1 /* SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause) */
2 /*
3 * Copyright (C) International Business Machines Corp., 2006
4 * Authors: Artem Bityutskiy (Битюцкий Артём)
5 * Thomas Gleixner
6 * Frank Haverkamp
7 * Oliver Lohmann
8 * Andreas Arnez
9 *
10 * This file defines the layout of UBI headers and all the other UBI on-flash
11 * data structures.
12 */
13
14 #ifndef __UBI_MEDIA_H__
15 #define __UBI_MEDIA_H__
16
17 #include <asm/byteorder.h>
18
19 /* The version of UBI images supported by this implementation */
20 #define UBI_VERSION 1
21
22 /* The highest erase counter value supported by this implementation */
23 #define UBI_MAX_ERASECOUNTER 0x7FFFFFFF
24
25 /* The initial CRC32 value used when calculating CRC checksums */
26 #define UBI_CRC32_INIT 0xFFFFFFFFU
27
28 /* Erase counter header magic number (ASCII "UBI#") */
29 #define UBI_EC_HDR_MAGIC 0x55424923
30 /* Volume identifier header magic number (ASCII "UBI!") */
31 #define UBI_VID_HDR_MAGIC 0x55424921
32
33 /*
34 * Volume type constants used in the volume identifier header.
35 *
36 * @UBI_VID_DYNAMIC: dynamic volume
37 * @UBI_VID_STATIC: static volume
38 */
39 enum {
40 UBI_VID_DYNAMIC = 1,
41 UBI_VID_STATIC = 2
42 };
43
44 /*
45 * Volume flags used in the volume table record.
46 *
47 * @UBI_VTBL_AUTORESIZE_FLG: auto-resize this volume
48 * @UBI_VTBL_SKIP_CRC_CHECK_FLG: skip the CRC check done on a static volume at
49 * open time. Should only be set on volumes that
50 * are used by upper layers doing this kind of
51 * check. Main use-case for this flag is
52 * boot-time reduction
53 *
54 * %UBI_VTBL_AUTORESIZE_FLG flag can be set only for one volume in the volume
55 * table. UBI automatically re-sizes the volume which has this flag and makes
56 * the volume to be of largest possible size. This means that if after the
57 * initialization UBI finds out that there are available physical eraseblocks
58 * present on the device, it automatically appends all of them to the volume
59 * (the physical eraseblocks reserved for bad eraseblocks handling and other
60 * reserved physical eraseblocks are not taken). So, if there is a volume with
61 * the %UBI_VTBL_AUTORESIZE_FLG flag set, the amount of available logical
62 * eraseblocks will be zero after UBI is loaded, because all of them will be
63 * reserved for this volume. Note, the %UBI_VTBL_AUTORESIZE_FLG bit is cleared
64 * after the volume had been initialized.
65 *
66 * The auto-resize feature is useful for device production purposes. For
67 * example, different NAND flash chips may have different amount of initial bad
68 * eraseblocks, depending of particular chip instance. Manufacturers of NAND
69 * chips usually guarantee that the amount of initial bad eraseblocks does not
70 * exceed certain percent, e.g. 2%. When one creates an UBI image which will be
71 * flashed to the end devices in production, he does not know the exact amount
72 * of good physical eraseblocks the NAND chip on the device will have, but this
73 * number is required to calculate the volume sized and put them to the volume
74 * table of the UBI image. In this case, one of the volumes (e.g., the one
75 * which will store the root file system) is marked as "auto-resizable", and
76 * UBI will adjust its size on the first boot if needed.
77 *
78 * Note, first UBI reserves some amount of physical eraseblocks for bad
79 * eraseblock handling, and then re-sizes the volume, not vice-versa. This
80 * means that the pool of reserved physical eraseblocks will always be present.
