bitmap.c 36.1 KB
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/*
 * lib/bitmap.c
 * Helper functions for bitmap.h.
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 */
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#include <linux/export.h>
#include <linux/thread_info.h>
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#include <linux/ctype.h>
#include <linux/errno.h>
#include <linux/bitmap.h>
#include <linux/bitops.h>
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#include <linux/bug.h>
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#include <asm/page.h>
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#include <asm/uaccess.h>

/*
 * bitmaps provide an array of bits, implemented using an an
 * array of unsigned longs.  The number of valid bits in a
 * given bitmap does _not_ need to be an exact multiple of
 * BITS_PER_LONG.
 *
 * The possible unused bits in the last, partially used word
 * of a bitmap are 'don't care'.  The implementation makes
 * no particular effort to keep them zero.  It ensures that
 * their value will not affect the results of any operation.
 * The bitmap operations that return Boolean (bitmap_empty,
 * for example) or scalar (bitmap_weight, for example) results
 * carefully filter out these unused bits from impacting their
 * results.
 *
 * These operations actually hold to a slightly stronger rule:
 * if you don't input any bitmaps to these ops that have some
 * unused bits set, then they won't output any set unused bits
 * in output bitmaps.
 *
 * The byte ordering of bitmaps is more natural on little
 * endian architectures.  See the big-endian headers
 * include/asm-ppc64/bitops.h and include/asm-s390/bitops.h
 * for the best explanations of this ordering.
 */

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int __bitmap_empty(const unsigned long *bitmap, unsigned int bits)
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{
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	unsigned int k, lim = bits/BITS_PER_LONG;
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	for (k = 0; k < lim; ++k)
		if (bitmap[k])
			return 0;

	if (bits % BITS_PER_LONG)
		if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
			return 0;

	return 1;
}
EXPORT_SYMBOL(__bitmap_empty);

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int __bitmap_full(const unsigned long *bitmap, unsigned int bits)
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{
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	unsigned int k, lim = bits/BITS_PER_LONG;
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	for (k = 0; k < lim; ++k)
		if (~bitmap[k])
			return 0;

	if (bits % BITS_PER_LONG)
		if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits))
			return 0;

	return 1;
}
EXPORT_SYMBOL(__bitmap_full);

int __bitmap_equal(const unsigned long *bitmap1,
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		const unsigned long *bitmap2, unsigned int bits)
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{
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	unsigned int k, lim = bits/BITS_PER_LONG;
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	for (k = 0; k < lim; ++k)
		if (bitmap1[k] != bitmap2[k])
			return 0;

	if (bits % BITS_PER_LONG)
		if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
			return 0;

	return 1;
}
EXPORT_SYMBOL(__bitmap_equal);

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void __bitmap_complement(unsigned long *dst, const unsigned long *src, unsigned int bits)
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{
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	unsigned int k, lim = bits/BITS_PER_LONG;
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	for (k = 0; k < lim; ++k)
		dst[k] = ~src[k];

	if (bits % BITS_PER_LONG)
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		dst[k] = ~src[k];
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}
EXPORT_SYMBOL(__bitmap_complement);

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/**
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 * __bitmap_shift_right - logical right shift of the bits in a bitmap
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 *   @dst : destination bitmap
 *   @src : source bitmap
 *   @shift : shift by this many bits
 *   @bits : bitmap size, in bits
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 *
 * Shifting right (dividing) means moving bits in the MS -> LS bit
 * direction.  Zeros are fed into the vacated MS positions and the
 * LS bits shifted off the bottom are lost.
 */
void __bitmap_shift_right(unsigned long *dst,
			const unsigned long *src, int shift, int bits)
{
	int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
	int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
	unsigned long mask = (1UL << left) - 1;
	for (k = 0; off + k < lim; ++k) {
		unsigned long upper, lower;

		/*
		 * If shift is not word aligned, take lower rem bits of
		 * word above and make them the top rem bits of result.
		 */
		if (!rem || off + k + 1 >= lim)
			upper = 0;
		else {
			upper = src[off + k + 1];
			if (off + k + 1 == lim - 1 && left)
				upper &= mask;
		}
		lower = src[off + k];
		if (left && off + k == lim - 1)
			lower &= mask;
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		dst[k] = lower >> rem;
		if (rem)
			dst[k] |= upper << (BITS_PER_LONG - rem);
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		if (left && k == lim - 1)
			dst[k] &= mask;
	}
	if (off)
		memset(&dst[lim - off], 0, off*sizeof(unsigned long));
}
EXPORT_SYMBOL(__bitmap_shift_right);


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/**
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 * __bitmap_shift_left - logical left shift of the bits in a bitmap
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 *   @dst : destination bitmap
 *   @src : source bitmap
 *   @shift : shift by this many bits
 *   @bits : bitmap size, in bits
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 *
 * Shifting left (multiplying) means moving bits in the LS -> MS
 * direction.  Zeros are fed into the vacated LS bit positions
 * and those MS bits shifted off the top are lost.
 */

void __bitmap_shift_left(unsigned long *dst,
			const unsigned long *src, int shift, int bits)
{
	int k, lim = BITS_TO_LONGS(bits), left = bits % BITS_PER_LONG;
	int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
	for (k = lim - off - 1; k >= 0; --k) {
		unsigned long upper, lower;

