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1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (c) International Business Machines Corp., 2006
4  *
5  * Author: Artem Bityutskiy (Битюцкий Артём)
6  */
7 
8 /*
9  * UBI attaching sub-system.
10  *
11  * This sub-system is responsible for attaching MTD devices and it also
12  * implements flash media scanning.
13  *
14  * The attaching information is represented by a &struct ubi_attach_info'
15  * object. Information about volumes is represented by &struct ubi_ainf_volume
16  * objects which are kept in volume RB-tree with root at the @volumes field.
17  * The RB-tree is indexed by the volume ID.
18  *
19  * Logical eraseblocks are represented by &struct ubi_ainf_peb objects. These
20  * objects are kept in per-volume RB-trees with the root at the corresponding
21  * &struct ubi_ainf_volume object. To put it differently, we keep an RB-tree of
22  * per-volume objects and each of these objects is the root of RB-tree of
23  * per-LEB objects.
24  *
25  * Corrupted physical eraseblocks are put to the @corr list, free physical
26  * eraseblocks are put to the @free list and the physical eraseblock to be
27  * erased are put to the @erase list.
28  *
29  * About corruptions
30  * ~~~~~~~~~~~~~~~~~
31  *
32  * UBI protects EC and VID headers with CRC-32 checksums, so it can detect
33  * whether the headers are corrupted or not. Sometimes UBI also protects the
34  * data with CRC-32, e.g., when it executes the atomic LEB change operation, or
35  * when it moves the contents of a PEB for wear-leveling purposes.
36  *
37  * UBI tries to distinguish between 2 types of corruptions.
38  *
39  * 1. Corruptions caused by power cuts. These are expected corruptions and UBI
40  * tries to handle them gracefully, without printing too many warnings and
41  * error messages. The idea is that we do not lose important data in these
42  * cases - we may lose only the data which were being written to the media just
43  * before the power cut happened, and the upper layers (e.g., UBIFS) are
44  * supposed to handle such data losses (e.g., by using the FS journal).
45  *
46  * When UBI detects a corruption (CRC-32 mismatch) in a PEB, and it looks like
47  * the reason is a power cut, UBI puts this PEB to the @erase list, and all
48  * PEBs in the @erase list are scheduled for erasure later.
49  *
50  * 2. Unexpected corruptions which are not caused by power cuts. During
51  * attaching, such PEBs are put to the @corr list and UBI preserves them.
52  * Obviously, this lessens the amount of available PEBs, and if at some  point
53  * UBI runs out of free PEBs, it switches to R/O mode. UBI also loudly informs
54  * about such PEBs every time the MTD device is attached.
55  *
56  * However, it is difficult to reliably distinguish between these types of
57  * corruptions and UBI's strategy is as follows (in case of attaching by
58  * scanning). UBI assumes corruption type 2 if the VID header is corrupted and
59  * the data area does not contain all 0xFFs, and there were no bit-flips or
60  * integrity errors (e.g., ECC errors in case of NAND) while reading the data
61  * area.  Otherwise UBI assumes corruption type 1. So the decision criteria
62  * are as follows.
63  *   o If the data area contains only 0xFFs, there are no data, and it is safe
64  *     to just erase this PEB - this is corruption type 1.
65  *   o If the data area has bit-flips or data integrity errors (ECC errors on
66  *     NAND), it is probably a PEB which was being erased when power cut
67  *     happened, so this is corruption type 1. However, this is just a guess,
68  *     which might be wrong.
69  *   o Otherwise this is corruption type 2.
70  */
71 
72 #ifndef __UBOOT__
73 #include <linux/err.h>
74 #include <linux/slab.h>
75 #include <linux/crc32.h>
76 #include <linux/random.h>
77 #else
78 #include <div64.h>
79 #include <linux/err.h>
80 #endif
81 
82 #include <linux/math64.h>
83 
84 #include <ubi_uboot.h>
85 #include "ubi.h"
86 
87 static int self_check_ai(struct ubi_device *ubi, struct ubi_attach_info *ai);
88 
89 /* Temporary variables used during scanning */
90 static struct ubi_ec_hdr *ech;
91 static struct ubi_vid_hdr *vidh;
92 
93 /**
94  * add_to_list - add physical eraseblock to a list.
95  * @ai: attaching information
96  * @pnum: physical eraseblock number to add
97  * @vol_id: the last used volume id for the PEB
98  * @lnum: the last used LEB number for the PEB
99  * @ec: erase counter of the physical eraseblock
100  * @to_head: if not zero, add to the head of the list
101  * @list: the list to add to
102  *
103  * This function allocates a 'struct ubi_ainf_peb' object for physical
104  * eraseblock @pnum and adds it to the "free", "erase", or "alien" lists.
105  * It stores the @lnum and @vol_id alongside, which can both be
106  * %UBI_UNKNOWN if they are not available, not readable, or not assigned.
107  * If @to_head is not zero, PEB will be added to the head of the list, which
108  * basically means it will be processed first later. E.g., we add corrupted
109  * PEBs (corrupted due to power cuts) to the head of the erase list to make
110  * sure we erase them first and get rid of corruptions ASAP. This function
111  * returns zero in case of success and a negative error code in case of
112  * failure.
113  */
add_to_list(struct ubi_attach_info * ai,int pnum,int vol_id,int lnum,int ec,int to_head,struct list_head * list)114 static int add_to_list(struct ubi_attach_info *ai, int pnum, int vol_id,
115 		       int lnum, int ec, int to_head, struct list_head *list)
116 {
117 	struct ubi_ainf_peb *aeb;
118 
119 	if (list == &ai->free) {
120 		dbg_bld("add to free: PEB %d, EC %d", pnum, ec);
121 	} else if (list == &ai->erase) {
122 		dbg_bld("add to erase: PEB %d, EC %d", pnum, ec);
123 	} else if (list == &ai->alien) {
124 		dbg_bld("add to alien: PEB %d, EC %d", pnum, ec);
125 		ai->alien_peb_count += 1;
126 	} else
127 		BUG();
128 
129 	aeb = kmem_cache_alloc(ai->aeb_slab_cache, GFP_KERNEL);
130 	if (!aeb)
131 		return -ENOMEM;
132 
133 	aeb->pnum = pnum;
134 	aeb->vol_id = vol_id;
135 	aeb->lnum = lnum;
136 	aeb->ec = ec;
137 	if (to_head)
138 		list_add(&aeb->u.list, list);
139 	else
140 		list_add_tail(&aeb->u.list, list);
141 	return 0;
142 }
143 
144 /**
145  * add_corrupted - add a corrupted physical eraseblock.
146  * @ai: attaching information
147  * @pnum: physical eraseblock number to add
148  * @ec: erase counter of the physical eraseblock
149  *
150  * This function allocates a 'struct ubi_ainf_peb' object for a corrupted
151  * physical eraseblock @pnum and adds it to the 'corr' list.  The corruption
152  * was presumably not caused by a power cut. Returns zero in case of success
153  * and a negative error code in case of failure.
154  */
add_corrupted(struct ubi_attach_info * ai,int pnum,int ec)155 static int add_corrupted(struct ubi_attach_info *ai, int pnum, int ec)
156 {
157 	struct ubi_ainf_peb *aeb;
158 
159 	dbg_bld("add to corrupted: PEB %d, EC %d", pnum, ec);
160 
161 	aeb = kmem_cache_alloc(ai->aeb_slab_cache, GFP_KERNEL);
162 	if (!aeb)
163 		return -ENOMEM;
164 
165 	ai->corr_peb_count += 1;
166 	aeb->pnum = pnum;
167 	aeb->ec = ec;
168 	list_add(&aeb->u.list, &ai->corr);
169 	return 0;
170 }
171 
172 /**
173  * validate_vid_hdr - check volume identifier header.
174  * @ubi: UBI device description object
175  * @vid_hdr: the volume identifier header to check
176  * @av: information about the volume this logical eraseblock belongs to
177  * @pnum: physical eraseblock number the VID header came from
178  *
179  * This function checks that data stored in @vid_hdr is consistent. Returns
180  * non-zero if an inconsistency was found and zero if not.
181  *
182  * Note, UBI does sanity check of everything it reads from the flash media.
183  * Most of the checks are done in the I/O sub-system. Here we check that the
184  * information in the VID header is consistent to the information in other VID
185  * headers of the same volume.
186  */
validate_vid_hdr(const struct ubi_device * ubi,const struct ubi_vid_hdr * vid_hdr,const struct ubi_ainf_volume * av,int pnum)187 static int validate_vid_hdr(const struct ubi_device *ubi,
188 			    const struct ubi_vid_hdr *vid_hdr,
189 			    const struct ubi_ainf_volume *av, int pnum)
190 {
191 	int vol_type = vid_hdr->vol_type;
192 	int vol_id = be32_to_cpu(vid_hdr->vol_id);
193 	int used_ebs = be32_to_cpu(vid_hdr->used_ebs);
194 	int data_pad = be32_to_cpu(vid_hdr->data_pad);
195 
196 	if (av->leb_count != 0) {
197 		int av_vol_type;
198 
199 		/*
200 		 * This is not the first logical eraseblock belonging to this
201 		 * volume. Ensure that the data in its VID header is consistent
202 		 * to the data in previous logical eraseblock headers.
