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| author | Will Deacon <will.deacon@arm.com> | 2015-05-29 14:26:59 +0100 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2015-07-27 15:28:52 +0100 |
| commit | 0bc671d3f4bee9c31110d096ada0de52380e693d (patch) | |
| tree | 63c5120264072fa4599fc6fe0f92f6a044d48f0c | |
| parent | e9a4b795652f654a7870727e5333c1b709b8736c (diff) | |
| download | linux-0bc671d3f4bee9c31110d096ada0de52380e693d.tar.gz linux-0bc671d3f4bee9c31110d096ada0de52380e693d.tar.bz2 linux-0bc671d3f4bee9c31110d096ada0de52380e693d.zip | |
arm64: cmpxchg: avoid "cc" clobber in ll/sc routines
We can perform the cmpxchg comparison using eor and cbnz which avoids
the "cc" clobber for the ll/sc case and consequently for the LSE case
where we may have to fall-back on the ll/sc code at runtime.
Reviewed-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
| -rw-r--r-- | arch/arm64/include/asm/atomic_ll_sc.h | 14 | ||||
| -rw-r--r-- | arch/arm64/include/asm/atomic_lse.h | 4 |
2 files changed, 8 insertions, 10 deletions
diff --git a/arch/arm64/include/asm/atomic_ll_sc.h b/arch/arm64/include/asm/atomic_ll_sc.h index f89f1e4ba577..c02684d1eab3 100644 --- a/arch/arm64/include/asm/atomic_ll_sc.h +++ b/arch/arm64/include/asm/atomic_ll_sc.h @@ -101,14 +101,13 @@ __LL_SC_PREFIX(atomic_cmpxchg(atomic_t *ptr, int old, int new)) asm volatile("// atomic_cmpxchg\n" "1: ldxr %w1, %2\n" -" cmp %w1, %w3\n" -" b.ne 2f\n" +" eor %w0, %w1, %w3\n" +" cbnz %w0, 2f\n" " stxr %w0, %w4, %2\n" " cbnz %w0, 1b\n" "2:" : "=&r" (tmp), "=&r" (oldval), "+Q" (ptr->counter) - : "Ir" (old), "r" (new) - : "cc"); + : "Lr" (old), "r" (new)); smp_mb(); return oldval; @@ -179,14 +178,13 @@ __LL_SC_PREFIX(atomic64_cmpxchg(atomic64_t *ptr, long old, long new)) asm volatile("// atomic64_cmpxchg\n" "1: ldxr %1, %2\n" -" cmp %1, %3\n" -" b.ne 2f\n" +" eor %0, %1, %3\n" +" cbnz %w0, 2f\n" " stxr %w0, %4, %2\n" " cbnz %w0, 1b\n" "2:" : "=&r" (res), "=&r" (oldval), "+Q" (ptr->counter) - : "Ir" (old), "r" (new) - : "cc"); + : "Lr" (old), "r" (new)); smp_mb(); return oldval; diff --git a/arch/arm64/include/asm/atomic_lse.h b/arch/arm64/include/asm/atomic_lse.h index f3cb1052ab24..a3d21e7cee4f 100644 --- a/arch/arm64/include/asm/atomic_lse.h +++ b/arch/arm64/include/asm/atomic_lse.h @@ -166,7 +166,7 @@ static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new) " mov %w[ret], w30") : [ret] "+r" (x0), [v] "+Q" (ptr->counter) : [old] "r" (w1), [new] "r" (w2) - : "x30", "cc", "memory"); + : "x30", "memory"); return x0; } @@ -313,7 +313,7 @@ static inline long atomic64_cmpxchg(atomic64_t *ptr, long old, long new) " mov %[ret], x30") : [ret] "+r" (x0), [v] "+Q" (ptr->counter) : [old] "r" (x1), [new] "r" (x2) - : "x30", "cc", "memory"); + : "x30", "memory"); return x0; } |