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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 #include <linux/kernel.h>
 16 #include <linux/string.h>
 17 
 18 #include <asm/page.h>
 19 #include <asm/uaccess.h>
 20 
 21 /*
 22  * bitmaps provide an array of bits, implemented using an an
 23  * array of unsigned longs.  The number of valid bits in a
 24  * given bitmap does _not_ need to be an exact multiple of
 25  * BITS_PER_LONG.
 26  *
 27  * The possible unused bits in the last, partially used word
 28  * of a bitmap are 'don't care'.  The implementation makes
 29  * no particular effort to keep them zero.  It ensures that
 30  * their value will not affect the results of any operation.
 31  * The bitmap operations that return Boolean (bitmap_empty,
 32  * for example) or scalar (bitmap_weight, for example) results
 33  * carefully filter out these unused bits from impacting their
 34  * results.
 35  *
 36  * These operations actually hold to a slightly stronger rule:
 37  * if you don't input any bitmaps to these ops that have some
 38  * unused bits set, then they won't output any set unused bits
 39  * in output bitmaps.
 40  *
 41  * The byte ordering of bitmaps is more natural on little
 42  * endian architectures.  See the big-endian headers
 43  * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
 44  * for the best explanations of this ordering.
 45  */
 46 
 47 int __bitmap_equal(const unsigned long *bitmap1,
 48                 const unsigned long *bitmap2, unsigned int bits)
 49 {
 50         unsigned int k, lim = bits/BITS_PER_LONG;
 51         for (k = 0; k < lim; ++k)
 52                 if (bitmap1[k] != bitmap2[k])
 53                         return 0;
 54 
 55         if (bits % BITS_PER_LONG)
 56                 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
 57                         return 0;
 58 
 59         return 1;
 60 }
 61 EXPORT_SYMBOL(__bitmap_equal);
 62 
 63 void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
 64 {
 65         unsigned int k, lim = bits/BITS_PER_LONG;
 66         for (k = 0; k < lim; ++k)
 67                 dst[k] = ~src[k];
 68 
 69         if (bits % BITS_PER_LONG)
 70                 dst[k] = ~src[k];
 71 }
 72 EXPORT_SYMBOL(__bitmap_complement);
 73 
 74 /**
 75  * __bitmap_shift_right - logical right shift of the bits in a bitmap
 76  *   @dst : destination bitmap
 77  *   @src : source bitmap
 78  *   @shift : shift by this many bits
 79  *   @nbits : bitmap size, in bits
 80  *
 81  * Shifting right (dividing) means moving bits in the MS -> LS bit
 82  * direction.  Zeros are fed into the vacated MS positions and the
 83  * LS bits shifted off the bottom are lost.
 84  */
 85 void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
 86                         unsigned shift, unsigned nbits)
 87 {
 88         unsigned k, lim = BITS_TO_LONGS(nbits);
 89         unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
 90         unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
 91         for (k = 0; off + k < lim; ++k) {
 92                 unsigned long upper, lower;
 93 
 94                 /*
 95                  * If shift is not word aligned, take lower rem bits of
 96                  * word above and make them the top rem bits of result.
 97                  */
 98                 if (!rem || off + k + 1 >= lim)
 99                         upper = 0;
100                 else {
101                         upper = src[off + k + 1];
102                         if (off + k + 1 == lim - 1)
103                                 upper &= mask;
104                         upper <<= (BITS_PER_LONG - rem);
105                 }
106                 lower = src[off + k];
107                 if (off + k == lim - 1)
108                         lower &= mask;
109                 lower >>= rem;
110                 dst[k] = lower | upper;
111         }
112         if (off)
113                 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
114 }
115 EXPORT_SYMBOL(__bitmap_shift_right);
116 
117 
118 /**
119  * __bitmap_shift_left - logical left shift of the bits in a bitmap
120  *   @dst : destination bitmap
121  *   @src : source bitmap
122  *   @shift : shift by this many bits
123  *   @nbits : bitmap size, in bits
124  *
125  * Shifting left (multiplying) means moving bits in the LS -> MS
126  * direction.  Zeros are fed into the vacated LS bit positions
127  * and those MS bits shifted off the top are lost.
128  */
129 
130 void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
131                         unsigned int shift, unsigned int nbits)
132 {
133         int k;
134         unsigned int lim = BITS_TO_LONGS(nbits);
135         unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
136         for (k = lim - off - 1; k >= 0; --k) {
137                 unsigned long upper, lower;
138 
139                 /*
140                  * If shift is not word aligned, take upper rem bits of
141                  * word below and make them the bottom rem bits of result.