203 		 */
204 
205 		if (vol_id != av->vol_id) {
206 			ubi_err(ubi, "inconsistent vol_id");
207 			goto bad;
208 		}
209 
210 		if (av->vol_type == UBI_STATIC_VOLUME)
211 			av_vol_type = UBI_VID_STATIC;
212 		else
213 			av_vol_type = UBI_VID_DYNAMIC;
214 
215 		if (vol_type != av_vol_type) {
216 			ubi_err(ubi, "inconsistent vol_type");
217 			goto bad;
218 		}
219 
220 		if (used_ebs != av->used_ebs) {
221 			ubi_err(ubi, "inconsistent used_ebs");
222 			goto bad;
223 		}
224 
225 		if (data_pad != av->data_pad) {
226 			ubi_err(ubi, "inconsistent data_pad");
227 			goto bad;
228 		}
229 	}
230 
231 	return 0;
232 
233 bad:
234 	ubi_err(ubi, "inconsistent VID header at PEB %d", pnum);
235 	ubi_dump_vid_hdr(vid_hdr);
236 	ubi_dump_av(av);
237 	return -EINVAL;
238 }
239 
240 /**
241  * add_volume - add volume to the attaching information.
242  * @ai: attaching information
243  * @vol_id: ID of the volume to add
244  * @pnum: physical eraseblock number
245  * @vid_hdr: volume identifier header
246  *
247  * If the volume corresponding to the @vid_hdr logical eraseblock is already
248  * present in the attaching information, this function does nothing. Otherwise
249  * it adds corresponding volume to the attaching information. Returns a pointer
250  * to the allocated "av" object in case of success and a negative error code in
251  * case of failure.
252  */
add_volume(struct ubi_attach_info * ai,int vol_id,int pnum,const struct ubi_vid_hdr * vid_hdr)253 static struct ubi_ainf_volume *add_volume(struct ubi_attach_info *ai,
254 					  int vol_id, int pnum,
255 					  const struct ubi_vid_hdr *vid_hdr)
256 {
257 	struct ubi_ainf_volume *av;
258 	struct rb_node **p = &ai->volumes.rb_node, *parent = NULL;
259 
260 	ubi_assert(vol_id == be32_to_cpu(vid_hdr->vol_id));
261 
262 	/* Walk the volume RB-tree to look if this volume is already present */
263 	while (*p) {
264 		parent = *p;
265 		av = rb_entry(parent, struct ubi_ainf_volume, rb);
266 
267 		if (vol_id == av->vol_id)
268 			return av;
269 
270 		if (vol_id > av->vol_id)
271 			p = &(*p)->rb_left;
272 		else
273 			p = &(*p)->rb_right;
274 	}
275 
276 	/* The volume is absent - add it */
277 	av = kmalloc(sizeof(struct ubi_ainf_volume), GFP_KERNEL);
278 	if (!av)
279 		return ERR_PTR(-ENOMEM);
280 
281 	av->highest_lnum = av->leb_count = 0;
282 	av->vol_id = vol_id;
283 	av->root = RB_ROOT;
284 	av->used_ebs = be32_to_cpu(vid_hdr->used_ebs);
285 	av->data_pad = be32_to_cpu(vid_hdr->data_pad);
286 	av->compat = vid_hdr->compat;
287 	av->vol_type = vid_hdr->vol_type == UBI_VID_DYNAMIC ? UBI_DYNAMIC_VOLUME
288 							    : UBI_STATIC_VOLUME;
289 	if (vol_id > ai->highest_vol_id)
290 		ai->highest_vol_id = vol_id;
291 
292 	rb_link_node(&av->rb, parent, p);
293 	rb_insert_color(&av->rb, &ai->volumes);
294 	ai->vols_found += 1;
295 	dbg_bld("added volume %d", vol_id);
296 	return av;
297 }
298 
299 /**
300  * ubi_compare_lebs - find out which logical eraseblock is newer.
301  * @ubi: UBI device description object
302  * @aeb: first logical eraseblock to compare
303  * @pnum: physical eraseblock number of the second logical eraseblock to
304  * compare
305  * @vid_hdr: volume identifier header of the second logical eraseblock
306  *
307  * This function compares 2 copies of a LEB and informs which one is newer. In
308  * case of success this function returns a positive value, in case of failure, a
309  * negative error code is returned. The success return codes use the following
310  * bits:
311  *     o bit 0 is cleared: the first PEB (described by @aeb) is newer than the
312  *       second PEB (described by @pnum and @vid_hdr);
313  *     o bit 0 is set: the second PEB is newer;
314  *     o bit 1 is cleared: no bit-flips were detected in the newer LEB;
315  *     o bit 1 is set: bit-flips were detected in the newer LEB;
316  *     o bit 2 is cleared: the older LEB is not corrupted;
317  *     o bit 2 is set: the older LEB is corrupted.
318  */
ubi_compare_lebs(struct ubi_device * ubi,const struct ubi_ainf_peb * aeb,int pnum,const struct ubi_vid_hdr * vid_hdr)319 int ubi_compare_lebs(struct ubi_device *ubi, const struct ubi_ainf_peb *aeb,
320 			int pnum, const struct ubi_vid_hdr *vid_hdr)
321 {
322 	int len, err, second_is_newer, bitflips = 0, corrupted = 0;
323 	uint32_t data_crc, crc;
324 	struct ubi_vid_hdr *vh = NULL;
325 	unsigned long long sqnum2 = be64_to_cpu(vid_hdr->sqnum);
326 
327 	if (sqnum2 == aeb->sqnum) {
328 		/*
329 		 * This must be a really ancient UBI image which has been
330 		 * created before sequence numbers support has been added. At
331 		 * that times we used 32-bit LEB versions stored in logical
332 		 * eraseblocks. That was before UBI got into mainline. We do not
333 		 * support these images anymore. Well, those images still work,
334 		 * but only if no unclean reboots happened.
335 		 */
336 		ubi_err(ubi, "unsupported on-flash UBI format");
337 		return -EINVAL;
338 	}
339 
340 	/* Obviously the LEB with lower sequence counter is older */
341 	second_is_newer = (sqnum2 > aeb->sqnum);
342 
343 	/*
344 	 * Now we know which copy is newer. If the copy flag of the PEB with
345 	 * newer version is not set, then we just return, otherwise we have to
346 	 * check data CRC. For the second PEB we already have the VID header,
347 	 * for the first one - we'll need to re-read it from flash.
348 	 *
349 	 * Note: this may be optimized so that we wouldn't read twice.
350 	 */
351 
352 	if (second_is_newer) {
353 		if (!vid_hdr->copy_flag) {
354 			/* It is not a copy, so it is newer */
355 			dbg_bld("second PEB %d is newer, copy_flag is unset",
356 				pnum);
357 			return 1;
358 		}
359 	} else {
360 		if (!aeb->copy_flag) {
361 			/* It is not a copy, so it is newer */
362 			dbg_bld("first PEB %d is newer, copy_flag is unset",
363 				pnum);
364 			return bitflips << 1;
365 		}
366 
367 		vh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
368 		if (!vh)
369 			return -ENOMEM;
370 
371 		pnum = aeb->pnum;
372 		err = ubi_io_read_vid_hdr(ubi, pnum, vh, 0);
373 		if (err) {
374 			if (err == UBI_IO_BITFLIPS)
375 				bitflips = 1;
376 			else {
377 				ubi_err(ubi, "VID of PEB %d header is bad, but it was OK earlier, err %d",
378 					pnum, err);
379 				if (err > 0)
380 					err = -EIO;
381 
382 				goto out_free_vidh;
383 			}
384 		}
385 
386 		vid_hdr = vh;
387 	}
388 
389 	/* Read the data of the copy and check the CRC */
390 
391 	len = be32_to_cpu(vid_hdr->data_size);
392 
393 	mutex_lock(&ubi->buf_mutex);
394 	err = ubi_io_read_data(ubi, ubi->peb_buf, pnum, 0, len);
395 	if (err && err != UBI_IO_BITFLIPS && !mtd_is_eccerr(err))
396 		goto out_unlock;
397 
398 	data_crc = be32_to_cpu(vid_hdr->data_crc);
399 	crc = crc32(UBI_CRC32_INIT, ubi->peb_buf, len);
400 	if (crc != data_crc) {
401 		dbg_bld("PEB %d CRC error: calculated %#08x, must be %#08x",
402 			pnum, crc, data_crc);
403 		corrupted = 1;
404 		bitflips = 0;
405 		second_is_newer = !second_is_newer;
406 	} else {
407 		dbg_bld("PEB %d CRC is OK", pnum);
408 		bitflips |= !!err;
409 	}
410 	mutex_unlock(&ubi->buf_mutex);
411 
412 	ubi_free_vid_hdr(ubi, vh);
413 
414 	if (second_is_newer)
415 		dbg_bld("second PEB %d is newer, copy_flag is set", pnum);
416 	else
417 		dbg_bld("first PEB %d is newer, copy_flag is set", pnum);
418 
419 	return second_is_newer | (bitflips << 1) | (corrupted << 2);
420 
421 out_unlock:
422 	mutex_unlock(&ubi->buf_mutex);
423 out_free_vidh:
424 	ubi_free_vid_hdr(ubi, vh);
425 	return err;
426 }
427 
428 /**
429  * ubi_add_to_av - add used physical eraseblock to the attaching information.