81 */
82 enum {
83 UBI_VTBL_AUTORESIZE_FLG = 0x01,
84 UBI_VTBL_SKIP_CRC_CHECK_FLG = 0x02,
85 };
86
87 /*
88 * Compatibility constants used by internal volumes.
89 *
90 * @UBI_COMPAT_DELETE: delete this internal volume before anything is written
91 * to the flash
92 * @UBI_COMPAT_RO: attach this device in read-only mode
93 * @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its
94 * physical eraseblocks, don't allow the wear-leveling
95 * sub-system to move them
96 * @UBI_COMPAT_REJECT: reject this UBI image
97 */
98 enum {
99 UBI_COMPAT_DELETE = 1,
100 UBI_COMPAT_RO = 2,
101 UBI_COMPAT_PRESERVE = 4,
102 UBI_COMPAT_REJECT = 5
103 };
104
105 /* Sizes of UBI headers */
106 #define UBI_EC_HDR_SIZE sizeof(struct ubi_ec_hdr)
107 #define UBI_VID_HDR_SIZE sizeof(struct ubi_vid_hdr)
108
109 /* Sizes of UBI headers without the ending CRC */
110 #define UBI_EC_HDR_SIZE_CRC (UBI_EC_HDR_SIZE - sizeof(__be32))
111 #define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(__be32))
112
113 /**
114 * struct ubi_ec_hdr - UBI erase counter header.
115 * @magic: erase counter header magic number (%UBI_EC_HDR_MAGIC)
116 * @version: version of UBI implementation which is supposed to accept this
117 * UBI image
118 * @padding1: reserved for future, zeroes
119 * @ec: the erase counter
120 * @vid_hdr_offset: where the VID header starts
121 * @data_offset: where the user data start
122 * @image_seq: image sequence number
123 * @padding2: reserved for future, zeroes
124 * @hdr_crc: erase counter header CRC checksum
125 *
126 * The erase counter header takes 64 bytes and has a plenty of unused space for
127 * future usage. The unused fields are zeroed. The @version field is used to
128 * indicate the version of UBI implementation which is supposed to be able to
129 * work with this UBI image. If @version is greater than the current UBI
130 * version, the image is rejected. This may be useful in future if something
131 * is changed radically. This field is duplicated in the volume identifier
132 * header.
133 *
134 * The @vid_hdr_offset and @data_offset fields contain the offset of the the
135 * volume identifier header and user data, relative to the beginning of the
136 * physical eraseblock. These values have to be the same for all physical
137 * eraseblocks.
138 *
139 * The @image_seq field is used to validate a UBI image that has been prepared
140 * for a UBI device. The @image_seq value can be any value, but it must be the
141 * same on all eraseblocks. UBI will ensure that all new erase counter headers
142 * also contain this value, and will check the value when attaching the flash.
143 * One way to make use of @image_seq is to increase its value by one every time
144 * an image is flashed over an existing image, then, if the flashing does not
145 * complete, UBI will detect the error when attaching the media.
146 */
147 struct ubi_ec_hdr {
148 __be32 magic;
149 __u8 version;
150 __u8 padding1[3];
151 __be64 ec; /* Warning: the current limit is 31-bit anyway! */
152 __be32 vid_hdr_offset;
153 __be32 data_offset;
154 __be32 image_seq;
155 __u8 padding2[32];
156 __be32 hdr_crc;
157 } __packed;
158
159 /**
160 * struct ubi_vid_hdr - on-flash UBI volume identifier header.