142                  */
143                 if (rem && k > 0)
144                         lower = src[k - 1] >> (BITS_PER_LONG - rem);
145                 else
146                         lower = 0;
147                 upper = src[k] << rem;
148                 dst[k + off] = lower | upper;
149         }
150         if (off)
151                 memset(dst, 0, off*sizeof(unsigned long));
152 }
153 EXPORT_SYMBOL(__bitmap_shift_left);
154 
155 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
156                                 const unsigned long *bitmap2, unsigned int bits)
157 {
158         unsigned int k;
159         unsigned int lim = bits/BITS_PER_LONG;
160         unsigned long result = 0;
161 
162         for (k = 0; k < lim; k++)
163                 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
164         if (bits % BITS_PER_LONG)
165                 result |= (dst[k] = bitmap1[k] & bitmap2[k] &
166                            BITMAP_LAST_WORD_MASK(bits));
167         return result != 0;
168 }
169 EXPORT_SYMBOL(__bitmap_and);
170 
171 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
172                                 const unsigned long *bitmap2, unsigned int bits)
173 {
174         unsigned int k;
175         unsigned int nr = BITS_TO_LONGS(bits);
176 
177         for (k = 0; k < nr; k++)
178                 dst[k] = bitmap1[k] | bitmap2[k];
179 }
180 EXPORT_SYMBOL(__bitmap_or);
181 
182 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
183                                 const unsigned long *bitmap2, unsigned int bits)
184 {
185         unsigned int k;
186         unsigned int nr = BITS_TO_LONGS(bits);
187 
188         for (k = 0; k < nr; k++)
189                 dst[k] = bitmap1[k] ^ bitmap2[k];
190 }
191 EXPORT_SYMBOL(__bitmap_xor);
192 
193 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
194                                 const unsigned long *bitmap2, unsigned int bits)
195 {
196         unsigned int k;
197         unsigned int lim = bits/BITS_PER_LONG;
198         unsigned long result = 0;
199 
200         for (k = 0; k < lim; k++)
201                 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
202         if (bits % BITS_PER_LONG)
203                 result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
204                            BITMAP_LAST_WORD_MASK(bits));
205         return result != 0;
206 }
207 EXPORT_SYMBOL(__bitmap_andnot);
208 
209 int __bitmap_intersects(const unsigned long *bitmap1,
210                         const unsigned long *bitmap2, unsigned int bits)
211 {
212         unsigned int k, lim = bits/BITS_PER_LONG;
213         for (k = 0; k < lim; ++k)
214                 if (bitmap1[k] & bitmap2[k])
215                         return 1;
216 
217         if (bits % BITS_PER_LONG)
218                 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
219                         return 1;
220         return 0;
221 }
222 EXPORT_SYMBOL(__bitmap_intersects);
223 
224 int __bitmap_subset(const unsigned long *bitmap1,
225                     const unsigned long *bitmap2, unsigned int bits)
226 {
227         unsigned int k, lim = bits/BITS_PER_LONG;
228         for (k = 0; k < lim; ++k)
229                 if (bitmap1[k] & ~bitmap2[k])
230                         return 0;
231 
232         if (bits % BITS_PER_LONG)
233                 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
234                         return 0;
235         return 1;
236 }
237 EXPORT_SYMBOL(__bitmap_subset);
238 
239 int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
240 {
241         unsigned int k, lim = bits/BITS_PER_LONG;
242         int w = 0;
243 
244         for (k = 0; k < lim; k++)
245                 w += hweight_long(bitmap[k]);
246 
247         if (bits % BITS_PER_LONG)
248                 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
249 
250         return w;
251 }
252 EXPORT_SYMBOL(__bitmap_weight);
253 
254 void bitmap_set(unsigned long *map, unsigned int start, int len)
255 {
256         unsigned long *p = map + BIT_WORD(start);
257         const unsigned int size = start + len;
258         int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
259         unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
260 
261         while (len - bits_to_set >= 0) {
262                 *p |= mask_to_set;
263                 len -= bits_to_set;
264                 bits_to_set = BITS_PER_LONG;
265                 mask_to_set = ~0UL;
266                 p++;
267         }
268         if (len) {
269                 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
270                 *p |= mask_to_set;
271         }
272 }
273 EXPORT_SYMBOL(bitmap_set);
274 
275 void bitmap_clear(unsigned long *map, unsigned int start, int len)
276 {
277         unsigned long *p = map + BIT_WORD(start);
278         const unsigned int size = start + len;
279         int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
280         unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
281 
282         while (len - bits_to_clear >= 0) {
283                 *p &= ~mask_to_clear;
284                 len -= bits_to_clear;
285                 bits_to_clear = BITS_PER_LONG;
286                 mask_to_clear = ~0UL;
287                 p++;
288         }
289         if (len) {
290                 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
291                 *p &= ~mask_to_clear;
292         }
293 }
294 EXPORT_SYMBOL(bitmap_clear);
295 
296 /**
297  * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
298  * @map: The address to base the search on
299  * @size: The bitmap size in bits
300  * @start: The bitnumber to start searching at
301  * @nr: The number of zeroed bits we're looking for
302  * @align_mask: Alignment mask for zero area
303  * @align_offset: Alignment offset for zero area.
304  *
305  * The @align_mask should be one less than a power of 2; the effect is that
306  * the bit offset of all zero areas this function finds plus @align_offset
307  * is multiple of that power of 2.
308  */
309 unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
310                                              unsigned long size,
311                                              unsigned long start,
312                                              unsigned int nr,
313                                              unsigned long align_mask,
314                                              unsigned long align_offset)
315 {
316         unsigned long index, end, i;
317 again:
318         index = find_next_zero_bit(map, size, start);
319 
320         /* Align allocation */
321         index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
322 
323         end = index + nr;
324         if (end > size)
325                 return end;
326         i = find_next_bit(map, end, index);
327         if (i < end) {
328                 start = i + 1;
329                 goto again;
330         }
331         return index;
332 }
333 EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
334 
335 /*
336  * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
337  * second version by Paul Jackson, third by Joe Korty.