430  * @ubi: UBI device description object
431  * @ai: attaching information
432  * @pnum: the physical eraseblock number
433  * @ec: erase counter
434  * @vid_hdr: the volume identifier header
435  * @bitflips: if bit-flips were detected when this physical eraseblock was read
436  *
437  * This function adds information about a used physical eraseblock to the
438  * 'used' tree of the corresponding volume. The function is rather complex
439  * because it has to handle cases when this is not the first physical
440  * eraseblock belonging to the same logical eraseblock, and the newer one has
441  * to be picked, while the older one has to be dropped. This function returns
442  * zero in case of success and a negative error code in case of failure.
443  */
ubi_add_to_av(struct ubi_device * ubi,struct ubi_attach_info * ai,int pnum,int ec,const struct ubi_vid_hdr * vid_hdr,int bitflips)444 int ubi_add_to_av(struct ubi_device *ubi, struct ubi_attach_info *ai, int pnum,
445 		  int ec, const struct ubi_vid_hdr *vid_hdr, int bitflips)
446 {
447 	int err, vol_id, lnum;
448 	unsigned long long sqnum;
449 	struct ubi_ainf_volume *av;
450 	struct ubi_ainf_peb *aeb;
451 	struct rb_node **p, *parent = NULL;
452 
453 	vol_id = be32_to_cpu(vid_hdr->vol_id);
454 	lnum = be32_to_cpu(vid_hdr->lnum);
455 	sqnum = be64_to_cpu(vid_hdr->sqnum);
456 
457 	dbg_bld("PEB %d, LEB %d:%d, EC %d, sqnum %llu, bitflips %d",
458 		pnum, vol_id, lnum, ec, sqnum, bitflips);
459 
460 	av = add_volume(ai, vol_id, pnum, vid_hdr);
461 	if (IS_ERR(av))
462 		return PTR_ERR(av);
463 
464 	if (ai->max_sqnum < sqnum)
465 		ai->max_sqnum = sqnum;
466 
467 	/*
468 	 * Walk the RB-tree of logical eraseblocks of volume @vol_id to look
469 	 * if this is the first instance of this logical eraseblock or not.
470 	 */
471 	p = &av->root.rb_node;
472 	while (*p) {
473 		int cmp_res;
474 
475 		parent = *p;
476 		aeb = rb_entry(parent, struct ubi_ainf_peb, u.rb);
477 		if (lnum != aeb->lnum) {
478 			if (lnum < aeb->lnum)
479 				p = &(*p)->rb_left;
480 			else
481 				p = &(*p)->rb_right;
482 			continue;
483 		}
484 
485 		/*
486 		 * There is already a physical eraseblock describing the same
487 		 * logical eraseblock present.
488 		 */
489 
490 		dbg_bld("this LEB already exists: PEB %d, sqnum %llu, EC %d",
491 			aeb->pnum, aeb->sqnum, aeb->ec);
492 
493 		/*
494 		 * Make sure that the logical eraseblocks have different
495 		 * sequence numbers. Otherwise the image is bad.
496 		 *
497 		 * However, if the sequence number is zero, we assume it must
498 		 * be an ancient UBI image from the era when UBI did not have
499 		 * sequence numbers. We still can attach these images, unless
500 		 * there is a need to distinguish between old and new
501 		 * eraseblocks, in which case we'll refuse the image in
502 		 * 'ubi_compare_lebs()'. In other words, we attach old clean
503 		 * images, but refuse attaching old images with duplicated
504 		 * logical eraseblocks because there was an unclean reboot.
505 		 */
506 		if (aeb->sqnum == sqnum && sqnum != 0) {
507 			ubi_err(ubi, "two LEBs with same sequence number %llu",
508 				sqnum);
509 			ubi_dump_aeb(aeb, 0);
510 			ubi_dump_vid_hdr(vid_hdr);
511 			return -EINVAL;
512 		}
513 
514 		/*
515 		 * Now we have to drop the older one and preserve the newer
516 		 * one.
517 		 */
518 		cmp_res = ubi_compare_lebs(ubi, aeb, pnum, vid_hdr);
519 		if (cmp_res < 0)
520 			return cmp_res;
521 
522 		if (cmp_res & 1) {
523 			/*
524 			 * This logical eraseblock is newer than the one
525 			 * found earlier.
526 			 */
527 			err = validate_vid_hdr(ubi, vid_hdr, av, pnum);
528 			if (err)
529 				return err;
530 
531 			err = add_to_list(ai, aeb->pnum, aeb->vol_id,
532 					  aeb->lnum, aeb->ec, cmp_res & 4,
533 					  &ai->erase);
534 			if (err)
535 				return err;
536 
537 			aeb->ec = ec;
538 			aeb->pnum = pnum;
539 			aeb->vol_id = vol_id;
540 			aeb->lnum = lnum;
541 			aeb->scrub = ((cmp_res & 2) || bitflips);
542 			aeb->copy_flag = vid_hdr->copy_flag;
543 			aeb->sqnum = sqnum;
544 
545 			if (av->highest_lnum == lnum)
546 				av->last_data_size =
547 					be32_to_cpu(vid_hdr->data_size);
548 
549 			return 0;
550 		} else {
551 			/*
552 			 * This logical eraseblock is older than the one found
553 			 * previously.
554 			 */
555 			return add_to_list(ai, pnum, vol_id, lnum, ec,
556 					   cmp_res & 4, &ai->erase);
557 		}
558 	}
559 
560 	/*
561 	 * We've met this logical eraseblock for the first time, add it to the
562 	 * attaching information.
563 	 */
564 
565 	err = validate_vid_hdr(ubi, vid_hdr, av, pnum);
566 	if (err)
567 		return err;
568 
569 	aeb = kmem_cache_alloc(ai->aeb_slab_cache, GFP_KERNEL);
570 	if (!aeb)
571 		return -ENOMEM;
572 
573 	aeb->ec = ec;
574 	aeb->pnum = pnum;
575 	aeb->vol_id = vol_id;
576 	aeb->lnum = lnum;
577 	aeb->scrub = bitflips;
578 	aeb->copy_flag = vid_hdr->copy_flag;
579 	aeb->sqnum = sqnum;
580 
581 	if (av->highest_lnum <= lnum) {
582 		av->highest_lnum = lnum;
583 		av->last_data_size = be32_to_cpu(vid_hdr->data_size);
584 	}
585 
586 	av->leb_count += 1;
587 	rb_link_node(&aeb->u.rb, parent, p);
588 	rb_insert_color(&aeb->u.rb, &av->root);
589 	return 0;
590 }
591 
592 /**
593  * ubi_find_av - find volume in the attaching information.
594  * @ai: attaching information
595  * @vol_id: the requested volume ID
596  *
597  * This function returns a pointer to the volume description or %NULL if there
598  * are no data about this volume in the attaching information.
599  */
ubi_find_av(const struct ubi_attach_info * ai,int vol_id)600 struct ubi_ainf_volume *ubi_find_av(const struct ubi_attach_info *ai,
601 				    int vol_id)
602 {
603 	struct ubi_ainf_volume *av;
604 	struct rb_node *p = ai->volumes.rb_node;
605 
606 	while (p) {
607 		av = rb_entry(p, struct ubi_ainf_volume, rb);
608 
609 		if (vol_id == av->vol_id)
610 			return av;
611 
612 		if (vol_id > av->vol_id)
613 			p = p->rb_left;
614 		else
615 			p = p->rb_right;
616 	}
617 
618 	return NULL;
619 }
620 
621 /**
622  * ubi_remove_av - delete attaching information about a volume.
623  * @ai: attaching information
624  * @av: the volume attaching information to delete
625  */
ubi_remove_av(struct ubi_attach_info * ai,struct ubi_ainf_volume * av)626 void ubi_remove_av(struct ubi_attach_info *ai, struct ubi_ainf_volume *av)
627 {
628 	struct rb_node *rb;
629 	struct ubi_ainf_peb *aeb;
630 
631 	dbg_bld("remove attaching information about volume %d", av->vol_id);
632 
633 	while ((rb = rb_first(&av->root))) {
634 		aeb = rb_entry(rb, struct ubi_ainf_peb, u.rb);
635 		rb_erase(&aeb->u.rb, &av->root);
636 		list_add_tail(&aeb->u.list, &ai->erase);
637 	}
638 
639 	rb_erase(&av->rb, &ai->volumes);
640 	kfree(av);
641 	ai->vols_found -= 1;
642 }
643 
644 /**
645  * early_erase_peb - erase a physical eraseblock.
