Version:  2.0.40 2.2.26 2.4.37 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19

Linux/lib/bitmap.c

  1 /*
  2  * lib/bitmap.c
  3  * Helper functions for bitmap.h.
  4  *
  5  * This source code is licensed under the GNU General Public License,
  6  * Version 2.  See the file COPYING for more details.
  7  */
  8 #include <linux/export.h>
  9 #include <linux/thread_info.h>
 10 #include <linux/ctype.h>
 11 #include <linux/errno.h>
 12 #include <linux/bitmap.h>
 13 #include <linux/bitops.h>
 14 #include <linux/bug.h>
 15 
 16 #include <asm/page.h>
 17 #include <asm/uaccess.h>
 18 
 19 /*
 20  * bitmaps provide an array of bits, implemented using an an
 21  * array of unsigned longs.  The number of valid bits in a
 22  * given bitmap does _not_ need to be an exact multiple of
 23  * BITS_PER_LONG.
 24  *
 25  * The possible unused bits in the last, partially used word
 26  * of a bitmap are 'don't care'.  The implementation makes
 27  * no particular effort to keep them zero.  It ensures that
 28  * their value will not affect the results of any operation.
 29  * The bitmap operations that return Boolean (bitmap_empty,
 30  * for example) or scalar (bitmap_weight, for example) results
 31  * carefully filter out these unused bits from impacting their
 32  * results.
 33  *
 34  * These operations actually hold to a slightly stronger rule:
 35  * if you don't input any bitmaps to these ops that have some
 36  * unused bits set, then they won't output any set unused bits
 37  * in output bitmaps.
 38  *
 39  * The byte ordering of bitmaps is more natural on little
 40  * endian architectures.  See the big-endian headers
 41  * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
 42  * for the best explanations of this ordering.
 43  */
 44 
 45 int __bitmap_empty(const unsigned long *bitmap, unsigned int bits)
 46 {
 47         unsigned int k, lim = bits/BITS_PER_LONG;
 48         for (k = 0; k < lim; ++k)
 49                 if (bitmap[k])
 50                         return 0;
 51 
 52         if (bits % BITS_PER_LONG)
 53                 if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
 54                         return 0;
 55 
 56         return 1;
 57 }
 58 EXPORT_SYMBOL(__bitmap_empty);
 59 
 60 int __bitmap_full(const unsigned long *bitmap, unsigned int bits)
 61 {
 62         unsigned int k, lim = bits/BITS_PER_LONG;
 63         for (k = 0; k < lim; ++k)
 64                 if (~bitmap[k])
 65                         return 0;
 66 
 67         if (bits % BITS_PER_LONG)
 68                 if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
 69                         return 0;
 70 
 71         return 1;
 72 }
 73 EXPORT_SYMBOL(__bitmap_full);
 74 
 75 int __bitmap_equal(const unsigned long *bitmap1,
 76                 const unsigned long *bitmap2, unsigned int bits)
 77 {
 78         unsigned int k, lim = bits/BITS_PER_LONG;
 79         for (k = 0; k < lim; ++k)
 80                 if (bitmap1[k] != bitmap2[k])
 81                         return 0;
 82 
 83         if (bits % BITS_PER_LONG)
 84                 if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
 85                         return 0;
 86 
 87         return 1;
 88 }
 89 EXPORT_SYMBOL(__bitmap_equal);
 90 
 91 void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
 92 {
 93         unsigned int k, lim = bits/BITS_PER_LONG;
 94         for (k = 0; k < lim; ++k)
 95                 dst[k] = ~src[k];
 96 
 97         if (bits % BITS_PER_LONG)
 98                 dst[k] = ~src[k];
 99 }
100 EXPORT_SYMBOL(__bitmap_complement);
101 
102 /**
103  * __bitmap_shift_right - logical right shift of the bits in a bitmap
104  *   @dst : destination bitmap
105  *   @src : source bitmap
106  *   @shift : shift by this many bits
107  *   @bits : bitmap size, in bits
108  *
109  * Shifting right (dividing) means moving bits in the MS -> LS bit
110  * direction.  Zeros are fed into the vacated MS positions and the
111  * LS bits shifted off the bottom are lost.
112  */
113 void __bitmap_shift_right(unsigned long *dst,
114                         const unsigned long *src, int shift, int bits)
115 {
116         int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
117         int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
118         unsigned long mask = (1UL << left) - 1;
119         for (k = 0; off + k < lim; ++k) {
120                 unsigned long upper, lower;
121 
122                 /*
123                  * If shift is not word aligned, take lower rem bits of
124                  * word above and make them the top rem bits of result.
125                  */
126                 if (!rem || off + k + 1 >= lim)
127                         upper = 0;
128                 else {
129                         upper = src[off + k + 1];
130                         if (off + k + 1 == lim - 1 && left)
131                                 upper &= mask;
132                 }
133                 lower = src[off + k];
134                 if (left && off + k == lim - 1)
135                         lower &= mask;
136                 dst[k] = lower >> rem;
137                 if (rem)
138                         dst[k] |= upper << (BITS_PER_LONG - rem);
139                 if (left && k == lim - 1)
140                         dst[k] &= mask;
141         }
142         if (off)
143                 memset(&dst[lim - off], 0, off*sizeof(unsigned long));
144 }
145 EXPORT_SYMBOL(__bitmap_shift_right);
146 
147 
148 /**
149  * __bitmap_shift_left - logical left shift of the bits in a bitmap
150  *   @dst : destination bitmap
151  *   @src : source bitmap
152  *   @shift : shift by this many bits
153  *   @bits : bitmap size, in bits
154  *
155  * Shifting left (multiplying) means moving bits in the LS -> MS
156  * direction.  Zeros are fed into the vacated LS bit positions
157  * and those MS bits shifted off the top are lost.
