1/*
2 * lib/bitmap.c
3 * Helper functions for bitmap.h.
4 *
5 * This source code is licensed under the GNU General Public License,
6 * Version 2. See the file COPYING for more details.
7 */
8#include <linux/export.h>
9#include <linux/thread_info.h>
10#include <linux/ctype.h>
11#include <linux/errno.h>
12#include <linux/bitmap.h>
13#include <linux/bitops.h>
14#include <linux/bug.h>
15#include <linux/kernel.h>
16#include <linux/mm.h>
17#include <linux/slab.h>
18#include <linux/string.h>
19#include <linux/uaccess.h>
20
21#include <asm/page.h>
22
23/**
24 * DOC: bitmap introduction
25 *
26 * bitmaps provide an array of bits, implemented using an an
27 * array of unsigned longs. The number of valid bits in a
28 * given bitmap does _not_ need to be an exact multiple of
29 * BITS_PER_LONG.
30 *
31 * The possible unused bits in the last, partially used word
32 * of a bitmap are 'don't care'. The implementation makes
33 * no particular effort to keep them zero. It ensures that
34 * their value will not affect the results of any operation.
35 * The bitmap operations that return Boolean (bitmap_empty,
36 * for example) or scalar (bitmap_weight, for example) results
37 * carefully filter out these unused bits from impacting their
38 * results.
39 *
40 * The byte ordering of bitmaps is more natural on little
41 * endian architectures. See the big-endian headers
42 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
43 * for the best explanations of this ordering.
44 */
45
46int __bitmap_equal(const unsigned long *bitmap1,
47 const unsigned long *bitmap2, unsigned int bits)
48{
49 unsigned int k, lim = bits/BITS_PER_LONG;
50 for (k = 0; k < lim; ++k)
51 if (bitmap1[k] != bitmap2[k])
52 return 0;
53
54 if (bits % BITS_PER_LONG)
55 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
56 return 0;
57
58 return 1;
59}
60EXPORT_SYMBOL(__bitmap_equal);
61
62void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
63{
64 unsigned int k, lim = BITS_TO_LONGS(bits);
65 for (k = 0; k < lim; ++k)
66 dst[k] = ~src[k];
67}
68EXPORT_SYMBOL(__bitmap_complement);
69
70/**
71 * __bitmap_shift_right - logical right shift of the bits in a bitmap
72 * @dst : destination bitmap
73 * @src : source bitmap
74 * @shift : shift by this many bits
75 * @nbits : bitmap size, in bits
76 *
77 * Shifting right (dividing) means moving bits in the MS -> LS bit
78 * direction. Zeros are fed into the vacated MS positions and the
79 * LS bits shifted off the bottom are lost.
80 */
81void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
82 unsigned shift, unsigned nbits)
83{
84 unsigned k, lim = BITS_TO_LONGS(nbits);
85 unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
86 unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
87 for (k = 0; off + k < lim; ++k) {
88 unsigned long upper, lower;
89
90 /*
91 * If shift is not word aligned, take lower rem bits of
92 * word above and make them the top rem bits of result.
93 */
94 if (!rem || off + k + 1 >= lim)
95 upper = 0;
96 else {
97 upper = src[off + k + 1];
98 if (off + k + 1 == lim - 1)
99 upper &= mask;
100 upper <<= (BITS_PER_LONG - rem);
101 }
102 lower = src[off + k];
103 if (off + k == lim - 1)
104 lower &= mask;
105 lower >>= rem;
106 dst[k] = lower | upper;
107 }
108 if (off)
109 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
110}
111EXPORT_SYMBOL(__bitmap_shift_right);
112
113
114/**
115 * __bitmap_shift_left - logical left shift of the bits in a bitmap
116 * @dst : destination bitmap
117 * @src : source bitmap
118 * @shift : shift by this many bits
119 * @nbits : bitmap size, in bits
120 *
121 * Shifting left (multiplying) means moving bits in the LS -> MS
122 * direction. Zeros are fed into the vacated LS bit positions
123 * and those MS bits shifted off the top are lost.
124 */
125
126void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
127 unsigned int shift, unsigned int nbits)
128{
129 int k;
130 unsigned int lim = BITS_TO_LONGS(nbits);
131 unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
132 for (k = lim - off - 1; k >= 0; --k) {
133 unsigned long upper, lower;
134
135 /*
136 * If shift is not word aligned, take upper rem bits of
137 * word below and make them the bottom rem bits of result.