646  * @ubi: UBI device description object
647  * @ai: attaching information
648  * @pnum: physical eraseblock number to erase;
649  * @ec: erase counter value to write (%UBI_UNKNOWN if it is unknown)
650  *
651  * This function erases physical eraseblock 'pnum', and writes the erase
652  * counter header to it. This function should only be used on UBI device
653  * initialization stages, when the EBA sub-system had not been yet initialized.
654  * This function returns zero in case of success and a negative error code in
655  * case of failure.
656  */
early_erase_peb(struct ubi_device * ubi,const struct ubi_attach_info * ai,int pnum,int ec)657 static int early_erase_peb(struct ubi_device *ubi,
658 			   const struct ubi_attach_info *ai, int pnum, int ec)
659 {
660 	int err;
661 	struct ubi_ec_hdr *ec_hdr;
662 
663 	if ((long long)ec >= UBI_MAX_ERASECOUNTER) {
664 		/*
665 		 * Erase counter overflow. Upgrade UBI and use 64-bit
666 		 * erase counters internally.
667 		 */
668 		ubi_err(ubi, "erase counter overflow at PEB %d, EC %d",
669 			pnum, ec);
670 		return -EINVAL;
671 	}
672 
673 	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
674 	if (!ec_hdr)
675 		return -ENOMEM;
676 
677 	ec_hdr->ec = cpu_to_be64(ec);
678 
679 	err = ubi_io_sync_erase(ubi, pnum, 0);
680 	if (err < 0)
681 		goto out_free;
682 
683 	err = ubi_io_write_ec_hdr(ubi, pnum, ec_hdr);
684 
685 out_free:
686 	kfree(ec_hdr);
687 	return err;
688 }
689 
690 /**
691  * ubi_early_get_peb - get a free physical eraseblock.
692  * @ubi: UBI device description object
693  * @ai: attaching information
694  *
695  * This function returns a free physical eraseblock. It is supposed to be
696  * called on the UBI initialization stages when the wear-leveling sub-system is
697  * not initialized yet. This function picks a physical eraseblocks from one of
698  * the lists, writes the EC header if it is needed, and removes it from the
699  * list.
700  *
701  * This function returns a pointer to the "aeb" of the found free PEB in case
702  * of success and an error code in case of failure.
703  */
ubi_early_get_peb(struct ubi_device * ubi,struct ubi_attach_info * ai)704 struct ubi_ainf_peb *ubi_early_get_peb(struct ubi_device *ubi,
705 				       struct ubi_attach_info *ai)
706 {
707 	int err = 0;
708 	struct ubi_ainf_peb *aeb, *tmp_aeb;
709 
710 	if (!list_empty(&ai->free)) {
711 		aeb = list_entry(ai->free.next, struct ubi_ainf_peb, u.list);
712 		list_del(&aeb->u.list);
713 		dbg_bld("return free PEB %d, EC %d", aeb->pnum, aeb->ec);
714 		return aeb;
715 	}
716 
717 	/*
718 	 * We try to erase the first physical eraseblock from the erase list
719 	 * and pick it if we succeed, or try to erase the next one if not. And
720 	 * so forth. We don't want to take care about bad eraseblocks here -
721 	 * they'll be handled later.
722 	 */
723 	list_for_each_entry_safe(aeb, tmp_aeb, &ai->erase, u.list) {
724 		if (aeb->ec == UBI_UNKNOWN)
725 			aeb->ec = ai->mean_ec;
726 
727 		err = early_erase_peb(ubi, ai, aeb->pnum, aeb->ec+1);
728 		if (err)
729 			continue;
730 
731 		aeb->ec += 1;
732 		list_del(&aeb->u.list);
733 		dbg_bld("return PEB %d, EC %d", aeb->pnum, aeb->ec);
734 		return aeb;
735 	}
736 
737 	ubi_err(ubi, "no free eraseblocks");
738 	return ERR_PTR(-ENOSPC);
739 }
740 
741 /**
742  * check_corruption - check the data area of PEB.
743  * @ubi: UBI device description object
744  * @vid_hdr: the (corrupted) VID header of this PEB
745  * @pnum: the physical eraseblock number to check
746  *
747  * This is a helper function which is used to distinguish between VID header
748  * corruptions caused by power cuts and other reasons. If the PEB contains only
749  * 0xFF bytes in the data area, the VID header is most probably corrupted
750  * because of a power cut (%0 is returned in this case). Otherwise, it was
751  * probably corrupted for some other reasons (%1 is returned in this case). A
752  * negative error code is returned if a read error occurred.
753  *
754  * If the corruption reason was a power cut, UBI can safely erase this PEB.
755  * Otherwise, it should preserve it to avoid possibly destroying important
756  * information.
757  */
check_corruption(struct ubi_device * ubi,struct ubi_vid_hdr * vid_hdr,int pnum)758 static int check_corruption(struct ubi_device *ubi, struct ubi_vid_hdr *vid_hdr,
759 			    int pnum)
760 {
761 	int err;
762 
763 	mutex_lock(&ubi->buf_mutex);
764 	memset(ubi->peb_buf, 0x00, ubi->leb_size);
765 
766 	err = ubi_io_read(ubi, ubi->peb_buf, pnum, ubi->leb_start,
767 			  ubi->leb_size);
768 	if (err == UBI_IO_BITFLIPS || mtd_is_eccerr(err)) {
769 		/*
770 		 * Bit-flips or integrity errors while reading the data area.
771 		 * It is difficult to say for sure what type of corruption is
772 		 * this, but presumably a power cut happened while this PEB was
773 		 * erased, so it became unstable and corrupted, and should be
774 		 * erased.
775 		 */
776 		err = 0;
777 		goto out_unlock;
778 	}
779 
780 	if (err)
781 		goto out_unlock;
782 
783 	if (ubi_check_pattern(ubi->peb_buf, 0xFF, ubi->leb_size))
784 		goto out_unlock;
785 
786 	ubi_err(ubi, "PEB %d contains corrupted VID header, and the data does not contain all 0xFF",
787 		pnum);
788 	ubi_err(ubi, "this may be a non-UBI PEB or a severe VID header corruption which requires manual inspection");
789 	ubi_dump_vid_hdr(vid_hdr);
790 	pr_err("hexdump of PEB %d offset %d, length %d",
791 	       pnum, ubi->leb_start, ubi->leb_size);
792 	ubi_dbg_print_hex_dump("", DUMP_PREFIX_OFFSET, 32, 1,
793 			       ubi->peb_buf, ubi->leb_size, 1);
794 	err = 1;
795 
796 out_unlock:
797 	mutex_unlock(&ubi->buf_mutex);
798 	return err;
799 }
800 
801 /**
802  * scan_peb - scan and process UBI headers of a PEB.
803  * @ubi: UBI device description object
804  * @ai: attaching information
805  * @pnum: the physical eraseblock number
806  * @vid: The volume ID of the found volume will be stored in this pointer
807  * @sqnum: The sqnum of the found volume will be stored in this pointer
808  *
809  * This function reads UBI headers of PEB @pnum, checks them, and adds
810  * information about this PEB to the corresponding list or RB-tree in the
811  * "attaching info" structure. Returns zero if the physical eraseblock was
812  * successfully handled and a negative error code in case of failure.
813  */
scan_peb(struct ubi_device * ubi,struct ubi_attach_info * ai,int pnum,int * vid,unsigned long long * sqnum)814 static int scan_peb(struct ubi_device *ubi, struct ubi_attach_info *ai,
815 		    int pnum, int *vid, unsigned long long *sqnum)
816 {
817 	long long uninitialized_var(ec);
818 	int err, bitflips = 0, vol_id = -1, ec_err = 0;
819 
820 	dbg_bld("scan PEB %d", pnum);
821 
822 	/* Skip bad physical eraseblocks */
823 	err = ubi_io_is_bad(ubi, pnum);
824 	if (err < 0)
825 		return err;
826 	else if (err) {
827 		ai->bad_peb_count += 1;
828 		return 0;
829 	}
830 
831 	err = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
832 	if (err < 0)
833 		return err;
834 	switch (err) {
835 	case 0:
836 		break;
837 	case UBI_IO_BITFLIPS:
838 		bitflips = 1;
839 		break;
840 	case UBI_IO_FF:
841 		ai->empty_peb_count += 1;
842 		return add_to_list(ai, pnum, UBI_UNKNOWN, UBI_UNKNOWN,
843 				   UBI_UNKNOWN, 0, &ai->erase);
844 	case UBI_IO_FF_BITFLIPS:
845 		ai->empty_peb_count += 1;
846 		return add_to_list(ai, pnum, UBI_UNKNOWN, UBI_UNKNOWN,
847 				   UBI_UNKNOWN, 1, &ai->erase);
848 	case UBI_IO_BAD_HDR_EBADMSG:
849 	case UBI_IO_BAD_HDR:
850 		/*
851 		 * We have to also look at the VID header, possibly it is not
852 		 * corrupted. Set %bitflips flag in order to make this PEB be
853 		 * moved and EC be re-created.
