bitmap.c 32.4 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.
 */

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
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 *   @nbits : 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.
 */
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void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
			unsigned shift, unsigned nbits)
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{
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	unsigned k, lim = BITS_TO_LONGS(nbits);
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	unsigned off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
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	unsigned long mask = BITMAP_LAST_WORD_MASK(nbits);
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	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];
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			if (off + k + 1 == lim - 1)
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				upper &= mask;
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			upper <<= (BITS_PER_LONG - rem);
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		}
		lower = src[off + k];
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		if (off + k == lim - 1)
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			lower &= mask;
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		lower >>= rem;
		dst[k] = lower | upper;
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	}
	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
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 *   @nbits : 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.
 */

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void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
			unsigned int shift, unsigned int nbits)
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{
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	int k;
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	unsigned int lim = BITS_TO_LONGS(nbits);
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	unsigned int off = shift/BITS_PER_LONG, rem = shift % BITS_PER_LONG;
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	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)
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			lower = src[k - 1] >> (BITS_PER_LONG - rem);
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		else
			lower = 0;
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		upper = src[k] << rem;
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		dst[k + off] = lower | upper;
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	}
	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 */

/**
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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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/**
 * 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) {
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		n = list ? scnprintf(buf, len, "%*pbl", nmaskbits, maskp) :
			   scnprintf(buf, len, "%*pb", nmaskbits, maskp);
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		buf[n++] = '\n';
		buf[n] = '\0';
	}
	return n;
}
EXPORT_SYMBOL(bitmap_print_to_pagebuf);

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/**
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 * __bitmap_parselist - convert list format ASCII string to bitmap
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 * @buf: read nul-terminated user string from this buffer
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 * @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
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 * @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.
 *
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 * 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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 */
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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;
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	int c, old_c, totaldigits;
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	const char __user __force *ubuf = (const char __user __force *)buf;
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	int exp_digit, in_range;
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	totaldigits = c = 0;
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	bitmap_zero(maskp, nmaskbits);
	do {
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		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;
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			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++;
		}
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	} while (buflen && c == ',');
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	return 0;
}
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int bitmap_parselist(const char *bp, unsigned long *maskp, int nmaskbits)
{
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	char *nl  = strchrnul(bp, '\n');
	int len = nl - bp;
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	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;
603
	return __bitmap_parselist((const char __force *)ubuf,
604 605 606 607 608
					ulen, 1, maskp, nmaskbits);
}
EXPORT_SYMBOL(bitmap_parselist_user);


609
/**
610
 * bitmap_pos_to_ord - find ordinal of set bit at given position in bitmap
611
 *	@buf: pointer to a bitmap
612 613
 *	@pos: a bit position in @buf (0 <= @pos < @nbits)
 *	@nbits: number of valid bit positions in @buf
614
 *
615
 * Map the bit at position @pos in @buf (of length @nbits) to the
616
 * ordinal of which set bit it is.  If it is not set or if @pos
617
 * is not a valid bit position, map to -1.
618 619 620
 *
 * 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,
621
 * and other @pos values will get mapped to -1.  When @pos value 7
622 623 624 625 626
 * 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.
 */
627
static int bitmap_pos_to_ord(const unsigned long *buf, unsigned int pos, unsigned int nbits)
628
{
629
	if (pos >= nbits || !test_bit(pos, buf))
630
		return -1;
631

632
	return __bitmap_weight(buf, pos);
633 634 635
}

/**
636
 * bitmap_ord_to_pos - find position of n-th set bit in bitmap
637 638
 *	@buf: pointer to bitmap
 *	@ord: ordinal bit position (n-th set bit, n >= 0)
639
 *	@nbits: number of valid bit positions in @buf
640 641
 *
 * Map the ordinal offset of bit @ord in @buf to its position in @buf.
642 643
 * Value of @ord should be in range 0 <= @ord < weight(buf). If @ord
 * >= weight(buf), returns @nbits.
644 645 646
 *
 * 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,
647
 * and all other @ord values returns @nbits.  When @ord value 3
648 649 650
 * 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.
 *
651
 * The bit positions 0 through @nbits-1 are valid positions in @buf.
652
 */
653
unsigned int bitmap_ord_to_pos(const unsigned long *buf, unsigned int ord, unsigned int nbits)
654
{
655
	unsigned int pos;
656