338  */
339 
340 #define CHUNKSZ                         32
341 #define nbits_to_hold_value(val)        fls(val)
342 #define BASEDEC 10              /* fancier cpuset lists input in decimal */
343 
344 /**
345  * __bitmap_parse - convert an ASCII hex string into a bitmap.
346  * @buf: pointer to buffer containing string.
347  * @buflen: buffer size in bytes.  If string is smaller than this
348  *    then it must be terminated with a \0.
349  * @is_user: location of buffer, 0 indicates kernel space
350  * @maskp: pointer to bitmap array that will contain result.
351  * @nmaskbits: size of bitmap, in bits.
352  *
353  * Commas group hex digits into chunks.  Each chunk defines exactly 32
354  * bits of the resultant bitmask.  No chunk may specify a value larger
355  * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
356  * then leading 0-bits are prepended.  %-EINVAL is returned for illegal
357  * characters and for grouping errors such as "1,,5", ",44", "," and "".
358  * Leading and trailing whitespace accepted, but not embedded whitespace.
359  */
360 int __bitmap_parse(const char *buf, unsigned int buflen,
361                 int is_user, unsigned long *maskp,
362                 int nmaskbits)
363 {
364         int c, old_c, totaldigits, ndigits, nchunks, nbits;
365         u32 chunk;
366         const char __user __force *ubuf = (const char __user __force *)buf;
367 
368         bitmap_zero(maskp, nmaskbits);
369 
370         nchunks = nbits = totaldigits = c = 0;
371         do {
372                 chunk = 0;
373                 ndigits = totaldigits;
374 
375                 /* Get the next chunk of the bitmap */
376                 while (buflen) {
377                         old_c = c;
378                         if (is_user) {
379                                 if (__get_user(c, ubuf++))
380                                         return -EFAULT;
381                         }
382                         else
383                                 c = *buf++;
384                         buflen--;
385                         if (isspace(c))
386                                 continue;
387 
388                         /*
389                          * If the last character was a space and the current
390                          * character isn't '\0', we've got embedded whitespace.
391                          * This is a no-no, so throw an error.
392                          */
393                         if (totaldigits && c && isspace(old_c))
394                                 return -EINVAL;
395 
396                         /* A '\0' or a ',' signal the end of the chunk */
397                         if (c == '\0' || c == ',')
398                                 break;
399 
400                         if (!isxdigit(c))
401                                 return -EINVAL;
402 
403                         /*
404                          * Make sure there are at least 4 free bits in 'chunk'.
405                          * If not, this hexdigit will overflow 'chunk', so
406                          * throw an error.
407                          */
408                         if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
409                                 return -EOVERFLOW;
410 
411                         chunk = (chunk << 4) | hex_to_bin(c);
412                         totaldigits++;
413                 }
414                 if (ndigits == totaldigits)
415                         return -EINVAL;
416                 if (nchunks == 0 && chunk == 0)
417                         continue;
418 
419                 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
420                 *maskp |= chunk;
421                 nchunks++;
422                 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
423                 if (nbits > nmaskbits)
424                         return -EOVERFLOW;
425         } while (buflen && c == ',');
426 
427         return 0;
428 }
429 EXPORT_SYMBOL(__bitmap_parse);
430 
431 /**
432  * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
433  *
434  * @ubuf: pointer to user buffer containing string.
435  * @ulen: buffer size in bytes.  If string is smaller than this
436  *    then it must be terminated with a \0.
437  * @maskp: pointer to bitmap array that will contain result.
438  * @nmaskbits: size of bitmap, in bits.
439  *
440  * Wrapper for __bitmap_parse(), providing it with user buffer.
441  *
442  * We cannot have this as an inline function in bitmap.h because it needs
443  * linux/uaccess.h to get the access_ok() declaration and this causes
444  * cyclic dependencies.
445  */
446 int bitmap_parse_user(const char __user *ubuf,
447                         unsigned int ulen, unsigned long *maskp,
448                         int nmaskbits)
449 {
450         if (!access_ok(VERIFY_READ, ubuf, ulen))
451                 return -EFAULT;
452         return __bitmap_parse((const char __force *)ubuf,
453                                 ulen, 1, maskp, nmaskbits);
454 
455 }
456 EXPORT_SYMBOL(bitmap_parse_user);
457 
458 /**
459  * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
460  * @list: indicates whether the bitmap must be list
461  * @buf: page aligned buffer into which string is placed
462  * @maskp: pointer to bitmap to convert
463  * @nmaskbits: size of bitmap, in bits
464  *
465  * Output format is a comma-separated list of decimal numbers and
466  * ranges if list is specified or hex digits grouped into comma-separated
467  * sets of 8 digits/set. Returns the number of characters written to buf.
468  *
469  * It is assumed that @buf is a pointer into a PAGE_SIZE area and that
470  * sufficient storage remains at @buf to accommodate the
471  * bitmap_print_to_pagebuf() output.