158  */
159 
160 void __bitmap_shift_left(unsigned long *dst,
161                         const unsigned long *src, int shift, int bits)
162 {
163         int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
164         int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
165         for (k = lim - off - 1; k >= 0; --k) {
166                 unsigned long upper, lower;
167 
168                 /*
169                  * If shift is not word aligned, take upper rem bits of
170                  * word below and make them the bottom rem bits of result.
171                  */
172                 if (rem && k > 0)
173                         lower = src[k - 1];
174                 else
175                         lower = 0;
176                 upper = src[k];
177                 if (left && k == lim - 1)
178                         upper &= (1UL << left) - 1;
179                 dst[k + off] = upper << rem;
180                 if (rem)
181                         dst[k + off] |= lower >> (BITS_PER_LONG - rem);
182                 if (left && k + off == lim - 1)
183                         dst[k + off] &= (1UL << left) - 1;
184         }
185         if (off)
186                 memset(dst, 0, off*sizeof(unsigned long));
187 }
188 EXPORT_SYMBOL(__bitmap_shift_left);
189 
190 int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
191                                 const unsigned long *bitmap2, unsigned int bits)
192 {
193         unsigned int k;
194         unsigned int lim = bits/BITS_PER_LONG;
195         unsigned long result = 0;
196 
197         for (k = 0; k < lim; k++)
198                 result |= (dst[k] = bitmap1[k] & bitmap2[k]);
199         if (bits % BITS_PER_LONG)
200                 result |= (dst[k] = bitmap1[k] & bitmap2[k] &
201                            BITMAP_LAST_WORD_MASK(bits));
202         return result != 0;
203 }
204 EXPORT_SYMBOL(__bitmap_and);
205 
206 void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
207                                 const unsigned long *bitmap2, unsigned int bits)
208 {
209         unsigned int k;
210         unsigned int nr = BITS_TO_LONGS(bits);
211 
212         for (k = 0; k < nr; k++)
213                 dst[k] = bitmap1[k] | bitmap2[k];
214 }
215 EXPORT_SYMBOL(__bitmap_or);
216 
217 void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
218                                 const unsigned long *bitmap2, unsigned int bits)
219 {
220         unsigned int k;
221         unsigned int nr = BITS_TO_LONGS(bits);
222 
223         for (k = 0; k < nr; k++)
224                 dst[k] = bitmap1[k] ^ bitmap2[k];
225 }
226 EXPORT_SYMBOL(__bitmap_xor);
227 
228 int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
229                                 const unsigned long *bitmap2, unsigned int bits)
230 {
231         unsigned int k;
232         unsigned int lim = bits/BITS_PER_LONG;
233         unsigned long result = 0;
234 
235         for (k = 0; k < lim; k++)
236                 result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
237         if (bits % BITS_PER_LONG)
238                 result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
239                            BITMAP_LAST_WORD_MASK(bits));
240         return result != 0;
241 }
242 EXPORT_SYMBOL(__bitmap_andnot);
243 
244 int __bitmap_intersects(const unsigned long *bitmap1,
245                         const unsigned long *bitmap2, unsigned int bits)
246 {
247         unsigned int k, lim = bits/BITS_PER_LONG;
248         for (k = 0; k < lim; ++k)
249                 if (bitmap1[k] & bitmap2[k])
250                         return 1;
251 
252         if (bits % BITS_PER_LONG)
253                 if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
254                         return 1;
255         return 0;
256 }
257 EXPORT_SYMBOL(__bitmap_intersects);
258 
259 int __bitmap_subset(const unsigned long *bitmap1,
260                     const unsigned long *bitmap2, unsigned int bits)
261 {
262         unsigned int k, lim = bits/BITS_PER_LONG;
263         for (k = 0; k < lim; ++k)
264                 if (bitmap1[k] & ~bitmap2[k])
265                         return 0;
266 
267         if (bits % BITS_PER_LONG)
268                 if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
269                         return 0;
270         return 1;
271 }
272 EXPORT_SYMBOL(__bitmap_subset);
273 
274 int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
275 {
276         unsigned int k, lim = bits/BITS_PER_LONG;
277         int w = 0;
278 
279         for (k = 0; k < lim; k++)
280                 w += hweight_long(bitmap[k]);
281 
282         if (bits % BITS_PER_LONG)
283                 w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
284 
285         return w;
286 }
287 EXPORT_SYMBOL(__bitmap_weight);
288 
289 void bitmap_set(unsigned long *map, unsigned int start, int len)
290 {
291         unsigned long *p = map + BIT_WORD(start);
292         const unsigned int size = start + len;
293         int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
294         unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
295 
296         while (len - bits_to_set >= 0) {
297                 *p |= mask_to_set;
298                 len -= bits_to_set;
299                 bits_to_set = BITS_PER_LONG;
300                 mask_to_set = ~0UL;
301                 p++;
302         }
303         if (len) {
304                 mask_to_set &= BITMAP_LAST_WORD_MASK(size);
305                 *p |= mask_to_set;
306         }
307 }
308 EXPORT_SYMBOL(bitmap_set);
309 
310 void bitmap_clear(unsigned long *map, unsigned int start, int len)
311 {
312         unsigned long *p = map + BIT_WORD(start);
313         const unsigned int size = start + len;
314         int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
315         unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
316 
317         while (len - bits_to_clear >= 0) {
318                 *p &= ~mask_to_clear;
319                 len -= bits_to_clear;
320                 bits_to_clear = BITS_PER_LONG;
321                 mask_to_clear = ~0UL;
322                 p++;
323         }
324         if (len) {
325                 mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
326                 *p &= ~mask_to_clear;
327         }
328 }
329 EXPORT_SYMBOL(bitmap_clear);
330 
331 /**
332  * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
333  * @map: The address to base the search on
334  * @size: The bitmap size in bits
335  * @start: The bitnumber to start searching at
336  * @nr: The number of zeroed bits we're looking for
337  * @align_mask: Alignment mask for zero area
338  * @align_offset: Alignment offset for zero area.
