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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 <asm/uaccess.h>
 16 
 17 /*
 18  * bitmaps provide an array of bits, implemented using an an
 19  * array of unsigned longs.  The number of valid bits in a
 20  * given bitmap does _not_ need to be an exact multiple of
 21  * BITS_PER_LONG.
 22  *
 23  * The possible unused bits in the last, partially used word
 24  * of a bitmap are 'don't care'.  The implementation makes
 25  * no particular effort to keep them zero.  It ensures that
 26  * their value will not affect the results of any operation.
 27  * The bitmap operations that return Boolean (bitmap_empty,
 28  * for example) or scalar (bitmap_weight, for example) results
 29  * carefully filter out these unused bits from impacting their
 30  * results.
 31  *
 32  * These operations actually hold to a slightly stronger rule:
 33  * if you don't input any bitmaps to these ops that have some
 34  * unused bits set, then they won't output any set unused bits
 35  * in output bitmaps.
 36  *
 37  * The byte ordering of bitmaps is more natural on little
 38  * endian architectures.  See the big-endian headers
 39  * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
 40  * for the best explanations of this ordering.
 41  */
 42 
 43 int __bitmap_empty(const unsigned long *bitmap, int bits)
 44 {
 45         int k, lim = bits/BITS_PER_LONG;
 46         for (k = 0; k < lim; ++k)
 47                 if (bitmap[k])
 48                         return 0;
 49 
 50         if (bits % BITS_PER_LONG)
 51                 if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
 52                         return 0;
 53 
 54         return 1;
 55 }
 56 EXPORT_SYMBOL(__bitmap_empty);
 57 
 58 int __bitmap_full(const unsigned long *bitmap, int bits)
 59 {
 60         int k, lim = bits/BITS_PER_LONG;
 61         for (k = 0; k < lim; ++k)
 62                 if (~bitmap[k])
 63                         return 0;
 64 
 65         if (bits % BITS_PER_LONG)
 66                 if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
 67                         return 0;
 68 
 69         return 1;
 70 }
 71 EXPORT_SYMBOL(__bitmap_full);
 72 
 73 int __bitmap_equal(const unsigned long *bitmap1,
 74                 const unsigned long *bitmap2, int bits)
 75 {
 76         int k, lim = bits/BITS_PER_LONG;
 77         for (k = 0; k < lim; ++k)
 78                 if (bitmap1[k] != bitmap2[k])
 79                         return 0;
 80 
 81         if (bits % BITS_PER_LONG)
 82                 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
 83                         return 0;
 84 
 85         return 1;
 86 }
 87 EXPORT_SYMBOL(__bitmap_equal);
 88 
 89 void __bitmap_complement(unsigned long *dst, const unsigned long *src, int bits)
 90 {
 91         int k, lim = bits/BITS_PER_LONG;
 92         for (k = 0; k < lim; ++k)
 93                 dst[k] = ~src[k];
 94 
 95         if (bits % BITS_PER_LONG)
 96                 dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);
 97 }
 98 EXPORT_SYMBOL(__bitmap_complement);
 99 
100 /**
101  * __bitmap_shift_right - logical right shift of the bits in a bitmap
102  *   @dst : destination bitmap
103  *   @src : source bitmap
104  *   @shift : shift by this many bits
105  *   @bits : bitmap size, in bits
106  *
107  * Shifting right (dividing) means moving bits in the MS -> LS bit
108  * direction.  Zeros are fed into the vacated MS positions and the
109  * LS bits shifted off the bottom are lost.
110  */
111 void __bitmap_shift_right(unsigned long *dst,
112                         const unsigned long *src, int shift, int bits)
113 {
114         int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
115         int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
116         unsigned long mask = (1UL << left) - 1;
117         for (k = 0; off + k < lim; ++k) {
118                 unsigned long upper, lower;
119 
120                 /*
121                  * If shift is not word aligned, take lower rem bits of
122                  * word above and make them the top rem bits of result.
123                  */
124                 if (!rem || off + k + 1 >= lim)
125                         upper = 0;
126                 else {
127                         upper = src[off + k + 1];
128                         if (off + k + 1 == lim - 1 && left)
129                                 upper &= mask;
130                 }
131                 lower = src[off + k];
132                 if (left && off + k == lim - 1)
133                         lower &= mask;
134                 dst[k] = upper << (BITS_PER_LONG - rem) | lower >> rem;
135                 if (left && k == lim - 1)
136                         dst[k] &= mask;
137         }
138         if (off)
139                 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
140 }
141 EXPORT_SYMBOL(__bitmap_shift_right);
142 
143 
144 /**
145  * __bitmap_shift_left - logical left shift of the bits in a bitmap
146  *   @dst : destination bitmap
147  *   @src : source bitmap
148  *   @shift : shift by this many bits
149  *   @bits : bitmap size, in bits
150  *
151  * Shifting left (multiplying) means moving bits in the LS -> MS
152  * direction.  Zeros are fed into the vacated LS bit positions
153  * and those MS bits shifted off the top are lost.
154  */
155 
156 void __bitmap_shift_left(unsigned long *dst,
157                         const unsigned long *src, int shift, int bits)
158 {
159         int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
160         int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
161         for (k = lim - off - 1; k >= 0; --k) {
162                 unsigned long upper, lower;
163 
164                 /*
165                  * If shift is not word aligned, take upper rem bits of
166                  * word below and make them the bottom rem bits of result.
