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1 /* SPDX-License-Identifier: GPL-2.0+ */
2 /*
3  * Copyright (c) International Business Machines Corp., 2006
4  *
5  * Authors: Artem Bityutskiy (Битюцкий Артём)
6  *          Thomas Gleixner
7  *          Frank Haverkamp
8  *          Oliver Lohmann
9  *          Andreas Arnez
10  */
11 
12 /*
13  * This file defines the layout of UBI headers and all the other UBI on-flash
14  * data structures.
15  */
16 
17 #ifndef __UBI_MEDIA_H__
18 #define __UBI_MEDIA_H__
19 
20 #include <asm/byteorder.h>
21 
22 /* The version of UBI images supported by this implementation */
23 #define UBI_VERSION 1
24 
25 /* The highest erase counter value supported by this implementation */
26 #define UBI_MAX_ERASECOUNTER 0x7FFFFFFF
27 
28 /* The initial CRC32 value used when calculating CRC checksums */
29 #define UBI_CRC32_INIT 0xFFFFFFFFU
30 
31 /* Erase counter header magic number (ASCII "UBI#") */
32 #define UBI_EC_HDR_MAGIC  0x55424923
33 /* Volume identifier header magic number (ASCII "UBI!") */
34 #define UBI_VID_HDR_MAGIC 0x55424921
35 
36 /*
37  * Volume type constants used in the volume identifier header.
38  *
39  * @UBI_VID_DYNAMIC: dynamic volume
40  * @UBI_VID_STATIC: static volume
41  */
42 enum {
43 	UBI_VID_DYNAMIC = 1,
44 	UBI_VID_STATIC  = 2
45 };
46 
47 /*
48  * Volume flags used in the volume table record.
49  *
50  * @UBI_VTBL_AUTORESIZE_FLG: auto-resize this volume
51  *
52  * %UBI_VTBL_AUTORESIZE_FLG flag can be set only for one volume in the volume
53  * table. UBI automatically re-sizes the volume which has this flag and makes
54  * the volume to be of largest possible size. This means that if after the
55  * initialization UBI finds out that there are available physical eraseblocks
56  * present on the device, it automatically appends all of them to the volume
57  * (the physical eraseblocks reserved for bad eraseblocks handling and other
58  * reserved physical eraseblocks are not taken). So, if there is a volume with
59  * the %UBI_VTBL_AUTORESIZE_FLG flag set, the amount of available logical
60  * eraseblocks will be zero after UBI is loaded, because all of them will be
61  * reserved for this volume. Note, the %UBI_VTBL_AUTORESIZE_FLG bit is cleared
62  * after the volume had been initialized.
63  *
64  * The auto-resize feature is useful for device production purposes. For
65  * example, different NAND flash chips may have different amount of initial bad
66  * eraseblocks, depending of particular chip instance. Manufacturers of NAND
67  * chips usually guarantee that the amount of initial bad eraseblocks does not
68  * exceed certain percent, e.g. 2%. When one creates an UBI image which will be
69  * flashed to the end devices in production, he does not know the exact amount
70  * of good physical eraseblocks the NAND chip on the device will have, but this
71  * number is required to calculate the volume sized and put them to the volume
72  * table of the UBI image. In this case, one of the volumes (e.g., the one
73  * which will store the root file system) is marked as "auto-resizable", and
74  * UBI will adjust its size on the first boot if needed.
75  *
76  * Note, first UBI reserves some amount of physical eraseblocks for bad
77  * eraseblock handling, and then re-sizes the volume, not vice-versa. This
78  * means that the pool of reserved physical eraseblocks will always be present.
79  */
80 enum {
81 	UBI_VTBL_AUTORESIZE_FLG = 0x01,
82 };
83 
84 /*
85  * Compatibility constants used by internal volumes.