		/*
		 * If shift is not word aligned, take upper rem bits of
		 * word below and make them the bottom rem bits of result.
		 */
		if (rem && k > 0)
			lower = src[k - 1];
		else
			lower = 0;
		upper = src[k];
		if (left && k == lim - 1)
			upper &= (1UL << left) - 1;
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		dst[k + off] = upper << rem;
		if (rem)
			dst[k + off] |= lower >> (BITS_PER_LONG - rem);
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		if (left && k + off == lim - 1)
			dst[k + off] &= (1UL << left) - 1;
	}
	if (off)
		memset(dst, 0, off*sizeof(unsigned long));
}
EXPORT_SYMBOL(__bitmap_shift_left);

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int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
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				const unsigned long *bitmap2, unsigned int bits)
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{
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	unsigned int k;
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	unsigned int lim = bits/BITS_PER_LONG;
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	unsigned long result = 0;
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	for (k = 0; k < lim; k++)
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		result |= (dst[k] = bitmap1[k] & bitmap2[k]);
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	if (bits % BITS_PER_LONG)
		result |= (dst[k] = bitmap1[k] & bitmap2[k] &
			   BITMAP_LAST_WORD_MASK(bits));
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	return result != 0;
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}
EXPORT_SYMBOL(__bitmap_and);

void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
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				const unsigned long *bitmap2, unsigned int bits)
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{
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	unsigned int k;
	unsigned int nr = BITS_TO_LONGS(bits);
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	for (k = 0; k < nr; k++)
		dst[k] = bitmap1[k] | bitmap2[k];
}
EXPORT_SYMBOL(__bitmap_or);

void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
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				const unsigned long *bitmap2, unsigned int bits)
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{
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	unsigned int k;
	unsigned int nr = BITS_TO_LONGS(bits);
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	for (k = 0; k < nr; k++)
		dst[k] = bitmap1[k] ^ bitmap2[k];
}
EXPORT_SYMBOL(__bitmap_xor);

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int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
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				const unsigned long *bitmap2, unsigned int bits)
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{
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	unsigned int k;
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	unsigned int lim = bits/BITS_PER_LONG;
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	unsigned long result = 0;
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	for (k = 0; k < lim; k++)
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		result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
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	if (bits % BITS_PER_LONG)
		result |= (dst[k] = bitmap1[k] & ~bitmap2[k] &
			   BITMAP_LAST_WORD_MASK(bits));
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	return result != 0;
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}
EXPORT_SYMBOL(__bitmap_andnot);

int __bitmap_intersects(const unsigned long *bitmap1,
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			const unsigned long *bitmap2, unsigned int bits)
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{
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	unsigned int k, lim = bits/BITS_PER_LONG;
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	for (k = 0; k < lim; ++k)
		if (bitmap1[k] & bitmap2[k])
			return 1;

	if (bits % BITS_PER_LONG)
		if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
			return 1;
	return 0;
}
EXPORT_SYMBOL(__bitmap_intersects);

int __bitmap_subset(const unsigned long *bitmap1,
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		    const unsigned long *bitmap2, unsigned int bits)
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{
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	unsigned int k, lim = bits/BITS_PER_LONG;
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	for (k = 0; k < lim; ++k)
		if (bitmap1[k] & ~bitmap2[k])
			return 0;

	if (bits % BITS_PER_LONG)
		if ((bitmap1[k] & ~bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits))
			return 0;
	return 1;
}
EXPORT_SYMBOL(__bitmap_subset);

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int __bitmap_weight(const unsigned long *bitmap, unsigned int bits)
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{
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	unsigned int k, lim = bits/BITS_PER_LONG;
	int w = 0;
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	for (k = 0; k < lim; k++)
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		w += hweight_long(bitmap[k]);
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	if (bits % BITS_PER_LONG)
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		w += hweight_long(bitmap[k] & BITMAP_LAST_WORD_MASK(bits));
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	return w;
}
EXPORT_SYMBOL(__bitmap_weight);

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void bitmap_set(unsigned long *map, unsigned int start, int len)
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{
	unsigned long *p = map + BIT_WORD(start);
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	const unsigned int size = start + len;
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	int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
	unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);

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	while (len - bits_to_set >= 0) {
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		*p |= mask_to_set;
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		len -= bits_to_set;
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		bits_to_set = BITS_PER_LONG;
		mask_to_set = ~0UL;
		p++;
	}
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	if (len) {
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		mask_to_set &= BITMAP_LAST_WORD_MASK(size);
		*p |= mask_to_set;
	}
}
EXPORT_SYMBOL(bitmap_set);

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void bitmap_clear(unsigned long *map, unsigned int start, int len)
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{
	unsigned long *p = map + BIT_WORD(start);
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	const unsigned int size = start + len;
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	int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
	unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);

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	while (len - bits_to_clear >= 0) {
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		*p &= ~mask_to_clear;
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		len -= bits_to_clear;
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		bits_to_clear = BITS_PER_LONG;
		mask_to_clear = ~0UL;
		p++;
	}
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	if (len) {
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		mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
		*p &= ~mask_to_clear;
	}
}
EXPORT_SYMBOL(bitmap_clear);

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/**
 * bitmap_find_next_zero_area_off - find a contiguous aligned zero area
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 * @map: The address to base the search on
 * @size: The bitmap size in bits
 * @start: The bitnumber to start searching at
 * @nr: The number of zeroed bits we're looking for
 * @align_mask: Alignment mask for zero area
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 * @align_offset: Alignment offset for zero area.
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 *
 * The @align_mask should be one less than a power of 2; the effect is that
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 * the bit offset of all zero areas this function finds plus @align_offset
 * is multiple of that power of 2.
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 */
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unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
					     unsigned long size,
					     unsigned long start,
					     unsigned int nr,
					     unsigned long align_mask,
					     unsigned long align_offset)
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{
	unsigned long index, end, i;
again:
	index = find_next_zero_bit(map, size, start);

