xref: /linux/drivers/mtd/ubi/ubi-media.h (revision bfd5bb6f90af092aa345b15cd78143956a13c2a8)
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  *
49  * %UBI_VTBL_AUTORESIZE_FLG flag can be set only for one volume in the volume
50  * table. UBI automatically re-sizes the volume which has this flag and makes
51  * the volume to be of largest possible size. This means that if after the
52  * initialization UBI finds out that there are available physical eraseblocks
53  * present on the device, it automatically appends all of them to the volume
54  * (the physical eraseblocks reserved for bad eraseblocks handling and other
55  * reserved physical eraseblocks are not taken). So, if there is a volume with
56  * the %UBI_VTBL_AUTORESIZE_FLG flag set, the amount of available logical
57  * eraseblocks will be zero after UBI is loaded, because all of them will be
58  * reserved for this volume. Note, the %UBI_VTBL_AUTORESIZE_FLG bit is cleared
59  * after the volume had been initialized.
60  *
61  * The auto-resize feature is useful for device production purposes. For
62  * example, different NAND flash chips may have different amount of initial bad
63  * eraseblocks, depending of particular chip instance. Manufacturers of NAND
64  * chips usually guarantee that the amount of initial bad eraseblocks does not
65  * exceed certain percent, e.g. 2%. When one creates an UBI image which will be
66  * flashed to the end devices in production, he does not know the exact amount
67  * of good physical eraseblocks the NAND chip on the device will have, but this
68  * number is required to calculate the volume sized and put them to the volume
69  * table of the UBI image. In this case, one of the volumes (e.g., the one
70  * which will store the root file system) is marked as "auto-resizable", and
71  * UBI will adjust its size on the first boot if needed.
72  *
73  * Note, first UBI reserves some amount of physical eraseblocks for bad
74  * eraseblock handling, and then re-sizes the volume, not vice-versa. This
75  * means that the pool of reserved physical eraseblocks will always be present.
76  */
77 enum {
78 	UBI_VTBL_AUTORESIZE_FLG = 0x01,
79 };
80 
81 /*
82  * Compatibility constants used by internal volumes.
83  *
84  * @UBI_COMPAT_DELETE: delete this internal volume before anything is written
85  *                     to the flash
86  * @UBI_COMPAT_RO: attach this device in read-only mode
87  * @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its
88  *                       physical eraseblocks, don't allow the wear-leveling
89  *                       sub-system to move them
90  * @UBI_COMPAT_REJECT: reject this UBI image
91  */
92 enum {
93 	UBI_COMPAT_DELETE   = 1,
94 	UBI_COMPAT_RO       = 2,
95 	UBI_COMPAT_PRESERVE = 4,
96 	UBI_COMPAT_REJECT   = 5
97 };
98 
99 /* Sizes of UBI headers */
100 #define UBI_EC_HDR_SIZE  sizeof(struct ubi_ec_hdr)
101 #define UBI_VID_HDR_SIZE sizeof(struct ubi_vid_hdr)
102 
103 /* Sizes of UBI headers without the ending CRC */
104 #define UBI_EC_HDR_SIZE_CRC  (UBI_EC_HDR_SIZE  - sizeof(__be32))
105 #define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(__be32))
106 
107 /**
108  * struct ubi_ec_hdr - UBI erase counter header.
109  * @magic: erase counter header magic number (%UBI_EC_HDR_MAGIC)
110  * @version: version of UBI implementation which is supposed to accept this
111  *           UBI image
112  * @padding1: reserved for future, zeroes
113  * @ec: the erase counter
114  * @vid_hdr_offset: where the VID header starts
115  * @data_offset: where the user data start
116  * @image_seq: image sequence number
117  * @padding2: reserved for future, zeroes
118  * @hdr_crc: erase counter header CRC checksum
119  *
120  * The erase counter header takes 64 bytes and has a plenty of unused space for
121  * future usage. The unused fields are zeroed. The @version field is used to
122  * indicate the version of UBI implementation which is supposed to be able to
123  * work with this UBI image. If @version is greater than the current UBI
124  * version, the image is rejected. This may be useful in future if something
125  * is changed radically. This field is duplicated in the volume identifier
126  * header.
127  *
128  * The @vid_hdr_offset and @data_offset fields contain the offset of the the
129  * volume identifier header and user data, relative to the beginning of the
130  * physical eraseblock. These values have to be the same for all physical
131  * eraseblocks.
