locking/atomic: x86: add preprocessor symbols

Some atomics can be implemented in several different ways, e.g.
FULL/ACQUIRE/RELEASE ordered atomics can be implemented in terms of
RELAXED atomics, and ACQUIRE/RELEASE/RELAXED can be implemented in terms
of FULL ordered atomics. Other atomics are optional, and don't exist in
some configurations (e.g. not all architectures implement the 128-bit
cmpxchg ops).

Subsequent patches will require that architectures define a preprocessor
symbol for any atomic (or ordering variant) which is optional. This will
make the fallback ifdeffery more robust, and simplify future changes.

Add the required definitions to arch/x86.
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/20230605070124.3741859-13-mark.rutland@arm.com

arch/x86/include/asm/cmpxchg_64.h

@@ -45,11 +45,13 @@ static __always_inline u128 arch_cmpxchg128(volatile u128 *ptr, u128 old, u128 n
 {
 	return __arch_cmpxchg128(ptr, old, new, LOCK_PREFIX);
 }
+#define arch_cmpxchg128 arch_cmpxchg128
 
 static __always_inline u128 arch_cmpxchg128_local(volatile u128 *ptr, u128 old, u128 new)
 {
 	return __arch_cmpxchg128(ptr, old, new,);
 }
+#define arch_cmpxchg128_local arch_cmpxchg128_local
 
 #define __arch_try_cmpxchg128(_ptr, _oldp, _new, _lock)			\
 ({									\
@@ -75,11 +77,13 @@ static __always_inline bool arch_try_cmpxchg128(volatile u128 *ptr, u128 *oldp,
 {
 	return __arch_try_cmpxchg128(ptr, oldp, new, LOCK_PREFIX);
 }
+#define arch_try_cmpxchg128 arch_try_cmpxchg128
 
 static __always_inline bool arch_try_cmpxchg128_local(volatile u128 *ptr, u128 *oldp, u128 new)
 {
 	return __arch_try_cmpxchg128(ptr, oldp, new,);
 }
+#define arch_try_cmpxchg128_local arch_try_cmpxchg128_local
 
 #define system_has_cmpxchg128()		boot_cpu_has(X86_FEATURE_CX16)