167                  */
168                 if (rem && k > 0)
169                         lower = src[k - 1];
170                 else
171                         lower = 0;
172                 upper = src[k];
173                 if (left && k == lim - 1)
174                         upper &= (1UL << left) - 1;
175                 dst[k + off] = lower  >> (BITS_PER_LONG - rem) | upper << rem;
176                 if (left && k + off == lim - 1)
177                         dst[k + off] &= (1UL << left) - 1;
178         }
179         if (off)
180                 memset(dst, 0, off*sizeof(unsigned long));
181 }
182 EXPORT_SYMBOL(__bitmap_shift_left);
183 
184 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
185                                 const unsigned long *bitmap2, int bits)
186 {
187         int k;
188         int nr = BITS_TO_LONGS(bits);
189         unsigned long result = 0;
190 
191         for (k = 0; k < nr; k++)
192                 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
193         return result != 0;
194 }
195 EXPORT_SYMBOL(__bitmap_and);
196 
197 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
198                                 const unsigned long *bitmap2, int bits)
199 {
200         int k;
201         int nr = BITS_TO_LONGS(bits);
202 
203         for (k = 0; k < nr; k++)
204                 dst[k] = bitmap1[k] | bitmap2[k];
205 }
206 EXPORT_SYMBOL(__bitmap_or);
207 
208 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
209                                 const unsigned long *bitmap2, int bits)
210 {
211         int k;
212         int nr = BITS_TO_LONGS(bits);
213 
214         for (k = 0; k < nr; k++)
215                 dst[k] = bitmap1[k] ^ bitmap2[k];
216 }
217 EXPORT_SYMBOL(__bitmap_xor);
218 
219 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
220                                 const unsigned long *bitmap2, int bits)
221 {
222         int k;
223         int nr = BITS_TO_LONGS(bits);
224         unsigned long result = 0;
225 
226         for (k = 0; k < nr; k++)
227                 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
228         return result != 0;
229 }
230 EXPORT_SYMBOL(__bitmap_andnot);
231 
232 int __bitmap_intersects(const unsigned long *bitmap1,
233                                 const unsigned long *bitmap2, int bits)
234 {
235         int k, lim = bits/BITS_PER_LONG;
236         for (k = 0; k < lim; ++k)
237                 if (bitmap1[k] & bitmap2[k])
238                         return 1;
239 
240         if (bits % BITS_PER_LONG)
241                 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
242                         return 1;
243         return 0;
244 }
245 EXPORT_SYMBOL(__bitmap_intersects);
246 
247 int __bitmap_subset(const unsigned long *bitmap1,
248                                 const unsigned long *bitmap2, int bits)
249 {
250         int k, lim = bits/BITS_PER_LONG;
251         for (k = 0; k < lim; ++k)
252                 if (bitmap1[k] & ~bitmap2[k])
253                         return 0;
254 
255         if (bits % BITS_PER_LONG)
256                 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
257                         return 0;
258         return 1;
259 }
260 EXPORT_SYMBOL(__bitmap_subset);
261 
262 int __bitmap_weight(const unsigned long *bitmap, int bits)
263 {
264         int k, w = 0, lim = bits/BITS_PER_LONG;
265 
266         for (k = 0; k < lim; k++)
267                 w += hweight_long(bitmap[k]);
268 
269         if (bits % BITS_PER_LONG)
270                 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
271 
272         return w;
273 }
274 EXPORT_SYMBOL(__bitmap_weight);
275 
276 void bitmap_set(unsigned long *map, int start, int nr)
277 {
278         unsigned long *p = map + BIT_WORD(start);
279         const int size = start + nr;
280         int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
281         unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
282 
283         while (nr - bits_to_set >= 0) {
284                 *p |= mask_to_set;
285                 nr -= bits_to_set;
286                 bits_to_set = BITS_PER_LONG;
287                 mask_to_set = ~0UL;
288                 p++;
289         }
290         if (nr) {
291                 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
292                 *p |= mask_to_set;
293         }
294 }
295 EXPORT_SYMBOL(bitmap_set);
296 
297 void bitmap_clear(unsigned long *map, int start, int nr)
298 {
299         unsigned long *p = map + BIT_WORD(start);
300         const int size = start + nr;
301         int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
302         unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
303 
304         while (nr - bits_to_clear >= 0) {
305                 *p &= ~mask_to_clear;
306                 nr -= bits_to_clear;
307                 bits_to_clear = BITS_PER_LONG;
308                 mask_to_clear = ~0UL;
309                 p++;
310         }
311         if (nr) {
312                 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
313                 *p &= ~mask_to_clear;
314         }
315 }
316 EXPORT_SYMBOL(bitmap_clear);
317 
318 /*
319  * bitmap_find_next_zero_area - find a contiguous aligned zero area
320  * @map: The address to base the search on
321  * @size: The bitmap size in bits
322  * @start: The bitnumber to start searching at
323  * @nr: The number of zeroed bits we're looking for
324  * @align_mask: Alignment mask for zero area
325  *
326  * The @align_mask should be one less than a power of 2; the effect is that
327  * the bit offset of all zero areas this function finds is multiples of that
328  * power of 2. A @align_mask of 0 means no alignment is required.