	/* Align allocation */
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	index = __ALIGN_MASK(index + align_offset, align_mask) - align_offset;
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	end = index + nr;
	if (end > size)
		return end;
	i = find_next_bit(map, end, index);
	if (i < end) {
		start = i + 1;
		goto again;
	}
	return index;
}
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EXPORT_SYMBOL(bitmap_find_next_zero_area_off);
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/*
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 * Bitmap printing & parsing functions: first version by Nadia Yvette Chambers,
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 * second version by Paul Jackson, third by Joe Korty.
 */

#define CHUNKSZ				32
#define nbits_to_hold_value(val)	fls(val)
#define BASEDEC 10		/* fancier cpuset lists input in decimal */

/**
 * bitmap_scnprintf - convert bitmap to an ASCII hex string.
 * @buf: byte buffer into which string is placed
 * @buflen: reserved size of @buf, in bytes
 * @maskp: pointer to bitmap to convert
 * @nmaskbits: size of bitmap, in bits
 *
 * Exactly @nmaskbits bits are displayed.  Hex digits are grouped into
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 * comma-separated sets of eight digits per set.  Returns the number of
 * characters which were written to *buf, excluding the trailing \0.
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 */
int bitmap_scnprintf(char *buf, unsigned int buflen,
	const unsigned long *maskp, int nmaskbits)
{
	int i, word, bit, len = 0;
	unsigned long val;
	const char *sep = "";
	int chunksz;
	u32 chunkmask;

	chunksz = nmaskbits & (CHUNKSZ - 1);
	if (chunksz == 0)
		chunksz = CHUNKSZ;

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	i = ALIGN(nmaskbits, CHUNKSZ) - CHUNKSZ;
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	for (; i >= 0; i -= CHUNKSZ) {
		chunkmask = ((1ULL << chunksz) - 1);
		word = i / BITS_PER_LONG;
		bit = i % BITS_PER_LONG;
		val = (maskp[word] >> bit) & chunkmask;
		len += scnprintf(buf+len, buflen-len, "%s%0*lx", sep,
			(chunksz+3)/4, val);
		chunksz = CHUNKSZ;
		sep = ",";
	}
	return len;
}
EXPORT_SYMBOL(bitmap_scnprintf);

/**
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 * __bitmap_parse - convert an ASCII hex string into a bitmap.
 * @buf: pointer to buffer containing string.
 * @buflen: buffer size in bytes.  If string is smaller than this
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 *    then it must be terminated with a \0.
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 * @is_user: location of buffer, 0 indicates kernel space
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 * @maskp: pointer to bitmap array that will contain result.
 * @nmaskbits: size of bitmap, in bits.
 *
 * Commas group hex digits into chunks.  Each chunk defines exactly 32
 * bits of the resultant bitmask.  No chunk may specify a value larger
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 * than 32 bits (%-EOVERFLOW), and if a chunk specifies a smaller value
 * then leading 0-bits are prepended.  %-EINVAL is returned for illegal
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 * characters and for grouping errors such as "1,,5", ",44", "," and "".
 * Leading and trailing whitespace accepted, but not embedded whitespace.
 */
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int __bitmap_parse(const char *buf, unsigned int buflen,
		int is_user, unsigned long *maskp,
		int nmaskbits)
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{
	int c, old_c, totaldigits, ndigits, nchunks, nbits;
	u32 chunk;
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	const char __user __force *ubuf = (const char __user __force *)buf;
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	bitmap_zero(maskp, nmaskbits);

	nchunks = nbits = totaldigits = c = 0;
	do {
		chunk = ndigits = 0;

		/* Get the next chunk of the bitmap */
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		while (buflen) {
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			old_c = c;
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			if (is_user) {
				if (__get_user(c, ubuf++))
					return -EFAULT;
			}
			else
				c = *buf++;
			buflen--;
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			if (isspace(c))
				continue;

			/*
			 * If the last character was a space and the current
			 * character isn't '\0', we've got embedded whitespace.
			 * This is a no-no, so throw an error.
			 */
			if (totaldigits && c && isspace(old_c))
				return -EINVAL;

			/* A '\0' or a ',' signal the end of the chunk */
			if (c == '\0' || c == ',')
				break;

			if (!isxdigit(c))
				return -EINVAL;

			/*
			 * Make sure there are at least 4 free bits in 'chunk'.
			 * If not, this hexdigit will overflow 'chunk', so
			 * throw an error.
			 */
			if (chunk & ~((1UL << (CHUNKSZ - 4)) - 1))
				return -EOVERFLOW;

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			chunk = (chunk << 4) | hex_to_bin(c);
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			ndigits++; totaldigits++;
		}
		if (ndigits == 0)
			return -EINVAL;
		if (nchunks == 0 && chunk == 0)
			continue;

		__bitmap_shift_left(maskp, maskp, CHUNKSZ, nmaskbits);
		*maskp |= chunk;
		nchunks++;
		nbits += (nchunks == 1) ? nbits_to_hold_value(chunk) : CHUNKSZ;
		if (nbits > nmaskbits)
			return -EOVERFLOW;
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	} while (buflen && c == ',');
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	return 0;
}
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EXPORT_SYMBOL(__bitmap_parse);