138 */
139 if (rem && k > 0)
140 lower = src[k - 1] >> (BITS_PER_LONG - rem);
141 else
142 lower = 0;
143 upper = src[k] << rem;
144 dst[k + off] = lower | upper;
145 }
146 if (off)
147 memset(dst, 0, off*sizeof(unsigned long));
148}
149EXPORT_SYMBOL(__bitmap_shift_left);
150
151int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
152 const unsigned long *bitmap2, unsigned int bits)
153{
154 unsigned int k;
155 unsigned int lim = bits/BITS_PER_LONG;
156 unsigned long result = 0;
157
158 for (k = 0; k < lim; k++)
159 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
160 if (bits % BITS_PER_LONG)
161 result |= (dst[k] = bitmap1[k] & bitmap2[k] &
162 BITMAP_LAST_WORD_MASK(bits));
163 return result != 0;
164}
165EXPORT_SYMBOL(__bitmap_and);
166
167void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
168 const unsigned long *bitmap2, unsigned int bits)
169{
170 unsigned int k;
171 unsigned int nr = BITS_TO_LONGS(bits);
172
173 for (k = 0; k < nr; k++)
174 dst[k] = bitmap1[k] | bitmap2[k];
175}
176EXPORT_SYMBOL(__bitmap_or);
177
178void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
179 const unsigned long *bitmap2, unsigned int bits)
180{
181 unsigned int k;
182 unsigned int nr = BITS_TO_LONGS(bits);
183
184 for (k = 0; k < nr; k++)
185 dst[k] = bitmap1[k] ^ bitmap2[k];
186}
187EXPORT_SYMBOL(__bitmap_xor);
188
189int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
190 const unsigned long *bitmap2, unsigned int bits)
191{
192 unsigned int k;
193 unsigned int lim = bits/BITS_PER_LONG;
194 unsigned long result = 0;
195
196 for (k = 0; k < lim; k++)
197 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
198 if (bits % BITS_PER_LONG)
199 result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
200 BITMAP_LAST_WORD_MASK(bits));
201 return result != 0;
202}
203EXPORT_SYMBOL(__bitmap_andnot);
204
205int __bitmap_intersects(const unsigned long *bitmap1,
206 const unsigned long *bitmap2, unsigned int bits)
207{
208 unsigned int k, lim = bits/BITS_PER_LONG;
209 for (k = 0; k < lim; ++k)
210 if (bitmap1[k] & bitmap2[k])
211 return 1;
212
213 if (bits % BITS_PER_LONG)
214 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
215 return 1;
216 return 0;
217}
218EXPORT_SYMBOL(__bitmap_intersects);
219
220int __bitmap_subset(const unsigned long *bitmap1,
221 const unsigned long *bitmap2, unsigned int bits)
222{
223 unsigned int k, lim = bits/BITS_PER_LONG;
224 for (k = 0; k < lim; ++k)
225 if (bitmap1[k] & ~bitmap2[k])
226 return 0;
227
228 if (bits % BITS_PER_LONG)
229 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
230 return 0;
231 return 1;
232}
233EXPORT_SYMBOL(__bitmap_subset);
234
235int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
236{
237 unsigned int k, lim = bits/BITS_PER_LONG;
238 int w = 0;
239
240 for (k = 0; k < lim; k++)
241 w += hweight_long(bitmap[k]);
242
243 if (bits % BITS_PER_LONG)
244 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
245
246 return w;
247}
248EXPORT_SYMBOL(__bitmap_weight);
249
250void __bitmap_set(unsigned long *map, unsigned int start, int len)
251{
252 unsigned long *p = map + BIT_WORD(start);
253 const unsigned int size = start + len;
254 int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
255 unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
256
257 while (len - bits_to_set >= 0) {
258 *p |= mask_to_set;
259 len -= bits_to_set;
260 bits_to_set = BITS_PER_LONG;
261 mask_to_set = ~0UL;
262 p++;
263 }
264 if (len) {
265 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
266 *p |= mask_to_set;
267 }
268}
269EXPORT_SYMBOL(__bitmap_set);
270
271void __bitmap_clear(unsigned long *map, unsigned int start, int len)
272{
273 unsigned long *p = map + BIT_WORD(start);
274 const unsigned int size = start + len;
275 int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
276 unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
277
278 while (len - bits_to_clear >= 0) {
279 *p &= ~mask_to_clear;
280 len -= bits_to_clear;
281 bits_to_clear = BITS_PER_LONG;
282 mask_to_clear = ~0UL;
283 p++;
284 }
285 if (len) {
286 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
287 *p &= ~mask_to_clear;
288 }
289}
290EXPORT_SYMBOL(__bitmap_clear);
291
292/**
293 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
294 * @map: The address to base the search on
295 * @size: The bitmap size in bits
296 * @start: The bitnumber to start searching at
297 * @nr: The number of zeroed bits we're looking for
298 * @align_mask: Alignment mask for zero area
299 * @align_offset: Alignment offset for zero area.
300 *
301 * The @align_mask should be one less than a power of 2; the effect is that
302 * the bit offset of all zero areas this function finds plus @align_offset
303 * is multiple of that power of 2.
304 */
305unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
306 unsigned long size,
307 unsigned long start,
308 unsigned int nr,
309 unsigned long align_mask,
310 unsigned long align_offset)
311{
312 unsigned long index, end, i;
313again:
314 index = find_next_zero_bit(map, size, start);
315
316 /* Align allocation */
317 index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
318
319 end = index + nr;
320 if (end > size)
321 return end;
322 i = find_next_bit(map, end, index);
323 if (i < end) {
324 start = i + 1;
325 goto again;
326 }
327 return index;
328}
329EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
330
331/*
332 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
333 * second version by Paul Jackson, third by Joe Korty.
