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arm64: Avoid redundant type conversions in xchg() and cmpxchg()

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Our atomic instructions (either LSE atomics of LDXR/STXR sequences)
natively support byte, half-word, word and double-word memory accesses
so there is no need to mask the data register prior to being stored.

Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon
2018-09-13 13:30:45 +01:00
parent 3962446922
commit 5ef3fe4cec
3 changed files with 110 additions and 109 deletions
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46
arch/arm64/include/asm/atomic_lse.h
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@@ -446,22 +446,22 @@ static inline long atomic64_dec_if_positive(atomic64_t *v)
#define __LL_SC_CMPXCHG(op) __LL_SC_CALL(__cmpxchg_case_##op)
#define __CMPXCHG_CASE(w, sz, name, mb, cl...) \
static inline unsigned long __cmpxchg_case_##name(volatile void *ptr, \
unsigned long old, \
unsigned long new) \
#define __CMPXCHG_CASE(w, sfx, name, sz, mb, cl...) \
static inline u##sz __cmpxchg_case_##name##sz(volatile void *ptr, \
unsigned long old, \
u##sz new) \
{ \
register unsigned long x0 asm ("x0") = (unsigned long)ptr; \
register unsigned long x1 asm ("x1") = old; \
register unsigned long x2 asm ("x2") = new; \
register u##sz x2 asm ("x2") = new; \
\
asm volatile(ARM64_LSE_ATOMIC_INSN( \
/* LL/SC */ \
__LL_SC_CMPXCHG(name) \
__LL_SC_CMPXCHG(name##sz) \
__nops(2), \
/* LSE atomics */ \
" mov " #w "30, %" #w "[old]\n" \
" cas" #mb #sz "\t" #w "30, %" #w "[new], %[v]\n" \
" cas" #mb #sfx "\t" #w "30, %" #w "[new], %[v]\n" \
" mov %" #w "[ret], " #w "30") \
: [ret] "+r" (x0), [v] "+Q" (*(unsigned long *)ptr) \
: [old] "r" (x1), [new] "r" (x2) \
@@ -470,22 +470,22 @@ static inline unsigned long __cmpxchg_case_##name(volatile void *ptr, \
return x0; \
}
__CMPXCHG_CASE(w, b, 1, )
__CMPXCHG_CASE(w, h, 2, )
__CMPXCHG_CASE(w, , 4, )
__CMPXCHG_CASE(x, , 8, )
__CMPXCHG_CASE(w, b, acq_1, a, "memory")
__CMPXCHG_CASE(w, h, acq_2, a, "memory")
__CMPXCHG_CASE(w, , acq_4, a, "memory")
__CMPXCHG_CASE(x, , acq_8, a, "memory")
__CMPXCHG_CASE(w, b, rel_1, l, "memory")
__CMPXCHG_CASE(w, h, rel_2, l, "memory")
__CMPXCHG_CASE(w, , rel_4, l, "memory")
__CMPXCHG_CASE(x, , rel_8, l, "memory")
__CMPXCHG_CASE(w, b, mb_1, al, "memory")
__CMPXCHG_CASE(w, h, mb_2, al, "memory")
__CMPXCHG_CASE(w, , mb_4, al, "memory")
__CMPXCHG_CASE(x, , mb_8, al, "memory")
__CMPXCHG_CASE(w, b, , 8, )
__CMPXCHG_CASE(w, h, , 16, )
__CMPXCHG_CASE(w, , , 32, )
__CMPXCHG_CASE(x, , , 64, )
__CMPXCHG_CASE(w, b, acq_, 8, a, "memory")
__CMPXCHG_CASE(w, h, acq_, 16, a, "memory")
__CMPXCHG_CASE(w, , acq_, 32, a, "memory")
__CMPXCHG_CASE(x, , acq_, 64, a, "memory")
__CMPXCHG_CASE(w, b, rel_, 8, l, "memory")
__CMPXCHG_CASE(w, h, rel_, 16, l, "memory")
__CMPXCHG_CASE(w, , rel_, 32, l, "memory")
__CMPXCHG_CASE(x, , rel_, 64, l, "memory")
__CMPXCHG_CASE(w, b, mb_, 8, al, "memory")
__CMPXCHG_CASE(w, h, mb_, 16, al, "memory")
__CMPXCHG_CASE(w, , mb_, 32, al, "memory")
__CMPXCHG_CASE(x, , mb_, 64, al, "memory")
#undef __LL_SC_CMPXCHG
#undef __CMPXCHG_CASE