/**
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 * bitmap_parse_user - convert an ASCII hex string in a user buffer into a bitmap
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 *
 * @ubuf: pointer to user buffer containing string.
 * @ulen: buffer size in bytes.  If string is smaller than this
 *    then it must be terminated with a \0.
 * @maskp: pointer to bitmap array that will contain result.
 * @nmaskbits: size of bitmap, in bits.
 *
 * Wrapper for __bitmap_parse(), providing it with user buffer.
 *
 * We cannot have this as an inline function in bitmap.h because it needs
 * linux/uaccess.h to get the access_ok() declaration and this causes
 * cyclic dependencies.
 */
int bitmap_parse_user(const char __user *ubuf,
			unsigned int ulen, unsigned long *maskp,
			int nmaskbits)
{
	if (!access_ok(VERIFY_READ, ubuf, ulen))
		return -EFAULT;
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	return __bitmap_parse((const char __force *)ubuf,
				ulen, 1, maskp, nmaskbits);

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}
EXPORT_SYMBOL(bitmap_parse_user);
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/*
 * bscnl_emit(buf, buflen, rbot, rtop, bp)
 *
 * Helper routine for bitmap_scnlistprintf().  Write decimal number
 * or range to buf, suppressing output past buf+buflen, with optional
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 * comma-prefix.  Return len of what was written to *buf, excluding the
 * trailing \0.
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 */
static inline int bscnl_emit(char *buf, int buflen, int rbot, int rtop, int len)
{
	if (len > 0)
		len += scnprintf(buf + len, buflen - len, ",");
	if (rbot == rtop)
		len += scnprintf(buf + len, buflen - len, "%d", rbot);
	else
		len += scnprintf(buf + len, buflen - len, "%d-%d", rbot, rtop);
	return len;
}

/**
 * bitmap_scnlistprintf - convert bitmap to list format ASCII string
 * @buf: byte buffer into which string is placed
 * @buflen: reserved size of @buf, in bytes
 * @maskp: pointer to bitmap to convert
 * @nmaskbits: size of bitmap, in bits
 *
 * Output format is a comma-separated list of decimal numbers and
 * ranges.  Consecutively set bits are shown as two hyphen-separated
 * decimal numbers, the smallest and largest bit numbers set in
 * the range.  Output format is compatible with the format
 * accepted as input by bitmap_parselist().
 *
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 * The return value is the number of characters which were written to *buf
 * excluding the trailing '\0', as per ISO C99's scnprintf.
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 */
int bitmap_scnlistprintf(char *buf, unsigned int buflen,
	const unsigned long *maskp, int nmaskbits)
{
	int len = 0;
	/* current bit is 'cur', most recently seen range is [rbot, rtop] */
	int cur, rbot, rtop;

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	if (buflen == 0)
		return 0;
	buf[0] = 0;

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	rbot = cur = find_first_bit(maskp, nmaskbits);
	while (cur < nmaskbits) {
		rtop = cur;
		cur = find_next_bit(maskp, nmaskbits, cur+1);
		if (cur >= nmaskbits || cur > rtop + 1) {
			len = bscnl_emit(buf, buflen, rbot, rtop, len);
			rbot = cur;
		}
	}
	return len;
}
EXPORT_SYMBOL(bitmap_scnlistprintf);

590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616
/**
 * bitmap_print_to_pagebuf - convert bitmap to list or hex format ASCII string
 * @list: indicates whether the bitmap must be list
 * @buf: page aligned buffer into which string is placed
 * @maskp: pointer to bitmap to convert
 * @nmaskbits: size of bitmap, in bits
 *
 * Output format is a comma-separated list of decimal numbers and
 * ranges if list is specified or hex digits grouped into comma-separated
 * sets of 8 digits/set. Returns the number of characters written to buf.
 */
int bitmap_print_to_pagebuf(bool list, char *buf, const unsigned long *maskp,
			    int nmaskbits)
{
	ptrdiff_t len = PTR_ALIGN(buf + PAGE_SIZE - 1, PAGE_SIZE) - buf - 2;
	int n = 0;

	if (len > 1) {
		n = list ? bitmap_scnlistprintf(buf, len, maskp, nmaskbits) :
			   bitmap_scnprintf(buf, len, maskp, nmaskbits);
		buf[n++] = '\n';
		buf[n] = '\0';
	}
	return n;
}
EXPORT_SYMBOL(bitmap_print_to_pagebuf);

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/**
618
 * __bitmap_parselist - convert list format ASCII string to bitmap
619
 * @buf: read nul-terminated user string from this buffer
620 621 622
 * @buflen: buffer size in bytes.  If string is smaller than this
 *    then it must be terminated with a \0.
 * @is_user: location of buffer, 0 indicates kernel space
623
 * @maskp: write resulting mask here
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 * @nmaskbits: number of bits in mask to be written
 *
 * Input format is a comma-separated list of decimal numbers and
 * ranges.  Consecutively set bits are shown as two hyphen-separated
 * decimal numbers, the smallest and largest bit numbers set in
 * the range.
 *
631 632 633 634 635
 * Returns 0 on success, -errno on invalid input strings.
 * Error values:
 *    %-EINVAL: second number in range smaller than first
 *    %-EINVAL: invalid character in string
 *    %-ERANGE: bit number specified too large for mask
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 */
637 638 639
static int __bitmap_parselist(const char *buf, unsigned int buflen,
		int is_user, unsigned long *maskp,
		int nmaskbits)
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{
	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;
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646
	totaldigits = c = 0;
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	bitmap_zero(maskp, nmaskbits);
	do {
649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686
		exp_digit = 1;
		in_range = 0;
		a = b = 0;