854 		 */
855 		ec_err = err;
856 		ec = UBI_UNKNOWN;
857 		bitflips = 1;
858 		break;
859 	default:
860 		ubi_err(ubi, "'ubi_io_read_ec_hdr()' returned unknown code %d",
861 			err);
862 		return -EINVAL;
863 	}
864 
865 	if (!ec_err) {
866 		int image_seq;
867 
868 		/* Make sure UBI version is OK */
869 		if (ech->version != UBI_VERSION) {
870 			ubi_err(ubi, "this UBI version is %d, image version is %d",
871 				UBI_VERSION, (int)ech->version);
872 			return -EINVAL;
873 		}
874 
875 		ec = be64_to_cpu(ech->ec);
876 		if (ec > UBI_MAX_ERASECOUNTER) {
877 			/*
878 			 * Erase counter overflow. The EC headers have 64 bits
879 			 * reserved, but we anyway make use of only 31 bit
880 			 * values, as this seems to be enough for any existing
881 			 * flash. Upgrade UBI and use 64-bit erase counters
882 			 * internally.
883 			 */
884 			ubi_err(ubi, "erase counter overflow, max is %d",
885 				UBI_MAX_ERASECOUNTER);
886 			ubi_dump_ec_hdr(ech);
887 			return -EINVAL;
888 		}
889 
890 		/*
891 		 * Make sure that all PEBs have the same image sequence number.
892 		 * This allows us to detect situations when users flash UBI
893 		 * images incorrectly, so that the flash has the new UBI image
894 		 * and leftovers from the old one. This feature was added
895 		 * relatively recently, and the sequence number was always
896 		 * zero, because old UBI implementations always set it to zero.
897 		 * For this reasons, we do not panic if some PEBs have zero
898 		 * sequence number, while other PEBs have non-zero sequence
899 		 * number.
900 		 */
901 		image_seq = be32_to_cpu(ech->image_seq);
902 		if (!ubi->image_seq)
903 			ubi->image_seq = image_seq;
904 		if (image_seq && ubi->image_seq != image_seq) {
905 			ubi_err(ubi, "bad image sequence number %d in PEB %d, expected %d",
906 				image_seq, pnum, ubi->image_seq);
907 			ubi_dump_ec_hdr(ech);
908 			return -EINVAL;
909 		}
910 	}
911 
912 	/* OK, we've done with the EC header, let's look at the VID header */
913 
914 	err = ubi_io_read_vid_hdr(ubi, pnum, vidh, 0);
915 	if (err < 0)
916 		return err;
917 	switch (err) {
918 	case 0:
919 		break;
920 	case UBI_IO_BITFLIPS:
921 		bitflips = 1;
922 		break;
923 	case UBI_IO_BAD_HDR_EBADMSG:
924 		if (ec_err == UBI_IO_BAD_HDR_EBADMSG)
925 			/*
926 			 * Both EC and VID headers are corrupted and were read
927 			 * with data integrity error, probably this is a bad
928 			 * PEB, bit it is not marked as bad yet. This may also
929 			 * be a result of power cut during erasure.
930 			 */
931 			ai->maybe_bad_peb_count += 1;
932 	case UBI_IO_BAD_HDR:
933 		if (ec_err)
934 			/*
935 			 * Both headers are corrupted. There is a possibility
936 			 * that this a valid UBI PEB which has corresponding
937 			 * LEB, but the headers are corrupted. However, it is
938 			 * impossible to distinguish it from a PEB which just
939 			 * contains garbage because of a power cut during erase
940 			 * operation. So we just schedule this PEB for erasure.
941 			 *
942 			 * Besides, in case of NOR flash, we deliberately
943 			 * corrupt both headers because NOR flash erasure is
944 			 * slow and can start from the end.
945 			 */
946 			err = 0;
947 		else
948 			/*
949 			 * The EC was OK, but the VID header is corrupted. We
950 			 * have to check what is in the data area.
951 			 */
952 			err = check_corruption(ubi, vidh, pnum);
953 
954 		if (err < 0)
955 			return err;
956 		else if (!err)
957 			/* This corruption is caused by a power cut */
958 			err = add_to_list(ai, pnum, UBI_UNKNOWN,
959 					  UBI_UNKNOWN, ec, 1, &ai->erase);
960 		else
961 			/* This is an unexpected corruption */
962 			err = add_corrupted(ai, pnum, ec);
963 		if (err)
964 			return err;
965 		goto adjust_mean_ec;
966 	case UBI_IO_FF_BITFLIPS:
967 		err = add_to_list(ai, pnum, UBI_UNKNOWN, UBI_UNKNOWN,
968 				  ec, 1, &ai->erase);
969 		if (err)
970 			return err;
971 		goto adjust_mean_ec;
972 	case UBI_IO_FF:
973 		if (ec_err || bitflips)
974 			err = add_to_list(ai, pnum, UBI_UNKNOWN,
975 					  UBI_UNKNOWN, ec, 1, &ai->erase);
976 		else
977 			err = add_to_list(ai, pnum, UBI_UNKNOWN,
978 					  UBI_UNKNOWN, ec, 0, &ai->free);
979 		if (err)
980 			return err;
981 		goto adjust_mean_ec;
982 	default:
983 		ubi_err(ubi, "'ubi_io_read_vid_hdr()' returned unknown code %d",
984 			err);
985 		return -EINVAL;
986 	}
987 
988 	vol_id = be32_to_cpu(vidh->vol_id);
989 	if (vid)
990 		*vid = vol_id;
991 	if (sqnum)
992 		*sqnum = be64_to_cpu(vidh->sqnum);
993 	if (vol_id > UBI_MAX_VOLUMES && vol_id != UBI_LAYOUT_VOLUME_ID) {
994 		int lnum = be32_to_cpu(vidh->lnum);
995 
996 		/* Unsupported internal volume */
997 		switch (vidh->compat) {
998 		case UBI_COMPAT_DELETE:
999 			if (vol_id != UBI_FM_SB_VOLUME_ID
1000 			    && vol_id != UBI_FM_DATA_VOLUME_ID) {
1001 				ubi_msg(ubi, "\"delete\" compatible internal volume %d:%d found, will remove it",
1002 					vol_id, lnum);
1003 			}
1004 			err = add_to_list(ai, pnum, vol_id, lnum,
1005 					  ec, 1, &ai->erase);
1006 			if (err)
1007 				return err;
1008 			return 0;
1009 
1010 		case UBI_COMPAT_RO:
1011 			ubi_msg(ubi, "read-only compatible internal volume %d:%d found, switch to read-only mode",
1012 				vol_id, lnum);
1013 			ubi->ro_mode = 1;
1014 			break;
1015 
1016 		case UBI_COMPAT_PRESERVE:
1017 			ubi_msg(ubi, "\"preserve\" compatible internal volume %d:%d found",
1018 				vol_id, lnum);
1019 			err = add_to_list(ai, pnum, vol_id, lnum,
1020 					  ec, 0, &ai->alien);
1021 			if (err)
1022 				return err;
1023 			return 0;
1024 
1025 		case UBI_COMPAT_REJECT:
1026 			ubi_err(ubi, "incompatible internal volume %d:%d found",
1027 				vol_id, lnum);
1028 			return -EINVAL;
1029 		}
1030 	}
1031 
1032 	if (ec_err)
1033 		ubi_warn(ubi, "valid VID header but corrupted EC header at PEB %d",
1034 			 pnum);
1035 	err = ubi_add_to_av(ubi, ai, pnum, ec, vidh, bitflips);
1036 	if (err)
1037 		return err;
1038 
1039 adjust_mean_ec:
1040 	if (!ec_err) {
1041 		ai->ec_sum += ec;
1042 		ai->ec_count += 1;
1043 		if (ec > ai->max_ec)
1044 			ai->max_ec = ec;
1045 		if (ec < ai->min_ec)
1046 			ai->min_ec = ec;
1047 	}
1048 
1049 	return 0;
1050 }
1051 
1052 /**
1053  * late_analysis - analyze the overall situation with PEB.
1054  * @ubi: UBI device description object
1055  * @ai: attaching information
1056  *
1057  * This is a helper function which takes a look what PEBs we have after we
1058  * gather information about all of them ("ai" is compete). It decides whether
1059  * the flash is empty and should be formatted of whether there are too many
1060  * corrupted PEBs and we should not attach this MTD device. Returns zero if we
1061  * should proceed with attaching the MTD device, and %-EINVAL if we should not.
