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s390/spinlock: Generate shorter code for arch_spin_unlock()

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Use mvhhi instead of sth to write a zero to spinlocks. Compared to the
sth variant this avoids the load of zero to a register, and reduces
register pressure.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Heiko Carstens 2024-11-26 14:28:25 +01:00
parent 2c3bc137f1
commit 1200f216a3
1 changed files with 3 additions and 3 deletions
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6
arch/s390/include/asm/spinlock.h
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@ -82,9 +82,9 @@ static inline void arch_spin_unlock(arch_spinlock_t *lp)
kcsan_release();
asm_inline volatile(
ALTERNATIVE("nop", ".insn rre,0xb2fa0000,7,0", ALT_FACILITY(49)) /* NIAI 7 */
" sth %[zero],%[lock]\n"
: [lock] "=R" (((unsigned short *)&lp->lock)[1])
: [zero] "d" (0)
" mvhhi %[lock],0\n"
: [lock] "=Q" (((unsigned short *)&lp->lock)[1])
:
: "memory");
}