		/* Get the next cpu# or a range of cpu#'s */
		while (buflen) {
			old_c = c;
			if (is_user) {
				if (__get_user(c, ubuf++))
					return -EFAULT;
			} else
				c = *buf++;
			buflen--;
			if (isspace(c))
				continue;

			/*
			 * If the last character was a space and the current
			 * character isn't '\0', we've got embedded whitespace.
			 * This is a no-no, so throw an error.
			 */
			if (totaldigits && c && isspace(old_c))
				return -EINVAL;

			/* A '\0' or a ',' signal the end of a cpu# or range */
			if (c == '\0' || c == ',')
				break;

			if (c == '-') {
				if (exp_digit || in_range)
					return -EINVAL;
				b = 0;
				in_range = 1;
				exp_digit = 1;
				continue;
			}

			if (!isdigit(c))
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				return -EINVAL;
688 689 690 691 692 693

			b = b * 10 + (c - '0');
			if (!in_range)
				a = b;
			exp_digit = 0;
			totaldigits++;
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		}
		if (!(a <= b))
			return -EINVAL;
		if (b >= nmaskbits)
			return -ERANGE;
		while (a <= b) {
			set_bit(a, maskp);
			a++;
		}
703
	} while (buflen && c == ',');
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	return 0;
}
706 707 708

int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
{
709 710
	char *nl  = strchrnul(bp, '\n');
	int len = nl - bp;
711 712 713

	return __bitmap_parselist(bp, len, 0, maskp, nmaskbits);
}
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EXPORT_SYMBOL(bitmap_parselist);

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/**
 * bitmap_parselist_user()
 *
 * @ubuf: pointer to user buffer containing string.
 * @ulen: buffer size in bytes.  If string is smaller than this
 *    then it must be terminated with a \0.
 * @maskp: pointer to bitmap array that will contain result.
 * @nmaskbits: size of bitmap, in bits.
 *
 * Wrapper for bitmap_parselist(), providing it with user buffer.
 *
 * We cannot have this as an inline function in bitmap.h because it needs
 * linux/uaccess.h to get the access_ok() declaration and this causes
 * cyclic dependencies.
 */
int bitmap_parselist_user(const char __user *ubuf,
			unsigned int ulen, unsigned long *maskp,
			int nmaskbits)
{
	if (!access_ok(VERIFY_READ, ubuf, ulen))
		return -EFAULT;
738
	return __bitmap_parselist((const char __force *)ubuf,
739 740 741 742 743
					ulen, 1, maskp, nmaskbits);
}
EXPORT_SYMBOL(bitmap_parselist_user);


744
/**
745
 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
746
 *	@buf: pointer to a bitmap
747 748
 *	@pos: a bit position in @buf (0 <= @pos < @nbits)
 *	@nbits: number of valid bit positions in @buf
749
 *
750
 * Map the bit at position @pos in @buf (of length @nbits) 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.
753 754 755
 *
 * If for example, just bits 4 through 7 are set in @buf, then @pos
 * 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
757 758 759 760 761
 * gets mapped to (returns) @ord value 3 in this example, that means
 * that bit 7 is the 3rd (starting with 0th) set bit in @buf.
 *
 * The bit positions 0 through @bits are valid positions in @buf.
 */
762
static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits)
763
{
764
	if (pos >= nbits || !test_bit(pos, buf))
765
		return -1;
766

767
	return __bitmap_weight(buf, pos);
768 769 770
}

/**
771
 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
772 773 774 775 776
 *	@buf: pointer to bitmap
 *	@ord: ordinal bit position (n-th set bit, n >= 0)
 *	@bits: number of valid bit positions in @buf
 *
 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
777 778
 * Value of @ord should be in range 0 <= @ord < weight(buf), else
 * results are undefined.
779 780 781
 *
 * If for example, just bits 4 through 7 are set in @buf, then @ord
 * values 0 through 3 will get mapped to 4 through 7, respectively,
782
 * and all other @ord values return undefined values.  When @ord value 3
783 784 785 786 787
 * gets mapped to (returns) @pos value 7 in this example, that means
 * that the 3rd set bit (starting with 0th) is at position 7 in @buf.
 *
 * The bit positions 0 through @bits are valid positions in @buf.
 */
788
int bitmap_ord_to_pos(const unsigned long *buf, int ord, int bits)
789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808
{
	int pos = 0;

	if (ord >= 0 && ord < bits) {
		int i;

		for (i = find_first_bit(buf, bits);
		     i < bits && ord > 0;
		     i = find_next_bit(buf, bits, i + 1))
	     		ord--;
		if (i < bits && ord == 0)
			pos = i;
	}