1062  */
late_analysis(struct ubi_device * ubi,struct ubi_attach_info * ai)1063 static int late_analysis(struct ubi_device *ubi, struct ubi_attach_info *ai)
1064 {
1065 	struct ubi_ainf_peb *aeb;
1066 	int max_corr, peb_count;
1067 
1068 	peb_count = ubi->peb_count - ai->bad_peb_count - ai->alien_peb_count;
1069 	max_corr = peb_count / 20 ?: 8;
1070 
1071 	/*
1072 	 * Few corrupted PEBs is not a problem and may be just a result of
1073 	 * unclean reboots. However, many of them may indicate some problems
1074 	 * with the flash HW or driver.
1075 	 */
1076 	if (ai->corr_peb_count) {
1077 		ubi_err(ubi, "%d PEBs are corrupted and preserved",
1078 			ai->corr_peb_count);
1079 		pr_err("Corrupted PEBs are:");
1080 		list_for_each_entry(aeb, &ai->corr, u.list)
1081 			pr_cont(" %d", aeb->pnum);
1082 		pr_cont("\n");
1083 
1084 		/*
1085 		 * If too many PEBs are corrupted, we refuse attaching,
1086 		 * otherwise, only print a warning.
1087 		 */
1088 		if (ai->corr_peb_count >= max_corr) {
1089 			ubi_err(ubi, "too many corrupted PEBs, refusing");
1090 			return -EINVAL;
1091 		}
1092 	}
1093 
1094 	if (ai->empty_peb_count + ai->maybe_bad_peb_count == peb_count) {
1095 		/*
1096 		 * All PEBs are empty, or almost all - a couple PEBs look like
1097 		 * they may be bad PEBs which were not marked as bad yet.
1098 		 *
1099 		 * This piece of code basically tries to distinguish between
1100 		 * the following situations:
1101 		 *
1102 		 * 1. Flash is empty, but there are few bad PEBs, which are not
1103 		 *    marked as bad so far, and which were read with error. We
1104 		 *    want to go ahead and format this flash. While formatting,
1105 		 *    the faulty PEBs will probably be marked as bad.
1106 		 *
1107 		 * 2. Flash contains non-UBI data and we do not want to format
1108 		 *    it and destroy possibly important information.
1109 		 */
1110 		if (ai->maybe_bad_peb_count <= 2) {
1111 			ai->is_empty = 1;
1112 			ubi_msg(ubi, "empty MTD device detected");
1113 			get_random_bytes(&ubi->image_seq,
1114 					 sizeof(ubi->image_seq));
1115 		} else {
1116 			ubi_err(ubi, "MTD device is not UBI-formatted and possibly contains non-UBI data - refusing it");
1117 			return -EINVAL;
1118 		}
1119 
1120 	}
1121 
1122 	return 0;
1123 }
1124 
1125 /**
1126  * destroy_av - free volume attaching information.
1127  * @av: volume attaching information
1128  * @ai: attaching information
1129  *
1130  * This function destroys the volume attaching information.
1131  */
destroy_av(struct ubi_attach_info * ai,struct ubi_ainf_volume * av)1132 static void destroy_av(struct ubi_attach_info *ai, struct ubi_ainf_volume *av)
1133 {
1134 	struct ubi_ainf_peb *aeb;
1135 	struct rb_node *this = av->root.rb_node;
1136 
1137 	while (this) {
1138 		if (this->rb_left)
1139 			this = this->rb_left;
1140 		else if (this->rb_right)
1141 			this = this->rb_right;
1142 		else {
1143 			aeb = rb_entry(this, struct ubi_ainf_peb, u.rb);
1144 			this = rb_parent(this);
1145 			if (this) {
1146 				if (this->rb_left == &aeb->u.rb)
1147 					this->rb_left = NULL;
1148 				else
1149 					this->rb_right = NULL;
1150 			}
1151 
1152 			kmem_cache_free(ai->aeb_slab_cache, aeb);
1153 		}
1154 	}
1155 	kfree(av);
1156 }
1157 
1158 /**
1159  * destroy_ai - destroy attaching information.
1160  * @ai: attaching information
1161  */
destroy_ai(struct ubi_attach_info * ai)1162 static void destroy_ai(struct ubi_attach_info *ai)
1163 {
1164 	struct ubi_ainf_peb *aeb, *aeb_tmp;
1165 	struct ubi_ainf_volume *av;
1166 	struct rb_node *rb;
1167 
1168 	list_for_each_entry_safe(aeb, aeb_tmp, &ai->alien, u.list) {
1169 		list_del(&aeb->u.list);
1170 		kmem_cache_free(ai->aeb_slab_cache, aeb);
1171 	}
1172 	list_for_each_entry_safe(aeb, aeb_tmp, &ai->erase, u.list) {
1173 		list_del(&aeb->u.list);
1174 		kmem_cache_free(ai->aeb_slab_cache, aeb);
1175 	}
1176 	list_for_each_entry_safe(aeb, aeb_tmp, &ai->corr, u.list) {
1177 		list_del(&aeb->u.list);
1178 		kmem_cache_free(ai->aeb_slab_cache, aeb);
1179 	}
1180 	list_for_each_entry_safe(aeb, aeb_tmp, &ai->free, u.list) {
1181 		list_del(&aeb->u.list);
1182 		kmem_cache_free(ai->aeb_slab_cache, aeb);
1183 	}
1184 
1185 	/* Destroy the volume RB-tree */
1186 	rb = ai->volumes.rb_node;
1187 	while (rb) {
1188 		if (rb->rb_left)
1189 			rb = rb->rb_left;
1190 		else if (rb->rb_right)
1191 			rb = rb->rb_right;
1192 		else {
1193 			av = rb_entry(rb, struct ubi_ainf_volume, rb);
1194 
1195 			rb = rb_parent(rb);
1196 			if (rb) {
1197 				if (rb->rb_left == &av->rb)
1198 					rb->rb_left = NULL;
1199 				else
1200 					rb->rb_right = NULL;
1201 			}
1202 
1203 			destroy_av(ai, av);
1204 		}
1205 	}
1206 
1207 	kmem_cache_destroy(ai->aeb_slab_cache);
1208 
1209 	kfree(ai);
1210 }
1211 
1212 /**
1213  * scan_all - scan entire MTD device.
1214  * @ubi: UBI device description object
1215  * @ai: attach info object
1216  * @start: start scanning at this PEB
1217  *
1218  * This function does full scanning of an MTD device and returns complete
1219  * information about it in form of a "struct ubi_attach_info" object. In case
1220  * of failure, an error code is returned.
1221  */
scan_all(struct ubi_device * ubi,struct ubi_attach_info * ai,int start)1222 static int scan_all(struct ubi_device *ubi, struct ubi_attach_info *ai,
1223 		    int start)
1224 {
1225 	int err, pnum;
1226 	struct rb_node *rb1, *rb2;
1227 	struct ubi_ainf_volume *av;
1228 	struct ubi_ainf_peb *aeb;
1229 
1230 	err = -ENOMEM;
1231 
1232 	ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
1233 	if (!ech)
1234 		return err;
1235 
1236 	vidh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
1237 	if (!vidh)
1238 		goto out_ech;
1239 
1240 	for (pnum = start; pnum < ubi->peb_count; pnum++) {
1241 		cond_resched();
1242 
1243 		dbg_gen("process PEB %d", pnum);
1244 		err = scan_peb(ubi, ai, pnum, NULL, NULL);
1245 		if (err < 0)
1246 			goto out_vidh;
1247 	}
1248 
1249 	ubi_msg(ubi, "scanning is finished");
1250 
1251 	/* Calculate mean erase counter */
1252 	if (ai->ec_count)
1253 		ai->mean_ec = div_u64(ai->ec_sum, ai->ec_count);
1254 
1255 	err = late_analysis(ubi, ai);
1256 	if (err)
1257 		goto out_vidh;
1258 
1259 	/*
1260 	 * In case of unknown erase counter we use the mean erase counter
1261 	 * value.