132  *
133  * The @image_seq field is used to validate a UBI image that has been prepared
134  * for a UBI device. The @image_seq value can be any value, but it must be the
135  * same on all eraseblocks. UBI will ensure that all new erase counter headers
136  * also contain this value, and will check the value when attaching the flash.
137  * One way to make use of @image_seq is to increase its value by one every time
138  * an image is flashed over an existing image, then, if the flashing does not
139  * complete, UBI will detect the error when attaching the media.
140  */
141 struct ubi_ec_hdr {
142 	__be32  magic;
143 	__u8    version;
144 	__u8    padding1[3];
145 	__be64  ec; /* Warning: the current limit is 31-bit anyway! */
146 	__be32  vid_hdr_offset;
147 	__be32  data_offset;
148 	__be32  image_seq;
149 	__u8    padding2[32];
150 	__be32  hdr_crc;
151 } __packed;
152 
153 /**
154  * struct ubi_vid_hdr - on-flash UBI volume identifier header.
155  * @magic: volume identifier header magic number (%UBI_VID_HDR_MAGIC)
156  * @version: UBI implementation version which is supposed to accept this UBI
157  *           image (%UBI_VERSION)
158  * @vol_type: volume type (%UBI_VID_DYNAMIC or %UBI_VID_STATIC)
159  * @copy_flag: if this logical eraseblock was copied from another physical
160  *             eraseblock (for wear-leveling reasons)
161  * @compat: compatibility of this volume (%0, %UBI_COMPAT_DELETE,
162  *          %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT)
163  * @vol_id: ID of this volume
164  * @lnum: logical eraseblock number
165  * @padding1: reserved for future, zeroes
166  * @data_size: how many bytes of data this logical eraseblock contains
167  * @used_ebs: total number of used logical eraseblocks in this volume
168  * @data_pad: how many bytes at the end of this physical eraseblock are not
169  *            used
170  * @data_crc: CRC checksum of the data stored in this logical eraseblock
171  * @padding2: reserved for future, zeroes
172  * @sqnum: sequence number
173  * @padding3: reserved for future, zeroes
174  * @hdr_crc: volume identifier header CRC checksum
175  *
176  * The @sqnum is the value of the global sequence counter at the time when this
177  * VID header was created. The global sequence counter is incremented each time
178  * UBI writes a new VID header to the flash, i.e. when it maps a logical
179  * eraseblock to a new physical eraseblock. The global sequence counter is an
180  * unsigned 64-bit integer and we assume it never overflows. The @sqnum
181  * (sequence number) is used to distinguish between older and newer versions of
182  * logical eraseblocks.
183  *
184  * There are 2 situations when there may be more than one physical eraseblock
185  * corresponding to the same logical eraseblock, i.e., having the same @vol_id
186  * and @lnum values in the volume identifier header. Suppose we have a logical
187  * eraseblock L and it is mapped to the physical eraseblock P.
188  *
189  * 1. Because UBI may erase physical eraseblocks asynchronously, the following
190  * situation is possible: L is asynchronously erased, so P is scheduled for
191  * erasure, then L is written to,i.e. mapped to another physical eraseblock P1,
192  * so P1 is written to, then an unclean reboot happens. Result - there are 2
193  * physical eraseblocks P and P1 corresponding to the same logical eraseblock
194  * L. But P1 has greater sequence number, so UBI picks P1 when it attaches the
195  * flash.
196  *
197  * 2. From time to time UBI moves logical eraseblocks to other physical
198  * eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P
199  * to P1, and an unclean reboot happens before P is physically erased, there
200  * are two physical eraseblocks P and P1 corresponding to L and UBI has to
201  * select one of them when the flash is attached. The @sqnum field says which
202  * PEB is the original (obviously P will have lower @sqnum) and the copy. But
203  * it is not enough to select the physical eraseblock with the higher sequence
204  * number, because the unclean reboot could have happen in the middle of the
205  * copying process, so the data in P is corrupted. It is also not enough to
206  * just select the physical eraseblock with lower sequence number, because the
207  * data there may be old (consider a case if more data was added to P1 after
208  * the copying). Moreover, the unclean reboot may happen when the erasure of P
209  * was just started, so it result in unstable P, which is "mostly" OK, but
210  * still has unstable bits.
