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arm64: atomic64_dec_if_positive: fix incorrect branch condition

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If we attempt to atomic64_dec_if_positive on INT_MIN, we will underflow
and incorrectly decide that the original parameter was positive.

This patches fixes the broken condition code so that we handle this
corner case correctly.

Reviewed-by: Steve Capper <steve.capper@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon 2015-05-29 14:44:06 +01:00
parent 6059a7b6e8
commit db26217e6f
2 changed files with 2 additions and 2 deletions
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2
arch/arm64/include/asm/atomic_ll_sc.h
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@ -159,7 +159,7 @@ __LL_SC_PREFIX(atomic64_dec_if_positive(atomic64_t *v))
" prfm pstl1strm, %2\n"
"1: ldxr %0, %2\n"
" subs %0, %0, #1\n"
" b.mi 2f\n"
" b.lt 2f\n"
" stlxr %w1, %0, %2\n"
" cbnz %w1, 1b\n"
" dmb ish\n"

2
arch/arm64/include/asm/atomic_lse.h
View File

@ -291,7 +291,7 @@ static inline long atomic64_dec_if_positive(atomic64_t *v)
/* LSE atomics */
"1: ldr x30, %[v]\n"
" subs %[ret], x30, #1\n"
" b.mi 2f\n"
" b.lt 2f\n"
" casal x30, %[ret], %[v]\n"
" sub x30, x30, #1\n"
" sub x30, x30, %[ret]\n"