472  */
473 int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
474                             int nmaskbits)
475 {
476         ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf;
477         int n = 0;
478 
479         if (len > 1)
480                 n = list ? scnprintf(buf, len, "%*pbl\n", nmaskbits, maskp) :
481                            scnprintf(buf, len, "%*pb\n", nmaskbits, maskp);
482         return n;
483 }
484 EXPORT_SYMBOL(bitmap_print_to_pagebuf);
485 
486 /**
487  * __bitmap_parselist - convert list format ASCII string to bitmap
488  * @buf: read nul-terminated user string from this buffer
489  * @buflen: buffer size in bytes.  If string is smaller than this
490  *    then it must be terminated with a \0.
491  * @is_user: location of buffer, 0 indicates kernel space
492  * @maskp: write resulting mask here
493  * @nmaskbits: number of bits in mask to be written
494  *
495  * Input format is a comma-separated list of decimal numbers and
496  * ranges.  Consecutively set bits are shown as two hyphen-separated
497  * decimal numbers, the smallest and largest bit numbers set in
498  * the range.
499  *
500  * Returns 0 on success, -errno on invalid input strings.
501  * Error values:
502  *    %-EINVAL: second number in range smaller than first
503  *    %-EINVAL: invalid character in string
504  *    %-ERANGE: bit number specified too large for mask
505  */
506 static int __bitmap_parselist(const char *buf, unsigned int buflen,
507                 int is_user, unsigned long *maskp,
508                 int nmaskbits)
509 {
510         unsigned a, b;
511         int c, old_c, totaldigits, ndigits;
512         const char __user __force *ubuf = (const char __user __force *)buf;
513         int at_start, in_range;
514 
515         totaldigits = c = 0;
516         bitmap_zero(maskp, nmaskbits);
517         do {
518                 at_start = 1;
519                 in_range = 0;
520                 a = b = 0;
521                 ndigits = totaldigits;
522 
523                 /* Get the next cpu# or a range of cpu#'s */
524                 while (buflen) {
525                         old_c = c;
526                         if (is_user) {
527                                 if (__get_user(c, ubuf++))
528                                         return -EFAULT;
529                         } else
530                                 c = *buf++;
531                         buflen--;
532                         if (isspace(c))
533                                 continue;
534 
535                         /* A '\0' or a ',' signal the end of a cpu# or range */
536                         if (c == '\0' || c == ',')
537                                 break;
538                         /*
539                         * whitespaces between digits are not allowed,
540                         * but it's ok if whitespaces are on head or tail.
541                         * when old_c is whilespace,
542                         * if totaldigits == ndigits, whitespace is on head.
543                         * if whitespace is on tail, it should not run here.
544                         * as c was ',' or '\0',
545                         * the last code line has broken the current loop.
546                         */
547                         if ((totaldigits != ndigits) && isspace(old_c))
548                                 return -EINVAL;
549 
550                         if (c == '-') {
551                                 if (at_start || in_range)
552                                         return -EINVAL;
553                                 b = 0;
554                                 in_range = 1;
555                                 at_start = 1;
556                                 continue;
557                         }
558 
559                         if (!isdigit(c))
560                                 return -EINVAL;
561 
562                         b = b * 10 + (c - '');
563                         if (!in_range)
564                                 a = b;
565                         at_start = 0;
566                         totaldigits++;
567                 }
568                 if (ndigits == totaldigits)
569                         continue;
570                 /* if no digit is after '-', it's wrong*/
571                 if (at_start && in_range)
572                         return -EINVAL;
573                 if (!(a <= b))
574                         return -EINVAL;
575                 if (b >= nmaskbits)
576                         return -ERANGE;
577                 while (a <= b) {
578                         set_bit(a, maskp);
579                         a++;
580                 }
581         } while (buflen && c == ',');
582         return 0;
583 }
584 
585 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
586 {
587         char *nl  = strchrnul(bp, '\n');
588         int len = nl - bp;
589 
590         return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
591 }
592 EXPORT_SYMBOL(bitmap_parselist);
593 
594 
595 /**
596  * bitmap_parselist_user()
597  *
598  * @ubuf: pointer to user buffer containing string.
599  * @ulen: buffer size in bytes.  If string is smaller than this
600  *    then it must be terminated with a \0.
601  * @maskp: pointer to bitmap array that will contain result.
602  * @nmaskbits: size of bitmap, in bits.
603  *
604  * Wrapper for bitmap_parselist(), providing it with user buffer.
605  *
606  * We cannot have this as an inline function in bitmap.h because it needs
607  * linux/uaccess.h to get the access_ok() declaration and this causes
608  * cyclic dependencies.
609  */
610 int bitmap_parselist_user(const char __user *ubuf,
611                         unsigned int ulen, unsigned long *maskp,
612                         int nmaskbits)
613 {
614         if (!access_ok(VERIFY_READ, ubuf, ulen))
615                 return -EFAULT;
616         return __bitmap_parselist((const char __force *)ubuf,
617                                         ulen, 1, maskp, nmaskbits);
618 }
619 EXPORT_SYMBOL(bitmap_parselist_user);
620 
621 
622 /**
623  * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
624  *      @buf: pointer to a bitmap
625  *      @pos: a bit position in @buf (0 <= @pos < @nbits)
626  *      @nbits: number of valid bit positions in @buf
627  *
628  * Map the bit at position @pos in @buf (of length @nbits) to the
629  * ordinal of which set bit it is.  If it is not set or if @pos
630  * is not a valid bit position, map to -1.