334 */
335
336#define CHUNKSZ 32
337#define nbits_to_hold_value(val) fls(val)
338#define BASEDEC 10 /* fancier cpuset lists input in decimal */
339
340/**
341 * __bitmap_parse - convert an ASCII hex string into a bitmap.
342 * @buf: pointer to buffer containing string.
343 * @buflen: buffer size in bytes. If string is smaller than this
344 * then it must be terminated with a \0.
345 * @is_user: location of buffer, 0 indicates kernel space
346 * @maskp: pointer to bitmap array that will contain result.
347 * @nmaskbits: size of bitmap, in bits.
348 *
349 * Commas group hex digits into chunks. Each chunk defines exactly 32
350 * bits of the resultant bitmask. No chunk may specify a value larger
351 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
352 * then leading 0-bits are prepended. %-EINVAL is returned for illegal
353 * characters and for grouping errors such as "1,,5", ",44", "," and "".
354 * Leading and trailing whitespace accepted, but not embedded whitespace.
355 */
356int __bitmap_parse(const char *buf, unsigned int buflen,
357 int is_user, unsigned long *maskp,
358 int nmaskbits)
359{
360 int c, old_c, totaldigits, ndigits, nchunks, nbits;
361 u32 chunk;
362 const char __user __force *ubuf = (const char __user __force *)buf;
363
364 bitmap_zero(maskp, nmaskbits);
365
366 nchunks = nbits = totaldigits = c = 0;
367 do {
368 chunk = 0;
369 ndigits = totaldigits;
370
371 /* Get the next chunk of the bitmap */
372 while (buflen) {
373 old_c = c;
374 if (is_user) {
375 if (__get_user(c, ubuf++))
376 return -EFAULT;
377 }
378 else
379 c = *buf++;
380 buflen--;
381 if (isspace(c))
382 continue;
383
384 /*
385 * If the last character was a space and the current
386 * character isn't '\0', we've got embedded whitespace.
387 * This is a no-no, so throw an error.
388 */
389 if (totaldigits && c && isspace(old_c))
390 return -EINVAL;
391
392 /* A '\0' or a ',' signal the end of the chunk */
393 if (c == '\0' || c == ',')
394 break;
395
396 if (!isxdigit(c))
397 return -EINVAL;
398
399 /*
400 * Make sure there are at least 4 free bits in 'chunk'.
401 * If not, this hexdigit will overflow 'chunk', so
402 * throw an error.
403 */
404 if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
405 return -EOVERFLOW;
406
407 chunk = (chunk << 4) | hex_to_bin(c);
408 totaldigits++;
409 }
410 if (ndigits == totaldigits)
411 return -EINVAL;
412 if (nchunks == 0 && chunk == 0)
413 continue;
414
415 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
416 *maskp |= chunk;
417 nchunks++;
418 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
419 if (nbits > nmaskbits)
420 return -EOVERFLOW;
421 } while (buflen && c == ',');
422
423 return 0;
424}
425EXPORT_SYMBOL(__bitmap_parse);
426
427/**
428 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
429 *
430 * @ubuf: pointer to user buffer containing string.
431 * @ulen: buffer size in bytes. If string is smaller than this
432 * then it must be terminated with a \0.
433 * @maskp: pointer to bitmap array that will contain result.
434 * @nmaskbits: size of bitmap, in bits.
435 *
436 * Wrapper for __bitmap_parse(), providing it with user buffer.
437 *
438 * We cannot have this as an inline function in bitmap.h because it needs
439 * linux/uaccess.h to get the access_ok() declaration and this causes
440 * cyclic dependencies.
441 */
442int bitmap_parse_user(const char __user *ubuf,
443 unsigned int ulen, unsigned long *maskp,
444 int nmaskbits)
445{
446 if (!access_ok(ubuf, ulen))
447 return -EFAULT;
448 return __bitmap_parse((const char __force *)ubuf,
449 ulen, 1, maskp, nmaskbits);
450
451}
452EXPORT_SYMBOL(bitmap_parse_user);
453
454/**
455 * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
456 * @list: indicates whether the bitmap must be list
457 * @buf: page aligned buffer into which string is placed
458 * @maskp: pointer to bitmap to convert
459 * @nmaskbits: size of bitmap, in bits
460 *
461 * Output format is a comma-separated list of decimal numbers and
462 * ranges if list is specified or hex digits grouped into comma-separated
463 * sets of 8 digits/set. Returns the number of characters written to buf.
464 *
465 * It is assumed that @buf is a pointer into a PAGE_SIZE, page-aligned
466 * area and that sufficient storage remains at @buf to accommodate the
467 * bitmap_print_to_pagebuf() output. Returns the number of characters
468 * actually printed to @buf, excluding terminating '\0'.
469 */
470int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
471 int nmaskbits)
472{
473 ptrdiff_t len = PAGE_SIZE - offset_in_page(buf);
474
475 return list ? scnprintf(buf, len, "%*pbl\n", nmaskbits, maskp) :
476 scnprintf(buf, len, "%*pb\n", nmaskbits, maskp);
477}
478EXPORT_SYMBOL(bitmap_print_to_pagebuf);
479
480/**
481 * __bitmap_parselist - convert list format ASCII string to bitmap
482 * @buf: read nul-terminated user string from this buffer
483 * @buflen: buffer size in bytes. If string is smaller than this
484 * then it must be terminated with a \0.
