Root/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
43int __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}
56EXPORT_SYMBOL(__bitmap_empty);
57
58int __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}
71EXPORT_SYMBOL(__bitmap_full);
72
73int __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}
87EXPORT_SYMBOL(__bitmap_equal);
88
89void __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}
98EXPORT_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 */
111void __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}
141EXPORT_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
156void __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}
182EXPORT_SYMBOL(__bitmap_shift_left);
183
184int __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}
195EXPORT_SYMBOL(__bitmap_and);
196
197void __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}
206EXPORT_SYMBOL(__bitmap_or);
207
208void __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}
217EXPORT_SYMBOL(__bitmap_xor);
218
219int __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}
230EXPORT_SYMBOL(__bitmap_andnot);
231
232int __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}
245EXPORT_SYMBOL(__bitmap_intersects);
246
247int __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}
260EXPORT_SYMBOL(__bitmap_subset);
261
262int __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}
274EXPORT_SYMBOL(__bitmap_weight);
275
276void 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}
295EXPORT_SYMBOL(bitmap_set);
296
297void 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}
316EXPORT_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 */
330unsigned 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;
337again:
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}
353EXPORT_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 */
375int 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}
401EXPORT_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 */
419int __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}
487EXPORT_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 */
504int 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}
514EXPORT_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 */
524static 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 */
551int 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}
573EXPORT_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 */
595static 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 - '0');
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
665int 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}
677EXPORT_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 */
695int 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}
704EXPORT_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 */
725static 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 */
761int 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 */
811void 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}
831EXPORT_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 */
859int 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}
869EXPORT_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 */
971void 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}
998EXPORT_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 */
1011void 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}
1023EXPORT_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
1043enum {
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
1049static 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    }
1097done:
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 */
1115int 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}
1127EXPORT_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 */
1140void bitmap_release_region(unsigned long *bitmap, int pos, int order)
1141{
1142    __reg_op(bitmap, pos, order, REG_OP_RELEASE);
1143}
1144EXPORT_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 */
1157int 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}
1164EXPORT_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 */
1174void 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}
1186EXPORT_SYMBOL(bitmap_copy_le);
1187

Archive Download this file



interactive