161 * @magic: volume identifier header magic number (%UBI_VID_HDR_MAGIC)
162 * @version: UBI implementation version which is supposed to accept this UBI
163 * image (%UBI_VERSION)
164 * @vol_type: volume type (%UBI_VID_DYNAMIC or %UBI_VID_STATIC)
165 * @copy_flag: if this logical eraseblock was copied from another physical
166 * eraseblock (for wear-leveling reasons)
167 * @compat: compatibility of this volume (%0, %UBI_COMPAT_DELETE,
168 * %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT)
169 * @vol_id: ID of this volume
170 * @lnum: logical eraseblock number
171 * @padding1: reserved for future, zeroes
172 * @data_size: how many bytes of data this logical eraseblock contains
173 * @used_ebs: total number of used logical eraseblocks in this volume
174 * @data_pad: how many bytes at the end of this physical eraseblock are not
175 * used
176 * @data_crc: CRC checksum of the data stored in this logical eraseblock
177 * @padding2: reserved for future, zeroes
178 * @sqnum: sequence number
179 * @padding3: reserved for future, zeroes
180 * @hdr_crc: volume identifier header CRC checksum
181 *
182 * The @sqnum is the value of the global sequence counter at the time when this
183 * VID header was created. The global sequence counter is incremented each time
184 * UBI writes a new VID header to the flash, i.e. when it maps a logical
185 * eraseblock to a new physical eraseblock. The global sequence counter is an
186 * unsigned 64-bit integer and we assume it never overflows. The @sqnum
187 * (sequence number) is used to distinguish between older and newer versions of
188 * logical eraseblocks.
189 *
190 * There are 2 situations when there may be more than one physical eraseblock
191 * corresponding to the same logical eraseblock, i.e., having the same @vol_id
192 * and @lnum values in the volume identifier header. Suppose we have a logical
193 * eraseblock L and it is mapped to the physical eraseblock P.
194 *
195 * 1. Because UBI may erase physical eraseblocks asynchronously, the following
196 * situation is possible: L is asynchronously erased, so P is scheduled for
197 * erasure, then L is written to,i.e. mapped to another physical eraseblock P1,
198 * so P1 is written to, then an unclean reboot happens. Result - there are 2
199 * physical eraseblocks P and P1 corresponding to the same logical eraseblock
200 * L. But P1 has greater sequence number, so UBI picks P1 when it attaches the
201 * flash.
202 *
203 * 2. From time to time UBI moves logical eraseblocks to other physical
204 * eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P
205 * to P1, and an unclean reboot happens before P is physically erased, there
206 * are two physical eraseblocks P and P1 corresponding to L and UBI has to
207 * select one of them when the flash is attached. The @sqnum field says which
208 * PEB is the original (obviously P will have lower @sqnum) and the copy. But
209 * it is not enough to select the physical eraseblock with the higher sequence
210 * number, because the unclean reboot could have happen in the middle of the
211 * copying process, so the data in P is corrupted. It is also not enough to
212 * just select the physical eraseblock with lower sequence number, because the
213 * data there may be old (consider a case if more data was added to P1 after
214 * the copying). Moreover, the unclean reboot may happen when the erasure of P
215 * was just started, so it result in unstable P, which is "mostly" OK, but
216 * still has unstable bits.
217 *
218 * UBI uses the @copy_flag field to indicate that this logical eraseblock is a
219 * copy. UBI also calculates data CRC when the data is moved and stores it at
220 * the @data_crc field of the copy (P1). So when UBI needs to pick one physical
221 * eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is
222 * examined. If it is cleared, the situation is simple and the newer one is
223 * picked. If it is set, the data CRC of the copy (P1) is examined. If the CRC
224 * checksum is correct, this physical eraseblock is selected (P1). Otherwise
225 * the older one (P) is selected.
226 *
227 * There are 2 sorts of volumes in UBI: user volumes and internal volumes.
228 * Internal volumes are not seen from outside and are used for various internal
229 * UBI purposes. In this implementation there is only one internal volume - the
230 * layout volume. Internal volumes are the main mechanism of UBI extensions.
231 * For example, in future one may introduce a journal internal volume. Internal
232 * volumes have their own reserved range of IDs.