631  *
632  * If for example, just bits 4 through 7 are set in @buf, then @pos
633  * values 4 through 7 will get mapped to 0 through 3, respectively,
634  * and other @pos values will get mapped to -1.  When @pos value 7
635  * gets mapped to (returns) @ord value 3 in this example, that means
636  * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
637  *
638  * The bit positions 0 through @bits are valid positions in @buf.
639  */
640 static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits)
641 {
642         if (pos >= nbits || !test_bit(pos, buf))
643                 return -1;
644 
645         return __bitmap_weight(buf, pos);
646 }
647 
648 /**
649  * bitmap_ord_to_pos - find position of n-th set bit in bitmap
650  *      @buf: pointer to bitmap
651  *      @ord: ordinal bit position (n-th set bit, n >= 0)
652  *      @nbits: number of valid bit positions in @buf
653  *
654  * Map the ordinal offset of bit @ord in @buf to its position in @buf.
655  * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
656  * >= weight(buf), returns @nbits.
657  *
658  * If for example, just bits 4 through 7 are set in @buf, then @ord
659  * values 0 through 3 will get mapped to 4 through 7, respectively,
660  * and all other @ord values returns @nbits.  When @ord value 3
661  * gets mapped to (returns) @pos value 7 in this example, that means
662  * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
663  *
664  * The bit positions 0 through @nbits-1 are valid positions in @buf.
665  */
666 unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits)
667 {
668         unsigned int pos;
669 
670         for (pos = find_first_bit(buf, nbits);
671              pos < nbits && ord;
672              pos = find_next_bit(buf, nbits, pos + 1))
673                 ord--;
674 
675         return pos;
676 }
677 
678 /**
679  * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
680  *      @dst: remapped result
681  *      @src: subset to be remapped
682  *      @old: defines domain of map
683  *      @new: defines range of map
684  *      @nbits: number of bits in each of these bitmaps
685  *
686  * Let @old and @new define a mapping of bit positions, such that
687  * whatever position is held by the n-th set bit in @old is mapped
688  * to the n-th set bit in @new.  In the more general case, allowing
689  * for the possibility that the weight 'w' of @new is less than the
690  * weight of @old, map the position of the n-th set bit in @old to
691  * the position of the m-th set bit in @new, where m == n % w.
692  *
693  * If either of the @old and @new bitmaps are empty, or if @src and
694  * @dst point to the same location, then this routine copies @src
695  * to @dst.
696  *
697  * The positions of unset bits in @old are mapped to themselves
698  * (the identify map).
699  *
700  * Apply the above specified mapping to @src, placing the result in
701  * @dst, clearing any bits previously set in @dst.
702  *
703  * For example, lets say that @old has bits 4 through 7 set, and
704  * @new has bits 12 through 15 set.  This defines the mapping of bit
705  * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
706  * bit positions unchanged.  So if say @src comes into this routine
707  * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
708  * 13 and 15 set.
709  */
710 void bitmap_remap(unsigned long *dst, const unsigned long *src,
711                 const unsigned long *old, const unsigned long *new,
712                 unsigned int nbits)
713 {
714         unsigned int oldbit, w;
715 
716         if (dst == src)         /* following doesn't handle inplace remaps */
717                 return;
718         bitmap_zero(dst, nbits);
719 
720         w = bitmap_weight(new, nbits);
721         for_each_set_bit(oldbit, src, nbits) {
722                 int n = bitmap_pos_to_ord(old, oldbit, nbits);
723 
724                 if (n < 0 || w == 0)
725                         set_bit(oldbit, dst);   /* identity map */
726                 else
727                         set_bit(bitmap_ord_to_pos(new, n % w, nbits), dst);
728         }
729 }
730 EXPORT_SYMBOL(bitmap_remap);
731 
732 /**
733  * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
734  *      @oldbit: bit position to be mapped
735  *      @old: defines domain of map
736  *      @new: defines range of map
737  *      @bits: number of bits in each of these bitmaps
738  *
739  * Let @old and @new define a mapping of bit positions, such that
740  * whatever position is held by the n-th set bit in @old is mapped
741  * to the n-th set bit in @new.  In the more general case, allowing
742  * for the possibility that the weight 'w' of @new is less than the
743  * weight of @old, map the position of the n-th set bit in @old to
744  * the position of the m-th set bit in @new, where m == n % w.
745  *
746  * The positions of unset bits in @old are mapped to themselves
747  * (the identify map).
748  *
749  * Apply the above specified mapping to bit position @oldbit, returning
750  * the new bit position.
751  *
752  * For example, lets say that @old has bits 4 through 7 set, and
753  * @new has bits 12 through 15 set.  This defines the mapping of bit
754  * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
755  * bit positions unchanged.  So if say @oldbit is 5, then this routine
756  * returns 13.
757  */
758 int bitmap_bitremap(int oldbit, const unsigned long *old,
759                                 const unsigned long *new, int bits)
760 {
761         int w = bitmap_weight(new, bits);
762         int n = bitmap_pos_to_ord(old, oldbit, bits);
763         if (n < 0 || w == 0)
764                 return oldbit;
765         else
766                 return bitmap_ord_to_pos(new, n % w, bits);
767 }
768 EXPORT_SYMBOL(bitmap_bitremap);
769 
770 /**
771  * bitmap_onto - translate one bitmap relative to another
772  *      @dst: resulting translated bitmap
773  *      @orig: original untranslated bitmap
774  *      @relmap: bitmap relative to which translated
775  *      @bits: number of bits in each of these bitmaps
776  *
777  * Set the n-th bit of @dst iff there exists some m such that the
778  * n-th bit of @relmap is set, the m-th bit of @orig is set, and
779  * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
780  * (If you understood the previous sentence the first time your
781  * read it, you're overqualified for your current job.)