339  *
340  * The @align_mask should be one less than a power of 2; the effect is that
341  * the bit offset of all zero areas this function finds plus @align_offset
342  * is multiple of that power of 2.
343  */
344 unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
345                                              unsigned long size,
346                                              unsigned long start,
347                                              unsigned int nr,
348                                              unsigned long align_mask,
349                                              unsigned long align_offset)
350 {
351         unsigned long index, end, i;
352 again:
353         index = find_next_zero_bit(map, size, start);
354 
355         /* Align allocation */
356         index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
357 
358         end = index + nr;
359         if (end > size)
360                 return end;
361         i = find_next_bit(map, end, index);
362         if (i < end) {
363                 start = i + 1;
364                 goto again;
365         }
366         return index;
367 }
368 EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
369 
370 /*
371  * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
372  * second version by Paul Jackson, third by Joe Korty.
373  */
374 
375 #define CHUNKSZ                         32
376 #define nbits_to_hold_value(val)        fls(val)
377 #define BASEDEC 10              /* fancier cpuset lists input in decimal */
378 
379 /**
380  * bitmap_scnprintf - convert bitmap to an ASCII hex string.
381  * @buf: byte buffer into which string is placed
382  * @buflen: reserved size of @buf, in bytes
383  * @maskp: pointer to bitmap to convert
384  * @nmaskbits: size of bitmap, in bits
385  *
386  * Exactly @nmaskbits bits are displayed.  Hex digits are grouped into
387  * comma-separated sets of eight digits per set.  Returns the number of
388  * characters which were written to *buf, excluding the trailing \0.
389  */
390 int bitmap_scnprintf(char *buf, unsigned int buflen,
391         const unsigned long *maskp, int nmaskbits)
392 {
393         int i, word, bit, len = 0;
394         unsigned long val;
395         const char *sep = "";
396         int chunksz;
397         u32 chunkmask;
398 
399         chunksz = nmaskbits & (CHUNKSZ - 1);
400         if (chunksz == 0)
401                 chunksz = CHUNKSZ;
402 
403         i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ;
404         for (; i >= 0; i -= CHUNKSZ) {
405                 chunkmask = ((1ULL << chunksz) - 1);
406                 word = i / BITS_PER_LONG;
407                 bit = i % BITS_PER_LONG;
408                 val = (maskp[word] >> bit) & chunkmask;
409                 len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep,
410                         (chunksz+3)/4, val);
411                 chunksz = CHUNKSZ;
412                 sep = ",";
413         }
414         return len;
415 }
416 EXPORT_SYMBOL(bitmap_scnprintf);
417 
418 /**
419  * __bitmap_parse - convert an ASCII hex string into a bitmap.
420  * @buf: pointer to buffer containing string.
421  * @buflen: buffer size in bytes.  If string is smaller than this
422  *    then it must be terminated with a \0.
423  * @is_user: location of buffer, 0 indicates kernel space
424  * @maskp: pointer to bitmap array that will contain result.
425  * @nmaskbits: size of bitmap, in bits.
426  *
427  * Commas group hex digits into chunks.  Each chunk defines exactly 32
428  * bits of the resultant bitmask.  No chunk may specify a value larger
429  * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
430  * then leading 0-bits are prepended.  %-EINVAL is returned for illegal
431  * characters and for grouping errors such as "1,,5", ",44", "," and "".
432  * Leading and trailing whitespace accepted, but not embedded whitespace.
433  */
434 int __bitmap_parse(const char *buf, unsigned int buflen,
435                 int is_user, unsigned long *maskp,
436                 int nmaskbits)
437 {
438         int c, old_c, totaldigits, ndigits, nchunks, nbits;
439         u32 chunk;
440         const char __user __force *ubuf = (const char __user __force *)buf;
441 
442         bitmap_zero(maskp, nmaskbits);
443 
444         nchunks = nbits = totaldigits = c = 0;
445         do {
446                 chunk = ndigits = 0;
447 
448                 /* Get the next chunk of the bitmap */
449                 while (buflen) {
450                         old_c = c;
451                         if (is_user) {
452                                 if (__get_user(c, ubuf++))
453                                         return -EFAULT;
454                         }
455                         else
456                                 c = *buf++;
457                         buflen--;
458                         if (isspace(c))
459                                 continue;
460 
461                         /*
462                          * If the last character was a space and the current
463                          * character isn't '\0', we've got embedded whitespace.
464                          * This is a no-no, so throw an error.
465                          */
466                         if (totaldigits && c && isspace(old_c))
467                                 return -EINVAL;
468 
469                         /* A '\0' or a ',' signal the end of the chunk */
470                         if (c == '\0' || c == ',')
471                                 break;
472 
473                         if (!isxdigit(c))
474                                 return -EINVAL;
475 
476                         /*
477                          * Make sure there are at least 4 free bits in 'chunk'.
478                          * If not, this hexdigit will overflow 'chunk', so
479                          * throw an error.