657 658 659 660
	for (pos = find_first_bit(buf, nbits);
	     pos < nbits && ord;
	     pos = find_next_bit(buf, nbits, pos + 1))
		ord--;
661 662 663 664 665 666 667

	return pos;
}

/**
 * bitmap_remap - Apply map defined by a pair of bitmaps to another bitmap
 *	@dst: remapped result
668
 *	@src: subset to be remapped
669 670
 *	@old: defines domain of map
 *	@new: defines range of map
671
 *	@nbits: number of bits in each of these bitmaps
672 673 674 675 676 677 678 679
 *
 * 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.
 *
680 681 682
 * 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.
683
 *
684 685
 * The positions of unset bits in @old are mapped to themselves
 * (the identify map).
686 687 688 689 690 691 692
 *
 * 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
693 694 695
 * 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.
696 697 698
 */
void bitmap_remap(unsigned long *dst, const unsigned long *src,
		const unsigned long *old, const unsigned long *new,
699
		unsigned int nbits)
700
{
701
	unsigned int oldbit, w;
702 703 704

	if (dst == src)		/* following doesn't handle inplace remaps */
		return;
705
	bitmap_zero(dst, nbits);
706

707 708 709
	w = bitmap_weight(new, nbits);
	for_each_set_bit(oldbit, src, nbits) {
		int n = bitmap_pos_to_ord(old, oldbit, nbits);
710

711 712 713
		if (n < 0 || w == 0)
			set_bit(oldbit, dst);	/* identity map */
		else
714
			set_bit(bitmap_ord_to_pos(new, n % w, nbits), dst);
715 716 717 718 719 720
	}
}
EXPORT_SYMBOL(bitmap_remap);

/**
 * bitmap_bitremap - Apply map defined by a pair of bitmaps to a single bit
721 722 723 724
 *	@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
725 726 727 728 729 730 731 732
 *
 * 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.
 *
733 734
 * The positions of unset bits in @old are mapped to themselves
 * (the identify map).
735 736 737 738 739 740 741
 *
 * 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
742 743
 * bit positions unchanged.  So if say @oldbit is 5, then this routine
 * returns 13.
744 745 746 747
 */
int bitmap_bitremap(int oldbit, const unsigned long *old,
				const unsigned long *new, int bits)
{
748 749 750 751 752 753
	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);
754 755 756
}
EXPORT_SYMBOL(bitmap_bitremap);

757 758 759 760 761 762 763 764 765 766 767 768 769 770
/**
 * 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,
771
 * using the map { <n, m> | the n-th bit of @relmap is the
772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805
 * 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
806
 *  @dst corresponding to whatever is the twelfth bit that is
807 808 809 810 811 812 813 814 815 816 817 818
 *  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
819
 *  avoid the possibility of an empty @dst result:
820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857
 *
 *	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,
858
			const unsigned long *relmap, unsigned int bits)
859
{
860
	unsigned int n, m;	/* same meaning as in above comment */
861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876

	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;
877
	for_each_set_bit(n, relmap, bits) {
878 879 880 881 882 883 884 885 886 887 888 889 890
		/* 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
891
 *	@nbits: number of bits in each of these bitmaps
892 893 894 895 896 897
 *
 * 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,
898
			unsigned int sz, unsigned int nbits)
899
{
900
	unsigned int oldbit;
901 902 903

	if (dst == orig)	/* following doesn't handle inplace mappings */
		return;
904
	bitmap_zero(dst, nbits);
905

906
	for_each_set_bit(oldbit, orig, nbits)
907 908 909 910
		set_bit(oldbit % sz, dst);
}
EXPORT_SYMBOL(bitmap_fold);