86  *
87  * @UBI_COMPAT_DELETE: delete this internal volume before anything is written
88  *                     to the flash
89  * @UBI_COMPAT_RO: attach this device in read-only mode
90  * @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its
91  *                       physical eraseblocks, don't allow the wear-leveling
92  *                       sub-system to move them
93  * @UBI_COMPAT_REJECT: reject this UBI image
94  */
95 enum {
96 	UBI_COMPAT_DELETE   = 1,
97 	UBI_COMPAT_RO       = 2,
98 	UBI_COMPAT_PRESERVE = 4,
99 	UBI_COMPAT_REJECT   = 5
100 };
101 
102 /* Sizes of UBI headers */
103 #define UBI_EC_HDR_SIZE  sizeof(struct ubi_ec_hdr)
104 #define UBI_VID_HDR_SIZE sizeof(struct ubi_vid_hdr)
105 
106 /* Sizes of UBI headers without the ending CRC */
107 #define UBI_EC_HDR_SIZE_CRC  (UBI_EC_HDR_SIZE  - sizeof(__be32))
108 #define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(__be32))
109 
110 /**
111  * struct ubi_ec_hdr - UBI erase counter header.
112  * @magic: erase counter header magic number (%UBI_EC_HDR_MAGIC)
113  * @version: version of UBI implementation which is supposed to accept this
114  *           UBI image
115  * @padding1: reserved for future, zeroes
116  * @ec: the erase counter
117  * @vid_hdr_offset: where the VID header starts
118  * @data_offset: where the user data start
119  * @image_seq: image sequence number
120  * @padding2: reserved for future, zeroes
121  * @hdr_crc: erase counter header CRC checksum
122  *
123  * The erase counter header takes 64 bytes and has a plenty of unused space for
124  * future usage. The unused fields are zeroed. The @version field is used to
125  * indicate the version of UBI implementation which is supposed to be able to
126  * work with this UBI image. If @version is greater than the current UBI
127  * version, the image is rejected. This may be useful in future if something
128  * is changed radically. This field is duplicated in the volume identifier
129  * header.
130  *
131  * The @vid_hdr_offset and @data_offset fields contain the offset of the the
132  * volume identifier header and user data, relative to the beginning of the
133  * physical eraseblock. These values have to be the same for all physical
134  * eraseblocks.
135  *
136  * The @image_seq field is used to validate a UBI image that has been prepared
137  * for a UBI device. The @image_seq value can be any value, but it must be the
138  * same on all eraseblocks. UBI will ensure that all new erase counter headers
139  * also contain this value, and will check the value when attaching the flash.
140  * One way to make use of @image_seq is to increase its value by one every time
141  * an image is flashed over an existing image, then, if the flashing does not
142  * complete, UBI will detect the error when attaching the media.
143  */
144 struct ubi_ec_hdr {
145 	__be32  magic;
146 	__u8    version;
147 	__u8    padding1[3];
148 	__be64  ec; /* Warning: the current limit is 31-bit anyway! */
149 	__be32  vid_hdr_offset;
150 	__be32  data_offset;
151 	__be32  image_seq;
152 	__u8    padding2[32];
153 	__be32  hdr_crc;
154 } __packed;
155 
156 /**
157  * struct ubi_vid_hdr - on-flash UBI volume identifier header.