233 *
234 * The @compat field is only used for internal volumes and contains the "degree
235 * of their compatibility". It is always zero for user volumes. This field
236 * provides a mechanism to introduce UBI extensions and to be still compatible
237 * with older UBI binaries. For example, if someone introduced a journal in
238 * future, he would probably use %UBI_COMPAT_DELETE compatibility for the
239 * journal volume. And in this case, older UBI binaries, which know nothing
240 * about the journal volume, would just delete this volume and work perfectly
241 * fine. This is similar to what Ext2fs does when it is fed by an Ext3fs image
242 * - it just ignores the Ext3fs journal.
243 *
244 * The @data_crc field contains the CRC checksum of the contents of the logical
245 * eraseblock if this is a static volume. In case of dynamic volumes, it does
246 * not contain the CRC checksum as a rule. The only exception is when the
247 * data of the physical eraseblock was moved by the wear-leveling sub-system,
248 * then the wear-leveling sub-system calculates the data CRC and stores it in
249 * the @data_crc field. And of course, the @copy_flag is %in this case.
250 *
251 * The @data_size field is used only for static volumes because UBI has to know
252 * how many bytes of data are stored in this eraseblock. For dynamic volumes,
253 * this field usually contains zero. The only exception is when the data of the
254 * physical eraseblock was moved to another physical eraseblock for
255 * wear-leveling reasons. In this case, UBI calculates CRC checksum of the
256 * contents and uses both @data_crc and @data_size fields. In this case, the
257 * @data_size field contains data size.
258 *
259 * The @used_ebs field is used only for static volumes and indicates how many
260 * eraseblocks the data of the volume takes. For dynamic volumes this field is
261 * not used and always contains zero.
262 *
263 * The @data_pad is calculated when volumes are created using the alignment
264 * parameter. So, effectively, the @data_pad field reduces the size of logical
265 * eraseblocks of this volume. This is very handy when one uses block-oriented
266 * software (say, cramfs) on top of the UBI volume.
267 */
268 struct ubi_vid_hdr {
269 __be32 magic;
270 __u8 version;
271 __u8 vol_type;
272 __u8 copy_flag;
273 __u8 compat;
274 __be32 vol_id;
275 __be32 lnum;
276 __u8 padding1[4];
277 __be32 data_size;
278 __be32 used_ebs;
279 __be32 data_pad;
280 __be32 data_crc;
281 __u8 padding2[4];
282 __be64 sqnum;
283 __u8 padding3[12];
284 __be32 hdr_crc;
285 } __packed;
286
287 /* Internal UBI volumes count */
288 #define UBI_INT_VOL_COUNT 1
289
290 /*
291 * Starting ID of internal volumes: 0x7fffefff.
292 * There is reserved room for 4096 internal volumes.
293 */
294 #define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096)
295
296 /* The layout volume contains the volume table */
297
298 #define UBI_LAYOUT_VOLUME_ID UBI_INTERNAL_VOL_START
299 #define UBI_LAYOUT_VOLUME_TYPE UBI_VID_DYNAMIC
300 #define UBI_LAYOUT_VOLUME_ALIGN 1
301 #define UBI_LAYOUT_VOLUME_EBS 2
302 #define UBI_LAYOUT_VOLUME_NAME "layout volume"
303 #define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT
304
305 /* The maximum number of volumes per one UBI device */
306 #define UBI_MAX_VOLUMES 128
307
308 /* The maximum volume name length */
309 #define UBI_VOL_NAME_MAX 127
310
311 /* Size of the volume table record */
312 #define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vtbl_record)
313
314 /* Size of the volume table record without the ending CRC */
315 #define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(__be32))
316
317 /**
318 * struct ubi_vtbl_record - a record in the volume table.