211  *
212  * UBI uses the @copy_flag field to indicate that this logical eraseblock is a
213  * copy. UBI also calculates data CRC when the data is moved and stores it at
214  * the @data_crc field of the copy (P1). So when UBI needs to pick one physical
215  * eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is
216  * examined. If it is cleared, the situation is simple and the newer one is
217  * picked. If it is set, the data CRC of the copy (P1) is examined. If the CRC
218  * checksum is correct, this physical eraseblock is selected (P1). Otherwise
219  * the older one (P) is selected.
220  *
221  * There are 2 sorts of volumes in UBI: user volumes and internal volumes.
222  * Internal volumes are not seen from outside and are used for various internal
223  * UBI purposes. In this implementation there is only one internal volume - the
224  * layout volume. Internal volumes are the main mechanism of UBI extensions.
225  * For example, in future one may introduce a journal internal volume. Internal
226  * volumes have their own reserved range of IDs.
227  *
228  * The @compat field is only used for internal volumes and contains the "degree
229  * of their compatibility". It is always zero for user volumes. This field
230  * provides a mechanism to introduce UBI extensions and to be still compatible
231  * with older UBI binaries. For example, if someone introduced a journal in
232  * future, he would probably use %UBI_COMPAT_DELETE compatibility for the
233  * journal volume.  And in this case, older UBI binaries, which know nothing
234  * about the journal volume, would just delete this volume and work perfectly
235  * fine. This is similar to what Ext2fs does when it is fed by an Ext3fs image
236  * - it just ignores the Ext3fs journal.
237  *
238  * The @data_crc field contains the CRC checksum of the contents of the logical
239  * eraseblock if this is a static volume. In case of dynamic volumes, it does
240  * not contain the CRC checksum as a rule. The only exception is when the
241  * data of the physical eraseblock was moved by the wear-leveling sub-system,
242  * then the wear-leveling sub-system calculates the data CRC and stores it in
243  * the @data_crc field. And of course, the @copy_flag is %in this case.
244  *
245  * The @data_size field is used only for static volumes because UBI has to know
246  * how many bytes of data are stored in this eraseblock. For dynamic volumes,
247  * this field usually contains zero. The only exception is when the data of the
248  * physical eraseblock was moved to another physical eraseblock for
249  * wear-leveling reasons. In this case, UBI calculates CRC checksum of the
250  * contents and uses both @data_crc and @data_size fields. In this case, the
251  * @data_size field contains data size.
252  *
253  * The @used_ebs field is used only for static volumes and indicates how many
254  * eraseblocks the data of the volume takes. For dynamic volumes this field is
255  * not used and always contains zero.
256  *
257  * The @data_pad is calculated when volumes are created using the alignment
258  * parameter. So, effectively, the @data_pad field reduces the size of logical
259  * eraseblocks of this volume. This is very handy when one uses block-oriented
260  * software (say, cramfs) on top of the UBI volume.
261  */
262 struct ubi_vid_hdr {
263 	__be32  magic;
264 	__u8    version;
265 	__u8    vol_type;
266 	__u8    copy_flag;
267 	__u8    compat;
268 	__be32  vol_id;
269 	__be32  lnum;
270 	__u8    padding1[4];
271 	__be32  data_size;
272 	__be32  used_ebs;
273 	__be32  data_pad;
274 	__be32  data_crc;
275 	__u8    padding2[4];
276 	__be64  sqnum;
277 	__u8    padding3[12];
278 	__be32  hdr_crc;
279 } __packed;
280 
281 /* Internal UBI volumes count */
282 #define UBI_INT_VOL_COUNT 1
283 
284 /*
285  * Starting ID of internal volumes: 0x7fffefff.
286  * There is reserved room for 4096 internal volumes.
287  */
288 #define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096)
289 
290 /* The layout volume contains the volume table */
291 
292 #define UBI_LAYOUT_VOLUME_ID     UBI_INTERNAL_VOL_START
293 #define UBI_LAYOUT_VOLUME_TYPE   UBI_VID_DYNAMIC
294 #define UBI_LAYOUT_VOLUME_ALIGN  1
295 #define UBI_LAYOUT_VOLUME_EBS    2
296 #define UBI_LAYOUT_VOLUME_NAME   "layout volume"
297 #define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT
298 
299 /* The maximum number of volumes per one UBI device */
300 #define UBI_MAX_VOLUMES 128
301 
302 /* The maximum volume name length */
303 #define UBI_VOL_NAME_MAX 127
304 
305 /* Size of the volume table record */
306 #define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vtbl_record)
307 
308 /* Size of the volume table record without the ending CRC */
309 #define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(__be32))
310 
311 /**
312  * struct ubi_vtbl_record - a record in the volume table.