158  * @magic: volume identifier header magic number (%UBI_VID_HDR_MAGIC)
159  * @version: UBI implementation version which is supposed to accept this UBI
160  *           image (%UBI_VERSION)
161  * @vol_type: volume type (%UBI_VID_DYNAMIC or %UBI_VID_STATIC)
162  * @copy_flag: if this logical eraseblock was copied from another physical
163  *             eraseblock (for wear-leveling reasons)
164  * @compat: compatibility of this volume (%0, %UBI_COMPAT_DELETE,
165  *          %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT)
166  * @vol_id: ID of this volume
167  * @lnum: logical eraseblock number
168  * @padding1: reserved for future, zeroes
169  * @data_size: how many bytes of data this logical eraseblock contains
170  * @used_ebs: total number of used logical eraseblocks in this volume
171  * @data_pad: how many bytes at the end of this physical eraseblock are not
172  *            used
173  * @data_crc: CRC checksum of the data stored in this logical eraseblock
174  * @padding2: reserved for future, zeroes
175  * @sqnum: sequence number
176  * @padding3: reserved for future, zeroes
177  * @hdr_crc: volume identifier header CRC checksum
178  *
179  * The @sqnum is the value of the global sequence counter at the time when this
180  * VID header was created. The global sequence counter is incremented each time
181  * UBI writes a new VID header to the flash, i.e. when it maps a logical
182  * eraseblock to a new physical eraseblock. The global sequence counter is an
183  * unsigned 64-bit integer and we assume it never overflows. The @sqnum
184  * (sequence number) is used to distinguish between older and newer versions of
185  * logical eraseblocks.
186  *
187  * There are 2 situations when there may be more than one physical eraseblock
188  * corresponding to the same logical eraseblock, i.e., having the same @vol_id
189  * and @lnum values in the volume identifier header. Suppose we have a logical
190  * eraseblock L and it is mapped to the physical eraseblock P.
191  *
192  * 1. Because UBI may erase physical eraseblocks asynchronously, the following
193  * situation is possible: L is asynchronously erased, so P is scheduled for
194  * erasure, then L is written to,i.e. mapped to another physical eraseblock P1,
195  * so P1 is written to, then an unclean reboot happens. Result - there are 2
196  * physical eraseblocks P and P1 corresponding to the same logical eraseblock
197  * L. But P1 has greater sequence number, so UBI picks P1 when it attaches the
198  * flash.
199  *
200  * 2. From time to time UBI moves logical eraseblocks to other physical
201  * eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P
202  * to P1, and an unclean reboot happens before P is physically erased, there
203  * are two physical eraseblocks P and P1 corresponding to L and UBI has to
204  * select one of them when the flash is attached. The @sqnum field says which
205  * PEB is the original (obviously P will have lower @sqnum) and the copy. But
206  * it is not enough to select the physical eraseblock with the higher sequence
207  * number, because the unclean reboot could have happen in the middle of the
208  * copying process, so the data in P is corrupted. It is also not enough to
209  * just select the physical eraseblock with lower sequence number, because the
210  * data there may be old (consider a case if more data was added to P1 after
211  * the copying). Moreover, the unclean reboot may happen when the erasure of P
212  * was just started, so it result in unstable P, which is "mostly" OK, but
213  * still has unstable bits.
214  *
215  * UBI uses the @copy_flag field to indicate that this logical eraseblock is a
216  * copy. UBI also calculates data CRC when the data is moved and stores it at
217  * the @data_crc field of the copy (P1). So when UBI needs to pick one physical
218  * eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is
219  * examined. If it is cleared, the situation* is simple and the newer one is
220  * picked. If it is set, the data CRC of the copy (P1) is examined. If the CRC
221  * checksum is correct, this physical eraseblock is selected (P1). Otherwise
222  * the older one (P) is selected.
223  *
224  * There are 2 sorts of volumes in UBI: user volumes and internal volumes.
225  * Internal volumes are not seen from outside and are used for various internal
226  * UBI purposes. In this implementation there is only one internal volume - the
227  * layout volume. Internal volumes are the main mechanism of UBI extensions.
228  * For example, in future one may introduce a journal internal volume. Internal
229  * volumes have their own reserved range of IDs.
230  *
231  * The @compat field is only used for internal volumes and contains the "degree
232  * of their compatibility". It is always zero for user volumes. This field
233  * provides a mechanism to introduce UBI extensions and to be still compatible
234  * with older UBI binaries. For example, if someone introduced a journal in
235  * future, he would probably use %UBI_COMPAT_DELETE compatibility for the
236  * journal volume.  And in this case, older UBI binaries, which know nothing
237  * about the journal volume, would just delete this volume and work perfectly
238  * fine. This is similar to what Ext2fs does when it is fed by an Ext3fs image
239  * - it just ignores the Ext3fs journal.