	return pos;
}

/**
 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
 *	@dst: remapped result
809
 *	@src: subset to be remapped
810 811 812 813 814 815 816 817 818 819 820
 *	@old: defines domain of map
 *	@new: defines range of map
 *	@bits: number of bits in each of these bitmaps
 *
 * Let @old and @new define a mapping of bit positions, such that
 * whatever position is held by the n-th set bit in @old is mapped
 * to the n-th set bit in @new.  In the more general case, allowing
 * for the possibility that the weight 'w' of @new is less than the
 * weight of @old, map the position of the n-th set bit in @old to
 * the position of the m-th set bit in @new, where m == n % w.
 *
821 822 823
 * If either of the @old and @new bitmaps are empty, or if @src and
 * @dst point to the same location, then this routine copies @src
 * to @dst.
824
 *
825 826
 * The positions of unset bits in @old are mapped to themselves
 * (the identify map).
827 828 829 830 831 832 833
 *
 * Apply the above specified mapping to @src, placing the result in
 * @dst, clearing any bits previously set in @dst.
 *
 * For example, lets say that @old has bits 4 through 7 set, and
 * @new has bits 12 through 15 set.  This defines the mapping of bit
 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
834 835 836
 * bit positions unchanged.  So if say @src comes into this routine
 * with bits 1, 5 and 7 set, then @dst should leave with bits 1,
 * 13 and 15 set.
837 838 839 840 841
 */
void bitmap_remap(unsigned long *dst, const unsigned long *src,
		const unsigned long *old, const unsigned long *new,
		int bits)
{
842
	int oldbit, w;
843 844 845 846

	if (dst == src)		/* following doesn't handle inplace remaps */
		return;
	bitmap_zero(dst, bits);
847 848

	w = bitmap_weight(new, bits);
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	for_each_set_bit(oldbit, src, bits) {
850
	     	int n = bitmap_pos_to_ord(old, oldbit, bits);
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852 853 854 855
		if (n < 0 || w == 0)
			set_bit(oldbit, dst);	/* identity map */
		else
			set_bit(bitmap_ord_to_pos(new, n % w, bits), dst);
856 857 858 859 860 861
	}
}
EXPORT_SYMBOL(bitmap_remap);

/**
 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
862 863 864 865
 *	@oldbit: bit position to be mapped
 *	@old: defines domain of map
 *	@new: defines range of map
 *	@bits: number of bits in each of these bitmaps
866 867 868 869 870 871 872 873
 *
 * Let @old and @new define a mapping of bit positions, such that
 * whatever position is held by the n-th set bit in @old is mapped
 * to the n-th set bit in @new.  In the more general case, allowing
 * for the possibility that the weight 'w' of @new is less than the
 * weight of @old, map the position of the n-th set bit in @old to
 * the position of the m-th set bit in @new, where m == n % w.
 *
874 875
 * The positions of unset bits in @old are mapped to themselves
 * (the identify map).
876 877 878 879 880 881 882
 *
 * Apply the above specified mapping to bit position @oldbit, returning
 * the new bit position.
 *
 * For example, lets say that @old has bits 4 through 7 set, and
 * @new has bits 12 through 15 set.  This defines the mapping of bit
 * position 4 to 12, 5 to 13, 6 to 14 and 7 to 15, and of all other
883 884
 * bit positions unchanged.  So if say @oldbit is 5, then this routine
 * returns 13.
885 886 887 888
 */
int bitmap_bitremap(int oldbit, const unsigned long *old,
				const unsigned long *new, int bits)
{
889 890 891 892 893 894
	int w = bitmap_weight(new, bits);
	int n = bitmap_pos_to_ord(old, oldbit, bits);
	if (n < 0 || w == 0)
		return oldbit;
	else
		return bitmap_ord_to_pos(new, n % w, bits);
895 896 897
}
EXPORT_SYMBOL(bitmap_bitremap);