329  */
330 unsigned long bitmap_find_next_zero_area(unsigned long *map,
331                                          unsigned long size,
332                                          unsigned long start,
333                                          unsigned int nr,
334                                          unsigned long align_mask)
335 {
336         unsigned long index, end, i;
337 again:
338         index = find_next_zero_bit(map, size, start);
339 
340         /* Align allocation */
341         index = __ALIGN_MASK(index, align_mask);
342 
343         end = index + nr;
344         if (end > size)
345                 return end;
346         i = find_next_bit(map, end, index);
347         if (i < end) {
348                 start = i + 1;
349                 goto again;
350         }
351         return index;
352 }
353 EXPORT_SYMBOL(bitmap_find_next_zero_area);
354 
355 /*
356  * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
357  * second version by Paul Jackson, third by Joe Korty.
358  */
359 
360 #define CHUNKSZ                         32
361 #define nbits_to_hold_value(val)        fls(val)
362 #define BASEDEC 10              /* fancier cpuset lists input in decimal */
363 
364 /**
365  * bitmap_scnprintf - convert bitmap to an ASCII hex string.
366  * @buf: byte buffer into which string is placed
367  * @buflen: reserved size of @buf, in bytes
368  * @maskp: pointer to bitmap to convert
369  * @nmaskbits: size of bitmap, in bits
370  *
371  * Exactly @nmaskbits bits are displayed.  Hex digits are grouped into
372  * comma-separated sets of eight digits per set.  Returns the number of
373  * characters which were written to *buf, excluding the trailing \0.
374  */
375 int bitmap_scnprintf(char *buf, unsigned int buflen,
376         const unsigned long *maskp, int nmaskbits)
377 {
378         int i, word, bit, len = 0;
379         unsigned long val;
380         const char *sep = "";
381         int chunksz;
382         u32 chunkmask;
383 
384         chunksz = nmaskbits & (CHUNKSZ - 1);
385         if (chunksz == 0)
386                 chunksz = CHUNKSZ;
387 
388         i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ;
389         for (; i >= 0; i -= CHUNKSZ) {
390                 chunkmask = ((1ULL << chunksz) - 1);
391                 word = i / BITS_PER_LONG;
392                 bit = i % BITS_PER_LONG;
393                 val = (maskp[word] >> bit) & chunkmask;
394                 len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep,
395                         (chunksz+3)/4, val);
396                 chunksz = CHUNKSZ;
397                 sep = ",";
398         }
399         return len;
400 }
401 EXPORT_SYMBOL(bitmap_scnprintf);
402 
403 /**
404  * __bitmap_parse - convert an ASCII hex string into a bitmap.
405  * @buf: pointer to buffer containing string.
406  * @buflen: buffer size in bytes.  If string is smaller than this
407  *    then it must be terminated with a \0.
408  * @is_user: location of buffer, 0 indicates kernel space
409  * @maskp: pointer to bitmap array that will contain result.
410  * @nmaskbits: size of bitmap, in bits.
411  *
412  * Commas group hex digits into chunks.  Each chunk defines exactly 32
413  * bits of the resultant bitmask.  No chunk may specify a value larger
414  * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
415  * then leading 0-bits are prepended.  %-EINVAL is returned for illegal
416  * characters and for grouping errors such as "1,,5", ",44", "," and "".
417  * Leading and trailing whitespace accepted, but not embedded whitespace.
418  */
419 int __bitmap_parse(const char *buf, unsigned int buflen,
420                 int is_user, unsigned long *maskp,
421                 int nmaskbits)
422 {
423         int c, old_c, totaldigits, ndigits, nchunks, nbits;
424         u32 chunk;
425         const char __user __force *ubuf = (const char __user __force *)buf;
426 
427         bitmap_zero(maskp, nmaskbits);
428 
429         nchunks = nbits = totaldigits = c = 0;
430         do {
431                 chunk = ndigits = 0;
432 
433                 /* Get the next chunk of the bitmap */
434                 while (buflen) {
435                         old_c = c;
436                         if (is_user) {
437                                 if (__get_user(c, ubuf++))
438                                         return -EFAULT;
439                         }
440                         else
441                                 c = *buf++;
442                         buflen--;
443                         if (isspace(c))
444                                 continue;
445 
446                         /*
447                          * If the last character was a space and the current
448                          * character isn't '\0', we've got embedded whitespace.
449                          * This is a no-no, so throw an error.
450                          */
451                         if (totaldigits && c && isspace(old_c))
452                                 return -EINVAL;
453 
454                         /* A '\0' or a ',' signal the end of the chunk */
455                         if (c == '\0' || c == ',')
456                                 break;
457 
458                         if (!isxdigit(c))
459                                 return -EINVAL;
460 
461                         /*
462                          * Make sure there are at least 4 free bits in 'chunk'.
463                          * If not, this hexdigit will overflow 'chunk', so
464                          * throw an error.
465                          */
466                         if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
467                                 return -EOVERFLOW;
468 
469                         chunk = (chunk << 4) | hex_to_bin(c);
470                         ndigits++; totaldigits++;
471                 }
472                 if (ndigits == 0)
473                         return -EINVAL;
474                 if (nchunks == 0 && chunk == 0)
475                         continue;
476 
477                 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
478                 *maskp |= chunk;
479                 nchunks++;
480                 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
481                 if (nbits > nmaskbits)
482                         return -EOVERFLOW;
483         } while (buflen && c == ',');
484 
485         return 0;
486 }
487 EXPORT_SYMBOL(__bitmap_parse);
488 
489 /**
490  * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
491  *
492  * @ubuf: pointer to user buffer containing string.