485 * @is_user: location of buffer, 0 indicates kernel space
486 * @maskp: write resulting mask here
487 * @nmaskbits: number of bits in mask to be written
488 *
489 * Input format is a comma-separated list of decimal numbers and
490 * ranges. Consecutively set bits are shown as two hyphen-separated
491 * decimal numbers, the smallest and largest bit numbers set in
492 * the range.
493 * Optionally each range can be postfixed to denote that only parts of it
494 * should be set. The range will divided to groups of specific size.
495 * From each group will be used only defined amount of bits.
496 * Syntax: range:used_size/group_size
497 * Example: 0-1023:2/256 ==> 0,1,256,257,512,513,768,769
498 *
499 * Returns: 0 on success, -errno on invalid input strings. Error values:
500 *
501 * - ``-EINVAL``: second number in range smaller than first
502 * - ``-EINVAL``: invalid character in string
503 * - ``-ERANGE``: bit number specified too large for mask
504 */
505static int __bitmap_parselist(const char *buf, unsigned int buflen,
506 int is_user, unsigned long *maskp,
507 int nmaskbits)
508{
509 unsigned int a, b, old_a, old_b;
510 unsigned int group_size, used_size, off;
511 int c, old_c, totaldigits, ndigits;
512 const char __user __force *ubuf = (const char __user __force *)buf;
513 int at_start, in_range, in_partial_range;
514
515 totaldigits = c = 0;
516 old_a = old_b = 0;
517 group_size = used_size = 0;
518 bitmap_zero(maskp, nmaskbits);
519 do {
520 at_start = 1;
521 in_range = 0;
522 in_partial_range = 0;
523 a = b = 0;
524 ndigits = totaldigits;
525
526 /* Get the next cpu# or a range of cpu#'s */
527 while (buflen) {
528 old_c = c;
529 if (is_user) {
530 if (__get_user(c, ubuf++))
531 return -EFAULT;
532 } else
533 c = *buf++;
534 buflen--;
535 if (isspace(c))
536 continue;
537
538 /* A '\0' or a ',' signal the end of a cpu# or range */
539 if (c == '\0' || c == ',')
540 break;
541 /*
542 * whitespaces between digits are not allowed,
543 * but it's ok if whitespaces are on head or tail.
544 * when old_c is whilespace,
545 * if totaldigits == ndigits, whitespace is on head.
546 * if whitespace is on tail, it should not run here.
547 * as c was ',' or '\0',
548 * the last code line has broken the current loop.
549 */
550 if ((totaldigits != ndigits) && isspace(old_c))
551 return -EINVAL;
552
553 if (c == '/') {
554 used_size = a;
555 at_start = 1;
556 in_range = 0;
557 a = b = 0;
558 continue;
559 }
560
561 if (c == ':') {
562 old_a = a;
563 old_b = b;
564 at_start = 1;
565 in_range = 0;
566 in_partial_range = 1;
567 a = b = 0;
568 continue;
569 }
570
571 if (c == '-') {
572 if (at_start || in_range)
573 return -EINVAL;
574 b = 0;
575 in_range = 1;
576 at_start = 1;
577 continue;
578 }
579
580 if (!isdigit(c))
581 return -EINVAL;
582
583 b = b * 10 + (c - '0');
584 if (!in_range)
585 a = b;
586 at_start = 0;
587 totaldigits++;
588 }
589 if (ndigits == totaldigits)
590 continue;
591 if (in_partial_range) {
592 group_size = a;
593 a = old_a;
594 b = old_b;
595 old_a = old_b = 0;
596 } else {
597 used_size = group_size = b - a + 1;
598 }
599 /* if no digit is after '-', it's wrong*/
600 if (at_start && in_range)
601 return -EINVAL;
602 if (!(a <= b) || group_size == 0 || !(used_size <= group_size))
603 return -EINVAL;
604 if (b >= nmaskbits)
605 return -ERANGE;
606 while (a <= b) {
607 off = min(b - a + 1, used_size);
608 bitmap_set(maskp, a, off);
609 a += group_size;
610 }
611 } while (buflen && c == ',');
612 return 0;
613}
614
615int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
616{
617 char *nl = strchrnul(bp, '\n');
618 int len = nl - bp;
619
620 return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
621}
622EXPORT_SYMBOL(bitmap_parselist);
623
624
625/**
626 * bitmap_parselist_user()
627 *
628 * @ubuf: pointer to user buffer containing string.
629 * @ulen: buffer size in bytes. If string is smaller than this
630 * then it must be terminated with a \0.
631 * @maskp: pointer to bitmap array that will contain result.
632 * @nmaskbits: size of bitmap, in bits.
633 *
634 * Wrapper for bitmap_parselist(), providing it with user buffer.
635 *
636 * We cannot have this as an inline function in bitmap.h because it needs
637 * linux/uaccess.h to get the access_ok() declaration and this causes
638 * cyclic dependencies.
