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lib: add bitmap_{from,to}_arr64

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Manipulating 64-bit arrays with bitmap functions is potentially dangerous
because on 32-bit BE machines the order of halfwords doesn't match.
Another issue is that compiler may throw a warning about out-of-boundary
access.

This patch adds bitmap_{from,to}_arr64 functions in addition to existing
bitmap_{from,to}_arr32.

CC: Alexander Gordeev <agordeev@linux.ibm.com>
CC: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
CC: Christian Borntraeger <borntraeger@linux.ibm.com>
CC: Claudio Imbrenda <imbrenda@linux.ibm.com>
CC: David Hildenbrand <david@redhat.com>
CC: Heiko Carstens <hca@linux.ibm.com>
CC: Janosch Frank <frankja@linux.ibm.com>
CC: Rasmus Villemoes <linux@rasmusvillemoes.dk>
CC: Sven Schnelle <svens@linux.ibm.com>
CC: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
This commit is contained in:
Yury Norov
2022-04-28 13:51:13 -07:00
parent e041e0ac53
commit 0a97953fd2
2 changed files with 74 additions and 5 deletions
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56
lib/bitmap.c
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@@ -1512,5 +1512,59 @@ void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap, unsigned int nbits)
buf[halfwords - 1] &= (u32) (UINT_MAX >> ((-nbits) & 31));
}
EXPORT_SYMBOL(bitmap_to_arr32);
#endif
#if (BITS_PER_LONG == 32) && defined(__BIG_ENDIAN)
/**
* bitmap_from_arr64 - copy the contents of u64 array of bits to bitmap
* @bitmap: array of unsigned longs, the destination bitmap
* @buf: array of u64 (in host byte order), the source bitmap
* @nbits: number of bits in @bitmap
*/
void bitmap_from_arr64(unsigned long *bitmap, const u64 *buf, unsigned int nbits)
{
int n;
for (n = nbits; n > 0; n -= 64) {
u64 val = *buf++;
*bitmap++ = val;
if (n > 32)
*bitmap++ = val >> 32;
}
/*
* Clear tail bits in the last word beyond nbits.
*
* Negative index is OK because here we point to the word next
* to the last word of the bitmap, except for nbits == 0, which
* is tested implicitly.
*/
if (nbits % BITS_PER_LONG)
bitmap[-1] &= BITMAP_LAST_WORD_MASK(nbits);
}
EXPORT_SYMBOL(bitmap_from_arr64);
/**
* bitmap_to_arr64 - copy the contents of bitmap to a u64 array of bits
* @buf: array of u64 (in host byte order), the dest bitmap
* @bitmap: array of unsigned longs, the source bitmap
* @nbits: number of bits in @bitmap
*/
void bitmap_to_arr64(u64 *buf, const unsigned long *bitmap, unsigned int nbits)
{
const unsigned long *end = bitmap + BITS_TO_LONGS(nbits);
while (bitmap < end) {
*buf = *bitmap++;
if (bitmap < end)
*buf |= (u64)(*bitmap++) << 32;
buf++;
}
/* Clear tail bits in the last element of array beyond nbits. */
if (nbits % 64)
buf[-1] &= GENMASK_ULL(nbits % 64, 0);
}
EXPORT_SYMBOL(bitmap_to_arr64);
#endif