locking/atomic: make atomic*_{cmp,}xchg optional

Most architectures define the atomic/atomic64 xchg and cmpxchg
operations in terms of arch_xchg and arch_cmpxchg respectfully.

Add fallbacks for these cases and remove the trivial cases from arch
code. On some architectures the existing definitions are kept as these
are used to build other arch_atomic*() operations.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20230605070124.3741859-5-mark.rutland@arm.com

arch/alpha/include/asm/atomic.h

@@ -200,16 +200,6 @@ ATOMIC_OPS(xor, xor)
 #undef ATOMIC_OP_RETURN
 #undef ATOMIC_OP
 
-#define arch_atomic64_cmpxchg(v, old, new) \
-	(arch_cmpxchg(&((v)->counter), old, new))
-#define arch_atomic64_xchg(v, new) \
-	(arch_xchg(&((v)->counter), new))
-
-#define arch_atomic_cmpxchg(v, old, new) \
-	(arch_cmpxchg(&((v)->counter), old, new))
-#define arch_atomic_xchg(v, new) \
-	(arch_xchg(&((v)->counter), new))
-
 /**
  * arch_atomic_fetch_add_unless - add unless the number is a given value
  * @v: pointer of type atomic_t

arch/arc/include/asm/atomic.h

@@ -22,30 +22,6 @@
 #include <asm/atomic-spinlock.h>
 #endif
 
-#define arch_atomic_cmpxchg(v, o, n)					\
-({									\
-	arch_cmpxchg(&((v)->counter), (o), (n));			\
-})
-
-#ifdef arch_cmpxchg_relaxed
-#define arch_atomic_cmpxchg_relaxed(v, o, n)				\
-({									\
-	arch_cmpxchg_relaxed(&((v)->counter), (o), (n));		\
-})
-#endif
-
-#define arch_atomic_xchg(v, n)						\
-({									\
-	arch_xchg(&((v)->counter), (n));				\
-})
-
-#ifdef arch_xchg_relaxed
-#define arch_atomic_xchg_relaxed(v, n)					\
-({									\
-	arch_xchg_relaxed(&((v)->counter), (n));			\
-})
-#endif
-
 /*
  * 64-bit atomics
  */

arch/arc/include/asm/atomic64-arcv2.h

@@ -159,6 +159,7 @@ arch_atomic64_cmpxchg(atomic64_t *ptr, s64 expected, s64 new)
 
 	return prev;
 }
+#define arch_atomic64_cmpxchg arch_atomic64_cmpxchg
 
 static inline s64 arch_atomic64_xchg(atomic64_t *ptr, s64 new)
 {
@@ -179,6 +180,7 @@ static inline s64 arch_atomic64_xchg(atomic64_t *ptr, s64 new)
 
 	return prev;
 }
+#define arch_atomic64_xchg arch_atomic64_xchg
 
 /**
  * arch_atomic64_dec_if_positive - decrement by 1 if old value positive

arch/arm/include/asm/atomic.h

@@ -210,6 +210,7 @@ static inline int arch_atomic_cmpxchg(atomic_t *v, int old, int new)
 
 	return ret;
 }
+#define arch_atomic_cmpxchg arch_atomic_cmpxchg
 
 #define arch_atomic_fetch_andnot		arch_atomic_fetch_andnot
 
@@ -240,8 +241,6 @@ ATOMIC_OPS(xor, ^=, eor)
 #undef ATOMIC_OP_RETURN
 #undef ATOMIC_OP
 
-#define arch_atomic_xchg(v, new) (arch_xchg(&((v)->counter), new))
-
 #ifndef CONFIG_GENERIC_ATOMIC64
 typedef struct {
 	s64 counter;

arch/arm64/include/asm/atomic.h

@@ -142,24 +142,6 @@ static __always_inline long arch_atomic64_dec_if_positive(atomic64_t *v)
 #define arch_atomic_fetch_xor_release		arch_atomic_fetch_xor_release
 #define arch_atomic_fetch_xor			arch_atomic_fetch_xor
 