639 */
640int bitmap_parselist_user(const char __user *ubuf,
641 unsigned int ulen, unsigned long *maskp,
642 int nmaskbits)
643{
644 if (!access_ok(ubuf, ulen))
645 return -EFAULT;
646 return __bitmap_parselist((const char __force *)ubuf,
647 ulen, 1, maskp, nmaskbits);
648}
649EXPORT_SYMBOL(bitmap_parselist_user);
650
651
652/**
653 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
654 * @buf: pointer to a bitmap
655 * @pos: a bit position in @buf (0 <= @pos < @nbits)
656 * @nbits: number of valid bit positions in @buf
657 *
658 * Map the bit at position @pos in @buf (of length @nbits) to the
659 * ordinal of which set bit it is. If it is not set or if @pos
660 * is not a valid bit position, map to -1.
661 *
662 * If for example, just bits 4 through 7 are set in @buf, then @pos
663 * values 4 through 7 will get mapped to 0 through 3, respectively,
664 * and other @pos values will get mapped to -1. When @pos value 7
665 * gets mapped to (returns) @ord value 3 in this example, that means
666 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
667 *
668 * The bit positions 0 through @bits are valid positions in @buf.
669 */
670static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits)
671{
672 if (pos >= nbits || !test_bit(pos, buf))
673 return -1;
674
675 return __bitmap_weight(buf, pos);
676}
677
678/**
679 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
680 * @buf: pointer to bitmap
681 * @ord: ordinal bit position (n-th set bit, n >= 0)
682 * @nbits: number of valid bit positions in @buf
683 *
684 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
685 * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
686 * >= weight(buf), returns @nbits.
687 *
688 * If for example, just bits 4 through 7 are set in @buf, then @ord
689 * values 0 through 3 will get mapped to 4 through 7, respectively,
690 * and all other @ord values returns @nbits. When @ord value 3
691 * gets mapped to (returns) @pos value 7 in this example, that means
692 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
693 *
694 * The bit positions 0 through @nbits-1 are valid positions in @buf.
695 */
696unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits)
697{
698 unsigned int pos;
699
700 for (pos = find_first_bit(buf, nbits);
701 pos < nbits && ord;
702 pos = find_next_bit(buf, nbits, pos + 1))
703 ord--;
704
705 return pos;
706}
707
708/**
709 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
710 * @dst: remapped result
711 * @src: subset to be remapped
712 * @old: defines domain of map
713 * @new: defines range of map
714 * @nbits: number of bits in each of these bitmaps
715 *
716 * Let @old and @new define a mapping of bit positions, such that
717 * whatever position is held by the n-th set bit in @old is mapped
718 * to the n-th set bit in @new. In the more general case, allowing
719 * for the possibility that the weight 'w' of @new is less than the
720 * weight of @old, map the position of the n-th set bit in @old to
721 * the position of the m-th set bit in @new, where m == n % w.
722 *
723 * If either of the @old and @new bitmaps are empty, or if @src and
724 * @dst point to the same location, then this routine copies @src
725 * to @dst.
726 *
727 * The positions of unset bits in @old are mapped to themselves
728 * (the identify map).
729 *
730 * Apply the above specified mapping to @src, placing the result in
731 * @dst, clearing any bits previously set in @dst.
732 *
733 * For example, lets say that @old has bits 4 through 7 set, and
734 * @new has bits 12 through 15 set. This defines the mapping of bit
735 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
736 * bit positions unchanged. So if say @src comes into this routine
737 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
738 * 13 and 15 set.
739 */
740void bitmap_remap(unsigned long *dst, const unsigned long *src,
741 const unsigned long *old, const unsigned long *new,
742 unsigned int nbits)
743{
744 unsigned int oldbit, w;
745
746 if (dst == src) /* following doesn't handle inplace remaps */
747 return;
748 bitmap_zero(dst, nbits);
749
750 w = bitmap_weight(new, nbits);
751 for_each_set_bit(oldbit, src, nbits) {
752 int n = bitmap_pos_to_ord(old, oldbit, nbits);
753
754 if (n < 0 || w == 0)
755 set_bit(oldbit, dst); /* identity map */
756 else
757 set_bit(bitmap_ord_to_pos(new, n % w, nbits), dst);
758 }
759}
760EXPORT_SYMBOL(bitmap_remap);
761
762/**
763 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
764 * @oldbit: bit position to be mapped
765 * @old: defines domain of map
766 * @new: defines range of map
767 * @bits: number of bits in each of these bitmaps
768 *
769 * Let @old and @new define a mapping of bit positions, such that
770 * whatever position is held by the n-th set bit in @old is mapped
771 * to the n-th set bit in @new. In the more general case, allowing
772 * for the possibility that the weight 'w' of @new is less than the
773 * weight of @old, map the position of the n-th set bit in @old to
774 * the position of the m-th set bit in @new, where m == n % w.
775 *
776 * The positions of unset bits in @old are mapped to themselves
777 * (the identify map).
778 *
779 * Apply the above specified mapping to bit position @oldbit, returning
780 * the new bit position.
