Commit 13f0a02b authored by Yury Norov [NVIDIA]'s avatar Yury Norov [NVIDIA] Committed by Borislav Petkov (AMD)
Browse files

find: Add find_first_andnot_bit() 



The function helps to implement cpumask_andnot() APIs.

Signed-off-by: default avatarYury Norov [NVIDIA] <yury.norov@gmail.com>
Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: default avatarJames Morse <james.morse@arm.com>
Reviewed-by: default avatarReinette Chatre <reinette.chatre@intel.com>
Reviewed-by: default avatarFenghua Yu <fenghuay@nvidia.com>
Tested-by: default avatarJames Morse <james.morse@arm.com>
Tested-by: default avatarTony Luck <tony.luck@intel.com>
Tested-by: default avatarFenghua Yu <fenghuay@nvidia.com>
Link: https://lore.kernel.org/20250515165855.31452-3-james.morse@arm.com
parent 189572bf

include/linux/find.h

+25 −0
Original line number Diff line number Diff line
@@ -29,6 +29,8 @@ unsigned long __find_nth_and_andnot_bit(const unsigned long *addr1, const unsign 
					unsigned long n);

extern unsigned long _find_first_and_bit(const unsigned long *addr1,

					 const unsigned long *addr2, unsigned long size);

unsigned long _find_first_andnot_bit(const unsigned long *addr1, const unsigned long *addr2,

				 unsigned long size);

unsigned long _find_first_and_and_bit(const unsigned long *addr1, const unsigned long *addr2,

				      const unsigned long *addr3, unsigned long size);

extern unsigned long _find_first_zero_bit(const unsigned long *addr, unsigned long size);
@@ -347,6 +349,29 @@ unsigned long find_first_and_bit(const unsigned long *addr1, 
}

#endif



/**

 * find_first_andnot_bit - find the first bit set in 1st memory region and unset in 2nd

 * @addr1: The first address to base the search on

 * @addr2: The second address to base the search on

 * @size: The bitmap size in bits

 *

 * Returns the bit number for the first set bit

 * If no bits are set, returns >= @size.

 */

static __always_inline

unsigned long find_first_andnot_bit(const unsigned long *addr1,

				 const unsigned long *addr2,

				 unsigned long size)

{

	if (small_const_nbits(size)) {

		unsigned long val = *addr1 & (~*addr2) & GENMASK(size - 1, 0);



		return val ? __ffs(val) : size;

	}



	return _find_first_andnot_bit(addr1, addr2, size);

}



/**

 * find_first_and_and_bit - find the first set bit in 3 memory regions

 * @addr1: The first address to base the search on

lib/find_bit.c

+11 −0
Original line number Diff line number Diff line
@@ -116,6 +116,17 @@ unsigned long _find_first_and_bit(const unsigned long *addr1, 
EXPORT_SYMBOL(_find_first_and_bit);

#endif



/*

 * Find the first bit set in 1st memory region and unset in 2nd.

 */

unsigned long _find_first_andnot_bit(const unsigned long *addr1,

				  const unsigned long *addr2,

				  unsigned long size)

{

	return FIND_FIRST_BIT(addr1[idx] & ~addr2[idx], /* nop */, size);

}

EXPORT_SYMBOL(_find_first_andnot_bit);



/*

 * Find the first set bit in three memory regions.

 */