-#define arch_atomic_xchg_relaxed(v, new) \
-	arch_xchg_relaxed(&((v)->counter), (new))
-#define arch_atomic_xchg_acquire(v, new) \
-	arch_xchg_acquire(&((v)->counter), (new))
-#define arch_atomic_xchg_release(v, new) \
-	arch_xchg_release(&((v)->counter), (new))
-#define arch_atomic_xchg(v, new) \
-	arch_xchg(&((v)->counter), (new))
-
-#define arch_atomic_cmpxchg_relaxed(v, old, new) \
-	arch_cmpxchg_relaxed(&((v)->counter), (old), (new))
-#define arch_atomic_cmpxchg_acquire(v, old, new) \
-	arch_cmpxchg_acquire(&((v)->counter), (old), (new))
-#define arch_atomic_cmpxchg_release(v, old, new) \
-	arch_cmpxchg_release(&((v)->counter), (old), (new))
-#define arch_atomic_cmpxchg(v, old, new) \
-	arch_cmpxchg(&((v)->counter), (old), (new))
-
 #define arch_atomic_andnot			arch_atomic_andnot
 
 /*
@@ -209,16 +191,6 @@ static __always_inline long arch_atomic64_dec_if_positive(atomic64_t *v)
 #define arch_atomic64_fetch_xor_release		arch_atomic64_fetch_xor_release
 #define arch_atomic64_fetch_xor			arch_atomic64_fetch_xor
 
-#define arch_atomic64_xchg_relaxed		arch_atomic_xchg_relaxed
-#define arch_atomic64_xchg_acquire		arch_atomic_xchg_acquire
-#define arch_atomic64_xchg_release		arch_atomic_xchg_release
-#define arch_atomic64_xchg			arch_atomic_xchg
-
-#define arch_atomic64_cmpxchg_relaxed		arch_atomic_cmpxchg_relaxed
-#define arch_atomic64_cmpxchg_acquire		arch_atomic_cmpxchg_acquire
-#define arch_atomic64_cmpxchg_release		arch_atomic_cmpxchg_release
-#define arch_atomic64_cmpxchg			arch_atomic_cmpxchg
-
 #define arch_atomic64_andnot			arch_atomic64_andnot
 
 #define arch_atomic64_dec_if_positive		arch_atomic64_dec_if_positive

arch/csky/include/asm/atomic.h

@@ -195,41 +195,6 @@ arch_atomic_dec_if_positive(atomic_t *v)
 }
 #define arch_atomic_dec_if_positive arch_atomic_dec_if_positive
 
-#define ATOMIC_OP()							\
-static __always_inline							\
-int arch_atomic_xchg_relaxed(atomic_t *v, int n)			\
-{									\
-	return __xchg_relaxed(n, &(v->counter), 4);			\
-}									\
-static __always_inline							\
-int arch_atomic_cmpxchg_relaxed(atomic_t *v, int o, int n)		\
-{									\
-	return __cmpxchg_relaxed(&(v->counter), o, n, 4);		\
-}									\
-static __always_inline							\
-int arch_atomic_cmpxchg_acquire(atomic_t *v, int o, int n)		\
-{									\
-	return __cmpxchg_acquire(&(v->counter), o, n, 4);		\
-}									\
-static __always_inline							\
-int arch_atomic_cmpxchg(atomic_t *v, int o, int n)			\
-{									\
-	return __cmpxchg(&(v->counter), o, n, 4);			\
-}
-
-#define ATOMIC_OPS()							\
-	ATOMIC_OP()
-
-ATOMIC_OPS()
-
-#define arch_atomic_xchg_relaxed	arch_atomic_xchg_relaxed
-#define arch_atomic_cmpxchg_relaxed	arch_atomic_cmpxchg_relaxed
-#define arch_atomic_cmpxchg_acquire	arch_atomic_cmpxchg_acquire
-#define arch_atomic_cmpxchg		arch_atomic_cmpxchg
-
-#undef ATOMIC_OPS
-#undef ATOMIC_OP
-
 #else
 #include <asm-generic/atomic.h>
 #endif

arch/hexagon/include/asm/atomic.h

@@ -36,12 +36,6 @@ static inline void arch_atomic_set(atomic_t *v, int new)
  */
 #define arch_atomic_read(v)		READ_ONCE((v)->counter)
 