781 *
782 * For example, lets say that @old has bits 4 through 7 set, and
783 * @new has bits 12 through 15 set. This defines the mapping of bit
784 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
785 * bit positions unchanged. So if say @oldbit is 5, then this routine
786 * returns 13.
787 */
788int bitmap_bitremap(int oldbit, const unsigned long *old,
789 const unsigned long *new, int bits)
790{
791 int w = bitmap_weight(new, bits);
792 int n = bitmap_pos_to_ord(old, oldbit, bits);
793 if (n < 0 || w == 0)
794 return oldbit;
795 else
796 return bitmap_ord_to_pos(new, n % w, bits);
797}
798EXPORT_SYMBOL(bitmap_bitremap);
799
800/**
801 * bitmap_onto - translate one bitmap relative to another
802 * @dst: resulting translated bitmap
803 * @orig: original untranslated bitmap
804 * @relmap: bitmap relative to which translated
805 * @bits: number of bits in each of these bitmaps
806 *
807 * Set the n-th bit of @dst iff there exists some m such that the
808 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
809 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
810 * (If you understood the previous sentence the first time your
811 * read it, you're overqualified for your current job.)
812 *
813 * In other words, @orig is mapped onto (surjectively) @dst,
814 * using the map { <n, m> | the n-th bit of @relmap is the
815 * m-th set bit of @relmap }.
816 *
817 * Any set bits in @orig above bit number W, where W is the
818 * weight of (number of set bits in) @relmap are mapped nowhere.
819 * In particular, if for all bits m set in @orig, m >= W, then
820 * @dst will end up empty. In situations where the possibility
821 * of such an empty result is not desired, one way to avoid it is
822 * to use the bitmap_fold() operator, below, to first fold the
823 * @orig bitmap over itself so that all its set bits x are in the
824 * range 0 <= x < W. The bitmap_fold() operator does this by
825 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
826 *
827 * Example [1] for bitmap_onto():
828 * Let's say @relmap has bits 30-39 set, and @orig has bits
829 * 1, 3, 5, 7, 9 and 11 set. Then on return from this routine,
830 * @dst will have bits 31, 33, 35, 37 and 39 set.
831 *
832 * When bit 0 is set in @orig, it means turn on the bit in
833 * @dst corresponding to whatever is the first bit (if any)
834 * that is turned on in @relmap. Since bit 0 was off in the
835 * above example, we leave off that bit (bit 30) in @dst.
836 *
837 * When bit 1 is set in @orig (as in the above example), it
838 * means turn on the bit in @dst corresponding to whatever
839 * is the second bit that is turned on in @relmap. The second
840 * bit in @relmap that was turned on in the above example was
841 * bit 31, so we turned on bit 31 in @dst.
842 *
843 * Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
844 * because they were the 4th, 6th, 8th and 10th set bits
845 * set in @relmap, and the 4th, 6th, 8th and 10th bits of
846 * @orig (i.e. bits 3, 5, 7 and 9) were also set.
847 *
848 * When bit 11 is set in @orig, it means turn on the bit in
849 * @dst corresponding to whatever is the twelfth bit that is
850 * turned on in @relmap. In the above example, there were
851 * only ten bits turned on in @relmap (30..39), so that bit
852 * 11 was set in @orig had no affect on @dst.
853 *
854 * Example [2] for bitmap_fold() + bitmap_onto():
855 * Let's say @relmap has these ten bits set::
856 *
857 * 40 41 42 43 45 48 53 61 74 95
858 *
859 * (for the curious, that's 40 plus the first ten terms of the
860 * Fibonacci sequence.)
861 *
862 * Further lets say we use the following code, invoking
863 * bitmap_fold() then bitmap_onto, as suggested above to
864 * avoid the possibility of an empty @dst result::
865 *
866 * unsigned long *tmp; // a temporary bitmap's bits
867 *
868 * bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
869 * bitmap_onto(dst, tmp, relmap, bits);
870 *
871 * Then this table shows what various values of @dst would be, for
872 * various @orig's. I list the zero-based positions of each set bit.
873 * The tmp column shows the intermediate result, as computed by
874 * using bitmap_fold() to fold the @orig bitmap modulo ten
875 * (the weight of @relmap):
876 *
877 * =============== ============== =================
878 * @orig tmp @dst
879 * 0 0 40
880 * 1 1 41
881 * 9 9 95
882 * 10 0 40 [#f1]_
883 * 1 3 5 7 1 3 5 7 41 43 48 61
884 * 0 1 2 3 4 0 1 2 3 4 40 41 42 43 45
885 * 0 9 18 27 0 9 8 7 40 61 74 95
886 * 0 10 20 30 0 40
887 * 0 11 22 33 0 1 2 3 40 41 42 43
888 * 0 12 24 36 0 2 4 6 40 42 45 53
889 * 78 102 211 1 2 8 41 42 74 [#f1]_
890 * =============== ============== =================
891 *
892 * .. [#f1]
893 *
894 * For these marked lines, if we hadn't first done bitmap_fold()
895 * into tmp, then the @dst result would have been empty.
896 *
897 * If either of @orig or @relmap is empty (no set bits), then @dst
898 * will be returned empty.