493  * @ulen: buffer size in bytes.  If string is smaller than this
494  *    then it must be terminated with a \0.
495  * @maskp: pointer to bitmap array that will contain result.
496  * @nmaskbits: size of bitmap, in bits.
497  *
498  * Wrapper for __bitmap_parse(), providing it with user buffer.
499  *
500  * We cannot have this as an inline function in bitmap.h because it needs
501  * linux/uaccess.h to get the access_ok() declaration and this causes
502  * cyclic dependencies.
503  */
504 int bitmap_parse_user(const char __user *ubuf,
505                         unsigned int ulen, unsigned long *maskp,
506                         int nmaskbits)
507 {
508         if (!access_ok(VERIFY_READ, ubuf, ulen))
509                 return -EFAULT;
510         return __bitmap_parse((const char __force *)ubuf,
511                                 ulen, 1, maskp, nmaskbits);
512 
513 }
514 EXPORT_SYMBOL(bitmap_parse_user);
515 
516 /*
517  * bscnl_emit(buf, buflen, rbot, rtop, bp)
518  *
519  * Helper routine for bitmap_scnlistprintf().  Write decimal number
520  * or range to buf, suppressing output past buf+buflen, with optional
521  * comma-prefix.  Return len of what was written to *buf, excluding the
522  * trailing \0.
523  */
524 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
525 {
526         if (len > 0)
527                 len += scnprintf(buf + len, buflen - len, ",");
528         if (rbot == rtop)
529                 len += scnprintf(buf + len, buflen - len, "%d", rbot);
530         else
531                 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
532         return len;
533 }
534 
535 /**
536  * bitmap_scnlistprintf - convert bitmap to list format ASCII string
537  * @buf: byte buffer into which string is placed
538  * @buflen: reserved size of @buf, in bytes
539  * @maskp: pointer to bitmap to convert
540  * @nmaskbits: size of bitmap, in bits
541  *
542  * Output format is a comma-separated list of decimal numbers and
543  * ranges.  Consecutively set bits are shown as two hyphen-separated
544  * decimal numbers, the smallest and largest bit numbers set in
545  * the range.  Output format is compatible with the format
546  * accepted as input by bitmap_parselist().
547  *
548  * The return value is the number of characters which were written to *buf
549  * excluding the trailing '\0', as per ISO C99's scnprintf.
550  */
551 int bitmap_scnlistprintf(char *buf, unsigned int buflen,
552         const unsigned long *maskp, int nmaskbits)
553 {
554         int len = 0;
555         /* current bit is 'cur', most recently seen range is [rbot, rtop] */
556         int cur, rbot, rtop;
557 
558         if (buflen == 0)
559                 return 0;
560         buf[0] = 0;
561 
562         rbot = cur = find_first_bit(maskp, nmaskbits);
563         while (cur < nmaskbits) {
564                 rtop = cur;
565                 cur = find_next_bit(maskp, nmaskbits, cur+1);
566                 if (cur >= nmaskbits || cur > rtop + 1) {
567                         len = bscnl_emit(buf, buflen, rbot, rtop, len);
568                         rbot = cur;
569                 }
570         }
571         return len;
572 }
573 EXPORT_SYMBOL(bitmap_scnlistprintf);
574 
575 /**
576  * __bitmap_parselist - convert list format ASCII string to bitmap
577  * @buf: read nul-terminated user string from this buffer
578  * @buflen: buffer size in bytes.  If string is smaller than this
579  *    then it must be terminated with a \0.
580  * @is_user: location of buffer, 0 indicates kernel space
581  * @maskp: write resulting mask here
582  * @nmaskbits: number of bits in mask to be written
583  *
584  * Input format is a comma-separated list of decimal numbers and
585  * ranges.  Consecutively set bits are shown as two hyphen-separated
586  * decimal numbers, the smallest and largest bit numbers set in
587  * the range.
588  *
589  * Returns 0 on success, -errno on invalid input strings.
590  * Error values:
591  *    %-EINVAL: second number in range smaller than first
592  *    %-EINVAL: invalid character in string
593  *    %-ERANGE: bit number specified too large for mask
594  */
595 static int __bitmap_parselist(const char *buf, unsigned int buflen,
596                 int is_user, unsigned long *maskp,
597                 int nmaskbits)
598 {
599         unsigned a, b;
600         int c, old_c, totaldigits;
601         const char __user __force *ubuf = (const char __user __force *)buf;
602         int exp_digit, in_range;
603 
604         totaldigits = c = 0;
605         bitmap_zero(maskp, nmaskbits);
606         do {
607                 exp_digit = 1;
608                 in_range = 0;
609                 a = b = 0;
610 
611                 /* Get the next cpu# or a range of cpu#'s */
612                 while (buflen) {
613                         old_c = c;
614                         if (is_user) {
615                                 if (__get_user(c, ubuf++))
616                                         return -EFAULT;
617                         } else
618                                 c = *buf++;
619                         buflen--;
620                         if (isspace(c))
621                                 continue;
622 
623                         /*
624                          * If the last character was a space and the current
625                          * character isn't '\0', we've got embedded whitespace.