480                          */
481                         if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
482                                 return -EOVERFLOW;
483 
484                         chunk = (chunk << 4) | hex_to_bin(c);
485                         ndigits++; totaldigits++;
486                 }
487                 if (ndigits == 0)
488                         return -EINVAL;
489                 if (nchunks == 0 && chunk == 0)
490                         continue;
491 
492                 __bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
493                 *maskp |= chunk;
494                 nchunks++;
495                 nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
496                 if (nbits > nmaskbits)
497                         return -EOVERFLOW;
498         } while (buflen && c == ',');
499 
500         return 0;
501 }
502 EXPORT_SYMBOL(__bitmap_parse);
503 
504 /**
505  * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
506  *
507  * @ubuf: pointer to user buffer containing string.
508  * @ulen: buffer size in bytes.  If string is smaller than this
509  *    then it must be terminated with a \0.
510  * @maskp: pointer to bitmap array that will contain result.
511  * @nmaskbits: size of bitmap, in bits.
512  *
513  * Wrapper for __bitmap_parse(), providing it with user buffer.
514  *
515  * We cannot have this as an inline function in bitmap.h because it needs
516  * linux/uaccess.h to get the access_ok() declaration and this causes
517  * cyclic dependencies.
518  */
519 int bitmap_parse_user(const char __user *ubuf,
520                         unsigned int ulen, unsigned long *maskp,
521                         int nmaskbits)
522 {
523         if (!access_ok(VERIFY_READ, ubuf, ulen))
524                 return -EFAULT;
525         return __bitmap_parse((const char __force *)ubuf,
526                                 ulen, 1, maskp, nmaskbits);
527 
528 }
529 EXPORT_SYMBOL(bitmap_parse_user);
530 
531 /*
532  * bscnl_emit(buf, buflen, rbot, rtop, bp)
533  *
534  * Helper routine for bitmap_scnlistprintf().  Write decimal number
535  * or range to buf, suppressing output past buf+buflen, with optional
536  * comma-prefix.  Return len of what was written to *buf, excluding the
537  * trailing \0.
538  */
539 static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
540 {
541         if (len > 0)
542                 len += scnprintf(buf + len, buflen - len, ",");
543         if (rbot == rtop)
544                 len += scnprintf(buf + len, buflen - len, "%d", rbot);
545         else
546                 len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
547         return len;
548 }
549 
550 /**
551  * bitmap_scnlistprintf - convert bitmap to list format ASCII string
552  * @buf: byte buffer into which string is placed
553  * @buflen: reserved size of @buf, in bytes
554  * @maskp: pointer to bitmap to convert
555  * @nmaskbits: size of bitmap, in bits
556  *
557  * Output format is a comma-separated list of decimal numbers and
558  * ranges.  Consecutively set bits are shown as two hyphen-separated
559  * decimal numbers, the smallest and largest bit numbers set in
560  * the range.  Output format is compatible with the format
561  * accepted as input by bitmap_parselist().
562  *
563  * The return value is the number of characters which were written to *buf
564  * excluding the trailing '\0', as per ISO C99's scnprintf.
565  */
566 int bitmap_scnlistprintf(char *buf, unsigned int buflen,
567         const unsigned long *maskp, int nmaskbits)
568 {
569         int len = 0;
570         /* current bit is 'cur', most recently seen range is [rbot, rtop] */
571         int cur, rbot, rtop;
572 
573         if (buflen == 0)
574                 return 0;
575         buf[0] = 0;
576 
577         rbot = cur = find_first_bit(maskp, nmaskbits);
578         while (cur < nmaskbits) {
579                 rtop = cur;
580                 cur = find_next_bit(maskp, nmaskbits, cur+1);
581                 if (cur >= nmaskbits || cur > rtop + 1) {
582                         len = bscnl_emit(buf, buflen, rbot, rtop, len);
583                         rbot = cur;
584                 }
585         }
586         return len;
587 }
588 EXPORT_SYMBOL(bitmap_scnlistprintf);
589 
590 /**
591  * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
592  * @list: indicates whether the bitmap must be list
593  * @buf: page aligned buffer into which string is placed
594  * @maskp: pointer to bitmap to convert
595  * @nmaskbits: size of bitmap, in bits
596  *
597  * Output format is a comma-separated list of decimal numbers and
598  * ranges if list is specified or hex digits grouped into comma-separated
599  * sets of 8 digits/set. Returns the number of characters written to buf.
600  */
601 int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
602                             int nmaskbits)
603 {
604         ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf - 2;
605         int n = 0;
606 
607         if (len > 1) {
608                 n = list ? bitmap_scnlistprintf(buf, len, maskp, nmaskbits) :
609                            bitmap_scnprintf(buf, len, maskp, nmaskbits);
610                 buf[n++] = '\n';
611                 buf[n] = '\0';
612         }
613         return n;
614 }
615 EXPORT_SYMBOL(bitmap_print_to_pagebuf);
616 
617 /**
618  * __bitmap_parselist - convert list format ASCII string to bitmap
619  * @buf: read nul-terminated user string from this buffer
620  * @buflen: buffer size in bytes.  If string is smaller than this
621  *    then it must be terminated with a \0.
622  * @is_user: location of buffer, 0 indicates kernel space
623  * @maskp: write resulting mask here
624  * @nmaskbits: number of bits in mask to be written
625  *
626  * Input format is a comma-separated list of decimal numbers and
627  * ranges.  Consecutively set bits are shown as two hyphen-separated
628  * decimal numbers, the smallest and largest bit numbers set in
629  * the range.
630  *
631  * Returns 0 on success, -errno on invalid input strings.