319 * @reserved_pebs: how many physical eraseblocks are reserved for this volume
320 * @alignment: volume alignment
321 * @data_pad: how many bytes are unused at the end of the each physical
322 * eraseblock to satisfy the requested alignment
323 * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
324 * @upd_marker: if volume update was started but not finished
325 * @name_len: volume name length
326 * @name: the volume name
327 * @flags: volume flags (%UBI_VTBL_AUTORESIZE_FLG)
328 * @padding: reserved, zeroes
329 * @crc: a CRC32 checksum of the record
330 *
331 * The volume table records are stored in the volume table, which is stored in
332 * the layout volume. The layout volume consists of 2 logical eraseblock, each
333 * of which contains a copy of the volume table (i.e., the volume table is
334 * duplicated). The volume table is an array of &struct ubi_vtbl_record
335 * objects indexed by the volume ID.
336 *
337 * If the size of the logical eraseblock is large enough to fit
338 * %UBI_MAX_VOLUMES records, the volume table contains %UBI_MAX_VOLUMES
339 * records. Otherwise, it contains as many records as it can fit (i.e., size of
340 * logical eraseblock divided by sizeof(struct ubi_vtbl_record)).
341 *
342 * The @upd_marker flag is used to implement volume update. It is set to %1
343 * before update and set to %0 after the update. So if the update operation was
344 * interrupted, UBI knows that the volume is corrupted.
345 *
346 * The @alignment field is specified when the volume is created and cannot be
347 * later changed. It may be useful, for example, when a block-oriented file
348 * system works on top of UBI. The @data_pad field is calculated using the
349 * logical eraseblock size and @alignment. The alignment must be multiple to the
350 * minimal flash I/O unit. If @alignment is 1, all the available space of
351 * the physical eraseblocks is used.
352 *
353 * Empty records contain all zeroes and the CRC checksum of those zeroes.
354 */
355 struct ubi_vtbl_record {
356 __be32 reserved_pebs;
357 __be32 alignment;
358 __be32 data_pad;
359 __u8 vol_type;
360 __u8 upd_marker;
361 __be16 name_len;
362 __u8 name[UBI_VOL_NAME_MAX+1];
363 __u8 flags;
364 __u8 padding[23];
365 __be32 crc;
366 } __packed;
367
368 /* UBI fastmap on-flash data structures */
369
370 #define UBI_FM_SB_VOLUME_ID (UBI_LAYOUT_VOLUME_ID + 1)
371 #define UBI_FM_DATA_VOLUME_ID (UBI_LAYOUT_VOLUME_ID + 2)
372
373 /* fastmap on-flash data structure format version */
374 #define UBI_FM_FMT_VERSION 1
375
376 #define UBI_FM_SB_MAGIC 0x7B11D69F
377 #define UBI_FM_HDR_MAGIC 0xD4B82EF7
378 #define UBI_FM_VHDR_MAGIC 0xFA370ED1
379 #define UBI_FM_POOL_MAGIC 0x67AF4D08
380 #define UBI_FM_EBA_MAGIC 0xf0c040a8
381
382 /* A fastmap super block can be located between PEB 0 and
383 * UBI_FM_MAX_START */
384 #define UBI_FM_MAX_START 64
385
386 /* A fastmap can use up to UBI_FM_MAX_BLOCKS PEBs */
387 #define UBI_FM_MAX_BLOCKS 32
388
389 /* 5% of the total number of PEBs have to be scanned while attaching
390 * from a fastmap.