782  *
783  * In other words, @orig is mapped onto (surjectively) @dst,
784  * using the map { <n, m> | the n-th bit of @relmap is the
785  * m-th set bit of @relmap }.
786  *
787  * Any set bits in @orig above bit number W, where W is the
788  * weight of (number of set bits in) @relmap are mapped nowhere.
789  * In particular, if for all bits m set in @orig, m >= W, then
790  * @dst will end up empty.  In situations where the possibility
791  * of such an empty result is not desired, one way to avoid it is
792  * to use the bitmap_fold() operator, below, to first fold the
793  * @orig bitmap over itself so that all its set bits x are in the
794  * range 0 <= x < W.  The bitmap_fold() operator does this by
795  * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
796  *
797  * Example [1] for bitmap_onto():
798  *  Let's say @relmap has bits 30-39 set, and @orig has bits
799  *  1, 3, 5, 7, 9 and 11 set.  Then on return from this routine,
800  *  @dst will have bits 31, 33, 35, 37 and 39 set.
801  *
802  *  When bit 0 is set in @orig, it means turn on the bit in
803  *  @dst corresponding to whatever is the first bit (if any)
804  *  that is turned on in @relmap.  Since bit 0 was off in the
805  *  above example, we leave off that bit (bit 30) in @dst.
806  *
807  *  When bit 1 is set in @orig (as in the above example), it
808  *  means turn on the bit in @dst corresponding to whatever
809  *  is the second bit that is turned on in @relmap.  The second
810  *  bit in @relmap that was turned on in the above example was
811  *  bit 31, so we turned on bit 31 in @dst.
812  *
813  *  Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
814  *  because they were the 4th, 6th, 8th and 10th set bits
815  *  set in @relmap, and the 4th, 6th, 8th and 10th bits of
816  *  @orig (i.e. bits 3, 5, 7 and 9) were also set.
817  *
818  *  When bit 11 is set in @orig, it means turn on the bit in
819  *  @dst corresponding to whatever is the twelfth bit that is
820  *  turned on in @relmap.  In the above example, there were
821  *  only ten bits turned on in @relmap (30..39), so that bit
822  *  11 was set in @orig had no affect on @dst.
823  *
824  * Example [2] for bitmap_fold() + bitmap_onto():
825  *  Let's say @relmap has these ten bits set:
826  *              40 41 42 43 45 48 53 61 74 95
827  *  (for the curious, that's 40 plus the first ten terms of the
828  *  Fibonacci sequence.)
829  *
830  *  Further lets say we use the following code, invoking
831  *  bitmap_fold() then bitmap_onto, as suggested above to
832  *  avoid the possibility of an empty @dst result:
833  *
834  *      unsigned long *tmp;     // a temporary bitmap's bits
835  *
836  *      bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
837  *      bitmap_onto(dst, tmp, relmap, bits);
838  *
839  *  Then this table shows what various values of @dst would be, for
840  *  various @orig's.  I list the zero-based positions of each set bit.
841  *  The tmp column shows the intermediate result, as computed by
842  *  using bitmap_fold() to fold the @orig bitmap modulo ten
843  *  (the weight of @relmap).
844  *
845  *      @orig           tmp            @dst
846  *      0                0             40
847  *      1                1             41
848  *      9                9             95
849  *      10               0             40 (*)
850  *      1 3 5 7          1 3 5 7       41 43 48 61
851  *      0 1 2 3 4        0 1 2 3 4     40 41 42 43 45
852  *      0 9 18 27        0 9 8 7       40 61 74 95
853  *      0 10 20 30       0             40
854  *      0 11 22 33       0 1 2 3       40 41 42 43
855  *      0 12 24 36       0 2 4 6       40 42 45 53
856  *      78 102 211       1 2 8         41 42 74 (*)
857  *
858  * (*) For these marked lines, if we hadn't first done bitmap_fold()
859  *     into tmp, then the @dst result would have been empty.
860  *
861  * If either of @orig or @relmap is empty (no set bits), then @dst
862  * will be returned empty.
863  *
864  * If (as explained above) the only set bits in @orig are in positions
865  * m where m >= W, (where W is the weight of @relmap) then @dst will
866  * once again be returned empty.
867  *
868  * All bits in @dst not set by the above rule are cleared.