898 899 900 901 902 903 904 905 906 907 908 909 910 911
/**
 * bitmap_onto - translate one bitmap relative to another
 *	@dst: resulting translated bitmap
 * 	@orig: original untranslated bitmap
 * 	@relmap: bitmap relative to which translated
 *	@bits: number of bits in each of these bitmaps
 *
 * Set the n-th bit of @dst iff there exists some m such that the
 * n-th bit of @relmap is set, the m-th bit of @orig is set, and
 * the n-th bit of @relmap is also the m-th _set_ bit of @relmap.
 * (If you understood the previous sentence the first time your
 * read it, you're overqualified for your current job.)
 *
 * In other words, @orig is mapped onto (surjectively) @dst,
912
 * using the map { <n, m> | the n-th bit of @relmap is the
913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946
 * m-th set bit of @relmap }.
 *
 * Any set bits in @orig above bit number W, where W is the
 * weight of (number of set bits in) @relmap are mapped nowhere.
 * In particular, if for all bits m set in @orig, m >= W, then
 * @dst will end up empty.  In situations where the possibility
 * of such an empty result is not desired, one way to avoid it is
 * to use the bitmap_fold() operator, below, to first fold the
 * @orig bitmap over itself so that all its set bits x are in the
 * range 0 <= x < W.  The bitmap_fold() operator does this by
 * setting the bit (m % W) in @dst, for each bit (m) set in @orig.
 *
 * Example [1] for bitmap_onto():
 *  Let's say @relmap has bits 30-39 set, and @orig has bits
 *  1, 3, 5, 7, 9 and 11 set.  Then on return from this routine,
 *  @dst will have bits 31, 33, 35, 37 and 39 set.
 *
 *  When bit 0 is set in @orig, it means turn on the bit in
 *  @dst corresponding to whatever is the first bit (if any)
 *  that is turned on in @relmap.  Since bit 0 was off in the
 *  above example, we leave off that bit (bit 30) in @dst.
 *
 *  When bit 1 is set in @orig (as in the above example), it
 *  means turn on the bit in @dst corresponding to whatever
 *  is the second bit that is turned on in @relmap.  The second
 *  bit in @relmap that was turned on in the above example was
 *  bit 31, so we turned on bit 31 in @dst.
 *
 *  Similarly, we turned on bits 33, 35, 37 and 39 in @dst,
 *  because they were the 4th, 6th, 8th and 10th set bits
 *  set in @relmap, and the 4th, 6th, 8th and 10th bits of
 *  @orig (i.e. bits 3, 5, 7 and 9) were also set.
 *
 *  When bit 11 is set in @orig, it means turn on the bit in
L
Lucas De Marchi 已提交
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 *  @dst corresponding to whatever is the twelfth bit that is
948 949 950 951 952 953 954 955 956 957 958 959
 *  turned on in @relmap.  In the above example, there were
 *  only ten bits turned on in @relmap (30..39), so that bit
 *  11 was set in @orig had no affect on @dst.
 *
 * Example [2] for bitmap_fold() + bitmap_onto():
 *  Let's say @relmap has these ten bits set:
 *		40 41 42 43 45 48 53 61 74 95
 *  (for the curious, that's 40 plus the first ten terms of the
 *  Fibonacci sequence.)
 *
 *  Further lets say we use the following code, invoking
 *  bitmap_fold() then bitmap_onto, as suggested above to
960
 *  avoid the possibility of an empty @dst result:
961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998
 *
 *	unsigned long *tmp;	// a temporary bitmap's bits
 *
 *	bitmap_fold(tmp, orig, bitmap_weight(relmap, bits), bits);
 *	bitmap_onto(dst, tmp, relmap, bits);
 *
 *  Then this table shows what various values of @dst would be, for
 *  various @orig's.  I list the zero-based positions of each set bit.
 *  The tmp column shows the intermediate result, as computed by
 *  using bitmap_fold() to fold the @orig bitmap modulo ten
 *  (the weight of @relmap).
 *
 *      @orig           tmp            @dst
 *      0                0             40
 *      1                1             41
 *      9                9             95
 *      10               0             40 (*)
 *      1 3 5 7          1 3 5 7       41 43 48 61
 *      0 1 2 3 4        0 1 2 3 4     40 41 42 43 45
 *      0 9 18 27        0 9 8 7       40 61 74 95
 *      0 10 20 30       0             40
 *      0 11 22 33       0 1 2 3       40 41 42 43
 *      0 12 24 36       0 2 4 6       40 42 45 53
 *      78 102 211       1 2 8         41 42 74 (*)
 *
 * (*) For these marked lines, if we hadn't first done bitmap_fold()
 *     into tmp, then the @dst result would have been empty.
 *
 * If either of @orig or @relmap is empty (no set bits), then @dst
 * will be returned empty.
 *
 * If (as explained above) the only set bits in @orig are in positions
 * m where m >= W, (where W is the weight of @relmap) then @dst will
 * once again be returned empty.
 *
 * All bits in @dst not set by the above rule are cleared.
 */
void bitmap_onto(unsigned long *dst, const unsigned long *orig,
999
			const unsigned long *relmap, unsigned int bits)
1000
{
1001
	unsigned int n, m;	/* same meaning as in above comment */
1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017

	if (dst == orig)	/* following doesn't handle inplace mappings */
		return;
	bitmap_zero(dst, bits);

	/*
	 * The following code is a more efficient, but less
	 * obvious, equivalent to the loop:
	 *	for (m = 0; m < bitmap_weight(relmap, bits); m++) {
	 *		n = bitmap_ord_to_pos(orig, m, bits);
	 *		if (test_bit(m, orig))
	 *			set_bit(n, dst);
	 *	}
	 */

	m = 0;
A
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1018
	for_each_set_bit(n, relmap, bits) {
1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031
		/* m == bitmap_pos_to_ord(relmap, n, bits) */
		if (test_bit(m, orig))
			set_bit(n, dst);
		m++;
	}
}
EXPORT_SYMBOL(bitmap_onto);

/**
 * bitmap_fold - fold larger bitmap into smaller, modulo specified size
 *	@dst: resulting smaller bitmap
 *	@orig: original larger bitmap
 *	@sz: specified size
1032
 *	@nbits: number of bits in each of these bitmaps
1033 1034 1035 1036 1037 1038
 *
 * For each bit oldbit in @orig, set bit oldbit mod @sz in @dst.
 * Clear all other bits in @dst.  See further the comment and
 * Example [2] for bitmap_onto() for why and how to use this.
 */
void bitmap_fold(unsigned long *dst, const unsigned long *orig,
1039
			unsigned int sz, unsigned int nbits)
1040
{
1041
	unsigned int oldbit;
1042 1043 1044

	if (dst == orig)	/* following doesn't handle inplace mappings */
		return;
1045
	bitmap_zero(dst, nbits);
1046

1047
	for_each_set_bit(oldbit, orig, nbits)
1048 1049 1050 1051
		set_bit(oldbit % sz, dst);
}
EXPORT_SYMBOL(bitmap_fold);

1052 1053 1054 1055 1056 1057
/*
 * Common code for bitmap_*_region() routines.
 *	bitmap: array of unsigned longs corresponding to the bitmap
 *	pos: the beginning of the region
 *	order: region size (log base 2 of number of bits)
 *	reg_op: operation(s) to perform on that region of bitmap
L
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1058
 *
1059 1060
 * Can set, verify and/or release a region of bits in a bitmap,
 * depending on which combination of REG_OP_* flag bits is set.
L
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1061
 *
1062 1063 1064 1065 1066 1067
 * A region of a bitmap is a sequence of bits in the bitmap, of
 * some size '1 << order' (a power of two), aligned to that same
 * '1 << order' power of two.
 *
 * Returns 1 if REG_OP_ISFREE succeeds (region is all zero bits).
 * Returns 0 in all other cases and reg_ops.
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 */
1069 1070 1071 1072 1073 1074 1075

enum {
	REG_OP_ISFREE,		/* true if region is all zero bits */
	REG_OP_ALLOC,		/* set all bits in region */
	REG_OP_RELEASE,		/* clear all bits in region */
};