626                          * This is a no-no, so throw an error.
627                          */
628                         if (totaldigits && c && isspace(old_c))
629                                 return -EINVAL;
630 
631                         /* A '\0' or a ',' signal the end of a cpu# or range */
632                         if (c == '\0' || c == ',')
633                                 break;
634 
635                         if (c == '-') {
636                                 if (exp_digit || in_range)
637                                         return -EINVAL;
638                                 b = 0;
639                                 in_range = 1;
640                                 exp_digit = 1;
641                                 continue;
642                         }
643 
644                         if (!isdigit(c))
645                                 return -EINVAL;
646 
647                         b = b * 10 + (c - '');
648                         if (!in_range)
649                                 a = b;
650                         exp_digit = 0;
651                         totaldigits++;
652                 }
653                 if (!(a <= b))
654                         return -EINVAL;
655                 if (b >= nmaskbits)
656                         return -ERANGE;
657                 while (a <= b) {
658                         set_bit(a, maskp);
659                         a++;
660                 }
661         } while (buflen && c == ',');
662         return 0;
663 }
664 
665 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
666 {
667         char *nl  = strchr(bp, '\n');
668         int len;
669 
670         if (nl)
671                 len = nl - bp;
672         else
673                 len = strlen(bp);
674 
675         return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
676 }
677 EXPORT_SYMBOL(bitmap_parselist);
678 
679 
680 /**
681  * bitmap_parselist_user()
682  *
683  * @ubuf: pointer to user buffer containing string.
684  * @ulen: buffer size in bytes.  If string is smaller than this
685  *    then it must be terminated with a \0.
686  * @maskp: pointer to bitmap array that will contain result.
687  * @nmaskbits: size of bitmap, in bits.
688  *
689  * Wrapper for bitmap_parselist(), providing it with user buffer.
690  *
691  * We cannot have this as an inline function in bitmap.h because it needs
692  * linux/uaccess.h to get the access_ok() declaration and this causes
693  * cyclic dependencies.
694  */
695 int bitmap_parselist_user(const char __user *ubuf,
696                         unsigned int ulen, unsigned long *maskp,
697                         int nmaskbits)
698 {
699         if (!access_ok(VERIFY_READ, ubuf, ulen))
700                 return -EFAULT;
701         return __bitmap_parselist((const char __force *)ubuf,
702                                         ulen, 1, maskp, nmaskbits);
703 }
704 EXPORT_SYMBOL(bitmap_parselist_user);
705 
706 
707 /**
708  * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
709  *      @buf: pointer to a bitmap
710  *      @pos: a bit position in @buf (0 <= @pos < @bits)
711  *      @bits: number of valid bit positions in @buf
712  *
713  * Map the bit at position @pos in @buf (of length @bits) to the
714  * ordinal of which set bit it is.  If it is not set or if @pos
715  * is not a valid bit position, map to -1.
716  *
717  * If for example, just bits 4 through 7 are set in @buf, then @pos
718  * values 4 through 7 will get mapped to 0 through 3, respectively,
719  * and other @pos values will get mapped to 0.  When @pos value 7
720  * gets mapped to (returns) @ord value 3 in this example, that means
721  * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
722  *
723  * The bit positions 0 through @bits are valid positions in @buf.
724  */
725 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
726 {
727         int i, ord;
728 
729         if (pos < 0 || pos >= bits || !test_bit(pos, buf))
730                 return -1;
731 
732         i = find_first_bit(buf, bits);
733         ord = 0;
734         while (i < pos) {
735                 i = find_next_bit(buf, bits, i + 1);
736                 ord++;
737         }
738         BUG_ON(i != pos);
739 
740         return ord;
741 }
742 
743 /**
744  * bitmap_ord_to_pos - find position of n-th set bit in bitmap
745  *      @buf: pointer to bitmap
746  *      @ord: ordinal bit position (n-th set bit, n >= 0)
747  *      @bits: number of valid bit positions in @buf
748  *
749  * Map the ordinal offset of bit @ord in @buf to its position in @buf.
750  * Value of @ord should be in range 0 <= @ord < weight(buf), else
751  * results are undefined.
752  *
753  * If for example, just bits 4 through 7 are set in @buf, then @ord
754  * values 0 through 3 will get mapped to 4 through 7, respectively,
755  * and all other @ord values return undefined values.  When @ord value 3
756  * gets mapped to (returns) @pos value 7 in this example, that means
757  * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
758  *
759  * The bit positions 0 through @bits are valid positions in @buf.
760  */
761 int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
762 {
763         int pos = 0;
764 
765         if (ord >= 0 && ord < bits) {
766                 int i;
767 
768                 for (i = find_first_bit(buf, bits);
769                      i < bits && ord > 0;
770                      i = find_next_bit(buf, bits, i + 1))
771                         ord--;
772                 if (i < bits && ord == 0)
773                         pos = i;
774         }
775 
776         return pos;
777 }
778 
779 /**
780  * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
781  *      @dst: remapped result
782  *      @src: subset to be remapped
783  *      @old: defines domain of map
784  *      @new: defines range of map
785  *      @bits: number of bits in each of these bitmaps
786  *
787  * Let @old and @new define a mapping of bit positions, such that
788  * whatever position is held by the n-th set bit in @old is mapped
789  * to the n-th set bit in @new.  In the more general case, allowing
790  * for the possibility that the weight 'w' of @new is less than the
791  * weight of @old, map the position of the n-th set bit in @old to
792  * the position of the m-th set bit in @new, where m == n % w.
