bitops: avoid integer overflow in GENMASK(_ULL)
GENMASK(_ULL) performs a left-shift of ~0UL(L), which technically results in an integer overflow. clang raises a warning if the overflow occurs in a preprocessor expression. Clear the low-order bits through a substraction instead of the left-shift to avoid the overflow. (akpm: no change in .text size in my testing) Link: http://lkml.kernel.org/r/20170803212020.24939-1-mka@chromium.org Signed-off-by: Matthias Kaehlcke <mka@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000.
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*/
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#define GENMASK(h, l) \
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(((~0UL) << (l)) & (~0UL >> (BITS_PER_LONG - 1 - (h))))
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(((~0UL) - (1UL << (l)) + 1) & (~0UL >> (BITS_PER_LONG - 1 - (h))))
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#define GENMASK_ULL(h, l) \
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(((~0ULL) << (l)) & (~0ULL >> (BITS_PER_LONG_LONG - 1 - (h))))
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(((~0ULL) - (1ULL << (l)) + 1) & \
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(~0ULL >> (BITS_PER_LONG_LONG - 1 - (h))))
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extern unsigned int __sw_hweight8(unsigned int w);
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extern unsigned int __sw_hweight16(unsigned int w);
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