240  *
241  * The @data_crc field contains the CRC checksum of the contents of the logical
242  * eraseblock if this is a static volume. In case of dynamic volumes, it does
243  * not contain the CRC checksum as a rule. The only exception is when the
244  * data of the physical eraseblock was moved by the wear-leveling sub-system,
245  * then the wear-leveling sub-system calculates the data CRC and stores it in
246  * the @data_crc field. And of course, the @copy_flag is %in this case.
247  *
248  * The @data_size field is used only for static volumes because UBI has to know
249  * how many bytes of data are stored in this eraseblock. For dynamic volumes,
250  * this field usually contains zero. The only exception is when the data of the
251  * physical eraseblock was moved to another physical eraseblock for
252  * wear-leveling reasons. In this case, UBI calculates CRC checksum of the
253  * contents and uses both @data_crc and @data_size fields. In this case, the
254  * @data_size field contains data size.
255  *
256  * The @used_ebs field is used only for static volumes and indicates how many
257  * eraseblocks the data of the volume takes. For dynamic volumes this field is
258  * not used and always contains zero.
259  *
260  * The @data_pad is calculated when volumes are created using the alignment
261  * parameter. So, effectively, the @data_pad field reduces the size of logical
262  * eraseblocks of this volume. This is very handy when one uses block-oriented
263  * software (say, cramfs) on top of the UBI volume.
264  */
265 struct ubi_vid_hdr {
266 	__be32  magic;
267 	__u8    version;
268 	__u8    vol_type;
269 	__u8    copy_flag;
270 	__u8    compat;
271 	__be32  vol_id;
272 	__be32  lnum;
273 	__u8    padding1[4];
274 	__be32  data_size;
275 	__be32  used_ebs;
276 	__be32  data_pad;
277 	__be32  data_crc;
278 	__u8    padding2[4];
279 	__be64  sqnum;
280 	__u8    padding3[12];
281 	__be32  hdr_crc;
282 } __packed;
283 
284 /* Internal UBI volumes count */
285 #define UBI_INT_VOL_COUNT 1
286 
287 /*
288  * Starting ID of internal volumes: 0x7fffefff.
289  * There is reserved room for 4096 internal volumes.
290  */
291 #define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096)
292 
293 /* The layout volume contains the volume table */
294 
295 #define UBI_LAYOUT_VOLUME_ID     UBI_INTERNAL_VOL_START
296 #define UBI_LAYOUT_VOLUME_TYPE   UBI_VID_DYNAMIC
297 #define UBI_LAYOUT_VOLUME_ALIGN  1
298 #define UBI_LAYOUT_VOLUME_EBS    2
299 #define UBI_LAYOUT_VOLUME_NAME   "layout volume"
300 #define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT
301 
302 /* The maximum number of volumes per one UBI device */
303 #define UBI_MAX_VOLUMES 128
304 
305 /* The maximum volume name length */
306 #define UBI_VOL_NAME_MAX 127
307 
308 /* Size of the volume table record */
309 #define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vtbl_record)
310 
311 /* Size of the volume table record without the ending CRC */
312 #define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(__be32))
313 
314 /**
315  * struct ubi_vtbl_record - a record in the volume table.
316  * @reserved_pebs: how many physical eraseblocks are reserved for this volume
317  * @alignment: volume alignment
318  * @data_pad: how many bytes are unused at the end of the each physical
319  * eraseblock to satisfy the requested alignment
320  * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
321  * @upd_marker: if volume update was started but not finished
322  * @name_len: volume name length
323  * @name: the volume name
324  * @flags: volume flags (%UBI_VTBL_AUTORESIZE_FLG)
325  * @padding: reserved, zeroes
326  * @crc: a CRC32 checksum of the record
327  *
328  * The volume table records are stored in the volume table, which is stored in
329  * the layout volume. The layout volume consists of 2 logical eraseblock, each
330  * of which contains a copy of the volume table (i.e., the volume table is
331  * duplicated). The volume table is an array of &struct ubi_vtbl_record
332  * objects indexed by the volume ID.