632  * Error values:
633  *    %-EINVAL: second number in range smaller than first
634  *    %-EINVAL: invalid character in string
635  *    %-ERANGE: bit number specified too large for mask
636  */
637 static int __bitmap_parselist(const char *buf, unsigned int buflen,
638                 int is_user, unsigned long *maskp,
639                 int nmaskbits)
640 {
641         unsigned a, b;
642         int c, old_c, totaldigits;
643         const char __user __force *ubuf = (const char __user __force *)buf;
644         int exp_digit, in_range;
645 
646         totaldigits = c = 0;
647         bitmap_zero(maskp, nmaskbits);
648         do {
649                 exp_digit = 1;
650                 in_range = 0;
651                 a = b = 0;
652 
653                 /* Get the next cpu# or a range of cpu#'s */
654                 while (buflen) {
655                         old_c = c;
656                         if (is_user) {
657                                 if (__get_user(c, ubuf++))
658                                         return -EFAULT;
659                         } else
660                                 c = *buf++;
661                         buflen--;
662                         if (isspace(c))
663                                 continue;
664 
665                         /*
666                          * If the last character was a space and the current
667                          * character isn't '\0', we've got embedded whitespace.
668                          * This is a no-no, so throw an error.
669                          */
670                         if (totaldigits && c && isspace(old_c))
671                                 return -EINVAL;
672 
673                         /* A '\0' or a ',' signal the end of a cpu# or range */
674                         if (c == '\0' || c == ',')
675                                 break;
676 
677                         if (c == '-') {
678                                 if (exp_digit || in_range)
679                                         return -EINVAL;
680                                 b = 0;
681                                 in_range = 1;
682                                 exp_digit = 1;
683                                 continue;
684                         }
685 
686                         if (!isdigit(c))
687                                 return -EINVAL;
688 
689                         b = b * 10 + (c - '');
690                         if (!in_range)
691                                 a = b;
692                         exp_digit = 0;
693                         totaldigits++;
694                 }
695                 if (!(a <= b))
696                         return -EINVAL;
697                 if (b >= nmaskbits)
698                         return -ERANGE;
699                 while (a <= b) {
700                         set_bit(a, maskp);
701                         a++;
702                 }
703         } while (buflen && c == ',');
704         return 0;
705 }
706 
707 int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
708 {
709         char *nl  = strchrnul(bp, '\n');
710         int len = nl - bp;
711 
712         return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
713 }
714 EXPORT_SYMBOL(bitmap_parselist);
715 
716 
717 /**
718  * bitmap_parselist_user()
719  *
720  * @ubuf: pointer to user buffer containing string.
721  * @ulen: buffer size in bytes.  If string is smaller than this
722  *    then it must be terminated with a \0.
723  * @maskp: pointer to bitmap array that will contain result.
724  * @nmaskbits: size of bitmap, in bits.
725  *
726  * Wrapper for bitmap_parselist(), providing it with user buffer.
727  *
728  * We cannot have this as an inline function in bitmap.h because it needs
729  * linux/uaccess.h to get the access_ok() declaration and this causes
730  * cyclic dependencies.
731  */
732 int bitmap_parselist_user(const char __user *ubuf,
733                         unsigned int ulen, unsigned long *maskp,
734                         int nmaskbits)
735 {
736         if (!access_ok(VERIFY_READ, ubuf, ulen))
737                 return -EFAULT;
738         return __bitmap_parselist((const char __force *)ubuf,
739                                         ulen, 1, maskp, nmaskbits);
740 }
741 EXPORT_SYMBOL(bitmap_parselist_user);
742 
743 
744 /**
745  * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
746  *      @buf: pointer to a bitmap
747  *      @pos: a bit position in @buf (0 <= @pos < @bits)
748  *      @bits: number of valid bit positions in @buf
749  *
750  * Map the bit at position @pos in @buf (of length @bits) to the
751  * ordinal of which set bit it is.  If it is not set or if @pos
752  * is not a valid bit position, map to -1.
753  *
754  * If for example, just bits 4 through 7 are set in @buf, then @pos
755  * values 4 through 7 will get mapped to 0 through 3, respectively,
756  * and other @pos values will get mapped to -1.  When @pos value 7
757  * gets mapped to (returns) @ord value 3 in this example, that means
758  * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
759  *
760  * The bit positions 0 through @bits are valid positions in @buf.
761  */
762 static int bitmap_pos_to_ord(const unsigned long *buf, int pos, int bits)
763 {
764         int i, ord;
765 
766         if (pos < 0 || pos >= bits || !test_bit(pos, buf))
767                 return -1;
768 
769         i = find_first_bit(buf, bits);
770         ord = 0;
771         while (i < pos) {
772                 i = find_next_bit(buf, bits, i + 1);
773                 ord++;
774         }
775         BUG_ON(i != pos);
776 
777         return ord;
778 }
779 
780 /**
781  * bitmap_ord_to_pos - find position of n-th set bit in bitmap
782  *      @buf: pointer to bitmap
783  *      @ord: ordinal bit position (n-th set bit, n >= 0)
784  *      @bits: number of valid bit positions in @buf
785  *
786  * Map the ordinal offset of bit @ord in @buf to its position in @buf.
787  * Value of @ord should be in range 0 <= @ord < weight(buf), else
788  * results are undefined.
789  *
790  * If for example, just bits 4 through 7 are set in @buf, then @ord
791  * values 0 through 3 will get mapped to 4 through 7, respectively,
792  * and all other @ord values return undefined values.  When @ord value 3
793  * gets mapped to (returns) @pos value 7 in this example, that means
794  * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
795  *
796  * The bit positions 0 through @bits are valid positions in @buf.
