Version:  2.0.40 2.2.26 2.4.37 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0

Linux/lib/bitmap.c

  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 
 45 int __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 }
 58 EXPORT_SYMBOL(__bitmap_empty);
 59 
 60 int __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 }
 73 EXPORT_SYMBOL(__bitmap_full);
 74 
 75 int __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 }
 89 EXPORT_SYMBOL(__bitmap_equal);
 90 
 91 void __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 }
100 EXPORT_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  */
113 void __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 }
143 EXPORT_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 
158 void __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 }
181 EXPORT_SYMBOL(__bitmap_shift_left);
182 
183 int __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 }
197 EXPORT_SYMBOL(__bitmap_and);
198 
199 void __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 }
208 EXPORT_SYMBOL(__bitmap_or);
209 
210 void __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 }
219 EXPORT_SYMBOL(__bitmap_xor);
220 
221 int __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 }
235 EXPORT_SYMBOL(__bitmap_andnot);
236 
237 int __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 }
250 EXPORT_SYMBOL(__bitmap_intersects);
251 
252 int __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 }
265 EXPORT_SYMBOL(__bitmap_subset);
266 
267 int __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 }
280 EXPORT_SYMBOL(__bitmap_weight);
281 
282 void 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 }
301 EXPORT_SYMBOL(bitmap_set);
302 
303 void 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 }
322 EXPORT_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  */
337 unsigned 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;
345 again:
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 }
361 EXPORT_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  */
388 int __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 }
456 EXPORT_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  */
473 int 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 }
483 EXPORT_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  */
496 int 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 }
510 EXPORT_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  */
532 static 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 - '');
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 
602 int 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 }
609 EXPORT_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  */
627 int 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 }
636 EXPORT_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  */
657 static 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  */
683 unsigned 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  */
727 void 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 }
747 EXPORT_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  */
775 int 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 }
785 EXPORT_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  */
887 void 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 }
914 EXPORT_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  */
927 void 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 }
939 EXPORT_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 
959 enum {
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 
965 static 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         }
1013 done:
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  */
1031 int 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 }
1043 EXPORT_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  */
1056 void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
1057 {
1058         __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1059 }
1060 EXPORT_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  */
1073 int 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 }
1079 EXPORT_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
1090 void 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 }
1101 EXPORT_SYMBOL(bitmap_copy_le);
1102 #endif
1103 

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