333  *
334  * If the size of the logical eraseblock is large enough to fit
335  * %UBI_MAX_VOLUMES records, the volume table contains %UBI_MAX_VOLUMES
336  * records. Otherwise, it contains as many records as it can fit (i.e., size of
337  * logical eraseblock divided by sizeof(struct ubi_vtbl_record)).
338  *
339  * The @upd_marker flag is used to implement volume update. It is set to %1
340  * before update and set to %0 after the update. So if the update operation was
341  * interrupted, UBI knows that the volume is corrupted.
342  *
343  * The @alignment field is specified when the volume is created and cannot be
344  * later changed. It may be useful, for example, when a block-oriented file
345  * system works on top of UBI. The @data_pad field is calculated using the
346  * logical eraseblock size and @alignment. The alignment must be multiple to the
347  * minimal flash I/O unit. If @alignment is 1, all the available space of
348  * the physical eraseblocks is used.
349  *
350  * Empty records contain all zeroes and the CRC checksum of those zeroes.
351  */
352 struct ubi_vtbl_record {
353 	__be32  reserved_pebs;
354 	__be32  alignment;
355 	__be32  data_pad;
356 	__u8    vol_type;
357 	__u8    upd_marker;
358 	__be16  name_len;
359 #ifndef __UBOOT__
360 	__u8    name[UBI_VOL_NAME_MAX+1];
361 #else
362 	char    name[UBI_VOL_NAME_MAX+1];
363 #endif
364 	__u8    flags;
365 	__u8    padding[23];
366 	__be32  crc;
367 } __packed;
368 
369 /* UBI fastmap on-flash data structures */
370 
371 #define UBI_FM_SB_VOLUME_ID	(UBI_LAYOUT_VOLUME_ID + 1)
372 #define UBI_FM_DATA_VOLUME_ID	(UBI_LAYOUT_VOLUME_ID + 2)
373 
374 /* fastmap on-flash data structure format version */
375 #define UBI_FM_FMT_VERSION	1
376 
377 #define UBI_FM_SB_MAGIC		0x7B11D69F
378 #define UBI_FM_HDR_MAGIC	0xD4B82EF7
379 #define UBI_FM_VHDR_MAGIC	0xFA370ED1
380 #define UBI_FM_POOL_MAGIC	0x67AF4D08
381 #define UBI_FM_EBA_MAGIC	0xf0c040a8
382 
383 /* A fastmap supber block can be located between PEB 0 and
384  * UBI_FM_MAX_START */
385 #define UBI_FM_MAX_START	64
386 
387 /* A fastmap can use up to UBI_FM_MAX_BLOCKS PEBs */
388 #define UBI_FM_MAX_BLOCKS	32
389 
390 /* 5% of the total number of PEBs have to be scanned while attaching
391  * from a fastmap.