797  */
798 int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
799 {
800         int pos = 0;
801 
802         if (ord >= 0 && ord < bits) {
803                 int i;
804 
805                 for (i = find_first_bit(buf, bits);
806                      i < bits && ord > 0;
807                      i = find_next_bit(buf, bits, i + 1))
808                         ord--;
809                 if (i < bits && ord == 0)
810                         pos = i;
811         }
812 
813         return pos;
814 }
815 
816 /**
817  * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
818  *      @dst: remapped result
819  *      @src: subset to be remapped
820  *      @old: defines domain of map
821  *      @new: defines range of map
822  *      @bits: number of bits in each of these bitmaps
823  *
824  * Let @old and @new define a mapping of bit positions, such that
825  * whatever position is held by the n-th set bit in @old is mapped
826  * to the n-th set bit in @new.  In the more general case, allowing
827  * for the possibility that the weight 'w' of @new is less than the
828  * weight of @old, map the position of the n-th set bit in @old to
829  * the position of the m-th set bit in @new, where m == n % w.
830  *
831  * If either of the @old and @new bitmaps are empty, or if @src and
832  * @dst point to the same location, then this routine copies @src
833  * to @dst.
834  *
835  * The positions of unset bits in @old are mapped to themselves
836  * (the identify map).
837  *
838  * Apply the above specified mapping to @src, placing the result in
839  * @dst, clearing any bits previously set in @dst.
840  *
841  * For example, lets say that @old has bits 4 through 7 set, and
842  * @new has bits 12 through 15 set.  This defines the mapping of bit
843  * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
844  * bit positions unchanged.  So if say @src comes into this routine
845  * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
846  * 13 and 15 set.
847  */
848 void bitmap_remap(unsigned long *dst, const unsigned long *src,
849                 const unsigned long *old, const unsigned long *new,
850                 int bits)
851 {
852         int oldbit, w;
853 
854         if (dst == src)         /* following doesn't handle inplace remaps */
855                 return;
856         bitmap_zero(dst, bits);
857 
858         w = bitmap_weight(new, bits);
859         for_each_set_bit(oldbit, src, bits) {
860                 int n = bitmap_pos_to_ord(old, oldbit, bits);
861 
862                 if (n < 0 || w == 0)
863                         set_bit(oldbit, dst);   /* identity map */
864                 else
865                         set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);
866         }
867 }
868 EXPORT_SYMBOL(bitmap_remap);
869 
870 /**
871  * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
872  *      @oldbit: bit position to be mapped
873  *      @old: defines domain of map
874  *      @new: defines range of map
875  *      @bits: number of bits in each of these bitmaps
876  *
877  * Let @old and @new define a mapping of bit positions, such that
878  * whatever position is held by the n-th set bit in @old is mapped
879  * to the n-th set bit in @new.  In the more general case, allowing
880  * for the possibility that the weight 'w' of @new is less than the
881  * weight of @old, map the position of the n-th set bit in @old to
882  * the position of the m-th set bit in @new, where m == n % w.
883  *
884  * The positions of unset bits in @old are mapped to themselves
885  * (the identify map).
886  *
887  * Apply the above specified mapping to bit position @oldbit, returning
888  * the new bit position.
889  *
890  * For example, lets say that @old has bits 4 through 7 set, and
891  * @new has bits 12 through 15 set.  This defines the mapping of bit
892  * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
893  * bit positions unchanged.  So if say @oldbit is 5, then this routine
894  * returns 13.
895  */
896 int bitmap_bitremap(int oldbit, const unsigned long *old,
897                                 const unsigned long *new, int bits)
898 {
899         int w = bitmap_weight(new, bits);
900         int n = bitmap_pos_to_ord(old, oldbit, bits);
901         if (n < 0 || w == 0)
902                 return oldbit;
903         else
904                 return bitmap_ord_to_pos(new, n % w, bits);
905 }
906 EXPORT_SYMBOL(bitmap_bitremap);
907 
908 /**
909  * bitmap_onto - translate one bitmap relative to another
910  *      @dst: resulting translated bitmap
911  *      @orig: original untranslated bitmap
912  *      @relmap: bitmap relative to which translated
913  *      @bits: number of bits in each of these bitmaps
914  *
915  * Set the n-th bit of @dst iff there exists some m such that the
916  * n-th bit of @relmap is set, the m-th bit of @orig is set, and
917  * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
918  * (If you understood the previous sentence the first time your
919  * read it, you're overqualified for your current job.)
920  *
921  * In other words, @orig is mapped onto (surjectively) @dst,
922  * using the map { <n, m> | the n-th bit of @relmap is the
923  * m-th set bit of @relmap }.
924  *
925  * Any set bits in @orig above bit number W, where W is the
926  * weight of (number of set bits in) @relmap are mapped nowhere.
927  * In particular, if for all bits m set in @orig, m >= W, then
928  * @dst will end up empty.  In situations where the possibility
929  * of such an empty result is not desired, one way to avoid it is
930  * to use the bitmap_fold() operator, below, to first fold the
931  * @orig bitmap over itself so that all its set bits x are in the
932  * range 0 <= x < W.  The bitmap_fold() operator does this by
933  * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
934  *
935  * Example [1] for bitmap_onto():
936  *  Let's say @relmap has bits 30-39 set, and @orig has bits
937  *  1, 3, 5, 7, 9 and 11 set.  Then on return from this routine,
938  *  @dst will have bits 31, 33, 35, 37 and 39 set.
