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riscv: implement xor_unlock_is_negative_byte

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Inspired by the riscv clear_bit_unlock(), this will surely be
more efficient than the generic one defined in filemap.c.

Link: https://lkml.kernel.org/r/20231004165317.1061855-13-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2023-10-04 17:53:12 +01:00 committed by Andrew Morton
parent 51a752c28b
commit 2a667285b5
1 changed files with 13 additions and 0 deletions
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13
arch/riscv/include/asm/bitops.h
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@ -191,6 +191,19 @@ static inline void __clear_bit_unlock(
clear_bit_unlock(nr, addr);
}
static inline bool xor_unlock_is_negative_byte(unsigned long mask,
volatile unsigned long *addr)
{
unsigned long res;
__asm__ __volatile__ (
__AMO(xor) ".rl %0, %2, %1"
: "=r" (res), "+A" (*addr)
: "r" (__NOP(mask))
: "memory");
return (res & BIT(7)) != 0;
}
#define xor_unlock_is_negative_byte xor_unlock_is_negative_byte
#undef __test_and_op_bit
#undef __op_bit
#undef __NOP