869  */
870 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
871                         const unsigned long *relmap, unsigned int bits)
872 {
873         unsigned int n, m;      /* same meaning as in above comment */
874 
875         if (dst == orig)        /* following doesn't handle inplace mappings */
876                 return;
877         bitmap_zero(dst, bits);
878 
879         /*
880          * The following code is a more efficient, but less
881          * obvious, equivalent to the loop:
882          *      for (m = 0; m < bitmap_weight(relmap, bits); m++) {
883          *              n = bitmap_ord_to_pos(orig, m, bits);
884          *              if (test_bit(m, orig))
885          *                      set_bit(n, dst);
886          *      }
887          */
888 
889         m = 0;
890         for_each_set_bit(n, relmap, bits) {
891                 /* m == bitmap_pos_to_ord(relmap, n, bits) */
892                 if (test_bit(m, orig))
893                         set_bit(n, dst);
894                 m++;
895         }
896 }
897 EXPORT_SYMBOL(bitmap_onto);
898 
899 /**
900  * bitmap_fold - fold larger bitmap into smaller, modulo specified size
901  *      @dst: resulting smaller bitmap
902  *      @orig: original larger bitmap
903  *      @sz: specified size
904  *      @nbits: number of bits in each of these bitmaps
905  *
906  * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
907  * Clear all other bits in @dst.  See further the comment and
908  * Example [2] for bitmap_onto() for why and how to use this.
909  */
910 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
911                         unsigned int sz, unsigned int nbits)
912 {
913         unsigned int oldbit;
914 
915         if (dst == orig)        /* following doesn't handle inplace mappings */
916                 return;
917         bitmap_zero(dst, nbits);
918 
919         for_each_set_bit(oldbit, orig, nbits)
920                 set_bit(oldbit % sz, dst);
921 }
922 EXPORT_SYMBOL(bitmap_fold);
923 
924 /*
925  * Common code for bitmap_*_region() routines.
926  *      bitmap: array of unsigned longs corresponding to the bitmap
927  *      pos: the beginning of the region
928  *      order: region size (log base 2 of number of bits)
929  *      reg_op: operation(s) to perform on that region of bitmap
930  *
931  * Can set, verify and/or release a region of bits in a bitmap,
932  * depending on which combination of REG_OP_* flag bits is set.
933  *
934  * A region of a bitmap is a sequence of bits in the bitmap, of
935  * some size '1 << order' (a power of two), aligned to that same
936  * '1 << order' power of two.
937  *
938  * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
939  * Returns 0 in all other cases and reg_ops.
940  */
941 
942 enum {
943         REG_OP_ISFREE,          /* true if region is all zero bits */
944         REG_OP_ALLOC,           /* set all bits in region */
945         REG_OP_RELEASE,         /* clear all bits in region */
946 };
947 
948 static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
949 {
950         int nbits_reg;          /* number of bits in region */
951         int index;              /* index first long of region in bitmap */
952         int offset;             /* bit offset region in bitmap[index] */
953         int nlongs_reg;         /* num longs spanned by region in bitmap */
954         int nbitsinlong;        /* num bits of region in each spanned long */
955         unsigned long mask;     /* bitmask for one long of region */
956         int i;                  /* scans bitmap by longs */
957         int ret = 0;            /* return value */
958 
959         /*
960          * Either nlongs_reg == 1 (for small orders that fit in one long)
961          * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
962          */
963         nbits_reg = 1 << order;
964         index = pos / BITS_PER_LONG;
965         offset = pos - (index * BITS_PER_LONG);
966         nlongs_reg = BITS_TO_LONGS(nbits_reg);
967         nbitsinlong = min(nbits_reg,  BITS_PER_LONG);
968 
969         /*
970          * Can't do "mask = (1UL << nbitsinlong) - 1", as that
971          * overflows if nbitsinlong == BITS_PER_LONG.
972          */
973         mask = (1UL << (nbitsinlong - 1));
974         mask += mask - 1;
975         mask <<= offset;
976 
977         switch (reg_op) {
978         case REG_OP_ISFREE:
979                 for (i = 0; i < nlongs_reg; i++) {
980                         if (bitmap[index + i] & mask)
981                                 goto done;
982                 }
983                 ret = 1;        /* all bits in region free (zero) */
984                 break;
985 
986         case REG_OP_ALLOC:
987                 for (i = 0; i < nlongs_reg; i++)
988                         bitmap[index + i] |= mask;
989                 break;
990 
991         case REG_OP_RELEASE:
992                 for (i = 0; i < nlongs_reg; i++)
993                         bitmap[index + i] &= ~mask;
994                 break;
995         }
996 done:
997         return ret;
998 }
999 
1000 /**
1001  * bitmap_find_free_region - find a contiguous aligned mem region
1002  *      @bitmap: array of unsigned longs corresponding to the bitmap
1003  *      @bits: number of bits in the bitmap
1004  *      @order: region size (log base 2 of number of bits) to find
1005  *
1006  * Find a region of free (zero) bits in a @bitmap of @bits bits and
1007  * allocate them (set them to one).  Only consider regions of length
1008  * a power (@order) of two, aligned to that power of two, which
1009  * makes the search algorithm much faster.
1010  *
1011  * Return the bit offset in bitmap of the allocated region,
1012  * or -errno on failure.
1013  */
1014 int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
1015 {
1016         unsigned int pos, end;          /* scans bitmap by regions of size order */
1017 
1018         for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
1019                 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1020                         continue;
1021                 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1022                 return pos;
1023         }
1024         return -ENOMEM;
1025 }
1026 EXPORT_SYMBOL(bitmap_find_free_region);
1027 
1028 /**
1029  * bitmap_release_region - release allocated bitmap region
1030  *      @bitmap: array of unsigned longs corresponding to the bitmap
1031  *      @pos: beginning of bit region to release
1032  *      @order: region size (log base 2 of number of bits) to release
1033  *
1034  * This is the complement to __bitmap_find_free_region() and releases
1035  * the found region (by clearing it in the bitmap).