-#define arch_atomic_xchg(v, new)					\
-	(arch_xchg(&((v)->counter), (new)))
-
-#define arch_atomic_cmpxchg(v, old, new)				\
-	(arch_cmpxchg(&((v)->counter), (old), (new)))
-
 #define ATOMIC_OP(op)							\
 static inline void arch_atomic_##op(int i, atomic_t *v)			\
 {									\

arch/ia64/include/asm/atomic.h

@@ -207,13 +207,6 @@ ATOMIC64_FETCH_OP(xor, ^)
 #undef ATOMIC64_FETCH_OP
 #undef ATOMIC64_OP
 
-#define arch_atomic_cmpxchg(v, old, new) (arch_cmpxchg(&((v)->counter), old, new))
-#define arch_atomic_xchg(v, new) (arch_xchg(&((v)->counter), new))
-
-#define arch_atomic64_cmpxchg(v, old, new) \
-	(arch_cmpxchg(&((v)->counter), old, new))
-#define arch_atomic64_xchg(v, new) (arch_xchg(&((v)->counter), new))
-
 #define arch_atomic_add(i,v)		(void)arch_atomic_add_return((i), (v))
 #define arch_atomic_sub(i,v)		(void)arch_atomic_sub_return((i), (v))
 

arch/loongarch/include/asm/atomic.h

@@ -181,9 +181,6 @@ static inline int arch_atomic_sub_if_positive(int i, atomic_t *v)
 	return result;
 }
 
-#define arch_atomic_cmpxchg(v, o, n) (arch_cmpxchg(&((v)->counter), (o), (n)))
-#define arch_atomic_xchg(v, new) (arch_xchg(&((v)->counter), (new)))
-
 /*
  * arch_atomic_dec_if_positive - decrement by 1 if old value positive
  * @v: pointer of type atomic_t
@@ -342,10 +339,6 @@ static inline long arch_atomic64_sub_if_positive(long i, atomic64_t *v)
 	return result;
 }
 
-#define arch_atomic64_cmpxchg(v, o, n) \
-	((__typeof__((v)->counter))arch_cmpxchg(&((v)->counter), (o), (n)))
-#define arch_atomic64_xchg(v, new) (arch_xchg(&((v)->counter), (new)))
-
 /*
  * arch_atomic64_dec_if_positive - decrement by 1 if old value positive
  * @v: pointer of type atomic64_t

arch/m68k/include/asm/atomic.h

@@ -158,12 +158,7 @@ static inline int arch_atomic_inc_and_test(atomic_t *v)
 }
 #define arch_atomic_inc_and_test arch_atomic_inc_and_test
 
-#ifdef CONFIG_RMW_INSNS
-
-#define arch_atomic_cmpxchg(v, o, n) ((int)arch_cmpxchg(&((v)->counter), (o), (n)))
-#define arch_atomic_xchg(v, new) (arch_xchg(&((v)->counter), new))
-
-#else /* !CONFIG_RMW_INSNS */
+#ifndef CONFIG_RMW_INSNS
 
 static inline int arch_atomic_cmpxchg(atomic_t *v, int old, int new)
 {
@@ -177,6 +172,7 @@ static inline int arch_atomic_cmpxchg(atomic_t *v, int old, int new)
 	local_irq_restore(flags);
 	return prev;
 }
+#define arch_atomic_cmpxchg arch_atomic_cmpxchg
 
 static inline int arch_atomic_xchg(atomic_t *v, int new)
 {
@@ -189,6 +185,7 @@ static inline int arch_atomic_xchg(atomic_t *v, int new)
 	local_irq_restore(flags);
 	return prev;
 }
+#define arch_atomic_xchg arch_atomic_xchg
 
 #endif /* !CONFIG_RMW_INSNS */
 

arch/mips/include/asm/atomic.h

@@ -33,17 +33,6 @@ static __always_inline void arch_##pfx##_set(pfx##_t *v, type i)	\
 {									\
 	WRITE_ONCE(v->counter, i);					\
 }									\
-									\
-static __always_inline type						\
-arch_##pfx##_cmpxchg(pfx##_t *v, type o, type n)			\
-{									\
-	return arch_cmpxchg(&v->counter, o, n);				\
-}									\
-									\
-static __always_inline type arch_##pfx##_xchg(pfx##_t *v, type n)	\
-{									\
-	return arch_xchg(&v->counter, n);				\
-}
 
