy. But
* it is not enough to select the physical eraseblock with the higher sequence
* number, because the unclean reboot could have happen in the middle of the
* copying process, so the data in P is corrupted. It is also not enough to
* just select the physical eraseblock with lower sequence number, because the
* data there may be old (consider a case if more data was added to P1 after
* the copying). Moreover, the unclean reboot may happen when the erasure of P
* was just started, so it result in unstable P, which is "mostly" OK, but
* still has unstable bits.
*
* UBI uses the @copy_flag field to indicate that this logical eraseblock is a
* copy. UBI also calculates data CRC when the data is moved and stores it at
* the @data_crc field of the copy (P1). So when UBI needs to pick one physical
* eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is
* examined. If it is cleared, the situation is simple and the newer one is
* picked. If it is set, the data CRC of the copy (P1) is examined. If the CRC
* checksum is correct, this physical eraseblock is selected (P1). Otherwise
* the older one (P) is selected.
*
* There are 2 sorts of volumes in UBI: user volumes and internal volumes.
* Internal volumes are not seen from outside and are used for various internal
* UBI purposes. In this implementation there is only one internal volume - the
* layout volume. Internal volumes are the main mechanism of UBI extensions.
* For example, in future one may introduce a journal internal volume. Internal
* volumes have their own reserved range of IDs.
*
* The @compat field is only used for internal volumes and contains the "degree
* of their compatibility". It is always zero for user volumes. This field
* provides a mechanism to introduce UBI extensions and to be still compatible
* with older UBI binaries. For example, if someone introduced a journal in
* future, he would probably use %UBI_COMPAT_DELETE compatibility for the
* journal volume. And in this case, older UBI binaries, which know nothing
* about the journal volume, would just delete this volume and work perfectly
* fine. This is similar to what Ext2fs does when it is fed by an Ext3fs image
* - it just ignores the Ext3fs journal.
*
* The @data_crc field contains the CRC checksum of the contents of the logical
* eraseblock if this is a static volume. In case of dynamic volumes, it does
* not contain the CRC checksum as a rule. The only exception is when the
* data of the physical eraseblock was moved by the wear-leveling sub-system,
* then the wear-leveling sub-system calculates the data CRC and stores it in
* the @data_crc field. And of course, the @copy_flag is %in this case.
*
* The @data_size field is used only for static volumes because UBI has to know
* how many bytes of data are stored in this eraseblock. For dynamic volumes,
* this field usually contains zero. The only exception is when the data of the
* physical eraseblock was moved to another physical eraseblock for
* wear-leveling reasons. In this case, UBI calculates CRC checksum of the
* contents and uses both @data_crc and @data_size fields. In this case, the
* @data_size field contains data size.
*
* The @used_ebs field is used only for static volumes and indicates how many
* eraseblocks the data of the volume takes. For dynamic volumes this field is
* not used and always contains zero.
*
* The @data_pad is calculated when volumes are created using the alignment
* parameter. So, effectively, the @data_pad field reduces the size of logical
* eraseblocks of this volume. This is very handy when one uses block-oriented
* software (say, cramfs) on top of the UBI volume.
*/
struct ubi_vid_hdr {
__be32 magic;
__u8 version;
__u8 vol_type;
__u8 copy_flag;
__u8 compat;
__be32 vol_id;
__be32 lnum;
__u8 padding1[4];
__be32 data_size;
__be32 used_ebs;
__be32 data_pad;
__be32 data_crc;
__u8 padding2[4];
__be64 sqnum;
__u8 padding3[12];
__be32 hdr_crc;
} __packed;
/* Internal UBI volumes count */
#define UBI_INT_VOL_COUNT 1
/*
* Starting ID of internal volumes: 0x7fffefff.
* There is reserved room for 4096 internal volumes.