313  * @reserved_pebs: how many physical eraseblocks are reserved for this volume
314  * @alignment: volume alignment
315  * @data_pad: how many bytes are unused at the end of the each physical
316  * eraseblock to satisfy the requested alignment
317  * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
318  * @upd_marker: if volume update was started but not finished
319  * @name_len: volume name length
320  * @name: the volume name
321  * @flags: volume flags (%UBI_VTBL_AUTORESIZE_FLG)
322  * @padding: reserved, zeroes
323  * @crc: a CRC32 checksum of the record
324  *
325  * The volume table records are stored in the volume table, which is stored in
326  * the layout volume. The layout volume consists of 2 logical eraseblock, each
327  * of which contains a copy of the volume table (i.e., the volume table is
328  * duplicated). The volume table is an array of &struct ubi_vtbl_record
329  * objects indexed by the volume ID.
330  *
331  * If the size of the logical eraseblock is large enough to fit
332  * %UBI_MAX_VOLUMES records, the volume table contains %UBI_MAX_VOLUMES
333  * records. Otherwise, it contains as many records as it can fit (i.e., size of
334  * logical eraseblock divided by sizeof(struct ubi_vtbl_record)).
335  *
336  * The @upd_marker flag is used to implement volume update. It is set to %1
337  * before update and set to %0 after the update. So if the update operation was
338  * interrupted, UBI knows that the volume is corrupted.
339  *
340  * The @alignment field is specified when the volume is created and cannot be
341  * later changed. It may be useful, for example, when a block-oriented file
342  * system works on top of UBI. The @data_pad field is calculated using the
343  * logical eraseblock size and @alignment. The alignment must be multiple to the
344  * minimal flash I/O unit. If @alignment is 1, all the available space of
345  * the physical eraseblocks is used.
346  *
347  * Empty records contain all zeroes and the CRC checksum of those zeroes.
348  */
349 struct ubi_vtbl_record {
350 	__be32  reserved_pebs;
351 	__be32  alignment;
352 	__be32  data_pad;
353 	__u8    vol_type;
354 	__u8    upd_marker;
355 	__be16  name_len;
356 	__u8    name[UBI_VOL_NAME_MAX+1];
357 	__u8    flags;
358 	__u8    padding[23];
359 	__be32  crc;
360 } __packed;
361 
362 /* UBI fastmap on-flash data structures */
363 
364 #define UBI_FM_SB_VOLUME_ID	(UBI_LAYOUT_VOLUME_ID + 1)
365 #define UBI_FM_DATA_VOLUME_ID	(UBI_LAYOUT_VOLUME_ID + 2)
366 
367 /* fastmap on-flash data structure format version */
368 #define UBI_FM_FMT_VERSION	1
369 
370 #define UBI_FM_SB_MAGIC		0x7B11D69F
371 #define UBI_FM_HDR_MAGIC	0xD4B82EF7
372 #define UBI_FM_VHDR_MAGIC	0xFA370ED1
373 #define UBI_FM_POOL_MAGIC	0x67AF4D08
374 #define UBI_FM_EBA_MAGIC	0xf0c040a8
375 
376 /* A fastmap super block can be located between PEB 0 and
377  * UBI_FM_MAX_START */
378 #define UBI_FM_MAX_START	64
379 
380 /* A fastmap can use up to UBI_FM_MAX_BLOCKS PEBs */
381 #define UBI_FM_MAX_BLOCKS	32
382 
383 /* 5% of the total number of PEBs have to be scanned while attaching
384  * from a fastmap.