1262 	 */
1263 	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
1264 		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb)
1265 			if (aeb->ec == UBI_UNKNOWN)
1266 				aeb->ec = ai->mean_ec;
1267 	}
1268 
1269 	list_for_each_entry(aeb, &ai->free, u.list) {
1270 		if (aeb->ec == UBI_UNKNOWN)
1271 			aeb->ec = ai->mean_ec;
1272 	}
1273 
1274 	list_for_each_entry(aeb, &ai->corr, u.list)
1275 		if (aeb->ec == UBI_UNKNOWN)
1276 			aeb->ec = ai->mean_ec;
1277 
1278 	list_for_each_entry(aeb, &ai->erase, u.list)
1279 		if (aeb->ec == UBI_UNKNOWN)
1280 			aeb->ec = ai->mean_ec;
1281 
1282 	err = self_check_ai(ubi, ai);
1283 	if (err)
1284 		goto out_vidh;
1285 
1286 	ubi_free_vid_hdr(ubi, vidh);
1287 	kfree(ech);
1288 
1289 	return 0;
1290 
1291 out_vidh:
1292 	ubi_free_vid_hdr(ubi, vidh);
1293 out_ech:
1294 	kfree(ech);
1295 	return err;
1296 }
1297 
alloc_ai(void)1298 static struct ubi_attach_info *alloc_ai(void)
1299 {
1300 	struct ubi_attach_info *ai;
1301 
1302 	ai = kzalloc(sizeof(struct ubi_attach_info), GFP_KERNEL);
1303 	if (!ai)
1304 		return ai;
1305 
1306 	INIT_LIST_HEAD(&ai->corr);
1307 	INIT_LIST_HEAD(&ai->free);
1308 	INIT_LIST_HEAD(&ai->erase);
1309 	INIT_LIST_HEAD(&ai->alien);
1310 	ai->volumes = RB_ROOT;
1311 	ai->aeb_slab_cache = kmem_cache_create("ubi_aeb_slab_cache",
1312 					       sizeof(struct ubi_ainf_peb),
1313 					       0, 0, NULL);
1314 	if (!ai->aeb_slab_cache) {
1315 		kfree(ai);
1316 		ai = NULL;
1317 	}
1318 
1319 	return ai;
1320 }
1321 
1322 #ifdef CONFIG_MTD_UBI_FASTMAP
1323 
1324 /**
1325  * scan_fastmap - try to find a fastmap and attach from it.
1326  * @ubi: UBI device description object
1327  * @ai: attach info object
1328  *
1329  * Returns 0 on success, negative return values indicate an internal
1330  * error.
1331  * UBI_NO_FASTMAP denotes that no fastmap was found.
1332  * UBI_BAD_FASTMAP denotes that the found fastmap was invalid.
1333  */
scan_fast(struct ubi_device * ubi,struct ubi_attach_info ** ai)1334 static int scan_fast(struct ubi_device *ubi, struct ubi_attach_info **ai)
1335 {
1336 	int err, pnum, fm_anchor = -1;
1337 	unsigned long long max_sqnum = 0;
1338 
1339 	err = -ENOMEM;
1340 
1341 	ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
1342 	if (!ech)
1343 		goto out;
1344 
1345 	vidh = ubi_zalloc_vid_hdr(ubi, GFP_KERNEL);
1346 	if (!vidh)
1347 		goto out_ech;
1348 
1349 	for (pnum = 0; pnum < UBI_FM_MAX_START; pnum++) {
1350 		int vol_id = -1;
1351 		unsigned long long sqnum = -1;
1352 		cond_resched();
1353 
1354 		dbg_gen("process PEB %d", pnum);
1355 		err = scan_peb(ubi, *ai, pnum, &vol_id, &sqnum);
1356 		if (err < 0)
1357 			goto out_vidh;
1358 
1359 		if (vol_id == UBI_FM_SB_VOLUME_ID && sqnum > max_sqnum) {
1360 			max_sqnum = sqnum;
1361 			fm_anchor = pnum;
1362 		}
1363 	}
1364 
1365 	ubi_free_vid_hdr(ubi, vidh);
1366 	kfree(ech);
1367 
1368 	if (fm_anchor < 0)
1369 		return UBI_NO_FASTMAP;
1370 
1371 	destroy_ai(*ai);
1372 	*ai = alloc_ai();
1373 	if (!*ai)
1374 		return -ENOMEM;
1375 
1376 	return ubi_scan_fastmap(ubi, *ai, fm_anchor);
1377 
1378 out_vidh:
1379 	ubi_free_vid_hdr(ubi, vidh);
1380 out_ech:
1381 	kfree(ech);
1382 out:
1383 	return err;
1384 }
1385 
1386 #endif
1387 
1388 /**
1389  * ubi_attach - attach an MTD device.
1390  * @ubi: UBI device descriptor
1391  * @force_scan: if set to non-zero attach by scanning
1392  *
1393  * This function returns zero in case of success and a negative error code in
1394  * case of failure.
1395  */
ubi_attach(struct ubi_device * ubi,int force_scan)1396 int ubi_attach(struct ubi_device *ubi, int force_scan)
1397 {
1398 	int err;
1399 	struct ubi_attach_info *ai;
1400 
1401 	ai = alloc_ai();
1402 	if (!ai)
1403 		return -ENOMEM;
1404 
1405 #ifdef CONFIG_MTD_UBI_FASTMAP
1406 	/* On small flash devices we disable fastmap in any case. */
1407 	if ((int)mtd_div_by_eb(ubi->mtd->size, ubi->mtd) <= UBI_FM_MAX_START) {
1408 		ubi->fm_disabled = 1;
1409 		force_scan = 1;
1410 	}
1411 
1412 	if (force_scan)
1413 		err = scan_all(ubi, ai, 0);
1414 	else {
1415 		err = scan_fast(ubi, &ai);
1416 		if (err > 0 || mtd_is_eccerr(err)) {
1417 			if (err != UBI_NO_FASTMAP) {
1418 				destroy_ai(ai);
1419 				ai = alloc_ai();
1420 				if (!ai)
1421 					return -ENOMEM;
1422 
1423 				err = scan_all(ubi, ai, 0);
1424 			} else {
1425 				err = scan_all(ubi, ai, UBI_FM_MAX_START);
1426 			}
1427 		}
1428 	}
1429 #else
1430 	err = scan_all(ubi, ai, 0);
1431 #endif
1432 	if (err)
1433 		goto out_ai;
1434 
1435 	ubi->bad_peb_count = ai->bad_peb_count;
1436 	ubi->good_peb_count = ubi->peb_count - ubi->bad_peb_count;
1437 	ubi->corr_peb_count = ai->corr_peb_count;
1438 	ubi->max_ec = ai->max_ec;
1439 	ubi->mean_ec = ai->mean_ec;
1440 	dbg_gen("max. sequence number:       %llu", ai->max_sqnum);
1441 
1442 	err = ubi_read_volume_table(ubi, ai);
1443 	if (err)
1444 		goto out_ai;
1445 
1446 	err = ubi_wl_init(ubi, ai);
1447 	if (err)
1448 		goto out_vtbl;
1449 
1450 	err = ubi_eba_init(ubi, ai);
1451 	if (err)
1452 		goto out_wl;
1453 
1454 #ifdef CONFIG_MTD_UBI_FASTMAP
1455 	if (ubi->fm && ubi_dbg_chk_fastmap(ubi)) {
1456 		struct ubi_attach_info *scan_ai;
1457 
1458 		scan_ai = alloc_ai();
1459 		if (!scan_ai) {
1460 			err = -ENOMEM;
1461 			goto out_wl;
1462 		}
1463 
1464 		err = scan_all(ubi, scan_ai, 0);
1465 		if (err) {
1466 			destroy_ai(scan_ai);
1467 			goto out_wl;
1468 		}
1469 
1470 		err = self_check_eba(ubi, ai, scan_ai);
1471 		destroy_ai(scan_ai);
1472 
1473 		if (err)
1474 			goto out_wl;
1475 	}
1476 #endif
1477 
1478 	destroy_ai(ai);
1479 	return 0;
1480 
1481 out_wl:
1482 	ubi_wl_close(ubi);
1483 out_vtbl:
1484 	ubi_free_internal_volumes(ubi);
1485 	vfree(ubi->vtbl);
1486 out_ai:
1487 	destroy_ai(ai);
1488 	return err;
1489 }
1490 
1491 /**
1492  * self_check_ai - check the attaching information.
1493  * @ubi: UBI device description object
1494  * @ai: attaching information
1495  *
1496  * This function returns zero if the attaching information is all right, and a
1497  * negative error code if not or if an error occurred.
1498  */
self_check_ai(struct ubi_device * ubi,struct ubi_attach_info * ai)1499 static int self_check_ai(struct ubi_device *ubi, struct ubi_attach_info *ai)
1500 {
1501 	int pnum, err, vols_found = 0;
1502 	struct rb_node *rb1, *rb2;
1503 	struct ubi_ainf_volume *av;
1504 	struct ubi_ainf_peb *aeb, *last_aeb;
1505 	uint8_t *buf;
1506 
1507 	if (!ubi_dbg_chk_gen(ubi))
1508 		return 0;
1509 
1510 	/*
1511 	 * At first, check that attaching information is OK.