793  *
794  * If either of the @old and @new bitmaps are empty, or if @src and
795  * @dst point to the same location, then this routine copies @src
796  * to @dst.
797  *
798  * The positions of unset bits in @old are mapped to themselves
799  * (the identify map).
800  *
801  * Apply the above specified mapping to @src, placing the result in
802  * @dst, clearing any bits previously set in @dst.
803  *
804  * For example, lets say that @old has bits 4 through 7 set, and
805  * @new has bits 12 through 15 set.  This defines the mapping of bit
806  * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
807  * bit positions unchanged.  So if say @src comes into this routine
808  * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
809  * 13 and 15 set.
810  */
811 void bitmap_remap(unsigned long *dst, const unsigned long *src,
812                 const unsigned long *old, const unsigned long *new,
813                 int bits)
814 {
815         int oldbit, w;
816 
817         if (dst == src)         /* following doesn't handle inplace remaps */
818                 return;
819         bitmap_zero(dst, bits);
820 
821         w = bitmap_weight(new, bits);
822         for_each_set_bit(oldbit, src, bits) {
823                 int n = bitmap_pos_to_ord(old, oldbit, bits);
824 
825                 if (n < 0 || w == 0)
826                         set_bit(oldbit, dst);   /* identity map */
827                 else
828                         set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);
829         }
830 }
831 EXPORT_SYMBOL(bitmap_remap);
832 
833 /**
834  * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
835  *      @oldbit: bit position to be mapped
836  *      @old: defines domain of map
837  *      @new: defines range of map
838  *      @bits: number of bits in each of these bitmaps
839  *
840  * Let @old and @new define a mapping of bit positions, such that
841  * whatever position is held by the n-th set bit in @old is mapped
842  * to the n-th set bit in @new.  In the more general case, allowing
843  * for the possibility that the weight 'w' of @new is less than the
844  * weight of @old, map the position of the n-th set bit in @old to
845  * the position of the m-th set bit in @new, where m == n % w.
846  *
847  * The positions of unset bits in @old are mapped to themselves
848  * (the identify map).
849  *
850  * Apply the above specified mapping to bit position @oldbit, returning
851  * the new bit position.
852  *
853  * For example, lets say that @old has bits 4 through 7 set, and
854  * @new has bits 12 through 15 set.  This defines the mapping of bit
855  * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
856  * bit positions unchanged.  So if say @oldbit is 5, then this routine
857  * returns 13.
858  */
859 int bitmap_bitremap(int oldbit, const unsigned long *old,
860                                 const unsigned long *new, int bits)
861 {
862         int w = bitmap_weight(new, bits);
863         int n = bitmap_pos_to_ord(old, oldbit, bits);
864         if (n < 0 || w == 0)
865                 return oldbit;
866         else
867                 return bitmap_ord_to_pos(new, n % w, bits);
868 }
869 EXPORT_SYMBOL(bitmap_bitremap);
870 
871 /**
872  * bitmap_onto - translate one bitmap relative to another
873  *      @dst: resulting translated bitmap
874  *      @orig: original untranslated bitmap
875  *      @relmap: bitmap relative to which translated
876  *      @bits: number of bits in each of these bitmaps
877  *
878  * Set the n-th bit of @dst iff there exists some m such that the
879  * n-th bit of @relmap is set, the m-th bit of @orig is set, and
880  * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
881  * (If you understood the previous sentence the first time your
882  * read it, you're overqualified for your current job.)
883  *
884  * In other words, @orig is mapped onto (surjectively) @dst,
885  * using the the map { <n, m> | the n-th bit of @relmap is the
886  * m-th set bit of @relmap }.
887  *
888  * Any set bits in @orig above bit number W, where W is the
889  * weight of (number of set bits in) @relmap are mapped nowhere.
890  * In particular, if for all bits m set in @orig, m >= W, then
891  * @dst will end up empty.  In situations where the possibility
892  * of such an empty result is not desired, one way to avoid it is
893  * to use the bitmap_fold() operator, below, to first fold the
894  * @orig bitmap over itself so that all its set bits x are in the
895  * range 0 <= x < W.  The bitmap_fold() operator does this by
896  * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
897  *
898  * Example [1] for bitmap_onto():
899  *  Let's say @relmap has bits 30-39 set, and @orig has bits
900  *  1, 3, 5, 7, 9 and 11 set.  Then on return from this routine,
901  *  @dst will have bits 31, 33, 35, 37 and 39 set.
902  *
903  *  When bit 0 is set in @orig, it means turn on the bit in
904  *  @dst corresponding to whatever is the first bit (if any)
905  *  that is turned on in @relmap.  Since bit 0 was off in the
906  *  above example, we leave off that bit (bit 30) in @dst.
907  *
908  *  When bit 1 is set in @orig (as in the above example), it
909  *  means turn on the bit in @dst corresponding to whatever
910  *  is the second bit that is turned on in @relmap.  The second
911  *  bit in @relmap that was turned on in the above example was
912  *  bit 31, so we turned on bit 31 in @dst.