391 * But the size of this pool is limited to be between UBI_FM_MIN_POOL_SIZE and
392 * UBI_FM_MAX_POOL_SIZE */
393 #define UBI_FM_MIN_POOL_SIZE 8
394 #define UBI_FM_MAX_POOL_SIZE 256
395
396 /**
397 * struct ubi_fm_sb - UBI fastmap super block
398 * @magic: fastmap super block magic number (%UBI_FM_SB_MAGIC)
399 * @version: format version of this fastmap
400 * @data_crc: CRC over the fastmap data
401 * @used_blocks: number of PEBs used by this fastmap
402 * @block_loc: an array containing the location of all PEBs of the fastmap
403 * @block_ec: the erase counter of each used PEB
404 * @sqnum: highest sequence number value at the time while taking the fastmap
405 *
406 */
407 struct ubi_fm_sb {
408 __be32 magic;
409 __u8 version;
410 __u8 padding1[3];
411 __be32 data_crc;
412 __be32 used_blocks;
413 __be32 block_loc[UBI_FM_MAX_BLOCKS];
414 __be32 block_ec[UBI_FM_MAX_BLOCKS];
415 __be64 sqnum;
416 __u8 padding2[32];
417 } __packed;
418
419 /**
420 * struct ubi_fm_hdr - header of the fastmap data set
421 * @magic: fastmap header magic number (%UBI_FM_HDR_MAGIC)
422 * @free_peb_count: number of free PEBs known by this fastmap
423 * @used_peb_count: number of used PEBs known by this fastmap
424 * @scrub_peb_count: number of to be scrubbed PEBs known by this fastmap
425 * @bad_peb_count: number of bad PEBs known by this fastmap
426 * @erase_peb_count: number of bad PEBs which have to be erased
427 * @vol_count: number of UBI volumes known by this fastmap
428 */
429 struct ubi_fm_hdr {
430 __be32 magic;
431 __be32 free_peb_count;
432 __be32 used_peb_count;
433 __be32 scrub_peb_count;
434 __be32 bad_peb_count;
435 __be32 erase_peb_count;
436 __be32 vol_count;
437 __u8 padding[4];
438 } __packed;
439
440 /* struct ubi_fm_hdr is followed by two struct ubi_fm_scan_pool */
441
442 /**
443 * struct ubi_fm_scan_pool - Fastmap pool PEBs to be scanned while attaching
444 * @magic: pool magic numer (%UBI_FM_POOL_MAGIC)
445 * @size: current pool size
446 * @max_size: maximal pool size
447 * @pebs: an array containing the location of all PEBs in this pool
448 */
449 struct ubi_fm_scan_pool {
450 __be32 magic;
451 __be16 size;
452 __be16 max_size;
453 __be32 pebs[UBI_FM_MAX_POOL_SIZE];
454 __be32 padding[4];
455 } __packed;
456
457 /* ubi_fm_scan_pool is followed by nfree+nused struct ubi_fm_ec records */
458
459 /**
460 * struct ubi_fm_ec - stores the erase counter of a PEB
461 * @pnum: PEB number
462 * @ec: ec of this PEB
463 */
464 struct ubi_fm_ec {
465 __be32 pnum;
466 __be32 ec;
467 } __packed;
468
469 /**
470 * struct ubi_fm_volhdr - Fastmap volume header
471 * it identifies the start of an eba table
472 * @magic: Fastmap volume header magic number (%UBI_FM_VHDR_MAGIC)
473 * @vol_id: volume id of the fastmapped volume
474 * @vol_type: type of the fastmapped volume
475 * @data_pad: data_pad value of the fastmapped volume
476 * @used_ebs: number of used LEBs within this volume
477 * @last_eb_bytes: number of bytes used in the last LEB
478 */
479 struct ubi_fm_volhdr {
480 __be32 magic;
481 __be32 vol_id;
482 __u8 vol_type;
483 __u8 padding1[3];
484 __be32 data_pad;
485 __be32 used_ebs;
486 __be32 last_eb_bytes;
487 __u8 padding2[8];
488 } __packed;
489
490 /* struct ubi_fm_volhdr is followed by one struct ubi_fm_eba records */
491
492 /**
493 * struct ubi_fm_eba - denotes an association between a PEB and LEB
494 * @magic: EBA table magic number
495 * @reserved_pebs: number of table entries
496 * @pnum: PEB number of LEB (LEB is the index)
497 */
498 struct ubi_fm_eba {
499 __be32 magic;
500 __be32 reserved_pebs;
501 __be32 pnum[0];
502 } __packed;
503 #endif /* !__UBI_MEDIA_H__ */