1512 	 */
1513 	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
1514 		int leb_count = 0;
1515 
1516 		cond_resched();
1517 
1518 		vols_found += 1;
1519 
1520 		if (ai->is_empty) {
1521 			ubi_err(ubi, "bad is_empty flag");
1522 			goto bad_av;
1523 		}
1524 
1525 		if (av->vol_id < 0 || av->highest_lnum < 0 ||
1526 		    av->leb_count < 0 || av->vol_type < 0 || av->used_ebs < 0 ||
1527 		    av->data_pad < 0 || av->last_data_size < 0) {
1528 			ubi_err(ubi, "negative values");
1529 			goto bad_av;
1530 		}
1531 
1532 		if (av->vol_id >= UBI_MAX_VOLUMES &&
1533 		    av->vol_id < UBI_INTERNAL_VOL_START) {
1534 			ubi_err(ubi, "bad vol_id");
1535 			goto bad_av;
1536 		}
1537 
1538 		if (av->vol_id > ai->highest_vol_id) {
1539 			ubi_err(ubi, "highest_vol_id is %d, but vol_id %d is there",
1540 				ai->highest_vol_id, av->vol_id);
1541 			goto out;
1542 		}
1543 
1544 		if (av->vol_type != UBI_DYNAMIC_VOLUME &&
1545 		    av->vol_type != UBI_STATIC_VOLUME) {
1546 			ubi_err(ubi, "bad vol_type");
1547 			goto bad_av;
1548 		}
1549 
1550 		if (av->data_pad > ubi->leb_size / 2) {
1551 			ubi_err(ubi, "bad data_pad");
1552 			goto bad_av;
1553 		}
1554 
1555 		last_aeb = NULL;
1556 		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb) {
1557 			cond_resched();
1558 
1559 			last_aeb = aeb;
1560 			leb_count += 1;
1561 
1562 			if (aeb->pnum < 0 || aeb->ec < 0) {
1563 				ubi_err(ubi, "negative values");
1564 				goto bad_aeb;
1565 			}
1566 
1567 			if (aeb->ec < ai->min_ec) {
1568 				ubi_err(ubi, "bad ai->min_ec (%d), %d found",
1569 					ai->min_ec, aeb->ec);
1570 				goto bad_aeb;
1571 			}
1572 
1573 			if (aeb->ec > ai->max_ec) {
1574 				ubi_err(ubi, "bad ai->max_ec (%d), %d found",
1575 					ai->max_ec, aeb->ec);
1576 				goto bad_aeb;
1577 			}
1578 
1579 			if (aeb->pnum >= ubi->peb_count) {
1580 				ubi_err(ubi, "too high PEB number %d, total PEBs %d",
1581 					aeb->pnum, ubi->peb_count);
1582 				goto bad_aeb;
1583 			}
1584 
1585 			if (av->vol_type == UBI_STATIC_VOLUME) {
1586 				if (aeb->lnum >= av->used_ebs) {
1587 					ubi_err(ubi, "bad lnum or used_ebs");
1588 					goto bad_aeb;
1589 				}
1590 			} else {
1591 				if (av->used_ebs != 0) {
1592 					ubi_err(ubi, "non-zero used_ebs");
1593 					goto bad_aeb;
1594 				}
1595 			}
1596 
1597 			if (aeb->lnum > av->highest_lnum) {
1598 				ubi_err(ubi, "incorrect highest_lnum or lnum");
1599 				goto bad_aeb;
1600 			}
1601 		}
1602 
1603 		if (av->leb_count != leb_count) {
1604 			ubi_err(ubi, "bad leb_count, %d objects in the tree",
1605 				leb_count);
1606 			goto bad_av;
1607 		}
1608 
1609 		if (!last_aeb)
1610 			continue;
1611 
1612 		aeb = last_aeb;
1613 
1614 		if (aeb->lnum != av->highest_lnum) {
1615 			ubi_err(ubi, "bad highest_lnum");
1616 			goto bad_aeb;
1617 		}
1618 	}
1619 
1620 	if (vols_found != ai->vols_found) {
1621 		ubi_err(ubi, "bad ai->vols_found %d, should be %d",
1622 			ai->vols_found, vols_found);
1623 		goto out;
1624 	}
1625 
1626 	/* Check that attaching information is correct */
1627 	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
1628 		last_aeb = NULL;
1629 		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb) {
1630 			int vol_type;
1631 
1632 			cond_resched();
1633 
1634 			last_aeb = aeb;
1635 
1636 			err = ubi_io_read_vid_hdr(ubi, aeb->pnum, vidh, 1);
1637 			if (err && err != UBI_IO_BITFLIPS) {
1638 				ubi_err(ubi, "VID header is not OK (%d)",
1639 					err);
1640 				if (err > 0)
1641 					err = -EIO;
1642 				return err;
1643 			}
1644 
1645 			vol_type = vidh->vol_type == UBI_VID_DYNAMIC ?
1646 				   UBI_DYNAMIC_VOLUME : UBI_STATIC_VOLUME;
1647 			if (av->vol_type != vol_type) {
1648 				ubi_err(ubi, "bad vol_type");
1649 				goto bad_vid_hdr;
1650 			}
1651 
1652 			if (aeb->sqnum != be64_to_cpu(vidh->sqnum)) {
1653 				ubi_err(ubi, "bad sqnum %llu", aeb->sqnum);
1654 				goto bad_vid_hdr;
1655 			}
1656 
1657 			if (av->vol_id != be32_to_cpu(vidh->vol_id)) {
1658 				ubi_err(ubi, "bad vol_id %d", av->vol_id);
1659 				goto bad_vid_hdr;
1660 			}
1661 
1662 			if (av->compat != vidh->compat) {
1663 				ubi_err(ubi, "bad compat %d", vidh->compat);
1664 				goto bad_vid_hdr;
1665 			}
1666 
1667 			if (aeb->lnum != be32_to_cpu(vidh->lnum)) {
1668 				ubi_err(ubi, "bad lnum %d", aeb->lnum);
1669 				goto bad_vid_hdr;
1670 			}
1671 
1672 			if (av->used_ebs != be32_to_cpu(vidh->used_ebs)) {
1673 				ubi_err(ubi, "bad used_ebs %d", av->used_ebs);
1674 				goto bad_vid_hdr;
1675 			}
1676 
1677 			if (av->data_pad != be32_to_cpu(vidh->data_pad)) {
1678 				ubi_err(ubi, "bad data_pad %d", av->data_pad);
1679 				goto bad_vid_hdr;
1680 			}
1681 		}
1682 
1683 		if (!last_aeb)
1684 			continue;
1685 
1686 		if (av->highest_lnum != be32_to_cpu(vidh->lnum)) {
1687 			ubi_err(ubi, "bad highest_lnum %d", av->highest_lnum);
1688 			goto bad_vid_hdr;
1689 		}
1690 
1691 		if (av->last_data_size != be32_to_cpu(vidh->data_size)) {
1692 			ubi_err(ubi, "bad last_data_size %d",
1693 				av->last_data_size);
1694 			goto bad_vid_hdr;
1695 		}
1696 	}
1697 
1698 	/*
1699 	 * Make sure that all the physical eraseblocks are in one of the lists
1700 	 * or trees.
1701 	 */
1702 	buf = kzalloc(ubi->peb_count, GFP_KERNEL);
1703 	if (!buf)
1704 		return -ENOMEM;
1705 
1706 	for (pnum = 0; pnum < ubi->peb_count; pnum++) {
1707 		err = ubi_io_is_bad(ubi, pnum);
1708 		if (err < 0) {
1709 			kfree(buf);
1710 			return err;
1711 		} else if (err)
1712 			buf[pnum] = 1;
1713 	}
1714 
1715 	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb)
1716 		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb)
1717 			buf[aeb->pnum] = 1;
1718 
1719 	list_for_each_entry(aeb, &ai->free, u.list)
1720 		buf[aeb->pnum] = 1;
1721 
1722 	list_for_each_entry(aeb, &ai->corr, u.list)
1723 		buf[aeb->pnum] = 1;
1724 
1725 	list_for_each_entry(aeb, &ai->erase, u.list)
1726 		buf[aeb->pnum] = 1;
1727 
1728 	list_for_each_entry(aeb, &ai->alien, u.list)
1729 		buf[aeb->pnum] = 1;
1730 
1731 	err = 0;
1732 	for (pnum = 0; pnum < ubi->peb_count; pnum++)
1733 		if (!buf[pnum]) {
1734 			ubi_err(ubi, "PEB %d is not referred", pnum);
1735 			err = 1;
1736 		}
1737 
1738 	kfree(buf);
1739 	if (err)
1740 		goto out;
1741 	return 0;
1742 
1743 bad_aeb:
1744 	ubi_err(ubi, "bad attaching information about LEB %d", aeb->lnum);
1745 	ubi_dump_aeb(aeb, 0);
1746 	ubi_dump_av(av);
1747 	goto out;
1748 
1749 bad_av:
1750 	ubi_err(ubi, "bad attaching information about volume %d", av->vol_id);
1751 	ubi_dump_av(av);
1752 	goto out;
1753 
1754 bad_vid_hdr:
1755 	ubi_err(ubi, "bad attaching information about volume %d", av->vol_id);
1756 	ubi_dump_av(av);
1757 	ubi_dump_vid_hdr(vidh);
1758 
1759 out:
1760 	dump_stack();
1761 	return -EINVAL;
1762 }
1763