913  *
914  *  Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
915  *  because they were the 4th, 6th, 8th and 10th set bits
916  *  set in @relmap, and the 4th, 6th, 8th and 10th bits of
917  *  @orig (i.e. bits 3, 5, 7 and 9) were also set.
918  *
919  *  When bit 11 is set in @orig, it means turn on the bit in
920  *  @dst corresponding to whatever is the twelfth bit that is
921  *  turned on in @relmap.  In the above example, there were
922  *  only ten bits turned on in @relmap (30..39), so that bit
923  *  11 was set in @orig had no affect on @dst.
924  *
925  * Example [2] for bitmap_fold() + bitmap_onto():
926  *  Let's say @relmap has these ten bits set:
927  *              40 41 42 43 45 48 53 61 74 95
928  *  (for the curious, that's 40 plus the first ten terms of the
929  *  Fibonacci sequence.)
930  *
931  *  Further lets say we use the following code, invoking
932  *  bitmap_fold() then bitmap_onto, as suggested above to
933  *  avoid the possitility of an empty @dst result:
934  *
935  *      unsigned long *tmp;     // a temporary bitmap's bits
936  *
937  *      bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
938  *      bitmap_onto(dst, tmp, relmap, bits);
939  *
940  *  Then this table shows what various values of @dst would be, for
941  *  various @orig's.  I list the zero-based positions of each set bit.
942  *  The tmp column shows the intermediate result, as computed by
943  *  using bitmap_fold() to fold the @orig bitmap modulo ten
944  *  (the weight of @relmap).
945  *
946  *      @orig           tmp            @dst
947  *      0                0             40
948  *      1                1             41
949  *      9                9             95
950  *      10               0             40 (*)
951  *      1 3 5 7          1 3 5 7       41 43 48 61
952  *      0 1 2 3 4        0 1 2 3 4     40 41 42 43 45
953  *      0 9 18 27        0 9 8 7       40 61 74 95
954  *      0 10 20 30       0             40
955  *      0 11 22 33       0 1 2 3       40 41 42 43
956  *      0 12 24 36       0 2 4 6       40 42 45 53
957  *      78 102 211       1 2 8         41 42 74 (*)
958  *
959  * (*) For these marked lines, if we hadn't first done bitmap_fold()
960  *     into tmp, then the @dst result would have been empty.
961  *
962  * If either of @orig or @relmap is empty (no set bits), then @dst
963  * will be returned empty.
964  *
965  * If (as explained above) the only set bits in @orig are in positions
966  * m where m >= W, (where W is the weight of @relmap) then @dst will
967  * once again be returned empty.
968  *
969  * All bits in @dst not set by the above rule are cleared.
970  */
971 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
972                         const unsigned long *relmap, int bits)
973 {
974         int n, m;               /* same meaning as in above comment */
975 
976         if (dst == orig)        /* following doesn't handle inplace mappings */
977                 return;
978         bitmap_zero(dst, bits);
979 
980         /*
981          * The following code is a more efficient, but less
982          * obvious, equivalent to the loop:
983          *      for (m = 0; m < bitmap_weight(relmap, bits); m++) {
984          *              n = bitmap_ord_to_pos(orig, m, bits);
985          *              if (test_bit(m, orig))
986          *                      set_bit(n, dst);
987          *      }
988          */
989 
990         m = 0;
991         for_each_set_bit(n, relmap, bits) {
992                 /* m == bitmap_pos_to_ord(relmap, n, bits) */
993                 if (test_bit(m, orig))
994                         set_bit(n, dst);
995                 m++;
996         }
997 }
998 EXPORT_SYMBOL(bitmap_onto);
999 
1000 /**
1001  * bitmap_fold - fold larger bitmap into smaller, modulo specified size
1002  *      @dst: resulting smaller bitmap
1003  *      @orig: original larger bitmap
1004  *      @sz: specified size
1005  *      @bits: number of bits in each of these bitmaps
1006  *
1007  * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
1008  * Clear all other bits in @dst.  See further the comment and
1009  * Example [2] for bitmap_onto() for why and how to use this.
1010  */
1011 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
1012                         int sz, int bits)
1013 {
1014         int oldbit;
1015 
1016         if (dst == orig)        /* following doesn't handle inplace mappings */
1017                 return;
1018         bitmap_zero(dst, bits);
1019 
1020         for_each_set_bit(oldbit, orig, bits)
1021                 set_bit(oldbit % sz, dst);
1022 }
1023 EXPORT_SYMBOL(bitmap_fold);
1024 
1025 /*
1026  * Common code for bitmap_*_region() routines.
1027  *      bitmap: array of unsigned longs corresponding to the bitmap
1028  *      pos: the beginning of the region
1029  *      order: region size (log base 2 of number of bits)
1030  *      reg_op: operation(s) to perform on that region of bitmap
1031  *
1032  * Can set, verify and/or release a region of bits in a bitmap,
1033  * depending on which combination of REG_OP_* flag bits is set.
1034  *
1035  * A region of a bitmap is a sequence of bits in the bitmap, of
1036  * some size '1 << order' (a power of two), aligned to that same
1037  * '1 << order' power of two.
1038  *
1039  * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
1040  * Returns 0 in all other cases and reg_ops.