911 912 913 914 915 916
/*
 * 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
Linus Torvalds 已提交
917
 *
918 919
 * 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
Linus Torvalds 已提交
920
 *
921 922 923 924 925 926
 * 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.
L
Linus Torvalds 已提交
927
 */
928 929 930 931 932 933 934

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 */
};

935
static int __reg_op(unsigned long *bitmap, unsigned int pos, int order, int reg_op)
L
Linus Torvalds 已提交
936
{
937 938 939 940
	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 */
941
	int nbitsinlong;	/* num bits of region in each spanned long */
942
	unsigned long mask;	/* bitmask for one long of region */
943
	int i;			/* scans bitmap by longs */
944
	int ret = 0;		/* return value */
945

946 947 948 949 950 951 952 953 954
	/*
	 * 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);
L
Linus Torvalds 已提交
955

956 957 958 959
	/*
	 * Can't do "mask = (1UL << nbitsinlong) - 1", as that
	 * overflows if nbitsinlong == BITS_PER_LONG.
	 */
960
	mask = (1UL << (nbitsinlong - 1));
L
Linus Torvalds 已提交
961
	mask += mask - 1;
962
	mask <<= offset;
L
Linus Torvalds 已提交
963

964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981
	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;
L
Linus Torvalds 已提交
982
	}
983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000
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.
 */
1001
int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order)
1002
{
1003
	unsigned int pos, end;		/* scans bitmap by regions of size order */
1004

1005
	for (pos = 0 ; (end = pos + (1U << order)) <= bits; pos = end) {
1006 1007 1008 1009 1010 1011
		if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
			continue;
		__reg_op(bitmap, pos, order, REG_OP_ALLOC);
		return pos;
	}
	return -ENOMEM;
L
Linus Torvalds 已提交
1012 1013 1014 1015
}
EXPORT_SYMBOL(bitmap_find_free_region);

/**
1016
 * bitmap_release_region - release allocated bitmap region
1017 1018 1019
 *	@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
L
Linus Torvalds 已提交
1020
 *
1021
 * This is the complement to __bitmap_find_free_region() and releases
L
Linus Torvalds 已提交
1022
 * the found region (by clearing it in the bitmap).
1023 1024
 *
 * No return value.
L
Linus Torvalds 已提交
1025
 */
1026
void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order)
L
Linus Torvalds 已提交
1027
{
1028
	__reg_op(bitmap, pos, order, REG_OP_RELEASE);
L
Linus Torvalds 已提交
1029 1030 1031
}
EXPORT_SYMBOL(bitmap_release_region);

1032 1033
/**
 * bitmap_allocate_region - allocate bitmap region
1034 1035 1036
 *	@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
1037 1038
 *
 * Allocate (set bits in) a specified region of a bitmap.
1039
 *
1040
 * Return 0 on success, or %-EBUSY if specified region wasn't
1041 1042
 * free (not all bits were zero).
 */
1043
int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order)
L
Linus Torvalds 已提交
1044
{
1045 1046
	if (!__reg_op(bitmap, pos, order, REG_OP_ISFREE))
		return -EBUSY;
1047
	return __reg_op(bitmap, pos, order, REG_OP_ALLOC);
L
Linus Torvalds 已提交
1048 1049
}
EXPORT_SYMBOL(bitmap_allocate_region);
1050 1051 1052 1053 1054 1055 1056 1057 1058

/**
 * 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.
 */
1059
#ifdef __BIG_ENDIAN
1060
void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits)
1061
{
1062
	unsigned int i;
1063 1064 1065

	for (i = 0; i < nbits/BITS_PER_LONG; i++) {
		if (BITS_PER_LONG == 64)
1066
			dst[i] = cpu_to_le64(src[i]);
1067
		else
1068
			dst[i] = cpu_to_le32(src[i]);
1069 1070 1071
	}
}
EXPORT_SYMBOL(bitmap_copy_le);
1072
#endif
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