939  *
940  *  When bit 0 is set in @orig, it means turn on the bit in
941  *  @dst corresponding to whatever is the first bit (if any)
942  *  that is turned on in @relmap.  Since bit 0 was off in the
943  *  above example, we leave off that bit (bit 30) in @dst.
944  *
945  *  When bit 1 is set in @orig (as in the above example), it
946  *  means turn on the bit in @dst corresponding to whatever
947  *  is the second bit that is turned on in @relmap.  The second
948  *  bit in @relmap that was turned on in the above example was
949  *  bit 31, so we turned on bit 31 in @dst.
950  *
951  *  Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
952  *  because they were the 4th, 6th, 8th and 10th set bits
953  *  set in @relmap, and the 4th, 6th, 8th and 10th bits of
954  *  @orig (i.e. bits 3, 5, 7 and 9) were also set.
955  *
956  *  When bit 11 is set in @orig, it means turn on the bit in
957  *  @dst corresponding to whatever is the twelfth bit that is
958  *  turned on in @relmap.  In the above example, there were
959  *  only ten bits turned on in @relmap (30..39), so that bit
960  *  11 was set in @orig had no affect on @dst.
961  *
962  * Example [2] for bitmap_fold() + bitmap_onto():
963  *  Let's say @relmap has these ten bits set:
964  *              40 41 42 43 45 48 53 61 74 95
965  *  (for the curious, that's 40 plus the first ten terms of the
966  *  Fibonacci sequence.)
967  *
968  *  Further lets say we use the following code, invoking
969  *  bitmap_fold() then bitmap_onto, as suggested above to
970  *  avoid the possibility of an empty @dst result:
971  *
972  *      unsigned long *tmp;     // a temporary bitmap's bits
973  *
974  *      bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
975  *      bitmap_onto(dst, tmp, relmap, bits);
976  *
977  *  Then this table shows what various values of @dst would be, for
978  *  various @orig's.  I list the zero-based positions of each set bit.
979  *  The tmp column shows the intermediate result, as computed by
980  *  using bitmap_fold() to fold the @orig bitmap modulo ten
981  *  (the weight of @relmap).
982  *
983  *      @orig           tmp            @dst
984  *      0                0             40
985  *      1                1             41
986  *      9                9             95
987  *      10               0             40 (*)
988  *      1 3 5 7          1 3 5 7       41 43 48 61
989  *      0 1 2 3 4        0 1 2 3 4     40 41 42 43 45
990  *      0 9 18 27        0 9 8 7       40 61 74 95
991  *      0 10 20 30       0             40
992  *      0 11 22 33       0 1 2 3       40 41 42 43
993  *      0 12 24 36       0 2 4 6       40 42 45 53
994  *      78 102 211       1 2 8         41 42 74 (*)
995  *
996  * (*) For these marked lines, if we hadn't first done bitmap_fold()
997  *     into tmp, then the @dst result would have been empty.
998  *
999  * If either of @orig or @relmap is empty (no set bits), then @dst
1000  * will be returned empty.
1001  *
1002  * If (as explained above) the only set bits in @orig are in positions
1003  * m where m >= W, (where W is the weight of @relmap) then @dst will
1004  * once again be returned empty.
1005  *
1006  * All bits in @dst not set by the above rule are cleared.
1007  */
1008 void bitmap_onto(unsigned long *dst, const unsigned long *orig,
1009                         const unsigned long *relmap, int bits)
1010 {
1011         int n, m;               /* same meaning as in above comment */
1012 
1013         if (dst == orig)        /* following doesn't handle inplace mappings */
1014                 return;
1015         bitmap_zero(dst, bits);
1016 
1017         /*
1018          * The following code is a more efficient, but less
1019          * obvious, equivalent to the loop:
1020          *      for (m = 0; m < bitmap_weight(relmap, bits); m++) {
1021          *              n = bitmap_ord_to_pos(orig, m, bits);
1022          *              if (test_bit(m, orig))
1023          *                      set_bit(n, dst);
1024          *      }
1025          */
1026 
1027         m = 0;
1028         for_each_set_bit(n, relmap, bits) {
1029                 /* m == bitmap_pos_to_ord(relmap, n, bits) */
1030                 if (test_bit(m, orig))
1031                         set_bit(n, dst);
1032                 m++;
1033         }
1034 }
1035 EXPORT_SYMBOL(bitmap_onto);
1036 
1037 /**
1038  * bitmap_fold - fold larger bitmap into smaller, modulo specified size
1039  *      @dst: resulting smaller bitmap
1040  *      @orig: original larger bitmap
1041  *      @sz: specified size
1042  *      @bits: number of bits in each of these bitmaps
1043  *
1044  * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
1045  * Clear all other bits in @dst.  See further the comment and
1046  * Example [2] for bitmap_onto() for why and how to use this.
1047  */
1048 void bitmap_fold(unsigned long *dst, const unsigned long *orig,
1049                         int sz, int bits)
1050 {
1051         int oldbit;
1052 
1053         if (dst == orig)        /* following doesn't handle inplace mappings */
1054                 return;
1055         bitmap_zero(dst, bits);
1056 
1057         for_each_set_bit(oldbit, orig, bits)
1058                 set_bit(oldbit % sz, dst);
1059 }
1060 EXPORT_SYMBOL(bitmap_fold);
1061 
1062 /*
1063  * Common code for bitmap_*_region() routines.
1064  *      bitmap: array of unsigned longs corresponding to the bitmap
1065  *      pos: the beginning of the region
1066  *      order: region size (log base 2 of number of bits)
1067  *      reg_op: operation(s) to perform on that region of bitmap
1068  *
1069  * Can set, verify and/or release a region of bits in a bitmap,
1070  * depending on which combination of REG_OP_* flag bits is set.