899 *
900 * If (as explained above) the only set bits in @orig are in positions
901 * m where m >= W, (where W is the weight of @relmap) then @dst will
902 * once again be returned empty.
903 *
904 * All bits in @dst not set by the above rule are cleared.
905 */
906void bitmap_onto(unsigned long *dst, const unsigned long *orig,
907 const unsigned long *relmap, unsigned int bits)
908{
909 unsigned int n, m; /* same meaning as in above comment */
910
911 if (dst == orig) /* following doesn't handle inplace mappings */
912 return;
913 bitmap_zero(dst, bits);
914
915 /*
916 * The following code is a more efficient, but less
917 * obvious, equivalent to the loop:
918 * for (m = 0; m < bitmap_weight(relmap, bits); m++) {
919 * n = bitmap_ord_to_pos(orig, m, bits);
920 * if (test_bit(m, orig))
921 * set_bit(n, dst);
922 * }
923 */
924
925 m = 0;
926 for_each_set_bit(n, relmap, bits) {
927 /* m == bitmap_pos_to_ord(relmap, n, bits) */
928 if (test_bit(m, orig))
929 set_bit(n, dst);
930 m++;
931 }
932}
933EXPORT_SYMBOL(bitmap_onto);
934
935/**
936 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
937 * @dst: resulting smaller bitmap
938 * @orig: original larger bitmap
939 * @sz: specified size
940 * @nbits: number of bits in each of these bitmaps
941 *
942 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
943 * Clear all other bits in @dst. See further the comment and
944 * Example [2] for bitmap_onto() for why and how to use this.
945 */
946void bitmap_fold(unsigned long *dst, const unsigned long *orig,
947 unsigned int sz, unsigned int nbits)
948{
949 unsigned int oldbit;
950
951 if (dst == orig) /* following doesn't handle inplace mappings */
952 return;
953 bitmap_zero(dst, nbits);
954
955 for_each_set_bit(oldbit, orig, nbits)
956 set_bit(oldbit % sz, dst);
957}
958EXPORT_SYMBOL(bitmap_fold);
959
960/*
961 * Common code for bitmap_*_region() routines.
962 * bitmap: array of unsigned longs corresponding to the bitmap
963 * pos: the beginning of the region
964 * order: region size (log base 2 of number of bits)
965 * reg_op: operation(s) to perform on that region of bitmap
966 *
967 * Can set, verify and/or release a region of bits in a bitmap,
968 * depending on which combination of REG_OP_* flag bits is set.
969 *
970 * A region of a bitmap is a sequence of bits in the bitmap, of
971 * some size '1 << order' (a power of two), aligned to that same
972 * '1 << order' power of two.
973 *
974 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
975 * Returns 0 in all other cases and reg_ops.
976 */
977
978enum {
979 REG_OP_ISFREE, /* true if region is all zero bits */
980 REG_OP_ALLOC, /* set all bits in region */
981 REG_OP_RELEASE, /* clear all bits in region */
982};
983
984static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
985{
986 int nbits_reg; /* number of bits in region */
987 int index; /* index first long of region in bitmap */
988 int offset; /* bit offset region in bitmap[index] */
989 int nlongs_reg; /* num longs spanned by region in bitmap */
990 int nbitsinlong; /* num bits of region in each spanned long */
991 unsigned long mask; /* bitmask for one long of region */
992 int i; /* scans bitmap by longs */
993 int ret = 0; /* return value */
994
995 /*
996 * Either nlongs_reg == 1 (for small orders that fit in one long)
997 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
998 */
999 nbits_reg = 1 << order;
1000 index = pos / BITS_PER_LONG;
1001 offset = pos - (index * BITS_PER_LONG);
1002 nlongs_reg = BITS_TO_LONGS(nbits_reg);
1003 nbitsinlong = min(nbits_reg, BITS_PER_LONG);
1004
1005 /*
1006 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1007 * overflows if nbitsinlong == BITS_PER_LONG.
1008 */
1009 mask = (1UL << (nbitsinlong - 1));
1010 mask += mask - 1;
1011 mask <<= offset;
1012
1013 switch (reg_op) {
1014 case REG_OP_ISFREE:
1015 for (i = 0; i < nlongs_reg; i++) {
1016 if (bitmap[index + i] & mask)
1017 goto done;
1018 }
1019 ret = 1; /* all bits in region free (zero) */
1020 break;
1021
1022 case REG_OP_ALLOC:
1023 for (i = 0; i < nlongs_reg; i++)
1024 bitmap[index + i] |= mask;
1025 break;
1026
1027 case REG_OP_RELEASE:
1028 for (i = 0; i < nlongs_reg; i++)
1029 bitmap[index + i] &= ~mask;
1030 break;
1031 }
1032done:
1033 return ret;
1034}
1035
1036/**
1037 * bitmap_find_free_region - find a contiguous aligned mem region
1038 * @bitmap: array of unsigned longs corresponding to the bitmap
1039 * @bits: number of bits in the bitmap
1040 * @order: region size (log base 2 of number of bits) to find
1041 *
1042 * Find a region of free (zero) bits in a @bitmap of @bits bits and
1043 * allocate them (set them to one). Only consider regions of length
1044 * a power (@order) of two, aligned to that power of two, which
1045 * makes the search algorithm much faster.