1036  *
1037  * No return value.
1038  */
1039 void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
1040 {
1041         __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1042 }
1043 EXPORT_SYMBOL(bitmap_release_region);
1044 
1045 /**
1046  * bitmap_allocate_region - allocate bitmap region
1047  *      @bitmap: array of unsigned longs corresponding to the bitmap
1048  *      @pos: beginning of bit region to allocate
1049  *      @order: region size (log base 2 of number of bits) to allocate
1050  *
1051  * Allocate (set bits in) a specified region of a bitmap.
1052  *
1053  * Return 0 on success, or %-EBUSY if specified region wasn't
1054  * free (not all bits were zero).
1055  */
1056 int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
1057 {
1058         if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1059                 return -EBUSY;
1060         return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1061 }
1062 EXPORT_SYMBOL(bitmap_allocate_region);
1063 
1064 /**
1065  * bitmap_from_u32array - copy the contents of a u32 array of bits to bitmap
1066  *      @bitmap: array of unsigned longs, the destination bitmap, non NULL
1067  *      @nbits: number of bits in @bitmap
1068  *      @buf: array of u32 (in host byte order), the source bitmap, non NULL
1069  *      @nwords: number of u32 words in @buf
1070  *
1071  * copy min(nbits, 32*nwords) bits from @buf to @bitmap, remaining
1072  * bits between nword and nbits in @bitmap (if any) are cleared. In
1073  * last word of @bitmap, the bits beyond nbits (if any) are kept
1074  * unchanged.
1075  *
1076  * Return the number of bits effectively copied.
1077  */
1078 unsigned int
1079 bitmap_from_u32array(unsigned long *bitmap, unsigned int nbits,
1080                      const u32 *buf, unsigned int nwords)
1081 {
1082         unsigned int dst_idx, src_idx;
1083 
1084         for (src_idx = dst_idx = 0; dst_idx < BITS_TO_LONGS(nbits); ++dst_idx) {
1085                 unsigned long part = 0;
1086 
1087                 if (src_idx < nwords)
1088                         part = buf[src_idx++];
1089 
1090 #if BITS_PER_LONG == 64
1091                 if (src_idx < nwords)
1092                         part |= ((unsigned long) buf[src_idx++]) << 32;
1093 #endif
1094 
1095                 if (dst_idx < nbits/BITS_PER_LONG)
1096                         bitmap[dst_idx] = part;
1097                 else {
1098                         unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
1099 
1100                         bitmap[dst_idx] = (bitmap[dst_idx] & ~mask)
1101                                 | (part & mask);
1102                 }
1103         }
1104 
1105         return min_t(unsigned int, nbits, 32*nwords);
1106 }
1107 EXPORT_SYMBOL(bitmap_from_u32array);
1108 
1109 /**
1110  * bitmap_to_u32array - copy the contents of bitmap to a u32 array of bits
1111  *      @buf: array of u32 (in host byte order), the dest bitmap, non NULL
1112  *      @nwords: number of u32 words in @buf
1113  *      @bitmap: array of unsigned longs, the source bitmap, non NULL
1114  *      @nbits: number of bits in @bitmap
1115  *
1116  * copy min(nbits, 32*nwords) bits from @bitmap to @buf. Remaining
1117  * bits after nbits in @buf (if any) are cleared.
1118  *
1119  * Return the number of bits effectively copied.
1120  */
1121 unsigned int
1122 bitmap_to_u32array(u32 *buf, unsigned int nwords,
1123                    const unsigned long *bitmap, unsigned int nbits)
1124 {
1125         unsigned int dst_idx = 0, src_idx = 0;
1126 
1127         while (dst_idx < nwords) {
1128                 unsigned long part = 0;
1129 
1130                 if (src_idx < BITS_TO_LONGS(nbits)) {
1131                         part = bitmap[src_idx];
1132                         if (src_idx >= nbits/BITS_PER_LONG)
1133                                 part &= BITMAP_LAST_WORD_MASK(nbits);
1134                         src_idx++;
1135                 }
1136 
1137                 buf[dst_idx++] = part & 0xffffffffUL;
1138 
1139 #if BITS_PER_LONG == 64
1140                 if (dst_idx < nwords) {
1141                         part >>= 32;
1142                         buf[dst_idx++] = part & 0xffffffffUL;
1143                 }
1144 #endif
1145         }
1146 
1147         return min_t(unsigned int, nbits, 32*nwords);
1148 }
1149 EXPORT_SYMBOL(bitmap_to_u32array);
1150 
1151 /**
1152  * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1153  * @dst:   destination buffer
1154  * @src:   bitmap to copy
1155  * @nbits: number of bits in the bitmap
1156  *
1157  * Require nbits % BITS_PER_LONG == 0.
1158  */
1159 #ifdef __BIG_ENDIAN
1160 void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits)
1161 {
1162         unsigned int i;
1163 
1164         for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1165                 if (BITS_PER_LONG == 64)
1166                         dst[i] = cpu_to_le64(src[i]);
1167                 else
1168                         dst[i] = cpu_to_le32(src[i]);
1169         }
1170 }
1171 EXPORT_SYMBOL(bitmap_copy_le);
1172 #endif
1173 

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