385  * But the size of this pool is limited to be between UBI_FM_MIN_POOL_SIZE and
386  * UBI_FM_MAX_POOL_SIZE */
387 #define UBI_FM_MIN_POOL_SIZE	8
388 #define UBI_FM_MAX_POOL_SIZE	256
389 
390 /**
391  * struct ubi_fm_sb - UBI fastmap super block
392  * @magic: fastmap super block magic number (%UBI_FM_SB_MAGIC)
393  * @version: format version of this fastmap
394  * @data_crc: CRC over the fastmap data
395  * @used_blocks: number of PEBs used by this fastmap
396  * @block_loc: an array containing the location of all PEBs of the fastmap
397  * @block_ec: the erase counter of each used PEB
398  * @sqnum: highest sequence number value at the time while taking the fastmap
399  *
400  */
401 struct ubi_fm_sb {
402 	__be32 magic;
403 	__u8 version;
404 	__u8 padding1[3];
405 	__be32 data_crc;
406 	__be32 used_blocks;
407 	__be32 block_loc[UBI_FM_MAX_BLOCKS];
408 	__be32 block_ec[UBI_FM_MAX_BLOCKS];
409 	__be64 sqnum;
410 	__u8 padding2[32];
411 } __packed;
412 
413 /**
414  * struct ubi_fm_hdr - header of the fastmap data set
415  * @magic: fastmap header magic number (%UBI_FM_HDR_MAGIC)
416  * @free_peb_count: number of free PEBs known by this fastmap
417  * @used_peb_count: number of used PEBs known by this fastmap
418  * @scrub_peb_count: number of to be scrubbed PEBs known by this fastmap
419  * @bad_peb_count: number of bad PEBs known by this fastmap
420  * @erase_peb_count: number of bad PEBs which have to be erased
421  * @vol_count: number of UBI volumes known by this fastmap
422  */
423 struct ubi_fm_hdr {
424 	__be32 magic;
425 	__be32 free_peb_count;
426 	__be32 used_peb_count;
427 	__be32 scrub_peb_count;
428 	__be32 bad_peb_count;
429 	__be32 erase_peb_count;
430 	__be32 vol_count;
431 	__u8 padding[4];
432 } __packed;
433 
434 /* struct ubi_fm_hdr is followed by two struct ubi_fm_scan_pool */
435 
436 /**
437  * struct ubi_fm_scan_pool - Fastmap pool PEBs to be scanned while attaching
438  * @magic: pool magic numer (%UBI_FM_POOL_MAGIC)
439  * @size: current pool size
440  * @max_size: maximal pool size
441  * @pebs: an array containing the location of all PEBs in this pool
442  */
443 struct ubi_fm_scan_pool {
444 	__be32 magic;
445 	__be16 size;
446 	__be16 max_size;
447 	__be32 pebs[UBI_FM_MAX_POOL_SIZE];
448 	__be32 padding[4];
449 } __packed;
450 
451 /* ubi_fm_scan_pool is followed by nfree+nused struct ubi_fm_ec records */
452 
453 /**
454  * struct ubi_fm_ec - stores the erase counter of a PEB
455  * @pnum: PEB number
456  * @ec: ec of this PEB
457  */
458 struct ubi_fm_ec {
459 	__be32 pnum;
460 	__be32 ec;
461 } __packed;
462 
463 /**
464  * struct ubi_fm_volhdr - Fastmap volume header
465  * it identifies the start of an eba table
466  * @magic: Fastmap volume header magic number (%UBI_FM_VHDR_MAGIC)
467  * @vol_id: volume id of the fastmapped volume
468  * @vol_type: type of the fastmapped volume
469  * @data_pad: data_pad value of the fastmapped volume
470  * @used_ebs: number of used LEBs within this volume
471  * @last_eb_bytes: number of bytes used in the last LEB
472  */
473 struct ubi_fm_volhdr {
474 	__be32 magic;
475 	__be32 vol_id;
476 	__u8 vol_type;
477 	__u8 padding1[3];
478 	__be32 data_pad;
479 	__be32 used_ebs;
480 	__be32 last_eb_bytes;
481 	__u8 padding2[8];
482 } __packed;
483 
484 /* struct ubi_fm_volhdr is followed by one struct ubi_fm_eba records */
485 
486 /**
487  * struct ubi_fm_eba - denotes an association between a PEB and LEB
488  * @magic: EBA table magic number
489  * @reserved_pebs: number of table entries
490  * @pnum: PEB number of LEB (LEB is the index)
491  */
492 struct ubi_fm_eba {
493 	__be32 magic;
494 	__be32 reserved_pebs;
495 	__be32 pnum[0];
496 } __packed;
497 #endif /* !__UBI_MEDIA_H__ */
498