 ATOMIC_OPS(atomic, int)
 

arch/openrisc/include/asm/atomic.h

@@ -130,7 +130,4 @@ static inline int arch_atomic_fetch_add_unless(atomic_t *v, int a, int u)
 
 #include <asm/cmpxchg.h>
 
-#define arch_atomic_xchg(ptr, v)		(arch_xchg(&(ptr)->counter, (v)))
-#define arch_atomic_cmpxchg(v, old, new)	(arch_cmpxchg(&((v)->counter), (old), (new)))
-
 #endif /* __ASM_OPENRISC_ATOMIC_H */

arch/parisc/include/asm/atomic.h

@@ -73,10 +73,6 @@ static __inline__ int arch_atomic_read(const atomic_t *v)
 	return READ_ONCE((v)->counter);
 }
 
-/* exported interface */
-#define arch_atomic_cmpxchg(v, o, n)	(arch_cmpxchg(&((v)->counter), (o), (n)))
-#define arch_atomic_xchg(v, new)	(arch_xchg(&((v)->counter), new))
-
 #define ATOMIC_OP(op, c_op)						\
 static __inline__ void arch_atomic_##op(int i, atomic_t *v)		\
 {									\
@@ -218,11 +214,6 @@ arch_atomic64_read(const atomic64_t *v)
 	return READ_ONCE((v)->counter);
 }
 
-/* exported interface */
-#define arch_atomic64_cmpxchg(v, o, n) \
-	((__typeof__((v)->counter))arch_cmpxchg(&((v)->counter), (o), (n)))
-#define arch_atomic64_xchg(v, new) (arch_xchg(&((v)->counter), new))
-
 #endif /* !CONFIG_64BIT */
 
 

arch/powerpc/include/asm/atomic.h

@@ -126,18 +126,6 @@ ATOMIC_OPS(xor, xor, "", K)
 #undef ATOMIC_OP_RETURN_RELAXED
 #undef ATOMIC_OP
 
-#define arch_atomic_cmpxchg(v, o, n) \
-	(arch_cmpxchg(&((v)->counter), (o), (n)))
-#define arch_atomic_cmpxchg_relaxed(v, o, n) \
-	arch_cmpxchg_relaxed(&((v)->counter), (o), (n))
-#define arch_atomic_cmpxchg_acquire(v, o, n) \
-	arch_cmpxchg_acquire(&((v)->counter), (o), (n))
-
-#define arch_atomic_xchg(v, new) \
-	(arch_xchg(&((v)->counter), new))
-#define arch_atomic_xchg_relaxed(v, new) \
-	arch_xchg_relaxed(&((v)->counter), (new))
-
 /**
  * atomic_fetch_add_unless - add unless the number is a given value
  * @v: pointer of type atomic_t
@@ -396,18 +384,6 @@ static __inline__ s64 arch_atomic64_dec_if_positive(atomic64_t *v)
 }
 #define arch_atomic64_dec_if_positive arch_atomic64_dec_if_positive
 
-#define arch_atomic64_cmpxchg(v, o, n) \
-	(arch_cmpxchg(&((v)->counter), (o), (n)))
-#define arch_atomic64_cmpxchg_relaxed(v, o, n) \
-	arch_cmpxchg_relaxed(&((v)->counter), (o), (n))
-#define arch_atomic64_cmpxchg_acquire(v, o, n) \
-	arch_cmpxchg_acquire(&((v)->counter), (o), (n))
-
-#define arch_atomic64_xchg(v, new) \
-	(arch_xchg(&((v)->counter), new))
-#define arch_atomic64_xchg_relaxed(v, new) \
-	arch_xchg_relaxed(&((v)->counter), (new))
-
 /**
  * atomic64_fetch_add_unless - add unless the number is a given value
  * @v: pointer of type atomic64_t