1046 *
1047 * Return the bit offset in bitmap of the allocated region,
1048 * or -errno on failure.
1049 */
1050int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
1051{
1052 unsigned int pos, end; /* scans bitmap by regions of size order */
1053
1054 for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
1055 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1056 continue;
1057 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1058 return pos;
1059 }
1060 return -ENOMEM;
1061}
1062EXPORT_SYMBOL(bitmap_find_free_region);
1063
1064/**
1065 * bitmap_release_region - release allocated bitmap region
1066 * @bitmap: array of unsigned longs corresponding to the bitmap
1067 * @pos: beginning of bit region to release
1068 * @order: region size (log base 2 of number of bits) to release
1069 *
1070 * This is the complement to __bitmap_find_free_region() and releases
1071 * the found region (by clearing it in the bitmap).
1072 *
1073 * No return value.
1074 */
1075void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
1076{
1077 __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1078}
1079EXPORT_SYMBOL(bitmap_release_region);
1080
1081/**
1082 * bitmap_allocate_region - allocate bitmap region
1083 * @bitmap: array of unsigned longs corresponding to the bitmap
1084 * @pos: beginning of bit region to allocate
1085 * @order: region size (log base 2 of number of bits) to allocate
1086 *
1087 * Allocate (set bits in) a specified region of a bitmap.
1088 *
1089 * Return 0 on success, or %-EBUSY if specified region wasn't
1090 * free (not all bits were zero).
1091 */
1092int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
1093{
1094 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1095 return -EBUSY;
1096 return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1097}
1098EXPORT_SYMBOL(bitmap_allocate_region);
1099
1100/**
1101 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1102 * @dst: destination buffer
1103 * @src: bitmap to copy
1104 * @nbits: number of bits in the bitmap
1105 *
1106 * Require nbits % BITS_PER_LONG == 0.
1107 */
1108#ifdef __BIG_ENDIAN
1109void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits)
1110{
1111 unsigned int i;
1112
1113 for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1114 if (BITS_PER_LONG == 64)
1115 dst[i] = cpu_to_le64(src[i]);
1116 else
1117 dst[i] = cpu_to_le32(src[i]);
1118 }
1119}
1120EXPORT_SYMBOL(bitmap_copy_le);
1121#endif
1122
1123unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags)
1124{
1125 return kmalloc_array(BITS_TO_LONGS(nbits), sizeof(unsigned long),
1126 flags);
1127}
1128EXPORT_SYMBOL(bitmap_alloc);
1129
1130unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags)
1131{
1132 return bitmap_alloc(nbits, flags | __GFP_ZERO);
1133}
1134EXPORT_SYMBOL(bitmap_zalloc);
1135
1136void bitmap_free(const unsigned long *bitmap)
1137{
1138 kfree(bitmap);
1139}
1140EXPORT_SYMBOL(bitmap_free);
1141
1142#if BITS_PER_LONG == 64
1143/**
1144 * bitmap_from_arr32 - copy the contents of u32 array of bits to bitmap
1145 * @bitmap: array of unsigned longs, the destination bitmap
1146 * @buf: array of u32 (in host byte order), the source bitmap
1147 * @nbits: number of bits in @bitmap
1148 */
1149void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf, unsigned int nbits)
1150{
1151 unsigned int i, halfwords;
1152
1153 halfwords = DIV_ROUND_UP(nbits, 32);
1154 for (i = 0; i < halfwords; i++) {
1155 bitmap[i/2] = (unsigned long) buf[i];
1156 if (++i < halfwords)
1157 bitmap[i/2] |= ((unsigned long) buf[i]) << 32;
1158 }
1159
1160 /* Clear tail bits in last word beyond nbits. */
1161 if (nbits % BITS_PER_LONG)
1162 bitmap[(halfwords - 1) / 2] &= BITMAP_LAST_WORD_MASK(nbits);
1163}
1164EXPORT_SYMBOL(bitmap_from_arr32);
1165
1166/**
1167 * bitmap_to_arr32 - copy the contents of bitmap to a u32 array of bits
1168 * @buf: array of u32 (in host byte order), the dest bitmap
1169 * @bitmap: array of unsigned longs, the source bitmap
1170 * @nbits: number of bits in @bitmap
1171 */
1172void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits)
1173{
1174 unsigned int i, halfwords;
1175
1176 halfwords = DIV_ROUND_UP(nbits, 32);
1177 for (i = 0; i < halfwords; i++) {
1178 buf[i] = (u32) (bitmap[i/2] & UINT_MAX);
1179 if (++i < halfwords)
1180 buf[i] = (u32) (bitmap[i/2] >> 32);
1181 }
1182
1183 /* Clear tail bits in last element of array beyond nbits. */
1184 if (nbits % BITS_PER_LONG)
1185 buf[halfwords - 1] &= (u32) (UINT_MAX >> ((-nbits) & 31));
1186}
1187EXPORT_SYMBOL(bitmap_to_arr32);
1188
1189#endif
1190