projects/linux·blob v4.0-rc3 · refs

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