1076
static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
L
Linus Torvalds 已提交
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{
1078 1079 1080 1081
	int nbits_reg;		/* number of bits in region */
	int index;		/* index first long of region in bitmap */
	int offset;		/* bit offset region in bitmap[index] */
	int nlongs_reg;		/* num longs spanned by region in bitmap */
1082
	int nbitsinlong;	/* num bits of region in each spanned long */
1083
	unsigned long mask;	/* bitmask for one long of region */
1084
	int i;			/* scans bitmap by longs */
1085
	int ret = 0;		/* return value */
1086

1087 1088 1089 1090 1091 1092 1093 1094 1095
	/*
	 * Either nlongs_reg == 1 (for small orders that fit in one long)
	 * or (offset == 0 && mask == ~0UL) (for larger multiword orders.)
	 */
	nbits_reg = 1 << order;
	index = pos / BITS_PER_LONG;
	offset = pos - (index * BITS_PER_LONG);
	nlongs_reg = BITS_TO_LONGS(nbits_reg);
	nbitsinlong = min(nbits_reg,  BITS_PER_LONG);
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1097 1098 1099 1100
	/*
	 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
	 * overflows if nbitsinlong == BITS_PER_LONG.
	 */
1101
	mask = (1UL << (nbitsinlong - 1));
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1102
	mask += mask - 1;
1103
	mask <<= offset;
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1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122
	switch (reg_op) {
	case REG_OP_ISFREE:
		for (i = 0; i < nlongs_reg; i++) {
			if (bitmap[index + i] & mask)
				goto done;
		}
		ret = 1;	/* all bits in region free (zero) */
		break;

	case REG_OP_ALLOC:
		for (i = 0; i < nlongs_reg; i++)
			bitmap[index + i] |= mask;
		break;

	case REG_OP_RELEASE:
		for (i = 0; i < nlongs_reg; i++)
			bitmap[index + i] &= ~mask;
		break;
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1123
	}
1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141
done:
	return ret;
}

/**
 * bitmap_find_free_region - find a contiguous aligned mem region
 *	@bitmap: array of unsigned longs corresponding to the bitmap
 *	@bits: number of bits in the bitmap
 *	@order: region size (log base 2 of number of bits) to find
 *
 * Find a region of free (zero) bits in a @bitmap of @bits bits and
 * allocate them (set them to one).  Only consider regions of length
 * a power (@order) of two, aligned to that power of two, which
 * makes the search algorithm much faster.
 *
 * Return the bit offset in bitmap of the allocated region,
 * or -errno on failure.
 */
1142
int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
1143
{
1144
	unsigned int pos, end;		/* scans bitmap by regions of size order */
1145

1146
	for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
1147 1148 1149 1150 1151 1152
		if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
			continue;
		__reg_op(bitmap, pos, order, REG_OP_ALLOC);
		return pos;
	}
	return -ENOMEM;
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Linus Torvalds 已提交
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}
EXPORT_SYMBOL(bitmap_find_free_region);

/**
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Paul Jackson 已提交
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 * bitmap_release_region - release allocated bitmap region
1158 1159 1160
 *	@bitmap: array of unsigned longs corresponding to the bitmap
 *	@pos: beginning of bit region to release
 *	@order: region size (log base 2 of number of bits) to release
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 *
1162
 * This is the complement to __bitmap_find_free_region() and releases
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 * the found region (by clearing it in the bitmap).
1164 1165
 *
 * No return value.
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 */
1167
void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
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Linus Torvalds 已提交
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{
1169
	__reg_op(bitmap, pos, order, REG_OP_RELEASE);
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}
EXPORT_SYMBOL(bitmap_release_region);

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/**
 * bitmap_allocate_region - allocate bitmap region
1175 1176 1177
 *	@bitmap: array of unsigned longs corresponding to the bitmap
 *	@pos: beginning of bit region to allocate
 *	@order: region size (log base 2 of number of bits) to allocate
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 *
 * Allocate (set bits in) a specified region of a bitmap.
1180
 *
1181
 * Return 0 on success, or %-EBUSY if specified region wasn't
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 * free (not all bits were zero).
 */
1184
int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
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Linus Torvalds 已提交
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{
1186 1187
	if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
		return -EBUSY;
1188
	return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
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Linus Torvalds 已提交
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}
EXPORT_SYMBOL(bitmap_allocate_region);
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David Vrabel 已提交
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/**
 * bitmap_copy_le - copy a bitmap, putting the bits into little-endian order.
 * @dst:   destination buffer
 * @src:   bitmap to copy
 * @nbits: number of bits in the bitmap
 *
 * Require nbits % BITS_PER_LONG == 0.
 */
void bitmap_copy_le(void *dst, const unsigned long *src, int nbits)
{
	unsigned long *d = dst;
	int i;

	for (i = 0; i < nbits/BITS_PER_LONG; i++) {
		if (BITS_PER_LONG == 64)
			d[i] = cpu_to_le64(src[i]);
		else
			d[i] = cpu_to_le32(src[i]);
	}
}
EXPORT_SYMBOL(bitmap_copy_le);