*/
#define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096)
/* The layout volume contains the volume table */
#define UBI_LAYOUT_VOLUME_ID UBI_INTERNAL_VOL_START
#define UBI_LAYOUT_VOLUME_TYPE UBI_VID_DYNAMIC
#define UBI_LAYOUT_VOLUME_ALIGN 1
#define UBI_LAYOUT_VOLUME_EBS 2
#define UBI_LAYOUT_VOLUME_NAME "layout volume"
#define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT
/* The maximum number of volumes per one UBI device */
#define UBI_MAX_VOLUMES 128
/* The maximum volume name length */
#define UBI_VOL_NAME_MAX 127
/* Size of the volume table record */
#define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vtbl_record)
/* Size of the volume table record without the ending CRC */
#define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(__be32))
/**
* struct ubi_vtbl_record - a record in the volume table.
* @reserved_pebs: how many physical eraseblocks are reserved for this volume
* @alignment: volume alignment
* @data_pad: how many bytes are unused at the end of the each physical
* eraseblock to satisfy the requested alignment
* @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
* @upd_marker: if volume update was started but not finished
* @name_len: volume name length
* @name: the volume name
* @flags: volume flags (%UBI_VTBL_AUTORESIZE_FLG)
* @padding: reserved, zeroes
* @crc: a CRC32 checksum of the record
*
* The volume table records are stored in the volume table, which is stored in
* the layout volume. The layout volume consists of 2 logical eraseblock, each
* of which contains a copy of the volume table (i.e., the volume table is
* duplicated). The volume table is an array of &struct ubi_vtbl_record
* objects indexed by the volume ID.
*
* If the size of the logical eraseblock is large enough to fit
* %UBI_MAX_VOLUMES records, the volume table contains %UBI_MAX_VOLUMES
* records. Otherwise, it contains as many records as it can fit (i.e., size of
* logical eraseblock divided by sizeof(struct ubi_vtbl_record)).
*
* The @upd_marker flag is used to implement volume update. It is set to %1
* before update and set to %0 after the update. So if the update operation was
* interrupted, UBI knows that the volume is corrupted.
*
* The @alignment field is specified when the volume is created and cannot be
* later changed. It may be useful, for example, when a block-oriented file
* system works on top of UBI. The @data_pad field is calculated using the
* logical eraseblock size and @alignment. The alignment must be multiple to the
* minimal flash I/O unit. If @alignment is 1, all the available space of
* the physical eraseblocks is used.
*
* Empty records contain all zeroes and the CRC checksum of those zeroes.
*/
struct ubi_vtbl_record {
__be32 reserved_pebs;
__be32 alignment;
__be32 data_pad;
__u8 vol_type;
__u8 upd_marker;
__be16 name_len;
__u8 name[UBI_VOL_NAME_MAX+1];
__u8 flags;
__u8 padding[23];
__be32 crc;
} __packed;
/* UBI fastmap on-flash data structures */
#define UBI_FM_SB_VOLUME_ID (UBI_LAYOUT_VOLUME_ID + 1)
#define UBI_FM_DATA_VOLUME_ID (UBI_LAYOUT_VOLUME_ID + 2)
/* fastmap on-flash data structure format version */
#define UBI_FM_FMT_VERSION 1
#define UBI_FM_SB_MAGIC 0x7B11D69F
#define UBI_FM_HDR_MAGIC 0xD4B82EF7
#define UBI_FM_VHDR_MAGIC 0xFA370ED1
#define UBI_FM_POOL_MAGIC 0x67AF4D08
#define UBI_FM_EBA_MAGIC 0xf0c040a8
/* A fastmap super block can be located between PEB 0 and
* UBI_FM_MAX_START */
#define UBI_FM_MAX_START 64
/* A fastmap can use up to UBI_FM_MAX_BLOCKS PEBs */
#define UBI_FM_MAX_BLOCKS 32
/* 5% of the total number of PEBs have to be scanned while attaching
* from a fastmap.