392  * But the size of this pool is limited to be between UBI_FM_MIN_POOL_SIZE and
393  * UBI_FM_MAX_POOL_SIZE */
394 #define UBI_FM_MIN_POOL_SIZE	8
395 #define UBI_FM_MAX_POOL_SIZE	256
396 
397 /**
398  * struct ubi_fm_sb - UBI fastmap super block
399  * @magic: fastmap super block magic number (%UBI_FM_SB_MAGIC)
400  * @version: format version of this fastmap
401  * @data_crc: CRC over the fastmap data
402  * @used_blocks: number of PEBs used by this fastmap
403  * @block_loc: an array containing the location of all PEBs of the fastmap
404  * @block_ec: the erase counter of each used PEB
405  * @sqnum: highest sequence number value at the time while taking the fastmap
406  *
407  */
408 struct ubi_fm_sb {
409 	__be32 magic;
410 	__u8 version;
411 	__u8 padding1[3];
412 	__be32 data_crc;
413 	__be32 used_blocks;
414 	__be32 block_loc[UBI_FM_MAX_BLOCKS];
415 	__be32 block_ec[UBI_FM_MAX_BLOCKS];
416 	__be64 sqnum;
417 	__u8 padding2[32];
418 } __packed;
419 
420 /**
421  * struct ubi_fm_hdr - header of the fastmap data set
422  * @magic: fastmap header magic number (%UBI_FM_HDR_MAGIC)
423  * @free_peb_count: number of free PEBs known by this fastmap
424  * @used_peb_count: number of used PEBs known by this fastmap
425  * @scrub_peb_count: number of to be scrubbed PEBs known by this fastmap
426  * @bad_peb_count: number of bad PEBs known by this fastmap
427  * @erase_peb_count: number of bad PEBs which have to be erased
428  * @vol_count: number of UBI volumes known by this fastmap
429  */
430 struct ubi_fm_hdr {
431 	__be32 magic;
432 	__be32 free_peb_count;
433 	__be32 used_peb_count;
434 	__be32 scrub_peb_count;
435 	__be32 bad_peb_count;
436 	__be32 erase_peb_count;
437 	__be32 vol_count;
438 	__u8 padding[4];
439 } __packed;
440 
441 /* struct ubi_fm_hdr is followed by two struct ubi_fm_scan_pool */
442 
443 /**
444  * struct ubi_fm_scan_pool - Fastmap pool PEBs to be scanned while attaching
445  * @magic: pool magic numer (%UBI_FM_POOL_MAGIC)
446  * @size: current pool size
447  * @max_size: maximal pool size
448  * @pebs: an array containing the location of all PEBs in this pool
449  */
450 struct ubi_fm_scan_pool {
451 	__be32 magic;
452 	__be16 size;
453 	__be16 max_size;
454 	__be32 pebs[UBI_FM_MAX_POOL_SIZE];
455 	__be32 padding[4];
456 } __packed;
457 
458 /* ubi_fm_scan_pool is followed by nfree+nused struct ubi_fm_ec records */
459 
460 /**
461  * struct ubi_fm_ec - stores the erase counter of a PEB
462  * @pnum: PEB number
463  * @ec: ec of this PEB
464  */
465 struct ubi_fm_ec {
466 	__be32 pnum;
467 	__be32 ec;
468 } __packed;
469 
470 /**
471  * struct ubi_fm_volhdr - Fastmap volume header
472  * it identifies the start of an eba table
473  * @magic: Fastmap volume header magic number (%UBI_FM_VHDR_MAGIC)
474  * @vol_id: volume id of the fastmapped volume
475  * @vol_type: type of the fastmapped volume
476  * @data_pad: data_pad value of the fastmapped volume
477  * @used_ebs: number of used LEBs within this volume
478  * @last_eb_bytes: number of bytes used in the last LEB
479  */
480 struct ubi_fm_volhdr {
481 	__be32 magic;
482 	__be32 vol_id;
483 	__u8 vol_type;
484 	__u8 padding1[3];
485 	__be32 data_pad;
486 	__be32 used_ebs;
487 	__be32 last_eb_bytes;
488 	__u8 padding2[8];
489 } __packed;
490 
491 /* struct ubi_fm_volhdr is followed by one struct ubi_fm_eba records */
492 
493 /**
494  * struct ubi_fm_eba - denotes an association beween a PEB and LEB
495  * @magic: EBA table magic number
496  * @reserved_pebs: number of table entries
497  * @pnum: PEB number of LEB (LEB is the index)
498  */
499 struct ubi_fm_eba {
500 	__be32 magic;
501 	__be32 reserved_pebs;
502 	__be32 pnum[0];
503 } __packed;
504 #endif /* !__UBI_MEDIA_H__ */
505