1041  */
1042 
1043 enum {
1044         REG_OP_ISFREE,          /* true if region is all zero bits */
1045         REG_OP_ALLOC,           /* set all bits in region */
1046         REG_OP_RELEASE,         /* clear all bits in region */
1047 };
1048 
1049 static int __reg_op(unsigned long *bitmap, int pos, int order, int reg_op)
1050 {
1051         int nbits_reg;          /* number of bits in region */
1052         int index;              /* index first long of region in bitmap */
1053         int offset;             /* bit offset region in bitmap[index] */
1054         int nlongs_reg;         /* num longs spanned by region in bitmap */
1055         int nbitsinlong;        /* num bits of region in each spanned long */
1056         unsigned long mask;     /* bitmask for one long of region */
1057         int i;                  /* scans bitmap by longs */
1058         int ret = 0;            /* return value */
1059 
1060         /*
1061          * Either nlongs_reg == 1 (for small orders that fit in one long)
1062          * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1063          */
1064         nbits_reg = 1 << order;
1065         index = pos / BITS_PER_LONG;
1066         offset = pos - (index * BITS_PER_LONG);
1067         nlongs_reg = BITS_TO_LONGS(nbits_reg);
1068         nbitsinlong = min(nbits_reg,  BITS_PER_LONG);
1069 
1070         /*
1071          * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1072          * overflows if nbitsinlong == BITS_PER_LONG.
1073          */
1074         mask = (1UL << (nbitsinlong - 1));
1075         mask += mask - 1;
1076         mask <<= offset;
1077 
1078         switch (reg_op) {
1079         case REG_OP_ISFREE:
1080                 for (i = 0; i < nlongs_reg; i++) {
1081                         if (bitmap[index + i] & mask)
1082                                 goto done;
1083                 }
1084                 ret = 1;        /* all bits in region free (zero) */
1085                 break;
1086 
1087         case REG_OP_ALLOC:
1088                 for (i = 0; i < nlongs_reg; i++)
1089                         bitmap[index + i] |= mask;
1090                 break;
1091 
1092         case REG_OP_RELEASE:
1093                 for (i = 0; i < nlongs_reg; i++)
1094                         bitmap[index + i] &= ~mask;
1095                 break;
1096         }
1097 done:
1098         return ret;
1099 }
1100 
1101 /**
1102  * bitmap_find_free_region - find a contiguous aligned mem region
1103  *      @bitmap: array of unsigned longs corresponding to the bitmap
1104  *      @bits: number of bits in the bitmap
1105  *      @order: region size (log base 2 of number of bits) to find
1106  *
1107  * Find a region of free (zero) bits in a @bitmap of @bits bits and
1108  * allocate them (set them to one).  Only consider regions of length
1109  * a power (@order) of two, aligned to that power of two, which
1110  * makes the search algorithm much faster.
1111  *
1112  * Return the bit offset in bitmap of the allocated region,
1113  * or -errno on failure.
1114  */
1115 int bitmap_find_free_region(unsigned long *bitmap, int bits, int order)
1116 {
1117         int pos, end;           /* scans bitmap by regions of size order */
1118 
1119         for (pos = 0 ; (end = pos + (1 << order)) <= bits; pos = end) {
1120                 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1121                         continue;
1122                 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1123                 return pos;
1124         }
1125         return -ENOMEM;
1126 }
1127 EXPORT_SYMBOL(bitmap_find_free_region);
1128 
1129 /**
1130  * bitmap_release_region - release allocated bitmap region
1131  *      @bitmap: array of unsigned longs corresponding to the bitmap
1132  *      @pos: beginning of bit region to release
1133  *      @order: region size (log base 2 of number of bits) to release
1134  *
1135  * This is the complement to __bitmap_find_free_region() and releases
1136  * the found region (by clearing it in the bitmap).
1137  *
1138  * No return value.
1139  */
1140 void bitmap_release_region(unsigned long *bitmap, int pos, int order)
1141 {
1142         __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1143 }
1144 EXPORT_SYMBOL(bitmap_release_region);
1145 
1146 /**
1147  * bitmap_allocate_region - allocate bitmap region
1148  *      @bitmap: array of unsigned longs corresponding to the bitmap
1149  *      @pos: beginning of bit region to allocate
1150  *      @order: region size (log base 2 of number of bits) to allocate
1151  *
1152  * Allocate (set bits in) a specified region of a bitmap.
1153  *
1154  * Return 0 on success, or %-EBUSY if specified region wasn't
1155  * free (not all bits were zero).
1156  */
1157 int bitmap_allocate_region(unsigned long *bitmap, int pos, int order)
1158 {
1159         if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1160                 return -EBUSY;
1161         __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1162         return 0;
1163 }
1164 EXPORT_SYMBOL(bitmap_allocate_region);
1165 
1166 /**
1167  * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1168  * @dst:   destination buffer
1169  * @src:   bitmap to copy
1170  * @nbits: number of bits in the bitmap
1171  *
1172  * Require nbits % BITS_PER_LONG == 0.
1173  */
1174 void bitmap_copy_le(void *dst, const unsigned long *src, int nbits)
1175 {
1176         unsigned long *d = dst;
1177         int i;
1178 
1179         for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1180                 if (BITS_PER_LONG == 64)
1181                         d[i] = cpu_to_le64(src[i]);
1182                 else
1183                         d[i] = cpu_to_le32(src[i]);
1184         }
1185 }
1186 EXPORT_SYMBOL(bitmap_copy_le);
1187 

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