xref: /linux/drivers/mtd/ubi/ubi-media.h (revision 0be3ff0c)
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[];
502 } __packed;
503 #endif /* !__UBI_MEDIA_H__ */
504