1071  *
1072  * A region of a bitmap is a sequence of bits in the bitmap, of
1073  * some size '1 << order' (a power of two), aligned to that same
1074  * '1 << order' power of two.
1075  *
1076  * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
1077  * Returns 0 in all other cases and reg_ops.
1078  */
1079 
1080 enum {
1081         REG_OP_ISFREE,          /* true if region is all zero bits */
1082         REG_OP_ALLOC,           /* set all bits in region */
1083         REG_OP_RELEASE,         /* clear all bits in region */
1084 };
1085 
1086 static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
1087 {
1088         int nbits_reg;          /* number of bits in region */
1089         int index;              /* index first long of region in bitmap */
1090         int offset;             /* bit offset region in bitmap[index] */
1091         int nlongs_reg;         /* num longs spanned by region in bitmap */
1092         int nbitsinlong;        /* num bits of region in each spanned long */
1093         unsigned long mask;     /* bitmask for one long of region */
1094         int i;                  /* scans bitmap by longs */
1095         int ret = 0;            /* return value */
1096 
1097         /*
1098          * Either nlongs_reg == 1 (for small orders that fit in one long)
1099          * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
1100          */
1101         nbits_reg = 1 << order;
1102         index = pos / BITS_PER_LONG;
1103         offset = pos - (index * BITS_PER_LONG);
1104         nlongs_reg = BITS_TO_LONGS(nbits_reg);
1105         nbitsinlong = min(nbits_reg,  BITS_PER_LONG);
1106 
1107         /*
1108          * Can't do "mask = (1UL << nbitsinlong) - 1", as that
1109          * overflows if nbitsinlong == BITS_PER_LONG.
1110          */
1111         mask = (1UL << (nbitsinlong - 1));
1112         mask += mask - 1;
1113         mask <<= offset;
1114 
1115         switch (reg_op) {
1116         case REG_OP_ISFREE:
1117                 for (i = 0; i < nlongs_reg; i++) {
1118                         if (bitmap[index + i] & mask)
1119                                 goto done;
1120                 }
1121                 ret = 1;        /* all bits in region free (zero) */
1122                 break;
1123 
1124         case REG_OP_ALLOC:
1125                 for (i = 0; i < nlongs_reg; i++)
1126                         bitmap[index + i] |= mask;
1127                 break;
1128 
1129         case REG_OP_RELEASE:
1130                 for (i = 0; i < nlongs_reg; i++)
1131                         bitmap[index + i] &= ~mask;
1132                 break;
1133         }
1134 done:
1135         return ret;
1136 }
1137 
1138 /**
1139  * bitmap_find_free_region - find a contiguous aligned mem region
1140  *      @bitmap: array of unsigned longs corresponding to the bitmap
1141  *      @bits: number of bits in the bitmap
1142  *      @order: region size (log base 2 of number of bits) to find
1143  *
1144  * Find a region of free (zero) bits in a @bitmap of @bits bits and
1145  * allocate them (set them to one).  Only consider regions of length
1146  * a power (@order) of two, aligned to that power of two, which
1147  * makes the search algorithm much faster.
1148  *
1149  * Return the bit offset in bitmap of the allocated region,
1150  * or -errno on failure.
1151  */
1152 int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
1153 {
1154         unsigned int pos, end;          /* scans bitmap by regions of size order */
1155 
1156         for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
1157                 if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1158                         continue;
1159                 __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1160                 return pos;
1161         }
1162         return -ENOMEM;
1163 }
1164 EXPORT_SYMBOL(bitmap_find_free_region);
1165 
1166 /**
1167  * bitmap_release_region - release allocated bitmap region
1168  *      @bitmap: array of unsigned longs corresponding to the bitmap
1169  *      @pos: beginning of bit region to release
1170  *      @order: region size (log base 2 of number of bits) to release
1171  *
1172  * This is the complement to __bitmap_find_free_region() and releases
1173  * the found region (by clearing it in the bitmap).
1174  *
1175  * No return value.
1176  */
1177 void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
1178 {
1179         __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1180 }
1181 EXPORT_SYMBOL(bitmap_release_region);
1182 
1183 /**
1184  * bitmap_allocate_region - allocate bitmap region
1185  *      @bitmap: array of unsigned longs corresponding to the bitmap
1186  *      @pos: beginning of bit region to allocate
1187  *      @order: region size (log base 2 of number of bits) to allocate
1188  *
1189  * Allocate (set bits in) a specified region of a bitmap.
1190  *
1191  * Return 0 on success, or %-EBUSY if specified region wasn't
1192  * free (not all bits were zero).
1193  */
1194 int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
1195 {
1196         if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
1197                 return -EBUSY;
1198         return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
1199 }
1200 EXPORT_SYMBOL(bitmap_allocate_region);
1201 
1202 /**
1203  * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
1204  * @dst:   destination buffer
1205  * @src:   bitmap to copy
1206  * @nbits: number of bits in the bitmap
1207  *
1208  * Require nbits % BITS_PER_LONG == 0.
1209  */
1210 void bitmap_copy_le(void *dst, const unsigned long *src, int nbits)
1211 {
1212         unsigned long *d = dst;
1213         int i;
1214 
1215         for (i = 0; i < nbits/BITS_PER_LONG; i++) {
1216                 if (BITS_PER_LONG == 64)
1217                         d[i] = cpu_to_le64(src[i]);
1218                 else
1219                         d[i] = cpu_to_le32(src[i]);
1220         }
1221 }
1222 EXPORT_SYMBOL(bitmap_copy_le);
1223 

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