* But the size of this pool is limited to be between UBI_FM_MIN_POOL_SIZE and
* UBI_FM_MAX_POOL_SIZE */
#define UBI_FM_MIN_POOL_SIZE 8
#define UBI_FM_MAX_POOL_SIZE 256
/**
* struct ubi_fm_sb - UBI fastmap super block
* @magic: fastmap super block magic number (%UBI_FM_SB_MAGIC)
* @version: format version of this fastmap
* @data_crc: CRC over the fastmap data
* @used_blocks: number of PEBs used by this fastmap
* @block_loc: an array containing the location of all PEBs of the fastmap
* @block_ec: the erase counter of each used PEB
* @sqnum: highest sequence number value at the time while taking the fastmap
*
*/
struct ubi_fm_sb {
__be32 magic;
__u8 version;
__u8 padding1[3];
__be32 data_crc;
__be32 used_blocks;
__be32 block_loc[UBI_FM_MAX_BLOCKS];
__be32 block_ec[UBI_FM_MAX_BLOCKS];
__be64 sqnum;
__u8 padding2[32];
} __packed;
/**
* struct ubi_fm_hdr - header of the fastmap data set
* @magic: fastmap header magic number (%UBI_FM_HDR_MAGIC)
* @free_peb_count: number of free PEBs known by this fastmap
* @used_peb_count: number of used PEBs known by this fastmap
* @scrub_peb_count: number of to be scrubbed PEBs known by this fastmap
* @bad_peb_count: number of bad PEBs known by this fastmap
* @erase_peb_count: number of bad PEBs which have to be erased
* @vol_count: number of UBI volumes known by this fastmap
*/
struct ubi_fm_hdr {
__be32 magic;
__be32 free_peb_count;
__be32 used_peb_count;
__be32 scrub_peb_count;
__be32 bad_peb_count;
__be32 erase_peb_count;
__be32 vol_count;
__u8 padding[4];
} __packed;
/* struct ubi_fm_hdr is followed by two struct ubi_fm_scan_pool */
/**
* struct ubi_fm_scan_pool - Fastmap pool PEBs to be scanned while attaching
* @magic: pool magic numer (%UBI_FM_POOL_MAGIC)
* @size: current pool size
* @max_size: maximal pool size
* @pebs: an array containing the location of all PEBs in this pool
*/
struct ubi_fm_scan_pool {
__be32 magic;
__be16 size;
__be16 max_size;
__be32 pebs[UBI_FM_MAX_POOL_SIZE];
__be32 padding[4];
} __packed;
/* ubi_fm_scan_pool is followed by nfree+nused struct ubi_fm_ec records */
/**
* struct ubi_fm_ec - stores the erase counter of a PEB
* @pnum: PEB number
* @ec: ec of this PEB
*/
struct ubi_fm_ec {
__be32 pnum;
__be32 ec;
} __packed;
/**
* struct ubi_fm_volhdr - Fastmap volume header
* it identifies the start of an eba table
* @magic: Fastmap volume header magic number (%UBI_FM_VHDR_MAGIC)
* @vol_id: volume id of the fastmapped volume
* @vol_type: type of the fastmapped volume
* @data_pad: data_pad value of the fastmapped volume
* @used_ebs: number of used LEBs within this volume
* @last_eb_bytes: number of bytes used in the last LEB
*/
struct ubi_fm_volhdr {
__be32 magic;
__be32 vol_id;
__u8 vol_type;
__u8 padding1[3];
__be32 data_pad;
__be32 used_ebs;
__be32 last_eb_bytes;
__u8 padding2[8];
} __packed;
/* struct ubi_fm_volhdr is followed by one struct ubi_fm_eba records */
/**
* struct ubi_fm_eba - denotes an association between a PEB and LEB
* @magic: EBA table magic number
* @reserved_pebs: number of table entries
* @pnum: PEB number of LEB (LEB is the index)
*/
struct ubi_fm_eba {
__be32 magic;
__be32 reserved_pebs;
__be32 pnum[0];
} __packed;
#endif /* !__UBI_MEDIA_H__ */
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