arm64: atomics: implement atomic{,64}_cmpxchg using cmpxchg

We don't need duplicate cmpxchg implementations, so use cmpxchg to
implement atomic{,64}_cmpxchg, like we do for xchg already.

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>

arch/arm64/include/asm/atomic.h

@@ -56,6 +56,7 @@
 #define atomic_read(v)			READ_ONCE((v)->counter)
 #define atomic_set(v, i)		(((v)->counter) = (i))
 #define atomic_xchg(v, new)		xchg(&((v)->counter), (new))
+#define atomic_cmpxchg(v, old, new)	cmpxchg(&((v)->counter), (old), (new))
 
 #define atomic_inc(v)			atomic_add(1, (v))
 #define atomic_dec(v)			atomic_sub(1, (v))
@@ -75,6 +76,7 @@
 #define atomic64_read			atomic_read
 #define atomic64_set			atomic_set
 #define atomic64_xchg			atomic_xchg
+#define atomic64_cmpxchg		atomic_cmpxchg
 
 #define atomic64_inc(v)			atomic64_add(1, (v))
 #define atomic64_dec(v)			atomic64_sub(1, (v))

arch/arm64/include/asm/atomic_ll_sc.h

@@ -93,29 +93,6 @@ ATOMIC_OP(xor, eor)
 #undef ATOMIC_OP_RETURN
 #undef ATOMIC_OP
 
-__LL_SC_INLINE int
-__LL_SC_PREFIX(atomic_cmpxchg(atomic_t *ptr, int old, int new))
-{
-	unsigned long tmp;
-	int oldval;
-
-	asm volatile("// atomic_cmpxchg\n"
-"	prfm	pstl1strm, %2\n"
-"1:	ldxr	%w1, %2\n"
-"	eor	%w0, %w1, %w3\n"
-"	cbnz	%w0, 2f\n"
-"	stlxr	%w0, %w4, %2\n"
-"	cbnz	%w0, 1b\n"
-"	dmb	ish\n"
-"2:"
-	: "=&r" (tmp), "=&r" (oldval), "+Q" (ptr->counter)
-	: "Lr" (old), "r" (new)
-	: "memory");
-
-	return oldval;
-}
-__LL_SC_EXPORT(atomic_cmpxchg);
-
 #define ATOMIC64_OP(op, asm_op)						\
 __LL_SC_INLINE void							\
 __LL_SC_PREFIX(atomic64_##op(long i, atomic64_t *v))			\
@@ -172,29 +149,6 @@ ATOMIC64_OP(xor, eor)
 #undef ATOMIC64_OP_RETURN
 #undef ATOMIC64_OP
 
-__LL_SC_INLINE long
-__LL_SC_PREFIX(atomic64_cmpxchg(atomic64_t *ptr, long old, long new))
-{
-	long oldval;
-	unsigned long res;
-
-	asm volatile("// atomic64_cmpxchg\n"
-"	prfm	pstl1strm, %2\n"
-"1:	ldxr	%1, %2\n"
-"	eor	%0, %1, %3\n"
-"	cbnz	%w0, 2f\n"
-"	stlxr	%w0, %4, %2\n"
-"	cbnz	%w0, 1b\n"
-"	dmb	ish\n"
-"2:"
-	: "=&r" (res), "=&r" (oldval), "+Q" (ptr->counter)
-	: "Lr" (old), "r" (new)
-	: "memory");
-
-	return oldval;
-}
-__LL_SC_EXPORT(atomic64_cmpxchg);
-
 __LL_SC_INLINE long
 __LL_SC_PREFIX(atomic64_dec_if_positive(atomic64_t *v))
 {

arch/arm64/include/asm/atomic_lse.h

@@ -149,28 +149,6 @@ static inline int atomic_sub_return(int i, atomic_t *v)
 	return w0;
 }
 
-static inline int atomic_cmpxchg(atomic_t *ptr, int old, int new)
-{
-	register unsigned long x0 asm ("x0") = (unsigned long)ptr;
-	register int w1 asm ("w1") = old;
-	register int w2 asm ("w2") = new;
-
-	asm volatile(ARM64_LSE_ATOMIC_INSN(
-	/* LL/SC */
-	"	nop\n"
-	__LL_SC_ATOMIC(cmpxchg)
-	"	nop",
-	/* LSE atomics */
-	"	mov	w30, %w[old]\n"
-	"	casal	w30, %w[new], %[v]\n"
-	"	mov	%w[ret], w30")
-	: [ret] "+r" (x0), [v] "+Q" (ptr->counter)
-	: [old] "r" (w1), [new] "r" (w2)
-	: "x30", "memory");
-
-	return x0;
-}
-
 #undef __LL_SC_ATOMIC
 
 #define __LL_SC_ATOMIC64(op)	__LL_SC_CALL(atomic64_##op)
@@ -296,27 +274,6 @@ static inline long atomic64_sub_return(long i, atomic64_t *v)
 
 	return x0;
 }
-static inline long atomic64_cmpxchg(atomic64_t *ptr, long old, long new)
-{
-	register unsigned long x0 asm ("x0") = (unsigned long)ptr;
-	register long x1 asm ("x1") = old;
-	register long x2 asm ("x2") = new;
-
-	asm volatile(ARM64_LSE_ATOMIC_INSN(
-	/* LL/SC */
-	"	nop\n"
-	__LL_SC_ATOMIC64(cmpxchg)
-	"	nop",
-	/* LSE atomics */
-	"	mov	x30, %[old]\n"
-	"	casal	x30, %[new], %[v]\n"
-	"	mov	%[ret], x30")
-	: [ret] "+r" (x0), [v] "+Q" (ptr->counter)
-	: [old] "r" (x1), [new] "r" (x2)
-	: "x30", "memory");
-
-	return x0;
-}
 
 static inline long atomic64_dec_if_positive(atomic64_t *v)
 {